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UNITED STATES
SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

FORM N-1A

REGISTRATION STATEMENT UNDER THE SECURITIES ACT OF 1933      (No. 002-34393)	þ
Pre-Effective Amendment No.	o
Post-Effective Amendment No. 192	þ

and/or

REGISTRATION STATEMENT UNDER THE INVESTMENT COMPANY ACT OF 1940      (No. 811-01879)	þ
Amendment No. 175	þ

(Check appropriate box or boxes.)

JANUS INVESTMENT FUND

(Exact Name of Registrant as Specified in Charter)

151 Detroit Street, Denver, Colorado 80206-4805
(Address of Principal Executive Offices)     (Zip Code)

Registrant’s Telephone Number, including Area Code: 303-333-3863

Stephanie Grauerholz-Lofton – 151 Detroit Street, Denver, Colorado 80206-4805
(Name and Address of Agent for Service)

Approximate Date of Proposed Public Offering:

It is proposed that this filing will become effective (check appropriate box):

þ immediately upon filing pursuant to paragraph (b)

o on (date) pursuant to paragraph (b)

o 60 days after filing pursuant to paragraph (a)(1)

o on (date) pursuant to paragraph (a)(1)

o 75 days after filing pursuant to paragraph (a)(2)

o on (date) pursuant to paragraph (a)(2) of rule 485.

If appropriate, check the following box:

o This post-effective amendment designates a new effective date for a previously filed post-effective amendment.

SIGNATURES

     Pursuant to the requirements of the Securities Act of 1933, as amended, and the Investment Company Act of 1940, as amended, the Registrant certifies that it meets all of the requirements for effectiveness of this Amendment to its Registration Statement pursuant to Rule 485(b) under the Securities Act of 1933, as amended, and has duly caused this Amendment to its Registration Statement to be signed on its behalf by the undersigned, thereto duly authorized, in the City of Denver, and State of Colorado, on the 19^th day of November, 2013.

JANUS INVESTMENT FUND
By:	/s/ Robin C. Beery
	Robin C. Beery, President and
	Chief Executive Officer

     Janus Investment Fund is organized under an Amended and Restated Agreement and Declaration of Trust dated March 18, 2003 (“Declaration of Trust”), a copy of which is on file with the Secretary of State of The Commonwealth of Massachusetts. The obligations of the Registrant hereunder are not binding upon any of the Trustees, shareholders, nominees, officers, agents or employees of the Registrant personally, but bind only the trust property of the Registrant, as provided in the Declaration of Trust of the Registrant. The execution of this Amendment to the Registration Statement has been authorized by the Trustees of the Registrant and this Amendment to the Registration Statement has been signed by an authorized officer of the Registrant, acting as such, and neither such authorization by such Trustees nor such execution by such officer shall be deemed to have been made by any of them personally, but shall bind only the trust property of the Registrant as provided in its Declaration of Trust.

     Pursuant to the requirements of the Securities Act of 1933, as amended, this Amendment to the Registration Statement has been signed below by the following persons in the capacities and on the dates indicated.

Signature	Title	Date
/s/ Robin C. Beery Robin C. Beery	President and Chief Executive Officer (Principal Executive Officer)	November 19, 2013
/s/ Jesper Nergaard Jesper Nergaard	Vice President, Chief Financial Officer, Treasurer and Principal Accounting Officer (Principal Financial Officer and Principal Accounting Officer)	November 19, 2013

C-1

Signature	Title	Date
William F. McCalpin* William F. McCalpin	Chairman and Trustee	November 19, 2013
Alan A. Brown* Alan A. Brown	Trustee	November 19, 2013
William D. Cvengros* William D. Cvengros	Trustee	November 19, 2013
James T. Rothe* James T. Rothe	Trustee	November 19, 2013
William D. Stewart* William D. Stewart	Trustee	November 19, 2013
Linda S. Wolf* Linda S. Wolf	Trustee	November 19, 2013
/s/ Stephanie Grauerholz-Lofton *By: Stephanie Grauerholz-Lofton          Attorney-in-Fact

Pursuant to Powers of Attorney, dated October 28, 2013, incorporated by reference to Exhibit (q)(1) to Post-Effective Amendment No. 191, filed on October 28, 2013

C-2

INDEX OF EXHIBITS

Exhibit Number	Exhibit Title
EX-101.INS	XBRL Instance Document
EX-101.SCH	XBRL Taxonomy Extension Schema Document
EX-101.CAL	XBRL Taxonomy Extension Calculation Linkbase
EX-101.LAB	XBRL Taxonomy Extension Labels Linkbase
EX-101.PRE	XBRL Taxonomy Extension Presentation Linkbase
EX-101.DEF	XBRL Taxonomy Extension Definition Linkbase

C-3

XML

Label	Element	Value
Risk/Return:	rr_RiskReturnAbstract
Registrant Name	dei_EntityRegistrantName	JANUS INVESTMENT FUND
Prospectus Date	rr_ProspectusDate	Oct. 28, 2013
INTECH U.S. Value Fund | Class A, C, S, I, T Shares
Risk/Return:	rr_RiskReturnAbstract
Risk/Return [Heading]	rr_RiskReturnHeading	FUND SUMMARY INTECH U.S. Value Fund
Objective [Heading]	rr_ObjectiveHeading	INVESTMENT OBJECTIVE
Objective, Primary [Text Block]	rr_ObjectivePrimaryTextBlock	INTECH U.S. Value Fund seeks long-term growth of capital.
Expense [Heading]	rr_ExpenseHeading	FEES AND EXPENSES OF THE FUND
Expense Narrative [Text Block]	rr_ExpenseNarrativeTextBlock	This table describes the fees and expenses that you may pay if you buy and hold Shares of the Fund. Each share class has different expenses, but represents an investment in the same Fund.
Shareholder Fees Caption [Text]	rr_ShareholderFeesCaption	SHAREHOLDER FEES (fees paid directly from your investment)
Operating Expenses Caption [Text]	rr_OperatingExpensesCaption	ANNUAL FUND OPERATING EXPENSES (expenses that you pay each year as a percentage of the value of your investment)
Portfolio Turnover [Heading]	rr_PortfolioTurnoverHeading	Portfolio Turnover:
Portfolio Turnover [Text Block]	rr_PortfolioTurnoverTextBlock	The Fund pays transaction costs, such as commissions, when it buys and sells securities (or “turns over” its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when Fund shares are held in a taxable account. These costs, which are not reflected in annual fund operating expenses or in the Example, affect the Fund’s performance. During the most recent fiscal year, the Fund’s portfolio turnover rate was 100% of the average value of its portfolio.
Portfolio Turnover, Rate	rr_PortfolioTurnoverRate	100.00%
Expense Breakpoint Discounts [Text]	rr_ExpenseBreakpointDiscounts	For Class A Shares, you may qualify for sales charge discounts if you and your family invest, or agree to invest in the future, at least $50,000 in the Fund or in other Janus mutual funds. More information about these and other discounts, as well as eligibility requirements for each share class, is available from your financial professional and in the “Purchases” section on page 51 of the Fund’s Prospectus and in the “Purchases” section on page 70 of the Fund’s Statement of Additional Information.
Expense Breakpoint, Minimum Investment Required [Amount]	rr_ExpenseBreakpointMinimumInvestmentRequiredAmount	$ 50,000
Expense Example [Heading]	rr_ExpenseExampleHeading	EXAMPLE:
Expense Example by Year [Heading]	rr_ExpenseExampleByYearHeading	The Example assumes that you invest $10,000 in the Fund for the time periods indicated and reinvest all dividends and distributions. The Example also assumes that your investment has a 5% return each year and that the Fund’s operating expenses remain the same. Although your actual costs may be higher or lower, based on these assumptions your costs would be:
Expense Example Narrative [Text Block]	rr_ExpenseExampleNarrativeTextBlock	The Example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds.
Expense Example by, Year, Caption [Text]	rr_ExpenseExampleByYearCaption	If Shares are redeemed:
Expense Example, No Redemption, By Year, Caption [Text]	rr_ExpenseExampleNoRedemptionByYearCaption	If Shares are not redeemed:
Strategy [Heading]	rr_StrategyHeading	PRINCIPAL INVESTMENT STRATEGIES
Strategy Narrative [Text Block]	rr_StrategyNarrativeTextBlock	The Fund invests, under normal circumstances, at least 80% of its net assets in U.S. common stocks from the universe of the Russell 1000® Value Index, utilizing INTECH’s mathematical investment process. The Russell 1000® Value Index is an unmanaged index that measures the performance of those Russell 1000 companies with lower price-to-book ratios and lower forecasted growth values. The Fund pursues its investment objective by applying a mathematical investment process to construct an investment portfolio from the universe of common stocks within its named benchmark index. The goal of this process is to build a portfolio of stocks in a more efficient combination than the named benchmark index. The process seeks to capitalize on the natural volatility of the market by searching for stocks within the index that have high relative volatility (providing the potential for excess returns) but that essentially move in opposite directions or have low correlation to each other (providing the potential for lower relative risk). By constructing the portfolio in this manner and periodically rebalancing the portfolio to maintain potentially more efficient weightings, INTECH’s mathematical investment process seeks to create a portfolio that, over time, produces returns in excess of its named benchmark index with risks similar to that of the benchmark index. The rebalancing techniques used by INTECH may result in a higher portfolio turnover compared to a “buy and hold” fund strategy. The Fund may lend portfolio securities on a short-term or long-term basis, in an amount equal to up to 1/3 of its total assets as determined at the time of the loan origination.
Risk [Heading]	rr_RiskHeading	PRINCIPAL INVESTMENT RISKS
Risk Narrative [Text Block]	rr_RiskNarrativeTextBlock	The biggest risk is that the Fund’s returns will vary, and you could lose money. The Fund is designed for long-term investors seeking an equity portfolio, including common stocks. Common stocks tend to be more volatile than many other investment choices. Value Investing Risk. Because different types of stocks tend to shift in and out of favor depending on market and economic conditions, “value” stocks may perform differently than other types of stocks and from the market as a whole, and can continue to be undervalued by the market for long periods of time. Market Risk. The value of the Fund’s portfolio may decrease if the value of an individual company or security, or multiple companies or securities, in the portfolio decreases. Further, regardless of how well individual companies or securities perform, the value of the Fund’s portfolio could also decrease if there are deteriorating economic or market conditions. It is important to understand that the value of your investment may fall, sometimes sharply, in response to changes in the market, and you could lose money. Investment Process Risk. The proprietary mathematical investment process used by INTECH may not achieve the desired results. There is a risk that INTECH’s method of identifying stocks with higher volatility than the named benchmark index or its method of identifying stocks that tend to move in the same or opposite direction relative to each other (correlation) will not result in selecting stocks with continuing volatility or the expected correlation. In INTECH’s history, which spans more than 25 years, INTECH’s mathematical investment process has experienced periods of both underperformance and outperformance relative to an identified benchmark. Even when the proprietary mathematical investment process is working appropriately, INTECH expects that there will be periods of underperformance relative to the benchmark. On an occasional basis, INTECH makes changes to its mathematical investment process. These changes may result in changes to the portfolio, might not provide the intended results, and may adversely impact the Fund’s performance. Real Estate Securities Risk. The Fund’s performance may be affected by the risks associated with investments in real estate-related companies. The value of real estate-related companies’ securities is sensitive to changes in real estate values and rental income, property taxes, interest rates, tax and regulatory requirements, supply and demand, and the management skill and creditworthiness of the company. Investments in real estate investment trusts (“REITs”) involve the same risks as other real estate investments. In addition, a REIT could fail to qualify for tax-free pass-through of its income under the Internal Revenue Code or fail to maintain its exemption from registration under the Investment Company Act of 1940, as amended, which could produce adverse economic consequences for the REIT and its investors, including the Fund. Portfolio Turnover Risk. Increased portfolio turnover may result in higher costs, which may have a negative effect on the Fund’s performance. In addition, higher portfolio turnover may result in the acceleration of capital gains and the recognition of greater levels of short-term capital gains, which are taxed at ordinary federal income tax rates when distributed to shareholders. Securities Lending Risk. The Fund may seek to earn additional income through lending its securities to certain qualified broker-dealers and institutions. There is the risk that when portfolio securities are lent, the securities may not be returned on a timely basis, and the Fund may experience delays and costs in recovering the security or gaining access to the collateral provided to the Fund to collateralize the loan. If the Fund is unable to recover a security on loan, the Fund may use the collateral to purchase replacement securities in the market. There is a risk that the value of the collateral could decrease below the cost of the replacement security by the time the replacement investment is made, resulting in a loss to the Fund. An investment in the Fund is not a bank deposit and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency.
Risk Lose Money [Text]	rr_RiskLoseMoney	The biggest risk is that the Fund’s returns will vary, and you could lose money.
Risk Not Insured Depository Institution [Text]	rr_RiskNotInsuredDepositoryInstitution	An investment in the Fund is not a bank deposit and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency.
Bar Chart and Performance Table [Heading]	rr_BarChartAndPerformanceTableHeading	PERFORMANCE INFORMATION
Performance Narrative [Text Block]	rr_PerformanceNarrativeTextBlock	The following information provides some indication of the risks of investing in the Fund by showing how the Fund’s performance has varied over time. Class I Shares, Class A Shares, Class C Shares, and Class S Shares of the Fund commenced operations on July 6, 2009, after the reorganization of each corresponding class of shares of Janus Adviser INTECH Risk-Managed Value Fund (“JAD predecessor fund”) into each respective share class of the Fund. Class T Shares of the Fund commenced operations on July 6, 2009. The performance shown for Class I Shares, Class A Shares, Class C Shares, and Class S Shares for periods prior to July 6, 2009, reflects the historical performance of the JAD predecessor fund’s Class I Shares, Class A Shares, Class C Shares, and Class S Shares prior to the reorganization, calculated using the fees and expenses of each respective share class of the JAD predecessor fund, net of any applicable fee and expense limitations or waivers. The performance shown for Class T Shares for periods prior to July 6, 2009, reflects the historical performance of the JAD predecessor fund’s Class I Shares prior to the reorganization, calculated using the fees and expenses of Class T Shares, without the effect of any fee and expense limitations or waivers. If Class T Shares of the Fund had been available during periods prior to July 6, 2009, the performance shown may have been different. The performance shown for periods following the Fund’s commencement of Class I Shares, Class A Shares, Class C Shares, Class S Shares, and Class T Shares reflects the fees and expenses of each respective share class, net of any applicable fee and expense limitations or waivers. The bar chart depicts the change in performance from year to year during the periods indicated. The bar chart figures do not include any applicable sales charges that an investor may pay when they buy or sell Class A Shares or Class C Shares of the Fund. If sales charges were included, the returns would be lower. The table compares the Fund’s average annual returns for the periods indicated to a broad-based securities market index. The index is not actively managed and is not available for direct investment. All figures assume reinvestment of dividends and distributions. For certain periods, the Fund’s performance reflects the effect of expense waivers. Without the effect of these expense waivers, the performance shown would have been lower. The Fund’s past performance (before and after taxes) does not necessarily indicate how it will perform in the future. Updated performance information is available at janus.com/advisor/mutual-funds or by calling 1-877-335-2687.
Performance Information Illustrates Variability of Returns [Text]	rr_PerformanceInformationIllustratesVariabilityOfReturns	The following information provides some indication of the risks of investing in the Fund by showing how the Fund’s performance has varied over time. The bar chart depicts the change in performance from year to year during the periods indicated.
Performance Additional Market Index [Text]	rr_PerformanceAdditionalMarketIndex	The table compares the Fund’s average annual returns for the periods indicated to a broad-based securities market index. The index is not actively managed and is not available for direct investment. All figures assume reinvestment of dividends and distributions.
Performance Availability Phone [Text]	rr_PerformanceAvailabilityPhone	1-877-335-2687
Performance Availability Website Address [Text]	rr_PerformanceAvailabilityWebSiteAddress	janus.com/advisor/mutual-funds
Performance Past Does Not Indicate Future [Text]	rr_PerformancePastDoesNotIndicateFuture	The Fund’s past performance (before and after taxes) does not necessarily indicate how it will perform in the future.
Bar Chart [Heading]	rr_BarChartHeading	Annual Total Returns for Class I Shares (calendar year-end)
Bar Chart Does Not Reflect Sales Loads [Text]	rr_BarChartDoesNotReflectSalesLoads	The bar chart figures do not include any applicable sales charges that an investor may pay when they buy or sell Class A Shares or Class C Shares of the Fund. If sales charges were included, the returns would be lower.
Bar Chart Closing [Text Block]	rr_BarChartClosingTextBlock	Best Quarter:  Third Quarter 2009  17.79%          Worst Quarter:  Fourth Quarter 2008  −21.39%
Year to Date Return, Label	rr_YearToDateReturnLabel	The Fund’s year-to-date return as of the calendar quarter ended September 30, 2013 was 21.91%.
Performance Table Heading	rr_PerformanceTableHeading	Average Annual Total Returns (periods ended 12/31/12)
Performance Table Uses Highest Federal Rate	rr_PerformanceTableUsesHighestFederalRate	After-tax returns are calculated using the historically highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes.
Performance Table Not Relevant to Tax Deferred	rr_PerformanceTableNotRelevantToTaxDeferred	Actual after-tax returns depend on your individual tax situation and may differ from those shown in the preceding table. The after-tax return information shown above does not apply to Fund shares held through a tax-deferred account, such as a 401(k) plan or an IRA.
Performance Table One Class of after Tax Shown [Text]	rr_PerformanceTableOneClassOfAfterTaxShown	After-tax returns are only shown for Class I Shares of the Fund. After-tax returns for the other classes of Shares will vary from those shown for Class I Shares due to varying sales charges (as applicable), fees, and expenses among the classes.
Performance Table Explanation after Tax Higher	rr_PerformanceTableExplanationAfterTaxHigher	If the Fund incurs a loss, which generates a tax benefit, the Return After Taxes on Distributions and Sale of Fund Shares may exceed the Fund’s other return figures.
Performance Table Narrative	rr_PerformanceTableNarrativeTextBlock	After-tax returns are calculated using distributions for the Fund’s Class I Shares for periods following July 6, 2009; and for the JAD predecessor fund’s Class I Shares for periods prior to July 6, 2009. After-tax returns are calculated using the historically highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes. Actual after-tax returns depend on your individual tax situation and may differ from those shown in the preceding table. The after-tax return information shown above does not apply to Fund shares held through a tax-deferred account, such as a 401(k) plan or an IRA. After-tax returns are only shown for Class I Shares of the Fund. After-tax returns for the other classes of Shares will vary from those shown for Class I Shares due to varying sales charges (as applicable), fees, and expenses among the classes.
Performance Table Closing [Text Block]	rr_PerformanceTableClosingTextBlock	Updated performance information is available at janus.com/advisor/mutual-funds or by calling 1-877-335-2687.
INTECH U.S. Value Fund | Class A, C, S, I, T Shares | Class A
Risk/Return:	rr_RiskReturnAbstract
Shareholder Fees Column [Text]	rr_ShareholderFeesColumnName	Class A
Maximum Sales Charge (load) Imposed on Purchases (as a percentage of offering price)	rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice	5.75%
Maximum Deferred Sales Charge (load) (as a percentage of the lower of original purchase price or redemption proceeds)	rr_MaximumDeferredSalesChargeOverOther	none
Operating Expenses Column [Text]	rr_OperatingExpensesColumnName	Class A
Management Fees	rr_ManagementFeesOverAssets	0.50%
Distribution/Service (12b-1) Fees	rr_DistributionAndService12b1FeesOverAssets	0.25%
Other Expenses	rr_OtherExpensesOverAssets	0.22%
Acquired Fund Fees and Expenses	rr_AcquiredFundFeesAndExpensesOverAssets	0.04%
Total Annual Fund Operating Expenses	rr_ExpensesOverAssets	1.01%
Expense Example, By Year, Column [Text]	rr_ExpenseExampleByYearColumnName	Class A Shares
1 Year	rr_ExpenseExampleYear01	672
3 Years	rr_ExpenseExampleYear03	878
5 Years	rr_ExpenseExampleYear05	1,101
10 Years	rr_ExpenseExampleYear10	1,740
Expense Example, No Redemption, By Year, Column [Text]	rr_ExpenseExampleNoRedemptionByYearColumnName	Class A Shares
1 Year	rr_ExpenseExampleNoRedemptionYear01	672
3 Years	rr_ExpenseExampleNoRedemptionYear03	878
5 Years	rr_ExpenseExampleNoRedemptionYear05	1,101
10 Years	rr_ExpenseExampleNoRedemptionYear10	1,740
INTECH U.S. Value Fund | Class A, C, S, I, T Shares | Class C
Risk/Return:	rr_RiskReturnAbstract
Shareholder Fees Column [Text]	rr_ShareholderFeesColumnName	Class C
Maximum Sales Charge (load) Imposed on Purchases (as a percentage of offering price)	rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice	none
Maximum Deferred Sales Charge (load) (as a percentage of the lower of original purchase price or redemption proceeds)	rr_MaximumDeferredSalesChargeOverOther	1.00%
Operating Expenses Column [Text]	rr_OperatingExpensesColumnName	Class C
Management Fees	rr_ManagementFeesOverAssets	0.50%
Distribution/Service (12b-1) Fees	rr_DistributionAndService12b1FeesOverAssets	1.00%
Other Expenses	rr_OtherExpensesOverAssets	0.20%
Acquired Fund Fees and Expenses	rr_AcquiredFundFeesAndExpensesOverAssets	0.04%
Total Annual Fund Operating Expenses	rr_ExpensesOverAssets	1.74%
Expense Example, By Year, Column [Text]	rr_ExpenseExampleByYearColumnName	Class C Shares
1 Year	rr_ExpenseExampleYear01	277
3 Years	rr_ExpenseExampleYear03	548
5 Years	rr_ExpenseExampleYear05	944
10 Years	rr_ExpenseExampleYear10	2,052
Expense Example, No Redemption, By Year, Column [Text]	rr_ExpenseExampleNoRedemptionByYearColumnName	Class C Shares
1 Year	rr_ExpenseExampleNoRedemptionYear01	177
3 Years	rr_ExpenseExampleNoRedemptionYear03	548
5 Years	rr_ExpenseExampleNoRedemptionYear05	944
10 Years	rr_ExpenseExampleNoRedemptionYear10	2,052
INTECH U.S. Value Fund | Class A, C, S, I, T Shares | Class S
Risk/Return:	rr_RiskReturnAbstract
Shareholder Fees Column [Text]	rr_ShareholderFeesColumnName	Class S
Maximum Sales Charge (load) Imposed on Purchases (as a percentage of offering price)	rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice	none
Maximum Deferred Sales Charge (load) (as a percentage of the lower of original purchase price or redemption proceeds)	rr_MaximumDeferredSalesChargeOverOther	none
Operating Expenses Column [Text]	rr_OperatingExpensesColumnName	Class S
Management Fees	rr_ManagementFeesOverAssets	0.50%
Distribution/Service (12b-1) Fees	rr_DistributionAndService12b1FeesOverAssets	0.25%
Other Expenses	rr_OtherExpensesOverAssets	0.41%
Acquired Fund Fees and Expenses	rr_AcquiredFundFeesAndExpensesOverAssets	0.04%
Total Annual Fund Operating Expenses	rr_ExpensesOverAssets	1.20%
Expense Example, By Year, Column [Text]	rr_ExpenseExampleByYearColumnName	Class S Shares
1 Year	rr_ExpenseExampleYear01	122
3 Years	rr_ExpenseExampleYear03	381
5 Years	rr_ExpenseExampleYear05	660
10 Years	rr_ExpenseExampleYear10	1,455
Expense Example, No Redemption, By Year, Column [Text]	rr_ExpenseExampleNoRedemptionByYearColumnName	Class S Shares
1 Year	rr_ExpenseExampleNoRedemptionYear01	122
3 Years	rr_ExpenseExampleNoRedemptionYear03	381
5 Years	rr_ExpenseExampleNoRedemptionYear05	660
10 Years	rr_ExpenseExampleNoRedemptionYear10	1,455
INTECH U.S. Value Fund | Class A, C, S, I, T Shares | Class I
Risk/Return:	rr_RiskReturnAbstract
Shareholder Fees Column [Text]	rr_ShareholderFeesColumnName	Class I
Maximum Sales Charge (load) Imposed on Purchases (as a percentage of offering price)	rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice	none
Maximum Deferred Sales Charge (load) (as a percentage of the lower of original purchase price or redemption proceeds)	rr_MaximumDeferredSalesChargeOverOther	none
Operating Expenses Column [Text]	rr_OperatingExpensesColumnName	Class I
Management Fees	rr_ManagementFeesOverAssets	0.50%
Distribution/Service (12b-1) Fees	rr_DistributionAndService12b1FeesOverAssets	none
Other Expenses	rr_OtherExpensesOverAssets	0.17%
Acquired Fund Fees and Expenses	rr_AcquiredFundFeesAndExpensesOverAssets	0.04%
Total Annual Fund Operating Expenses	rr_ExpensesOverAssets	0.71%
Expense Example, By Year, Column [Text]	rr_ExpenseExampleByYearColumnName	Class I Shares
1 Year	rr_ExpenseExampleYear01	73
3 Years	rr_ExpenseExampleYear03	227
5 Years	rr_ExpenseExampleYear05	395
10 Years	rr_ExpenseExampleYear10	883
Expense Example, No Redemption, By Year, Column [Text]	rr_ExpenseExampleNoRedemptionByYearColumnName	Class I Shares
1 Year	rr_ExpenseExampleNoRedemptionYear01	73
3 Years	rr_ExpenseExampleNoRedemptionYear03	227
5 Years	rr_ExpenseExampleNoRedemptionYear05	395
10 Years	rr_ExpenseExampleNoRedemptionYear10	883
2006	rr_AnnualReturn2006	17.72%
2007	rr_AnnualReturn2007	1.47%
2008	rr_AnnualReturn2008	(34.79%)
2009	rr_AnnualReturn2009	17.99%
2010	rr_AnnualReturn2010	15.41%
2011	rr_AnnualReturn2011	2.28%
2012	rr_AnnualReturn2012	15.64%
Bar Chart, Year to Date Return, Date	rr_BarChartYearToDateReturnDate	Sep. 30, 2013
Bar Chart, Year to Date Return	rr_BarChartYearToDateReturn	21.91%
Highest Quarterly Return, Label	rr_HighestQuarterlyReturnLabel	Best Quarter:
Highest Quarterly Return, Date	rr_BarChartHighestQuarterlyReturnDate	Sep. 30, 2009
Highest Quarterly Return	rr_BarChartHighestQuarterlyReturn	17.79%
Lowest Quarterly Return, Label	rr_LowestQuarterlyReturnLabel	Worst Quarter:
Lowest Quarterly Return, Date	rr_BarChartLowestQuarterlyReturnDate	Dec. 31, 2008
Lowest Quarterly Return	rr_BarChartLowestQuarterlyReturn	(21.39%)
INTECH U.S. Value Fund | Class A, C, S, I, T Shares | Class T
Risk/Return:	rr_RiskReturnAbstract
Shareholder Fees Column [Text]	rr_ShareholderFeesColumnName	Class T
Maximum Sales Charge (load) Imposed on Purchases (as a percentage of offering price)	rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice	none
Maximum Deferred Sales Charge (load) (as a percentage of the lower of original purchase price or redemption proceeds)	rr_MaximumDeferredSalesChargeOverOther	none
Operating Expenses Column [Text]	rr_OperatingExpensesColumnName	Class T
Management Fees	rr_ManagementFeesOverAssets	0.50%
Distribution/Service (12b-1) Fees	rr_DistributionAndService12b1FeesOverAssets	none
Other Expenses	rr_OtherExpensesOverAssets	0.41%
Acquired Fund Fees and Expenses	rr_AcquiredFundFeesAndExpensesOverAssets	0.04%
Total Annual Fund Operating Expenses	rr_ExpensesOverAssets	0.95%
Expense Example, By Year, Column [Text]	rr_ExpenseExampleByYearColumnName	Class T Shares
1 Year	rr_ExpenseExampleYear01	97
3 Years	rr_ExpenseExampleYear03	303
5 Years	rr_ExpenseExampleYear05	525
10 Years	rr_ExpenseExampleYear10	1,166
Expense Example, No Redemption, By Year, Column [Text]	rr_ExpenseExampleNoRedemptionByYearColumnName	Class T Shares
1 Year	rr_ExpenseExampleNoRedemptionYear01	97
3 Years	rr_ExpenseExampleNoRedemptionYear03	303
5 Years	rr_ExpenseExampleNoRedemptionYear05	525
10 Years	rr_ExpenseExampleNoRedemptionYear10	$ 1,166
INTECH U.S. Value Fund | Class A, C, S, I, T Shares | Return Before Taxes | Class A
Risk/Return:	rr_RiskReturnAbstract
Column	rr_AverageAnnualReturnColumnName	Class A Shares
Label	rr_AverageAnnualReturnLabel	Return Before Taxes	[1]
1 Year	rr_AverageAnnualReturnYear01	8.68%
5 Years	rr_AverageAnnualReturnYear05	(0.42%)
Since Inception of Predecessor Fund	rr_AverageAnnualReturnSinceInception	2.18%
Inception Date	rr_AverageAnnualReturnInceptionDate	Dec. 30, 2005
INTECH U.S. Value Fund | Class A, C, S, I, T Shares | Return Before Taxes | Class C
Risk/Return:	rr_RiskReturnAbstract
Column	rr_AverageAnnualReturnColumnName	Class C Shares
Label	rr_AverageAnnualReturnLabel	Return Before Taxes	[2]
1 Year	rr_AverageAnnualReturnYear01	13.43%
5 Years	rr_AverageAnnualReturnYear05	none
Since Inception of Predecessor Fund	rr_AverageAnnualReturnSinceInception	2.28%
Inception Date	rr_AverageAnnualReturnInceptionDate	Dec. 30, 2005
INTECH U.S. Value Fund | Class A, C, S, I, T Shares | Return Before Taxes | Class S
Risk/Return:	rr_RiskReturnAbstract
Column	rr_AverageAnnualReturnColumnName	Class S Shares
Label	rr_AverageAnnualReturnLabel	Return Before Taxes
1 Year	rr_AverageAnnualReturnYear01	15.14%
5 Years	rr_AverageAnnualReturnYear05	0.54%
Since Inception of Predecessor Fund	rr_AverageAnnualReturnSinceInception	2.81%
Inception Date	rr_AverageAnnualReturnInceptionDate	Dec. 30, 2005
INTECH U.S. Value Fund | Class A, C, S, I, T Shares | Return Before Taxes | Class I
Risk/Return:	rr_RiskReturnAbstract
Column	rr_AverageAnnualReturnColumnName	Class I Shares
Label	rr_AverageAnnualReturnLabel	Return Before Taxes
1 Year	rr_AverageAnnualReturnYear01	15.64%
5 Years	rr_AverageAnnualReturnYear05	0.99%
Since Inception of Predecessor Fund	rr_AverageAnnualReturnSinceInception	3.29%
Inception Date	rr_AverageAnnualReturnInceptionDate	Dec. 30, 2005
INTECH U.S. Value Fund | Class A, C, S, I, T Shares | Return Before Taxes | Class T
Risk/Return:	rr_RiskReturnAbstract
Column	rr_AverageAnnualReturnColumnName	Class T Shares
Label	rr_AverageAnnualReturnLabel	Return Before Taxes
1 Year	rr_AverageAnnualReturnYear01	15.34%
5 Years	rr_AverageAnnualReturnYear05	0.67%
Since Inception of Predecessor Fund	rr_AverageAnnualReturnSinceInception	2.90%
Inception Date	rr_AverageAnnualReturnInceptionDate	Dec. 30, 2005
INTECH U.S. Value Fund | Class A, C, S, I, T Shares | Return After Taxes on Distributions | Class I
Risk/Return:	rr_RiskReturnAbstract
Column	rr_AverageAnnualReturnColumnName	Class I Shares
Label	rr_AverageAnnualReturnLabel	Return After Taxes on Distributions
1 Year	rr_AverageAnnualReturnYear01	15.30%
5 Years	rr_AverageAnnualReturnYear05	0.66%
Since Inception of Predecessor Fund	rr_AverageAnnualReturnSinceInception	2.89%
Inception Date	rr_AverageAnnualReturnInceptionDate	Dec. 30, 2005
INTECH U.S. Value Fund | Class A, C, S, I, T Shares | Return After Taxes on Distributions and Sale of Fund Shares | Class I
Risk/Return:	rr_RiskReturnAbstract
Column	rr_AverageAnnualReturnColumnName	Class I Shares
Label	rr_AverageAnnualReturnLabel	Return After Taxes on Distributions and Sale of Fund Shares	[3]
1 Year	rr_AverageAnnualReturnYear01	10.63%
5 Years	rr_AverageAnnualReturnYear05	0.77%
Since Inception of Predecessor Fund	rr_AverageAnnualReturnSinceInception	2.72%
Inception Date	rr_AverageAnnualReturnInceptionDate	Dec. 30, 2005
INTECH U.S. Value Fund | Class A, C, S, I, T Shares | Russell 1000® Value Index (reflects no deduction for expenses, fees, or taxes)
Risk/Return:	rr_RiskReturnAbstract
Label	rr_AverageAnnualReturnLabel	Russell 1000® Value Index
1 Year	rr_AverageAnnualReturnYear01	17.51%
5 Years	rr_AverageAnnualReturnYear05	0.59%
Since Inception of Predecessor Fund	rr_AverageAnnualReturnSinceInception	3.32%
Inception Date	rr_AverageAnnualReturnInceptionDate	Dec. 30, 2005

[1] Calculated assuming maximum permitted sales loads.

[2] The one year return is calculated to include the contingent deferred sales charge.

[3] If the Fund incurs a loss, which generates a tax benefit, the Return After Taxes on Distributions and Sale of Fund Shares may exceed the Fund's other return figures.

XML

Label	Element	Value
Risk/Return:	rr_RiskReturnAbstract
Registrant Name	dei_EntityRegistrantName	JANUS INVESTMENT FUND
Prospectus Date	rr_ProspectusDate	Oct. 28, 2013
Janus Money Market Fund | Class D Shares
Risk/Return:	rr_RiskReturnAbstract
Risk/Return [Heading]	rr_RiskReturnHeading	FUND SUMMARY Janus Money Market Fund
Objective [Heading]	rr_ObjectiveHeading	INVESTMENT OBJECTIVES
Objective, Primary [Text Block]	rr_ObjectivePrimaryTextBlock	Janus Money Market Fund seeks capital preservation and liquidity with current income as a secondary objective.
Expense [Heading]	rr_ExpenseHeading	FEES AND EXPENSES OF THE FUND
Expense Narrative [Text Block]	rr_ExpenseNarrativeTextBlock	This table describes the fees and expenses that you may pay if you buy and hold Shares of the Fund.
Operating Expenses Caption [Text]	rr_OperatingExpensesCaption	ANNUAL FUND OPERATING EXPENSES (expenses that you pay each year as a percentage of the value of your investment)
Expense Example [Heading]	rr_ExpenseExampleHeading	EXAMPLE:
Expense Example by Year [Heading]	rr_ExpenseExampleByYearHeading	The Example assumes that you invest $10,000 in the Fund for the time periods indicated, reinvest all dividends and distributions, and then redeem all of your Shares at the end of each period. The Example also assumes that your investment has a 5% return each year and that the Fund’s operating expenses remain the same. Although your actual costs may be higher or lower, based on these assumptions your costs would be:
Expense Example Narrative [Text Block]	rr_ExpenseExampleNarrativeTextBlock	The Example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds.
Strategy [Heading]	rr_StrategyHeading	PRINCIPAL INVESTMENT STRATEGIES
Strategy Narrative [Text Block]	rr_StrategyNarrativeTextBlock	The Fund pursues its investment objectives by investing primarily in high quality debt obligations and obligations of financial institutions. Debt obligations may include commercial paper, notes and bonds, and variable amount master demand notes. Obligations of financial institutions include certificates of deposit and time deposits. The Fund also intends to invest in repurchase agreements including those secured by U.S. Government agencies. Some government agencies backed by the full faith and credit of the United States are supported by the issuer’s ability to borrow from the United States Treasury, some are supported only by the credit of the issuer, and some are supported by the United States in some other way. The Fund will: invest in high quality, short-term money market instruments that present minimal credit risks, as determined by Janus Capital invest only in U.S. dollar-denominated instruments that have a remaining maturity of 397 days or less (as calculated pursuant to Rule 2a-7 under the Investment Company Act of 1940, as amended) maintain a dollar-weighted average portfolio maturity of 60 days or less and maintain a dollar-weighted average portfolio life (portfolio maturity measured without reference to any maturity shortening provisions of adjustable rate securities by reference to their interest rate reset dates) of 120 days or less
Risk [Heading]	rr_RiskHeading	PRINCIPAL INVESTMENT RISKS
Risk Narrative [Text Block]	rr_RiskNarrativeTextBlock	Market Risk. The Fund’s yield will vary as the short-term securities in its portfolio mature and the proceeds are reinvested in securities with different interest rates. For capital preservation and liquidity, the Fund may have a greater concentration in short-term securities including, but not limited to, investing up to all of its assets in overnight securities, which may result in a reduction of the Fund's yield. Over time, the real value of the Fund's yield may be eroded by inflation. Although the Fund invests only in high-quality, short-term money market instruments, there is a risk that the value of the securities it holds will fall as a result of changes in interest rates, an issuer's actual or perceived creditworthiness, or an issuer's ability to meet its obligations. The credit quality of the Fund's holdings can change rapidly in certain market environments and any downgrade or default of a portfolio security could cause the Fund's share price or yield to fall. Collateral Risk. With respect to collateral received in repurchase transactions or other investments, the Fund may have significant exposure to financial services, mortgage markets, and government agencies not secured by the full faith and credit of the United States. Such exposure, depending on market conditions, could have a negative impact on the Fund, including minimizing the value of any collateral. Money Market Risk. An investment in the Fund is not a bank deposit and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency. Although the Fund seeks to preserve the value of your investment at $1.00 per share, it is possible to lose money by investing in the Fund.
Risk Money Market Fund [Text]	rr_RiskMoneyMarketFund	Money Market Risk. An investment in the Fund is not a bank deposit and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency. Although the Fund seeks to preserve the value of your investment at $1.00 per share, it is possible to lose money by investing in the Fund.
Bar Chart and Performance Table [Heading]	rr_BarChartAndPerformanceTableHeading	PERFORMANCE INFORMATION
Performance Narrative [Text Block]	rr_PerformanceNarrativeTextBlock	The following information provides some indication of the risks of investing in the Fund by showing how the Fund’s performance has varied over time. Class D Shares of the Fund commenced operations on February 16, 2010, as a result of the restructuring of Class J Shares, the predecessor share class. The performance shown for Class D Shares for periods prior to February 16, 2010, reflects the performance of the Fund’s former Class J Shares, calculated using the fees and expenses in effect during the periods shown, net of any applicable fee and expense limitations or waivers. If Class D Shares of the Fund had been available during periods prior to February 16, 2010, the performance shown may have been different. The performance shown for periods following the Fund’s commencement of Class D Shares reflects the fees and expenses of Class D Shares, net of any applicable fee and expense limitations or waivers. The bar chart depicts the change in performance from year to year during the periods indicated. The table shows how the Fund’s returns over different periods average out. All figures assume reinvestment of dividends and distributions. For certain periods, the Fund’s performance reflects the effect of expense waivers. Without the effect of these expense waivers, the performance shown would have been lower. The Fund’s past performance does not necessarily indicate how it will perform in the future. Updated performance information is available at janus.com/allfunds or by calling 1-800-525-3713.
Performance Information Illustrates Variability of Returns [Text]	rr_PerformanceInformationIllustratesVariabilityOfReturns	The following information provides some indication of the risks of investing in the Fund by showing how the Fund’s performance has varied over time. The bar chart depicts the change in performance from year to year during the periods indicated.
Performance Availability Phone [Text]	rr_PerformanceAvailabilityPhone	1-800-525-3713
Performance Availability Website Address [Text]	rr_PerformanceAvailabilityWebSiteAddress	janus.com/allfunds
Performance Past Does Not Indicate Future [Text]	rr_PerformancePastDoesNotIndicateFuture	The Fund’s past performance does not necessarily indicate how it will perform in the future.
Bar Chart [Heading]	rr_BarChartHeading	Annual Total Returns for Class D Shares (calendar year-end)
Bar Chart Closing [Text Block]	rr_BarChartClosingTextBlock	Best Quarter:  Fourth Quarter 2006  1.23%          Worst Quarter:  Third Quarter 2011  0.00%
Year to Date Return, Label	rr_YearToDateReturnLabel	The Fund’s year-to-date return as of the calendar quarter ended September 30, 2013 was 0.00%.
Performance Table Heading	rr_PerformanceTableHeading	Average Annual Total Returns (periods ended 12/31/12)
Performance Table Closing [Text Block]	rr_PerformanceTableClosingTextBlock	Updated performance information is available at janus.com/allfunds or by calling 1-800-525-3713.
Money Market Seven Day Yield, Caption [Text]	rr_MoneyMarketSevenDayYieldCaption	The 7-day yield on December 31, 2012 was 0.00% for Janus Money Market Fund.
Money Market Seven Day Yield	rr_MoneyMarketSevenDayYield	0.00%
Janus Money Market Fund | Class D Shares | Class D
Risk/Return:	rr_RiskReturnAbstract
Operating Expenses Column [Text]	rr_OperatingExpensesColumnName	Class D
Management Fees	rr_ManagementFeesOverAssets	0.20%
Other Expenses	rr_OtherExpensesOverAssets	0.47%
Total Annual Fund Operating Expenses	rr_ExpensesOverAssets	0.67%
Expense Example, By Year, Column [Text]	rr_ExpenseExampleByYearColumnName	Class D Shares
1 Year	rr_ExpenseExampleYear01	$ 68
3 Years	rr_ExpenseExampleYear03	214
5 Years	rr_ExpenseExampleYear05	373
10 Years	rr_ExpenseExampleYear10	$ 835
2003	rr_AnnualReturn2003	0.71%
2004	rr_AnnualReturn2004	0.93%
2005	rr_AnnualReturn2005	2.77%
2006	rr_AnnualReturn2006	4.60%
2007	rr_AnnualReturn2007	4.86%
2008	rr_AnnualReturn2008	2.09%
2009	rr_AnnualReturn2009	0.07%
2010	rr_AnnualReturn2010	0.01%
2011	rr_AnnualReturn2011	0.01%
2012	rr_AnnualReturn2012	0.00%
Bar Chart, Year to Date Return, Date	rr_BarChartYearToDateReturnDate	Sep. 30, 2013
Bar Chart, Year to Date Return	rr_BarChartYearToDateReturn	0.00%
Highest Quarterly Return, Label	rr_HighestQuarterlyReturnLabel	Best Quarter:
Highest Quarterly Return, Date	rr_BarChartHighestQuarterlyReturnDate	Dec. 31, 2006
Highest Quarterly Return	rr_BarChartHighestQuarterlyReturn	1.23%
Lowest Quarterly Return, Label	rr_LowestQuarterlyReturnLabel	Worst Quarter:
Lowest Quarterly Return, Date	rr_BarChartLowestQuarterlyReturnDate	Sep. 30, 2011
Lowest Quarterly Return	rr_BarChartLowestQuarterlyReturn	0.00%
Janus Money Market Fund | Class D Shares | Return Before Taxes | Class D
Risk/Return:	rr_RiskReturnAbstract
Column	rr_AverageAnnualReturnColumnName	Class D Shares
Label	rr_AverageAnnualReturnLabel	Return Before Taxes
1 Year	rr_AverageAnnualReturnYear01	none
5 Years	rr_AverageAnnualReturnYear05	0.43%
10 Years	rr_AverageAnnualReturnYear10	1.59%
Since Inception	rr_AverageAnnualReturnSinceInception	2.91%
Inception Date	rr_AverageAnnualReturnInceptionDate	Feb. 14, 1995

XML

Janus Short-Term Bond Fund | Class A, C, S, I, N, T Shares

FUND SUMMARY

Janus Short-Term Bond Fund

INVESTMENT OBJECTIVE

Janus Short-Term Bond Fund seeks as high a level of current income as is consistent with preservation of capital.

FEES AND EXPENSES OF THE FUND

This table describes the fees and expenses that you may pay if you buy and hold Shares of the Fund. Each share class has different expenses, but represents an investment in the same Fund.

For Class A Shares, you may qualify for sales charge discounts if you and your family invest, or agree to invest in the future, at least $50,000 in the Fund or in other Janus mutual funds. More information about these and other discounts, as well as eligibility requirements for each share class, is available from your financial professional and in the “Purchases” section on page 64 of the Fund’s Prospectus and in the “Purchases” section on page 70 of the Fund’s Statement of Additional Information.

SHAREHOLDER FEES
(fees paid directly from your investment)

Shareholder Fees Janus Short-Term Bond Fund Class A, C, S, I, N, T Shares	Class A	Class C	Class S	Class I	Class N	Class T
Shareholder Fees Column [Text]	Class A	Class C	Class S	Class I	Class N	Class T
Maximum Sales Charge (load) Imposed on Purchases (as a percentage of offering price)	2.50%	none	none	none	none	none
Maximum Deferred Sales Charge (load) (as a percentage of the lower of original purchase price or redemption proceeds)	none	1.00%	none	none	none	none

ANNUAL FUND OPERATING EXPENSES
(expenses that you pay each year as a percentage of the value of your investment)

Annual Fund Operating Expenses Janus Short-Term Bond Fund Class A, C, S, I, N, T Shares		Class A	Class C	Class S	Class I	Class N	Class T
Operating Expenses Column [Text]		Class A	Class C	Class S	Class I	Class N	Class T
Management Fees		0.55%	0.55%	0.55%	0.55%	0.55%	0.55%
Distribution/Service (12b-1) Fees		0.25%	1.00%	0.25%	none	none	none
Other Expenses		0.15%	0.14%	0.30%	0.11%	0.05%	0.30%
Total Annual Fund Operating Expenses	[1]	0.95%	1.69%	1.10%	0.66%	0.60%	0.85%
Fee Waiver	[1]	0.15%	0.14%	0.11%	0.12%	0.11%	0.11%
Total Annual Fund Operating Expenses After Fee Waiver	[1]	0.80%	1.55%	0.99%	0.54%	0.49%	0.74%

EXAMPLE:

The following Example is based on expenses without waivers. The Example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds.

The Example assumes that you invest $10,000 in the Fund for the time periods indicated and reinvest all dividends and distributions. The Example also assumes that your investment has a 5% return each year and that the Fund’s operating expenses without waivers remain the same. Although your actual costs may be higher or lower, based on these assumptions your costs would be:

If Shares are redeemed:

Expense Example Janus Short-Term Bond Fund Class A, C, S, I, N, T Shares (USD $)	Expense Example, By Year, Column [Text]	1 Year	3 Years	5 Years	10 Years
Class A	Class A Shares	345	545	762	1,387
Class C	Class C Shares	272	533	918	1,998
Class S	Class S Shares	112	350	606	1,340
Class I	Class I Shares	67	211	368	822
Class N	Class N Shares	61	192	335	750
Class T	Class T Shares	87	271	471	1,049

If Shares are not redeemed:

Expense Example, No Redemption Janus Short-Term Bond Fund Class A, C, S, I, N, T Shares (USD $)	Expense Example, No Redemption, By Year, Column [Text]	1 Year	3 Years	5 Years	10 Years
Class A	Class A Shares	345	545	762	1,387
Class C	Class C Shares	172	533	918	1,998
Class S	Class S Shares	112	350	606	1,340
Class I	Class I Shares	67	211	368	822
Class N	Class N Shares	61	192	335	750
Class T	Class T Shares	87	271	471	1,049

Portfolio Turnover:

The Fund pays transaction costs, such as commissions, when it buys and sells securities (or “turns over” its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when Fund shares are held in a taxable account. These costs, which are not reflected in annual fund operating expenses or in the Example, affect the Fund’s performance. During the most recent fiscal year, the Fund’s portfolio turnover rate was 100% of the average value of its portfolio.

PRINCIPAL INVESTMENT STRATEGIES

The Fund invests, under normal circumstances, at least 80% of its net assets in short- and intermediate-term securities such as corporate bonds or notes or government securities, including agency securities. The Fund may invest up to 35% of its net assets in high-yield/high-risk bonds, also known as “junk” bonds. The Fund expects to maintain an average-weighted effective maturity of three years or less under normal circumstances. As of June 30, 2013, the Fund’s weighted average maturity was 2.5 years. The Fund may also invest in bank loans, mortgage-backed securities, asset-backed securities, and foreign debt securities (which may include investments in emerging markets). Due to the nature of securities in which the Fund invests, it may have relatively high portfolio turnover compared to other funds.

“Effective” maturity differs from actual maturity, which may be longer. In calculating the “effective” maturity the portfolio managers will estimate the effect of expected principal payments and call provisions on securities held in the portfolio. This gives the portfolio managers some additional flexibility in the securities they purchase, but all else being equal, could result in more volatility than if the Fund calculated an actual maturity target.

In addition, the Fund may invest its assets in derivatives, which are instruments that have a value derived from, or directly linked to, an underlying asset, such as equity securities, fixed-income securities, commodities, currencies, interest rates, or market indices. In particular, the Fund may use derivatives to manage portfolio risk or to manage the effective maturity of the securities in the Fund’s portfolio. The Fund’s exposure to derivatives will vary. For purposes of meeting its 80% investment policy, the Fund may include derivatives that have characteristics similar to the securities in which the Fund may directly invest.

In addition to considering economic factors such as the effect of interest rates on the Fund’s investments, the portfolio managers apply a “bottom up” approach in choosing investments. This means that the portfolio managers look at income-producing securities one at a time to determine if a security is an attractive investment opportunity and if it is consistent with the Fund’s investment policies.

The Fund may lend portfolio securities on a short-term or long-term basis, in an amount equal to up to 1/3 of its total assets as determined at the time of the loan origination.

PRINCIPAL INVESTMENT RISKS

Although the Fund may be less volatile than funds that invest most of their assets in common stocks, the Fund’s returns and yields will vary, and you could lose money.

Fixed-Income Securities Risk. The Fund invests in a variety of fixed-income securities. Typically, the values of fixed-income securities change inversely with prevailing interest rates. Therefore, a fundamental risk of fixed-income securities is interest rate risk, which is the risk that the value of such securities will generally decline as prevailing interest rates rise, which may cause the Fund’s net asset value to likewise decrease. How specific fixed-income securities may react to changes in interest rates will depend on the specific characteristics of each security. Fixed-income securities are also subject to credit risk, prepayment risk, valuation risk, and liquidity risk. Credit risk is the risk that the credit strength of an issuer of a fixed-income security will weaken and/or that the issuer will be unable to make timely principal and interest payments and that the security may go into default. Prepayment risk is the risk that during periods of falling interest rates, certain fixed-income securities with higher interest rates, such as mortgage- and asset-backed securities, may be prepaid by their issuers thereby reducing the amount of interest payments. Valuation risk is the risk that one or more of the fixed-income securities in which the Fund invests are priced differently than the value realized upon such security’s sale. In times of market instability, valuation may be more difficult. Liquidity risk is the risk that fixed-income securities may be difficult or impossible to sell at the time that the portfolio managers would like or at the price the portfolio managers believe the security is currently worth.

Sovereign Debt Risk. The Fund may invest in U.S. and foreign government debt securities (“sovereign debt”). Investments in U.S. sovereign debt are considered low risk. However, investments in non-U.S. sovereign debt can involve a high degree of risk, including the risk that the governmental entity that controls the repayment of sovereign debt may not be willing or able to repay the principal and/or to pay the interest on its sovereign debt in a timely manner. A sovereign debtor’s willingness or ability to satisfy its debt obligation may be affected by various factors including, but not limited to, its cash flow situation, the extent of its foreign currency reserves, the availability of foreign exchange when a payment is due, and the relative size of its debt position in relation to its economy as a whole. In the event of default, there may be limited or no legal remedies for collecting sovereign debt and there may be no bankruptcy proceedings through which the Fund may collect all or part of the sovereign debt that a governmental entity has not repaid.

Foreign Exposure Risk. The Fund may have exposure to foreign markets as a result of its investments in foreign securities, including investments in emerging markets, which can be more volatile than the U.S. markets. As a result, its returns and net asset value may be affected to a large degree by fluctuations in currency exchange rates or political or economic conditions in a particular country. In some foreign markets, there may not be protection against failure by other parties to complete transactions. It may not be possible for the Fund to repatriate capital, dividends, interest, and other income from a particular country or governmental entity. In addition, a market swing in one or more countries or regions where the Fund has invested a significant amount of its assets may have a greater effect on the Fund’s performance than it would in a more geographically diversified portfolio. To the extent the Fund invests in foreign debt securities, such investments are sensitive to changes in interest rates. Additionally, investments in securities of foreign governments involve the risk that a foreign government may not be willing or able to pay interest or repay principal when due. The Fund’s investments in emerging market countries may involve risks greater than, or in addition to, the risks of investing in more developed countries.

Eurozone Risk. A number of countries in the European Union (“EU”) have experienced severe economic and financial difficulties. As a result, financial markets in the EU have been subject to extreme volatility and declines in asset values and liquidity. Responses to these financial problems by European governments, central banks, and others, including austerity measures and reforms, may not work, may result in social unrest, and may limit future growth and economic recovery or have other unintended consequences. Further defaults or restructurings by governments and others of their debt could have additional adverse effects on economies, financial markets, and asset valuations around the world. To the extent that the Fund has exposure to European markets or to transactions tied to the value of the euro, these events could negatively affect the value and liquidity of the Fund’s investments.

Mortgage-Backed Securities Risk. Mortgage-backed securities are classified generally as either commercial mortgage-backed securities or residential mortgage-backed securities, each of which is subject to certain specific risks. Mortgage-backed securities tend to be more sensitive to changes in interest rates than other types of debt securities. Investments in mortgage-backed securities are subject to both extension risk, where borrowers extend the duration of their mortgages in times of rising interest rates, and prepayment risk, where borrowers pay off their mortgages sooner than expected in times of declining interest rates. These risks may reduce the Fund’s returns. In addition, investments in mortgage-backed securities, including those comprised of subprime mortgages, may be subject to a higher degree of credit risk, valuation risk, and liquidity risk than various other types of fixed-income securities.

Bank Loan Risk. Bank loans are obligations of companies or other entities entered into in connection with recapitalizations, acquisitions, and refinancings. The Fund’s investments in bank loans are generally acquired as a participation interest in, or assignment of, loans originated by a lender or other financial institution. These investments may include institutionally-traded floating and fixed-rate debt securities. Participation interests and assignments involve credit, interest rate, and liquidity risk. In addition, the bank loans underlying these securities often involve borrowers with low credit ratings whose financial conditions are troubled or uncertain, including companies that are highly leveraged or in bankruptcy proceedings.

High-Yield/High-Risk Bond Risk. High-yield/high-risk bonds may be more sensitive than other types of bonds to economic changes, political changes, or adverse developments specific to the company that issued the bond, which may adversely affect their value.

Portfolio Turnover Risk. Increased portfolio turnover may result in higher costs, which may have a negative effect on the Fund’s performance. In addition, higher portfolio turnover may result in the acceleration of capital gains and the recognition of greater levels of short-term capital gains, which are taxed at ordinary federal income tax rates when distributed to shareholders.

Derivatives Risk. Derivatives can be highly volatile and involve risks in addition to the risks of the underlying referenced securities. Gains or losses from a derivative investment can be substantially greater than the derivative’s original cost, and can therefore involve leverage. Leverage may cause the Fund to be more volatile than if it had not used leverage. Derivatives can be less liquid than other types of investments and entail the risk that the counterparty will default on its payment obligations.

Securities Lending Risk. The Fund may seek to earn additional income through lending its securities to certain qualified broker-dealers and institutions. There is the risk that when portfolio securities are lent, the securities may not be returned on a timely basis, and the Fund may experience delays and costs in recovering the security or gaining access to the collateral provided to the Fund to collateralize the loan. If the Fund is unable to recover a security on loan, the Fund may use the collateral to purchase replacement securities in the market. There is a risk that the value of the collateral could decrease below the cost of the replacement security by the time the replacement investment is made, resulting in a loss to the Fund.

An investment in the Fund is not a bank deposit and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency.

PERFORMANCE INFORMATION

The following information provides some indication of the risks of investing in the Fund by showing how the Fund’s performance has varied over time. Class T Shares (formerly named Class J Shares, the initial share class) of the Fund commenced operations with the Fund’s inception. Class A Shares, Class C Shares, Class S Shares, and Class I Shares of the Fund commenced operations on July 6, 2009. Class N Shares of the Fund commenced operations on May 31, 2012.

• The performance shown for Class T Shares is calculated using the fees and expenses of Class T Shares in effect during the periods shown, net of any applicable fee and expense limitations or waivers.
• The performance shown for Class A Shares, Class C Shares, Class S Shares, and Class I Shares for periods prior to July 6, 2009, reflects the performance of the Fund’s former Class J Shares, calculated using the fees and expenses of each respective share class, without the effect of any fee and expense limitations or waivers.
• The performance shown for Class N Shares for periods prior to May 31, 2012, reflects the performance of the Fund’s Class T Shares, calculated using the fees and expenses of Class T Shares, net of any applicable fee and expense limitations or waivers.

If Class A Shares, Class C Shares, Class S Shares, and Class I Shares of the Fund had been available during periods prior to July 6, 2009, or Class N Shares of the Fund had been available during periods prior to May 31, 2012, the performance shown for each respective share class may have been different. The performance shown for periods following the Fund’s commencement of Class A Shares, Class C Shares, Class S Shares, Class I Shares, and Class N Shares reflects the fees and expenses of each respective share class, net of any applicable fee and expense limitations or waivers.

The bar chart depicts the change in performance from year to year during the periods indicated. The bar chart figures do not include any applicable sales charges that an investor may pay when they buy or sell Class A Shares or Class C Shares of the Fund. If sales charges were included, the returns would be lower. The table compares the Fund’s average annual returns for the periods indicated to a broad-based securities market index. The index is not actively managed and is not available for direct investment. All figures assume reinvestment of dividends and distributions. For certain periods, the Fund’s performance reflects the effect of expense waivers. Without the effect of these expense waivers, the performance shown would have been lower.

The Fund’s past performance (before and after taxes) does not necessarily indicate how it will perform in the future. Updated performance information is available at janus.com/advisor/mutual-funds or by calling 1-877-335-2687.

Annual Total Returns for Class T Shares (calendar year-end)

Best Quarter:  Second Quarter 2009  3.18%          Worst Quarter:  Second Quarter 2008  −0.90%

The Fund’s year-to-date return as of the calendar quarter ended September 30, 2013 was 0.71%.

Average Annual Total Returns (periods ended 12/31/12)

Average Annual Total Returns Janus Short-Term Bond Fund Class A, C, S, I, N, T Shares	Column	Label		1 Year	5 Years	10 Years	Since Inception	Inception Date
Class T Return Before Taxes	Class T Shares	Return Before Taxes		3.42%	4.24%	3.80%	4.58%	Sep. 01, 1992
Class T Return After Taxes on Distributions	Class T Shares	Return After Taxes on Distributions		2.65%	3.23%	2.67%	2.90%	Sep. 01, 1992
Class T Return After Taxes on Distributions and Sale of Fund Shares	Class T Shares	Return After Taxes on Distributions and Sale of Fund Shares		2.31%	3.06%	2.60%	2.88%	Sep. 01, 1992
Class A Return Before Taxes	Class A Shares	Return Before Taxes	[1]	0.78%	3.15%	3.01%	3.96%	Sep. 01, 1992
Class C Return Before Taxes	Class C Shares	Return Before Taxes	[2]	1.67%	3.54%	2.89%	3.53%	Sep. 01, 1992
Class S Return Before Taxes	Class S Shares	Return Before Taxes		3.23%	3.81%	3.27%	4.01%	Sep. 01, 1992
Class I Return Before Taxes	Class I Shares	Return Before Taxes		3.68%	4.24%	3.72%	4.43%	Sep. 01, 1992
Class N Return Before Taxes	Class N Shares	Return Before Taxes		3.42%	4.24%	3.80%	4.58%	Sep. 01, 1992
Barclays 1-3 Year U.S. Government/Credit Index (reflects no deduction for expenses, fees, or taxes)		Barclays 1-3 Year U.S. Government/Credit Index		1.26%	2.88%	3.13%	4.62%	Sep. 01, 1992

After-tax returns are calculated using distributions for the Fund’s Class T Shares (formerly named Class J Shares, the initial share class). After-tax returns are calculated using the historically highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes. Actual after-tax returns depend on your individual tax situation and may differ from those shown in the preceding table. The after-tax return information shown above does not apply to Fund shares held through a tax-deferred account, such as a 401(k) plan or an IRA.

After-tax returns are only shown for Class T Shares of the Fund. After-tax returns for the other classes of Shares will vary from those shown for Class T Shares due to varying sales charges (as applicable), fees, and expenses among the classes.

[1] Janus Capital has contractually agreed to waive its investment advisory fee and/or reimburse Fund expenses to the extent that the Fund’s total annual fund operating expenses (excluding the distribution and shareholder servicing fees – applicable to Class A Shares, Class C Shares, and Class S Shares; administrative services fees payable pursuant to the Transfer Agency Agreement; brokerage commissions; interest; dividends; taxes; acquired fund fees and expenses; and extraordinary expenses) exceed 0.49% until at least November 1, 2014. The contractual waiver may be terminated or modified prior to this date only at the discretion of the Board of Trustees.

[1] Calculated assuming maximum permitted sales loads.

[2] The one year return is calculated to include the contingent deferred sales charge.

XML

Label

Element

Value

Risk/Return:

rr_RiskReturnAbstract

Registrant Name

dei_EntityRegistrantName

JANUS INVESTMENT FUND

Prospectus Date

rr_ProspectusDate

Oct. 28, 2013

Janus Money Market Fund | Class T Shares

Risk/Return:

rr_RiskReturnAbstract

Risk/Return [Heading]

rr_RiskReturnHeading

FUND SUMMARY

Janus Money Market Fund

Objective [Heading]

rr_ObjectiveHeading

INVESTMENT OBJECTIVES

Objective, Primary [Text Block]

rr_ObjectivePrimaryTextBlock

Janus Money Market Fund seeks capital preservation and liquidity with current income as a secondary objective.

Expense [Heading]

rr_ExpenseHeading

FEES AND EXPENSES OF THE FUND

Expense Narrative [Text Block]

rr_ExpenseNarrativeTextBlock

This table describes the fees and expenses that you may pay if you buy and hold Shares of the Fund.

Operating Expenses Caption [Text]

rr_OperatingExpensesCaption

ANNUAL FUND OPERATING EXPENSES
(expenses that you pay each year as a percentage of the value of your investment)

Expense Example [Heading]

rr_ExpenseExampleHeading

EXAMPLE:

Expense Example by Year [Heading]

rr_ExpenseExampleByYearHeading

The Example assumes that you invest $10,000 in the Fund for the time periods indicated, reinvest all dividends and distributions, and then redeem all of your Shares at the end of each period. The Example also assumes that your investment has a 5% return each year and that the Fund’s operating expenses remain the same. Although your actual costs may be higher or lower, based on these assumptions your costs would be:

Expense Example Narrative [Text Block]

rr_ExpenseExampleNarrativeTextBlock

The Example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds.

Strategy [Heading]

rr_StrategyHeading

PRINCIPAL INVESTMENT STRATEGIES

Strategy Narrative [Text Block]

rr_StrategyNarrativeTextBlock

The Fund pursues its investment objectives by investing primarily in high quality debt obligations and obligations of financial institutions. Debt obligations may include commercial paper, notes and bonds, and variable amount master demand notes. Obligations of financial institutions include certificates of deposit and time deposits. The Fund also intends to invest in repurchase agreements including those secured by U.S. Government agencies. Some government agencies backed by the full faith and credit of the United States are supported by the issuer’s ability to borrow from the United States Treasury, some are supported only by the credit of the issuer, and some are supported by the United States in some other way.

The Fund will:

• invest in high quality, short-term money market instruments that present minimal credit risks, as determined by Janus Capital

• invest only in U.S. dollar-denominated instruments that have a remaining maturity of 397 days or less (as calculated pursuant to Rule 2a-7 under the Investment Company Act of 1940, as amended)

• maintain a dollar-weighted average portfolio maturity of 60 days or less and maintain a dollar-weighted average portfolio life (portfolio maturity measured without reference to any maturity shortening provisions of adjustable rate securities by reference to their interest rate reset dates) of 120 days or less

Risk [Heading]

rr_RiskHeading

PRINCIPAL INVESTMENT RISKS

Risk Narrative [Text Block]

rr_RiskNarrativeTextBlock

Market Risk. The Fund’s yield will vary as the short-term securities in its portfolio mature and the proceeds are reinvested in securities with different interest rates. For capital preservation and liquidity, the Fund may have a greater concentration in short-term securities including, but not limited to, investing up to all of its assets in overnight securities, which may result in a reduction of the Fund’s yield. Over time, the real value of the Fund’s yield may be eroded by inflation. Although the Fund invests only in high-quality, short-term money market instruments, there is a risk that the value of the securities it holds will fall as a result of changes in interest rates, an issuer’s actual or perceived creditworthiness, or an issuer’s ability to meet its obligations. The credit quality of the Fund’s holdings can change rapidly in certain market environments and any downgrade or default of a portfolio security could cause the Fund’s share price or yield to fall.

Collateral Risk. With respect to collateral received in repurchase transactions or other investments, the Fund may have significant exposure to financial services, mortgage markets, and government agencies not secured by the full faith and credit of the United States. Such exposure, depending on market conditions, could have a negative impact on the Fund, including minimizing the value of any collateral.

Money Market Risk. An investment in the Fund is not a bank deposit and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency. Although the Fund seeks to preserve the value of your investment at $1.00 per share, it is possible to lose money by investing in the Fund.

Risk Money Market Fund [Text]

rr_RiskMoneyMarketFund

Money Market Risk. An investment in the Fund is not a bank deposit and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency. Although the Fund seeks to preserve the value of your investment at $1.00 per share, it is possible to lose money by investing in the Fund.

Bar Chart and Performance Table [Heading]

rr_BarChartAndPerformanceTableHeading

PERFORMANCE INFORMATION

Performance Narrative [Text Block]

rr_PerformanceNarrativeTextBlock

The following information provides some indication of the risks of investing in the Fund by showing how the Fund’s performance has varied over time. Class T Shares (formerly named Class J Shares, the initial share class) of the Fund commenced operations with the Fund’s inception. The performance shown for Class T Shares is calculated using the fees and expenses of Class T Shares in effect during the periods shown, net of any applicable fee and expense limitations or waivers.

The bar chart depicts the change in performance from year to year during the periods indicated. The table shows how the Fund’s returns over different periods average out. All figures assume reinvestment of dividends and distributions. For certain periods, the Fund’s performance reflects the effect of expense waivers. Without the effect of these expense waivers, the performance shown would have been lower.

The Fund’s past performance does not necessarily indicate how it will perform in the future. Updated performance information is available at janus.com/advisor/mutual-funds or by calling 1-877-335-2687.

Performance Information Illustrates Variability of Returns [Text]

rr_PerformanceInformationIllustratesVariabilityOfReturns

The following information provides some indication of the risks of investing in the Fund by showing how the Fund’s performance has varied over time.

The bar chart depicts the change in performance from year to year during the periods indicated.

Performance Availability Phone [Text]

rr_PerformanceAvailabilityPhone

1-877-335-2687

Performance Availability Website Address [Text]

rr_PerformanceAvailabilityWebSiteAddress

janus.com/advisor/mutual-funds

Performance Past Does Not Indicate Future [Text]

rr_PerformancePastDoesNotIndicateFuture

The Fund’s past performance does not necessarily indicate how it will perform in the future.

Bar Chart [Heading]

rr_BarChartHeading

Annual Total Returns for Class T Shares (calendar year-end)

Bar Chart Closing [Text Block]

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Best Quarter:  Fourth Quarter  2006  1.23%          Worst Quarter:  Third Quarter 2011  0.00%

Year to Date Return, Label

rr_YearToDateReturnLabel

The Fund’s year-to-date return as of the calendar quarter ended September 30, 2013 was 0.00%.

Performance Table Heading

rr_PerformanceTableHeading

Average Annual Total Returns (periods ended 12/31/12)

Performance Table Closing [Text Block]

rr_PerformanceTableClosingTextBlock

Updated performance information is available at janus.com/advisor/mutual-funds or by calling 1-877-335-2687.

Money Market Seven Day Yield, Caption [Text]

rr_MoneyMarketSevenDayYieldCaption

The 7-day yield on December 31, 2012 was 0.00% for Janus Money Market Fund.

Money Market Seven Day Yield

rr_MoneyMarketSevenDayYield

0.00%

Janus Money Market Fund | Class T Shares | Class T

Risk/Return:

rr_RiskReturnAbstract

Operating Expenses Column [Text]

rr_OperatingExpensesColumnName

Class T

Management Fees

rr_ManagementFeesOverAssets

0.20%

Other Expenses

rr_OtherExpensesOverAssets

0.49%

Total Annual Fund Operating Expenses

rr_ExpensesOverAssets

0.69%

Expense Example, By Year, Column [Text]

rr_ExpenseExampleByYearColumnName

Class T Shares

1 Year

rr_ExpenseExampleYear01

$ 70

3 Years

rr_ExpenseExampleYear03

221

5 Years

rr_ExpenseExampleYear05

384

10 Years

rr_ExpenseExampleYear10

$ 859

2003

rr_AnnualReturn2003

0.71%

2004

rr_AnnualReturn2004

0.93%

2005

rr_AnnualReturn2005

2.77%

2006

rr_AnnualReturn2006

4.60%

2007

rr_AnnualReturn2007

4.86%

2008

rr_AnnualReturn2008

2.09%

2009

rr_AnnualReturn2009

0.07%

2010

rr_AnnualReturn2010

0.01%

2011

rr_AnnualReturn2011

0.01%

2012

rr_AnnualReturn2012

0.00%

Bar Chart, Year to Date Return, Date

rr_BarChartYearToDateReturnDate

Sep. 30, 2013

Bar Chart, Year to Date Return

rr_BarChartYearToDateReturn

0.00%

Highest Quarterly Return, Label

rr_HighestQuarterlyReturnLabel

Best Quarter:

Highest Quarterly Return, Date

rr_BarChartHighestQuarterlyReturnDate

Dec. 31, 2006

Highest Quarterly Return

rr_BarChartHighestQuarterlyReturn

1.23%

Lowest Quarterly Return, Label

rr_LowestQuarterlyReturnLabel

Worst Quarter:

Lowest Quarterly Return, Date

rr_BarChartLowestQuarterlyReturnDate

Sep. 30, 2011

Lowest Quarterly Return

rr_BarChartLowestQuarterlyReturn

0.00%

Janus Money Market Fund | Class T Shares | Return Before Taxes | Class T

Risk/Return:

rr_RiskReturnAbstract

Column

rr_AverageAnnualReturnColumnName

Class T Shares

Label

rr_AverageAnnualReturnLabel

Return Before Taxes

1 Year

rr_AverageAnnualReturnYear01

none

5 Years

rr_AverageAnnualReturnYear05

0.43%

10 Years

rr_AverageAnnualReturnYear10

1.59%

Since Inception

rr_AverageAnnualReturnSinceInception

2.91%

Inception Date

rr_AverageAnnualReturnInceptionDate

Feb. 14, 1995

XML

Janus Real Return Fund | Class A, C, S, I, T Shares

FUND SUMMARY

Janus Real Return Fund

INVESTMENT OBJECTIVE

Janus Real Return Fund seeks real return consistent with preservation of capital.

FEES AND EXPENSES OF THE FUND

This table describes the fees and expenses that you may pay if you buy and hold Shares of the Fund. Each share class has different expenses, but represents an investment in the same Fund.

For Class A Shares, you may qualify for sales charge discounts if you and your family invest, or agree to invest in the future, at least $50,000 in the Fund or in other Janus mutual funds. More information about these and other discounts, as well as eligibility requirements for each share class, is available from your financial professional and in the “Purchases” section on page 64 of the Fund’s Prospectus and in the “Purchases” section on page 70 of the Fund’s Statement of Additional Information.

SHAREHOLDER FEES
(fees paid directly from your investment)

Shareholder Fees Janus Real Return Fund Class A, C, S, I, T Shares	Class A	Class C	Class S	Class I	Class T
Shareholder Fees Column [Text]	Class A	Class C	Class S	Class I	Class T
Maximum Sales Charge (load) Imposed on Purchases (as a percentage of offering price)	4.75%	none	none	none	none
Maximum Deferred Sales Charge (load) (as a percentage of the lower of original purchase price or redemption proceeds)	none	1.00%	none	none	none

ANNUAL FUND OPERATING EXPENSES
(expenses that you pay each year as a percentage of the value of your investment)

Annual Fund Operating Expenses Janus Real Return Fund Class A, C, S, I, T Shares		Class A	Class C	Class S	Class I	Class T
Operating Expenses Column [Text]		Class A	Class C	Class S	Class I	Class T
Management Fees		0.55%	0.55%	0.55%	0.55%	0.55%
Distribution/Service (12b-1) Fees		0.25%	1.00%	0.25%	none	none
Other Expenses	[1]	2.17%	2.24%	2.38%	2.15%	2.38%
Total Annual Fund Operating Expenses	[2]	2.97%	3.79%	3.18%	2.70%	2.93%
Fee Waiver	[2]	1.96%	2.03%	1.92%	1.94%	1.92%
Total Annual Fund Operating Expenses After Fee Waiver	[2]	1.01%	1.76%	1.26%	0.76%	1.01%

EXAMPLE:

The following Example is based on expenses without waivers. The Example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds.

The Example assumes that you invest $10,000 in the Fund for the time periods indicated and reinvest all dividends and distributions. The Example also assumes that your investment has a 5% return each year and that the Fund’s operating expenses without waivers or recoupments (if applicable) remain the same. Although your actual costs may be higher or lower, based on these assumptions your costs would be:

If Shares are redeemed:

Expense Example Janus Real Return Fund Class A, C, S, I, T Shares (USD $)	Expense Example, By Year, Column [Text]	1 Year	3 Years	5 Years	10 Years
Class A	Class A Shares	761	1,350	1,963	3,608
Class C	Class C Shares	481	1,158	1,953	4,027
Class S	Class S Shares	321	980	1,664	3,485
Class I	Class I Shares	273	838	1,430	3,032
Class T	Class T Shares	296	907	1,543	3,252

If Shares are not redeemed:

Expense Example, No Redemption Janus Real Return Fund Class A, C, S, I, T Shares (USD $)	Expense Example, No Redemption, By Year, Column [Text]	1 Year	3 Years	5 Years	10 Years
Class A	Class A Shares	761	1,350	1,963	3,608
Class C	Class C Shares	381	1,158	1,953	4,027
Class S	Class S Shares	321	980	1,664	3,485
Class I	Class I Shares	273	838	1,430	3,032
Class T	Class T Shares	296	907	1,543	3,252

Portfolio Turnover: 

The Fund pays transaction costs, such as commissions, when it buys and sells securities (or “turns over” its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when Fund shares are held in a taxable account. These costs, which are not reflected in annual fund operating expenses or in the Example, affect the Fund’s performance. During the most recent fiscal year, the Fund’s portfolio turnover rate was 112% of the average value of its portfolio.

PRINCIPAL INVESTMENT STRATEGIES

The Fund pursues its investment objective by primarily investing in U.S. Treasury securities, short-duration high-yield/high-risk debt, commodity-linked investments, and equity securities. The Fund’s investments in U.S. Treasury securities may also include Treasury Inflation-Protected Securities, also known as TIPS. As utilized by the Fund, each of these types of investments may be considered an “inflation-related investment,” which are those that may provide what is known as “real return,” or a rate of return above the rate of inflation over a full market cycle. Due to the nature of securities in which the Fund invests, it may have relatively high portfolio turnover compared to other funds.

The Fund may invest up to 90% of its net assets in short-duration high-yield/high-risk debt securities. The Fund’s investments in short-duration high-yield/high-risk securities include debt rated below investment grade, also known as “junk” bonds. Securities rated below investment grade may include their unrated equivalents or other high-yielding securities the portfolio managers believe offer attractive risk/return characteristics. The Fund may also invest in certain investment grade debt instruments, including corporate bonds, government bonds, municipal bonds, mortgage-backed securities, zero-coupon bonds, and agency securities. The Fund may invest in foreign debt securities.

To seek exposure to the commodities markets, the Fund may invest in commodity-linked investments such as commodity-related exchange-traded funds (“ETFs”), commodity index-linked swap agreements, commodity options and futures, and options on futures that provide exposure to the investment returns of the commodities markets. The Fund may also invest in other commodity-linked derivative instruments, such as commodity-linked notes (“structured notes”).

The Fund’s investments in equity securities may include common stock, preferred stock, and convertible securities, all of which may include exposure to foreign markets. The Fund may invest in companies of any market capitalization. The Fund’s equity investments may also include securities of real estate-related companies, including, but not limited to, real estate investment trusts (“REITs”) and similar REIT-like entities, such as foreign entities that have REIT characteristics.

The Fund may also invest in derivative instruments (by taking long and/or short positions) for various purposes, including hedging by shorting interest rate futures against long positions in TIPS, using inflation index swaps to hedge against unexpected changes in the rate of inflation, using interest rate swaps to hedge against changes in interest rates, using currency swaps to adjust its currency exposure, to increase or decrease the Fund’s exposure to a particular market, to manage or adjust the risk profile of the Fund related to an investment, and to earn income and enhance returns. The Fund’s exposure to derivatives will vary, is not limited to those derivatives listed, and could be significant at times.

The Fund may also use reverse repurchase agreements to generate income as part of its inflation-related strategies. Proceeds from reverse repurchase agreement transactions may be invested in other securities or instruments to attempt to increase the Fund’s investment return. The Fund may also invest in money market instruments, buy backs or dollar rolls, other securitized debt products, bank loans, various when-issued securities, exchange-traded notes, and other investment companies.

In addition to considering economic factors such as the rate of inflation and the effect of interest rates on the Fund’s investments, the portfolio managers apply a “bottom up” approach in choosing investments. This means that the portfolio managers look at securities one at a time to determine if a security is an attractive investment opportunity and if it is consistent with the Fund’s investment policies.

The Fund may lend portfolio securities on a short-term or long-term basis, in an amount equal to up to 1/3 of its total assets as determined at the time of the loan origination.

PRINCIPAL INVESTMENT RISKS

Although the Fund may be less volatile than funds that invest most of their assets in common stocks, the Fund’s returns and yields will vary, and you could lose money.

Fixed-Income Securities Risk. The Fund invests in a variety of fixed-income securities. Typically, the values of fixed-income securities change inversely with prevailing interest rates. Therefore, a fundamental risk of fixed-income securities is interest rate risk, which is the risk that the value of such securities will generally decline as prevailing interest rates rise, which may cause the Fund’s net asset value to likewise decrease. How specific fixed-income securities may react to changes in interest rates will depend on the specific characteristics of each security. Fixed-income securities are also subject to credit risk, prepayment risk, valuation risk, and liquidity risk. Credit risk is the risk that the credit strength of an issuer of a fixed-income security will weaken and/or that the issuer will be unable to make timely principal and interest payments and that the security may go into default. Prepayment risk is the risk that during periods of falling interest rates, certain fixed-income securities with higher interest rates, such as mortgage- and asset-backed securities, may be prepaid by their issuers thereby reducing the amount of interest payments. Valuation risk is the risk that one or more of the fixed-income securities in which the Fund invests are priced differently than the value realized upon such security’s sale. In times of market instability, valuation may be more difficult. Liquidity risk is the risk that fixed-income securities may be difficult or impossible to sell at the time that the portfolio managers would like or at the price the portfolio managers believe the security is currently worth.

High-Yield/High-Risk Bond Risk. The Fund may invest up to 90% of its net assets in higher-yielding/higher-risk bonds, also known as “junk” bonds. High-yield/high-risk bonds may be more sensitive than other types of bonds to economic changes, political changes, or adverse developments specific to the company that issued the bond, which may adversely affect their value.

Sovereign Debt Risk. The Fund may invest in U.S. and foreign government debt securities (“sovereign debt”). Investments in U.S. sovereign debt are considered low risk. However, investments in non-U.S. sovereign debt can involve a high degree of risk, including the risk that the governmental entity that controls the repayment of sovereign debt may not be willing or able to repay the principal and/or to pay the interest on its sovereign debt in a timely manner. A sovereign debtor’s willingness or ability to satisfy its debt obligation may be affected by various factors including, but not limited to, its cash flow situation, the extent of its foreign currency reserves, the availability of foreign exchange when a payment is due, and the relative size of its debt position in relation to its economy as a whole. In the event of default, there may be limited or no legal remedies for collecting sovereign debt and there may be no bankruptcy proceedings through which the Fund may collect all or part of the sovereign debt that a governmental entity has not repaid.

Foreign Exposure Risk. The Fund may have exposure to foreign markets as a result of its investments in foreign securities, including investments in emerging markets, which can be more volatile than the U.S. markets. As a result, its returns and net asset value may be affected to a large degree by fluctuations in currency exchange rates or political or economic conditions in a particular country. In some foreign markets, there may not be protection against failure by other parties to complete transactions. It may not be possible for the Fund to repatriate capital, dividends, interest, and other income from a particular country or governmental entity. In addition, a market swing in one or more countries or regions where the Fund has invested a significant amount of its assets may have a greater effect on the Fund’s performance than it would in a more geographically diversified portfolio. To the extent the Fund invests in foreign debt securities, such investments are sensitive to changes in interest rates. Additionally, investments in securities of foreign governments involve the risk that a foreign government may not be willing or able to pay interest or repay principal when due.

Real Estate Securities Risk. The Fund’s performance may be affected by the risks associated with investments in real estate-related companies. The value of real estate-related companies’ securities is sensitive to changes in real estate values and rental income, property taxes, interest rates, tax and regulatory requirements, supply and demand, and the management skill and creditworthiness of the company. Investments in REITs involve the same risks as other real estate investments. In addition, a REIT could fail to qualify for tax-free pass-through of its income under the Internal Revenue Code or fail to maintain its exemption from registration under the Investment Company Act of 1940, as amended, which could produce adverse economic consequences for the REIT and its investors, including the Fund.

Inflation-Related Investment Risk. Inflation index swaps, inflation-linked bonds (including Treasury Inflation-Protected Securities (“TIPS”)), and other inflation-linked securities are subject to inflation risk. A swap held long by the Fund can potentially lose value if the rate of inflation over the life of the swap is less than the fixed rate that the Fund agrees to pay at the initiation of the swap. Except for the Fund’s investments in TIPS, which are guaranteed as to principal by the U.S. Treasury, the inflation-adjusted principal value of inflation-linked bonds repaid at maturity may be less than the original principal. Because of their inflation-linked adjustment feature, inflation-linked bonds typically have lower yields than conventional fixed-rate securities. In the event of deflation, where prices decline over time, the principal and income of inflation-linked bonds will likely decline, resulting in losses to the Fund.

Commodity-Linked Investments Risk. The Fund may invest in various commodity-linked investments that provide exposure to the commodities markets. Such exposure may subject the Fund to greater volatility than investments in traditional securities. The value of a given commodity-linked derivative investment typically is based upon the price movements of a physical commodity (such as heating oil, livestock, or agricultural products), a commodity futures contract or commodity index, or some other readily measurable economic variable. The value of commodity-linked derivative instruments may therefore be affected by changes in overall market movements, volatility of the underlying benchmark, changes in interest rates, or other factors affecting a particular industry or commodity such as drought, floods, weather, livestock disease, embargoes, tariffs, and international economic, political, and regulatory developments.

Derivatives Risk. Derivatives can be highly volatile and involve risks in addition to the risks of the underlying referenced securities. Gains or losses from a derivative investment can be substantially greater than the derivative’s original cost, and can therefore involve leverage. Leverage may cause the Fund to be more volatile than if it had not used leverage. Derivatives can be complex instruments and may involve analysis that differs from that required for other investment types used by the Fund. If the value of a derivative does not correlate well with the particular market or other asset class to which the derivative is intended to provide exposure, the derivative may not produce the anticipated result. Derivatives can also reduce the opportunity for gain or result in losses by offsetting positive returns in other investments. Derivatives can be less liquid than other types of investments and entail the risk that the counterparty will default on its payment obligations. If the counterparty to a derivative transaction defaults, the Fund would risk the loss of the net amount of the payments that it contractually is entitled to receive. To the extent the Fund enters into short derivative positions, the Fund may be exposed to risks similar to those associated with short sales, including the risk that the Fund’s losses are theoretically unlimited.

Counterparty Risk. Certain derivative and “over-the-counter” instruments, such as swaps and forwards, are subject to the risk that the other party to a contract will not fulfill its contractual obligations.

Exchange-Traded Funds Risk. The Fund may invest in ETFs, which are typically open-end investment companies that are traded on a national securities exchange. ETFs typically incur fees, such as investment advisory fees and other operating expenses that are separate from those of the Fund, which will be indirectly paid by the Fund. As a result, the cost of investing in the Fund may be higher than the cost of investing directly in ETFs and may be higher than other mutual funds that invest directly in stocks and bonds. Further, the price movement of an ETF may fluctuate against the underlying securities or commodities it tracks and may result in a loss. Because the value of ETF shares depends on the demand in the market, the Fund may not be able to purchase or sell an ETF at the most optimal time, which could adversely affect the Fund’s performance.

The ETFs in which the Fund invests are subject to specific risks, depending on the investment strategy of the ETF. In turn, the Fund will be subject to substantially the same risks as those associated with direct exposure to the securities or commodities held by the ETF. Because the Fund may invest in a broad range of ETFs, such risks may include, but are not limited to, leverage risk, foreign exposure risk, and commodities risk.

Mortgage-Backed Securities Risk. Mortgage-backed securities are classified generally as either commercial mortgage-backed securities or residential mortgage-backed securities, each of which is subject to certain specific risks. Mortgage-backed securities tend to be more sensitive to changes in interest rates than other types of debt securities. Investments in mortgage-backed securities are subject to both extension risk, where borrowers extend the duration of their mortgages in times of rising interest rates, and prepayment risk, where borrowers pay off their mortgages sooner than expected in times of declining interest rates. These risks may reduce the Fund’s returns. In addition, investments in mortgage-backed securities, including those comprised of subprime mortgages, may be subject to a higher degree of credit risk, valuation risk, and liquidity risk than various other types of fixed-income securities.

Reverse Repurchase Agreement Risk. Reverse repurchase agreements involve leverage risk, counterparty risk, and the risk that the value of securities that the Fund is obligated to repurchase under the agreement may decline below the repurchase price. When the Fund invests reverse repurchase transaction proceeds, the Fund is at risk for any fluctuations in the value of securities in which the proceeds are invested. To the extent the Fund uses reverse repurchase agreements, the value of an investment in the Fund may be more volatile, and such transactions may increase the Fund’s overall investment exposure. Additionally, interest expenses related to reverse repurchase transactions could exceed the rate of return on debt obligations and other investments held by the Fund, thereby reducing returns to shareholders.

Nondiversification Risk. The Fund is classified as nondiversified under the Investment Company Act of 1940, as amended. This gives the Fund’s portfolio managers more flexibility to hold larger positions in a smaller number of securities. As a result, an increase or decrease in the value of a single security held by the Fund may have a greater impact on the Fund’s net asset value and total return.

Portfolio Turnover Risk. Increased portfolio turnover may result in higher costs, which may have a negative effect on the Fund’s performance. In addition, higher portfolio turnover may result in the acceleration of capital gains and the recognition of greater levels of short-term capital gains, which are taxed at ordinary federal income tax rates when distributed to shareholders.

Securities Lending Risk. The Fund may seek to earn additional income through lending its securities to certain qualified broker-dealers and institutions. There is the risk that when portfolio securities are lent, the securities may not be returned on a timely basis, and the Fund may experience delays and costs in recovering the security or gaining access to the collateral provided to the Fund to collateralize the loan. If the Fund is unable to recover a security on loan, the Fund may use the collateral to purchase replacement securities in the market. There is a risk that the value of the collateral could decrease below the cost of the replacement security by the time the replacement investment is made, resulting in a loss to the Fund.

An investment in the Fund is not a bank deposit and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency.

PERFORMANCE INFORMATION

The following information provides some indication of the risks of investing in the Fund by showing how the Fund’s performance has varied over time. The bar chart depicts the Fund’s performance during the period indicated. The bar chart figures do not include any applicable sales charges that an investor may pay when they buy or sell Class A Shares or Class C Shares of the Fund. If sales charges were included, the returns would be lower. The table compares the Fund’s average annual returns for the periods indicated to broad-based securities market indices. The indices are not actively managed and are not available for direct investment. All figures assume reinvestment of dividends and distributions. For certain periods, the Fund’s performance reflects the effect of expense waivers. Without the effect of these expense waivers, the performance shown would have been lower.

The Fund’s past performance (before and after taxes) does not necessarily indicate how it will perform in the future. Updated performance information is available at janus.com/advisor/mutual-funds or by calling 1-877-335-2687.

Annual Total Returns for Class I Shares (calendar year-end)

Best Quarter:  First Quarter 2012  5.52%          Worst Quarter:  Second Quarter 2012  −3.72%

The Fund’s year-to-date return as of the calendar quarter ended September 30, 2013 was 1.36%.

Average Annual Total Returns (periods ended 12/31/12)

Average Annual Total Returns Janus Real Return Fund Class A, C, S, I, T Shares	Column	Label		1 Year	Since Inception	Inception Date
Class I Return Before Taxes	Class I Shares	Return Before Taxes		4.89%	(0.12%)	May 13, 2011
Class I Return After Taxes on Distributions	Class I Shares	Return After Taxes on Distributions		4.52%	(0.49%)	May 13, 2011
Class I Return After Taxes on Distributions and Sale of Fund Shares	Class I Shares	Return After Taxes on Distributions and Sale of Fund Shares	[1]	3.40%	(0.23%)	May 13, 2011
Class A Return Before Taxes	Class A Shares	Return Before Taxes	[2]	(1.39%)	(3.93%)	May 13, 2011
Class C Return Before Taxes	Class C Shares	Return Before Taxes	[3]	2.80%	(1.14%)	May 13, 2011
Class S Return Before Taxes	Class S Shares	Return Before Taxes		4.48%	(0.60%)	May 13, 2011
Class T Return Before Taxes	Class T Shares	Return Before Taxes		4.67%	(0.34%)	May 13, 2011
Barclays U.S. 1-5 Year TIPS Index (reflects no deduction for expenses, fees, or taxes)		Barclays U.S. 1-5 Year TIPS Index		2.66%	2.44%	May 13, 2011
Consumer Price Index +200 (reflects no deduction for expenses, fees, or taxes)		Consumer Price Index +200		4.02%	2.99%	May 13, 2011
Barclays U.S. TIPS Index (reflects no deduction for expenses, fees, or taxes)		Barclays U.S. TIPS Index		6.98%	9.76%	May 13, 2011
Consumer Price Index +400 (reflects no deduction for expenses, fees, or taxes)		Consumer Price Index +400		6.02%	4.97%	May 13, 2011

Effective October 15, 2012, the Fund’s primary benchmark index changed from the Barclays U.S. TIPS Index to the Barclays U.S. 1-5 Year TIPS Index. Additionally, the Fund changed its secondary benchmark index from the Consumer Price Index +400 to the Consumer Price Index +200. Janus Capital believes that the foregoing benchmark index changes provide a more appropriate representation of the Fund’s investment strategy.

After-tax returns are calculated using the historically highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes. Actual after-tax returns depend on your individual tax situation and may differ from those shown in the preceding table. The after-tax return information shown above does not apply to Fund shares held through a tax-deferred account, such as a 401(k) plan or an IRA.

After-tax returns are only shown for Class I Shares of the Fund. After-tax returns for the other classes of Shares will vary from those shown for Class I Shares due to varying sales charges (as applicable), fees, and expenses among the classes.

[1] Other Expenses are based on the estimated expenses that the Fund expects to incur.

[2] Janus Capital has contractually agreed to waive its investment advisory fee and/or reimburse Fund expenses to the extent that the Fund’s total annual fund operating expenses (excluding the distribution and shareholder servicing fees – applicable to Class A Shares, Class C Shares, and Class S Shares; administrative services fees payable pursuant to the Transfer Agency Agreement; brokerage commissions; interest; dividends; taxes; acquired fund fees and expenses; and extraordinary expenses) exceed 0.76% until at least November 1, 2014. The contractual waiver may be terminated or modified prior to this date only at the discretion of the Board of Trustees. For a period of three years subsequent to the Fund’s commencement of operations (May 13, 2011) or until the Fund’s assets exceed the first breakpoint in the investment advisory fee schedule that was effective at commencement of operations, whichever occurs first, Janus Capital may recover from the Fund fees and expenses previously waived or reimbursed, which could then be considered a deferral, if the Fund’s expense ratio, including recovered expenses, falls below the expense limit.

[1] If the Fund incurs a loss, which generates a tax benefit, the Return After Taxes on Distributions and Sale of Fund Shares may exceed the Fund’s other return figures.

[2] Calculated assuming maximum permitted sales loads.

[3] The one year return is calculated to include the contingent deferred sales charge.

XML

Label	Element	Value
Risk/Return:	rr_RiskReturnAbstract
Registrant Name	dei_EntityRegistrantName	JANUS INVESTMENT FUND
Prospectus Date	rr_ProspectusDate	Oct. 28, 2013
Janus Flexible Bond Fund | Class D Shares
Risk/Return:	rr_RiskReturnAbstract
Risk/Return [Heading]	rr_RiskReturnHeading	FUND SUMMARY Janus Flexible Bond Fund
Objective [Heading]	rr_ObjectiveHeading	INVESTMENT OBJECTIVE
Objective, Primary [Text Block]	rr_ObjectivePrimaryTextBlock	Janus Flexible Bond Fund seeks to obtain maximum total return, consistent with preservation of capital.
Expense [Heading]	rr_ExpenseHeading	FEES AND EXPENSES OF THE FUND
Expense Narrative [Text Block]	rr_ExpenseNarrativeTextBlock	This table describes the fees and expenses that you may pay if you buy and hold Shares of the Fund.
Operating Expenses Caption [Text]	rr_OperatingExpensesCaption	ANNUAL FUND OPERATING EXPENSES (expenses that you pay each year as a percentage of the value of your investment)
Portfolio Turnover [Heading]	rr_PortfolioTurnoverHeading	Portfolio Turnover:
Portfolio Turnover [Text Block]	rr_PortfolioTurnoverTextBlock	The Fund pays transaction costs, such as commissions, when it buys and sells securities (or “turns over” its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when Fund shares are held in a taxable account. These costs, which are not reflected in annual fund operating expenses or in the Example, affect the Fund’s performance. During the most recent fiscal year, the Fund’s portfolio turnover rate was 118% of the average value of its portfolio.
Portfolio Turnover, Rate	rr_PortfolioTurnoverRate	118.00%
Expense Example [Heading]	rr_ExpenseExampleHeading	EXAMPLE:
Expense Example by Year [Heading]	rr_ExpenseExampleByYearHeading	The Example assumes that you invest $10,000 in the Fund for the time periods indicated, reinvest all dividends and distributions, and then redeem all of your Shares at the end of each period. The Example also assumes that your investment has a 5% return each year and that the Fund’s operating expenses remain the same. Although your actual costs may be higher or lower, based on these assumptions your costs would be:
Expense Example Narrative [Text Block]	rr_ExpenseExampleNarrativeTextBlock	The Example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds.
Strategy [Heading]	rr_StrategyHeading	PRINCIPAL INVESTMENT STRATEGIES
Strategy Narrative [Text Block]	rr_StrategyNarrativeTextBlock	The Fund pursues its investment objective by primarily investing, under normal circumstances, at least 80% of its net assets in bonds. Bonds include, but are not limited to, government notes and bonds, corporate bonds, convertible bonds, commercial and residential mortgage-backed securities, and zero-coupon bonds. The Fund will invest at least 65% of its assets in investment grade debt securities. As of June 30, 2013, the Fund’s weighted average maturity was 6.9 years. The Fund will limit its investment in high-yield/high-risk bonds, also known as “junk” bonds, to 35% or less of its net assets. The Fund generates total return from a combination of current income and capital appreciation, but income is usually the dominant portion. The Fund may also invest in asset-backed securities, money market instruments, bank loans, and foreign debt securities (which may include investments in emerging markets). Due to the nature of the securities in which the Fund invests, it may have relatively high portfolio turnover compared to other Funds. In addition, the Fund may invest its assets in derivatives, which are instruments that have a value derived from, or directly linked to, an underlying asset, such as equity securities, fixed-income securities, commodities, currencies, interest rates, or market indices. In particular, the Fund may use interest rate futures to manage portfolio risk. The Fund’s exposure to derivatives will vary. For purposes of meeting its 80% investment policy, the Fund may include derivatives that have characteristics similar to the securities in which the Fund may directly invest. In addition to considering economic factors such as the effect of interest rates on the Fund’s investments, the portfolio managers apply a “bottom up” approach in choosing investments. This means that the portfolio managers look at income-producing securities one at a time to determine if a security is an attractive investment opportunity and if it is consistent with the Fund’s investment policies. The Fund may lend portfolio securities on a short-term or long-term basis, in an amount equal to up to 1/3 of its total assets as determined at the time of the loan origination.
Risk [Heading]	rr_RiskHeading	PRINCIPAL INVESTMENT RISKS
Risk Narrative [Text Block]	rr_RiskNarrativeTextBlock	Although the Fund may be less volatile than funds that invest most of their assets in common stocks, the Fund’s returns and yields will vary, and you could lose money. Fixed-Income Securities Risk. The Fund invests in a variety of fixed-income securities. Typically, the values of fixed-income securities change inversely with prevailing interest rates. Therefore, a fundamental risk of fixed-income securities is interest rate risk, which is the risk that the value of such securities will generally decline as prevailing interest rates rise, which may cause the Fund’s net asset value to likewise decrease. How specific fixed-income securities may react to changes in interest rates will depend on the specific characteristics of each security. Fixed-income securities are also subject to credit risk, prepayment risk, valuation risk, and liquidity risk. Credit risk is the risk that the credit strength of an issuer of a fixed-income security will weaken and/or that the issuer will be unable to make timely principal and interest payments and that the security may go into default. Prepayment risk is the risk that during periods of falling interest rates, certain fixed-income securities with higher interest rates, such as mortgage- and asset-backed securities, may be prepaid by their issuers thereby reducing the amount of interest payments. Valuation risk is the risk that one or more of the fixed-income securities in which the Fund invests are priced differently than the value realized upon such security’s sale. In times of market instability, valuation may be more difficult. Liquidity risk is the risk that fixed-income securities may be difficult or impossible to sell at the time that the portfolio managers would like or at the price the portfolio managers believe the security is currently worth. Mortgage-Backed Securities Risk. Mortgage-backed securities are classified generally as either commercial mortgage-backed securities or residential mortgage-backed securities, each of which is subject to certain specific risks. Mortgage-backed securities tend to be more sensitive to changes in interest rates than other types of debt securities. Investments in mortgage-backed securities are subject to both extension risk, where borrowers extend the duration of their mortgages in times of rising interest rates, and prepayment risk, where borrowers pay off their mortgages sooner than expected in times of declining interest rates. These risks may reduce the Fund’s returns. In addition, investments in mortgage-backed securities, including those comprised of subprime mortgages, may be subject to a higher degree of credit risk, valuation risk, and liquidity risk than various other types of fixed-income securities. Sovereign Debt Risk. The Fund may invest in U.S. and foreign government debt securities (“sovereign debt”). Investments in U.S. sovereign debt are considered low risk. However, investments in non-U.S. sovereign debt can involve a high degree of risk, including the risk that the governmental entity that controls the repayment of sovereign debt may not be willing or able to repay the principal and/or to pay the interest on its sovereign debt in a timely manner. A sovereign debtor’s willingness or ability to satisfy its debt obligation may be affected by various factors including, but not limited to, its cash flow situation, the extent of its foreign currency reserves, the availability of foreign exchange when a payment is due, and the relative size of its debt position in relation to its economy as a whole. In the event of default, there may be limited or no legal remedies for collecting sovereign debt and there may be no bankruptcy proceedings through which the Fund may collect all or part of the sovereign debt that a governmental entity has not repaid. High-Yield/High-Risk Bond Risk. High-yield/high-risk bonds may be more sensitive than other types of bonds to economic changes, political changes, or adverse developments specific to the company that issued the bond, which may adversely affect their value. Bank Loan Risk. Bank loans are obligations of companies or other entities entered into in connection with recapitalizations, acquisitions, and refinancings. The Fund’s investments in bank loans are generally acquired as a participation interest in, or assignment of, loans originated by a lender or other financial institution. These investments may include institutionally-traded floating and fixed-rate debt securities. Participation interests and assignments involve credit, interest rate, and liquidity risk. In addition, the bank loans underlying these securities often involve borrowers with low credit ratings whose financial conditions are troubled or uncertain, including companies that are highly leveraged or in bankruptcy proceedings. Foreign Exposure Risk. The Fund may have exposure to foreign markets as a result of its investments in foreign securities, including investments in emerging markets, which can be more volatile than the U.S. markets. As a result, its returns and net asset value may be affected to a large degree by fluctuations in currency exchange rates or political or economic conditions in a particular country. In some foreign markets, there may not be protection against failure by other parties to complete transactions. It may not be possible for the Fund to repatriate capital, dividends, interest, and other income from a particular country or governmental entity. In addition, a market swing in one or more countries or regions where the Fund has invested a significant amount of its assets may have a greater effect on the Fund’s performance than it would in a more geographically diversified portfolio. To the extent the Fund invests in foreign debt securities, such investments are sensitive to changes in interest rates. Additionally, investments in securities of foreign governments involve the risk that a foreign government may not be willing or able to pay interest or repay principal when due. The Fund’s investments in emerging market countries may involve risks greater than, or in addition to, the risks of investing in more developed countries. Portfolio Turnover Risk. Increased portfolio turnover may result in higher costs, which may have a negative effect on the Fund’s performance. In addition, higher portfolio turnover may result in the acceleration of capital gains and the recognition of greater levels of short-term capital gains, which are taxed at ordinary federal income tax rates when distributed to shareholders. Derivatives Risk. Derivatives can be highly volatile and involve risks in addition to the risks of the underlying referenced securities. Gains or losses from a derivative investment can be substantially greater than the derivative’s original cost, and can therefore involve leverage. Leverage may cause the Fund to be more volatile than if it had not used leverage. Derivatives can be less liquid than other types of investments and entail the risk that the counterparty will default on its payment obligations. Securities Lending Risk. The Fund may seek to earn additional income through lending its securities to certain qualified broker-dealers and institutions. There is the risk that when portfolio securities are lent, the securities may not be returned on a timely basis, and the Fund may experience delays and costs in recovering the security or gaining access to the collateral provided to the Fund to collateralize the loan. If the Fund is unable to recover a security on loan, the Fund may use the collateral to purchase replacement securities in the market. There is a risk that the value of the collateral could decrease below the cost of the replacement security by the time the replacement investment is made, resulting in a loss to the Fund. An investment in the Fund is not a bank deposit and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency.
Risk Lose Money [Text]	rr_RiskLoseMoney	Although the Fund may be less volatile than funds that invest most of their assets in common stocks, the Fund’s returns and yields will vary, and you could lose money.
Risk Not Insured Depository Institution [Text]	rr_RiskNotInsuredDepositoryInstitution	An investment in the Fund is not a bank deposit and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency.
Bar Chart and Performance Table [Heading]	rr_BarChartAndPerformanceTableHeading	PERFORMANCE INFORMATION
Performance Narrative [Text Block]	rr_PerformanceNarrativeTextBlock	The following information provides some indication of the risks of investing in the Fund by showing how the Fund’s performance has varied over time. Class D Shares of the Fund commenced operations on February 16, 2010, as a result of the restructuring of Class J Shares, the predecessor share class. The performance shown for Class D Shares for periods prior to February 16, 2010, reflects the performance of the Fund’s former Class J Shares, calculated using the fees and expenses in effect during the periods shown, net of any applicable fee and expense limitations or waivers. If Class D Shares of the Fund had been available during periods prior to February 16, 2010, the performance shown may have been different. The performance shown for periods following the Fund’s commencement of Class D Shares reflects the fees and expenses of Class D Shares, net of any applicable fee and expense limitations or waivers. The bar chart depicts the change in performance from year to year during the periods indicated. The table compares the Fund’s average annual returns for the periods indicated to a broad-based securities market index. The index is not actively managed and is not available for direct investment. All figures assume reinvestment of dividends and distributions. For certain periods, the Fund’s performance reflects the effect of expense waivers. Without the effect of these expense waivers, the performance shown would have been lower. The Fund’s past performance (before and after taxes) does not necessarily indicate how it will perform in the future. Updated performance information is available at janus.com/allfunds or by calling 1-800-525-3713.
Performance Information Illustrates Variability of Returns [Text]	rr_PerformanceInformationIllustratesVariabilityOfReturns	The following information provides some indication of the risks of investing in the Fund by showing how the Fund’s performance has varied over time. The bar chart depicts the change in performance from year to year during the periods indicated.
Performance Additional Market Index [Text]	rr_PerformanceAdditionalMarketIndex	The table compares the Fund’s average annual returns for the periods indicated to a broad-based securities market index. The index is not actively managed and is not available for direct investment. All figures assume reinvestment of dividends and distributions.
Performance Availability Phone [Text]	rr_PerformanceAvailabilityPhone	1-800-525-3713
Performance Availability Website Address [Text]	rr_PerformanceAvailabilityWebSiteAddress	janus.com/allfunds
Performance Past Does Not Indicate Future [Text]	rr_PerformancePastDoesNotIndicateFuture	The Fund’s past performance (before and after taxes) does not necessarily indicate how it will perform in the future.
Bar Chart [Heading]	rr_BarChartHeading	Annual Total Returns for Class D Shares (calendar year-end)
Bar Chart Closing [Text Block]	rr_BarChartClosingTextBlock	Best Quarter:  Third Quarter 2009  5.58%          Worst Quarter:  Second Quarter 2004  −2.99%
Year to Date Return, Label	rr_YearToDateReturnLabel	The Fund’s year-to-date return as of the calendar quarter ended September 30, 2013 was −0.89%.
Performance Table Heading	rr_PerformanceTableHeading	Average Annual Total Returns (periods ended 12/31/12)
Performance Table Uses Highest Federal Rate	rr_PerformanceTableUsesHighestFederalRate	After-tax returns are calculated using the historically highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes.
Performance Table Not Relevant to Tax Deferred	rr_PerformanceTableNotRelevantToTaxDeferred	Actual after-tax returns depend on your individual tax situation and may differ from those shown in the preceding table. The after-tax return information shown above does not apply to Fund shares held through a tax-deferred account, such as a 401(k) plan or an IRA.
Performance Table Narrative	rr_PerformanceTableNarrativeTextBlock	After-tax returns are calculated using distributions for the Fund’s Class D Shares for the periods following February 16, 2010; and for the Fund’s Class J Shares, the predecessor share class, for the periods prior to February 16, 2010. If Class D Shares of the Fund had been available during these earlier periods, distributions may have been different and thus, after-tax returns may have been different from those shown. After-tax returns are calculated using the historically highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes. Actual after-tax returns depend on your individual tax situation and may differ from those shown in the preceding table. The after-tax return information shown above does not apply to Fund shares held through a tax-deferred account, such as a 401(k) plan or an IRA.
Performance Table Closing [Text Block]	rr_PerformanceTableClosingTextBlock	Updated performance information is available at janus.com/allfunds or by calling 1-800-525-3713.
Janus Flexible Bond Fund | Class D Shares | Class D
Risk/Return:	rr_RiskReturnAbstract
Operating Expenses Column [Text]	rr_OperatingExpensesColumnName	Class D
Management Fees	rr_ManagementFeesOverAssets	0.40%
Other Expenses	rr_OtherExpensesOverAssets	0.20%
Total Annual Fund Operating Expenses	rr_ExpensesOverAssets	0.60%
Expense Example, By Year, Column [Text]	rr_ExpenseExampleByYearColumnName	Class D Shares
1 Year	rr_ExpenseExampleYear01	$ 61
3 Years	rr_ExpenseExampleYear03	192
5 Years	rr_ExpenseExampleYear05	335
10 Years	rr_ExpenseExampleYear10	$ 750
2003	rr_AnnualReturn2003	6.37%
2004	rr_AnnualReturn2004	3.82%
2005	rr_AnnualReturn2005	1.79%
2006	rr_AnnualReturn2006	4.12%
2007	rr_AnnualReturn2007	6.87%
2008	rr_AnnualReturn2008	5.64%
2009	rr_AnnualReturn2009	12.54%
2010	rr_AnnualReturn2010	7.53%
2011	rr_AnnualReturn2011	6.63%
2012	rr_AnnualReturn2012	8.01%
Bar Chart, Year to Date Return, Date	rr_BarChartYearToDateReturnDate	Sep. 30, 2013
Bar Chart, Year to Date Return	rr_BarChartYearToDateReturn	(0.89%)
Highest Quarterly Return, Label	rr_HighestQuarterlyReturnLabel	Best Quarter:
Highest Quarterly Return, Date	rr_BarChartHighestQuarterlyReturnDate	Sep. 30, 2009
Highest Quarterly Return	rr_BarChartHighestQuarterlyReturn	5.58%
Lowest Quarterly Return, Label	rr_LowestQuarterlyReturnLabel	Worst Quarter:
Lowest Quarterly Return, Date	rr_BarChartLowestQuarterlyReturnDate	Jun. 30, 2004
Lowest Quarterly Return	rr_BarChartLowestQuarterlyReturn	(2.99%)
Janus Flexible Bond Fund | Class D Shares | Return Before Taxes | Class D
Risk/Return:	rr_RiskReturnAbstract
Column	rr_AverageAnnualReturnColumnName	Class D Shares
Label	rr_AverageAnnualReturnLabel	Return Before Taxes
1 Year	rr_AverageAnnualReturnYear01	8.01%
5 Years	rr_AverageAnnualReturnYear05	8.05%
10 Years	rr_AverageAnnualReturnYear10	6.30%
Since Inception	rr_AverageAnnualReturnSinceInception	7.56%
Inception Date	rr_AverageAnnualReturnInceptionDate	Jul. 07, 1987
Janus Flexible Bond Fund | Class D Shares | Return After Taxes on Distributions | Class D
Risk/Return:	rr_RiskReturnAbstract
Column	rr_AverageAnnualReturnColumnName	Class D Shares
Label	rr_AverageAnnualReturnLabel	Return After Taxes on Distributions
1 Year	rr_AverageAnnualReturnYear01	6.30%
5 Years	rr_AverageAnnualReturnYear05	6.18%
10 Years	rr_AverageAnnualReturnYear10	4.54%
Since Inception	rr_AverageAnnualReturnSinceInception	4.98%
Inception Date	rr_AverageAnnualReturnInceptionDate	Jul. 07, 1987
Janus Flexible Bond Fund | Class D Shares | Return After Taxes on Distributions and Sale of Fund Shares | Class D
Risk/Return:	rr_RiskReturnAbstract
Column	rr_AverageAnnualReturnColumnName	Class D Shares
Label	rr_AverageAnnualReturnLabel	Return After Taxes on Distributions and Sale of Fund Shares
1 Year	rr_AverageAnnualReturnYear01	5.37%
5 Years	rr_AverageAnnualReturnYear05	5.86%
10 Years	rr_AverageAnnualReturnYear10	4.38%
Since Inception	rr_AverageAnnualReturnSinceInception	4.92%
Inception Date	rr_AverageAnnualReturnInceptionDate	Jul. 07, 1987
Janus Flexible Bond Fund | Class D Shares | Barclays U.S. Aggregate Bond Index (reflects no deduction for expenses, fees, or taxes)
Risk/Return:	rr_RiskReturnAbstract
Label	rr_AverageAnnualReturnLabel	Barclays U.S. Aggregate Bond Index
1 Year	rr_AverageAnnualReturnYear01	4.21%
5 Years	rr_AverageAnnualReturnYear05	5.95%
10 Years	rr_AverageAnnualReturnYear10	5.18%
Since Inception	rr_AverageAnnualReturnSinceInception	7.21%
Inception Date	rr_AverageAnnualReturnInceptionDate	Jul. 07, 1987

XML

Label	Element	Value
Risk/Return:	rr_RiskReturnAbstract
Registrant Name	dei_EntityRegistrantName	JANUS INVESTMENT FUND
Prospectus Date	rr_ProspectusDate	Oct. 28, 2013
Janus Global Allocation Fund - Moderate | Class A, C, S, I, T Shares
Risk/Return:	rr_RiskReturnAbstract
Risk/Return [Heading]	rr_RiskReturnHeading	FUND SUMMARY Janus Global Allocation Fund – Moderate (formerly named Janus Moderate Allocation Fund)
Objective [Heading]	rr_ObjectiveHeading	INVESTMENT OBJECTIVE
Objective, Primary [Text Block]	rr_ObjectivePrimaryTextBlock	Janus Global Allocation Fund – Moderate seeks total return through growth of capital and income.
Expense [Heading]	rr_ExpenseHeading	FEES AND EXPENSES OF THE FUND
Expense Narrative [Text Block]	rr_ExpenseNarrativeTextBlock	This table describes the fees and expenses that you may pay if you buy and hold Shares of the Fund. Each share class has different expenses, but represents an investment in the same Fund.
Shareholder Fees Caption [Text]	rr_ShareholderFeesCaption	SHAREHOLDER FEES (fees paid directly from your investment)
Operating Expenses Caption [Text]	rr_OperatingExpensesCaption	ANNUAL FUND OPERATING EXPENSES (expenses that you pay each year as a percentage of the value of your investment)
Portfolio Turnover [Heading]	rr_PortfolioTurnoverHeading	Portfolio Turnover:
Portfolio Turnover [Text Block]	rr_PortfolioTurnoverTextBlock	The Fund pays transaction costs, such as commissions, when it buys and sells securities (or “turns over” its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when Fund shares are held in a taxable account. These costs, which are not reflected in annual fund operating expenses or in the Example, affect the Fund’s performance. During the most recent fiscal year, the Fund’s portfolio turnover rate was 64% of the average value of its portfolio.
Portfolio Turnover, Rate	rr_PortfolioTurnoverRate	64.00%
Expense Breakpoint Discounts [Text]	rr_ExpenseBreakpointDiscounts	For Class A Shares, you may qualify for sales charge discounts if you and your family invest, or agree to invest in the future, at least $50,000 in the Fund or in other Janus mutual funds. More information about these and other discounts, as well as eligibility requirements for each share class, is available from your financial professional and in the “Purchases” section on page 52 of the Fund’s Prospectus and in the “Purchases” section on page 57 of the Fund’s Statement of Additional Information.
Expense Breakpoint, Minimum Investment Required [Amount]	rr_ExpenseBreakpointMinimumInvestmentRequiredAmount	$ 50,000
Expense Example [Heading]	rr_ExpenseExampleHeading	EXAMPLE:
Expense Example by Year [Heading]	rr_ExpenseExampleByYearHeading	The Example assumes that you invest $10,000 in the Fund for the time periods indicated and reinvest all dividends and distributions. The Example also assumes that your investment has a 5% return each year and that the Fund’s operating expenses (including the operating expenses of the underlying funds) remain the same. Although your actual costs may be higher or lower, based on these assumptions your costs would be:
Expense Example Narrative [Text Block]	rr_ExpenseExampleNarrativeTextBlock	The Example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds.
Expense Example by, Year, Caption [Text]	rr_ExpenseExampleByYearCaption	If Shares are redeemed:
Expense Example, No Redemption, By Year, Caption [Text]	rr_ExpenseExampleNoRedemptionByYearCaption	If Shares are not redeemed:
Strategy [Heading]	rr_StrategyHeading	PRINCIPAL INVESTMENT STRATEGIES
Strategy Narrative [Text Block]	rr_StrategyNarrativeTextBlock	The Fund seeks to achieve its investment objective by investing in other Janus mutual funds (“underlying funds”) that represent a variety of asset classes and investment styles and provide exposure to issuers that are economically tied to countries throughout the world. Through its investments in underlying funds, the Fund invests in issuers from several different countries and may, under unusual circumstances, be invested in a single country. As a result, the Fund normally will have approximately 40% of its net assets allocated to non-U.S. investments. The Fund may also have significant exposure to emerging markets. The Fund pursues this objective by investing in a diversified portfolio of underlying funds, resulting in an allocation of the Fund’s investments that normally provides exposure of approximately 55% to equity investments, 35% to fixed-income securities and money market instruments, and 10% to alternative investments. The target allocation and the allocation of the Fund’s assets among underlying funds are based on quantitative and qualitative analysis. Because it invests in other funds, the Fund is considered a “fund of funds.” The Fund’s asset allocation is intended to diversify investments throughout the world among equity investments, fixed-income securities, cash equivalents, and alternative investments. The portfolio manager determines the overall composition of the Fund, oversees the investment process, and is responsible for the day-to-day management of the Fund. The portfolio manager continually monitors asset class allocations and periodically rebalances the Fund’s investments in the underlying funds. The portfolio manager also regularly reviews the allocation of Fund assets in the underlying funds and may modify the underlying funds’ weightings or substitute other underlying funds to emphasize and mitigate risk exposures that may arise as a result of the implementation of the allocations. An independent asset allocation service provides evaluations of asset allocations that the portfolio manager may use in implementing the allocations among the underlying funds. Additionally, the portfolio manager consults with a committee (the “Janus Global Allocation Committee”) to regularly review the broad market, macroeconomic conditions and other global financial factors that may impact the Fund’s allocation of assets among the underlying funds and asset classes. The Janus Global Allocation Committee is comprised of investment professionals of Janus Capital and may also include investment professionals of Janus Capital’s affiliated investment advisers. The portfolio manager and Janus Global Allocation Committee normally meet on a quarterly basis. The portfolio manager may change the Fund’s asset class allocations, the underlying funds, an underlying fund’s asset category, or weightings among asset classes or underlying funds without prior shareholder notice. The Fund will normally allocate approximately 55% of its investments to underlying funds that provide varying exposure to common stocks of large U.S.-based companies, small- to mid-capitalization companies, and international companies (including those with exposure to emerging markets), approximately 35% of its investments to underlying bond funds and money market instruments, and approximately 10% of its investments to underlying funds that seek returns uncorrelated with the returns of stocks and bonds by providing exposure to alternative investments and alternative investment strategies. Refer to Appendix A in this Prospectus for a brief description of the investment strategies of each of the currently available underlying funds. When market conditions dictate a more defensive strategy, the Fund or an underlying fund may temporarily hold cash or invest its assets in temporary investments. In that case, the Fund may take positions that are inconsistent with its investment objective. As a result, the Fund may not achieve its investment objective.
Risk [Heading]	rr_RiskHeading	PRINCIPAL INVESTMENT RISKS
Risk Narrative [Text Block]	rr_RiskNarrativeTextBlock	The biggest risk is that the Fund’s returns will vary, and you could lose money. The Fund is designed for long-term investors seeking growth of capital and income. Investments in a portfolio with common stock and alternative investment exposure tend to be more volatile than many other investment choices. Main Risks Associated with the Fund Allocation Risk. The Fund’s ability to achieve its investment objective depends largely upon the portfolio manager’s allocation of assets among the underlying funds and other securities, using the optimization process (a process that utilizes quantitative analysis of a number of factors, such as historical risk, performance, fund classifications, and the relationship among underlying funds) and the judgment of the portfolio manager. You could lose money on your investment in the Fund as a result of these allocations. The Fund will typically invest in a number of different underlying funds; however, to the extent that the Fund invests a significant portion of its assets in a single underlying fund, it will be more sensitive to the risks associated with that fund and any investments in which that fund focuses. Affiliated Fund Risk. Janus Capital has the authority to select and substitute underlying affiliated mutual funds. The fees paid to Janus Capital by some Janus mutual funds are generally higher than the fees paid to Janus Capital by the Fund or by other funds and share classes available for investment by the Fund. These conditions may create a conflict of interest when selecting underlying affiliated mutual funds and share classes for investment. Janus Capital, however, is a fiduciary to the Fund and its shareholders and is legally obligated to act in their best interest when selecting underlying affiliated mutual funds. Main Risks Associated with the Underlying Funds and Securities The biggest risk is that the underlying funds’ returns will vary, and you could lose money. Market Risk. Approximately 55% of the Fund’s assets are allocated to equity investments through investments in underlying funds. The value of an underlying fund’s portfolio may decrease if the value of an individual company or security, or multiple companies or securities, in the portfolio decreases or if a portfolio manager’s belief about a company’s intrinsic worth is incorrect. Further, regardless of how well individual companies or securities perform, the value of an underlying fund’s portfolio could also decrease if there are deteriorating economic or market conditions. It is important to understand that the value of your investment may fall, sometimes sharply, in response to changes in the market, and you could lose money. Fixed-Income Securities Risk. Approximately 35% of the Fund’s assets are allocated to fixed-income securities through investments in underlying funds. Typically, the values of fixed-income securities change inversely with prevailing interest rates. Therefore, a fundamental risk of fixed-income securities is interest rate risk, which is the risk that the value of such securities will generally decline as prevailing interest rates rise, which may cause an underlying fund’s net asset value to likewise decrease. How specific fixed-income securities may react to changes in interest rates will depend on the specific characteristics of each security. Fixed-income securities are also subject to credit risk, prepayment risk, valuation risk, and liquidity risk. Credit risk is the risk that the credit strength of an issuer of a fixed-income security will weaken and/or that the issuer will be unable to make timely principal and interest payments and that the security may go into default. Prepayment risk is the risk that during periods of falling interest rates, certain fixed-income securities with higher interest rates, such as mortgage- and asset-backed securities, may be prepaid by their issuers thereby reducing the amount of interest payments. Valuation risk is the risk that one or more of the fixed-income securities in which an underlying fund invests are priced differently than the value realized upon such security’s sale. In times of market instability, valuation may be more difficult. Liquidity risk is the risk that fixed-income securities may be difficult or impossible to sell at the time that an underlying fund’s portfolio manager would like or at the price the portfolio manager believes the security is currently worth. Foreign Exposure Risk. Certain underlying funds may have significant exposure to foreign markets as a result of their investments in foreign securities, including investments in emerging markets, which can be more volatile than the U.S. markets. As a result, an underlying fund’s returns and net asset value may be affected to a large degree by fluctuations in currency exchange rates or political or economic conditions in a particular country. A market swing in one or more countries or regions where an underlying fund has invested a significant amount of its assets may have a greater effect on an underlying fund’s performance than it would in a more geographically diversified portfolio. An underlying fund’s investments in emerging market countries may involve risks greater than, or in addition to, the risks of investing in more developed countries. Emerging Markets Risk. The risks of foreign investing mentioned above are heightened when investing in emerging markets. Emerging markets securities involve a number of additional risks, which may result from less government supervision and regulation of business and industry practices (including the potential lack of strict finance and accounting controls and standards), stock exchanges, brokers, and listed companies, making these investments potentially more volatile in price and less liquid than investments in developed securities markets, resulting in greater risk to investors. In addition, an underlying fund’s investments may be denominated in foreign currencies and therefore, changes in the value of a country’s currency compared to the U.S. dollar may affect the value of an underlying fund’s investments. To the extent that an underlying fund invests a significant portion of its assets in the securities of issuers in or companies of a single country or region, it is more likely to be impacted by events or conditions affecting that country or region, which could have a negative impact on the Fund’s performance. Some of the risks of investing directly in foreign and emerging market securities may be reduced when an underlying fund invests indirectly in foreign securities through various other investment vehicles including derivatives, which also involve other risks. Sovereign Debt Risk. An underlying fund may invest in U.S. and foreign government debt securities (“sovereign debt”). Investments in U.S. sovereign debt are considered low risk. However, investments in non-U.S. sovereign debt can involve a high degree of risk, including the risk that the governmental entity that controls the repayment of sovereign debt may not be willing or able to repay the principal and/or to pay the interest on its sovereign debt in a timely manner. A sovereign debtor’s willingness or ability to satisfy its debt obligation may be affected by various factors including, but not limited to, its cash flow situation, the extent of its foreign currency reserves, the availability of foreign exchange when a payment is due, and the relative size of its debt position in relation to its economy as a whole. In the event of default, there may be limited or no legal remedies for collecting sovereign debt and there may be no bankruptcy proceedings through which the underlying fund may collect all or part of the sovereign debt that a governmental entity has not repaid. Mortgage-Backed Securities Risk. Mortgage-backed securities are classified generally as either commercial mortgage-backed securities or residential mortgage-backed securities, each of which is subject to certain specific risks. Mortgage-backed securities tend to be more sensitive to changes in interest rates than other types of debt securities. Investments in mortgage-backed securities are subject to both extension risk, where borrowers extend the duration of their mortgages in times of rising interest rates, and prepayment risk, where borrowers pay off their mortgages sooner than expected in times of declining interest rates. These risks may reduce the Fund’s returns. In addition, investments in mortgage-backed securities, including those comprised of subprime mortgages, may be subject to a higher degree of credit risk, valuation risk, and liquidity risk than various other types of fixed-income securities. Alternative Investments Allocation Risk. Approximately 10% of the Fund’s assets are allocated to alternative investments through investments in underlying funds that invest in alternative investment strategies. In connection with the Fund’s allocation to alternative investments, the Fund may invest in a Janus underlying fund, Janus Diversified Alternatives Fund, which seeks returns uncorrelated with the returns generated by investments in stocks and bonds. In addition, as part of its alternative investments allocation, the Fund may invest in Janus Global Real Estate Fund. Janus Diversified Alternatives Fund’s ability to achieve its investment objective depends largely upon the successful evaluation of the risk, potential returns, and correlation properties with respect to its investments. There is a risk that the returns provided by alternative investments may be subject to high volatility and that an underlying fund’s portfolio manager’s beliefs about the expected returns, risk and correlation properties of one or more of an underlying fund’s investments may be incorrect. There is also a risk that an underlying fund’s investments will correlate with the performance of stocks and bonds to a greater degree than anticipated. Janus Capital does not have prior experience managing the investment strategy of Janus Diversified Alternatives Fund, and there is no guarantee that the investment techniques and analysis used by the underlying fund’s portfolio managers will produce the desired results. All of these factors may negatively affect your investment in the Fund and you could lose money. Investment in the underlying funds also involves derivatives, counterparty, leverage, real estate-related, and commodity-linked investment risks. Counterparty Risk. Certain derivative and “over-the-counter” instruments, such as swaps and forwards, are subject to the risk that the other party to a contract will not fulfill its contractual obligations. Commodity-Linked Investments Risk. Certain underlying funds may invest in derivatives that have exposure to the commodities markets. Such exposure may subject an underlying fund to greater volatility than investments in traditional securities. The value of a commodity-linked derivative investment typically is based upon the price movements of a physical commodity (such as heating oil, livestock, or agricultural products), a commodity futures contract or commodity index, or some other readily measurable economic variable. The value of commodity-linked derivative instruments may therefore be affected by changes in overall market movements, volatility of the underlying benchmark, changes in interest rates, or other factors affecting a particular industry or commodity such as drought, floods, weather, livestock disease, embargoes, tariffs, and international economic, political, and regulatory developments. Derivatives Risk. Certain underlying funds may invest in derivatives. Derivatives can be highly volatile and involve risks in addition to the risks of the underlying referenced securities. Gains or losses from a derivative investment can be substantially greater than the derivative’s original cost, and can therefore involve leverage. Leverage may cause an underlying fund to be more volatile than if it had not used leverage. Derivatives can be less liquid than other types of investments and entail the risk that the counterparty will default on its payment obligations. Exchange-Traded Funds Risk. Certain underlying funds may purchase shares of exchange-traded funds (“ETFs”) to gain exposure to a particular portion of the market. ETFs are pooled investment vehicles, which may be managed or unmanaged, that generally seek to track the performance of a specific index. ETFs are traded on an exchange at market prices that may vary from the net asset value of their underlying investments. When an underlying fund invests in an ETF, in addition to directly bearing the expenses associated with its own operations, it will bear a pro rata portion of the ETF’s expenses. ETFs have certain inherent risks generally associated with investments in a portfolio of securities in which the ETF is invested, including the risk that the general level of stock prices may decline, thereby adversely affecting the value of each unit of the ETF. ETFs also involve the risk that an active trading market for an ETF’s shares may not develop or be maintained. Exchange-Traded Notes Risk. Certain underlying funds may invest in exchange-traded notes (“ETNs”), which are debt securities whose returns are linked to a particular index. ETNs are typically linked to the performance of a commodities index that reflects the potential return on unleveraged investments in futures contracts of physical commodities, plus a specified rate of interest that could be earned on cash collateral. ETNs are subject to credit risk and counterparty risk. The value of an ETN may vary and may be influenced by time to maturity, level of supply and demand for the ETN, volatility and lack of liquidity in underlying commodities markets, changes in the applicable interest rates, changes in the issuer’s credit rating, and economic, legal, political, or geographic events that affect the referenced commodity. When an underlying fund invests in ETNs it will bear its proportionate share of any fees and expenses borne by the ETN. There may be restrictions on an underlying fund’s right to redeem its investment in an ETN, which is meant to be held until maturity. An underlying fund’s decision to sell its ETN holdings may be limited by the availability of a secondary market. An investment in the Fund is not a bank deposit and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency.
Risk Lose Money [Text]	rr_RiskLoseMoney	The biggest risk is that the Fund’s returns will vary, and you could lose money.
Risk Not Insured Depository Institution [Text]	rr_RiskNotInsuredDepositoryInstitution	An investment in the Fund is not a bank deposit and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency.
Bar Chart and Performance Table [Heading]	rr_BarChartAndPerformanceTableHeading	PERFORMANCE INFORMATION
Performance Narrative [Text Block]	rr_PerformanceNarrativeTextBlock	The following information provides some indication of the risks of investing in the Fund by showing how the Fund’s performance has varied over time. Class T Shares (formerly named Class J Shares, the initial share class) of the Fund commenced operations with the Fund’s inception. Class A Shares, Class C Shares, Class S Shares, and Class I Shares of the Fund commenced operations on July 6, 2009. The performance shown for Class T Shares is calculated using the fees and expenses of Class T Shares in effect during the periods shown, net of any applicable fee and expense limitations or waivers. The performance shown for Class A Shares, Class C Shares, and Class S Shares for periods prior to July 6, 2009, reflects the performance of the Fund’s former Class J Shares, calculated using the fees and expenses of each respective share class, without the effect of any fee and expense limitations or waivers. The performance shown for Class I Shares for periods prior to July 6, 2009, reflects the performance of the Fund’s former Class J Shares, calculated using the fees and expenses of Class J Shares, net of any applicable fee and expense limitations or waivers. If Class A Shares, Class C Shares, Class S Shares, and Class I Shares of the Fund had been available during periods prior to July 6, 2009, the performance shown for each respective share class may have been different. The performance shown for periods following the Fund’s commencement of Class A Shares, Class C Shares, Class S Shares, and Class I Shares reflects the fees and expenses of each respective share class, net of any applicable fee and expense limitations or waivers. The bar chart depicts the change in performance from year to year during the periods indicated. Performance information for each underlying fund is available in its prospectus and/or the most recent annual or semiannual report. The bar chart figures do not include any applicable sales charges that an investor may pay when they buy or sell Class A Shares or Class C Shares of the Fund. If sales charges were included, the returns would be lower. The table compares the Fund’s average annual returns for the periods indicated to broad-based securities market indices. The indices are not actively managed and are not available for direct investment. All figures assume reinvestment of dividends and distributions. For certain periods, the Fund’s performance reflects the effect of expense waivers. Without the effect of these expense waivers, the performance shown would have been lower. The Fund’s past performance (before and after taxes) does not necessarily indicate how it will perform in the future. Updated performance information is available at janus.com/advisor/mutual-funds or by calling 1-877-335-2687.
Performance Information Illustrates Variability of Returns [Text]	rr_PerformanceInformationIllustratesVariabilityOfReturns	The following information provides some indication of the risks of investing in the Fund by showing how the Fund’s performance has varied over time. The bar chart depicts the change in performance from year to year during the periods indicated.
Performance Additional Market Index [Text]	rr_PerformanceAdditionalMarketIndex	The table compares the Fund’s average annual returns for the periods indicated to broad-based securities market indices. The indices are not actively managed and are not available for direct investment. All figures assume reinvestment of dividends and distributions.
Performance Availability Phone [Text]	rr_PerformanceAvailabilityPhone	1-877-335-2687
Performance Availability Website Address [Text]	rr_PerformanceAvailabilityWebSiteAddress	janus.com/advisor/mutual-funds
Performance Past Does Not Indicate Future [Text]	rr_PerformancePastDoesNotIndicateFuture	The Fund’s past performance (before and after taxes) does not necessarily indicate how it will perform in the future.
Bar Chart [Heading]	rr_BarChartHeading	Annual Total Returns for Class T Shares (calendar year-end)
Bar Chart Does Not Reflect Sales Loads [Text]	rr_BarChartDoesNotReflectSalesLoads	The bar chart figures do not include any applicable sales charges that an investor may pay when they buy or sell Class A Shares or Class C Shares of the Fund. If sales charges were included, the returns would be lower.
Bar Chart Closing [Text Block]	rr_BarChartClosingTextBlock	Best Quarter:  Second Quarter 2009  14.27%          Worst Quarter:  Fourth Quarter 2008  −11.62%
Year to Date Return, Label	rr_YearToDateReturnLabel	The Fund’s year-to-date return as of the calendar quarter ended September 30, 2013 was 9.56%.
Performance Table Heading	rr_PerformanceTableHeading	Average Annual Total Returns (periods ended 12/31/12)
Performance Table Uses Highest Federal Rate	rr_PerformanceTableUsesHighestFederalRate	After-tax returns are calculated using the historically highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes.
Performance Table Not Relevant to Tax Deferred	rr_PerformanceTableNotRelevantToTaxDeferred	Actual after-tax returns depend on your individual tax situation and may differ from those shown in the preceding table. The after-tax return information shown above does not apply to Fund shares held through a tax-deferred account, such as a 401(k) plan or an IRA.
Performance Table One Class of after Tax Shown [Text]	rr_PerformanceTableOneClassOfAfterTaxShown	After-tax returns are only shown for Class T Shares of the Fund. After-tax returns for the other classes of Shares will vary from those shown for Class T Shares due to varying sales charges (as applicable), fees, and expenses among the classes.
Performance Table Narrative	rr_PerformanceTableNarrativeTextBlock	Effective February 15, 2013, the Fund’s primary benchmark index changed from the S&P 500® Index to the Morgan Stanley Capital International (“MSCI”) All Country World IndexSM to reflect the global investment strategies of the Fund. Additionally, the Fund changed the name of its secondary benchmark index from Moderate Allocation Index to Global Moderate Allocation Index and its composition from an internally-calculated, hypothetical combination of unmanaged indices that combines total returns from the Dow Jones Wilshire 5000 Index (40%), the Barclays U.S. Aggregate Bond Index (40%), the MSCI EAFE® Index (18%), and the MSCI Emerging Markets Free IndexSM (2%) to an internally-calculated, hypothetical combination of unmanaged indices that combines total returns from the MSCI All Country World IndexSM (60%) and the Barclays Global Aggregate Bond Index (40%). The MSCI All Country World IndexSM is an unmanaged, free float-adjusted market capitalization weighted index that is designed to measure the equity market performance of global developed and emerging markets. Janus Capital believes that the foregoing benchmark index changes provide a more appropriate representation of the Fund’s revised investment strategy that includes an increased focus on global investments, including emerging markets. After-tax returns are calculated using distributions for the Fund’s Class T Shares (formerly named Class J Shares, the initial share class). After-tax returns are calculated using the historically highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes. Actual after-tax returns depend on your individual tax situation and may differ from those shown in the preceding table. The after-tax return information shown above does not apply to Fund shares held through a tax-deferred account, such as a 401(k) plan or an IRA. After-tax returns are only shown for Class T Shares of the Fund. After-tax returns for the other classes of Shares will vary from those shown for Class T Shares due to varying sales charges (as applicable), fees, and expenses among the classes.
Performance Table Closing [Text Block]	rr_PerformanceTableClosingTextBlock	Updated performance information is available at janus.com/advisor/mutual-funds or by calling 1-877-335-2687.
Janus Global Allocation Fund - Moderate | Class A, C, S, I, T Shares | Class A
Risk/Return:	rr_RiskReturnAbstract
Shareholder Fees Column [Text]	rr_ShareholderFeesColumnName	Class A
Maximum Sales Charge (load) Imposed on Purchases (as a percentage of offering price)	rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice	5.75%
Maximum Deferred Sales Charge (load) (as a percentage of the lower of original purchase price or redemption proceeds)	rr_MaximumDeferredSalesChargeOverOther	none
Operating Expenses Column [Text]	rr_OperatingExpensesColumnName	Class A
Management Fees	rr_ManagementFeesOverAssets	0.05%
Distribution/Service (12b-1) Fees	rr_DistributionAndService12b1FeesOverAssets	0.25%
Other Expenses	rr_OtherExpensesOverAssets	0.11%
Acquired Fund Fees and Expenses	rr_AcquiredFundFeesAndExpensesOverAssets	0.65%
Total Annual Fund Operating Expenses	rr_ExpensesOverAssets	1.06%
Expense Example, By Year, Column [Text]	rr_ExpenseExampleByYearColumnName	Class A Shares
1 Year	rr_ExpenseExampleYear01	677
3 Years	rr_ExpenseExampleYear03	893
5 Years	rr_ExpenseExampleYear05	1,126
10 Years	rr_ExpenseExampleYear10	1,795
Expense Example, No Redemption, By Year, Column [Text]	rr_ExpenseExampleNoRedemptionByYearColumnName	Class A Shares
1 Year	rr_ExpenseExampleNoRedemptionYear01	677
3 Years	rr_ExpenseExampleNoRedemptionYear03	893
5 Years	rr_ExpenseExampleNoRedemptionYear05	1,126
10 Years	rr_ExpenseExampleNoRedemptionYear10	1,795
Janus Global Allocation Fund - Moderate | Class A, C, S, I, T Shares | Class C
Risk/Return:	rr_RiskReturnAbstract
Shareholder Fees Column [Text]	rr_ShareholderFeesColumnName	Class C
Maximum Sales Charge (load) Imposed on Purchases (as a percentage of offering price)	rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice	none
Maximum Deferred Sales Charge (load) (as a percentage of the lower of original purchase price or redemption proceeds)	rr_MaximumDeferredSalesChargeOverOther	1.00%
Operating Expenses Column [Text]	rr_OperatingExpensesColumnName	Class C
Management Fees	rr_ManagementFeesOverAssets	0.05%
Distribution/Service (12b-1) Fees	rr_DistributionAndService12b1FeesOverAssets	1.00%
Other Expenses	rr_OtherExpensesOverAssets	0.13%
Acquired Fund Fees and Expenses	rr_AcquiredFundFeesAndExpensesOverAssets	0.65%
Total Annual Fund Operating Expenses	rr_ExpensesOverAssets	1.83%
Expense Example, By Year, Column [Text]	rr_ExpenseExampleByYearColumnName	Class C Shares
1 Year	rr_ExpenseExampleYear01	286
3 Years	rr_ExpenseExampleYear03	576
5 Years	rr_ExpenseExampleYear05	990
10 Years	rr_ExpenseExampleYear10	2,148
Expense Example, No Redemption, By Year, Column [Text]	rr_ExpenseExampleNoRedemptionByYearColumnName	Class C Shares
1 Year	rr_ExpenseExampleNoRedemptionYear01	186
3 Years	rr_ExpenseExampleNoRedemptionYear03	576
5 Years	rr_ExpenseExampleNoRedemptionYear05	990
10 Years	rr_ExpenseExampleNoRedemptionYear10	2,148
Janus Global Allocation Fund - Moderate | Class A, C, S, I, T Shares | Class S
Risk/Return:	rr_RiskReturnAbstract
Shareholder Fees Column [Text]	rr_ShareholderFeesColumnName	Class S
Maximum Sales Charge (load) Imposed on Purchases (as a percentage of offering price)	rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice	none
Maximum Deferred Sales Charge (load) (as a percentage of the lower of original purchase price or redemption proceeds)	rr_MaximumDeferredSalesChargeOverOther	none
Operating Expenses Column [Text]	rr_OperatingExpensesColumnName	Class S
Management Fees	rr_ManagementFeesOverAssets	0.05%
Distribution/Service (12b-1) Fees	rr_DistributionAndService12b1FeesOverAssets	0.25%
Other Expenses	rr_OtherExpensesOverAssets	0.30%
Acquired Fund Fees and Expenses	rr_AcquiredFundFeesAndExpensesOverAssets	0.65%
Total Annual Fund Operating Expenses	rr_ExpensesOverAssets	1.25%
Expense Example, By Year, Column [Text]	rr_ExpenseExampleByYearColumnName	Class S Shares
1 Year	rr_ExpenseExampleYear01	127
3 Years	rr_ExpenseExampleYear03	397
5 Years	rr_ExpenseExampleYear05	686
10 Years	rr_ExpenseExampleYear10	1,511
Expense Example, No Redemption, By Year, Column [Text]	rr_ExpenseExampleNoRedemptionByYearColumnName	Class S Shares
1 Year	rr_ExpenseExampleNoRedemptionYear01	127
3 Years	rr_ExpenseExampleNoRedemptionYear03	397
5 Years	rr_ExpenseExampleNoRedemptionYear05	686
10 Years	rr_ExpenseExampleNoRedemptionYear10	1,511
Janus Global Allocation Fund - Moderate | Class A, C, S, I, T Shares | Class I
Risk/Return:	rr_RiskReturnAbstract
Shareholder Fees Column [Text]	rr_ShareholderFeesColumnName	Class I
Maximum Sales Charge (load) Imposed on Purchases (as a percentage of offering price)	rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice	none
Maximum Deferred Sales Charge (load) (as a percentage of the lower of original purchase price or redemption proceeds)	rr_MaximumDeferredSalesChargeOverOther	none
Operating Expenses Column [Text]	rr_OperatingExpensesColumnName	Class I
Management Fees	rr_ManagementFeesOverAssets	0.05%
Distribution/Service (12b-1) Fees	rr_DistributionAndService12b1FeesOverAssets	none
Other Expenses	rr_OtherExpensesOverAssets	0.13%
Acquired Fund Fees and Expenses	rr_AcquiredFundFeesAndExpensesOverAssets	0.65%
Total Annual Fund Operating Expenses	rr_ExpensesOverAssets	0.83%
Expense Example, By Year, Column [Text]	rr_ExpenseExampleByYearColumnName	Class I Shares
1 Year	rr_ExpenseExampleYear01	85
3 Years	rr_ExpenseExampleYear03	265
5 Years	rr_ExpenseExampleYear05	460
10 Years	rr_ExpenseExampleYear10	1,025
Expense Example, No Redemption, By Year, Column [Text]	rr_ExpenseExampleNoRedemptionByYearColumnName	Class I Shares
1 Year	rr_ExpenseExampleNoRedemptionYear01	85
3 Years	rr_ExpenseExampleNoRedemptionYear03	265
5 Years	rr_ExpenseExampleNoRedemptionYear05	460
10 Years	rr_ExpenseExampleNoRedemptionYear10	1,025
Janus Global Allocation Fund - Moderate | Class A, C, S, I, T Shares | Class T
Risk/Return:	rr_RiskReturnAbstract
Shareholder Fees Column [Text]	rr_ShareholderFeesColumnName	Class T
Maximum Sales Charge (load) Imposed on Purchases (as a percentage of offering price)	rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice	none
Maximum Deferred Sales Charge (load) (as a percentage of the lower of original purchase price or redemption proceeds)	rr_MaximumDeferredSalesChargeOverOther	none
Operating Expenses Column [Text]	rr_OperatingExpensesColumnName	Class T
Management Fees	rr_ManagementFeesOverAssets	0.05%
Distribution/Service (12b-1) Fees	rr_DistributionAndService12b1FeesOverAssets	none
Other Expenses	rr_OtherExpensesOverAssets	0.30%
Acquired Fund Fees and Expenses	rr_AcquiredFundFeesAndExpensesOverAssets	0.65%
Total Annual Fund Operating Expenses	rr_ExpensesOverAssets	1.00%
Expense Example, By Year, Column [Text]	rr_ExpenseExampleByYearColumnName	Class T Shares
1 Year	rr_ExpenseExampleYear01	102
3 Years	rr_ExpenseExampleYear03	318
5 Years	rr_ExpenseExampleYear05	552
10 Years	rr_ExpenseExampleYear10	1,225
Expense Example, No Redemption, By Year, Column [Text]	rr_ExpenseExampleNoRedemptionByYearColumnName	Class T Shares
1 Year	rr_ExpenseExampleNoRedemptionYear01	102
3 Years	rr_ExpenseExampleNoRedemptionYear03	318
5 Years	rr_ExpenseExampleNoRedemptionYear05	552
10 Years	rr_ExpenseExampleNoRedemptionYear10	$ 1,225
2006	rr_AnnualReturn2006	14.28%
2007	rr_AnnualReturn2007	12.71%
2008	rr_AnnualReturn2008	(25.28%)
2009	rr_AnnualReturn2009	30.34%
2010	rr_AnnualReturn2010	12.19%
2011	rr_AnnualReturn2011	(2.61%)
2012	rr_AnnualReturn2012	12.59%
Bar Chart, Year to Date Return, Date	rr_BarChartYearToDateReturnDate	Sep. 30, 2013
Bar Chart, Year to Date Return	rr_BarChartYearToDateReturn	9.56%
Highest Quarterly Return, Label	rr_HighestQuarterlyReturnLabel	Best Quarter:
Highest Quarterly Return, Date	rr_BarChartHighestQuarterlyReturnDate	Jun. 30, 2009
Highest Quarterly Return	rr_BarChartHighestQuarterlyReturn	14.27%
Lowest Quarterly Return, Label	rr_LowestQuarterlyReturnLabel	Worst Quarter:
Lowest Quarterly Return, Date	rr_BarChartLowestQuarterlyReturnDate	Dec. 31, 2008
Lowest Quarterly Return	rr_BarChartLowestQuarterlyReturn	(11.62%)
Janus Global Allocation Fund - Moderate | Class A, C, S, I, T Shares | Return Before Taxes | Class A
Risk/Return:	rr_RiskReturnAbstract
Column	rr_AverageAnnualReturnColumnName	Class A Shares
Label	rr_AverageAnnualReturnLabel	Return Before Taxes	[1]
1 Year	rr_AverageAnnualReturnYear01	6.06%
5 Years	rr_AverageAnnualReturnYear05	2.35%
Since Inception	rr_AverageAnnualReturnSinceInception	5.35%
Inception Date	rr_AverageAnnualReturnInceptionDate	Dec. 30, 2005
Janus Global Allocation Fund - Moderate | Class A, C, S, I, T Shares | Return Before Taxes | Class C
Risk/Return:	rr_RiskReturnAbstract
Column	rr_AverageAnnualReturnColumnName	Class C Shares
Label	rr_AverageAnnualReturnLabel	Return Before Taxes	[2]
1 Year	rr_AverageAnnualReturnYear01	10.47%
5 Years	rr_AverageAnnualReturnYear05	2.79%
Since Inception	rr_AverageAnnualReturnSinceInception	5.45%
Inception Date	rr_AverageAnnualReturnInceptionDate	Dec. 30, 2005
Janus Global Allocation Fund - Moderate | Class A, C, S, I, T Shares | Return Before Taxes | Class S
Risk/Return:	rr_RiskReturnAbstract
Column	rr_AverageAnnualReturnColumnName	Class S Shares
Label	rr_AverageAnnualReturnLabel	Return Before Taxes
1 Year	rr_AverageAnnualReturnYear01	12.38%
5 Years	rr_AverageAnnualReturnYear05	3.33%
Since Inception	rr_AverageAnnualReturnSinceInception	5.99%
Inception Date	rr_AverageAnnualReturnInceptionDate	Dec. 30, 2005
Janus Global Allocation Fund - Moderate | Class A, C, S, I, T Shares | Return Before Taxes | Class I
Risk/Return:	rr_RiskReturnAbstract
Column	rr_AverageAnnualReturnColumnName	Class I Shares
Label	rr_AverageAnnualReturnLabel	Return Before Taxes
1 Year	rr_AverageAnnualReturnYear01	12.74%
5 Years	rr_AverageAnnualReturnYear05	3.68%
Since Inception	rr_AverageAnnualReturnSinceInception	6.39%
Inception Date	rr_AverageAnnualReturnInceptionDate	Dec. 30, 2005
Janus Global Allocation Fund - Moderate | Class A, C, S, I, T Shares | Return Before Taxes | Class T
Risk/Return:	rr_RiskReturnAbstract
Column	rr_AverageAnnualReturnColumnName	Class T Shares
Label	rr_AverageAnnualReturnLabel	Return Before Taxes
1 Year	rr_AverageAnnualReturnYear01	12.59%
5 Years	rr_AverageAnnualReturnYear05	3.68%
Since Inception	rr_AverageAnnualReturnSinceInception	6.39%
Inception Date	rr_AverageAnnualReturnInceptionDate	Dec. 30, 2005
Janus Global Allocation Fund - Moderate | Class A, C, S, I, T Shares | Return After Taxes on Distributions | Class T
Risk/Return:	rr_RiskReturnAbstract
Column	rr_AverageAnnualReturnColumnName	Class T Shares
Label	rr_AverageAnnualReturnLabel	Return After Taxes on Distributions
1 Year	rr_AverageAnnualReturnYear01	11.88%
5 Years	rr_AverageAnnualReturnYear05	2.90%
Since Inception	rr_AverageAnnualReturnSinceInception	5.57%
Inception Date	rr_AverageAnnualReturnInceptionDate	Dec. 30, 2005
Janus Global Allocation Fund - Moderate | Class A, C, S, I, T Shares | Return After Taxes on Distributions and Sale of Fund Shares | Class T
Risk/Return:	rr_RiskReturnAbstract
Column	rr_AverageAnnualReturnColumnName	Class T Shares
Label	rr_AverageAnnualReturnLabel	Return After Taxes on Distributions and Sale of Fund Shares
1 Year	rr_AverageAnnualReturnYear01	8.40%
5 Years	rr_AverageAnnualReturnYear05	2.72%
Since Inception	rr_AverageAnnualReturnSinceInception	5.11%
Inception Date	rr_AverageAnnualReturnInceptionDate	Dec. 30, 2005
Janus Global Allocation Fund - Moderate | Class A, C, S, I, T Shares | Morgan Stanley Capital International All Country World Index℠ (net of foreign withholding taxes) (reflects no deduction for expenses, fees, or taxes, except foreign withholding taxes)
Risk/Return:	rr_RiskReturnAbstract
Label	rr_AverageAnnualReturnLabel	Morgan Stanley Capital International All Country World IndexSM (net of foreign withholding taxes)
1 Year	rr_AverageAnnualReturnYear01	16.13%
5 Years	rr_AverageAnnualReturnYear05	(1.16%)
Since Inception	rr_AverageAnnualReturnSinceInception	3.52%
Inception Date	rr_AverageAnnualReturnInceptionDate	Dec. 30, 2005
Janus Global Allocation Fund - Moderate | Class A, C, S, I, T Shares | Global Moderate Allocation Index (reflects no deduction for expenses, fees, or taxes, except any applicable foreign withholding taxes)
Risk/Return:	rr_RiskReturnAbstract
Label	rr_AverageAnnualReturnLabel	Global Moderate Allocation Index
1 Year	rr_AverageAnnualReturnYear01	11.45%
5 Years	rr_AverageAnnualReturnYear05	1.89%
Since Inception	rr_AverageAnnualReturnSinceInception	4.95%
Inception Date	rr_AverageAnnualReturnInceptionDate	Dec. 30, 2005
Janus Global Allocation Fund - Moderate | Class A, C, S, I, T Shares | S&P 500® Index (reflects no deduction for expenses, fees, or taxes)
Risk/Return:	rr_RiskReturnAbstract
Label	rr_AverageAnnualReturnLabel	S&P 500® Index
1 Year	rr_AverageAnnualReturnYear01	16.00%
5 Years	rr_AverageAnnualReturnYear05	1.66%
Since Inception	rr_AverageAnnualReturnSinceInception	4.12%
Inception Date	rr_AverageAnnualReturnInceptionDate	Dec. 30, 2005
Janus Global Allocation Fund - Moderate | Class A, C, S, I, T Shares | Moderate Allocation Index (reflects no deduction for expenses, fees, or taxes, except any applicable foreign withholding taxes)
Risk/Return:	rr_RiskReturnAbstract
Label	rr_AverageAnnualReturnLabel	Moderate Allocation Index
1 Year	rr_AverageAnnualReturnYear01	11.74%
5 Years	rr_AverageAnnualReturnYear05	3.14%
Since Inception	rr_AverageAnnualReturnSinceInception	5.21%
Inception Date	rr_AverageAnnualReturnInceptionDate	Dec. 30, 2005

[1] Calculated assuming maximum permitted sales loads.

[2] The one year return is calculated to include the contingent deferred sales charge.

XML

Label	Element	Value
Risk/Return:	rr_RiskReturnAbstract
Registrant Name	dei_EntityRegistrantName	JANUS INVESTMENT FUND
Prospectus Date	rr_ProspectusDate	Oct. 28, 2013
Janus Diversified Alternatives Fund | Class D Shares
Risk/Return:	rr_RiskReturnAbstract
Risk/Return [Heading]	rr_RiskReturnHeading	FUND SUMMARY Janus Diversified Alternatives Fund
Objective [Heading]	rr_ObjectiveHeading	INVESTMENT OBJECTIVE
Objective, Primary [Text Block]	rr_ObjectivePrimaryTextBlock	Janus Diversified Alternatives Fund seeks absolute return with low correlation to stocks and bonds.
Expense [Heading]	rr_ExpenseHeading	FEES AND EXPENSES OF THE FUND
Expense Narrative [Text Block]	rr_ExpenseNarrativeTextBlock	This table describes the fees and expenses that you may pay if you buy and hold Shares of the Fund.
Operating Expenses Caption [Text]	rr_OperatingExpensesCaption	ANNUAL FUND OPERATING EXPENSES (expenses that you pay each year as a percentage of the value of your investment)
Fee Waiver or Reimbursement over Assets, Date of Termination	rr_FeeWaiverOrReimbursementOverAssetsDateOfTermination	November 1, 2014
Portfolio Turnover [Heading]	rr_PortfolioTurnoverHeading	Portfolio Turnover:
Portfolio Turnover [Text Block]	rr_PortfolioTurnoverTextBlock	The Fund pays transaction costs, such as commissions, when it buys and sells securities (or “turns over” its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when Fund shares are held in a taxable account. These costs, which are not reflected in annual fund operating expenses or in the Example, affect the Fund’s performance. During the period December 28, 2012 to June 30, 2013, the Fund’s portfolio turnover rate was 38% of the average value of its portfolio.
Portfolio Turnover, Rate	rr_PortfolioTurnoverRate	38.00%
Expense Example [Heading]	rr_ExpenseExampleHeading	EXAMPLE:
Expense Example by Year [Heading]	rr_ExpenseExampleByYearHeading	The Example assumes that you invest $10,000 in the Fund for the time periods indicated, reinvest all dividends and distributions, and then redeem all of your Shares at the end of each period. The Example also assumes that your investment has a 5% return each year and that the Fund’s operating expenses without waivers or recoupments (if applicable) remain the same. Although your actual costs may be higher or lower, based on these assumptions your costs would be:
Expense Example Narrative [Text Block]	rr_ExpenseExampleNarrativeTextBlock	The following Example is based on expenses without waivers. The Example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds.
Strategy [Heading]	rr_StrategyHeading	PRINCIPAL INVESTMENT STRATEGIES
Strategy Narrative [Text Block]	rr_StrategyNarrativeTextBlock	Under normal market conditions, the Fund pursues its investment objective by investing in a diverse group of return drivers, each a type of risk premium (collectively, “risk premia”), across equity, fixed income, commodity, and currency asset classes. Risk premia refers to the return that is expected for assuming a particular market risk. For example, investors expect a higher return in exchange for the perceived risks associated with investing in emerging markets as compared to investing in developed markets. Accordingly, a belief that emerging market equities may outperform developed market equities presents a risk premia opportunity. The Fund seeks to generate returns by identifying and isolating diverse sources of potential risk premia, and combining risk premia into a liquid portfolio that seeks to deliver consistent, absolute returns with a low correlation to the returns generated by investments in stocks and bonds. There is no guarantee that the portfolio will be successful in meeting this objective. The Fund employs a proprietary multi-factor process to allocate the Fund’s assets across the various risk premia. The process begins with an approximate equal-weighted risk to each risk premium in which the Fund invests, so that no individual risk premium contributes disproportionately to the Fund’s overall risk profile and expected returns over the long term. Next, the Fund applies additional advanced allocation methodologies to the portfolio to tactically adjust the weights of risk premia. The Fund’s portfolio managers generally rebalance risk premia allocations quarterly, but may rebalance such allocations more often from time to time to adjust the Fund’s relative risk premia exposures. The rebalancing techniques used by the Fund’s portfolio managers may result in a higher portfolio turnover rate and related expenses compared to a “buy and hold” fund strategy. The Fund may not utilize all identified risk premia in its investment process at all times. Janus Capital believes that this allocation process may provide better risk adjusted returns than a traditional asset allocation strategy that employs fixed weights for asset classes. The Fund employs various strategies within the equity, fixed income, commodity, and currency asset classes to identify risk premia and generate returns, including, but not limited to, relative value, momentum, credit, size, roll yield, systematic, and currency carry. Relative Value – Relative Value investing seeks to capture the spread between a relatively undervalued asset and a more expensive one. For example, one pool of equities often outperforms another pool of equities in a different sector or investment style. Relative value attempts to identify the difference in valuation associated with those assets and favors investments in the relatively undervalued pool to generate return. Momentum – Momentum investing seeks to capitalize on the expected continuance of trends in the market. For example, if interest rates are increasing, a momentum investor would invest in securities that would generate positive returns if rates continue to increase in the near term. Credit – Credit investing seeks to invest in fixed-income securities to realize the additional rate of return that corporate debt provides as compared to U.S. Treasuries. Size – Size investing seeks to generate returns by investing in small capitalization equity securities over large capitalization equity securities. The basis for this strategy is that over time, less liquid equities (small capitalization) will outperform more liquid equities (large capitalization). Roll Yield – Roll Yield investing seeks to capture returns from favoring certain maturities of commodity futures contracts over others. This strategy typically combines offsetting long and short exposures on various sets of individual commodity futures contracts that have different expiration dates. Systematic – Systematic investing seeks to invest in one or more asset classes, or a subset of a specific asset class, to generate the associated market return. For example, the Fund may invest a portion of the portfolio in global equities to generate the market returns associated with that type of investment. Currency Carry – Currency Carry investing seeks to generate returns by investing in higher yielding currencies versus lower yielding currencies. In a carry trade, low interest rate currencies may be sold, and high interest rate currencies may be purchased. As part of the process to identify and isolate specific risk premia and generate returns, the Fund may have both long and short exposure to securities in which it invests with respect to risk premia. The Fund’s exposure to U.S. and non-U.S. investments, which may include emerging markets, will vary based on perceived investment opportunities and the portfolio managers’ global investment outlook. The Fund will make significant use of derivative instruments, which are instruments that have a value derived from or directly linked to an underlying asset, such as equity securities, fixed-income securities, commodities, currencies, interest rates, or market indices. Derivatives will be used to gain exposure to the various asset classes in which the Fund may invest, to generate returns, for hedging purposes (to offset risks associated with an investment, currency exposure, or market conditions), to adjust currency exposure relative to a benchmark index, and to earn income and enhance returns. The Fund may utilize swaps, including equity, interest rate, currency, and total return swaps. The Fund may utilize options and futures, including forward commodity and currency contracts and U.S. Treasury, interest rate, and market index futures. The Fund’s use of options includes options purchased and sold (written). The Fund’s exposure to derivatives will vary and is not limited to those derivatives listed. The Fund’s exposure to derivatives will create a leveraging effect on the portfolio where market exposure exceeds amounts invested. This leverage will vary over time and may at times be significant. The Fund may have a substantial cash position due to margin and collateral requirements related to the Fund’s use of derivatives. Such margin and collateral requirements may limit the Fund’s ability to take advantage of other investment opportunities and may negatively affect the Fund’s ability to achieve its investment objective. The Fund’s equity and fixed-income exposure may be obtained through direct investment in equity and fixed-income securities or through investment in other mutual funds or exchange-traded funds (“ETFs”). The Fund may also utilize exchange-traded notes (“ETNs”). The equity securities in which the Fund invests may involve exposure to common stocks of companies of any size located anywhere in the world, from larger, well-established companies to smaller, emerging growth companies. The fixed-income securities in which the Fund invests may include securities of any maturity and of any credit quality, and may include exposure to government bonds, corporate bonds, convertible bonds, mortgage-backed securities, zero-coupon bonds, and high-yield/high-risk bonds, also known as “junk” bonds. The Fund’s investment in ETFs and ETNs may be used to gain exposure to market indices, a basket of securities, commodities, currencies, or a particular commodity or currency. The Fund’s exposure to the commodity markets, in whole or in part, may be made through investment in a wholly-owned subsidiary of the Fund organized under the laws of the Cayman Islands (the “Subsidiary”), which is generally subject to the same investment policies and restrictions as the Fund. The Subsidiary will invest in commodity-related derivatives such as futures and swaps, ETNs, and other investments such as cash or U.S. Treasuries which may serve as margin or collateral for the Subsidiary’s commodity-linked derivative positions.
Risk [Heading]	rr_RiskHeading	PRINCIPAL INVESTMENT RISKS
Risk Narrative [Text Block]	rr_RiskNarrativeTextBlock	The biggest risk is that the Fund’s returns will vary, and you could lose money. The Fund is designed for long-term investors seeking a portfolio which includes exposure to equity (such as stocks or any other security representing an ownership interest), fixed-income (such as bonds, notes, and debentures), commodities, and currency asset classes, and which involves the use of derivatives. Such investments, and derivatives in particular, tend to be more volatile than many other investment choices. Management Risk. The Fund’s ability to achieve its investment objective depends largely upon the portfolio managers’ successful evaluation of the risks, potential returns, and correlation properties with respect to the various risk premia in which the Fund invests. There is a risk that the returns provided by an individual risk premium may be subject to high volatility and that the portfolio managers’ beliefs about the risk, expected returns and correlation properties of various risk premia may be incorrect. Further, the Fund’s ability to achieve its investment objective also depends on the successful allocation of the Fund’s assets among various risk premia and asset classes, and you could lose money on your investment in the Fund as a result of these allocations. There is also a risk that the Fund’s investments will correlate with the performance of stocks and bonds to a greater degree than anticipated, and the Fund will not meet its investment objective. Finally, Janus Capital does not have prior experience managing a risk premia investment strategy, and there is no guarantee that the investment techniques and analysis used by the Fund’s portfolio managers will produce the desired results. Market Risk. The value of the Fund’s portfolio may decrease if the value of an individual investment, or multiple investments, in the portfolio decreases at the same time. Further, while the Fund’s goal is to produce returns that have a low correlation to the stock and bond markets, you should understand that regardless of how well the Fund’s individual investments perform, the value of the Fund’s portfolio could also decrease if there are deteriorating economic or market conditions. The value of your investment in the Fund may fall, sometimes sharply, in response to changes in the market, and you could lose money. Because the Fund seeks to produce returns that have a low correlation to the returns generated by the stock and bond markets, the Fund may underperform these markets when these markets rise sharply or experience prolonged periods of outperformance. Additionally, the Fund’s performance may be negatively affected during prolonged periods when the returns provided by the risk premia are consistently low. Derivatives Risk. Derivatives can be highly volatile and involve risks in addition to the risks of the underlying referenced securities. Gains or losses from a derivative investment can be substantially greater than the derivative’s original cost, and can therefore involve leverage. Leverage may cause the Fund to be more volatile than if it had not used leverage. Derivatives can be complex instruments and may involve analysis that differs from that required for other investment types used by the Fund. If the value of a derivative does not correlate well with the particular market or other asset class to which the derivative is intended to provide exposure, the derivative may not produce the anticipated result. Derivatives can also reduce the opportunity for gain or result in losses by offsetting positive returns in other investments. Derivatives can be less liquid than other types of investments and entail the risk that the counterparty will default on its payment obligations. If the counterparty to a derivative transaction defaults, the Fund would risk the loss of the net amount of the payments that it contractually is entitled to receive. To the extent the Fund enters into short derivative positions, the Fund may be exposed to risks similar to those associated with short sales, including the risk that the Fund’s losses are theoretically unlimited. Leverage Risk. Engaging in transactions using leverage or those having a leveraging effect subjects the Fund to certain risks. Leverage can magnify the effect of any gains or losses, causing the Fund to be more volatile than if it had not been leveraged. Certain commodity-linked derivative investments may subject the Fund to leveraged market exposure to commodities. In addition, the Fund’s assets that are used as collateral to secure short sale transactions may decrease in value while the short positions are outstanding, which may force the Fund to use its other assets to increase collateral. There is no assurance that a leveraging strategy will be successful. Short Sales Risk. Short sales are speculative transactions and involve special risks, including a greater reliance on the portfolio managers’ ability to accurately anticipate the future value of a security. The Fund will suffer a loss if it sells a security short and the value of the security rises rather than falls. The Fund’s losses are potentially unlimited in a short sale transaction. The use of short sales may also cause the Fund to have higher expenses than those of other funds. In addition, due to the investment process of long and short positions, the Fund may be subject to additional transaction costs that may lower the Fund’s returns. The Fund’s use of short sales may also have a leveraging effect on the Fund’s portfolio. Counterparty Risk. Certain derivative and “over-the-counter” instruments, such as swaps and forwards, are subject to the risk that the other party to a contract will not fulfill its contractual obligations. Commodity-Linked Investments Risk. The Fund may invest, directly or indirectly, in various commodity-linked investments that provide exposure to the commodities markets. Such exposure may subject the Fund to greater volatility than investments in traditional securities. The value of a given commodity-linked derivative investment typically is based upon the price movements of a physical commodity (such as heating oil, livestock, or agricultural products), a commodity futures contract or commodity index, or some other readily measurable economic variable. The value of commodity-linked derivative instruments may therefore be affected by changes in overall market movements, volatility of the underlying benchmark, changes in interest rates, or other factors affecting a particular industry or commodity such as drought, floods, weather, livestock disease, embargoes, tariffs, and international economic, political, and regulatory developments. Subsidiary Risk. By investing in the Subsidiary, the Fund will be indirectly exposed to the risks associated with the Subsidiary’s investments, which are generally similar to those that are permitted to be held by the Fund. The Subsidiary is not registered under the Investment Company Act of 1940, as amended (the “1940 Act”), and is not subject to all of the provisions of the 1940 Act. The Internal Revenue Service (“IRS”) has previously issued a number of private letter rulings to mutual funds (but not the Fund), in which it ruled that income from a fund’s investment in a wholly-owned foreign subsidiary that invests in commodity-linked derivatives, such as the Subsidiary, constitutes qualifying income. The IRS has suspended issuance of any further private letter rulings pending a review of its position. A change in the IRS’ position or changes in the laws of the United States and/or the Cayman Islands could result in the inability of the Fund and/or the Subsidiary to operate as described in the Fund’s Prospectus and the Statement of Additional Information. Such changes could adversely affect the Fund’s ability to meet its investment objective and jeopardize the Fund’s status as a regulated investment company under the U.S. tax code, which in turn may subject the Fund to higher tax rates and/or penalties. Foreign Exposure Risk. The Fund normally has exposure to foreign markets as a result of its investments in foreign securities, including investments in emerging markets, which can be more volatile than the U.S. markets. As a result, its returns and net asset value may be affected to a large degree by fluctuations in currency exchange rates or political or economic conditions in a particular country. In some foreign markets, there may not be protection against failure by other parties to complete transactions. It may not be possible for the Fund to repatriate capital, dividends, interest, and other income from a particular country or governmental entity. In addition, a market swing in one or more countries or regions where the Fund has invested a significant amount of its assets may have a greater effect on the Fund’s performance than it would in a more geographically diversified portfolio. To the extent the Fund invests in foreign debt securities, such investments are sensitive to changes in interest rates. Additionally, investments in securities of foreign governments involve the risk that a foreign government may not be willing or able to pay interest or repay principal when due. The Fund’s exposure to emerging market countries may involve risks greater than, or in addition to, the risks of investing in more developed countries. Eurozone Risk. A number of countries in the European Union (“EU”) have experienced severe economic and financial difficulties. As a result, financial markets in the EU have been subject to extreme volatility and declines in asset values and liquidity. Responses to these financial problems by European governments, central banks, and others, including austerity measures and reforms, may not work, may result in social unrest, and may limit future growth and economic recovery or have other unintended consequences. Further defaults or restructurings by governments and others of their debt could have additional adverse effects on economies, financial markets, and asset valuations around the world. To the extent that the Fund has exposure to European markets or to transactions tied to the value of the euro, these events could negatively affect the value and liquidity of the Fund’s investments. Emerging Markets Risk. The risks of foreign investing mentioned above are heightened when investing in emerging markets. Emerging markets securities involve a number of additional risks, which may result from less government supervision and regulation of business and industry practices (including the potential lack of strict finance and accounting controls and standards), stock exchanges, brokers, and listed companies, making these investments potentially more volatile in price and less liquid than investments in developed securities markets, resulting in greater risk to investors. There is a risk in developing countries that a future economic or political crisis could lead to price controls, forced mergers of companies, expropriation or confiscatory taxation, imposition or enforcement of foreign ownership limits, seizure, nationalization, or creation of government monopolies, any of which may have a detrimental effect on the Fund’s investments. In addition, the Fund’s investments may be denominated in foreign currencies and therefore, changes in the value of a country’s currency compared to the U.S. dollar may affect the value of the Fund’s investments. To the extent that the Fund invests a significant portion of its assets in the securities of issuers in or companies of a single country or region, it is more likely to be impacted by events or conditions affecting that country or region, which could have a negative impact on the Fund’s performance. Some of the risks of investing directly in foreign and emerging market securities may be reduced when the Fund invests indirectly in foreign securities through various other investment vehicles including derivatives, which also involve other risks. Growth Securities Risk. The Fund invests in companies after assessing their growth potential. Securities of companies perceived to be “growth” companies may be more volatile than other stocks and may involve special risks. If the portfolio managers’ perception of a company’s growth potential is not realized, the securities purchased may not perform as expected, reducing the Fund’s returns. In addition, because different types of stocks tend to shift in and out of favor depending on market and economic conditions, “growth” stocks may perform differently from the market as a whole and other types of securities. Fixed-Income Securities Risk. The Fund invests in a variety of fixed-income securities. Typically, the values of fixed-income securities change inversely with prevailing interest rates. Therefore, a fundamental risk of fixed-income securities is interest rate risk, which is the risk that the value of such securities will generally decline as prevailing interest rates rise, which may cause the Fund’s net asset value to likewise decrease. How specific fixed-income securities may react to changes in interest rates will depend on the specific characteristics of each security. Fixed-income securities are also subject to credit risk, prepayment risk, valuation risk, and liquidity risk. Credit risk is the risk that the credit strength of an issuer of a fixed-income security will weaken and/or that the issuer will be unable to make timely principal and interest payments and that the security may go into default. Prepayment risk is the risk that during periods of falling interest rates, certain fixed-income securities with higher interest rates, such as mortgage- and asset-backed securities, may be prepaid by their issuers thereby reducing the amount of interest payments. Valuation risk is the risk that one or more of the fixed-income securities in which the Fund invests are priced differently than the value realized upon such security’s sale. In times of market instability, valuation may be more difficult. Liquidity risk is the risk that fixed-income securities may be difficult or impossible to sell at the time that the portfolio managers would like or at the price the portfolio managers believe the security is currently worth. Mortgage-Backed Securities Risk. Mortgage-backed securities are classified generally as either commercial mortgage-backed securities or residential mortgage-backed securities, each of which is subject to certain specific risks. Mortgage-backed securities tend to be more sensitive to changes in interest rates than other types of debt securities. Investments in mortgage-backed securities are subject to both extension risk, where borrowers extend the duration of their mortgages in times of rising interest rates, and prepayment risk, where borrowers pay off their mortgages sooner than expected in times of declining interest rates. These risks may reduce the Fund’s returns. In addition, investments in mortgage-backed securities, including those comprised of subprime mortgages, may be subject to a higher degree of credit risk, valuation risk, and liquidity risk than various other types of fixed-income securities. Currency Risk. The Fund’s investments and strategies will involve exposure to foreign currencies. Currency risk is the risk that changes in the exchange rate between currencies will adversely affect the value (in U.S. dollar terms) of an investment. As long as the Fund holds a foreign security, its value will be affected by the value of the local currency relative to the U.S. dollar. When the Fund sells a foreign currency denominated security, its value may be worth less in U.S. dollars even if the security increases in value in its home country. U.S. dollar-denominated securities of foreign issuers may also be affected by currency risk, as the value of these securities may also be affected by changes in the issuer’s local currency. Additionally, and as a result of the Fund’s use of currency investment strategies, the Fund’s net currency positions may expose the Fund to losses independent of any securities positions. High-Yield/High-Risk Bond Risk. High-yield/high-risk bonds may be more sensitive than other types of bonds to economic changes, political changes, or adverse developments specific to the company that issued the bond, which may adversely affect their value. Portfolio Turnover Risk. Increased portfolio turnover may result in higher costs, which may have a negative effect on the Fund’s performance. In addition, higher portfolio turnover may result in the acceleration of capital gains and the recognition of greater levels of short-term capital gains, which are taxed at ordinary federal income tax rates when distributed to shareholders. Exchange-Traded Funds Risk. The Fund may invest in ETFs, which are typically open-end investment companies that are traded on a national securities exchange. ETFs typically incur fees, such as investment advisory fees and other operating expenses that are separate from those of the Fund, which will be indirectly paid by the Fund. As a result, the cost of investing in the Fund may be higher than the cost of investing directly in ETFs and may be higher than other mutual funds that invest directly in stocks and bonds. Further, the price movement of an ETF may fluctuate against the underlying securities or commodities it tracks and may result in a loss. Because the value of ETF shares depends on the demand in the market, the Fund may not be able to purchase or sell an ETF at the most optimal time, which could adversely affect the Fund’s performance. The ETFs in which the Fund invests are subject to specific risks, depending on the investment strategy of the ETF. In turn, the Fund will be subject to substantially the same risks as those associated with direct exposure to the securities or commodities held by the ETF. Because the Fund may invest in a broad range of ETFs, such risks may include, but are not limited to, leverage risk, foreign exposure risk, fixed-income risk, and commodity-linked investments risk. Exchange-Traded Notes Risk. The Fund may invest in ETNs, which are debt securities whose returns are linked to a particular index. ETNs are typically linked to the performance of a commodities index that reflects the potential return on unleveraged investments in futures contracts of physical commodities, plus a specified rate of interest that could be earned on cash collateral. ETNs are subject to credit risk and counterparty risk. The value of an ETN may vary and may be influenced by time to maturity, level of supply and demand for the ETN, volatility and lack of liquidity in underlying commodities markets, changes in the applicable interest rates, changes in the issuer’s credit rating, and economic, legal, political, or geographic events that affect the referenced commodity. When the Fund invests in ETNs it will bear its proportionate share of any fees and expenses borne by the ETN. There may be restrictions on the Fund’s right to redeem its investment in an ETN, which is meant to be held until maturity. The Fund’s decision to sell its ETN holdings may be limited by the availability of a secondary market. Nondiversification Risk. Although the Fund seeks diverse sources of potential return or risk premia, the Fund is classified as nondiversified under the 1940 Act. This gives the Fund’s portfolio managers more flexibility to hold larger positions in a smaller number of securities. As a result, an increase or decrease in the value of a single security held by the Fund may have a greater impact on the Fund’s net asset value and total return. An investment in the Fund is not a bank deposit and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency.
Risk Lose Money [Text]	rr_RiskLoseMoney	The biggest risk is that the Fund’s returns will vary, and you could lose money.
Risk Nondiversified Status [Text]	rr_RiskNondiversifiedStatus	Nondiversification Risk. Although the Fund seeks diverse sources of potential return or risk premia, the Fund is classified as nondiversified under the 1940 Act. This gives the Fund's portfolio managers more flexibility to hold larger positions in a smaller number of securities. As a result, an increase or decrease in the value of a single security held by the Fund may have a greater impact on the Fund's net asset value and total return.
Risk Not Insured Depository Institution [Text]	rr_RiskNotInsuredDepositoryInstitution	An investment in the Fund is not a bank deposit and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency.
Bar Chart and Performance Table [Heading]	rr_BarChartAndPerformanceTableHeading	PERFORMANCE INFORMATION
Performance Narrative [Text Block]	rr_PerformanceNarrativeTextBlock	The Fund does not have a full calendar year of operations. Performance information for certain periods is included in the Fund’s first annual and/or semiannual report.
Performance One Year or Less [Text]	rr_PerformanceOneYearOrLess	The Fund does not have a full calendar year of operations.
Janus Diversified Alternatives Fund | Class D Shares | Class D
Risk/Return:	rr_RiskReturnAbstract
Operating Expenses Column [Text]	rr_OperatingExpensesColumnName	Class D
Management Fees of the Fund and the Subsidiary	rr_ManagementFeesOverAssets	1.00%	[1]
Other Expenses of the Fund	rr_Component1OtherExpensesOverAssets	1.15%	[2]
Other Expenses of the Subsidiary	rr_Component2OtherExpensesOverAssets	0.02%
Other Expenses	rr_OtherExpensesOverAssets	1.17%
Total Annual Fund Operating Expenses	rr_ExpensesOverAssets	2.17%	[3]
Fee Waiver	rr_FeeWaiverOrReimbursementOverAssets	0.78%	[3]
Total Annual Fund Operating Expenses After Fee Waiver	rr_NetExpensesOverAssets	1.39%	[3]
Expense Example, By Year, Column [Text]	rr_ExpenseExampleByYearColumnName	Class D Shares
1 Year	rr_ExpenseExampleYear01	$ 220
3 Years	rr_ExpenseExampleYear03	679
5 Years	rr_ExpenseExampleYear05	1,164
10 Years	rr_ExpenseExampleYear10	$ 2,503

[1] The Fund may invest in commodity-linked investments through a wholly-owned subsidiary of the Fund that invests in commodity-linked investments. Janus Capital has contractually agreed that to the extent the Fund invests in the subsidiary, it shall not collect advisory fees from the Fund in an amount equal to the fee it collects from the subsidiary. The management fee waiver arrangement may not be discontinued by Janus Capital as long as its contract with the subsidiary is in place.

[2] Other Expenses are based on the estimated expenses that the Fund expects to incur.

[3] Janus Capital has contractually agreed to waive its investment advisory fee and/or reimburse Fund expenses to the extent that the Fund's total annual fund operating expenses, which include the other expenses of the subsidiary shown above (excluding administrative services fees payable pursuant to the Transfer Agency Agreement, brokerage commissions, interest, dividends, taxes, acquired fund fees and expenses, and extraordinary expenses) exceed 1.25% until at least November 1, 2014. The contractual waiver may be terminated or modified prior to this date only at the discretion of the Board of Trustees. For a period of three years subsequent to the Fund's commencement of operations (December 28, 2012) or until the Fund's assets exceed the first breakpoint in the investment advisory fee schedule, whichever occurs first, Janus Capital may recover from the Fund fees and expenses previously waived or reimbursed, which could then be considered a deferral, if the Fund's expense ratio, including recovered expenses, falls below the expense limit.

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Janus Global Allocation Fund - Moderate | Class A, C, S, I, T Shares

FUND SUMMARY

Janus Global Allocation Fund – Moderate
(formerly named Janus Moderate Allocation Fund)

INVESTMENT OBJECTIVE

Janus Global Allocation Fund – Moderate seeks total return through growth of capital and income.

FEES AND EXPENSES OF THE FUND

This table describes the fees and expenses that you may pay if you buy and hold Shares of the Fund. Each share class has different expenses, but represents an investment in the same Fund.

For Class A Shares, you may qualify for sales charge discounts if you and your family invest, or agree to invest in the future, at least $50,000 in the Fund or in other Janus mutual funds. More information about these and other discounts, as well as eligibility requirements for each share class, is available from your financial professional and in the “Purchases” section on page 52 of the Fund’s Prospectus and in the “Purchases” section on page 57 of the Fund’s Statement of Additional Information.

SHAREHOLDER FEES
(fees paid directly from your investment)

Shareholder Fees Janus Global Allocation Fund - Moderate Class A, C, S, I, T Shares	Class A	Class C	Class S	Class I	Class T
Shareholder Fees Column [Text]	Class A	Class C	Class S	Class I	Class T
Maximum Sales Charge (load) Imposed on Purchases (as a percentage of offering price)	5.75%	none	none	none	none
Maximum Deferred Sales Charge (load) (as a percentage of the lower of original purchase price or redemption proceeds)	none	1.00%	none	none	none

ANNUAL FUND OPERATING EXPENSES
(expenses that you pay each year as a percentage of the value of your investment)

Annual Fund Operating Expenses Janus Global Allocation Fund - Moderate Class A, C, S, I, T Shares	Class A	Class C	Class S	Class I	Class T
Operating Expenses Column [Text]	Class A	Class C	Class S	Class I	Class T
Management Fees	0.05%	0.05%	0.05%	0.05%	0.05%
Distribution/Service (12b-1) Fees	0.25%	1.00%	0.25%	none	none
Other Expenses	0.11%	0.13%	0.30%	0.13%	0.30%
Acquired Fund Fees and Expenses	0.65%	0.65%	0.65%	0.65%	0.65%
Total Annual Fund Operating Expenses	1.06%	1.83%	1.25%	0.83%	1.00%

EXAMPLE:

The Example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds.

The Example assumes that you invest $10,000 in the Fund for the time periods indicated and reinvest all dividends and distributions. The Example also assumes that your investment has a 5% return each year and that the Fund’s operating expenses (including the operating expenses of the underlying funds) remain the same. Although your actual costs may be higher or lower, based on these assumptions your costs would be:

If Shares are redeemed:

Expense Example Janus Global Allocation Fund - Moderate Class A, C, S, I, T Shares (USD $)	Expense Example, By Year, Column [Text]	1 Year	3 Years	5 Years	10 Years
Class A	Class A Shares	677	893	1,126	1,795
Class C	Class C Shares	286	576	990	2,148
Class S	Class S Shares	127	397	686	1,511
Class I	Class I Shares	85	265	460	1,025
Class T	Class T Shares	102	318	552	1,225

If Shares are not redeemed:

Expense Example, No Redemption Janus Global Allocation Fund - Moderate Class A, C, S, I, T Shares (USD $)	Expense Example, No Redemption, By Year, Column [Text]	1 Year	3 Years	5 Years	10 Years
Class A	Class A Shares	677	893	1,126	1,795
Class C	Class C Shares	186	576	990	2,148
Class S	Class S Shares	127	397	686	1,511
Class I	Class I Shares	85	265	460	1,025
Class T	Class T Shares	102	318	552	1,225

Portfolio Turnover: 

The Fund pays transaction costs, such as commissions, when it buys and sells securities (or “turns over” its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when Fund shares are held in a taxable account. These costs, which are not reflected in annual fund operating expenses or in the Example, affect the Fund’s performance. During the most recent fiscal year, the Fund’s portfolio turnover rate was 64% of the average value of its portfolio.

PRINCIPAL INVESTMENT STRATEGIES

The Fund seeks to achieve its investment objective by investing in other Janus mutual funds (“underlying funds”) that represent a variety of asset classes and investment styles and provide exposure to issuers that are economically tied to countries throughout the world. Through its investments in underlying funds, the Fund invests in issuers from several different countries and may, under unusual circumstances, be invested in a single country. As a result, the Fund normally will have approximately 40% of its net assets allocated to non-U.S. investments. The Fund may also have significant exposure to emerging markets.

The Fund pursues this objective by investing in a diversified portfolio of underlying funds, resulting in an allocation of the Fund’s investments that normally provides exposure of approximately 55% to equity investments, 35% to fixed-income securities and money market instruments, and 10% to alternative investments. The target allocation and the allocation of the Fund’s assets among underlying funds are based on quantitative and qualitative analysis. Because it invests in other funds, the Fund is considered a “fund of funds.”

The Fund’s asset allocation is intended to diversify investments throughout the world among equity investments, fixed-income securities, cash equivalents, and alternative investments. The portfolio manager determines the overall composition of the Fund, oversees the investment process, and is responsible for the day-to-day management of the Fund. The portfolio manager continually monitors asset class allocations and periodically rebalances the Fund’s investments in the underlying funds. The portfolio manager also regularly reviews the allocation of Fund assets in the underlying funds and may modify the underlying funds’ weightings or substitute other underlying funds to emphasize and mitigate risk exposures that may arise as a result of the implementation of the allocations. An independent asset allocation service provides evaluations of asset allocations that the portfolio manager may use in implementing the allocations among the underlying funds.

Additionally, the portfolio manager consults with a committee (the “Janus Global Allocation Committee”) to regularly review the broad market, macroeconomic conditions and other global financial factors that may impact the Fund’s allocation of assets among the underlying funds and asset classes. The Janus Global Allocation Committee is comprised of investment professionals of Janus Capital and may also include investment professionals of Janus Capital’s affiliated investment advisers. The portfolio manager and Janus Global Allocation Committee normally meet on a quarterly basis. The portfolio manager may change the Fund’s asset class allocations, the underlying funds, an underlying fund’s asset category, or weightings among asset classes or underlying funds without prior shareholder notice.

The Fund will normally allocate approximately 55% of its investments to underlying funds that provide varying exposure to common stocks of large U.S.-based companies, small- to mid-capitalization companies, and international companies (including those with exposure to emerging markets), approximately 35% of its investments to underlying bond funds and money market instruments, and approximately 10% of its investments to underlying funds that seek returns uncorrelated with the returns of stocks and bonds by providing exposure to alternative investments and alternative investment strategies. Refer to Appendix A in this Prospectus for a brief description of the investment strategies of each of the currently available underlying funds.

When market conditions dictate a more defensive strategy, the Fund or an underlying fund may temporarily hold cash or invest its assets in temporary investments. In that case, the Fund may take positions that are inconsistent with its investment objective. As a result, the Fund may not achieve its investment objective.

PRINCIPAL INVESTMENT RISKS

The biggest risk is that the Fund’s returns will vary, and you could lose money. The Fund is designed for long-term investors seeking growth of capital and income. Investments in a portfolio with common stock and alternative investment exposure tend to be more volatile than many other investment choices.

Main Risks Associated with the Fund
Allocation Risk. The Fund’s ability to achieve its investment objective depends largely upon the portfolio manager’s allocation of assets among the underlying funds and other securities, using the optimization process (a process that utilizes quantitative analysis of a number of factors, such as historical risk, performance, fund classifications, and the relationship among underlying funds) and the judgment of the portfolio manager. You could lose money on your investment in the Fund as a result of these allocations. The Fund will typically invest in a number of different underlying funds; however, to the extent that the Fund invests a significant portion of its assets in a single underlying fund, it will be more sensitive to the risks associated with that fund and any investments in which that fund focuses.

Affiliated Fund Risk. Janus Capital has the authority to select and substitute underlying affiliated mutual funds. The fees paid to Janus Capital by some Janus mutual funds are generally higher than the fees paid to Janus Capital by the Fund or by other funds and share classes available for investment by the Fund. These conditions may create a conflict of interest when selecting underlying affiliated mutual funds and share classes for investment. Janus Capital, however, is a fiduciary to the Fund and its shareholders and is legally obligated to act in their best interest when selecting underlying affiliated mutual funds.

Main Risks Associated with the Underlying Funds and Securities
The biggest risk is that the underlying funds’ returns will vary, and you could lose money.

Market Risk. Approximately 55% of the Fund’s assets are allocated to equity investments through investments in underlying funds. The value of an underlying fund’s portfolio may decrease if the value of an individual company or security, or multiple companies or securities, in the portfolio decreases or if a portfolio manager’s belief about a company’s intrinsic worth is incorrect. Further, regardless of how well individual companies or securities perform, the value of an underlying fund’s portfolio could also decrease if there are deteriorating economic or market conditions. It is important to understand that the value of your investment may fall, sometimes sharply, in response to changes in the market, and you could lose money.

Fixed-Income Securities Risk. Approximately 35% of the Fund’s assets are allocated to fixed-income securities through investments in underlying funds. Typically, the values of fixed-income securities change inversely with prevailing interest rates. Therefore, a fundamental risk of fixed-income securities is interest rate risk, which is the risk that the value of such securities will generally decline as prevailing interest rates rise, which may cause an underlying fund’s net asset value to likewise decrease. How specific fixed-income securities may react to changes in interest rates will depend on the specific characteristics of each security. Fixed-income securities are also subject to credit risk, prepayment risk, valuation risk, and liquidity risk. Credit risk is the risk that the credit strength of an issuer of a fixed-income security will weaken and/or that the issuer will be unable to make timely principal and interest payments and that the security may go into default. Prepayment risk is the risk that during periods of falling interest rates, certain fixed-income securities with higher interest rates, such as mortgage- and asset-backed securities, may be prepaid by their issuers thereby reducing the amount of interest payments. Valuation risk is the risk that one or more of the fixed-income securities in which an underlying fund invests are priced differently than the value realized upon such security’s sale. In times of market instability, valuation may be more difficult. Liquidity risk is the risk that fixed-income securities may be difficult or impossible to sell at the time that an underlying fund’s portfolio manager would like or at the price the portfolio manager believes the security is currently worth.

Foreign Exposure Risk. Certain underlying funds may have significant exposure to foreign markets as a result of their investments in foreign securities, including investments in emerging markets, which can be more volatile than the U.S. markets. As a result, an underlying fund’s returns and net asset value may be affected to a large degree by fluctuations in currency exchange rates or political or economic conditions in a particular country. A market swing in one or more countries or regions where an underlying fund has invested a significant amount of its assets may have a greater effect on an underlying fund’s performance than it would in a more geographically diversified portfolio. An underlying fund’s investments in emerging market countries may involve risks greater than, or in addition to, the risks of investing in more developed countries.

Emerging Markets Risk. The risks of foreign investing mentioned above are heightened when investing in emerging markets. Emerging markets securities involve a number of additional risks, which may result from less government supervision and regulation of business and industry practices (including the potential lack of strict finance and accounting controls and standards), stock exchanges, brokers, and listed companies, making these investments potentially more volatile in price and less liquid than investments in developed securities markets, resulting in greater risk to investors. In addition, an underlying fund’s investments may be denominated in foreign currencies and therefore, changes in the value of a country’s currency compared to the U.S. dollar may affect the value of an underlying fund’s investments. To the extent that an underlying fund invests a significant portion of its assets in the securities of issuers in or companies of a single country or region, it is more likely to be impacted by events or conditions affecting that country or region, which could have a negative impact on the Fund’s performance. Some of the risks of investing directly in foreign and emerging market securities may be reduced when an underlying fund invests indirectly in foreign securities through various other investment vehicles including derivatives, which also involve other risks.

Sovereign Debt Risk. An underlying fund may invest in U.S. and foreign government debt securities (“sovereign debt”). Investments in U.S. sovereign debt are considered low risk. However, investments in non-U.S. sovereign debt can involve a high degree of risk, including the risk that the governmental entity that controls the repayment of sovereign debt may not be willing or able to repay the principal and/or to pay the interest on its sovereign debt in a timely manner. A sovereign debtor’s willingness or ability to satisfy its debt obligation may be affected by various factors including, but not limited to, its cash flow situation, the extent of its foreign currency reserves, the availability of foreign exchange when a payment is due, and the relative size of its debt position in relation to its economy as a whole. In the event of default, there may be limited or no legal remedies for collecting sovereign debt and there may be no bankruptcy proceedings through which the underlying fund may collect all or part of the sovereign debt that a governmental entity has not repaid.

Mortgage-Backed Securities Risk. Mortgage-backed securities are classified generally as either commercial mortgage-backed securities or residential mortgage-backed securities, each of which is subject to certain specific risks. Mortgage-backed securities tend to be more sensitive to changes in interest rates than other types of debt securities. Investments in mortgage-backed securities are subject to both extension risk, where borrowers extend the duration of their mortgages in times of rising interest rates, and prepayment risk, where borrowers pay off their mortgages sooner than expected in times of declining interest rates. These risks may reduce the Fund’s returns. In addition, investments in mortgage-backed securities, including those comprised of subprime mortgages, may be subject to a higher degree of credit risk, valuation risk, and liquidity risk than various other types of fixed-income securities.

Alternative Investments Allocation Risk. Approximately 10% of the Fund’s assets are allocated to alternative investments through investments in underlying funds that invest in alternative investment strategies. In connection with the Fund’s allocation to alternative investments, the Fund may invest in a Janus underlying fund, Janus Diversified Alternatives Fund, which seeks returns uncorrelated with the returns generated by investments in stocks and bonds. In addition, as part of its alternative investments allocation, the Fund may invest in Janus Global Real Estate Fund. Janus Diversified Alternatives Fund’s ability to achieve its investment objective depends largely upon the successful evaluation of the risk, potential returns, and correlation properties with respect to its investments. There is a risk that the returns provided by alternative investments may be subject to high volatility and that an underlying fund’s portfolio manager’s beliefs about the expected returns, risk and correlation properties of one or more of an underlying fund’s investments may be incorrect. There is also a risk that an underlying fund’s investments will correlate with the performance of stocks and bonds to a greater degree than anticipated. Janus Capital does not have prior experience managing the investment strategy of Janus Diversified Alternatives Fund, and there is no guarantee that the investment techniques and analysis used by the underlying fund’s portfolio managers will produce the desired results. All of these factors may negatively affect your investment in the Fund and you could lose money. Investment in the underlying funds also involves derivatives, counterparty, leverage, real estate-related, and commodity-linked investment risks.

Counterparty Risk. Certain derivative and “over-the-counter” instruments, such as swaps and forwards, are subject to the risk that the other party to a contract will not fulfill its contractual obligations.

Commodity-Linked Investments Risk. Certain underlying funds may invest in derivatives that have exposure to the commodities markets. Such exposure may subject an underlying fund to greater volatility than investments in traditional securities. The value of a commodity-linked derivative investment typically is based upon the price movements of a physical commodity (such as heating oil, livestock, or agricultural products), a commodity futures contract or commodity index, or some other readily measurable economic variable. The value of commodity-linked derivative instruments may therefore be affected by changes in overall market movements, volatility of the underlying benchmark, changes in interest rates, or other factors affecting a particular industry or commodity such as drought, floods, weather, livestock disease, embargoes, tariffs, and international economic, political, and regulatory developments.

Derivatives Risk. Certain underlying funds may invest in derivatives. Derivatives can be highly volatile and involve risks in addition to the risks of the underlying referenced securities. Gains or losses from a derivative investment can be substantially greater than the derivative’s original cost, and can therefore involve leverage. Leverage may cause an underlying fund to be more volatile than if it had not used leverage. Derivatives can be less liquid than other types of investments and entail the risk that the counterparty will default on its payment obligations.

Exchange-Traded Funds Risk. Certain underlying funds may purchase shares of exchange-traded funds (“ETFs”) to gain exposure to a particular portion of the market. ETFs are pooled investment vehicles, which may be managed or unmanaged, that generally seek to track the performance of a specific index. ETFs are traded on an exchange at market prices that may vary from the net asset value of their underlying investments. When an underlying fund invests in an ETF, in addition to directly bearing the expenses associated with its own operations, it will bear a pro rata portion of the ETF’s expenses. ETFs have certain inherent risks generally associated with investments in a portfolio of securities in which the ETF is invested, including the risk that the general level of stock prices may decline, thereby adversely affecting the value of each unit of the ETF. ETFs also involve the risk that an active trading market for an ETF’s shares may not develop or be maintained.

Exchange-Traded Notes Risk. Certain underlying funds may invest in exchange-traded notes (“ETNs”), which are debt securities whose returns are linked to a particular index. ETNs are typically linked to the performance of a commodities index that reflects the potential return on unleveraged investments in futures contracts of physical commodities, plus a specified rate of interest that could be earned on cash collateral. ETNs are subject to credit risk and counterparty risk. The value of an ETN may vary and may be influenced by time to maturity, level of supply and demand for the ETN, volatility and lack of liquidity in underlying commodities markets, changes in the applicable interest rates, changes in the issuer’s credit rating, and economic, legal, political, or geographic events that affect the referenced commodity. When an underlying fund invests in ETNs it will bear its proportionate share of any fees and expenses borne by the ETN. There may be restrictions on an underlying fund’s right to redeem its investment in an ETN, which is meant to be held until maturity. An underlying fund’s decision to sell its ETN holdings may be limited by the availability of a secondary market.

An investment in the Fund is not a bank deposit and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency.

PERFORMANCE INFORMATION

The following information provides some indication of the risks of investing in the Fund by showing how the Fund’s performance has varied over time. Class T Shares (formerly named Class J Shares, the initial share class) of the Fund commenced operations with the Fund’s inception. Class A Shares, Class C Shares, Class S Shares, and Class I Shares of the Fund commenced operations on July 6, 2009.

• The performance shown for Class T Shares is calculated using the fees and expenses of Class T Shares in effect during the periods shown, net of any applicable fee and expense limitations or waivers.
• The performance shown for Class A Shares, Class C Shares, and Class S Shares for periods prior to July 6, 2009, reflects the performance of the Fund’s former Class J Shares, calculated using the fees and expenses of each respective share class, without the effect of any fee and expense limitations or waivers.
• The performance shown for Class I Shares for periods prior to July 6, 2009, reflects the performance of the Fund’s former Class J Shares, calculated using the fees and expenses of Class J Shares, net of any applicable fee and expense limitations or waivers.

If Class A Shares, Class C Shares, Class S Shares, and Class I Shares of the Fund had been available during periods prior to July 6, 2009, the performance shown for each respective share class may have been different. The performance shown for periods following the Fund’s commencement of Class A Shares, Class C Shares, Class S Shares, and Class I Shares reflects the fees and expenses of each respective share class, net of any applicable fee and expense limitations or waivers.

The bar chart depicts the change in performance from year to year during the periods indicated. Performance information for each underlying fund is available in its prospectus and/or the most recent annual or semiannual report. The bar chart figures do not include any applicable sales charges that an investor may pay when they buy or sell Class A Shares or Class C Shares of the Fund. If sales charges were included, the returns would be lower. The table compares the Fund’s average annual returns for the periods indicated to broad-based securities market indices. The indices are not actively managed and are not available for direct investment. All figures assume reinvestment of dividends and distributions. For certain periods, the Fund’s performance reflects the effect of expense waivers. Without the effect of these expense waivers, the performance shown would have been lower.

The Fund’s past performance (before and after taxes) does not necessarily indicate how it will perform in the future. Updated performance information is available at janus.com/advisor/mutual-funds or by calling 1-877-335-2687.

Annual Total Returns for Class T Shares (calendar year-end)

Best Quarter:  Second Quarter 2009  14.27%          Worst Quarter:  Fourth Quarter 2008  −11.62%

The Fund’s year-to-date return as of the calendar quarter ended September 30, 2013 was 9.56%.

Average Annual Total Returns (periods ended 12/31/12)

Average Annual Total Returns Janus Global Allocation Fund - Moderate Class A, C, S, I, T Shares	Column	Label		1 Year	5 Years	Since Inception	Inception Date
Class T Return Before Taxes	Class T Shares	Return Before Taxes		12.59%	3.68%	6.39%	Dec. 30, 2005
Class T Return After Taxes on Distributions	Class T Shares	Return After Taxes on Distributions		11.88%	2.90%	5.57%	Dec. 30, 2005
Class T Return After Taxes on Distributions and Sale of Fund Shares	Class T Shares	Return After Taxes on Distributions and Sale of Fund Shares		8.40%	2.72%	5.11%	Dec. 30, 2005
Class A Return Before Taxes	Class A Shares	Return Before Taxes	[1]	6.06%	2.35%	5.35%	Dec. 30, 2005
Class C Return Before Taxes	Class C Shares	Return Before Taxes	[2]	10.47%	2.79%	5.45%	Dec. 30, 2005
Class S Return Before Taxes	Class S Shares	Return Before Taxes		12.38%	3.33%	5.99%	Dec. 30, 2005
Class I Return Before Taxes	Class I Shares	Return Before Taxes		12.74%	3.68%	6.39%	Dec. 30, 2005
Morgan Stanley Capital International All Country World Index℠ (net of foreign withholding taxes) (reflects no deduction for expenses, fees, or taxes, except foreign withholding taxes)		Morgan Stanley Capital International All Country World IndexSM (net of foreign withholding taxes)		16.13%	(1.16%)	3.52%	Dec. 30, 2005
Global Moderate Allocation Index (reflects no deduction for expenses, fees, or taxes, except any applicable foreign withholding taxes)		Global Moderate Allocation Index		11.45%	1.89%	4.95%	Dec. 30, 2005
S&P 500® Index (reflects no deduction for expenses, fees, or taxes)		S&P 500® Index		16.00%	1.66%	4.12%	Dec. 30, 2005
Moderate Allocation Index (reflects no deduction for expenses, fees, or taxes, except any applicable foreign withholding taxes)		Moderate Allocation Index		11.74%	3.14%	5.21%	Dec. 30, 2005

Effective February 15, 2013, the Fund’s primary benchmark index changed from the S&P 500^® Index to the Morgan Stanley Capital International (“MSCI”) All Country World Index^SM to reflect the global investment strategies of the Fund. Additionally, the Fund changed the name of its secondary benchmark index from Moderate Allocation Index to Global Moderate Allocation Index and its composition from an internally-calculated, hypothetical combination of unmanaged indices that combines total returns from the Dow Jones Wilshire 5000 Index (40%), the Barclays U.S. Aggregate Bond Index (40%), the MSCI EAFE^® Index (18%), and the MSCI Emerging Markets Free Index^SM (2%) to an internally-calculated, hypothetical combination of unmanaged indices that combines total returns from the MSCI All Country World Index^SM (60%) and the Barclays Global Aggregate Bond Index (40%). The MSCI All Country World Index^SM is an unmanaged, free float-adjusted market capitalization weighted index that is designed to measure the equity market performance of global developed and emerging markets. Janus Capital believes that the foregoing benchmark index changes provide a more appropriate representation of the Fund’s revised investment strategy that includes an increased focus on global investments, including emerging markets.

After-tax returns are calculated using distributions for the Fund’s Class T Shares (formerly named Class J Shares, the initial share class). After-tax returns are calculated using the historically highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes. Actual after-tax returns depend on your individual tax situation and may differ from those shown in the preceding table. The after-tax return information shown above does not apply to Fund shares held through a tax-deferred account, such as a 401(k) plan or an IRA.

After-tax returns are only shown for Class T Shares of the Fund. After-tax returns for the other classes of Shares will vary from those shown for Class T Shares due to varying sales charges (as applicable), fees, and expenses among the classes.

[1] Calculated assuming maximum permitted sales loads.

[2] The one year return is calculated to include the contingent deferred sales charge.

XML

Label	Element	Value
Risk/Return:	rr_RiskReturnAbstract
Registrant Name	dei_EntityRegistrantName	JANUS INVESTMENT FUND
Prospectus Date	rr_ProspectusDate	Oct. 28, 2013
INTECH U.S. Core Fund | Class D Shares
Risk/Return:	rr_RiskReturnAbstract
Risk/Return [Heading]	rr_RiskReturnHeading	FUND SUMMARY INTECH U.S. Core Fund
Objective [Heading]	rr_ObjectiveHeading	INVESTMENT OBJECTIVE
Objective, Primary [Text Block]	rr_ObjectivePrimaryTextBlock	INTECH U.S. Core Fund seeks long-term growth of capital.
Expense [Heading]	rr_ExpenseHeading	FEES AND EXPENSES OF THE FUND
Expense Narrative [Text Block]	rr_ExpenseNarrativeTextBlock	This table describes the fees and expenses that you may pay if you buy and hold Shares of the Fund.
Operating Expenses Caption [Text]	rr_OperatingExpensesCaption	ANNUAL FUND OPERATING EXPENSES (expenses that you pay each year as a percentage of the value of your investment)
Portfolio Turnover [Heading]	rr_PortfolioTurnoverHeading	Portfolio Turnover:
Portfolio Turnover [Text Block]	rr_PortfolioTurnoverTextBlock	The Fund pays transaction costs, such as commissions, when it buys and sells securities (or “turns over” its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when Fund shares are held in a taxable account. These costs, which are not reflected in annual fund operating expenses or in the Example, affect the Fund’s performance. During the most recent fiscal year, the Fund’s portfolio turnover rate was 67% of the average value of its portfolio.
Portfolio Turnover, Rate	rr_PortfolioTurnoverRate	67.00%
Expense Example [Heading]	rr_ExpenseExampleHeading	EXAMPLE:
Expense Example by Year [Heading]	rr_ExpenseExampleByYearHeading	The Example assumes that you invest $10,000 in the Fund for the time periods indicated, reinvest all dividends and distributions, and then redeem all of your Shares at the end of each period. The Example also assumes that your investment has a 5% return each year and that the Fund’s operating expenses remain the same. Although your actual costs may be higher or lower, based on these assumptions your costs would be:
Expense Example Narrative [Text Block]	rr_ExpenseExampleNarrativeTextBlock	The Example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds.
Strategy [Heading]	rr_StrategyHeading	PRINCIPAL INVESTMENT STRATEGIES
Strategy Narrative [Text Block]	rr_StrategyNarrativeTextBlock	The Fund invests, under normal circumstances, at least 80% of its net assets in U.S. common stocks from the universe of the S&P 500® Index, utilizing INTECH’s mathematical investment process. The S&P 500® Index is an unmanaged index of 500 stocks that is generally representative of the performance of larger companies in the United States. The Fund pursues its investment objective by applying a mathematical investment process to construct an investment portfolio from the universe of common stocks within its named benchmark index. The goal of this process is to build a portfolio of stocks in a more efficient combination than the named benchmark index. The process seeks to capitalize on the natural volatility of the market by searching for stocks within the index that have high relative volatility (providing the potential for excess returns) but that essentially move in opposite directions or have low correlation to each other (providing the potential for lower relative risk). By constructing the portfolio in this manner and periodically rebalancing the portfolio to maintain potentially more efficient weightings, INTECH’s mathematical investment process seeks to create a portfolio that, over time, produces returns in excess of its named benchmark index with risks similar to that of the benchmark index. The rebalancing techniques used by INTECH may result in a higher portfolio turnover compared to a “buy and hold” fund strategy. The Fund may lend portfolio securities on a short-term or long-term basis, in an amount equal to up to 1/3 of its total assets as determined at the time of the loan origination.
Risk [Heading]	rr_RiskHeading	PRINCIPAL INVESTMENT RISKS
Risk Narrative [Text Block]	rr_RiskNarrativeTextBlock	The biggest risk is that the Fund’s returns will vary, and you could lose money. The Fund is designed for long-term investors seeking an equity portfolio, including common stocks. Common stocks tend to be more volatile than many other investment choices. Market Risk. The value of the Fund’s portfolio may decrease if the value of an individual company or security, or multiple companies or securities, in the portfolio decreases. Further, regardless of how well individual companies or securities perform, the value of the Fund’s portfolio could also decrease if there are deteriorating economic or market conditions. It is important to understand that the value of your investment may fall, sometimes sharply, in response to changes in the market, and you could lose money. Investment Process Risk. The proprietary mathematical investment process used by INTECH may not achieve the desired results. There is a risk that INTECH’s method of identifying stocks with higher volatility than the named benchmark index or its method of identifying stocks that tend to move in the same or opposite direction relative to each other (correlation) will not result in selecting stocks with continuing volatility or the expected correlation. In INTECH’s history, which spans more than 25 years, INTECH’s mathematical investment process has experienced periods of both underperformance and outperformance relative to an identified benchmark. Even when the proprietary mathematical investment process is working appropriately, INTECH expects that there will be periods of underperformance relative to the benchmark. On an occasional basis, INTECH makes changes to its mathematical investment process. These changes may result in changes to the portfolio, might not provide the intended results, and may adversely impact the Fund’s performance. Portfolio Turnover Risk. Increased portfolio turnover may result in higher costs, which may have a negative effect on the Fund’s performance. In addition, higher portfolio turnover may result in the acceleration of capital gains and the recognition of greater levels of short-term capital gains, which are taxed at ordinary federal income tax rates when distributed to shareholders. Securities Lending Risk. The Fund may seek to earn additional income through lending its securities to certain qualified broker-dealers and institutions. There is the risk that when portfolio securities are lent, the securities may not be returned on a timely basis, and the Fund may experience delays and costs in recovering the security or gaining access to the collateral provided to the Fund to collateralize the loan. If the Fund is unable to recover a security on loan, the Fund may use the collateral to purchase replacement securities in the market. There is a risk that the value of the collateral could decrease below the cost of the replacement security by the time the replacement investment is made, resulting in a loss to the Fund. An investment in the Fund is not a bank deposit and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency.
Risk Lose Money [Text]	rr_RiskLoseMoney	The biggest risk is that the Fund’s returns will vary, and you could lose money.
Risk Not Insured Depository Institution [Text]	rr_RiskNotInsuredDepositoryInstitution	An investment in the Fund is not a bank deposit and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency.
Bar Chart and Performance Table [Heading]	rr_BarChartAndPerformanceTableHeading	PERFORMANCE INFORMATION
Performance Narrative [Text Block]	rr_PerformanceNarrativeTextBlock	The following information provides some indication of the risks of investing in the Fund by showing how the Fund’s performance has varied over time. Class D Shares of the Fund commenced operations on February 16, 2010, as a result of the restructuring of Class J Shares, the predecessor share class. The performance shown for Class D Shares for periods prior to February 16, 2010, reflects the performance of the Fund’s former Class J Shares, calculated using the fees and expenses in effect during the periods shown, net of any applicable fee and expense limitations or waivers. If Class D Shares of the Fund had been available during periods prior to February 16, 2010, the performance shown may have been different. The performance shown for periods following the Fund’s commencement of Class D Shares reflects the fees and expenses of Class D Shares, net of any applicable fee and expense limitations or waivers. The bar chart depicts the change in performance from year to year during the periods indicated. The table compares the Fund’s average annual returns for the periods indicated to a broad-based securities market index. The index is not actively managed and is not available for direct investment. All figures assume reinvestment of dividends and distributions. For certain periods, the Fund’s performance reflects the effect of expense waivers. Without the effect of these expense waivers, the performance shown would have been lower. The Fund’s past performance (before and after taxes) does not necessarily indicate how it will perform in the future. Updated performance information is available at janus.com/allfunds or by calling 1-800-525-3713.
Performance Information Illustrates Variability of Returns [Text]	rr_PerformanceInformationIllustratesVariabilityOfReturns	The following information provides some indication of the risks of investing in the Fund by showing how the Fund’s performance has varied over time. The bar chart depicts the change in performance from year to year during the periods indicated.
Performance Additional Market Index [Text]	rr_PerformanceAdditionalMarketIndex	The table compares the Fund’s average annual returns for the periods indicated to a broad-based securities market index. The index is not actively managed and is not available for direct investment. All figures assume reinvestment of dividends and distributions.
Performance Availability Phone [Text]	rr_PerformanceAvailabilityPhone	1-800-525-3713
Performance Availability Website Address [Text]	rr_PerformanceAvailabilityWebSiteAddress	janus.com/allfunds
Performance Past Does Not Indicate Future [Text]	rr_PerformancePastDoesNotIndicateFuture	The Fund’s past performance (before and after taxes) does not necessarily indicate how it will perform in the future.
Bar Chart [Heading]	rr_BarChartHeading	Annual Total Returns for Class D Shares (calendar year-end)
Bar Chart Closing [Text Block]	rr_BarChartClosingTextBlock	Best Quarter:  Second Quarter 2009  14.79%          Worst Quarter:  Fourth Quarter 2008  −21.49%
Year to Date Return, Label	rr_YearToDateReturnLabel	The Fund’s year-to-date return as of the calendar quarter ended September 30, 2013 was 21.75%.
Performance Table Heading	rr_PerformanceTableHeading	Average Annual Total Returns (periods ended 12/31/12)
Performance Table Uses Highest Federal Rate	rr_PerformanceTableUsesHighestFederalRate	After-tax returns are calculated using the historically highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes.
Performance Table Not Relevant to Tax Deferred	rr_PerformanceTableNotRelevantToTaxDeferred	Actual after-tax returns depend on your individual tax situation and may differ from those shown in the preceding table. The after-tax return information shown above does not apply to Fund shares held through a tax-deferred account, such as a 401(k) plan or an IRA.
Performance Table Narrative	rr_PerformanceTableNarrativeTextBlock	The Standard & Poor’s (“S&P”) 500® Index is a commonly recognized, market-capitalization weighted index of 500 widely held equity securities, designed to measure broad U.S. equity performance. This index is used to calculate the performance fee adjustment. After-tax returns are calculated using distributions for the Fund’s Class D Shares for the periods following February 16, 2010; and for the Fund’s Class J Shares, the predecessor share class, for the periods prior to February 16, 2010. If Class D Shares of the Fund had been available during these earlier periods, distributions may have been different and thus, after-tax returns may have been different from those shown. After-tax returns are calculated using the historically highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes. Actual after-tax returns depend on your individual tax situation and may differ from those shown in the preceding table. The after-tax return information shown above does not apply to Fund shares held through a tax-deferred account, such as a 401(k) plan or an IRA.
Performance Table Closing [Text Block]	rr_PerformanceTableClosingTextBlock	Updated performance information is available at janus.com/allfunds or by calling 1-800-525-3713.
INTECH U.S. Core Fund | Class D Shares | Class D
Risk/Return:	rr_RiskReturnAbstract
Operating Expenses Column [Text]	rr_OperatingExpensesColumnName	Class D
Management Fees (may adjust up or down)	rr_ManagementFeesOverAssets	0.60%
Other Expenses	rr_OtherExpensesOverAssets	0.25%
Total Annual Fund Operating Expenses	rr_ExpensesOverAssets	0.85%
Expense Example, By Year, Column [Text]	rr_ExpenseExampleByYearColumnName	Class D Shares
1 Year	rr_ExpenseExampleYear01	$ 87
3 Years	rr_ExpenseExampleYear03	271
5 Years	rr_ExpenseExampleYear05	471
10 Years	rr_ExpenseExampleYear10	$ 1,049
2004	rr_AnnualReturn2004	17.68%
2005	rr_AnnualReturn2005	11.06%
2006	rr_AnnualReturn2006	11.37%
2007	rr_AnnualReturn2007	6.40%
2008	rr_AnnualReturn2008	(36.57%)
2009	rr_AnnualReturn2009	22.91%
2010	rr_AnnualReturn2010	16.38%
2011	rr_AnnualReturn2011	5.07%
2012	rr_AnnualReturn2012	14.66%
Bar Chart, Year to Date Return, Date	rr_BarChartYearToDateReturnDate	Sep. 30, 2013
Bar Chart, Year to Date Return	rr_BarChartYearToDateReturn	21.75%
Highest Quarterly Return, Label	rr_HighestQuarterlyReturnLabel	Best Quarter:
Highest Quarterly Return, Date	rr_BarChartHighestQuarterlyReturnDate	Jun. 30, 2009
Highest Quarterly Return	rr_BarChartHighestQuarterlyReturn	14.79%
Lowest Quarterly Return, Label	rr_LowestQuarterlyReturnLabel	Worst Quarter:
Lowest Quarterly Return, Date	rr_BarChartLowestQuarterlyReturnDate	Dec. 31, 2008
Lowest Quarterly Return	rr_BarChartLowestQuarterlyReturn	(21.49%)
INTECH U.S. Core Fund | Class D Shares | Return Before Taxes | Class D
Risk/Return:	rr_RiskReturnAbstract
Column	rr_AverageAnnualReturnColumnName	Class D Shares
Label	rr_AverageAnnualReturnLabel	Return Before Taxes
1 Year	rr_AverageAnnualReturnYear01	14.66%
5 Years	rr_AverageAnnualReturnYear05	1.80%
Since Inception	rr_AverageAnnualReturnSinceInception	8.49%
Inception Date	rr_AverageAnnualReturnInceptionDate	Feb. 28, 2003
INTECH U.S. Core Fund | Class D Shares | Return After Taxes on Distributions | Class D
Risk/Return:	rr_RiskReturnAbstract
Column	rr_AverageAnnualReturnColumnName	Class D Shares
Label	rr_AverageAnnualReturnLabel	Return After Taxes on Distributions
1 Year	rr_AverageAnnualReturnYear01	14.42%
5 Years	rr_AverageAnnualReturnYear05	1.58%
Since Inception	rr_AverageAnnualReturnSinceInception	7.81%
Inception Date	rr_AverageAnnualReturnInceptionDate	Feb. 28, 2003
INTECH U.S. Core Fund | Class D Shares | Return After Taxes on Distributions and Sale of Fund Shares | Class D
Risk/Return:	rr_RiskReturnAbstract
Column	rr_AverageAnnualReturnColumnName	Class D Shares
Label	rr_AverageAnnualReturnLabel	Return After Taxes on Distributions and Sale of Fund Shares
1 Year	rr_AverageAnnualReturnYear01	9.86%
5 Years	rr_AverageAnnualReturnYear05	1.49%
Since Inception	rr_AverageAnnualReturnSinceInception	7.34%
Inception Date	rr_AverageAnnualReturnInceptionDate	Feb. 28, 2003
INTECH U.S. Core Fund | Class D Shares | S&P 500® Index (reflects no deduction for expenses, fees, or taxes)
Risk/Return:	rr_RiskReturnAbstract
Label	rr_AverageAnnualReturnLabel	S&P 500® Index
1 Year	rr_AverageAnnualReturnYear01	16.00%
5 Years	rr_AverageAnnualReturnYear05	1.66%
Since Inception	rr_AverageAnnualReturnSinceInception	7.68%
Inception Date	rr_AverageAnnualReturnInceptionDate	Feb. 28, 2003

XML

Label	Element	Value
Risk/Return:	rr_RiskReturnAbstract
Registrant Name	dei_EntityRegistrantName	JANUS INVESTMENT FUND
Prospectus Date	rr_ProspectusDate	Oct. 28, 2013
INTECH Global Dividend Fund | Class A, C, S, I, T Shares
Risk/Return:	rr_RiskReturnAbstract
Risk/Return [Heading]	rr_RiskReturnHeading	FUND SUMMARY INTECH Global Dividend Fund
Objective [Heading]	rr_ObjectiveHeading	INVESTMENT OBJECTIVE
Objective, Primary [Text Block]	rr_ObjectivePrimaryTextBlock	INTECH Global Dividend Fund seeks long-term growth of capital and income.
Expense [Heading]	rr_ExpenseHeading	FEES AND EXPENSES OF THE FUND
Expense Narrative [Text Block]	rr_ExpenseNarrativeTextBlock	This table describes the fees and expenses that you may pay if you buy and hold Shares of the Fund. Each share class has different expenses, but represents an investment in the same Fund.
Shareholder Fees Caption [Text]	rr_ShareholderFeesCaption	SHAREHOLDER FEES (fees paid directly from your investment)
Operating Expenses Caption [Text]	rr_OperatingExpensesCaption	ANNUAL FUND OPERATING EXPENSES (expenses that you pay each year as a percentage of the value of your investment)
Fee Waiver or Reimbursement over Assets, Date of Termination	rr_FeeWaiverOrReimbursementOverAssetsDateOfTermination	November 1, 2014
Portfolio Turnover [Heading]	rr_PortfolioTurnoverHeading	Portfolio Turnover:
Portfolio Turnover [Text Block]	rr_PortfolioTurnoverTextBlock	The Fund pays transaction costs, such as commissions, when it buys and sells securities (or “turns over” its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when Fund shares are held in a taxable account. These costs, which are not reflected in annual fund operating expenses or in the Example, affect the Fund’s performance. During the most recent fiscal year, the Fund’s portfolio turnover rate was 116% of the average value of its portfolio.
Portfolio Turnover, Rate	rr_PortfolioTurnoverRate	116.00%
Expense Breakpoint Discounts [Text]	rr_ExpenseBreakpointDiscounts	For Class A Shares, you may qualify for sales charge discounts if you and your family invest, or agree to invest in the future, at least $50,000 in the Fund or in other Janus mutual funds. More information about these and other discounts, as well as eligibility requirements for each share class, is available from your financial professional and in the “Purchases” section on page 51 of the Fund’s Prospectus and in the “Purchases” section on page 70 of the Fund’s Statement of Additional Information.
Expense Breakpoint, Minimum Investment Required [Amount]	rr_ExpenseBreakpointMinimumInvestmentRequiredAmount	$ 50,000
Expense Example [Heading]	rr_ExpenseExampleHeading	EXAMPLE:
Expense Example by Year [Heading]	rr_ExpenseExampleByYearHeading	The Example assumes that you invest $10,000 in the Fund for the time periods indicated and reinvest all dividends and distributions. The Example also assumes that your investment has a 5% return each year and that the Fund’s operating expenses without waivers or recoupments (if applicable) remain the same. Although your actual costs may be higher or lower, based on these assumptions your costs would be:
Expense Example Narrative [Text Block]	rr_ExpenseExampleNarrativeTextBlock	The following Example is based on expenses without waivers. The Example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds.
Expense Example by, Year, Caption [Text]	rr_ExpenseExampleByYearCaption	If Shares are redeemed:
Expense Example, No Redemption, By Year, Caption [Text]	rr_ExpenseExampleNoRedemptionByYearCaption	If Shares are not redeemed:
Strategy [Heading]	rr_StrategyHeading	PRINCIPAL INVESTMENT STRATEGIES
Strategy Narrative [Text Block]	rr_StrategyNarrativeTextBlock	The Fund invests, under normal circumstances, at least 80% of its net assets in dividend-paying securities. The Fund invests primarily in common stocks from the universe of the Morgan Stanley Capital International (“MSCI”) World High Dividend Yield Index, utilizing INTECH’s mathematical investment process. The MSCI World High Dividend Yield Index is designed to reflect the performance of the high dividend yield securities contained within the broader MSCI World IndexSM. The Fund may also invest in foreign equity and debt securities. The Fund pursues its investment objective by applying a mathematical investment process to construct an investment portfolio from the universe of common stocks within its named benchmark index. The goal of this process is to build a portfolio of stocks in a more efficient combination than the named benchmark index. The process seeks to capitalize on the natural volatility of the market by searching for stocks within the index that have high relative volatility (providing the potential for excess returns) but that essentially move in opposite directions or have low correlation to each other (providing the potential for lower relative risk). By constructing the portfolio in this manner and periodically rebalancing the portfolio to maintain potentially more efficient weightings, INTECH’s mathematical investment process seeks to create a portfolio that, over time, produces returns in excess of its named benchmark index with risks similar to that of the benchmark index. The rebalancing techniques used by INTECH may result in a higher portfolio turnover compared to a “buy and hold” fund strategy. The Fund may lend portfolio securities on a short-term or long-term basis, in an amount equal to up to 1/3 of its total assets as determined at the time of the loan origination.
Risk [Heading]	rr_RiskHeading	PRINCIPAL INVESTMENT RISKS
Risk Narrative [Text Block]	rr_RiskNarrativeTextBlock	The biggest risk is that the Fund’s returns will vary, and you could lose money. The Fund is designed for long-term investors seeking an equity portfolio, including common stocks. Common stocks tend to be more volatile than many other investment choices. Foreign Exposure Risk. The Fund normally has significant exposure to foreign markets as a result of its investments in foreign securities, which can be more volatile than the U.S. markets. As a result, its returns and net asset value may be affected to a large degree by fluctuations in currency exchange rates or political or economic conditions in a particular country. In some foreign markets, there may not be protection against failure by other parties to complete transactions. It may not be possible for the Fund to repatriate capital, dividends, interest, and other income from a particular country or governmental entity. In addition, a market swing in one or more countries or regions where the Fund has invested a significant amount of its assets may have a greater effect on the Fund’s performance than it would in a more geographically diversified portfolio. To the extent the Fund invests in foreign debt securities, such investments are sensitive to changes in interest rates. Additionally, investments in securities of foreign governments involve the risk that a foreign government may not be willing or able to pay interest or repay principal when due. Eurozone Risk. A number of countries in the European Union (“EU”) have experienced severe economic and financial difficulties. As a result, financial markets in the EU have been subject to extreme volatility and declines in asset values and liquidity. Responses to these financial problems by European governments, central banks, and others, including austerity measures and reforms, may not work, may result in social unrest, and may limit future growth and economic recovery or have other unintended consequences. Further defaults or restructurings by governments and others of their debt could have additional adverse effects on economies, financial markets, and asset valuations around the world. To the extent that the Fund has exposure to European markets or to transactions tied to the value of the euro, these events could negatively affect the value and liquidity of the Fund’s investments. Dividend Risk. Companies that issue dividend-yielding securities are not required to continue to pay dividends on such securities. Therefore, there is the possibility that such companies could reduce or eliminate the payment of dividends in the future. Market Risk. The value of the Fund’s portfolio may decrease if the value of an individual company or security, or multiple companies or securities, in the portfolio decreases. Further, regardless of how well individual companies or securities perform, the value of the Fund’s portfolio could also decrease if there are deteriorating economic or market conditions. It is important to understand that the value of your investment may fall, sometimes sharply, in response to changes in the market, and you could lose money. Investment Process Risk. The proprietary mathematical investment process used by INTECH may not achieve the desired results. There is a risk that INTECH’s method of identifying stocks with higher volatility than the named benchmark index or its method of identifying stocks that tend to move in the same or opposite direction relative to each other (correlation) will not result in selecting stocks with continuing volatility or the expected correlation. In INTECH’s history, which spans more than 25 years, INTECH’s mathematical investment process has experienced periods of both underperformance and outperformance relative to an identified benchmark. Even when the proprietary mathematical investment process is working appropriately, INTECH expects that there will be periods of underperformance relative to the benchmark. On an occasional basis, INTECH makes changes to its mathematical investment process. These changes may result in changes to the portfolio, might not provide the intended results, and may adversely impact the Fund’s performance. Portfolio Turnover Risk. Increased portfolio turnover may result in higher costs, which may have a negative effect on the Fund’s performance. In addition, higher portfolio turnover may result in the acceleration of capital gains and the recognition of greater levels of short-term capital gains, which are taxed at ordinary federal income tax rates when distributed to shareholders. Securities Lending Risk. The Fund may seek to earn additional income through lending its securities to certain qualified broker-dealers and institutions. There is the risk that when portfolio securities are lent, the securities may not be returned on a timely basis, and the Fund may experience delays and costs in recovering the security or gaining access to the collateral provided to the Fund to collateralize the loan. If the Fund is unable to recover a security on loan, the Fund may use the collateral to purchase replacement securities in the market. There is a risk that the value of the collateral could decrease below the cost of the replacement security by the time the replacement investment is made, resulting in a loss to the Fund. An investment in the Fund is not a bank deposit and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency.
Risk Lose Money [Text]	rr_RiskLoseMoney	The biggest risk is that the Fund’s returns will vary, and you could lose money.
Risk Not Insured Depository Institution [Text]	rr_RiskNotInsuredDepositoryInstitution	An investment in the Fund is not a bank deposit and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency.
Bar Chart and Performance Table [Heading]	rr_BarChartAndPerformanceTableHeading	PERFORMANCE INFORMATION
Performance Narrative [Text Block]	rr_PerformanceNarrativeTextBlock	The following information provides some indication of the risks of investing in the Fund by showing how the Fund’s performance has varied over time. The bar chart depicts the Fund’s performance during the period indicated. The bar chart figures do not include any applicable sales charges that an investor may pay when they buy or sell Class A Shares or Class C Shares of the Fund. If sales charges were included, the returns would be lower. The table compares the Fund’s average annual returns for the periods indicated to broad-based securities market indices. The indices are not actively managed and are not available for direct investment. All figures assume reinvestment of dividends and distributions. For certain periods, the Fund’s performance reflects the effect of expense waivers. Without the effect of these expense waivers, the performance shown would have been lower. The Fund’s past performance (before and after taxes) does not necessarily indicate how it will perform in the future. Updated performance information is available at janus.com/advisor/mutual-funds or by calling 1-877-335-2687.
Performance Information Illustrates Variability of Returns [Text]	rr_PerformanceInformationIllustratesVariabilityOfReturns	The following information provides some indication of the risks of investing in the Fund by showing how the Fund’s performance has varied over time. The bar chart depicts the Fund’s performance during the period indicated.
Performance Additional Market Index [Text]	rr_PerformanceAdditionalMarketIndex	The table compares the Fund’s average annual returns for the periods indicated to broad-based securities market indices. The indices are not actively managed and are not available for direct investment. All figures assume reinvestment of dividends and distributions.
Performance Availability Phone [Text]	rr_PerformanceAvailabilityPhone	1-877-335-2687
Performance Availability Website Address [Text]	rr_PerformanceAvailabilityWebSiteAddress	janus.com/advisor/mutual-funds
Performance Past Does Not Indicate Future [Text]	rr_PerformancePastDoesNotIndicateFuture	The Fund’s past performance (before and after taxes) does not necessarily indicate how it will perform in the future.
Bar Chart [Heading]	rr_BarChartHeading	Annual Total Returns for Class I Shares (calendar year-end)
Bar Chart Does Not Reflect Sales Loads [Text]	rr_BarChartDoesNotReflectSalesLoads	The bar chart figures do not include any applicable sales charges that an investor may pay when they buy or sell Class A Shares or Class C Shares of the Fund. If sales charges were included, the returns would be lower.
Bar Chart Closing [Text Block]	rr_BarChartClosingTextBlock	Best Quarter:  Third Quarter 2012  5.98%          Worst Quarter:  Second Quarter 2012  −2.66%
Year to Date Return, Label	rr_YearToDateReturnLabel	The Fund’s year-to-date return as of the calendar quarter ended September 30, 2013 was 12.88%.
Performance Table Heading	rr_PerformanceTableHeading	Average Annual Total Returns (periods ended 12/31/12)
Performance Table Uses Highest Federal Rate	rr_PerformanceTableUsesHighestFederalRate	After-tax returns are calculated using the historically highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes.
Performance Table Not Relevant to Tax Deferred	rr_PerformanceTableNotRelevantToTaxDeferred	Actual after-tax returns depend on your individual tax situation and may differ from those shown in the preceding table. The after-tax return information shown above does not apply to Fund shares held through a tax-deferred account, such as a 401(k) plan or an IRA.
Performance Table One Class of after Tax Shown [Text]	rr_PerformanceTableOneClassOfAfterTaxShown	After-tax returns are only shown for Class I Shares of the Fund. After-tax returns for the other classes of Shares will vary from those shown for Class I Shares due to varying sales charges (as applicable), fees, and expenses among the classes.
Performance Table Narrative	rr_PerformanceTableNarrativeTextBlock	After-tax returns are calculated using the historically highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes. Actual after-tax returns depend on your individual tax situation and may differ from those shown in the preceding table. The after-tax return information shown above does not apply to Fund shares held through a tax-deferred account, such as a 401(k) plan or an IRA. After-tax returns are only shown for Class I Shares of the Fund. After-tax returns for the other classes of Shares will vary from those shown for Class I Shares due to varying sales charges (as applicable), fees, and expenses among the classes.
Performance Table Closing [Text Block]	rr_PerformanceTableClosingTextBlock	Updated performance information is available at janus.com/advisor/mutual-funds or by calling 1-877-335-2687.
INTECH Global Dividend Fund | Class A, C, S, I, T Shares | Class A
Risk/Return:	rr_RiskReturnAbstract
Shareholder Fees Column [Text]	rr_ShareholderFeesColumnName	Class A
Maximum Sales Charge (load) Imposed on Purchases (as a percentage of offering price)	rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice	5.75%
Maximum Deferred Sales Charge (load) (as a percentage of the lower of original purchase price or redemption proceeds)	rr_MaximumDeferredSalesChargeOverOther	none
Operating Expenses Column [Text]	rr_OperatingExpensesColumnName	Class A
Management Fees	rr_ManagementFeesOverAssets	0.55%
Distribution/Service (12b-1) Fees	rr_DistributionAndService12b1FeesOverAssets	0.25%
Other Expenses	rr_OtherExpensesOverAssets	1.89%
Total Annual Fund Operating Expenses	rr_ExpensesOverAssets	2.69%	[1]
Fee Waiver	rr_FeeWaiverOrReimbursementOverAssets	1.92%	[1]
Total Annual Fund Operating Expenses After Fee Waiver	rr_NetExpensesOverAssets	0.77%	[1]
Expense Example, By Year, Column [Text]	rr_ExpenseExampleByYearColumnName	Class A Shares
1 Year	rr_ExpenseExampleYear01	831
3 Years	rr_ExpenseExampleYear03	1,362
5 Years	rr_ExpenseExampleYear05	1,918
10 Years	rr_ExpenseExampleYear10	3,423
Expense Example, No Redemption, By Year, Column [Text]	rr_ExpenseExampleNoRedemptionByYearColumnName	Class A Shares
1 Year	rr_ExpenseExampleNoRedemptionYear01	831
3 Years	rr_ExpenseExampleNoRedemptionYear03	1,362
5 Years	rr_ExpenseExampleNoRedemptionYear05	1,918
10 Years	rr_ExpenseExampleNoRedemptionYear10	3,423
INTECH Global Dividend Fund | Class A, C, S, I, T Shares | Class C
Risk/Return:	rr_RiskReturnAbstract
Shareholder Fees Column [Text]	rr_ShareholderFeesColumnName	Class C
Maximum Sales Charge (load) Imposed on Purchases (as a percentage of offering price)	rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice	none
Maximum Deferred Sales Charge (load) (as a percentage of the lower of original purchase price or redemption proceeds)	rr_MaximumDeferredSalesChargeOverOther	1.00%
Operating Expenses Column [Text]	rr_OperatingExpensesColumnName	Class C
Management Fees	rr_ManagementFeesOverAssets	0.55%
Distribution/Service (12b-1) Fees	rr_DistributionAndService12b1FeesOverAssets	1.00%
Other Expenses	rr_OtherExpensesOverAssets	1.95%
Total Annual Fund Operating Expenses	rr_ExpensesOverAssets	3.50%	[1]
Fee Waiver	rr_FeeWaiverOrReimbursementOverAssets	2.00%	[1]
Total Annual Fund Operating Expenses After Fee Waiver	rr_NetExpensesOverAssets	1.50%	[1]
Expense Example, By Year, Column [Text]	rr_ExpenseExampleByYearColumnName	Class C Shares
1 Year	rr_ExpenseExampleYear01	453
3 Years	rr_ExpenseExampleYear03	1,074
5 Years	rr_ExpenseExampleYear05	1,817
10 Years	rr_ExpenseExampleYear10	3,774
Expense Example, No Redemption, By Year, Column [Text]	rr_ExpenseExampleNoRedemptionByYearColumnName	Class C Shares
1 Year	rr_ExpenseExampleNoRedemptionYear01	353
3 Years	rr_ExpenseExampleNoRedemptionYear03	1,074
5 Years	rr_ExpenseExampleNoRedemptionYear05	1,817
10 Years	rr_ExpenseExampleNoRedemptionYear10	3,774
INTECH Global Dividend Fund | Class A, C, S, I, T Shares | Class S
Risk/Return:	rr_RiskReturnAbstract
Shareholder Fees Column [Text]	rr_ShareholderFeesColumnName	Class S
Maximum Sales Charge (load) Imposed on Purchases (as a percentage of offering price)	rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice	none
Maximum Deferred Sales Charge (load) (as a percentage of the lower of original purchase price or redemption proceeds)	rr_MaximumDeferredSalesChargeOverOther	none
Operating Expenses Column [Text]	rr_OperatingExpensesColumnName	Class S
Management Fees	rr_ManagementFeesOverAssets	0.55%
Distribution/Service (12b-1) Fees	rr_DistributionAndService12b1FeesOverAssets	0.25%
Other Expenses	rr_OtherExpensesOverAssets	2.16%
Total Annual Fund Operating Expenses	rr_ExpensesOverAssets	2.96%	[1]
Fee Waiver	rr_FeeWaiverOrReimbursementOverAssets	1.96%	[1]
Total Annual Fund Operating Expenses After Fee Waiver	rr_NetExpensesOverAssets	1.00%	[1]
Expense Example, By Year, Column [Text]	rr_ExpenseExampleByYearColumnName	Class S Shares
1 Year	rr_ExpenseExampleYear01	299
3 Years	rr_ExpenseExampleYear03	915
5 Years	rr_ExpenseExampleYear05	1,557
10 Years	rr_ExpenseExampleYear10	3,280
Expense Example, No Redemption, By Year, Column [Text]	rr_ExpenseExampleNoRedemptionByYearColumnName	Class S Shares
1 Year	rr_ExpenseExampleNoRedemptionYear01	299
3 Years	rr_ExpenseExampleNoRedemptionYear03	915
5 Years	rr_ExpenseExampleNoRedemptionYear05	1,557
10 Years	rr_ExpenseExampleNoRedemptionYear10	3,280
INTECH Global Dividend Fund | Class A, C, S, I, T Shares | Class I
Risk/Return:	rr_RiskReturnAbstract
Shareholder Fees Column [Text]	rr_ShareholderFeesColumnName	Class I
Maximum Sales Charge (load) Imposed on Purchases (as a percentage of offering price)	rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice	none
Maximum Deferred Sales Charge (load) (as a percentage of the lower of original purchase price or redemption proceeds)	rr_MaximumDeferredSalesChargeOverOther	none
Operating Expenses Column [Text]	rr_OperatingExpensesColumnName	Class I
Management Fees	rr_ManagementFeesOverAssets	0.55%
Distribution/Service (12b-1) Fees	rr_DistributionAndService12b1FeesOverAssets	none
Other Expenses	rr_OtherExpensesOverAssets	1.90%
Total Annual Fund Operating Expenses	rr_ExpensesOverAssets	2.45%	[1]
Fee Waiver	rr_FeeWaiverOrReimbursementOverAssets	1.93%	[1]
Total Annual Fund Operating Expenses After Fee Waiver	rr_NetExpensesOverAssets	0.52%	[1]
Expense Example, By Year, Column [Text]	rr_ExpenseExampleByYearColumnName	Class I Shares
1 Year	rr_ExpenseExampleYear01	248
3 Years	rr_ExpenseExampleYear03	764
5 Years	rr_ExpenseExampleYear05	1,306
10 Years	rr_ExpenseExampleYear10	2,786
Expense Example, No Redemption, By Year, Column [Text]	rr_ExpenseExampleNoRedemptionByYearColumnName	Class I Shares
1 Year	rr_ExpenseExampleNoRedemptionYear01	248
3 Years	rr_ExpenseExampleNoRedemptionYear03	764
5 Years	rr_ExpenseExampleNoRedemptionYear05	1,306
10 Years	rr_ExpenseExampleNoRedemptionYear10	2,786
2012	rr_AnnualReturn2012	12.35%
Bar Chart, Year to Date Return, Date	rr_BarChartYearToDateReturnDate	Sep. 30, 2013
Bar Chart, Year to Date Return	rr_BarChartYearToDateReturn	12.88%
Highest Quarterly Return, Label	rr_HighestQuarterlyReturnLabel	Best Quarter:
Highest Quarterly Return, Date	rr_BarChartHighestQuarterlyReturnDate	Sep. 30, 2012
Highest Quarterly Return	rr_BarChartHighestQuarterlyReturn	5.98%
Lowest Quarterly Return, Label	rr_LowestQuarterlyReturnLabel	Worst Quarter:
Lowest Quarterly Return, Date	rr_BarChartLowestQuarterlyReturnDate	Jun. 30, 2012
Lowest Quarterly Return	rr_BarChartLowestQuarterlyReturn	(2.66%)
INTECH Global Dividend Fund | Class A, C, S, I, T Shares | Class T
Risk/Return:	rr_RiskReturnAbstract
Shareholder Fees Column [Text]	rr_ShareholderFeesColumnName	Class T
Maximum Sales Charge (load) Imposed on Purchases (as a percentage of offering price)	rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice	none
Maximum Deferred Sales Charge (load) (as a percentage of the lower of original purchase price or redemption proceeds)	rr_MaximumDeferredSalesChargeOverOther	none
Operating Expenses Column [Text]	rr_OperatingExpensesColumnName	Class T
Management Fees	rr_ManagementFeesOverAssets	0.55%
Distribution/Service (12b-1) Fees	rr_DistributionAndService12b1FeesOverAssets	none
Other Expenses	rr_OtherExpensesOverAssets	2.14%
Total Annual Fund Operating Expenses	rr_ExpensesOverAssets	2.69%	[1]
Fee Waiver	rr_FeeWaiverOrReimbursementOverAssets	1.94%	[1]
Total Annual Fund Operating Expenses After Fee Waiver	rr_NetExpensesOverAssets	0.75%	[1]
Expense Example, By Year, Column [Text]	rr_ExpenseExampleByYearColumnName	Class T Shares
1 Year	rr_ExpenseExampleYear01	272
3 Years	rr_ExpenseExampleYear03	835
5 Years	rr_ExpenseExampleYear05	1,425
10 Years	rr_ExpenseExampleYear10	3,022
Expense Example, No Redemption, By Year, Column [Text]	rr_ExpenseExampleNoRedemptionByYearColumnName	Class T Shares
1 Year	rr_ExpenseExampleNoRedemptionYear01	272
3 Years	rr_ExpenseExampleNoRedemptionYear03	835
5 Years	rr_ExpenseExampleNoRedemptionYear05	1,425
10 Years	rr_ExpenseExampleNoRedemptionYear10	$ 3,022
INTECH Global Dividend Fund | Class A, C, S, I, T Shares | Return Before Taxes | Class A
Risk/Return:	rr_RiskReturnAbstract
Column	rr_AverageAnnualReturnColumnName	Class A Shares
Label	rr_AverageAnnualReturnLabel	Return Before Taxes	[2]
1 Year	rr_AverageAnnualReturnYear01	5.59%
Since Inception	rr_AverageAnnualReturnSinceInception	8.50%
Inception Date	rr_AverageAnnualReturnInceptionDate	Dec. 15, 2011
INTECH Global Dividend Fund | Class A, C, S, I, T Shares | Return Before Taxes | Class C
Risk/Return:	rr_RiskReturnAbstract
Column	rr_AverageAnnualReturnColumnName	Class C Shares
Label	rr_AverageAnnualReturnLabel	Return Before Taxes	[3]
1 Year	rr_AverageAnnualReturnYear01	10.10%
Since Inception	rr_AverageAnnualReturnSinceInception	13.98%
Inception Date	rr_AverageAnnualReturnInceptionDate	Dec. 15, 2011
INTECH Global Dividend Fund | Class A, C, S, I, T Shares | Return Before Taxes | Class S
Risk/Return:	rr_RiskReturnAbstract
Column	rr_AverageAnnualReturnColumnName	Class S Shares
Label	rr_AverageAnnualReturnLabel	Return Before Taxes
1 Year	rr_AverageAnnualReturnYear01	11.73%
Since Inception	rr_AverageAnnualReturnSinceInception	14.53%
Inception Date	rr_AverageAnnualReturnInceptionDate	Dec. 15, 2011
INTECH Global Dividend Fund | Class A, C, S, I, T Shares | Return Before Taxes | Class I
Risk/Return:	rr_RiskReturnAbstract
Column	rr_AverageAnnualReturnColumnName	Class I Shares
Label	rr_AverageAnnualReturnLabel	Return Before Taxes
1 Year	rr_AverageAnnualReturnYear01	12.35%
Since Inception	rr_AverageAnnualReturnSinceInception	15.14%
Inception Date	rr_AverageAnnualReturnInceptionDate	Dec. 15, 2011
INTECH Global Dividend Fund | Class A, C, S, I, T Shares | Return Before Taxes | Class T
Risk/Return:	rr_RiskReturnAbstract
Column	rr_AverageAnnualReturnColumnName	Class T Shares
Label	rr_AverageAnnualReturnLabel	Return Before Taxes
1 Year	rr_AverageAnnualReturnYear01	12.05%
Since Inception	rr_AverageAnnualReturnSinceInception	14.84%
Inception Date	rr_AverageAnnualReturnInceptionDate	Dec. 15, 2011
INTECH Global Dividend Fund | Class A, C, S, I, T Shares | Return After Taxes on Distributions | Class I
Risk/Return:	rr_RiskReturnAbstract
Column	rr_AverageAnnualReturnColumnName	Class I Shares
Label	rr_AverageAnnualReturnLabel	Return After Taxes on Distributions
1 Year	rr_AverageAnnualReturnYear01	11.63%
Since Inception	rr_AverageAnnualReturnSinceInception	14.39%
Inception Date	rr_AverageAnnualReturnInceptionDate	Dec. 15, 2011
INTECH Global Dividend Fund | Class A, C, S, I, T Shares | Return After Taxes on Distributions and Sale of Fund Shares | Class I
Risk/Return:	rr_RiskReturnAbstract
Column	rr_AverageAnnualReturnColumnName	Class I Shares
Label	rr_AverageAnnualReturnLabel	Return After Taxes on Distributions and Sale of Fund Shares
1 Year	rr_AverageAnnualReturnYear01	8.63%
Since Inception	rr_AverageAnnualReturnSinceInception	12.67%
Inception Date	rr_AverageAnnualReturnInceptionDate	Dec. 15, 2011
INTECH Global Dividend Fund | Class A, C, S, I, T Shares | Morgan Stanley Capital International World Index℠ (net of foreign withholding taxes) (reflects no deduction for expenses, fees, or taxes, except foreign withholding taxes)
Risk/Return:	rr_RiskReturnAbstract
Label	rr_AverageAnnualReturnLabel	Morgan Stanley Capital International World IndexSM (net of foreign withholding taxes)
1 Year	rr_AverageAnnualReturnYear01	15.83%
Since Inception	rr_AverageAnnualReturnSinceInception	19.02%
Inception Date	rr_AverageAnnualReturnInceptionDate	Dec. 15, 2011
INTECH Global Dividend Fund | Class A, C, S, I, T Shares | Morgan Stanley Capital International World High Dividend Yield Index (net of foreign withholding taxes) (reflects no deduction for expenses, fees, or taxes, except foreign withholding taxes)
Risk/Return:	rr_RiskReturnAbstract
Label	rr_AverageAnnualReturnLabel	Morgan Stanley Capital International World High Dividend Yield Index (net of foreign withholding taxes)
1 Year	rr_AverageAnnualReturnYear01	12.24%
Since Inception	rr_AverageAnnualReturnSinceInception	15.80%
Inception Date	rr_AverageAnnualReturnInceptionDate	Dec. 15, 2011

[1] Janus Capital has contractually agreed to waive its investment advisory fee and/or reimburse Fund expenses to the extent that the Fund’s total annual fund operating expenses (excluding the distribution and shareholder servicing fees – applicable to Class A Shares, Class C Shares, and Class S Shares; administrative services fees payable pursuant to the Transfer Agency Agreement; brokerage commissions; interest; dividends; taxes; acquired fund fees and expenses; and extraordinary expenses) exceed 0.50% until at least November 1, 2014. The contractual waiver may be terminated or modified prior to this date only at the discretion of the Board of Trustees. For a period of three years subsequent to the Fund’s commencement of operations (December 15, 2011), Janus Capital may recover from the Fund fees and expenses previously waived or reimbursed, which could then be considered a deferral, if the Fund’s expense ratio, including recovered expenses, falls below the expense limit.

[2] Calculated assuming maximum permitted sales loads.

[3] The one year return is calculated to include the contingent deferred sales charge.

XML

Label	Element	Value
Risk/Return:	rr_RiskReturnAbstract
Registrant Name	dei_EntityRegistrantName	JANUS INVESTMENT FUND
Prospectus Date	rr_ProspectusDate	Oct. 28, 2013
INTECH U.S. Growth Fund | Class A, C, S, I, T Shares
Risk/Return:	rr_RiskReturnAbstract
Risk/Return [Heading]	rr_RiskReturnHeading	FUND SUMMARY INTECH U.S. Growth Fund
Objective [Heading]	rr_ObjectiveHeading	INVESTMENT OBJECTIVE
Objective, Primary [Text Block]	rr_ObjectivePrimaryTextBlock	INTECH U.S. Growth Fund seeks long-term growth of capital.
Expense [Heading]	rr_ExpenseHeading	FEES AND EXPENSES OF THE FUND
Expense Narrative [Text Block]	rr_ExpenseNarrativeTextBlock	This table describes the fees and expenses that you may pay if you buy and hold Shares of the Fund. Each share class has different expenses, but represents an investment in the same Fund.
Shareholder Fees Caption [Text]	rr_ShareholderFeesCaption	SHAREHOLDER FEES (fees paid directly from your investment)
Operating Expenses Caption [Text]	rr_OperatingExpensesCaption	ANNUAL FUND OPERATING EXPENSES (expenses that you pay each year as a percentage of the value of your investment)
Portfolio Turnover [Heading]	rr_PortfolioTurnoverHeading	Portfolio Turnover:
Portfolio Turnover [Text Block]	rr_PortfolioTurnoverTextBlock	The Fund pays transaction costs, such as commissions, when it buys and sells securities (or “turns over” its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when Fund shares are held in a taxable account. These costs, which are not reflected in annual fund operating expenses or in the Example, affect the Fund’s performance. During the most recent fiscal year, the Fund’s portfolio turnover rate was 81% of the average value of its portfolio.
Portfolio Turnover, Rate	rr_PortfolioTurnoverRate	81.00%
Expense Breakpoint Discounts [Text]	rr_ExpenseBreakpointDiscounts	For Class A Shares, you may qualify for sales charge discounts if you and your family invest, or agree to invest in the future, at least $50,000 in the Fund or in other Janus mutual funds. More information about these and other discounts, as well as eligibility requirements for each share class, is available from your financial professional and in the “Purchases” section on page 51 of the Fund’s Prospectus and in the “Purchases” section on page 70 of the Fund’s Statement of Additional Information.
Expense Breakpoint, Minimum Investment Required [Amount]	rr_ExpenseBreakpointMinimumInvestmentRequiredAmount	$ 50,000
Expense Example [Heading]	rr_ExpenseExampleHeading	EXAMPLE:
Expense Example by Year [Heading]	rr_ExpenseExampleByYearHeading	The Example assumes that you invest $10,000 in the Fund for the time periods indicated and reinvest all dividends and distributions. The Example also assumes that your investment has a 5% return each year and that the Fund’s operating expenses remain the same. Although your actual costs may be higher or lower, based on these assumptions your costs would be:
Expense Example Narrative [Text Block]	rr_ExpenseExampleNarrativeTextBlock	The Example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds.
Expense Example by, Year, Caption [Text]	rr_ExpenseExampleByYearCaption	If Shares are redeemed:
Expense Example, No Redemption, By Year, Caption [Text]	rr_ExpenseExampleNoRedemptionByYearCaption	If Shares are not redeemed:
Strategy [Heading]	rr_StrategyHeading	PRINCIPAL INVESTMENT STRATEGIES
Strategy Narrative [Text Block]	rr_StrategyNarrativeTextBlock	The Fund invests, under normal circumstances, at least 80% of its net assets in U.S. common stocks from the universe of the Russell 1000® Growth Index, utilizing INTECH’s mathematical investment process. The Russell 1000® Growth Index is an unmanaged index that measures the performance of those Russell 1000 companies with higher price-to-book ratios and higher forecasted growth values. The Fund pursues its investment objective by applying a mathematical investment process to construct an investment portfolio from the universe of common stocks within its named benchmark index. The goal of this process is to build a portfolio of stocks in a more efficient combination than the named benchmark index. The process seeks to capitalize on the natural volatility of the market by searching for stocks within the index that have high relative volatility (providing the potential for excess returns) but that essentially move in opposite directions or have low correlation to each other (providing the potential for lower relative risk). By constructing the portfolio in this manner and periodically rebalancing the portfolio to maintain potentially more efficient weightings, INTECH’s mathematical investment process seeks to create a portfolio that, over time, produces returns in excess of its named benchmark index with risks similar to that of the benchmark index. The rebalancing techniques used by INTECH may result in a higher portfolio turnover compared to a “buy and hold” fund strategy. The Fund may lend portfolio securities on a short-term or long-term basis, in an amount equal to up to 1/3 of its total assets as determined at the time of the loan origination.
Risk [Heading]	rr_RiskHeading	PRINCIPAL INVESTMENT RISKS
Risk Narrative [Text Block]	rr_RiskNarrativeTextBlock	The biggest risk is that the Fund’s returns will vary, and you could lose money. The Fund is designed for long-term investors seeking an equity portfolio, including common stocks. Common stocks tend to be more volatile than many other investment choices. Growth Securities Risk. Securities of companies perceived to be “growth” companies may be more volatile than other stocks and may involve special risks. If a company’s growth potential is not realized, the securities purchased may not perform as expected, reducing the Fund’s returns. In addition, because different types of stocks tend to shift in and out of favor depending on market and economic conditions, “growth” stocks may perform differently from the market as a whole and other types of securities. Market Risk. The value of the Fund’s portfolio may decrease if the value of an individual company or security, or multiple companies or securities, in the portfolio decreases. Further, regardless of how well individual companies or securities perform, the value of the Fund’s portfolio could also decrease if there are deteriorating economic or market conditions. It is important to understand that the value of your investment may fall, sometimes sharply, in response to changes in the market, and you could lose money. Investment Process Risk. The proprietary mathematical investment process used by INTECH may not achieve the desired results. There is a risk that INTECH’s method of identifying stocks with higher volatility than the named benchmark index or its method of identifying stocks that tend to move in the same or opposite direction relative to each other (correlation) will not result in selecting stocks with continuing volatility or the expected correlation. In INTECH’s history, which spans more than 25 years, INTECH’s mathematical investment process has experienced periods of both underperformance and outperformance relative to an identified benchmark. Even when the proprietary mathematical investment process is working appropriately, INTECH expects that there will be periods of underperformance relative to the benchmark. On an occasional basis, INTECH makes changes to its mathematical investment process. These changes may result in changes to the portfolio, might not provide the intended results, and may adversely impact the Fund’s performance. Portfolio Turnover Risk. Increased portfolio turnover may result in higher costs, which may have a negative effect on the Fund’s performance. In addition, higher portfolio turnover may result in the acceleration of capital gains and the recognition of greater levels of short-term capital gains, which are taxed at ordinary federal income tax rates when distributed to shareholders. Securities Lending Risk. The Fund may seek to earn additional income through lending its securities to certain qualified broker-dealers and institutions. There is the risk that when portfolio securities are lent, the securities may not be returned on a timely basis, and the Fund may experience delays and costs in recovering the security or gaining access to the collateral provided to the Fund to collateralize the loan. If the Fund is unable to recover a security on loan, the Fund may use the collateral to purchase replacement securities in the market. There is a risk that the value of the collateral could decrease below the cost of the replacement security by the time the replacement investment is made, resulting in a loss to the Fund. An investment in the Fund is not a bank deposit and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency.
Risk Lose Money [Text]	rr_RiskLoseMoney	The biggest risk is that the Fund’s returns will vary, and you could lose money.
Risk Not Insured Depository Institution [Text]	rr_RiskNotInsuredDepositoryInstitution	An investment in the Fund is not a bank deposit and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency.
Bar Chart and Performance Table [Heading]	rr_BarChartAndPerformanceTableHeading	PERFORMANCE INFORMATION
Performance Narrative [Text Block]	rr_PerformanceNarrativeTextBlock	The following information provides some indication of the risks of investing in the Fund by showing how the Fund’s performance has varied over time. Class S Shares, Class A Shares, Class C Shares, and Class I Shares of the Fund commenced operations on July 6, 2009, after the reorganization of each corresponding class of shares of Janus Adviser INTECH Risk-Managed Growth Fund (“JAD predecessor fund”) into each respective share class of the Fund. Class T Shares of the Fund commenced operations on July 6, 2009. The performance shown for Class S Shares for periods prior to July 6, 2009, reflects the historical performance of the JAD predecessor fund’s Class S Shares prior to the reorganization, calculated using the fees and expenses of the JAD predecessor fund’s Class S Shares, net of any applicable fee and expense limitations or waivers. The performance shown for Class A Shares reflects the performance of the JAD predecessor fund’s Class A Shares from September 30, 2004 to July 6, 2009 (prior to the reorganization), calculated using the fees and expenses of Class A Shares of the JAD predecessor fund, net of any applicable fee and expense limitations or waivers. Performance shown for certain periods prior to September 30, 2004 reflects the historical performance of the JAD predecessor fund’s Class S Shares (formerly named Class I Shares), calculated using the fees and expenses of Class S Shares of the JAD predecessor fund, net of any applicable fee and expense limitations or waivers. The performance shown for Class C Shares for periods prior to July 6, 2009, reflects the historical performance of the JAD predecessor fund’s Class C Shares prior to the reorganization, calculated using the fees and expenses of the JAD predecessor fund’s Class C Shares, net of any applicable fee and expense limitations or waivers. The performance shown for Class I Shares reflects the performance of the JAD predecessor fund’s Class I Shares from November 28, 2005 to July 6, 2009 (prior to the reorganization), calculated using the fees and expenses of Class I Shares of the JAD predecessor fund, net of any applicable fee and expense limitations or waivers. Performance shown for certain periods prior to November 28, 2005 reflects the historical performance of the JAD predecessor fund’s Class S Shares (formerly named Class I Shares), calculated using the fees and expenses of Class S Shares of the JAD predecessor fund, net of any applicable fee and expense limitations or waivers. The performance shown for Class T Shares for periods prior to July 6, 2009, reflects the historical performance of the JAD predecessor fund’s Class S Shares prior to the reorganization, calculated using the fees and expenses of Class S Shares, net of any applicable fee and expense limitations or waivers. If Class A Shares, Class I Shares, and Class T Shares of the Fund had been available during periods prior to July 6, 2009, the performance shown for each respective share class may have been different. The performance shown for periods following the Fund’s commencement of Class S Shares, Class A Shares, Class C Shares, Class I Shares, and Class T Shares reflects the fees and expenses of each respective share class, net of any applicable fee and expense limitations or waivers. The bar chart depicts the change in performance from year to year during the periods indicated. The bar chart figures do not include any applicable sales charges that an investor may pay when they buy or sell Class A Shares or Class C Shares of the Fund. If sales charges were included, the returns would be lower. The table compares the Fund’s average annual returns for the periods indicated to a broad-based securities market index. The index is not actively managed and is not available for direct investment. All figures assume reinvestment of dividends and distributions. For certain periods, the Fund’s performance reflects the effect of expense waivers. Without the effect of these expense waivers, the performance shown would have been lower. The Fund’s past performance (before and after taxes) does not necessarily indicate how it will perform in the future. Updated performance information is available at janus.com/advisor/mutual-funds or by calling 1-877-335-2687.
Performance Information Illustrates Variability of Returns [Text]	rr_PerformanceInformationIllustratesVariabilityOfReturns	The following information provides some indication of the risks of investing in the Fund by showing how the Fund’s performance has varied over time. The bar chart depicts the change in performance from year to year during the periods indicated.
Performance Additional Market Index [Text]	rr_PerformanceAdditionalMarketIndex	The table compares the Fund’s average annual returns for the periods indicated to a broad-based securities market index. The index is not actively managed and is not available for direct investment. All figures assume reinvestment of dividends and distributions.
Performance Availability Phone [Text]	rr_PerformanceAvailabilityPhone	1-877-335-2687
Performance Availability Website Address [Text]	rr_PerformanceAvailabilityWebSiteAddress	janus.com/advisor/mutual-funds
Performance Past Does Not Indicate Future [Text]	rr_PerformancePastDoesNotIndicateFuture	The Fund’s past performance (before and after taxes) does not necessarily indicate how it will perform in the future.
Bar Chart [Heading]	rr_BarChartHeading	Annual Total Returns for Class S Shares (calendar year-end)
Bar Chart Does Not Reflect Sales Loads [Text]	rr_BarChartDoesNotReflectSalesLoads	The bar chart figures do not include any applicable sales charges that an investor may pay when they buy or sell Class A Shares or Class C Shares of the Fund. If sales charges were included, the returns would be lower.
Bar Chart Closing [Text Block]	rr_BarChartClosingTextBlock	Best Quarter:  Second Quarter 2009  15.04%          Worst Quarter:  Fourth Quarter 2008  −25.11%
Year to Date Return, Label	rr_YearToDateReturnLabel	The Fund’s year-to-date return as of the calendar quarter ended September 30, 2013 was 20.79%.
Performance Table Heading	rr_PerformanceTableHeading	Average Annual Total Returns (periods ended 12/31/12)
Performance Table Uses Highest Federal Rate	rr_PerformanceTableUsesHighestFederalRate	After-tax returns are calculated using the historically highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes.
Performance Table Not Relevant to Tax Deferred	rr_PerformanceTableNotRelevantToTaxDeferred	Actual after-tax returns depend on your individual tax situation and may differ from those shown in the preceding table. The after-tax return information shown above does not apply to Fund shares held through a tax-deferred account, such as a 401(k) plan or an IRA.
Performance Table One Class of after Tax Shown [Text]	rr_PerformanceTableOneClassOfAfterTaxShown	After-tax returns are only shown for Class S Shares of the Fund. After-tax returns for the other classes of Shares will vary from those shown for Class S Shares due to varying sales charges (as applicable), fees, and expenses among the classes.
Performance Table Narrative	rr_PerformanceTableNarrativeTextBlock	After-tax returns are calculated using distributions for the Fund’s Class S Shares for periods following July 6, 2009; and for the JAD predecessor fund’s Class S Shares (formerly named Class I Shares) for periods prior to July 6, 2009. After-tax returns are calculated using the historically highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes. Actual after-tax returns depend on your individual tax situation and may differ from those shown in the preceding table. The after-tax return information shown above does not apply to Fund shares held through a tax-deferred account, such as a 401(k) plan or an IRA. After-tax returns are only shown for Class S Shares of the Fund. After-tax returns for the other classes of Shares will vary from those shown for Class S Shares due to varying sales charges (as applicable), fees, and expenses among the classes.
Performance Table Closing [Text Block]	rr_PerformanceTableClosingTextBlock	Updated performance information is available at janus.com/advisor/mutual-funds or by calling 1-877-335-2687.
INTECH U.S. Growth Fund | Class A, C, S, I, T Shares | Class A
Risk/Return:	rr_RiskReturnAbstract
Shareholder Fees Column [Text]	rr_ShareholderFeesColumnName	Class A
Maximum Sales Charge (load) Imposed on Purchases (as a percentage of offering price)	rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice	5.75%
Maximum Deferred Sales Charge (load) (as a percentage of the lower of original purchase price or redemption proceeds)	rr_MaximumDeferredSalesChargeOverOther	none
Operating Expenses Column [Text]	rr_OperatingExpensesColumnName	Class A
Management Fees	rr_ManagementFeesOverAssets	0.50%
Distribution/Service (12b-1) Fees	rr_DistributionAndService12b1FeesOverAssets	0.25%
Other Expenses	rr_OtherExpensesOverAssets	0.15%
Total Annual Fund Operating Expenses	rr_ExpensesOverAssets	0.90%
Expense Example, By Year, Column [Text]	rr_ExpenseExampleByYearColumnName	Class A Shares
1 Year	rr_ExpenseExampleYear01	662
3 Years	rr_ExpenseExampleYear03	845
5 Years	rr_ExpenseExampleYear05	1,045
10 Years	rr_ExpenseExampleYear10	1,619
Expense Example, No Redemption, By Year, Column [Text]	rr_ExpenseExampleNoRedemptionByYearColumnName	Class A Shares
1 Year	rr_ExpenseExampleNoRedemptionYear01	662
3 Years	rr_ExpenseExampleNoRedemptionYear03	845
5 Years	rr_ExpenseExampleNoRedemptionYear05	1,045
10 Years	rr_ExpenseExampleNoRedemptionYear10	1,619
INTECH U.S. Growth Fund | Class A, C, S, I, T Shares | Class C
Risk/Return:	rr_RiskReturnAbstract
Shareholder Fees Column [Text]	rr_ShareholderFeesColumnName	Class C
Maximum Sales Charge (load) Imposed on Purchases (as a percentage of offering price)	rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice	none
Maximum Deferred Sales Charge (load) (as a percentage of the lower of original purchase price or redemption proceeds)	rr_MaximumDeferredSalesChargeOverOther	1.00%
Operating Expenses Column [Text]	rr_OperatingExpensesColumnName	Class C
Management Fees	rr_ManagementFeesOverAssets	0.50%
Distribution/Service (12b-1) Fees	rr_DistributionAndService12b1FeesOverAssets	1.00%
Other Expenses	rr_OtherExpensesOverAssets	0.10%
Total Annual Fund Operating Expenses	rr_ExpensesOverAssets	1.60%
Expense Example, By Year, Column [Text]	rr_ExpenseExampleByYearColumnName	Class C Shares
1 Year	rr_ExpenseExampleYear01	263
3 Years	rr_ExpenseExampleYear03	505
5 Years	rr_ExpenseExampleYear05	871
10 Years	rr_ExpenseExampleYear10	1,900
Expense Example, No Redemption, By Year, Column [Text]	rr_ExpenseExampleNoRedemptionByYearColumnName	Class C Shares
1 Year	rr_ExpenseExampleNoRedemptionYear01	163
3 Years	rr_ExpenseExampleNoRedemptionYear03	505
5 Years	rr_ExpenseExampleNoRedemptionYear05	871
10 Years	rr_ExpenseExampleNoRedemptionYear10	1,900
INTECH U.S. Growth Fund | Class A, C, S, I, T Shares | Class S
Risk/Return:	rr_RiskReturnAbstract
Shareholder Fees Column [Text]	rr_ShareholderFeesColumnName	Class S
Maximum Sales Charge (load) Imposed on Purchases (as a percentage of offering price)	rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice	none
Maximum Deferred Sales Charge (load) (as a percentage of the lower of original purchase price or redemption proceeds)	rr_MaximumDeferredSalesChargeOverOther	none
Operating Expenses Column [Text]	rr_OperatingExpensesColumnName	Class S
Management Fees	rr_ManagementFeesOverAssets	0.50%
Distribution/Service (12b-1) Fees	rr_DistributionAndService12b1FeesOverAssets	0.25%
Other Expenses	rr_OtherExpensesOverAssets	0.31%
Total Annual Fund Operating Expenses	rr_ExpensesOverAssets	1.06%
Expense Example, By Year, Column [Text]	rr_ExpenseExampleByYearColumnName	Class S Shares
1 Year	rr_ExpenseExampleYear01	108
3 Years	rr_ExpenseExampleYear03	337
5 Years	rr_ExpenseExampleYear05	585
10 Years	rr_ExpenseExampleYear10	1,294
Expense Example, No Redemption, By Year, Column [Text]	rr_ExpenseExampleNoRedemptionByYearColumnName	Class S Shares
1 Year	rr_ExpenseExampleNoRedemptionYear01	108
3 Years	rr_ExpenseExampleNoRedemptionYear03	337
5 Years	rr_ExpenseExampleNoRedemptionYear05	585
10 Years	rr_ExpenseExampleNoRedemptionYear10	1,294
2004	rr_AnnualReturn2004	12.34%
2005	rr_AnnualReturn2005	6.90%
2006	rr_AnnualReturn2006	6.90%
2007	rr_AnnualReturn2007	10.30%
2008	rr_AnnualReturn2008	(42.71%)
2009	rr_AnnualReturn2009	32.84%
2010	rr_AnnualReturn2010	17.50%
2011	rr_AnnualReturn2011	1.73%
2012	rr_AnnualReturn2012	15.24%
Bar Chart, Year to Date Return, Date	rr_BarChartYearToDateReturnDate	Sep. 30, 2013
Bar Chart, Year to Date Return	rr_BarChartYearToDateReturn	20.79%
Highest Quarterly Return, Label	rr_HighestQuarterlyReturnLabel	Best Quarter:
Highest Quarterly Return, Date	rr_BarChartHighestQuarterlyReturnDate	Jun. 30, 2009
Highest Quarterly Return	rr_BarChartHighestQuarterlyReturn	15.04%
Lowest Quarterly Return, Label	rr_LowestQuarterlyReturnLabel	Worst Quarter:
Lowest Quarterly Return, Date	rr_BarChartLowestQuarterlyReturnDate	Dec. 31, 2008
Lowest Quarterly Return	rr_BarChartLowestQuarterlyReturn	(25.11%)
INTECH U.S. Growth Fund | Class A, C, S, I, T Shares | Class I
Risk/Return:	rr_RiskReturnAbstract
Shareholder Fees Column [Text]	rr_ShareholderFeesColumnName	Class I
Maximum Sales Charge (load) Imposed on Purchases (as a percentage of offering price)	rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice	none
Maximum Deferred Sales Charge (load) (as a percentage of the lower of original purchase price or redemption proceeds)	rr_MaximumDeferredSalesChargeOverOther	none
Operating Expenses Column [Text]	rr_OperatingExpensesColumnName	Class I
Management Fees	rr_ManagementFeesOverAssets	0.50%
Distribution/Service (12b-1) Fees	rr_DistributionAndService12b1FeesOverAssets	none
Other Expenses	rr_OtherExpensesOverAssets	0.08%
Total Annual Fund Operating Expenses	rr_ExpensesOverAssets	0.58%
Expense Example, By Year, Column [Text]	rr_ExpenseExampleByYearColumnName	Class I Shares
1 Year	rr_ExpenseExampleYear01	59
3 Years	rr_ExpenseExampleYear03	186
5 Years	rr_ExpenseExampleYear05	324
10 Years	rr_ExpenseExampleYear10	726
Expense Example, No Redemption, By Year, Column [Text]	rr_ExpenseExampleNoRedemptionByYearColumnName	Class I Shares
1 Year	rr_ExpenseExampleNoRedemptionYear01	59
3 Years	rr_ExpenseExampleNoRedemptionYear03	186
5 Years	rr_ExpenseExampleNoRedemptionYear05	324
10 Years	rr_ExpenseExampleNoRedemptionYear10	726
INTECH U.S. Growth Fund | Class A, C, S, I, T Shares | Class T
Risk/Return:	rr_RiskReturnAbstract
Shareholder Fees Column [Text]	rr_ShareholderFeesColumnName	Class T
Maximum Sales Charge (load) Imposed on Purchases (as a percentage of offering price)	rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice	none
Maximum Deferred Sales Charge (load) (as a percentage of the lower of original purchase price or redemption proceeds)	rr_MaximumDeferredSalesChargeOverOther	none
Operating Expenses Column [Text]	rr_OperatingExpensesColumnName	Class T
Management Fees	rr_ManagementFeesOverAssets	0.50%
Distribution/Service (12b-1) Fees	rr_DistributionAndService12b1FeesOverAssets	none
Other Expenses	rr_OtherExpensesOverAssets	0.31%
Total Annual Fund Operating Expenses	rr_ExpensesOverAssets	0.81%
Expense Example, By Year, Column [Text]	rr_ExpenseExampleByYearColumnName	Class T Shares
1 Year	rr_ExpenseExampleYear01	83
3 Years	rr_ExpenseExampleYear03	259
5 Years	rr_ExpenseExampleYear05	450
10 Years	rr_ExpenseExampleYear10	1,002
Expense Example, No Redemption, By Year, Column [Text]	rr_ExpenseExampleNoRedemptionByYearColumnName	Class T Shares
1 Year	rr_ExpenseExampleNoRedemptionYear01	83
3 Years	rr_ExpenseExampleNoRedemptionYear03	259
5 Years	rr_ExpenseExampleNoRedemptionYear05	450
10 Years	rr_ExpenseExampleNoRedemptionYear10	$ 1,002
INTECH U.S. Growth Fund | Class A, C, S, I, T Shares | Return Before Taxes | Class A
Risk/Return:	rr_RiskReturnAbstract
Column	rr_AverageAnnualReturnColumnName	Class A Shares
Label	rr_AverageAnnualReturnLabel	Return Before Taxes	[1]
1 Year	rr_AverageAnnualReturnYear01	8.69%
5 Years	rr_AverageAnnualReturnYear05	(0.05%)
Since Inception of Predecessor Fund	rr_AverageAnnualReturnSinceInception	5.95%
Inception Date	rr_AverageAnnualReturnInceptionDate	Jan. 02, 2003
INTECH U.S. Growth Fund | Class A, C, S, I, T Shares | Return Before Taxes | Class C
Risk/Return:	rr_RiskReturnAbstract
Column	rr_AverageAnnualReturnColumnName	Class C Shares
Label	rr_AverageAnnualReturnLabel	Return Before Taxes	[2]
1 Year	rr_AverageAnnualReturnYear01	13.35%
5 Years	rr_AverageAnnualReturnYear05	0.29%
Since Inception of Predecessor Fund	rr_AverageAnnualReturnSinceInception	5.76%
Inception Date	rr_AverageAnnualReturnInceptionDate	Jan. 02, 2003
INTECH U.S. Growth Fund | Class A, C, S, I, T Shares | Return Before Taxes | Class S
Risk/Return:	rr_RiskReturnAbstract
Column	rr_AverageAnnualReturnColumnName	Class S Shares
Label	rr_AverageAnnualReturnLabel	Return Before Taxes
1 Year	rr_AverageAnnualReturnYear01	15.24%
5 Years	rr_AverageAnnualReturnYear05	0.95%
Since Inception of Predecessor Fund	rr_AverageAnnualReturnSinceInception	6.38%
Inception Date	rr_AverageAnnualReturnInceptionDate	Jan. 02, 2003
INTECH U.S. Growth Fund | Class A, C, S, I, T Shares | Return Before Taxes | Class I
Risk/Return:	rr_RiskReturnAbstract
Column	rr_AverageAnnualReturnColumnName	Class I Shares
Label	rr_AverageAnnualReturnLabel	Return Before Taxes
1 Year	rr_AverageAnnualReturnYear01	15.70%
5 Years	rr_AverageAnnualReturnYear05	1.41%
Since Inception of Predecessor Fund	rr_AverageAnnualReturnSinceInception	6.38%
Inception Date	rr_AverageAnnualReturnInceptionDate	Jan. 02, 2003
INTECH U.S. Growth Fund | Class A, C, S, I, T Shares | Return Before Taxes | Class T
Risk/Return:	rr_RiskReturnAbstract
Column	rr_AverageAnnualReturnColumnName	Class T Shares
Label	rr_AverageAnnualReturnLabel	Return Before Taxes
1 Year	rr_AverageAnnualReturnYear01	15.53%
5 Years	rr_AverageAnnualReturnYear05	0.95%
Since Inception of Predecessor Fund	rr_AverageAnnualReturnSinceInception	6.38%
Inception Date	rr_AverageAnnualReturnInceptionDate	Jan. 02, 2003
INTECH U.S. Growth Fund | Class A, C, S, I, T Shares | Return After Taxes on Distributions | Class S
Risk/Return:	rr_RiskReturnAbstract
Column	rr_AverageAnnualReturnColumnName	Class S Shares
Label	rr_AverageAnnualReturnLabel	Return After Taxes on Distributions
1 Year	rr_AverageAnnualReturnYear01	15.08%
5 Years	rr_AverageAnnualReturnYear05	0.84%
Since Inception of Predecessor Fund	rr_AverageAnnualReturnSinceInception	5.89%
Inception Date	rr_AverageAnnualReturnInceptionDate	Jan. 02, 2003
INTECH U.S. Growth Fund | Class A, C, S, I, T Shares | Return After Taxes on Distributions and Sale of Fund Shares | Class S
Risk/Return:	rr_RiskReturnAbstract
Column	rr_AverageAnnualReturnColumnName	Class S Shares
Label	rr_AverageAnnualReturnLabel	Return After Taxes on Distributions and Sale of Fund Shares
1 Year	rr_AverageAnnualReturnYear01	10.12%
5 Years	rr_AverageAnnualReturnYear05	0.79%
Since Inception of Predecessor Fund	rr_AverageAnnualReturnSinceInception	5.41%
Inception Date	rr_AverageAnnualReturnInceptionDate	Jan. 02, 2003
INTECH U.S. Growth Fund | Class A, C, S, I, T Shares | Russell 1000® Growth Index (reflects no deduction for expenses, fees, or taxes)
Risk/Return:	rr_RiskReturnAbstract
Label	rr_AverageAnnualReturnLabel	Russell 1000® Growth Index
1 Year	rr_AverageAnnualReturnYear01	15.26%
5 Years	rr_AverageAnnualReturnYear05	3.12%
Since Inception of Predecessor Fund	rr_AverageAnnualReturnSinceInception	7.16%
Inception Date	rr_AverageAnnualReturnInceptionDate	Jan. 02, 2003

[1] Calculated assuming maximum permitted sales loads.

[2] The one year return is calculated to include the contingent deferred sales charge.

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Janus Real Return Fund | Class D Shares

FUND SUMMARY

Janus Real Return Fund

INVESTMENT OBJECTIVE

Janus Real Return Fund seeks real return consistent with preservation of capital.

FEES AND EXPENSES OF THE FUND

This table describes the fees and expenses that you may pay if you buy and hold Shares of the Fund.

ANNUAL FUND OPERATING EXPENSES
(expenses that you pay each year as a percentage of the value of your investment)

Annual Fund Operating Expenses		Janus Real Return Fund Class D Shares Class D
Operating Expenses Column [Text]		Class D
Management Fees		0.55%
Other Expenses	[1]	2.53%
Total Annual Fund Operating Expenses	[2]	3.08%
Fee Waiver	[2]	2.20%
Total Annual Fund Operating Expenses After Fee Waiver	[2]	0.88%

EXAMPLE:

The following Example is based on expenses without waivers. The Example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds.

The Example assumes that you invest $10,000 in the Fund for the time periods indicated, reinvest all dividends and distributions, and then redeem all of your Shares at the end of each period. The Example also assumes that your investment has a 5% return each year and that the Fund’s operating expenses without waivers or recoupments (if applicable) remain the same. Although your actual costs may be higher or lower, based on these assumptions your costs would be:

Expense Example (USD $)	Expense Example, By Year, Column [Text]	1 Year	3 Years	5 Years	10 Years
Janus Real Return Fund Class D Shares Class D	Class D Shares	311	951	1,616	3,392

Portfolio Turnover: 

The Fund pays transaction costs, such as commissions, when it buys and sells securities (or “turns over” its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when Fund shares are held in a taxable account. These costs, which are not reflected in annual fund operating expenses or in the Example, affect the Fund’s performance. During the most recent fiscal year, the Fund’s portfolio turnover rate was 112% of the average value of its portfolio.

PRINCIPAL INVESTMENT STRATEGIES

The Fund pursues its investment objective by primarily investing in U.S. Treasury securities, short-duration high-yield/high-risk debt, commodity-linked investments, and equity securities. The Fund’s investments in U.S. Treasury securities may also include Treasury Inflation-Protected Securities, also known as TIPS. As utilized by the Fund, each of these types of investments may be considered an “inflation-related investment,” which are those that may provide what is known as “real return,” or a rate of return above the rate of inflation over a full market cycle. Due to the nature of securities in which the Fund invests, it may have relatively high portfolio turnover compared to other funds.

The Fund may invest up to 90% of its net assets in short-duration high-yield/high-risk debt securities. The Fund’s investments in short-duration high-yield/high-risk securities include debt rated below investment grade, also known as “junk” bonds. Securities rated below investment grade may include their unrated equivalents or other high-yielding securities the portfolio managers believe offer attractive risk/return characteristics. The Fund may also invest in certain investment grade debt instruments, including corporate bonds, government bonds, municipal bonds, mortgage-backed securities, zero-coupon bonds, and agency securities. The Fund may invest in foreign debt securities.

To seek exposure to the commodities markets, the Fund may invest in commodity-linked investments such as commodity-related exchange-traded funds (“ETFs”), commodity index-linked swap agreements, commodity options and futures, and options on futures that provide exposure to the investment returns of the commodities markets. The Fund may also invest in other commodity-linked derivative instruments, such as commodity-linked notes (“structured notes”).

The Fund’s investments in equity securities may include common stock, preferred stock, and convertible securities, all of which may include exposure to foreign markets. The Fund may invest in companies of any market capitalization. The Fund’s equity investments may also include securities of real estate-related companies, including, but not limited to, real estate investment trusts (“REITs”) and similar REIT-like entities, such as foreign entities that have REIT characteristics.

The Fund may also invest in derivative instruments (by taking long and/or short positions) for various purposes, including hedging by shorting interest rate futures against long positions in TIPS, using inflation index swaps to hedge against unexpected changes in the rate of inflation, using interest rate swaps to hedge against changes in interest rates, using currency swaps to adjust its currency exposure, to increase or decrease the Fund’s exposure to a particular market, to manage or adjust the risk profile of the Fund related to an investment, and to earn income and enhance returns. The Fund’s exposure to derivatives will vary, is not limited to those derivatives listed, and could be significant at times.

The Fund may also use reverse repurchase agreements to generate income as part of its inflation-related strategies. Proceeds from reverse repurchase agreement transactions may be invested in other securities or instruments to attempt to increase the Fund’s investment return. The Fund may also invest in money market instruments, buy backs or dollar rolls, other securitized debt products, bank loans, various when-issued securities, exchange-traded notes, and other investment companies.

In addition to considering economic factors such as the rate of inflation and the effect of interest rates on the Fund’s investments, the portfolio managers apply a “bottom up” approach in choosing investments. This means that the portfolio managers look at securities one at a time to determine if a security is an attractive investment opportunity and if it is consistent with the Fund’s investment policies.

The Fund may lend portfolio securities on a short-term or long-term basis, in an amount equal to up to 1/3 of its total assets as determined at the time of the loan origination.

PRINCIPAL INVESTMENT RISKS

Although the Fund may be less volatile than funds that invest most of their assets in common stocks, the Fund’s returns and yields will vary, and you could lose money.

Fixed-Income Securities Risk. The Fund invests in a variety of fixed-income securities. Typically, the values of fixed-income securities change inversely with prevailing interest rates. Therefore, a fundamental risk of fixed-income securities is interest rate risk, which is the risk that the value of such securities will generally decline as prevailing interest rates rise, which may cause the Fund’s net asset value to likewise decrease. How specific fixed-income securities may react to changes in interest rates will depend on the specific characteristics of each security. Fixed-income securities are also subject to credit risk, prepayment risk, valuation risk, and liquidity risk. Credit risk is the risk that the credit strength of an issuer of a fixed-income security will weaken and/or that the issuer will be unable to make timely principal and interest payments and that the security may go into default. Prepayment risk is the risk that during periods of falling interest rates, certain fixed-income securities with higher interest rates, such as mortgage- and asset-backed securities, may be prepaid by their issuers thereby reducing the amount of interest payments. Valuation risk is the risk that one or more of the fixed-income securities in which the Fund invests are priced differently than the value realized upon such security’s sale. In times of market instability, valuation may be more difficult. Liquidity risk is the risk that fixed-income securities may be difficult or impossible to sell at the time that the portfolio managers would like or at the price the portfolio managers believe the security is currently worth.

High-Yield/High-Risk Bond Risk. The Fund may invest up to 90% of its net assets in higher-yielding/higher-risk bonds, also known as “junk” bonds. High-yield/high-risk bonds may be more sensitive than other types of bonds to economic changes, political changes, or adverse developments specific to the company that issued the bond, which may adversely affect their value.

Sovereign Debt Risk. The Fund may invest in U.S. and foreign government debt securities (“sovereign debt”). Investments in U.S. sovereign debt are considered low risk. However, investments in non-U.S. sovereign debt can involve a high degree of risk, including the risk that the governmental entity that controls the repayment of sovereign debt may not be willing or able to repay the principal and/or to pay the interest on its sovereign debt in a timely manner. A sovereign debtor’s willingness or ability to satisfy its debt obligation may be affected by various factors including, but not limited to, its cash flow situation, the extent of its foreign currency reserves, the availability of foreign exchange when a payment is due, and the relative size of its debt position in relation to its economy as a whole. In the event of default, there may be limited or no legal remedies for collecting sovereign debt and there may be no bankruptcy proceedings through which the Fund may collect all or part of the sovereign debt that a governmental entity has not repaid.

Foreign Exposure Risk. The Fund may have exposure to foreign markets as a result of its investments in foreign securities, including investments in emerging markets, which can be more volatile than the U.S. markets. As a result, its returns and net asset value may be affected to a large degree by fluctuations in currency exchange rates or political or economic conditions in a particular country. In some foreign markets, there may not be protection against failure by other parties to complete transactions. It may not be possible for the Fund to repatriate capital, dividends, interest, and other income from a particular country or governmental entity. In addition, a market swing in one or more countries or regions where the Fund has invested a significant amount of its assets may have a greater effect on the Fund’s performance than it would in a more geographically diversified portfolio. To the extent the Fund invests in foreign debt securities, such investments are sensitive to changes in interest rates. Additionally, investments in securities of foreign governments involve the risk that a foreign government may not be willing or able to pay interest or repay principal when due.

Real Estate Securities Risk. The Fund’s performance may be affected by the risks associated with investments in real estate-related companies. The value of real estate-related companies’ securities is sensitive to changes in real estate values and rental income, property taxes, interest rates, tax and regulatory requirements, supply and demand, and the management skill and creditworthiness of the company. Investments in REITs involve the same risks as other real estate investments. In addition, a REIT could fail to qualify for tax-free pass-through of its income under the Internal Revenue Code or fail to maintain its exemption from registration under the Investment Company Act of 1940, as amended, which could produce adverse economic consequences for the REIT and its investors, including the Fund.

Inflation-Related Investment Risk. Inflation index swaps, inflation-linked bonds (including Treasury Inflation-Protected Securities (“TIPS”)), and other inflation-linked securities are subject to inflation risk. A swap held long by the Fund can potentially lose value if the rate of inflation over the life of the swap is less than the fixed rate that the Fund agrees to pay at the initiation of the swap. Except for the Fund’s investments in TIPS, which are guaranteed as to principal by the U.S. Treasury, the inflation-adjusted principal value of inflation-linked bonds repaid at maturity may be less than the original principal. Because of their inflation-linked adjustment feature, inflation-linked bonds typically have lower yields than conventional fixed-rate securities. In the event of deflation, where prices decline over time, the principal and income of inflation-linked bonds will likely decline, resulting in losses to the Fund.

Commodity-Linked Investments Risk. The Fund may invest in various commodity-linked investments that provide exposure to the commodities markets. Such exposure may subject the Fund to greater volatility than investments in traditional securities. The value of a given commodity-linked derivative investment typically is based upon the price movements of a physical commodity (such as heating oil, livestock, or agricultural products), a commodity futures contract or commodity index, or some other readily measurable economic variable. The value of commodity-linked derivative instruments may therefore be affected by changes in overall market movements, volatility of the underlying benchmark, changes in interest rates, or other factors affecting a particular industry or commodity such as drought, floods, weather, livestock disease, embargoes, tariffs, and international economic, political, and regulatory developments.

Derivatives Risk. Derivatives can be highly volatile and involve risks in addition to the risks of the underlying referenced securities. Gains or losses from a derivative investment can be substantially greater than the derivative’s original cost, and can therefore involve leverage. Leverage may cause the Fund to be more volatile than if it had not used leverage. Derivatives can be complex instruments and may involve analysis that differs from that required for other investment types used by the Fund. If the value of a derivative does not correlate well with the particular market or other asset class to which the derivative is intended to provide exposure, the derivative may not produce the anticipated result. Derivatives can also reduce the opportunity for gain or result in losses by offsetting positive returns in other investments. Derivatives can be less liquid than other types of investments and entail the risk that the counterparty will default on its payment obligations. If the counterparty to a derivative transaction defaults, the Fund would risk the loss of the net amount of the payments that it contractually is entitled to receive. To the extent the Fund enters into short derivative positions, the Fund may be exposed to risks similar to those associated with short sales, including the risk that the Fund’s losses are theoretically unlimited.

Counterparty Risk. Certain derivative and “over-the-counter” instruments, such as swaps and forwards, are subject to the risk that the other party to a contract will not fulfill its contractual obligations.

Exchange-Traded Funds Risk. The Fund may invest in ETFs, which are typically open-end investment companies that are traded on a national securities exchange. ETFs typically incur fees, such as investment advisory fees and other operating expenses that are separate from those of the Fund, which will be indirectly paid by the Fund. As a result, the cost of investing in the Fund may be higher than the cost of investing directly in ETFs and may be higher than other mutual funds that invest directly in stocks and bonds. Further, the price movement of an ETF may fluctuate against the underlying securities or commodities it tracks and may result in a loss. Because the value of ETF shares depends on the demand in the market, the Fund may not be able to purchase or sell an ETF at the most optimal time, which could adversely affect the Fund’s performance.

The ETFs in which the Fund invests are subject to specific risks, depending on the investment strategy of the ETF. In turn, the Fund will be subject to substantially the same risks as those associated with direct exposure to the securities or commodities held by the ETF. Because the Fund may invest in a broad range of ETFs, such risks may include, but are not limited to, leverage risk, foreign exposure risk, and commodities risk.

Mortgage-Backed Securities Risk. Mortgage-backed securities are classified generally as either commercial mortgage-backed securities or residential mortgage-backed securities, each of which is subject to certain specific risks. Mortgage-backed securities tend to be more sensitive to changes in interest rates than other types of debt securities. Investments in mortgage-backed securities are subject to both extension risk, where borrowers extend the duration of their mortgages in times of rising interest rates, and prepayment risk, where borrowers pay off their mortgages sooner than expected in times of declining interest rates. These risks may reduce the Fund’s returns. In addition, investments in mortgage-backed securities, including those comprised of subprime mortgages, may be subject to a higher degree of credit risk, valuation risk, and liquidity risk than various other types of fixed-income securities.

Reverse Repurchase Agreement Risk. Reverse repurchase agreements involve leverage risk, counterparty risk, and the risk that the value of securities that the Fund is obligated to repurchase under the agreement may decline below the repurchase price. When the Fund invests reverse repurchase transaction proceeds, the Fund is at risk for any fluctuations in the value of securities in which the proceeds are invested. To the extent the Fund uses reverse repurchase agreements, the value of an investment in the Fund may be more volatile, and such transactions may increase the Fund’s overall investment exposure. Additionally, interest expenses related to reverse repurchase transactions could exceed the rate of return on debt obligations and other investments held by the Fund, thereby reducing returns to shareholders.

Nondiversification Risk. The Fund is classified as nondiversified under the Investment Company Act of 1940, as amended. This gives the Fund’s portfolio managers more flexibility to hold larger positions in a smaller number of securities. As a result, an increase or decrease in the value of a single security held by the Fund may have a greater impact on the Fund’s net asset value and total return.

Portfolio Turnover Risk. Increased portfolio turnover may result in higher costs, which may have a negative effect on the Fund’s performance. In addition, higher portfolio turnover may result in the acceleration of capital gains and the recognition of greater levels of short-term capital gains, which are taxed at ordinary federal income tax rates when distributed to shareholders.

Securities Lending Risk. The Fund may seek to earn additional income through lending its securities to certain qualified broker-dealers and institutions. There is the risk that when portfolio securities are lent, the securities may not be returned on a timely basis, and the Fund may experience delays and costs in recovering the security or gaining access to the collateral provided to the Fund to collateralize the loan. If the Fund is unable to recover a security on loan, the Fund may use the collateral to purchase replacement securities in the market. There is a risk that the value of the collateral could decrease below the cost of the replacement security by the time the replacement investment is made, resulting in a loss to the Fund.

An investment in the Fund is not a bank deposit and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency.

PERFORMANCE INFORMATION

The following information provides some indication of the risks of investing in the Fund by showing how the Fund’s performance has varied over time. The bar chart depicts the Fund’s performance during the period indicated. The table compares the Fund’s average annual returns for the periods indicated to broad-based securities market indices. The indices are not actively managed and are not available for direct investment. All figures assume reinvestment of dividends and distributions. For certain periods, the Fund’s performance reflects the effect of expense waivers. Without the effect of these expense waivers, the performance shown would have been lower.

The Fund’s past performance (before and after taxes) does not necessarily indicate how it will perform in the future. Updated performance information is available at janus.com/allfunds or by calling 1-800-525-3713.

Annual Total Returns for Class D Shares (calendar year-end)

Best Quarter:  First Quarter 2012  5.63%          Worst Quarter:  Second Quarter 2012  −3.82%

The Fund’s year-to-date return as of the calendar quarter ended September 30, 2013 was 1.16%.

Average Annual Total Returns (periods ended 12/31/12)

Average Annual Total Returns Janus Real Return Fund Class D Shares	Column	Label		1 Year	Since Inception	Inception Date
Class D Return Before Taxes	Class D Shares	Return Before Taxes		4.87%	(0.24%)	May 13, 2011
Class D Return After Taxes on Distributions	Class D Shares	Return After Taxes on Distributions		4.69%	(0.48%)	May 13, 2011
Class D Return After Taxes on Distributions and Sale of Fund Shares	Class D Shares	Return After Taxes on Distributions and Sale of Fund Shares	[1]	3.27%	(0.29%)	May 13, 2011
Barclays U.S. 1-5 Year TIPS Index (reflects no deduction for expenses, fees, or taxes)		Barclays U.S. 1-5 Year TIPS Index		2.66%	2.44%	May 13, 2011
Consumer Price Index +200 (reflects no deduction for expenses, fees, or taxes)		Consumer Price Index +200		4.02%	2.99%	May 13, 2011
Barclays U.S. TIPS Index (reflects no deduction for expenses, fees, or taxes)		Barclays U.S. TIPS Index		6.98%	9.76%	May 13, 2011
Consumer Price Index +400 (reflects no deduction for expenses, fees, or taxes)		Consumer Price Index +400		6.02%	4.97%	May 13, 2011

Effective October 15, 2012, the Fund’s primary benchmark index changed from the Barclays U.S. TIPS Index to the Barclays U.S. 1-5 Year TIPS Index. Additionally, the Fund changed its secondary benchmark index from the Consumer Price Index +400 to the Consumer Price Index +200. Janus Capital believes that the foregoing benchmark index changes provide a more appropriate representation of the Fund’s investment strategy.

After-tax returns are calculated using the historically highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes. Actual after-tax returns depend on your individual tax situation and may differ from those shown in the preceding table. The after-tax return information shown above does not apply to Fund shares held through a tax-deferred account, such as a 401(k) plan or an IRA.

[1] Other Expenses are based on the estimated expenses that the Fund expects to incur.

[2] Janus Capital has contractually agreed to waive its investment advisory fee and/or reimburse Fund expenses to the extent that the Fund’s total annual fund operating expenses (excluding administrative services fees payable pursuant to the Transfer Agency Agreement, brokerage commissions, interest, dividends, taxes, acquired fund fees and expenses, and extraordinary expenses) exceed 0.76% until at least November 1, 2014. The contractual waiver may be terminated or modified prior to this date only at the discretion of the Board of Trustees. For a period of three years subsequent to the Fund’s commencement of operations (May 13, 2011) or until the Fund’s assets exceed the first breakpoint in the investment advisory fee schedule that was effective at commencement of operations, whichever occurs first, Janus Capital may recover from the Fund fees and expenses previously waived or reimbursed, which could then be considered a deferral, if the Fund’s expense ratio, including recovered expenses, falls below the expense limit.

[1] If the Fund incurs a loss, which generates a tax benefit, the Return After Taxes on Distributions and Sale of Fund Shares may exceed the Fund’s other return figures.

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Janus Global Allocation Fund - Growth | Class A, C, S, I, T Shares

FUND SUMMARY

Janus Global Allocation Fund – Growth
(formerly named Janus Growth Allocation Fund)

INVESTMENT OBJECTIVE

Janus Global Allocation Fund – Growth seeks total return through a primary emphasis on growth of capital with a secondary emphasis on income.

FEES AND EXPENSES OF THE FUND

This table describes the fees and expenses that you may pay if you buy and hold Shares of the Fund. Each share class has different expenses, but represents an investment in the same Fund.

For Class A Shares, you may qualify for sales charge discounts if you and your family invest, or agree to invest in the future, at least $50,000 in the Fund or in other Janus mutual funds. More information about these and other discounts, as well as eligibility requirements for each share class, is available from your financial professional and in the “Purchases” section on page 52 of the Fund’s Prospectus and in the “Purchases” section on page 57 of the Fund’s Statement of Additional Information.

SHAREHOLDER FEES
(fees paid directly from your investment)

Shareholder Fees Janus Global Allocation Fund - Growth Class A, C, S, I, T Shares	Class A	Class C	Class S	Class I	Class T
Shareholder Fees Column [Text]	Class A	Class C	Class S	Class I	Class T
Maximum Sales Charge (load) Imposed on Purchases (as a percentage of offering price)	5.75%	none	none	none	none
Maximum Deferred Sales Charge (load) (as a percentage of the lower of original purchase price or redemption proceeds)	none	1.00%	none	none	none

ANNUAL FUND OPERATING EXPENSES
(expenses that you pay each year as a percentage of the value of your investment)

Annual Fund Operating Expenses Janus Global Allocation Fund - Growth Class A, C, S, I, T Shares	Class A	Class C	Class S	Class I	Class T
Operating Expenses Column [Text]	Class A	Class C	Class S	Class I	Class T
Management Fees	0.05%	0.05%	0.05%	0.05%	0.05%
Distribution/Service (12b-1) Fees	0.25%	1.00%	0.25%	none	none
Other Expenses	0.11%	0.16%	0.31%	0.15%	0.31%
Acquired Fund Fees and Expenses	0.71%	0.71%	0.71%	0.71%	0.71%
Total Annual Fund Operating Expenses	1.12%	1.92%	1.32%	0.91%	1.07%

EXAMPLE:

The Example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds.

The Example assumes that you invest $10,000 in the Fund for the time periods indicated and reinvest all dividends and distributions. The Example also assumes that your investment has a 5% return each year and that the Fund’s operating expenses (including the operating expenses of the underlying funds) remain the same. Although your actual costs may be higher or lower, based on these assumptions your costs would be:

If Shares are redeemed:

Expense Example Janus Global Allocation Fund - Growth Class A, C, S, I, T Shares (USD $)	Expense Example, By Year, Column [Text]	1 Year	3 Years	5 Years	10 Years
Class A	Class A Shares	683	911	1,156	1,860
Class C	Class C Shares	295	603	1,037	2,243
Class S	Class S Shares	134	418	723	1,590
Class I	Class I Shares	93	290	504	1,120
Class T	Class T Shares	109	340	590	1,306

If Shares are not redeemed:

Expense Example, No Redemption Janus Global Allocation Fund - Growth Class A, C, S, I, T Shares (USD $)	Expense Example, No Redemption, By Year, Column [Text]	1 Year	3 Years	5 Years	10 Years
Class A	Class A Shares	683	911	1,156	1,860
Class C	Class C Shares	195	603	1,037	2,243
Class S	Class S Shares	134	418	723	1,590
Class I	Class I Shares	93	290	504	1,120
Class T	Class T Shares	109	340	590	1,306

Portfolio Turnover: 

The Fund pays transaction costs, such as commissions, when it buys and sells securities (or “turns over” its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when Fund shares are held in a taxable account. These costs, which are not reflected in annual fund operating expenses or in the Example, affect the Fund’s performance. During the most recent fiscal year, the Fund’s portfolio turnover rate was 45% of the average value of its portfolio.

PRINCIPAL INVESTMENT STRATEGIES

The Fund seeks to achieve its investment objective by investing in other Janus mutual funds (“underlying funds”) that represent a variety of asset classes and investment styles and provide exposure to issuers that are economically tied to countries throughout the world. Through its investments in underlying funds, the Fund invests in issuers from several different countries and may, under unusual circumstances, be invested in a single country. As a result, the Fund normally will have approximately 40% of its net assets allocated to non-U.S. investments. The Fund may also have significant exposure to emerging markets.

The Fund pursues this objective by investing in a diversified portfolio of underlying funds, resulting in an allocation of the Fund’s investments that normally provides exposure of approximately 75% to equity investments, 15% to fixed-income securities and money market instruments, and 10% to alternative investments. The target allocation and the allocation of the Fund’s assets among underlying funds are based on quantitative and qualitative analysis. Because it invests in other funds, the Fund is considered a “fund of funds.”

The Fund’s asset allocation is intended to diversify investments throughout the world among equity investments, fixed-income securities, cash equivalents, and alternative investments. The portfolio manager determines the overall composition of the Fund, oversees the investment process, and is responsible for the day-to-day management of the Fund. The portfolio manager continually monitors asset class allocations and periodically rebalances the Fund’s investments in the underlying funds. The portfolio manager also regularly reviews the allocation of Fund assets in the underlying funds and may modify the underlying funds’ weightings or substitute other underlying funds to emphasize and mitigate risk exposures that may arise as a result of the implementation of the allocations. An independent asset allocation service provides evaluations of asset allocations that the portfolio manager may use in implementing the allocations among the underlying funds.

Additionally, the portfolio manager consults with a committee (the “Janus Global Allocation Committee”) to regularly review the broad market, macroeconomic conditions and other global financial factors that may impact the Fund’s allocation of assets among the underlying funds and asset classes. The Janus Global Allocation Committee is comprised of investment professionals of Janus Capital and may also include investment professionals of Janus Capital’s affiliated investment advisers. The portfolio manager and Janus Global Allocation Committee normally meet on a quarterly basis. The portfolio manager may change the Fund’s asset class allocations, the underlying funds, an underlying fund’s asset category, or weightings among asset classes or underlying funds without prior shareholder notice.

The Fund will normally allocate approximately 75% of its investments to underlying funds that provide varying exposure to common stocks of large U.S.-based companies, small- to mid-capitalization companies, and international companies (including those with exposure to emerging markets), approximately 15% of its investments to underlying bond funds and money market instruments, and approximately 10% of its investments to underlying funds that seek returns uncorrelated with the returns of stocks and bonds by providing exposure to alternative investments and alternative investment strategies. Refer to Appendix A in this Prospectus for a brief description of the investment strategies of each of the currently available underlying funds.

When market conditions dictate a more defensive strategy, the Fund or an underlying fund may temporarily hold cash or invest its assets in temporary investments. In that case, the Fund may take positions that are inconsistent with its investment objective. As a result, the Fund may not achieve its investment objective.

PRINCIPAL INVESTMENT RISKS

The biggest risk is that the Fund’s returns will vary, and you could lose money. The Fund is designed for long-term investors seeking growth of capital and, to a lesser extent, income. Investments in a portfolio with common stock and alternative investment exposure tend to be more volatile than many other investment choices.

Main Risks Associated with the Fund
Allocation Risk. The Fund’s ability to achieve its investment objective depends largely upon the portfolio manager’s allocation of assets among the underlying funds and other securities, using the optimization process (a process that utilizes quantitative analysis of a number of factors, such as historical risk, performance, fund classifications, and the relationship among underlying funds) and the judgment of the portfolio manager. You could lose money on your investment in the Fund as a result of these allocations. The Fund will typically invest in a number of different underlying funds; however, to the extent that the Fund invests a significant portion of its assets in a single underlying fund, it will be more sensitive to the risks associated with that fund and any investments in which that fund focuses.

Affiliated Fund Risk. Janus Capital has the authority to select and substitute underlying affiliated mutual funds. The fees paid to Janus Capital by some Janus mutual funds are generally higher than the fees paid to Janus Capital by the Fund or by other funds and share classes available for investment by the Fund. These conditions may create a conflict of interest when selecting underlying affiliated mutual funds and share classes for investment. Janus Capital, however, is a fiduciary to the Fund and its shareholders and is legally obligated to act in their best interest when selecting underlying affiliated mutual funds.

Main Risks Associated with the Underlying Funds and Securities
The biggest risk is that the underlying funds’ returns will vary, and you could lose money.

Market Risk. Approximately 75% of the Fund’s assets are allocated to equity investments through investments in underlying funds. The value of an underlying fund’s portfolio may decrease if the value of an individual company or security, or multiple companies or securities, in the portfolio decreases or if a portfolio manager’s belief about a company’s intrinsic worth is incorrect. Further, regardless of how well individual companies or securities perform, the value of an underlying fund’s portfolio could also decrease if there are deteriorating economic or market conditions. It is important to understand that the value of your investment may fall, sometimes sharply, in response to changes in the market, and you could lose money.

Foreign Exposure Risk. Certain underlying funds may have significant exposure to foreign markets as a result of their investments in foreign securities, including investments in emerging markets, which can be more volatile than the U.S. markets. As a result, an underlying fund’s returns and net asset value may be affected to a large degree by fluctuations in currency exchange rates or political or economic conditions in a particular country. A market swing in one or more countries or regions where an underlying fund has invested a significant amount of its assets may have a greater effect on an underlying fund’s performance than it would in a more geographically diversified portfolio. An underlying fund’s investments in emerging market countries may involve risks greater than, or in addition to, the risks of investing in more developed countries.

Emerging Markets Risk. The risks of foreign investing mentioned above are heightened when investing in emerging markets. Emerging markets securities involve a number of additional risks, which may result from less government supervision and regulation of business and industry practices (including the potential lack of strict finance and accounting controls and standards), stock exchanges, brokers, and listed companies, making these investments potentially more volatile in price and less liquid than investments in developed securities markets, resulting in greater risk to investors. In addition, an underlying fund’s investments may be denominated in foreign currencies and therefore, changes in the value of a country’s currency compared to the U.S. dollar may affect the value of an underlying fund’s investments. To the extent that an underlying fund invests a significant portion of its assets in the securities of issuers in or companies of a single country or region, it is more likely to be impacted by events or conditions affecting that country or region, which could have a negative impact on the Fund’s performance. Some of the risks of investing directly in foreign and emerging market securities may be reduced when an underlying fund invests indirectly in foreign securities through various other investment vehicles including derivatives, which also involve other risks.

Sovereign Debt Risk. An underlying fund may invest in U.S. and foreign government debt securities (“sovereign debt”). Investments in U.S. sovereign debt are considered low risk. However, investments in non-U.S. sovereign debt can involve a high degree of risk, including the risk that the governmental entity that controls the repayment of sovereign debt may not be willing or able to repay the principal and/or to pay the interest on its sovereign debt in a timely manner. A sovereign debtor’s willingness or ability to satisfy its debt obligation may be affected by various factors including, but not limited to, its cash flow situation, the extent of its foreign currency reserves, the availability of foreign exchange when a payment is due, and the relative size of its debt position in relation to its economy as a whole. In the event of default, there may be limited or no legal remedies for collecting sovereign debt and there may be no bankruptcy proceedings through which the underlying fund may collect all or part of the sovereign debt that a governmental entity has not repaid.

Fixed-Income Securities Risk. Approximately 15% of the Fund’s assets are allocated to fixed-income securities through investments in underlying funds. Typically, the values of fixed-income securities change inversely with prevailing interest rates. Therefore, a fundamental risk of fixed-income securities is interest rate risk, which is the risk that the value of such securities will generally decline as prevailing interest rates rise, which may cause an underlying fund’s net asset value to likewise decrease. How specific fixed-income securities may react to changes in interest rates will depend on the specific characteristics of each security. Fixed-income securities are also subject to credit risk, prepayment risk, valuation risk, and liquidity risk. Credit risk is the risk that the credit strength of an issuer of a fixed-income security will weaken and/or that the issuer will be unable to make timely principal and interest payments and that the security may go into default. Prepayment risk is the risk that during periods of falling interest rates, certain fixed-income securities with higher interest rates, such as mortgage- and asset-backed securities, may be prepaid by their issuers thereby reducing the amount of interest payments. Valuation risk is the risk that one or more of the fixed-income securities in which an underlying fund invests are priced differently than the value realized upon such security’s sale. In times of market instability, valuation may be more difficult. Liquidity risk is the risk that fixed-income securities may be difficult or impossible to sell at the time that an underlying fund’s portfolio manager would like or at the price the portfolio manager believes the security is currently worth.

Mortgage-Backed Securities Risk. Mortgage-backed securities are classified generally as either commercial mortgage-backed securities or residential mortgage-backed securities, each of which is subject to certain specific risks. Mortgage-backed securities tend to be more sensitive to changes in interest rates than other types of debt securities. Investments in mortgage-backed securities are subject to both extension risk, where borrowers extend the duration of their mortgages in times of rising interest rates, and prepayment risk, where borrowers pay off their mortgages sooner than expected in times of declining interest rates. These risks may reduce the Fund’s returns. In addition, investments in mortgage-backed securities, including those comprised of subprime mortgages, may be subject to a higher degree of credit risk, valuation risk, and liquidity risk than various other types of fixed-income securities.

Alternative Investments Allocation Risk. Approximately 10% of the Fund’s assets are allocated to alternative investments through investments in underlying funds that invest in alternative investment strategies. In connection with the Fund’s allocation to alternative investments, the Fund may invest in a Janus underlying fund, Janus Diversified Alternatives Fund, which seeks returns uncorrelated with the returns generated by investments in stocks and bonds. In addition, as part of its alternative investments allocation, the Fund may invest in Janus Global Real Estate Fund. Janus Diversified Alternatives Fund’s ability to achieve its investment objective depends largely upon the successful evaluation of the risk, potential returns, and correlation properties with respect to its investments. There is a risk that the returns provided by alternative investments may be subject to high volatility and that an underlying fund’s portfolio manager’s beliefs about the expected returns, risk and correlation properties of one or more of an underlying fund’s investments may be incorrect. There is also a risk that an underlying fund’s investments will correlate with the performance of stocks and bonds to a greater degree than anticipated. Janus Capital does not have prior experience managing the investment strategy of Janus Diversified Alternatives Fund, and there is no guarantee that the investment techniques and analysis used by the underlying fund’s portfolio managers will produce the desired results. All of these factors may negatively affect your investment in the Fund and you could lose money. Investment in the underlying funds also involves derivatives, counterparty, leverage, real estate-related, and commodity-linked investment risks.

Counterparty Risk. Certain derivative and “over-the-counter” instruments, such as swaps and forwards, are subject to the risk that the other party to a contract will not fulfill its contractual obligations.

Commodity-Linked Investments Risk. Certain underlying funds may invest in derivatives that have exposure to the commodities markets. Such exposure may subject an underlying fund to greater volatility than investments in traditional securities. The value of a commodity-linked derivative investment typically is based upon the price movements of a physical commodity (such as heating oil, livestock, or agricultural products), a commodity futures contract or commodity index, or some other readily measurable economic variable. The value of commodity-linked derivative instruments may therefore be affected by changes in overall market movements, volatility of the underlying benchmark, changes in interest rates, or other factors affecting a particular industry or commodity such as drought, floods, weather, livestock disease, embargoes, tariffs, and international economic, political, and regulatory developments.

Derivatives Risk. Certain underlying funds may invest in derivatives. Derivatives can be highly volatile and involve risks in addition to the risks of the underlying referenced securities. Gains or losses from a derivative investment can be substantially greater than the derivative’s original cost, and can therefore involve leverage. Leverage may cause an underlying fund to be more volatile than if it had not used leverage. Derivatives can be less liquid than other types of investments and entail the risk that the counterparty will default on its payment obligations.

Exchange-Traded Funds Risk. Certain underlying funds may purchase shares of exchange-traded funds (“ETFs”) to gain exposure to a particular portion of the market. ETFs are pooled investment vehicles, which may be managed or unmanaged, that generally seek to track the performance of a specific index. ETFs are traded on an exchange at market prices that may vary from the net asset value of their underlying investments. When an underlying fund invests in an ETF, in addition to directly bearing the expenses associated with its own operations, it will bear a pro rata portion of the ETF’s expenses. ETFs have certain inherent risks generally associated with investments in a portfolio of securities in which the ETF is invested, including the risk that the general level of stock prices may decline, thereby adversely affecting the value of each unit of the ETF. ETFs also involve the risk that an active trading market for an ETF’s shares may not develop or be maintained.

Exchange-Traded Notes Risk. Certain underlying funds may invest in exchange-traded notes (“ETNs”), which are debt securities whose returns are linked to a particular index. ETNs are typically linked to the performance of a commodities index that reflects the potential return on unleveraged investments in futures contracts of physical commodities, plus a specified rate of interest that could be earned on cash collateral. ETNs are subject to credit risk and counterparty risk. The value of an ETN may vary and may be influenced by time to maturity, level of supply and demand for the ETN, volatility and lack of liquidity in underlying commodities markets, changes in the applicable interest rates, changes in the issuer’s credit rating, and economic, legal, political, or geographic events that affect the referenced commodity. When an underlying fund invests in ETNs it will bear its proportionate share of any fees and expenses borne by the ETN. There may be restrictions on an underlying fund’s right to redeem its investment in an ETN, which is meant to be held until maturity. An underlying fund’s decision to sell its ETN holdings may be limited by the availability of a secondary market.

An investment in the Fund is not a bank deposit and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency.

PERFORMANCE INFORMATION

The following information provides some indication of the risks of investing in the Fund by showing how the Fund’s performance has varied over time. Class T Shares (formerly named Class J Shares, the initial share class) of the Fund commenced operations with the Fund’s inception. Class A Shares, Class C Shares, Class S Shares, and Class I Shares of the Fund commenced operations on July 6, 2009.

• The performance shown for Class T Shares is calculated using the fees and expenses of Class T Shares in effect during the periods shown, net of any applicable fee and expense limitations or waivers.
• The performance shown for Class A Shares, Class C Shares, and Class S Shares for periods prior to July 6, 2009, reflects the performance of the Fund’s former Class J Shares, calculated using the fees and expenses of each respective share class, without the effect of any fee and expense limitations or waivers.
• The performance shown for Class I Shares for periods prior to July 6, 2009, reflects the performance of the Fund’s former Class J Shares, calculated using the fees and expenses of Class J Shares, net of any applicable fee and expense limitations or waivers.

If Class A Shares, Class C Shares, Class S Shares, and Class I Shares of the Fund had been available during periods prior to July 6, 2009, the performance shown for each respective share class may have been different. The performance shown for periods following the Fund’s commencement of Class A Shares, Class C Shares, Class S Shares, and Class I Shares reflects the fees and expenses of each respective share class, net of any applicable fee and expense limitations or waivers.

The bar chart depicts the change in performance from year to year during the periods indicated. Performance information for each underlying fund is available in its prospectus and/or the most recent annual or semiannual report. The bar chart figures do not include any applicable sales charges that an investor may pay when they buy or sell Class A Shares or Class C Shares of the Fund. If sales charges were included, the returns would be lower. The table compares the Fund’s average annual returns for the periods indicated to broad-based securities market indices. The indices are not actively managed and are not available for direct investment. All figures assume reinvestment of dividends and distributions. For certain periods, the Fund’s performance reflects the effect of expense waivers. Without the effect of these expense waivers, the performance shown would have been lower.

The Fund’s past performance (before and after taxes) does not necessarily indicate how it will perform in the future. Updated performance information is available at janus.com/advisor/mutual-funds or by calling 1-877-335-2687.

Annual Total Returns for Class T Shares (calendar year-end)

Best Quarter:  Second Quarter 2009  18.37%          Worst Quarter:  Fourth Quarter 2008  −18.05%

The Fund’s year-to-date return as of the calendar quarter ended September 30, 2013 was 12.39%.

Average Annual Total Returns (periods ended 12/31/12)

Average Annual Total Returns Janus Global Allocation Fund - Growth Class A, C, S, I, T Shares	Column	Label		1 Year	5 Years	Since Inception	Inception Date
Class T Return Before Taxes	Class T Shares	Return Before Taxes		14.79%	1.47%	5.71%	Dec. 30, 2005
Class T Return After Taxes on Distributions	Class T Shares	Return After Taxes on Distributions		14.29%	0.98%	5.12%	Dec. 30, 2005
Class T Return After Taxes on Distributions and Sale of Fund Shares	Class T Shares	Return After Taxes on Distributions and Sale of Fund Shares	[1]	9.91%	1.02%	4.68%	Dec. 30, 2005
Class A Return Before Taxes	Class A Shares	Return Before Taxes	[2]	8.09%	0.16%	4.68%	Dec. 30, 2005
Class C Return Before Taxes	Class C Shares	Return Before Taxes	[3]	12.53%	0.57%	4.77%	Dec. 30, 2005
Class S Return Before Taxes	Class S Shares	Return Before Taxes		14.54%	1.15%	5.34%	Dec. 30, 2005
Class I Return Before Taxes	Class I Shares	Return Before Taxes		15.05%	1.47%	5.71%	Dec. 30, 2005
Morgan Stanley Capital International All Country World Index℠ (net of foreign withholding taxes) (reflects no deduction for expenses, fees, or taxes, except foreign withholding taxes)		Morgan Stanley Capital International All Country World IndexSM (net of foreign withholding taxes)		16.13%	(1.16%)	3.52%	Dec. 30, 2005
Global Growth Allocation Index (reflects no deduction for expenses, fees, or taxes, except any applicable foreign withholding taxes)		Global Growth Allocation Index		13.80%	0.43%	4.30%	Dec. 30, 2005
S&P 500® Index (reflects no deduction for expenses, fees, or taxes)		S&P 500® Index		16.00%	1.66%	4.12%	Dec. 30, 2005
Growth Allocation Index (reflects no deduction for expenses, fees, or taxes, except any applicable foreign withholding taxes)		Growth Allocation Index		14.29%	1.76%	4.81%	Dec. 30, 2005

Effective February 15, 2013, the Fund’s primary benchmark index changed from the S&P 500^® Index to the Morgan Stanley Capital International (“MSCI”) All Country World Index^SM to reflect the global investment strategies of the Fund. Additionally, the Fund changed the name of its secondary benchmark index from Growth Allocation Index to Global Growth Allocation Index and its composition from an internally-calculated, hypothetical combination of unmanaged indices that combines total returns from the Dow Jones Wilshire 5000 Index (50%), the MSCI EAFE^® Index (25%), the Barclays U.S. Aggregate Bond Index (20%), and the MSCI Emerging Markets Free Index^SM (5%) to an internally-calculated, hypothetical combination of unmanaged indices that combines total returns from the MSCI All Country World Index^SM (80%) and the Barclays Global Aggregate Bond Index (20%). The MSCI All Country World Index^SM is an unmanaged, free float-adjusted market capitalization weighted index that is designed to measure the equity market performance of global developed and emerging markets. Janus Capital believes that the foregoing benchmark index changes provide a more appropriate representation of the Fund’s revised investment strategy that includes an increased focus on global investments, including emerging markets.

After-tax returns are calculated using distributions for the Fund’s Class T Shares (formerly named Class J Shares, the initial share class). After-tax returns are calculated using the historically highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes. Actual after-tax returns depend on your individual tax situation and may differ from those shown in the preceding table. The after-tax return information shown above does not apply to Fund shares held through a tax-deferred account, such as a 401(k) plan or an IRA.

After-tax returns are only shown for Class T Shares of the Fund. After-tax returns for the other classes of Shares will vary from those shown for Class T Shares due to varying sales charges (as applicable), fees, and expenses among the classes.

[1] If the Fund incurs a loss, which generates a tax benefit, the Return After Taxes on Distributions and Sale of Fund Shares may exceed the Fund’s other return figures.

[2] Calculated assuming maximum permitted sales loads.

[3] The one year return is calculated to include the contingent deferred sales charge.

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Janus Global Allocation Fund - Growth | Class D Shares

FUND SUMMARY

Janus Global Allocation Fund – Growth
(formerly named Janus Growth Allocation Fund)

INVESTMENT OBJECTIVE

Janus Global Allocation Fund – Growth seeks total return through a primary emphasis on growth of capital with a secondary emphasis on income.

FEES AND EXPENSES OF THE FUND

This table describes the fees and expenses that you may pay if you buy and hold Shares of the Fund.

ANNUAL FUND OPERATING EXPENSES
(expenses that you pay each year as a percentage of the value of your investment)

Annual Fund Operating Expenses	Janus Global Allocation Fund - Growth Class D Shares Class D
Operating Expenses Column [Text]	Class D
Management Fees	0.05%
Other Expenses	0.23%
Acquired Fund Fees and Expenses	0.71%
Total Annual Fund Operating Expenses	0.99%

EXAMPLE:

The Example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds.

The Example assumes that you invest $10,000 in the Fund for the time periods indicated, reinvest all dividends and distributions, and then redeem all of your Shares at the end of each period. The Example also assumes that your investment has a 5% return each year and that the Fund’s operating expenses (including the operating expenses of the underlying funds) remain the same. Although your actual costs may be higher or lower, based on these assumptions your costs would be:

Expense Example (USD $)	Expense Example, By Year, Column [Text]	1 Year	3 Years	5 Years	10 Years
Janus Global Allocation Fund - Growth Class D Shares Class D	Class D Shares	101	315	547	1,213

Portfolio Turnover: 

The Fund pays transaction costs, such as commissions, when it buys and sells securities (or “turns over” its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when Fund shares are held in a taxable account. These costs, which are not reflected in annual fund operating expenses or in the Example, affect the Fund’s performance. During the most recent fiscal year, the Fund’s portfolio turnover rate was 45% of the average value of its portfolio.

PRINCIPAL INVESTMENT STRATEGIES

The Fund seeks to achieve its investment objective by investing in other Janus mutual funds (“underlying funds”) that represent a variety of asset classes and investment styles and provide exposure to issuers that are economically tied to countries throughout the world. Through its investments in underlying funds, the Fund invests in issuers from several different countries and may, under unusual circumstances, be invested in a single country. As a result, the Fund normally will have approximately 40% of its net assets allocated to non-U.S. investments. The Fund may also have significant exposure to emerging markets.

The Fund pursues this objective by investing in a diversified portfolio of underlying funds, resulting in an allocation of the Fund’s investments that normally provides exposure of approximately 75% to equity investments, 15% to fixed-income securities and money market instruments, and 10% to alternative investments. The target allocation and the allocation of the Fund’s assets among underlying funds are based on quantitative and qualitative analysis. Because it invests in other funds, the Fund is considered a “fund of funds.”

The Fund’s asset allocation is intended to diversify investments throughout the world among equity investments, fixed-income securities, cash equivalents, and alternative investments. The portfolio manager determines the overall composition of the Fund, oversees the investment process, and is responsible for the day-to-day management of the Fund. The portfolio manager continually monitors asset class allocations and periodically rebalances the Fund’s investments in the underlying funds. The portfolio manager also regularly reviews the allocation of Fund assets in the underlying funds and may modify the underlying funds’ weightings or substitute other underlying funds to emphasize and mitigate risk exposures that may arise as a result of the implementation of the allocations. An independent asset allocation service provides evaluations of asset allocations that the portfolio manager may use in implementing the allocations among the underlying funds.

Additionally, the portfolio manager consults with a committee (the “Janus Global Allocation Committee”) to regularly review the broad market, macroeconomic conditions and other global financial factors that may impact the Fund’s allocation of assets among the underlying funds and asset classes. The Janus Global Allocation Committee is comprised of investment professionals of Janus Capital and may also include investment professionals of Janus Capital’s affiliated investment advisers. The portfolio manager and Janus Global Allocation Committee normally meet on a quarterly basis. The portfolio manager may change the Fund’s asset class allocations, the underlying funds, an underlying fund’s asset category, or weightings among asset classes or underlying funds without prior shareholder notice.

The Fund will normally allocate approximately 75% of its investments to underlying funds that provide varying exposure to common stocks of large U.S.-based companies, small- to mid-capitalization companies, and international companies (including those with exposure to emerging markets), approximately 15% of its investments to underlying bond funds and money market instruments, and approximately 10% of its investments to underlying funds that seek returns uncorrelated with the returns of stocks and bonds by providing exposure to alternative investments and alternative investment strategies. Refer to Appendix A in this Prospectus for a brief description of the investment strategies of each of the currently available underlying funds.

When market conditions dictate a more defensive strategy, the Fund or an underlying fund may temporarily hold cash or invest its assets in temporary investments. In that case, the Fund may take positions that are inconsistent with its investment objective. As a result, the Fund may not achieve its investment objective.

PRINCIPAL INVESTMENT RISKS

The biggest risk is that the Fund’s returns will vary, and you could lose money. The Fund is designed for long-term investors seeking growth of capital and, to a lesser extent, income. Investments in a portfolio with common stock and alternative investment exposure tend to be more volatile than many other investment choices.

Main Risks Associated with the Fund
Allocation Risk. The Fund’s ability to achieve its investment objective depends largely upon the portfolio manager’s allocation of assets among the underlying funds and other securities, using the optimization process (a process that utilizes quantitative analysis of a number of factors, such as historical risk, performance, fund classifications, and the relationship among underlying funds) and the judgment of the portfolio manager. You could lose money on your investment in the Fund as a result of these allocations. The Fund will typically invest in a number of different underlying funds; however, to the extent that the Fund invests a significant portion of its assets in a single underlying fund, it will be more sensitive to the risks associated with that fund and any investments in which that fund focuses.

Affiliated Fund Risk. Janus Capital has the authority to select and substitute underlying affiliated mutual funds. The fees paid to Janus Capital by some Janus mutual funds are generally higher than the fees paid to Janus Capital by the Fund or by other funds and share classes available for investment by the Fund. These conditions may create a conflict of interest when selecting underlying affiliated mutual funds and share classes for investment. Janus Capital, however, is a fiduciary to the Fund and its shareholders and is legally obligated to act in their best interest when selecting underlying affiliated mutual funds.

Main Risks Associated with the Underlying Funds and Securities
The biggest risk is that the underlying funds’ returns will vary, and you could lose money.

Market Risk. Approximately 75% of the Fund’s assets are allocated to equity investments through investments in underlying funds. The value of an underlying fund’s portfolio may decrease if the value of an individual company or security, or multiple companies or securities, in the portfolio decreases or if a portfolio manager’s belief about a company’s intrinsic worth is incorrect. Further, regardless of how well individual companies or securities perform, the value of an underlying fund’s portfolio could also decrease if there are deteriorating economic or market conditions. It is important to understand that the value of your investment may fall, sometimes sharply, in response to changes in the market, and you could lose money.

Foreign Exposure Risk. Certain underlying funds may have significant exposure to foreign markets as a result of their investments in foreign securities, including investments in emerging markets, which can be more volatile than the U.S. markets. As a result, an underlying fund’s returns and net asset value may be affected to a large degree by fluctuations in currency exchange rates or political or economic conditions in a particular country. A market swing in one or more countries or regions where an underlying fund has invested a significant amount of its assets may have a greater effect on an underlying fund’s performance than it would in a more geographically diversified portfolio. An underlying fund’s investments in emerging market countries may involve risks greater than, or in addition to, the risks of investing in more developed countries.

Emerging Markets Risk. The risks of foreign investing mentioned above are heightened when investing in emerging markets. Emerging markets securities involve a number of additional risks, which may result from less government supervision and regulation of business and industry practices (including the potential lack of strict finance and accounting controls and standards), stock exchanges, brokers, and listed companies, making these investments potentially more volatile in price and less liquid than investments in developed securities markets, resulting in greater risk to investors. In addition, an underlying fund’s investments may be denominated in foreign currencies and therefore, changes in the value of a country’s currency compared to the U.S. dollar may affect the value of an underlying fund’s investments. To the extent that an underlying fund invests a significant portion of its assets in the securities of issuers in or companies of a single country or region, it is more likely to be impacted by events or conditions affecting that country or region, which could have a negative impact on the Fund’s performance. Some of the risks of investing directly in foreign and emerging market securities may be reduced when an underlying fund invests indirectly in foreign securities through various other investment vehicles including derivatives, which also involve other risks.

Sovereign Debt Risk. An underlying fund may invest in U.S. and foreign government debt securities (“sovereign debt”). Investments in U.S. sovereign debt are considered low risk. However, investments in non-U.S. sovereign debt can involve a high degree of risk, including the risk that the governmental entity that controls the repayment of sovereign debt may not be willing or able to repay the principal and/or to pay the interest on its sovereign debt in a timely manner. A sovereign debtor’s willingness or ability to satisfy its debt obligation may be affected by various factors including, but not limited to, its cash flow situation, the extent of its foreign currency reserves, the availability of foreign exchange when a payment is due, and the relative size of its debt position in relation to its economy as a whole. In the event of default, there may be limited or no legal remedies for collecting sovereign debt and there may be no bankruptcy proceedings through which the underlying fund may collect all or part of the sovereign debt that a governmental entity has not repaid.

Fixed-Income Securities Risk. Approximately 15% of the Fund’s assets are allocated to fixed-income securities through investments in underlying funds. Typically, the values of fixed-income securities change inversely with prevailing interest rates. Therefore, a fundamental risk of fixed-income securities is interest rate risk, which is the risk that the value of such securities will generally decline as prevailing interest rates rise, which may cause an underlying fund’s net asset value to likewise decrease. How specific fixed-income securities may react to changes in interest rates will depend on the specific characteristics of each security. Fixed-income securities are also subject to credit risk, prepayment risk, valuation risk, and liquidity risk. Credit risk is the risk that the credit strength of an issuer of a fixed-income security will weaken and/or that the issuer will be unable to make timely principal and interest payments and that the security may go into default. Prepayment risk is the risk that during periods of falling interest rates, certain fixed-income securities with higher interest rates, such as mortgage- and asset-backed securities, may be prepaid by their issuers thereby reducing the amount of interest payments. Valuation risk is the risk that one or more of the fixed-income securities in which an underlying fund invests are priced differently than the value realized upon such security’s sale. In times of market instability, valuation may be more difficult. Liquidity risk is the risk that fixed-income securities may be difficult or impossible to sell at the time that an underlying fund’s portfolio manager would like or at the price the portfolio manager believes the security is currently worth.

Mortgage-Backed Securities Risk. Mortgage-backed securities are classified generally as either commercial mortgage-backed securities or residential mortgage-backed securities, each of which is subject to certain specific risks. Mortgage-backed securities tend to be more sensitive to changes in interest rates than other types of debt securities. Investments in mortgage-backed securities are subject to both extension risk, where borrowers extend the duration of their mortgages in times of rising interest rates, and prepayment risk, where borrowers pay off their mortgages sooner than expected in times of declining interest rates. These risks may reduce the Fund’s returns. In addition, investments in mortgage-backed securities, including those comprised of subprime mortgages, may be subject to a higher degree of credit risk, valuation risk, and liquidity risk than various other types of fixed-income securities.

Alternative Investments Allocation Risk. Approximately 10% of the Fund’s assets are allocated to alternative investments through investments in underlying funds that invest in alternative investment strategies. In connection with the Fund’s allocation to alternative investments, the Fund may invest in a Janus underlying fund, Janus Diversified Alternatives Fund, which seeks returns uncorrelated with the returns generated by investments in stocks and bonds. In addition, as part of its alternative investments allocation, the Fund may invest in Janus Global Real Estate Fund. Janus Diversified Alternatives Fund’s ability to achieve its investment objective depends largely upon the successful evaluation of the risk, potential returns, and correlation properties with respect to its investments. There is a risk that the returns provided by alternative investments may be subject to high volatility and that an underlying fund’s portfolio manager’s beliefs about the expected returns, risk and correlation properties of one or more of an underlying fund’s investments may be incorrect. There is also a risk that an underlying fund’s investments will correlate with the performance of stocks and bonds to a greater degree than anticipated. Janus Capital does not have prior experience managing the investment strategy of Janus Diversified Alternatives Fund, and there is no guarantee that the investment techniques and analysis used by the underlying fund’s portfolio managers will produce the desired results. All of these factors may negatively affect your investment in the Fund and you could lose money. Investment in the underlying funds also involves derivatives, counterparty, leverage, real estate-related, and commodity-linked investment risks.

Counterparty Risk. Certain derivative and “over-the-counter” instruments, such as swaps and forwards, are subject to the risk that the other party to a contract will not fulfill its contractual obligations.

Commodity-Linked Investments Risk. Certain underlying funds may invest in derivatives that have exposure to the commodities markets. Such exposure may subject an underlying fund to greater volatility than investments in traditional securities. The value of a commodity-linked derivative investment typically is based upon the price movements of a physical commodity (such as heating oil, livestock, or agricultural products), a commodity futures contract or commodity index, or some other readily measurable economic variable. The value of commodity-linked derivative instruments may therefore be affected by changes in overall market movements, volatility of the underlying benchmark, changes in interest rates, or other factors affecting a particular industry or commodity such as drought, floods, weather, livestock disease, embargoes, tariffs, and international economic, political, and regulatory developments.

Derivatives Risk. Certain underlying funds may invest in derivatives. Derivatives can be highly volatile and involve risks in addition to the risks of the underlying referenced securities. Gains or losses from a derivative investment can be substantially greater than the derivative’s original cost, and can therefore involve leverage. Leverage may cause an underlying fund to be more volatile than if it had not used leverage. Derivatives can be less liquid than other types of investments and entail the risk that the counterparty will default on its payment obligations.

Exchange-Traded Funds Risk. Certain underlying funds may purchase shares of exchange-traded funds (“ETFs”) to gain exposure to a particular portion of the market. ETFs are pooled investment vehicles, which may be managed or unmanaged, that generally seek to track the performance of a specific index. ETFs are traded on an exchange at market prices that may vary from the net asset value of their underlying investments. When an underlying fund invests in an ETF, in addition to directly bearing the expenses associated with its own operations, it will bear a pro rata portion of the ETF’s expenses. ETFs have certain inherent risks generally associated with investments in a portfolio of securities in which the ETF is invested, including the risk that the general level of stock prices may decline, thereby adversely affecting the value of each unit of the ETF. ETFs also involve the risk that an active trading market for an ETF’s shares may not develop or be maintained.

Exchange-Traded Notes Risk. Certain underlying funds may invest in exchange-traded notes (“ETNs”), which are debt securities whose returns are linked to a particular index. ETNs are typically linked to the performance of a commodities index that reflects the potential return on unleveraged investments in futures contracts of physical commodities, plus a specified rate of interest that could be earned on cash collateral. ETNs are subject to credit risk and counterparty risk. The value of an ETN may vary and may be influenced by time to maturity, level of supply and demand for the ETN, volatility and lack of liquidity in underlying commodities markets, changes in the applicable interest rates, changes in the issuer’s credit rating, and economic, legal, political, or geographic events that affect the referenced commodity. When an underlying fund invests in ETNs it will bear its proportionate share of any fees and expenses borne by the ETN. There may be restrictions on an underlying fund’s right to redeem its investment in an ETN, which is meant to be held until maturity. An underlying fund’s decision to sell its ETN holdings may be limited by the availability of a secondary market.

An investment in the Fund is not a bank deposit and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency.

PERFORMANCE INFORMATION

The following information provides some indication of the risks of investing in the Fund by showing how the Fund’s performance has varied over time. Class D Shares of the Fund commenced operations on February 16, 2010, as a result of the restructuring of Class J Shares, the predecessor share class. The performance shown for Class D Shares for periods prior to February 16, 2010, reflects the performance of the Fund’s former Class J Shares, calculated using the fees and expenses in effect during the periods shown, net of any applicable fee and expense limitations or waivers. If Class D Shares of the Fund had been available during periods prior to February 16, 2010, the performance shown may have been different. The performance shown for periods following the Fund’s commencement of Class D Shares reflects the fees and expenses of Class D Shares, net of any applicable fee and expense limitations or waivers.

The bar chart depicts the change in performance from year to year during the periods indicated. Performance information for each underlying fund is available in its prospectus and/or the most recent annual or semiannual report. The table compares the Fund’s average annual returns for the periods indicated to broad-based securities market indices. The indices are not actively managed and are not available for direct investment. All figures assume reinvestment of dividends and distributions. For certain periods, the Fund’s performance reflects the effect of expense waivers. Without the effect of these expense waivers, the performance shown would have been lower.

The Fund’s past performance (before and after taxes) does not necessarily indicate how it will perform in the future. Updated performance information is available at janus.com/allfunds or by calling 1-800-525-3713.

Annual Total Returns for Class D Shares (calendar year-end)

Best Quarter:  Second Quarter 2009  18.37%          Worst Quarter:  Fourth Quarter 2008  −18.05%

The Fund’s year-to-date return as of the calendar quarter ended September 30, 2013 was 12.38%.

Average Annual Total Returns (periods ended 12/31/12)

Average Annual Total Returns Janus Global Allocation Fund - Growth Class D Shares	Column	Label		1 Year	5 Years	Since Inception	Inception Date
Class D Return Before Taxes	Class D Shares	Return Before Taxes		14.93%	1.53%	5.75%	Dec. 30, 2005
Class D Return After Taxes on Distributions	Class D Shares	Return After Taxes on Distributions		14.42%	1.03%	5.15%	Dec. 30, 2005
Class D Return After Taxes on Distributions and Sale of Fund Shares	Class D Shares	Return After Taxes on Distributions and Sale of Fund Shares	[1]	10.00%	1.06%	4.71%	Dec. 30, 2005
Morgan Stanley Capital International All Country World Index℠ (net of foreign withholding taxes) (reflects no deduction for expenses, fees, or taxes, except foreign withholding taxes)		Morgan Stanley Capital International All Country World IndexSM (net of foreign withholding taxes)		16.13%	(1.16%)	3.52%	Dec. 30, 2005
Global Growth Allocation Index (reflects no deduction for expenses, fees, or taxes, except any applicable foreign withholding taxes)		Global Growth Allocation Index		13.80%	0.43%	4.30%	Dec. 30, 2005
S&P 500® Index (reflects no deduction for expenses, fees, or taxes)		S&P 500® Index		16.00%	1.66%	4.12%	Dec. 30, 2005
Growth Allocation Index (reflects no deduction for expenses, fees, or taxes, except any applicable foreign withholding taxes)		Growth Allocation Index		14.29%	1.76%	4.81%	Dec. 30, 2005

Effective February 15, 2013, the Fund’s primary benchmark index changed from the S&P 500^® Index to the Morgan Stanley Capital International (“MSCI”) All Country World Index^SM to reflect the global investment strategies of the Fund. Additionally, the Fund changed the name of its secondary benchmark index from Growth Allocation Index to Global Growth Allocation Index and its composition from an internally-calculated, hypothetical combination of unmanaged indices that combines total returns from the Dow Jones Wilshire 5000 Index (50%), the MSCI EAFE^® Index (25%), the Barclays U.S. Aggregate Bond Index (20%), and the MSCI Emerging Markets Free Index^SM (5%) to an internally-calculated, hypothetical combination of unmanaged indices that combines total returns from the MSCI All Country World Index^SM (80%) and the Barclays Global Aggregate Bond Index (20%). The MSCI All Country World Index^SM is an unmanaged, free float-adjusted market capitalization weighted index that is designed to measure the equity market performance of global developed and emerging markets. Janus Capital believes that the foregoing benchmark index changes provide a more appropriate representation of the Fund’s revised investment strategy that includes an increased focus on global investments, including emerging markets.

After-tax returns are calculated using distributions for the Fund’s Class D Shares for the periods following February 16, 2010; and for the Fund’s Class J Shares, the predecessor share class, for the periods prior to February 16, 2010. If Class D Shares of the Fund had been available during these earlier periods, distributions may have been different and thus, after-tax returns may have been different from those shown. After-tax returns are calculated using the historically highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes. Actual after-tax returns depend on your individual tax situation and may differ from those shown in the preceding table. The after-tax return information shown above does not apply to Fund shares held through a tax-deferred account, such as a 401(k) plan or an IRA.

[1] If the Fund incurs a loss, which generates a tax benefit, the Return After Taxes on Distributions and Sale of Fund Shares may exceed the Fund’s other return figures.

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Janus Global Allocation Fund - Conservative | Class D Shares

FUND SUMMARY

Janus Global Allocation Fund – Conservative
(formerly named Janus Conservative Allocation Fund)

INVESTMENT OBJECTIVE

Janus Global Allocation Fund – Conservative seeks total return through a primary emphasis on income with a secondary emphasis on growth of capital.

FEES AND EXPENSES OF THE FUND

This table describes the fees and expenses that you may pay if you buy and hold Shares of the Fund.

ANNUAL FUND OPERATING EXPENSES
(expenses that you pay each year as a percentage of the value of your investment)

Annual Fund Operating Expenses	Janus Global Allocation Fund - Conservative Class D Shares Class D
Operating Expenses Column [Text]	Class D
Management Fees	0.05%
Other Expenses	0.20%
Acquired Fund Fees and Expenses	0.60%
Total Annual Fund Operating Expenses	0.85%

EXAMPLE:

The Example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds.

The Example assumes that you invest $10,000 in the Fund for the time periods indicated, reinvest all dividends and distributions, and then redeem all of your Shares at the end of each period. The Example also assumes that your investment has a 5% return each year and that the Fund’s operating expenses (including the operating expenses of the underlying funds) remain the same. Although your actual costs may be higher or lower, based on these assumptions your costs would be:

Expense Example (USD $)	Expense Example, By Year, Column [Text]	1 Year	3 Years	5 Years	10 Years
Janus Global Allocation Fund - Conservative Class D Shares Class D	Class D Shares	87	271	471	1,049

Portfolio Turnover: 

The Fund pays transaction costs, such as commissions, when it buys and sells securities (or “turns over” its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when Fund shares are held in a taxable account. These costs, which are not reflected in annual fund operating expenses or in the Example, affect the Fund’s performance. During the most recent fiscal year, the Fund’s portfolio turnover rate was 69% of the average value of its portfolio.

PRINCIPAL INVESTMENT STRATEGIES

The Fund seeks to achieve its investment objective by investing in other Janus mutual funds (“underlying funds”) that represent a variety of asset classes and investment styles and provide exposure to issuers that are economically tied to countries throughout the world. Through its investments in underlying funds, the Fund invests in issuers from several different countries and may, under unusual circumstances, be invested in a single country. As a result, the Fund normally will have approximately 40% of its net assets allocated to non-U.S. investments. The Fund may also have significant exposure to emerging markets.

The Fund pursues this objective by investing in a diversified portfolio of underlying funds, resulting in an allocation of the Fund’s investments that normally provides exposure of approximately 55% to fixed-income securities and money market instruments, 40% to equity investments, and 5% to alternative investments. The target allocation and the allocation of the Fund’s assets among underlying funds are based on quantitative and qualitative analysis. Because it invests in other funds, the Fund is considered a “fund of funds.”

The Fund’s asset allocation is intended to diversify investments throughout the world among equity investments, fixed-income securities, cash equivalents, and alternative investments. The portfolio manager determines the overall composition of the Fund, oversees the investment process, and is responsible for the day-to-day management of the Fund. The portfolio manager continually monitors asset class allocations and periodically rebalances the Fund’s investments in the underlying funds. The portfolio manager also regularly reviews the allocation of Fund assets in the underlying funds and may modify the underlying funds’ weightings or substitute other underlying funds to emphasize and mitigate risk exposures that may arise as a result of the implementation of the allocations. An independent asset allocation service provides evaluations of asset allocations that the portfolio manager may use in implementing the allocations among the underlying funds.

Additionally, the portfolio manager consults with a committee (the “Janus Global Allocation Committee”) to regularly review the broad market, macroeconomic conditions and other global financial factors that may impact the Fund’s allocation of assets among the underlying funds and asset classes. The Janus Global Allocation Committee is comprised of investment professionals of Janus Capital and may also include investment professionals of Janus Capital’s affiliated investment advisers. The portfolio manager and Janus Global Allocation Committee normally meet on a quarterly basis. The portfolio manager may change the Fund’s asset class allocations, the underlying funds, an underlying fund’s asset category, or weightings among asset classes or underlying funds without prior shareholder notice.

The Fund will normally allocate approximately 55% of its investments to underlying bond funds and money market instruments, approximately 40% of its investments to underlying funds that provide varying exposure to common stocks of large U.S.-based companies, small- to mid-capitalization companies, and international companies (including those with exposure to emerging markets), and approximately 5% of its investments to underlying funds that seek returns uncorrelated with the returns of stocks and bonds by providing exposure to alternative investments and alternative investment strategies. Refer to Appendix A in this Prospectus for a brief description of the investment strategies of each of the currently available underlying funds.

When market conditions dictate a more defensive strategy, the Fund or an underlying fund may temporarily hold cash or invest its assets in temporary investments. In that case, the Fund may take positions that are inconsistent with its investment objective. As a result, the Fund may not achieve its investment objective.

PRINCIPAL INVESTMENT RISKS

The biggest risk is that the Fund’s returns will vary, and you could lose money. The Fund is designed for long-term investors seeking income and, to a lesser extent, growth of capital. Investments in a portfolio with common stock and alternative investment exposure tend to be more volatile than many other investment choices.

Main Risks Associated with the Fund
Allocation Risk. The Fund’s ability to achieve its investment objective depends largely upon the portfolio manager’s allocation of assets among the underlying funds and other securities, using the optimization process (a process that utilizes quantitative analysis of a number of factors, such as historical risk, performance, fund classifications, and the relationship among underlying funds) and the judgment of the portfolio manager. You could lose money on your investment in the Fund as a result of these allocations. The Fund will typically invest in a number of different underlying funds; however, to the extent that the Fund invests a significant portion of its assets in a single underlying fund, it will be more sensitive to the risks associated with that fund and any investments in which that fund focuses.

Affiliated Fund Risk. Janus Capital has the authority to select and substitute underlying affiliated mutual funds. The fees paid to Janus Capital by some Janus mutual funds are generally higher than the fees paid to Janus Capital by the Fund or by other funds and share classes available for investment by the Fund. These conditions may create a conflict of interest when selecting underlying affiliated mutual funds and share classes for investment. Janus Capital, however, is a fiduciary to the Fund and its shareholders and is legally obligated to act in their best interest when selecting underlying affiliated mutual funds.

Main Risks Associated with the Underlying Funds and Securities
The biggest risk is that the underlying funds’ returns will vary, and you could lose money.

Fixed-Income Securities Risk. Approximately 55% of the Fund’s assets are allocated to fixed-income securities through investments in underlying funds. Typically, the values of fixed-income securities change inversely with prevailing interest rates. Therefore, a fundamental risk of fixed-income securities is interest rate risk, which is the risk that the value of such securities will generally decline as prevailing interest rates rise, which may cause an underlying fund’s net asset value to likewise decrease. How specific fixed-income securities may react to changes in interest rates will depend on the specific characteristics of each security. Fixed-income securities are also subject to credit risk, prepayment risk, valuation risk, and liquidity risk. Credit risk is the risk that the credit strength of an issuer of a fixed-income security will weaken and/or that the issuer will be unable to make timely principal and interest payments and that the security may go into default. Prepayment risk is the risk that during periods of falling interest rates, certain fixed-income securities with higher interest rates, such as mortgage- and asset-backed securities, may be prepaid by their issuers thereby reducing the amount of interest payments. Valuation risk is the risk that one or more of the fixed-income securities in which an underlying fund invests are priced differently than the value realized upon such security’s sale. In times of market instability, valuation may be more difficult. Liquidity risk is the risk that fixed-income securities may be difficult or impossible to sell at the time that an underlying fund’s portfolio manager would like or at the price the portfolio manager believes the security is currently worth.

Mortgage-Backed Securities Risk. Mortgage-backed securities are classified generally as either commercial mortgage-backed securities or residential mortgage-backed securities, each of which is subject to certain specific risks. Mortgage-backed securities tend to be more sensitive to changes in interest rates than other types of debt securities. Investments in mortgage-backed securities are subject to both extension risk, where borrowers extend the duration of their mortgages in times of rising interest rates, and prepayment risk, where borrowers pay off their mortgages sooner than expected in times of declining interest rates. These risks may reduce the Fund’s returns. In addition, investments in mortgage-backed securities, including those comprised of subprime mortgages, may be subject to a higher degree of credit risk, valuation risk, and liquidity risk than various other types of fixed-income securities.

Market Risk. Approximately 40% of the Fund’s assets are allocated to equity investments through investments in underlying funds. The value of an underlying fund’s portfolio may decrease if the value of an individual company or security, or multiple companies or securities, in the portfolio decreases or if a portfolio manager’s belief about a company’s intrinsic worth is incorrect. Further, regardless of how well individual companies or securities perform, the value of an underlying fund’s portfolio could also decrease if there are deteriorating economic or market conditions. It is important to understand that the value of your investment may fall, sometimes sharply, in response to changes in the market, and you could lose money.

Foreign Exposure Risk. Certain underlying funds may have significant exposure to foreign markets as a result of their investments in foreign securities, including investments in emerging markets, which can be more volatile than the U.S. markets. As a result, an underlying fund’s returns and net asset value may be affected to a large degree by fluctuations in currency exchange rates or political or economic conditions in a particular country. A market swing in one or more countries or regions where an underlying fund has invested a significant amount of its assets may have a greater effect on an underlying fund’s performance than it would in a more geographically diversified portfolio. An underlying fund’s investments in emerging market countries may involve risks greater than, or in addition to, the risks of investing in more developed countries.

Emerging Markets Risk. The risks of foreign investing mentioned above are heightened when investing in emerging markets. Emerging markets securities involve a number of additional risks, which may result from less government supervision and regulation of business and industry practices (including the potential lack of strict finance and accounting controls and standards), stock exchanges, brokers, and listed companies, making these investments potentially more volatile in price and less liquid than investments in developed securities markets, resulting in greater risk to investors. In addition, an underlying fund’s investments may be denominated in foreign currencies and therefore, changes in the value of a country’s currency compared to the U.S. dollar may affect the value of an underlying fund’s investments. To the extent that an underlying fund invests a significant portion of its assets in the securities of issuers in or companies of a single country or region, it is more likely to be impacted by events or conditions affecting that country or region, which could have a negative impact on the Fund’s performance. Some of the risks of investing directly in foreign and emerging market securities may be reduced when an underlying fund invests indirectly in foreign securities through various other investment vehicles including derivatives, which also involve other risks.

Sovereign Debt Risk. An underlying fund may invest in U.S. and foreign government debt securities (“sovereign debt”). Investments in U.S. sovereign debt are considered low risk. However, investments in non-U.S. sovereign debt can involve a high degree of risk, including the risk that the governmental entity that controls the repayment of sovereign debt may not be willing or able to repay the principal and/or to pay the interest on its sovereign debt in a timely manner. A sovereign debtor’s willingness or ability to satisfy its debt obligation may be affected by various factors including, but not limited to, its cash flow situation, the extent of its foreign currency reserves, the availability of foreign exchange when a payment is due, and the relative size of its debt position in relation to its economy as a whole. In the event of default, there may be limited or no legal remedies for collecting sovereign debt and there may be no bankruptcy proceedings through which the underlying fund may collect all or part of the sovereign debt that a governmental entity has not repaid.

Alternative Investments Allocation Risk. Approximately 5% of the Fund’s assets are allocated to alternative investments through investments in underlying funds that invest in alternative investment strategies. In connection with the Fund’s allocation to alternative investments, the Fund may invest in a Janus underlying fund, Janus Diversified Alternatives Fund, which seeks returns uncorrelated with the returns generated by investments in stocks and bonds. In addition, as part of its alternative investments allocation, the Fund may invest in Janus Global Real Estate Fund. Janus Diversified Alternatives Fund’s ability to achieve its investment objective depends largely upon the successful evaluation of the risk, potential returns, and correlation properties with respect to its investments. There is a risk that the returns provided by alternative investments may be subject to high volatility and that an underlying fund’s portfolio manager’s beliefs about the expected returns, risk and correlation properties of one or more of an underlying fund’s investments may be incorrect. There is also a risk that an underlying fund’s investments will correlate with the performance of stocks and bonds to a greater degree than anticipated. Janus Capital does not have prior experience managing the investment strategy of Janus Diversified Alternatives Fund, and there is no guarantee that the investment techniques and analysis used by the underlying fund’s portfolio managers will produce the desired results. All of these factors may negatively affect your investment in the Fund and you could lose money. Investment in the underlying funds also involves derivatives, counterparty, leverage, real estate-related, and commodity-linked investment risks.

Counterparty Risk. Certain derivative and “over-the-counter” instruments, such as swaps and forwards, are subject to the risk that the other party to a contract will not fulfill its contractual obligations.

Commodity-Linked Investments Risk. Certain underlying funds may invest in derivatives that have exposure to the commodities markets. Such exposure may subject an underlying fund to greater volatility than investments in traditional securities. The value of a commodity-linked derivative investment typically is based upon the price movements of a physical commodity (such as heating oil, livestock, or agricultural products), a commodity futures contract or commodity index, or some other readily measurable economic variable. The value of commodity-linked derivative instruments may therefore be affected by changes in overall market movements, volatility of the underlying benchmark, changes in interest rates, or other factors affecting a particular industry or commodity such as drought, floods, weather, livestock disease, embargoes, tariffs, and international economic, political, and regulatory developments.

Derivatives Risk. Certain underlying funds may invest in derivatives. Derivatives can be highly volatile and involve risks in addition to the risks of the underlying referenced securities. Gains or losses from a derivative investment can be substantially greater than the derivative’s original cost, and can therefore involve leverage. Leverage may cause an underlying fund to be more volatile than if it had not used leverage. Derivatives can be less liquid than other types of investments and entail the risk that the counterparty will default on its payment obligations.

Exchange-Traded Funds Risk. Certain underlying funds may purchase shares of exchange-traded funds (“ETFs”) to gain exposure to a particular portion of the market. ETFs are pooled investment vehicles, which may be managed or unmanaged, that generally seek to track the performance of a specific index. ETFs are traded on an exchange at market prices that may vary from the net asset value of their underlying investments. When an underlying fund invests in an ETF, in addition to directly bearing the expenses associated with its own operations, it will bear a pro rata portion of the ETF’s expenses. ETFs have certain inherent risks generally associated with investments in a portfolio of securities in which the ETF is invested, including the risk that the general level of stock prices may decline, thereby adversely affecting the value of each unit of the ETF. ETFs also involve the risk that an active trading market for an ETF’s shares may not develop or be maintained.

Exchange-Traded Notes Risk. Certain underlying funds may invest in exchange-traded notes (“ETNs”), which are debt securities whose returns are linked to a particular index. ETNs are typically linked to the performance of a commodities index that reflects the potential return on unleveraged investments in futures contracts of physical commodities, plus a specified rate of interest that could be earned on cash collateral. ETNs are subject to credit risk and counterparty risk. The value of an ETN may vary and may be influenced by time to maturity, level of supply and demand for the ETN, volatility and lack of liquidity in underlying commodities markets, changes in the applicable interest rates, changes in the issuer’s credit rating, and economic, legal, political, or geographic events that affect the referenced commodity. When an underlying fund invests in ETNs it will bear its proportionate share of any fees and expenses borne by the ETN. There may be restrictions on an underlying fund’s right to redeem its investment in an ETN, which is meant to be held until maturity. An underlying fund’s decision to sell its ETN holdings may be limited by the availability of a secondary market.

An investment in the Fund is not a bank deposit and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency.

PERFORMANCE INFORMATION

The following information provides some indication of the risks of investing in the Fund by showing how the Fund’s performance has varied over time. Class D Shares of the Fund commenced operations on February 16, 2010, as a result of the restructuring of Class J Shares, the predecessor share class. The performance shown for Class D Shares for periods prior to February 16, 2010, reflects the performance of the Fund’s former Class J Shares, calculated using the fees and expenses in effect during the periods shown, net of any applicable fee and expense limitations or waivers. If Class D Shares of the Fund had been available during periods prior to February 16, 2010, the performance shown may have been different. The performance shown for periods following the Fund’s commencement of Class D Shares reflects the fees and expenses of Class D Shares, net of any applicable fee and expense limitations or waivers.

The bar chart depicts the change in performance from year to year during the periods indicated. Performance information for each underlying fund is available in its prospectus and/or the most recent annual or semiannual report. The table compares the Fund’s average annual returns for the periods indicated to broad-based securities market indices. The indices are not actively managed and are not available for direct investment. All figures assume reinvestment of dividends and distributions. For certain periods, the Fund’s performance reflects the effect of expense waivers. Without the effect of these expense waivers, the performance shown would have been lower.

The Fund’s past performance (before and after taxes) does not necessarily indicate how it will perform in the future. Updated performance information is available at janus.com/allfunds or by calling 1-800-525-3713.

Annual Total Returns for Class D Shares (calendar year-end)

Best Quarter:  Second Quarter 2009  10.64%          Worst Quarter:  Third Quarter 2008  −6.58%

The Fund’s year-to-date return as of the calendar quarter ended September 30, 2013 was 6.60%.

Average Annual Total Returns (periods ended 12/31/12)

Average Annual Total Returns Janus Global Allocation Fund - Conservative Class D Shares	Column	Label	1 Year	5 Years	Since Inception	Inception Date
Class D Return Before Taxes	Class D Shares	Return Before Taxes	10.89%	5.24%	6.75%	Dec. 30, 2005
Class D Return After Taxes on Distributions	Class D Shares	Return After Taxes on Distributions	9.95%	4.18%	5.72%	Dec. 30, 2005
Class D Return After Taxes on Distributions and Sale of Fund Shares	Class D Shares	Return After Taxes on Distributions and Sale of Fund Shares	7.22%	3.88%	5.26%	Dec. 30, 2005
Barclays Global Aggregate Bond Index (reflects no deduction for expenses, fees, or taxes)		Barclays Global Aggregate Bond Index	4.32%	5.44%	6.18%	Dec. 30, 2005
Global Conservative Allocation Index (reflects no deduction for expenses, fees, or taxes, except any applicable foreign withholding taxes)		Global Conservative Allocation Index	9.09%	3.22%	5.48%	Dec. 30, 2005
S&P 500® Index (reflects no deduction for expenses, fees, or taxes)		S&P 500® Index	16.00%	1.66%	4.12%	Dec. 30, 2005
Conservative Allocation Index (reflects no deduction for expenses, fees, or taxes, except any applicable foreign withholding taxes)		Conservative Allocation Index	9.21%	4.26%	5.49%	Dec. 30, 2005

Effective February 15, 2013, the Fund’s primary benchmark index changed from the S&P 500^® Index to the Barclays Global Aggregate Bond Index to reflect the global investment strategies of the Fund. Additionally, the Fund changed the name of its secondary benchmark index from Conservative Allocation Index to Global Conservative Allocation Index and its composition from an internally-calculated, hypothetical combination of unmanaged indices that combines total returns from the Barclays U.S. Aggregate Bond Index (60%), the Dow Jones Wilshire 5000 Index (28%), and the Morgan Stanley Capital International Europe, Australasia, Far East Index (“MSCI EAFE^®”) Index (12%) to an internally-calculated, hypothetical combination of unmanaged indices that combines total returns from the Barclays Global Aggregate Bond Index (60%) and the Morgan Stanley Capital International All Country World Index^SM (40%). The Barclays Global Aggregate Bond Index is an index that provides a broad-based measure of the global investment grade fixed-rate debt markets. Janus Capital believes that the foregoing benchmark index changes provide a more appropriate representation of the Fund’s revised investment strategy that includes an increased focus on global investments, including emerging markets.

After-tax returns are calculated using distributions for the Fund’s Class D Shares for the periods following February 16, 2010; and for the Fund’s Class J Shares, the predecessor share class, for the periods prior to February 16, 2010. If Class D Shares of the Fund had been available during these earlier periods, distributions may have been different and thus, after-tax returns may have been different from those shown. After-tax returns are calculated using the historically highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes. Actual after-tax returns depend on your individual tax situation and may differ from those shown in the preceding table. The after-tax return information shown above does not apply to Fund shares held through a tax-deferred account, such as a 401(k) plan or an IRA.

XML

Label	Element	Value
Risk/Return:	rr_RiskReturnAbstract
Registrant Name	dei_EntityRegistrantName	JANUS INVESTMENT FUND
Prospectus Date	rr_ProspectusDate	Oct. 28, 2013
Perkins Mid Cap Value Fund | Class D Shares
Risk/Return:	rr_RiskReturnAbstract
Risk/Return [Heading]	rr_RiskReturnHeading	FUND SUMMARY Perkins Mid Cap Value Fund
Objective [Heading]	rr_ObjectiveHeading	INVESTMENT OBJECTIVE
Objective, Primary [Text Block]	rr_ObjectivePrimaryTextBlock	Perkins Mid Cap Value Fund seeks capital appreciation.
Expense [Heading]	rr_ExpenseHeading	FEES AND EXPENSES OF THE FUND
Expense Narrative [Text Block]	rr_ExpenseNarrativeTextBlock	This table describes the fees and expenses that you may pay if you buy and hold Shares of the Fund.
Operating Expenses Caption [Text]	rr_OperatingExpensesCaption	ANNUAL FUND OPERATING EXPENSES (expenses that you pay each year as a percentage of the value of your investment)
Portfolio Turnover [Heading]	rr_PortfolioTurnoverHeading	Portfolio Turnover:
Portfolio Turnover [Text Block]	rr_PortfolioTurnoverTextBlock	The Fund pays transaction costs, such as commissions, when it buys and sells securities (or “turns over” its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when Fund shares are held in a taxable account. These costs, which are not reflected in annual fund operating expenses or in the Example, affect the Fund’s performance. During the most recent fiscal year, the Fund’s portfolio turnover rate was 60% of the average value of its portfolio.
Portfolio Turnover, Rate	rr_PortfolioTurnoverRate	60.00%
Expense Example [Heading]	rr_ExpenseExampleHeading	EXAMPLE:
Expense Example by Year [Heading]	rr_ExpenseExampleByYearHeading	The Example assumes that you invest $10,000 in the Fund for the time periods indicated, reinvest all dividends and distributions, and then redeem all of your Shares at the end of each period. The Example also assumes that your investment has a 5% return each year and that the Fund’s operating expenses remain the same. Although your actual costs may be higher or lower, based on these assumptions your costs would be:
Expense Example Narrative [Text Block]	rr_ExpenseExampleNarrativeTextBlock	The Example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds.
Strategy [Heading]	rr_StrategyHeading	PRINCIPAL INVESTMENT STRATEGIES
Strategy Narrative [Text Block]	rr_StrategyNarrativeTextBlock	The Fund pursues its investment objective by investing primarily in common stocks selected for their capital appreciation potential. The Fund primarily invests in the common stocks of mid-sized companies whose stock prices the portfolio managers believe to be undervalued. The Fund invests, under normal circumstances, at least 80% of its net assets in equity securities of companies whose market capitalization falls, at the time of purchase, within the 12-month average of the capitalization range of the Russell Midcap® Value Index. This average is updated monthly. The market capitalizations within the index will vary, but as of June 30, 2013, they ranged from approximately $487 million to $30.3 billion. The Fund may also invest in foreign equity and debt securities, which may include investments in emerging markets. The Fund may invest, under normal circumstances, up to 20% of its net assets in securities of companies having market capitalizations outside of the aforementioned market capitalization ranges. In addition, when the portfolio managers believe that market conditions are unfavorable for investing, or when they are otherwise unable to locate attractive investment opportunities, the Fund may invest up to 20% of its net assets in cash or similar investments. The Fund focuses on companies that have fallen out of favor with the market or that appear to be temporarily misunderstood by the investment community. The Fund’s portfolio managers generally look for companies with: strong balance sheets and solid recurring free cash flows attractive relative and absolute valuation ratios or that have underperformed recently favorable reward to risk characteristics The Fund may invest in equity and debt securities of real estate-related companies. Such companies may include those in the real estate industry or real estate-related industries. These securities may include common stocks, preferred stocks, and other equity securities, including, but not limited to, mortgage-backed securities, real estate-backed securities, securities of real estate investment trusts (“REITs”) and similar REIT-like entities. A REIT is a trust that invests in real estate-related projects, such as properties, mortgage loans, and construction loans. REITs are generally categorized as equity, mortgage, or hybrid REITs. A REIT may be listed on an exchange or traded over-the-counter. The Fund may also invest its assets in derivatives, which are instruments that have a value derived from, or directly linked to, an underlying asset, such as equity securities, fixed-income securities, commodities, currencies, interest rates, or market indices. The Fund from time to time may buy and sell put and call options, particularly on market indices, for hedging purposes (to offset risks associated with an investment, currency exposure, or market conditions) and to enhance returns. The Fund’s exposure to derivatives will vary, is not limited to those derivatives listed, and could be significant at times. For purposes of meeting its 80% investment policy, the Fund may include derivatives that have characteristics similar to the securities in which the Fund may directly invest.
Risk [Heading]	rr_RiskHeading	PRINCIPAL INVESTMENT RISKS
Risk Narrative [Text Block]	rr_RiskNarrativeTextBlock	The biggest risk is that the Fund’s returns will vary, and you could lose money. The Fund is designed for long-term investors seeking an equity portfolio, including common stocks. Common stocks tend to be more volatile than many other investment choices. Value Investing Risk. Because different types of stocks tend to shift in and out of favor depending on market and economic conditions, “value” stocks may perform differently than other types of stocks and from the market as a whole, and can continue to be undervalued by the market for long periods of time. It is also possible that a value stock will never appreciate to the extent expected by the portfolio managers. When the Fund’s investments in cash or similar investments increase due to a lack of favorable investment opportunities or other extraordinary factors, the Fund may not participate in market advances or declines to the same extent that it would if the Fund had been fully invested. Market Risk. The value of the Fund’s portfolio may decrease if the value of an individual company or security, or multiple companies or securities, in the portfolio decreases or if the portfolio managers’ belief about a company’s intrinsic worth is incorrect. Further, regardless of how well individual companies or securities perform, the value of the Fund’s portfolio could also decrease if there are deteriorating economic or market conditions. It is important to understand that the value of your investment may fall, sometimes sharply, in response to changes in the market, and you could lose money. Mid-Sized Companies Risk. The Fund’s investments in securities issued by mid-sized companies may involve greater risks than are customarily associated with larger, more established companies. Securities issued by mid-sized companies tend to be more volatile than securities issued by larger or more established companies and may underperform as compared to the securities of larger companies. Real Estate Securities Risk. The Fund’s performance may be affected by the risks associated with investments in real estate-related companies. The value of real estate-related companies’ securities is sensitive to changes in real estate values and rental income, property taxes, interest rates, tax and regulatory requirements, supply and demand, and the management skill and creditworthiness of the company. Investments in REITs involve the same risks as other real estate investments. In addition, a REIT could fail to qualify for tax-free pass-through of its income under the Internal Revenue Code or fail to maintain its exemption from registration under the Investment Company Act of 1940, as amended, which could produce adverse economic consequences for the REIT and its investors, including the Fund. Foreign Exposure Risk. The Fund may have exposure to foreign markets as a result of its investments in foreign securities, including investments in emerging markets, which can be more volatile than the U.S. markets. As a result, its returns and net asset value may be affected to a large degree by fluctuations in currency exchange rates or political or economic conditions in a particular country. In some foreign markets, there may not be protection against failure by other parties to complete transactions. It may not be possible for the Fund to repatriate capital, dividends, interest, and other income from a particular country or governmental entity. In addition, a market swing in one or more countries or regions where the Fund has invested a significant amount of its assets may have a greater effect on the Fund’s performance than it would in a more geographically diversified portfolio. To the extent the Fund invests in foreign debt securities, such investments are sensitive to changes in interest rates. Additionally, investments in securities of foreign governments involve the risk that a foreign government may not be willing or able to pay interest or repay principal when due. Derivatives Risk. Derivatives can be highly volatile and involve risks in addition to the risks of the underlying referenced securities. Gains or losses from a derivative investment can be substantially greater than the derivative’s original cost, and can therefore involve leverage. Leverage may cause the Fund to be more volatile than if it had not used leverage. Derivatives can be complex instruments and may involve analysis that differs from that required for other investment types used by the Fund. If the value of a derivative does not correlate well with the particular market or other asset class to which the derivative is intended to provide exposure, the derivative may not produce the anticipated result. Derivatives can also reduce the opportunity for gain or result in losses by offsetting positive returns in other investments. Derivatives can be less liquid than other types of investments and entail the risk that the counterparty will default on its payment obligations. If the counterparty to a derivative transaction defaults, the Fund would risk the loss of the net amount of the payments that it contractually is entitled to receive. To the extent the Fund enters into short derivative positions, the Fund may be exposed to risks similar to those associated with short sales, including the risk that the Fund’s losses are theoretically unlimited. An investment in the Fund is not a bank deposit and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency.
Risk Lose Money [Text]	rr_RiskLoseMoney	The biggest risk is that the Fund’s returns will vary, and you could lose money.
Risk Not Insured Depository Institution [Text]	rr_RiskNotInsuredDepositoryInstitution	An investment in the Fund is not a bank deposit and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency.
Bar Chart and Performance Table [Heading]	rr_BarChartAndPerformanceTableHeading	PERFORMANCE INFORMATION
Performance Narrative [Text Block]	rr_PerformanceNarrativeTextBlock	The following information provides some indication of the risks of investing in the Fund by showing how the Fund’s performance has varied over time. Class D Shares of the Fund commenced operations on February 16, 2010, as a result of the restructuring of Class J Shares. The performance shown for Class D Shares for periods prior to February 16, 2010, reflects the performance of the Fund’s former Class J Shares (formerly named Investor Shares). For the periods prior to April 21, 2003, the performance shown for Class D Shares reflects the historical performance of Berger Mid Cap Value Fund – Investor Shares (as a result of a prior reorganization of Berger Mid Cap Value Fund – Investor Shares into the Fund’s former Class J Shares). If Class D Shares of the Fund had been available during periods prior to February 16, 2010, the performance shown may have been different. The performance shown for periods following the Fund’s commencement of Class D Shares reflects the fees and expenses of Class D Shares, net of any applicable fee and expense limitations or waivers. The bar chart depicts the change in performance from year to year during the periods indicated. The table compares the Fund’s average annual returns for the periods indicated to a broad-based securities market index. The index is not actively managed and is not available for direct investment. All figures assume reinvestment of dividends and distributions. For certain periods, the Fund’s performance reflects the effect of expense waivers. Without the effect of these expense waivers, the performance shown would have been lower. The Fund’s past performance (before and after taxes) does not necessarily indicate how it will perform in the future. Updated performance information is available at janus.com/allfunds or by calling 1-800-525-3713.
Performance Information Illustrates Variability of Returns [Text]	rr_PerformanceInformationIllustratesVariabilityOfReturns	The following information provides some indication of the risks of investing in the Fund by showing how the Fund’s performance has varied over time. The bar chart depicts the change in performance from year to year during the periods indicated.
Performance Additional Market Index [Text]	rr_PerformanceAdditionalMarketIndex	The table compares the Fund’s average annual returns for the periods indicated to a broad-based securities market index. The index is not actively managed and is not available for direct investment. All figures assume reinvestment of dividends and distributions.
Performance Availability Phone [Text]	rr_PerformanceAvailabilityPhone	1-800-525-3713
Performance Availability Website Address [Text]	rr_PerformanceAvailabilityWebSiteAddress	janus.com/allfunds
Performance Past Does Not Indicate Future [Text]	rr_PerformancePastDoesNotIndicateFuture	The Fund’s past performance (before and after taxes) does not necessarily indicate how it will perform in the future.
Bar Chart [Heading]	rr_BarChartHeading	Annual Total Returns for Class D Shares (calendar year-end)
Bar Chart Closing [Text Block]	rr_BarChartClosingTextBlock	Best Quarter:  Second Quarter 2003  17.17%          Worst Quarter:  Fourth Quarter 2008  −19.63%
Year to Date Return, Label	rr_YearToDateReturnLabel	The Fund’s year-to-date return as of the calendar quarter ended September 30, 2013 was 17.47%.
Performance Table Heading	rr_PerformanceTableHeading	Average Annual Total Returns (periods ended 12/31/12)
Performance Table Uses Highest Federal Rate	rr_PerformanceTableUsesHighestFederalRate	After-tax returns are calculated using the historically highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes.
Performance Table Not Relevant to Tax Deferred	rr_PerformanceTableNotRelevantToTaxDeferred	Actual after-tax returns depend on your individual tax situation and may differ from those shown in the preceding table. The after-tax return information shown above does not apply to Fund shares held through a tax-deferred account, such as a 401(k) plan or an IRA.
Performance Table Explanation after Tax Higher	rr_PerformanceTableExplanationAfterTaxHigher	If the Fund incurs a loss, which generates a tax benefit, the Return After Taxes on Distributions and Sale of Fund Shares may exceed the Fund’s other return figures.
Performance Table Narrative	rr_PerformanceTableNarrativeTextBlock	The Russell Midcap® Value Index measures the performance of those Russell Midcap® companies with lower price-to-book ratios and lower forecasted growth values. The stocks are also members of the Russell 1000® Value Index. This index is used to calculate the performance fee adjustment. After-tax returns are calculated using distributions for the Fund’s Class D Shares for the periods following February 16, 2010; for the Fund’s Class J Shares (formerly named Investor Shares) for the period April 21, 2003 to February 16, 2010; and for Berger Mid Cap Value Fund – Investor Shares for periods prior to April 21, 2003. If Class D Shares of the Fund had been available during these earlier periods, distributions may have been different and thus, after-tax returns may have been different from those shown. After-tax returns are calculated using the historically highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes. Actual after-tax returns depend on your individual tax situation and may differ from those shown in the preceding table. The after-tax return information shown above does not apply to Fund shares held through a tax-deferred account, such as a 401(k) plan or an IRA.
Performance Table Closing [Text Block]	rr_PerformanceTableClosingTextBlock	Updated performance information is available at janus.com/allfunds or by calling 1-800-525-3713.
Perkins Mid Cap Value Fund | Class D Shares | Class D
Risk/Return:	rr_RiskReturnAbstract
Operating Expenses Column [Text]	rr_OperatingExpensesColumnName	Class D
Management Fees (may adjust up or down)	rr_ManagementFeesOverAssets	0.48%
Other Expenses	rr_OtherExpensesOverAssets	0.20%
Total Annual Fund Operating Expenses	rr_ExpensesOverAssets	0.68%
Expense Example, By Year, Column [Text]	rr_ExpenseExampleByYearColumnName	Class D Shares
1 Year	rr_ExpenseExampleYear01	$ 69
3 Years	rr_ExpenseExampleYear03	218
5 Years	rr_ExpenseExampleYear05	379
10 Years	rr_ExpenseExampleYear10	$ 847
2003	rr_AnnualReturn2003	39.33%
2004	rr_AnnualReturn2004	18.36%
2005	rr_AnnualReturn2005	10.36%
2006	rr_AnnualReturn2006	15.25%
2007	rr_AnnualReturn2007	7.43%
2008	rr_AnnualReturn2008	(27.33%)
2009	rr_AnnualReturn2009	30.37%
2010	rr_AnnualReturn2010	14.91%
2011	rr_AnnualReturn2011	(2.42%)
2012	rr_AnnualReturn2012	10.43%
Bar Chart, Year to Date Return, Date	rr_BarChartYearToDateReturnDate	Sep. 30, 2013
Bar Chart, Year to Date Return	rr_BarChartYearToDateReturn	17.47%
Highest Quarterly Return, Label	rr_HighestQuarterlyReturnLabel	Best Quarter:
Highest Quarterly Return, Date	rr_BarChartHighestQuarterlyReturnDate	Jun. 30, 2003
Highest Quarterly Return	rr_BarChartHighestQuarterlyReturn	17.17%
Lowest Quarterly Return, Label	rr_LowestQuarterlyReturnLabel	Worst Quarter:
Lowest Quarterly Return, Date	rr_BarChartLowestQuarterlyReturnDate	Dec. 31, 2008
Lowest Quarterly Return	rr_BarChartLowestQuarterlyReturn	(19.63%)
Perkins Mid Cap Value Fund | Class D Shares | Return Before Taxes | Class D
Risk/Return:	rr_RiskReturnAbstract
Column	rr_AverageAnnualReturnColumnName	Class D Shares
Label	rr_AverageAnnualReturnLabel	Return Before Taxes
1 Year	rr_AverageAnnualReturnYear01	10.43%
5 Years	rr_AverageAnnualReturnYear05	3.24%
10 Years	rr_AverageAnnualReturnYear10	10.21%
Since Inception of Predecessor Fund	rr_AverageAnnualReturnSinceInception	11.68%
Inception Date	rr_AverageAnnualReturnInceptionDate	Aug. 12, 1998
Perkins Mid Cap Value Fund | Class D Shares | Return After Taxes on Distributions | Class D
Risk/Return:	rr_RiskReturnAbstract
Column	rr_AverageAnnualReturnColumnName	Class D Shares
Label	rr_AverageAnnualReturnLabel	Return After Taxes on Distributions
1 Year	rr_AverageAnnualReturnYear01	9.72%
5 Years	rr_AverageAnnualReturnYear05	2.58%
10 Years	rr_AverageAnnualReturnYear10	9.02%
Since Inception of Predecessor Fund	rr_AverageAnnualReturnSinceInception	10.28%
Inception Date	rr_AverageAnnualReturnInceptionDate	Aug. 12, 1998
Perkins Mid Cap Value Fund | Class D Shares | Return After Taxes on Distributions and Sale of Fund Shares | Class D
Risk/Return:	rr_RiskReturnAbstract
Column	rr_AverageAnnualReturnColumnName	Class D Shares
Label	rr_AverageAnnualReturnLabel	Return After Taxes on Distributions and Sale of Fund Shares	[1]
1 Year	rr_AverageAnnualReturnYear01	7.72%
5 Years	rr_AverageAnnualReturnYear05	2.66%
10 Years	rr_AverageAnnualReturnYear10	8.70%
Since Inception of Predecessor Fund	rr_AverageAnnualReturnSinceInception	9.91%
Inception Date	rr_AverageAnnualReturnInceptionDate	Aug. 12, 1998
Perkins Mid Cap Value Fund | Class D Shares | Russell Midcap® Value Index (reflects no deduction for expenses, fees, or taxes)
Risk/Return:	rr_RiskReturnAbstract
Label	rr_AverageAnnualReturnLabel	Russell Midcap® Value Index
1 Year	rr_AverageAnnualReturnYear01	18.51%
5 Years	rr_AverageAnnualReturnYear05	3.79%
10 Years	rr_AverageAnnualReturnYear10	10.63%
Since Inception of Predecessor Fund	rr_AverageAnnualReturnSinceInception	8.42%
Inception Date	rr_AverageAnnualReturnInceptionDate	Aug. 12, 1998

[1] If the Fund incurs a loss, which generates a tax benefit, the Return After Taxes on Distributions and Sale of Fund Shares may exceed the Fund’s other return figures.

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Janus Government Money Market Fund | Class D Shares

FUND SUMMARY

Janus Government Money Market Fund

INVESTMENT OBJECTIVES

Janus Government Money Market Fund seeks capital preservation and liquidity with current income as a secondary objective.

FEES AND EXPENSES OF THE FUND

This table describes the fees and expenses that you may pay if you buy and hold Shares of the Fund.

ANNUAL FUND OPERATING EXPENSES
(expenses that you pay each year as a percentage of the value of your investment)

Annual Fund Operating Expenses	Janus Government Money Market Fund Class D Shares Class D
Operating Expenses Column [Text]	Class D
Management Fees	0.20%
Other Expenses	0.49%
Total Annual Fund Operating Expenses	0.69%

EXAMPLE:

The Example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds.

The Example assumes that you invest $10,000 in the Fund for the time periods indicated, reinvest all dividends and distributions, and then redeem all of your Shares at the end of each period. The Example also assumes that your investment has a 5% return each year and that the Fund’s operating expenses remain the same. Although your actual costs may be higher or lower, based on these assumptions your costs would be:

Expense Example (USD $)	Expense Example, By Year, Column [Text]	1 Year	3 Years	5 Years	10 Years
Janus Government Money Market Fund Class D Shares Class D	Class D Shares	70	221	384	859

PRINCIPAL INVESTMENT STRATEGIES

The Fund pursues its investment objectives by investing exclusively in obligations issued and/or guaranteed as to principal and interest by the United States Government or by its agencies and instrumentalities, and repurchase agreements secured by such obligations. Although U.S. Government agencies and instrumentalities may be chartered or sponsored by Acts of Congress, their securities are not issued by, and may not be guaranteed by (i.e., backed by the full faith and credit of), the United States Treasury. Some government agency and instrumentality securities not backed by the full faith and credit of the United States are supported by the issuer’s ability to borrow from the U.S. Treasury, some are supported only by the credit of the issuer, and some are supported by the United States in some other way. For securities not backed by the full faith and credit of the U.S. Treasury, the Fund must look principally to the agency or instrumentality issuing or guaranteeing the securities for repayment and may not be able to assert a claim against the United States if the agency or instrumentality does not meet its commitment. The Fund’s investments in securities issued by U.S. Government agencies and instrumentalities may be significant.

The Fund will:

• invest in high quality, short-term money market instruments that present minimal credit risks, as determined by Janus Capital

• invest only in U.S. dollar-denominated instruments that have a remaining maturity of 397 days or less (as calculated pursuant to Rule 2a-7 under the Investment Company Act of 1940, as amended)

• maintain a dollar-weighted average portfolio maturity of 60 days or less and maintain a dollar-weighted average portfolio life (portfolio maturity measured without reference to any maturity shortening provisions of adjustable rate securities by reference to their interest rate reset dates) of 120 days or less

PRINCIPAL INVESTMENT RISKS

Market Risk. The Fund’s yield will vary as the short-term securities in its portfolio mature and the proceeds are reinvested in securities with different interest rates. For capital preservation and liquidity, the Fund may have a greater concentration in short-term securities including, but not limited to, investing up to all of its assets in overnight securities, which may result in a reduction of the Fund’s yield. Over time, the real value of the Fund’s yield may be eroded by inflation. Although the Fund invests only in high-quality, short-term money market instruments, there is a risk that the value of the securities it holds will fall as a result of changes in interest rates, an issuer’s actual or perceived creditworthiness, or an issuer’s ability to meet its obligations. The credit quality of the Fund’s holdings can change rapidly in certain market environments and any downgrade or default of a portfolio security could cause the Fund’s share price or yield to fall.

Collateral Risk. With respect to collateral received in repurchase transactions or other investments, the Fund may have significant exposure to government agencies not secured by the full faith and credit of the United States. Such exposure, depending on market conditions, could have a negative impact on the Fund, including minimizing the value of any collateral.

Money Market Risk. An investment in the Fund is not a bank deposit and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency. Although the Fund seeks to preserve the value of your investment at $1.00 per share, it is possible to lose money by investing in the Fund.

PERFORMANCE INFORMATION

The following information provides some indication of the risks of investing in the Fund by showing how the Fund’s performance has varied over time. Class D Shares of the Fund commenced operations on February 16, 2010, as a result of the restructuring of Class J Shares, the predecessor share class. The performance shown for Class D Shares for periods prior to February 16, 2010, reflects the performance of the Fund’s former Class J Shares, calculated using the fees and expenses in effect during the periods shown, net of any applicable fee and expense limitations or waivers. If Class D Shares of the Fund had been available during periods prior to February 16, 2010, the performance shown may have been different. The performance shown for periods following the Fund’s commencement of Class D Shares reflects the fees and expenses of Class D Shares, net of any applicable fee and expense limitations or waivers.

The bar chart depicts the change in performance from year to year during the periods indicated. The table shows how the Fund’s returns over different periods average out. All figures assume reinvestment of dividends and distributions. For certain periods, the Fund’s performance reflects the effect of expense waivers. Without the effect of these expense waivers, the performance shown would have been lower.

The Fund’s past performance does not necessarily indicate how it will perform in the future. Updated performance information is available at janus.com/allfunds or by calling 1-800-525-3713.

Annual Total Returns for Class D Shares (calendar year-end)

Best Quarter:  Fourth Quarter 2006  1.21%          Worst Quarter:  Third Quarter 2011  0.00%

The Fund’s year-to-date return as of the calendar quarter ended September 30, 2013 was 0.00%.

Average Annual Total Returns (periods ended 12/31/12)

Average Annual Total Returns	Column	Label	1 Year	5 Years	10 Years	Since Inception	Inception Date
Janus Government Money Market Fund Class D Shares Class D Return Before Taxes	Class D Shares	Return Before Taxes	none	0.37%	1.51%	2.82%	Feb. 14, 1995

The 7-day yield on December 31, 2012 was 0.01% for Janus Government Money Market Fund.

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Perkins Value Plus Income Fund | Class D Shares

FUND SUMMARY

Perkins Value Plus Income Fund

INVESTMENT OBJECTIVE

Perkins Value Plus Income Fund seeks capital appreciation and current income.

FEES AND EXPENSES OF THE FUND

This table describes the fees and expenses that you may pay if you buy and hold Shares of the Fund.

ANNUAL FUND OPERATING EXPENSES
(expenses that you pay each year as a percentage of the value of your investment)

Annual Fund Operating Expenses		Perkins Value Plus Income Fund Class D Shares Class D
Operating Expenses Column [Text]		Class D
Management Fees		0.60%
Other Expenses		0.64%
Total Annual Fund Operating Expenses	[1]	1.24%
Fee Waiver	[1]	0.43%
Total Annual Fund Operating Expenses After Fee Waiver	[1]	0.81%

EXAMPLE:

The following Example is based on expenses without waivers. The Example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds.

The Example assumes that you invest $10,000 in the Fund for the time periods indicated, reinvest all dividends and distributions, and then redeem all of your Shares at the end of each period. The Example also assumes that your investment has a 5% return each year and that the Fund’s operating expenses without waivers or recoupments (if applicable) remain the same. Although your actual costs may be higher or lower, based on these assumptions your costs would be:

Expense Example (USD $)	Expense Example, By Year, Column [Text]	1 Year	3 Years	5 Years	10 Years
Perkins Value Plus Income Fund Class D Shares Class D	Class D Shares	126	393	681	1,500

Portfolio Turnover:

The Fund pays transaction costs, such as commissions, when it buys and sells securities (or “turns over” its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when Fund shares are held in a taxable account. These costs, which are not reflected in annual fund operating expenses or in the Example, affect the Fund’s performance. During the most recent fiscal year, the Fund’s portfolio turnover rate was 97% of the average value of its portfolio.

PRINCIPAL INVESTMENT STRATEGIES

The Fund pursues its investment objective by normally investing 40-60% of its assets in equity securities selected primarily for capital appreciation and investing the remainder in fixed-income securities and cash equivalents.

Equity Securities. The Fund’s equity investments generate total return from a combination of capital appreciation and, to a lesser degree, current income. Such equity investments may include companies of any size, but the Fund will invest primarily in large- and mid-sized companies whose stock prices the portfolio managers believe to be undervalued or have the potential for high relative dividend yields, or both. The Fund’s equity portfolio managers invest in companies which have fallen out of favor with the market or that appear to be temporarily misunderstood by the investment community. The Fund’s equity portfolio managers generally look for companies with:

• strong balance sheets and solid recurring free cash flows
• attractive relative and absolute valuation ratios or that have underperformed recently
• favorable reward to risk characteristics

Fixed-Income Securities. The Fund’s fixed-income investments generate total return from a combination of current income and capital appreciation, but income is usually the dominant portion. The Fund normally invests the portion of its assets allocated to fixed-income investments in debt securities (including, but not limited to, government bonds, corporate bonds, mortgage-backed securities, asset-backed securities, zero-coupon bonds, and bank loans), convertible securities, and short-term securities. The Fund invests at least 50% of the fixed-income portion of its assets in investment grade debt securities. The Fund will limit its investment in high-yield/high-risk bonds, also known as “junk” bonds, to 50% or less of the fixed-income portion of its net assets.

In addition to considering economic factors such as the effect of interest rates on the Fund’s fixed-income investments, the Fund’s fixed-income portfolio managers apply a “bottom up” approach in choosing investments. This means that the portfolio managers look at income-producing securities one at a time to determine if a security is an attractive investment opportunity and if it is consistent with the Fund’s investment policies.

The Fund may also invest in foreign equity and debt securities, which may include investments in emerging markets.

The Fund may also invest its assets in derivatives, which are instruments that have a value derived from, or directly linked to, an underlying asset, such as equity securities, fixed-income securities, commodities, currencies, interest rates, or market indices. The Fund has and is expected to continue to buy and sell put and call options to enhance returns. The Fund’s exposure to derivatives will vary, is not limited to those derivatives listed, and could be significant at times.

Janus Capital is primarily responsible for the overall asset allocation of the Fund and manages the Fund’s fixed-income investments. Cash positions are considered a part of the Fund’s fixed-income allocation and will be managed by the Fund’s fixed-income portfolio managers. Perkins manages the Fund’s equity investments and assists the adviser in determining the Fund’s overall asset allocation. The Fund may periodically adjust its mix of equity and fixed-income investments in response to changing economic and market conditions, including outside the range of 40-60% of its assets in equity securities. Due to the nature of the fixed-income securities in which the Fund invests, it may have relatively high portfolio turnover compared to other funds.

The Fund’s fixed-income portfolio managers may lend portfolio securities on a short-term or long-term basis, in an amount equal to up to 1/3 of its total assets as determined at the time of the loan origination.

PRINCIPAL INVESTMENT RISKS

The biggest risk is that the Fund’s returns and yields will vary, and you could lose money. The Fund is designed for long-term investors seeking a portfolio including common stocks and bonds selected for their potential to produce capital appreciation and current income. Common stocks tend to be more volatile than many other investment choices.

Market Risk. The value of the Fund’s portfolio may decrease if the value of an individual company or security, or multiple companies or securities, in the portfolio decreases or if the portfolio managers’ belief about a company’s intrinsic worth is incorrect. Further, regardless of how well individual companies or securities perform, the value of the Fund’s portfolio could also decrease if there are deteriorating economic or market conditions. It is important to understand that the value of your investment may fall, sometimes sharply, in response to changes in the market, and you could lose money.

Value Investing Risk. Because different types of stocks tend to shift in and out of favor depending on market and economic conditions, “value” stocks may perform differently than other types of stocks and from the market as a whole, and can continue to be undervalued by the market for long periods of time. It is also possible that a value stock will never appreciate to the extent expected by the equity portfolio managers.

Mid-Sized Companies Risk. The Fund’s investments in securities issued by mid-sized companies may involve greater risks than are customarily associated with larger, more established companies. Securities issued by mid-sized companies tend to be more volatile than securities issued by larger or more established companies and may underperform as compared to the securities of larger companies.

Fixed-Income Securities Risk. The Fund invests in a variety of fixed-income securities. Typically, the values of fixed-income securities change inversely with prevailing interest rates. Therefore, a fundamental risk of fixed-income securities is interest rate risk, which is the risk that the value of such securities will generally decline as prevailing interest rates rise, which may cause the Fund’s net asset value to likewise decrease. How specific fixed-income securities may react to changes in interest rates will depend on the specific characteristics of each security. Fixed-income securities are also subject to credit risk, prepayment risk, valuation risk, and liquidity risk. Credit risk is the risk that the credit strength of an issuer of a fixed-income security will weaken and/or that the issuer will be unable to make timely principal and interest payments and that the security may go into default. Prepayment risk is the risk that during periods of falling interest rates, certain fixed-income securities with higher interest rates, such as mortgage- and asset-backed securities, may be prepaid by their issuers thereby reducing the amount of interest payments. Valuation risk is the risk that one or more of the fixed-income securities in which the Fund invests are priced differently than the value realized upon such security’s sale. In times of market instability, valuation may be more difficult. Liquidity risk is the risk that fixed-income securities may be difficult or impossible to sell at the time that the portfolio managers would like or at the price the portfolio managers believe the security is currently worth.

Mortgage-Backed Securities Risk. Mortgage-backed securities are classified generally as either commercial mortgage-backed securities or residential mortgage-backed securities, each of which is subject to certain specific risks. Mortgage-backed securities tend to be more sensitive to changes in interest rates than other types of debt securities. Investments in mortgage-backed securities are subject to both extension risk, where borrowers extend the duration of their mortgages in times of rising interest rates, and prepayment risk, where borrowers pay off their mortgages sooner than expected in times of declining interest rates. These risks may reduce the Fund’s returns. In addition, investments in mortgage-backed securities, including those comprised of subprime mortgages, may be subject to a higher degree of credit risk, valuation risk, and liquidity risk than various other types of fixed-income securities.

High-Yield/High-Risk Bond Risk. High-yield/high-risk bonds may be more sensitive than other types of bonds to economic changes, political changes, or adverse developments specific to the company that issued the bond, which may adversely affect their value.

Bank Loan Risk. Bank loans are obligations of companies or other entities entered into in connection with recapitalizations, acquisitions, and refinancings. The Fund’s investments in bank loans are generally acquired as a participation interest in, or assignment of, loans originated by a lender or other financial institution. These investments may include institutionally-traded floating and fixed-rate debt securities. Participation interests and assignments involve credit, interest rate, and liquidity risk. In addition, the bank loans underlying these securities often involve borrowers with low credit ratings whose financial conditions are troubled or uncertain, including companies that are highly leveraged or in bankruptcy proceedings.

Foreign Exposure Risk. The Fund may have exposure to foreign markets as a result of its investments in foreign securities, including investments in emerging markets, which can be more volatile than the U.S. markets. As a result, its returns and net asset value may be affected to a large degree by fluctuations in currency exchange rates or political or economic conditions in a particular country. In some foreign markets, there may not be protection against failure by other parties to complete transactions. It may not be possible for the Fund to repatriate capital, dividends, interest, and other income from a particular country or governmental entity. In addition, a market swing in one or more countries or regions where the Fund has invested a significant amount of its assets may have a greater effect on the Fund’s performance than it would in a more geographically diversified portfolio. To the extent the Fund invests in foreign debt securities, such investments are sensitive to changes in interest rates. Additionally, investments in securities of foreign governments involve the risk that a foreign government may not be willing or able to pay interest or repay principal when due. The Fund’s investments in emerging market countries may involve risks greater than, or in addition to, the risks of investing in more developed countries.

Eurozone Risk. A number of countries in the European Union (“EU”) have experienced severe economic and financial difficulties. As a result, financial markets in the EU have been subject to extreme volatility and declines in asset values and liquidity. Responses to these financial problems by European governments, central banks, and others, including austerity measures and reforms, may not work, may result in social unrest, and may limit future growth and economic recovery or have other unintended consequences. Further defaults or restructurings by governments and others of their debt could have additional adverse effects on economies, financial markets, and asset valuations around the world. To the extent that the Fund has exposure to European markets or to transactions tied to the value of the euro, these events could negatively affect the value and liquidity of the Fund’s investments.

Sovereign Debt Risk. The Fund may invest in U.S. and foreign government debt securities (“sovereign debt”). Investments in U.S. sovereign debt are considered low risk. However, investments in non-U.S. sovereign debt can involve a high degree of risk, including the risk that the governmental entity that controls the repayment of sovereign debt may not be willing or able to repay the principal and/or to pay the interest on its sovereign debt in a timely manner. A sovereign debtor’s willingness or ability to satisfy its debt obligation may be affected by various factors including, but not limited to, its cash flow situation, the extent of its foreign currency reserves, the availability of foreign exchange when a payment is due, and the relative size of its debt position in relation to its economy as a whole. In the event of default, there may be limited or no legal remedies for collecting sovereign debt and there may be no bankruptcy proceedings through which the Fund may collect all or part of the sovereign debt that a governmental entity has not repaid.

Real Estate Securities Risk. The Fund’s performance may be affected by the risks associated with investments in real estate-related companies. The value of real estate-related companies’ securities is sensitive to changes in real estate values and rental income, property taxes, interest rates, tax and regulatory requirements, supply and demand, and the management skill and creditworthiness of the company. Investments in real estate investment trusts (“REITs”) involve the same risks as other real estate investments. In addition, a REIT could fail to qualify for tax-free pass-through of its income under the Internal Revenue Code or fail to maintain its exemption from registration under the Investment Company Act of 1940, as amended, which could produce adverse economic consequences for the REIT and its investors, including the Fund.

Derivatives Risk. Derivatives can be highly volatile and involve risks in addition to the risks of the underlying referenced securities. Gains or losses from a derivative investment can be substantially greater than the derivative’s original cost, and can therefore involve leverage. Leverage may cause the Fund to be more volatile than if it had not used leverage. Derivatives can be complex instruments and may involve analysis that differs from that required for other investment types used by the Fund. If the value of a derivative does not correlate well with the particular market or other asset class to which the derivative is intended to provide exposure, the derivative may not produce the anticipated result. Derivatives can also reduce the opportunity for gain or result in losses by offsetting positive returns in other investments. Derivatives can be less liquid than other types of investments and entail the risk that the counterparty will default on its payment obligations. If the counterparty to a derivative transaction defaults, the Fund would risk the loss of the net amount of the payments that it contractually is entitled to receive. To the extent the Fund enters into short derivative positions, the Fund may be exposed to risks similar to those associated with short sales, including the risk that the Fund’s losses are theoretically unlimited.

Allocation Risk. The Fund’s ability to achieve its investment objective depends largely upon the allocation of assets among the equity and fixed asset categories. You could lose money on your investment in the Fund as a result of these allocations. Portfolio management may favor an asset category that underperforms relative to other asset categories. For example, the Fund may be overweighted in equity securities when the stock market is falling and the fixed-income market is rising. Additionally, periodic rebalancing of Fund assets among asset categories may result in increased transaction costs, which may have a negative effect on the Fund’s performance.

Portfolio Turnover Risk. Increased portfolio turnover may result in higher costs, which may have a negative effect on the Fund’s performance. In addition, higher portfolio turnover may result in the acceleration of capital gains and the recognition of greater levels of short-term capital gains, which are taxed at ordinary federal income tax rates when distributed to shareholders.

Securities Lending Risk. The Fund’s fixed-income portfolio managers may seek to earn additional income through lending its securities to certain qualified broker-dealers and institutions. There is the risk that when portfolio securities are lent, the securities may not be returned on a timely basis, and the Fund may experience delays and costs in recovering the security or gaining access to the collateral provided to the Fund to collateralize the loan. If the Fund is unable to recover a security on loan, the Fund may use the collateral to purchase replacement securities in the market. There is a risk that the value of the collateral could decrease below the cost of the replacement security by the time the replacement investment is made, resulting in a loss to the Fund.

An investment in the Fund is not a bank deposit and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency.

PERFORMANCE INFORMATION

The following information provides some indication of the risks of investing in the Fund by showing how the Fund’s performance has varied over time. The bar chart depicts the change in performance from year to year during the periods indicated. The table compares the Fund’s average annual returns for the periods indicated to broad-based securities market indices. The indices are not actively managed and are not available for direct investment. All figures assume reinvestment of dividends and distributions. For certain periods, the Fund’s performance reflects the effect of expense waivers. Without the effect of these expense waivers, the performance shown would have been lower.

The Fund’s past performance (before and after taxes) does not necessarily indicate how it will perform in the future. Updated performance information is available at janus.com/allfunds or by calling 1-800-525-3713.

Annual Total Returns for Class D Shares (calendar year-end)

Best Quarter:  Fourth Quarter 2011  7.30%          Worst Quarter:  Third Quarter 2011  −7.84%

The Fund’s year-to-date return as of the calendar quarter ended September 30, 2013 was 8.96%.

Average Annual Total Returns (periods ended 12/31/12)

Average Annual Total Returns Perkins Value Plus Income Fund Class D Shares	Column	Label	1 Year	Since Inception	Inception Date
Class D Return Before Taxes	Class D Shares	Return Before Taxes	11.56%	10.17%	Jul. 30, 2010
Class D Return After Taxes on Distributions	Class D Shares	Return After Taxes on Distributions	10.15%	8.52%	Jul. 30, 2010
Class D Return After Taxes on Distributions and Sale of Fund Shares	Class D Shares	Return After Taxes on Distributions and Sale of Fund Shares	8.07%	7.90%	Jul. 30, 2010
Russell 1000® Value Index (reflects no deduction for expenses, fees, or taxes)		Russell 1000® Value Index	17.51%	13.02%	Jul. 30, 2010
Barclays U.S. Aggregate Bond Index (reflects no deduction for expenses, fees, or taxes)		Barclays U.S. Aggregate Bond Index	4.21%	4.97%	Jul. 30, 2010
Value Income Index (reflects no deduction for expenses, fees, or taxes)		Value Income Index	10.84%	9.26%	Jul. 30, 2010

The Value Income Index is an internally-calculated, hypothetical combination of unmanaged indices that combines total returns from the Russell 1000^® Value Index (50%) and the Barclays U.S. Aggregate Bond Index (50%).

After-tax returns are calculated using the historically highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes. Actual after-tax returns depend on your individual tax situation and may differ from those shown in the preceding table. The after-tax return information shown above does not apply to Fund shares held through a tax-deferred account, such as a 401(k) plan or an IRA.

[1] Janus Capital has contractually agreed to waive its investment advisory fee and/or reimburse Fund expenses to the extent that the Fund’s total annual fund operating expenses (excluding administrative services fees payable pursuant to the Transfer Agency Agreement, brokerage commissions, interest, dividends, taxes, acquired fund fees and expenses, and extraordinary expenses) exceed 0.68% until at least November 1, 2014. The contractual waiver may be terminated or modified prior to this date only at the discretion of the Board of Trustees. For a period of three years subsequent to the Fund’s commencement of operations (July 30, 2010), Janus Capital may recover from the Fund fees and expenses previously waived or reimbursed, which could then be considered a deferral, if the Fund’s expense ratio, including recovered expenses, falls below the expense limit.

XML

Label	Element	Value
Risk/Return:	rr_RiskReturnAbstract
Registrant Name	dei_EntityRegistrantName	JANUS INVESTMENT FUND
Prospectus Date	rr_ProspectusDate	Oct. 28, 2013
Perkins Select Value Fund | Class D Shares
Risk/Return:	rr_RiskReturnAbstract
Risk/Return [Heading]	rr_RiskReturnHeading	FUND SUMMARY Perkins Select Value Fund
Objective [Heading]	rr_ObjectiveHeading	INVESTMENT OBJECTIVE
Objective, Primary [Text Block]	rr_ObjectivePrimaryTextBlock	Perkins Select Value Fund seeks capital appreciation.
Expense [Heading]	rr_ExpenseHeading	FEES AND EXPENSES OF THE FUND
Expense Narrative [Text Block]	rr_ExpenseNarrativeTextBlock	This table describes the fees and expenses that you may pay if you buy and hold Shares of the Fund.
Operating Expenses Caption [Text]	rr_OperatingExpensesCaption	ANNUAL FUND OPERATING EXPENSES (expenses that you pay each year as a percentage of the value of your investment)
Fee Waiver or Reimbursement over Assets, Date of Termination	rr_FeeWaiverOrReimbursementOverAssetsDateOfTermination	November 1, 2014
Portfolio Turnover [Heading]	rr_PortfolioTurnoverHeading	Portfolio Turnover:
Portfolio Turnover [Text Block]	rr_PortfolioTurnoverTextBlock	The Fund pays transaction costs, such as commissions, when it buys and sells securities (or “turns over” its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when Fund shares are held in a taxable account. These costs, which are not reflected in annual fund operating expenses or in the Example, affect the Fund’s performance. During the most recent fiscal year, the Fund’s portfolio turnover rate was 62% of the average value of its portfolio.
Portfolio Turnover, Rate	rr_PortfolioTurnoverRate	62.00%
Expense Example [Heading]	rr_ExpenseExampleHeading	EXAMPLE:
Expense Example by Year [Heading]	rr_ExpenseExampleByYearHeading	The Example assumes that you invest $10,000 in the Fund for the time periods indicated, reinvest all dividends and distributions, and then redeem all of your Shares at the end of each period. The Example also assumes that your investment has a 5% return each year and that the Fund’s operating expenses without waivers remain the same. Although your actual costs may be higher or lower, based on these assumptions your costs would be:
Expense Example Narrative [Text Block]	rr_ExpenseExampleNarrativeTextBlock	The following Example is based on expenses without waivers. The Example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds.
Strategy [Heading]	rr_StrategyHeading	PRINCIPAL INVESTMENT STRATEGIES
Strategy Narrative [Text Block]	rr_StrategyNarrativeTextBlock	The Fund pursues its investment objective by investing primarily in common stocks in all capitalization ranges selected for their capital appreciation potential. The Fund primarily invests in the common stocks of companies of any size whose stock prices the portfolio managers believe to be undervalued. The Fund may also invest in foreign equity and debt securities, which may include investments in emerging markets. In addition, when the portfolio managers believe that market conditions are unfavorable for investing, or when they are otherwise unable to locate attractive investment opportunities, the Fund’s cash or similar investments may increase. The Fund focuses on companies that have fallen out of favor with the market or that appear to be temporarily misunderstood by the investment community. The Fund’s portfolio managers generally look for companies with: strong balance sheets and solid recurring free cash flows attractive relative and absolute valuation ratios or that have underperformed recently favorable reward to risk characteristics The Fund may invest its assets in derivatives, which are instruments that have a value derived from, or directly linked to, an underlying asset, such as equity securities, fixed-income securities, commodities, currencies, interest rates, or market indices, as substitutes for securities in which the Fund invests. The Fund may invest in derivative instruments (by taking long and/or short positions) for different purposes, including hedging (to offset risks associated with an investment, currency exposure, or market conditions) and to earn income and enhance returns.
Risk [Heading]	rr_RiskHeading	PRINCIPAL INVESTMENT RISKS
Risk Narrative [Text Block]	rr_RiskNarrativeTextBlock	The biggest risk is that the Fund’s returns will vary, and you could lose money. The Fund is designed for long-term investors seeking an equity portfolio, including common stocks. Common stocks tend to be more volatile than many other investment choices. Value Investing Risk. Because different types of stocks tend to shift in and out of favor depending on market and economic conditions, “value” stocks may perform differently than other types of stocks and from the market as a whole, and can continue to be undervalued by the market for long periods of time. It is also possible that a value stock will never appreciate to the extent expected by the portfolio managers. When the Fund’s investments in cash or similar investments increase due to a lack of favorable investment opportunities or other extraordinary factors, the Fund may not participate in market advances or declines to the same extent that it would if the Fund had been fully invested. Market Risk. The value of the Fund’s portfolio may decrease if the value of an individual company or security, or multiple companies or securities, in the portfolio decreases or if the portfolio managers’ belief about a company’s intrinsic worth is incorrect. Further, regardless of how well individual companies or securities perform, the value of the Fund’s portfolio could also decrease if there are deteriorating economic or market conditions. It is important to understand that the value of your investment may fall, sometimes sharply, in response to changes in the market, and you could lose money. Foreign Exposure Risk. The Fund may have significant exposure to foreign markets as a result of its investments in foreign securities, including investments in emerging markets, which can be more volatile than the U.S. markets. As a result, its returns and net asset value may be affected to a large degree by fluctuations in currency exchange rates or political or economic conditions in a particular country. In some foreign markets, there may not be protection against failure by other parties to complete transactions. It may not be possible for the Fund to repatriate capital, dividends, interest, and other income from a particular country or governmental entity. In addition, a market swing in one or more countries or regions where the Fund has invested a significant amount of its assets may have a greater effect on the Fund’s performance than it would in a more geographically diversified portfolio. To the extent the Fund invests in foreign debt securities, such investments are sensitive to changes in interest rates. Additionally, investments in securities of foreign governments involve the risk that a foreign government may not be willing or able to pay interest or repay principal when due. Eurozone Risk. A number of countries in the European Union (“EU”) have experienced severe economic and financial difficulties. As a result, financial markets in the EU have been subject to extreme volatility and declines in asset values and liquidity. Responses to these financial problems by European governments, central banks, and others, including austerity measures and reforms, may not work, may result in social unrest, and may limit future growth and economic recovery or have other unintended consequences. Further defaults or restructurings by governments and others of their debt could have additional adverse effects on economies, financial markets, and asset valuations around the world. To the extent that the Fund has exposure to European markets or to transactions tied to the value of the euro, these events could negatively affect the value and liquidity of the Fund’s investments. Real Estate Securities Risk. The Fund’s performance may be affected by the risks associated with investments in real estate-related companies. The value of real estate-related companies’ securities is sensitive to changes in real estate values and rental income, property taxes, interest rates, tax and regulatory requirements, supply and demand, and the management skill and creditworthiness of the company. Investments in real estate investment trusts (“REITs”) involve the same risks as other real estate investments. In addition, a REIT could fail to qualify for tax-free pass-through of its income under the Internal Revenue Code or fail to maintain its exemption from registration under the Investment Company Act of 1940, as amended, which could produce adverse economic consequences for the REIT and its investors, including the Fund. Derivatives Risk. Derivatives can be highly volatile and involve risks in addition to the risks of the underlying referenced securities. Gains or losses from a derivative investment can be substantially greater than the derivative’s original cost, and can therefore involve leverage. Leverage may cause the Fund to be more volatile than if it had not used leverage. Derivatives can be less liquid than other types of investments and entail the risk that the counterparty will default on its payment obligations. An investment in the Fund is not a bank deposit and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency.
Risk Lose Money [Text]	rr_RiskLoseMoney	The biggest risk is that the Fund’s returns will vary, and you could lose money.
Risk Not Insured Depository Institution [Text]	rr_RiskNotInsuredDepositoryInstitution	An investment in the Fund is not a bank deposit and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency.
Bar Chart and Performance Table [Heading]	rr_BarChartAndPerformanceTableHeading	PERFORMANCE INFORMATION
Performance Narrative [Text Block]	rr_PerformanceNarrativeTextBlock	The following information provides some indication of the risks of investing in the Fund by showing how the Fund’s performance has varied over time. The bar chart depicts the Fund’s performance during the period indicated. The table compares the Fund’s average annual returns for the periods indicated to a broad-based securities market index. The index is not actively managed and is not available for direct investment. All figures assume reinvestment of dividends and distributions. For certain periods, the Fund’s performance reflects the effect of expense waivers. Without the effect of these expense waivers, the performance shown would have been lower. The Fund’s past performance (before and after taxes) does not necessarily indicate how it will perform in the future. Updated performance information is available at janus.com/allfunds or by calling 1-800-525-3713.
Performance Information Illustrates Variability of Returns [Text]	rr_PerformanceInformationIllustratesVariabilityOfReturns	The following information provides some indication of the risks of investing in the Fund by showing how the Fund’s performance has varied over time. The bar chart depicts the Fund’s performance during the period indicated.
Performance Additional Market Index [Text]	rr_PerformanceAdditionalMarketIndex	The table compares the Fund’s average annual returns for the periods indicated to a broad-based securities market index. The index is not actively managed and is not available for direct investment. All figures assume reinvestment of dividends and distributions.
Performance Availability Phone [Text]	rr_PerformanceAvailabilityPhone	1-800-525-3713
Performance Availability Website Address [Text]	rr_PerformanceAvailabilityWebSiteAddress	janus.com/allfunds
Performance Past Does Not Indicate Future [Text]	rr_PerformancePastDoesNotIndicateFuture	The Fund’s past performance (before and after taxes) does not necessarily indicate how it will perform in the future.
Bar Chart [Heading]	rr_BarChartHeading	Annual Total Returns for Class D Shares (calendar year-end)
Bar Chart Closing [Text Block]	rr_BarChartClosingTextBlock	Best Quarter:  First Quarter 2012  11.14%          Worst Quarter:  Second Quarter 2012  −4.75%
Year to Date Return, Label	rr_YearToDateReturnLabel	The Fund’s year-to-date return as of the calendar quarter ended September 30, 2013 was 15.49%.
Performance Table Heading	rr_PerformanceTableHeading	Average Annual Total Returns (periods ended 12/31/12)
Performance Table Uses Highest Federal Rate	rr_PerformanceTableUsesHighestFederalRate	After-tax returns are calculated using the historically highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes.
Performance Table Not Relevant to Tax Deferred	rr_PerformanceTableNotRelevantToTaxDeferred	Actual after-tax returns depend on your individual tax situation and may differ from those shown in the preceding table. The after-tax return information shown above does not apply to Fund shares held through a tax-deferred account, such as a 401(k) plan or an IRA.
Performance Table Narrative	rr_PerformanceTableNarrativeTextBlock	The Russell 3000® Value Index measures the performance of those Russell 3000® companies with lower price-to-book ratios and lower forecasted growth values. The stocks in the Russell 3000® Value Index are also members of either the Russell 1000® Value Index or the Russell 2000® Value Index. This index is used to calculate the performance fee adjustment. After-tax returns are calculated using the historically highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes. Actual after-tax returns depend on your individual tax situation and may differ from those shown in the preceding table. The after-tax return information shown above does not apply to Fund shares held through a tax-deferred account, such as a 401(k) plan or an IRA.
Performance Table Closing [Text Block]	rr_PerformanceTableClosingTextBlock	Updated performance information is available at janus.com/allfunds or by calling 1-800-525-3713.
Perkins Select Value Fund | Class D Shares | Class D
Risk/Return:	rr_RiskReturnAbstract
Operating Expenses Column [Text]	rr_OperatingExpensesColumnName	Class D
Management Fees (may adjust up or down)	rr_ManagementFeesOverAssets	0.63%
Other Expenses	rr_OtherExpensesOverAssets	0.38%
Total Annual Fund Operating Expenses	rr_ExpensesOverAssets	1.01%	[1]
Fee Waiver	rr_FeeWaiverOrReimbursementOverAssets	0.19%	[1]
Total Annual Fund Operating Expenses After Fee Waiver	rr_NetExpensesOverAssets	0.82%	[1]
Expense Example, By Year, Column [Text]	rr_ExpenseExampleByYearColumnName	Class D Shares
1 Year	rr_ExpenseExampleYear01	$ 103
3 Years	rr_ExpenseExampleYear03	322
5 Years	rr_ExpenseExampleYear05	558
10 Years	rr_ExpenseExampleYear10	$ 1,236
2012	rr_AnnualReturn2012	12.30%
Bar Chart, Year to Date Return, Date	rr_BarChartYearToDateReturnDate	Sep. 30, 2013
Bar Chart, Year to Date Return	rr_BarChartYearToDateReturn	15.49%
Highest Quarterly Return, Label	rr_HighestQuarterlyReturnLabel	Best Quarter:
Highest Quarterly Return, Date	rr_BarChartHighestQuarterlyReturnDate	Mar. 31, 2012
Highest Quarterly Return	rr_BarChartHighestQuarterlyReturn	11.14%
Lowest Quarterly Return, Label	rr_LowestQuarterlyReturnLabel	Worst Quarter:
Lowest Quarterly Return, Date	rr_BarChartLowestQuarterlyReturnDate	Jun. 30, 2012
Lowest Quarterly Return	rr_BarChartLowestQuarterlyReturn	(4.75%)
Perkins Select Value Fund | Class D Shares | Return Before Taxes | Class D
Risk/Return:	rr_RiskReturnAbstract
Column	rr_AverageAnnualReturnColumnName	Class D Shares
Label	rr_AverageAnnualReturnLabel	Return Before Taxes
1 Year	rr_AverageAnnualReturnYear01	12.30%
Since Inception	rr_AverageAnnualReturnSinceInception	14.22%
Inception Date	rr_AverageAnnualReturnInceptionDate	Dec. 15, 2011
Perkins Select Value Fund | Class D Shares | Return After Taxes on Distributions | Class D
Risk/Return:	rr_RiskReturnAbstract
Column	rr_AverageAnnualReturnColumnName	Class D Shares
Label	rr_AverageAnnualReturnLabel	Return After Taxes on Distributions
1 Year	rr_AverageAnnualReturnYear01	9.60%
Since Inception	rr_AverageAnnualReturnSinceInception	11.58%
Inception Date	rr_AverageAnnualReturnInceptionDate	Dec. 15, 2011
Perkins Select Value Fund | Class D Shares | Return After Taxes on Distributions and Sale of Fund Shares | Class D
Risk/Return:	rr_RiskReturnAbstract
Column	rr_AverageAnnualReturnColumnName	Class D Shares
Label	rr_AverageAnnualReturnLabel	Return After Taxes on Distributions and Sale of Fund Shares
1 Year	rr_AverageAnnualReturnYear01	8.18%
Since Inception	rr_AverageAnnualReturnSinceInception	10.66%
Inception Date	rr_AverageAnnualReturnInceptionDate	Dec. 15, 2011
Perkins Select Value Fund | Class D Shares | Russell 3000® Value Index (reflects no deduction for expenses, fees, or taxes)
Risk/Return:	rr_RiskReturnAbstract
Label	rr_AverageAnnualReturnLabel	Russell 3000® Value Index
1 Year	rr_AverageAnnualReturnYear01	17.55%
Since Inception	rr_AverageAnnualReturnSinceInception	21.33%
Inception Date	rr_AverageAnnualReturnInceptionDate	Dec. 15, 2011

[1] Janus Capital has contractually agreed to waive its investment advisory fee and/or reimburse Fund expenses to the extent that the Fund’s total annual fund operating expenses (excluding any performance adjustments to management fees, administrative services fees payable pursuant to the Transfer Agency Agreement, brokerage commissions, interest, dividends, taxes, acquired fund fees and expenses, and extraordinary expenses) exceed 0.77% until at least November 1, 2014. The contractual waiver may be terminated or modified prior to this date only at the discretion of the Board of Trustees.

XML

Label	Element	Value
Risk/Return:	rr_RiskReturnAbstract
Registrant Name	dei_EntityRegistrantName	JANUS INVESTMENT FUND
Prospectus Date	rr_ProspectusDate	Oct. 28, 2013
Perkins Value Plus Income Fund | Class A, C, S, I, N, T Shares
Risk/Return:	rr_RiskReturnAbstract
Risk/Return [Heading]	rr_RiskReturnHeading	FUND SUMMARY Perkins Value Plus Income Fund
Objective [Heading]	rr_ObjectiveHeading	INVESTMENT OBJECTIVE
Objective, Primary [Text Block]	rr_ObjectivePrimaryTextBlock	Perkins Value Plus Income Fund seeks capital appreciation and current income.
Expense [Heading]	rr_ExpenseHeading	FEES AND EXPENSES OF THE FUND
Expense Narrative [Text Block]	rr_ExpenseNarrativeTextBlock	This table describes the fees and expenses that you may pay if you buy and hold Shares of the Fund. Each share class has different expenses, but represents an investment in the same Fund.
Shareholder Fees Caption [Text]	rr_ShareholderFeesCaption	SHAREHOLDER FEES (fees paid directly from your investment)
Operating Expenses Caption [Text]	rr_OperatingExpensesCaption	ANNUAL FUND OPERATING EXPENSES (expenses that you pay each year as a percentage of the value of your investment)
Fee Waiver or Reimbursement over Assets, Date of Termination	rr_FeeWaiverOrReimbursementOverAssetsDateOfTermination	November 1, 2014
Portfolio Turnover [Heading]	rr_PortfolioTurnoverHeading	Portfolio Turnover:
Portfolio Turnover [Text Block]	rr_PortfolioTurnoverTextBlock	The Fund pays transaction costs, such as commissions, when it buys and sells securities (or “turns over” its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when Fund shares are held in a taxable account. These costs, which are not reflected in annual fund operating expenses or in the Example, affect the Fund’s performance. During the most recent fiscal year, the Fund’s portfolio turnover rate was 97% of the average value of its portfolio.
Portfolio Turnover, Rate	rr_PortfolioTurnoverRate	97.00%
Expense Breakpoint Discounts [Text]	rr_ExpenseBreakpointDiscounts	For Class A Shares, you may qualify for sales charge discounts if you and your family invest, or agree to invest in the future, at least $50,000 in the Fund or in other Janus mutual funds. More information about these and other discounts, as well as eligibility requirements for each share class, is available from your financial professional and in the “Purchases” section on page 66 of the Fund’s Prospectus and in the “Purchases” section on page 70 of the Fund’s Statement of Additional Information.
Expense Breakpoint, Minimum Investment Required [Amount]	rr_ExpenseBreakpointMinimumInvestmentRequiredAmount	$ 50,000
Expense Example [Heading]	rr_ExpenseExampleHeading	EXAMPLE:
Expense Example by Year [Heading]	rr_ExpenseExampleByYearHeading	The Example assumes that you invest $10,000 in the Fund for the time periods indicated and reinvest all dividends and distributions. The Example also assumes that your investment has a 5% return each year and that the Fund’s operating expenses without waivers or recoupments (if applicable) remain the same. Although your actual costs may be higher or lower, based on these assumptions your costs would be:
Expense Example Narrative [Text Block]	rr_ExpenseExampleNarrativeTextBlock	The following Example is based on expenses without waivers. The Example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds.
Expense Example by, Year, Caption [Text]	rr_ExpenseExampleByYearCaption	If Shares are redeemed:
Expense Example, No Redemption, By Year, Caption [Text]	rr_ExpenseExampleNoRedemptionByYearCaption	If Shares are not redeemed:
Strategy [Heading]	rr_StrategyHeading	PRINCIPAL INVESTMENT STRATEGIES
Strategy Narrative [Text Block]	rr_StrategyNarrativeTextBlock	The Fund pursues its investment objective by normally investing 40-60% of its assets in equity securities selected primarily for capital appreciation and investing the remainder in fixed-income securities and cash equivalents. Equity Securities. The Fund’s equity investments generate total return from a combination of capital appreciation and, to a lesser degree, current income. Such equity investments may include companies of any size, but the Fund will invest primarily in large- and mid-sized companies whose stock prices the portfolio managers believe to be undervalued or have the potential for high relative dividend yields, or both. The Fund’s equity portfolio managers invest in companies which have fallen out of favor with the market or that appear to be temporarily misunderstood by the investment community. The Fund’s equity portfolio managers generally look for companies with: strong balance sheets and solid recurring free cash flows attractive relative and absolute valuation ratios or that have underperformed recently favorable reward to risk characteristics Fixed-Income Securities. The Fund’s fixed-income investments generate total return from a combination of current income and capital appreciation, but income is usually the dominant portion. The Fund normally invests the portion of its assets allocated to fixed-income investments in debt securities (including, but not limited to, government bonds, corporate bonds, mortgage-backed securities, asset-backed securities, zero-coupon bonds, and bank loans), convertible securities, and short-term securities. The Fund invests at least 50% of the fixed-income portion of its assets in investment grade debt securities. The Fund will limit its investment in high-yield/high-risk bonds, also known as “junk” bonds, to 50% or less of the fixed-income portion of its net assets. In addition to considering economic factors such as the effect of interest rates on the Fund’s fixed-income investments, the Fund’s fixed-income portfolio managers apply a “bottom up” approach in choosing investments. This means that the portfolio managers look at income-producing securities one at a time to determine if a security is an attractive investment opportunity and if it is consistent with the Fund’s investment policies. The Fund may also invest in foreign equity and debt securities, which may include investments in emerging markets. The Fund may also invest its assets in derivatives, which are instruments that have a value derived from, or directly linked to, an underlying asset, such as equity securities, fixed-income securities, commodities, currencies, interest rates, or market indices. The Fund has and is expected to continue to buy and sell put and call options to enhance returns. The Fund’s exposure to derivatives will vary, is not limited to those derivatives listed, and could be significant at times. Janus Capital is primarily responsible for the overall asset allocation of the Fund and manages the Fund’s fixed-income investments. Cash positions are considered a part of the Fund’s fixed-income allocation and will be managed by the Fund’s fixed-income portfolio managers. Perkins manages the Fund’s equity investments and assists the adviser in determining the Fund’s overall asset allocation. The Fund may periodically adjust its mix of equity and fixed-income investments in response to changing economic and market conditions, including outside the range of 40-60% of its assets in equity securities. Due to the nature of the fixed-income securities in which the Fund invests, it may have relatively high portfolio turnover compared to other funds. The Fund’s fixed-income portfolio managers may lend portfolio securities on a short-term or long-term basis, in an amount equal to up to 1/3 of its total assets as determined at the time of the loan origination.
Risk [Heading]	rr_RiskHeading	PRINCIPAL INVESTMENT RISKS
Risk Narrative [Text Block]	rr_RiskNarrativeTextBlock	The biggest risk is that the Fund’s returns and yields will vary, and you could lose money. The Fund is designed for long-term investors seeking a portfolio including common stocks and bonds selected for their potential to produce capital appreciation and current income. Common stocks tend to be more volatile than many other investment choices. Market Risk. The value of the Fund’s portfolio may decrease if the value of an individual company or security, or multiple companies or securities, in the portfolio decreases or if the portfolio managers’ belief about a company’s intrinsic worth is incorrect. Further, regardless of how well individual companies or securities perform, the value of the Fund’s portfolio could also decrease if there are deteriorating economic or market conditions. It is important to understand that the value of your investment may fall, sometimes sharply, in response to changes in the market, and you could lose money. Value Investing Risk. Because different types of stocks tend to shift in and out of favor depending on market and economic conditions, “value” stocks may perform differently than other types of stocks and from the market as a whole, and can continue to be undervalued by the market for long periods of time. It is also possible that a value stock will never appreciate to the extent expected by the equity portfolio managers. Mid-Sized Companies Risk. The Fund’s investments in securities issued by mid-sized companies may involve greater risks than are customarily associated with larger, more established companies. Securities issued by mid-sized companies tend to be more volatile than securities issued by larger or more established companies and may underperform as compared to the securities of larger companies. Fixed-Income Securities Risk. The Fund invests in a variety of fixed-income securities. Typically, the values of fixed-income securities change inversely with prevailing interest rates. Therefore, a fundamental risk of fixed-income securities is interest rate risk, which is the risk that the value of such securities will generally decline as prevailing interest rates rise, which may cause the Fund’s net asset value to likewise decrease. How specific fixed-income securities may react to changes in interest rates will depend on the specific characteristics of each security. Fixed-income securities are also subject to credit risk, prepayment risk, valuation risk, and liquidity risk. Credit risk is the risk that the credit strength of an issuer of a fixed-income security will weaken and/or that the issuer will be unable to make timely principal and interest payments and that the security may go into default. Prepayment risk is the risk that during periods of falling interest rates, certain fixed-income securities with higher interest rates, such as mortgage- and asset-backed securities, may be prepaid by their issuers thereby reducing the amount of interest payments. Valuation risk is the risk that one or more of the fixed-income securities in which the Fund invests are priced differently than the value realized upon such security’s sale. In times of market instability, valuation may be more difficult. Liquidity risk is the risk that fixed-income securities may be difficult or impossible to sell at the time that the portfolio managers would like or at the price the portfolio managers believe the security is currently worth. Mortgage-Backed Securities Risk. Mortgage-backed securities are classified generally as either commercial mortgage-backed securities or residential mortgage-backed securities, each of which is subject to certain specific risks. Mortgage-backed securities tend to be more sensitive to changes in interest rates than other types of debt securities. Investments in mortgage-backed securities are subject to both extension risk, where borrowers extend the duration of their mortgages in times of rising interest rates, and prepayment risk, where borrowers pay off their mortgages sooner than expected in times of declining interest rates. These risks may reduce the Fund’s returns. In addition, investments in mortgage-backed securities, including those comprised of subprime mortgages, may be subject to a higher degree of credit risk, valuation risk, and liquidity risk than various other types of fixed-income securities. High-Yield/High-Risk Bond Risk. High-yield/high-risk bonds may be more sensitive than other types of bonds to economic changes, political changes, or adverse developments specific to the company that issued the bond, which may adversely affect their value. Bank Loan Risk. Bank loans are obligations of companies or other entities entered into in connection with recapitalizations, acquisitions, and refinancings. The Fund’s investments in bank loans are generally acquired as a participation interest in, or assignment of, loans originated by a lender or other financial institution. These investments may include institutionally-traded floating and fixed-rate debt securities. Participation interests and assignments involve credit, interest rate, and liquidity risk. In addition, the bank loans underlying these securities often involve borrowers with low credit ratings whose financial conditions are troubled or uncertain, including companies that are highly leveraged or in bankruptcy proceedings. Foreign Exposure Risk. The Fund may have exposure to foreign markets as a result of its investments in foreign securities, including investments in emerging markets, which can be more volatile than the U.S. markets. As a result, its returns and net asset value may be affected to a large degree by fluctuations in currency exchange rates or political or economic conditions in a particular country. In some foreign markets, there may not be protection against failure by other parties to complete transactions. It may not be possible for the Fund to repatriate capital, dividends, interest, and other income from a particular country or governmental entity. In addition, a market swing in one or more countries or regions where the Fund has invested a significant amount of its assets may have a greater effect on the Fund’s performance than it would in a more geographically diversified portfolio. To the extent the Fund invests in foreign debt securities, such investments are sensitive to changes in interest rates. Additionally, investments in securities of foreign governments involve the risk that a foreign government may not be willing or able to pay interest or repay principal when due. The Fund’s investments in emerging market countries may involve risks greater than, or in addition to, the risks of investing in more developed countries. Eurozone Risk. A number of countries in the European Union (“EU”) have experienced severe economic and financial difficulties. As a result, financial markets in the EU have been subject to extreme volatility and declines in asset values and liquidity. Responses to these financial problems by European governments, central banks, and others, including austerity measures and reforms, may not work, may result in social unrest, and may limit future growth and economic recovery or have other unintended consequences. Further defaults or restructurings by governments and others of their debt could have additional adverse effects on economies, financial markets, and asset valuations around the world. To the extent that the Fund has exposure to European markets or to transactions tied to the value of the euro, these events could negatively affect the value and liquidity of the Fund’s investments. Sovereign Debt Risk. The Fund may invest in U.S. and foreign government debt securities (“sovereign debt”). Investments in U.S. sovereign debt are considered low risk. However, investments in non-U.S. sovereign debt can involve a high degree of risk, including the risk that the governmental entity that controls the repayment of sovereign debt may not be willing or able to repay the principal and/or to pay the interest on its sovereign debt in a timely manner. A sovereign debtor’s willingness or ability to satisfy its debt obligation may be affected by various factors including, but not limited to, its cash flow situation, the extent of its foreign currency reserves, the availability of foreign exchange when a payment is due, and the relative size of its debt position in relation to its economy as a whole. In the event of default, there may be limited or no legal remedies for collecting sovereign debt and there may be no bankruptcy proceedings through which the Fund may collect all or part of the sovereign debt that a governmental entity has not repaid. Real Estate Securities Risk. The Fund’s performance may be affected by the risks associated with investments in real estate-related companies. The value of real estate-related companies’ securities is sensitive to changes in real estate values and rental income, property taxes, interest rates, tax and regulatory requirements, supply and demand, and the management skill and creditworthiness of the company. Investments in real estate investment trusts (“REITs”) involve the same risks as other real estate investments. In addition, a REIT could fail to qualify for tax-free pass-through of its income under the Internal Revenue Code or fail to maintain its exemption from registration under the Investment Company Act of 1940, as amended, which could produce adverse economic consequences for the REIT and its investors, including the Fund. Derivatives Risk. Derivatives can be highly volatile and involve risks in addition to the risks of the underlying referenced securities. Gains or losses from a derivative investment can be substantially greater than the derivative’s original cost, and can therefore involve leverage. Leverage may cause the Fund to be more volatile than if it had not used leverage. Derivatives can be complex instruments and may involve analysis that differs from that required for other investment types used by the Fund. If the value of a derivative does not correlate well with the particular market or other asset class to which the derivative is intended to provide exposure, the derivative may not produce the anticipated result. Derivatives can also reduce the opportunity for gain or result in losses by offsetting positive returns in other investments. Derivatives can be less liquid than other types of investments and entail the risk that the counterparty will default on its payment obligations. If the counterparty to a derivative transaction defaults, the Fund would risk the loss of the net amount of the payments that it contractually is entitled to receive. To the extent the Fund enters into short derivative positions, the Fund may be exposed to risks similar to those associated with short sales, including the risk that the Fund’s losses are theoretically unlimited. Allocation Risk. The Fund’s ability to achieve its investment objective depends largely upon the allocation of assets among the equity and fixed asset categories. You could lose money on your investment in the Fund as a result of these allocations. Portfolio management may favor an asset category that underperforms relative to other asset categories. For example, the Fund may be overweighted in equity securities when the stock market is falling and the fixed-income market is rising. Additionally, periodic rebalancing of Fund assets among asset categories may result in increased transaction costs, which may have a negative effect on the Fund’s performance. Portfolio Turnover Risk. Increased portfolio turnover may result in higher costs, which may have a negative effect on the Fund’s performance. In addition, higher portfolio turnover may result in the acceleration of capital gains and the recognition of greater levels of short-term capital gains, which are taxed at ordinary federal income tax rates when distributed to shareholders. Securities Lending Risk. The Fund’s fixed-income portfolio managers may seek to earn additional income through lending its securities to certain qualified broker-dealers and institutions. There is the risk that when portfolio securities are lent, the securities may not be returned on a timely basis, and the Fund may experience delays and costs in recovering the security or gaining access to the collateral provided to the Fund to collateralize the loan. If the Fund is unable to recover a security on loan, the Fund may use the collateral to purchase replacement securities in the market. There is a risk that the value of the collateral could decrease below the cost of the replacement security by the time the replacement investment is made, resulting in a loss to the Fund. An investment in the Fund is not a bank deposit and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency.
Risk Lose Money [Text]	rr_RiskLoseMoney	The biggest risk is that the Fund’s returns and yields will vary, and you could lose money.
Risk Not Insured Depository Institution [Text]	rr_RiskNotInsuredDepositoryInstitution	An investment in the Fund is not a bank deposit and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency.
Bar Chart and Performance Table [Heading]	rr_BarChartAndPerformanceTableHeading	PERFORMANCE INFORMATION
Performance Narrative [Text Block]	rr_PerformanceNarrativeTextBlock	The following information provides some indication of the risks of investing in the Fund by showing how the Fund’s performance has varied over time. Class A Shares, Class C Shares, Class S Shares, Class I Shares, and Class T Shares of the Fund commenced operations with the Fund’s inception. The performance shown for Class A Shares, Class C Shares, Class S Shares, Class I Shares, and Class T Shares is calculated using the fees and expenses of each respective share class, net of any applicable fee and expense limitations or waivers. The performance shown for Class N Shares reflects the performance of the Fund’s Class I Shares, calculated using the fees and expenses of Class N Shares, without the effect of any fee and expense limitations or waivers. If Class N Shares of the Fund had been available during the periods shown, the performance may have been different. The bar chart depicts the change in performance from year to year during the periods indicated. The bar chart figures do not include any applicable sales charges that an investor may pay when they buy or sell Class A Shares or Class C Shares of the Fund. If sales charges were included, the returns would be lower. The table compares the Fund’s average annual returns for the periods indicated to broad-based securities market indices. The indices are not actively managed and are not available for direct investment. All figures assume reinvestment of dividends and distributions. For certain periods, the Fund’s performance reflects the effect of expense waivers. Without the effect of these expense waivers, the performance shown would have been lower. The Fund’s past performance (before and after taxes) does not necessarily indicate how it will perform in the future. Updated performance information is available at janus.com/advisor/mutual-funds or by calling 1-877-335-2687.
Performance Information Illustrates Variability of Returns [Text]	rr_PerformanceInformationIllustratesVariabilityOfReturns	The following information provides some indication of the risks of investing in the Fund by showing how the Fund’s performance has varied over time. The bar chart depicts the change in performance from year to year during the periods indicated.
Performance Additional Market Index [Text]	rr_PerformanceAdditionalMarketIndex	The table compares the Fund’s average annual returns for the periods indicated to broad-based securities market indices. The indices are not actively managed and are not available for direct investment. All figures assume reinvestment of dividends and distributions.
Performance Availability Phone [Text]	rr_PerformanceAvailabilityPhone	1-877-335-2687
Performance Availability Website Address [Text]	rr_PerformanceAvailabilityWebSiteAddress	janus.com/advisor/mutual-funds
Performance Past Does Not Indicate Future [Text]	rr_PerformancePastDoesNotIndicateFuture	The Fund’s past performance (before and after taxes) does not necessarily indicate how it will perform in the future.
Bar Chart [Heading]	rr_BarChartHeading	Annual Total Returns for Class I Shares (calendar year-end)
Bar Chart Does Not Reflect Sales Loads [Text]	rr_BarChartDoesNotReflectSalesLoads	The bar chart figures do not include any applicable sales charges that an investor may pay when they buy or sell Class A Shares or Class C Shares of the Fund. If sales charges were included, the returns would be lower.
Bar Chart Closing [Text Block]	rr_BarChartClosingTextBlock	Best Quarter:  Fourth Quarter 2011  7.22%          Worst Quarter:  Third Quarter 2011  −7.73%
Year to Date Return, Label	rr_YearToDateReturnLabel	The Fund’s year-to-date return as of the calendar quarter ended September 30, 2013 was 9.16%.
Performance Table Heading	rr_PerformanceTableHeading	Average Annual Total Returns (periods ended 12/31/12)
Performance Table Uses Highest Federal Rate	rr_PerformanceTableUsesHighestFederalRate	After-tax returns are calculated using the historically highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes.
Performance Table Not Relevant to Tax Deferred	rr_PerformanceTableNotRelevantToTaxDeferred	Actual after-tax returns depend on your individual tax situation and may differ from those shown in the preceding table. The after-tax return information shown above does not apply to Fund shares held through a tax-deferred account, such as a 401(k) plan or an IRA.
Performance Table One Class of after Tax Shown [Text]	rr_PerformanceTableOneClassOfAfterTaxShown	After-tax returns are only shown for Class I Shares of the Fund. After-tax returns for the other classes of Shares will vary from those shown for Class I Shares due to varying sales charges (as applicable), fees, and expenses among the classes.
Performance Table Narrative	rr_PerformanceTableNarrativeTextBlock	The Value Income Index is an internally-calculated, hypothetical combination of unmanaged indices that combines total returns from the Russell 1000® Value Index (50%) and the Barclays U.S. Aggregate Bond Index (50%). After-tax returns are calculated using the historically highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes. Actual after-tax returns depend on your individual tax situation and may differ from those shown in the preceding table. The after-tax return information shown above does not apply to Fund shares held through a tax-deferred account, such as a 401(k) plan or an IRA. After-tax returns are only shown for Class I Shares of the Fund. After-tax returns for the other classes of Shares will vary from those shown for Class I Shares due to varying sales charges (as applicable), fees, and expenses among the classes.
Performance Table Closing [Text Block]	rr_PerformanceTableClosingTextBlock	Updated performance information is available at janus.com/advisor/mutual-funds or by calling 1-877-335-2687.
Perkins Value Plus Income Fund | Class A, C, S, I, N, T Shares | Class A
Risk/Return:	rr_RiskReturnAbstract
Shareholder Fees Column [Text]	rr_ShareholderFeesColumnName	Class A
Maximum Sales Charge (load) Imposed on Purchases (as a percentage of offering price)	rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice	5.75%
Maximum Deferred Sales Charge (load) (as a percentage of the lower of original purchase price or redemption proceeds)	rr_MaximumDeferredSalesChargeOverOther	none
Operating Expenses Column [Text]	rr_OperatingExpensesColumnName	Class A
Management Fees	rr_ManagementFeesOverAssets	0.60%
Distribution/Service (12b-1) Fees	rr_DistributionAndService12b1FeesOverAssets	0.25%
Other Expenses	rr_OtherExpensesOverAssets	0.51%
Total Annual Fund Operating Expenses	rr_ExpensesOverAssets	1.36%	[1]
Fee Waiver	rr_FeeWaiverOrReimbursementOverAssets	0.41%	[1]
Total Annual Fund Operating Expenses After Fee Waiver	rr_NetExpensesOverAssets	0.95%	[1]
Expense Example, By Year, Column [Text]	rr_ExpenseExampleByYearColumnName	Class A Shares
1 Year	rr_ExpenseExampleYear01	706
3 Years	rr_ExpenseExampleYear03	981
5 Years	rr_ExpenseExampleYear05	1,277
10 Years	rr_ExpenseExampleYear10	2,116
Expense Example, No Redemption, By Year, Column [Text]	rr_ExpenseExampleNoRedemptionByYearColumnName	Class A Shares
1 Year	rr_ExpenseExampleNoRedemptionYear01	706
3 Years	rr_ExpenseExampleNoRedemptionYear03	981
5 Years	rr_ExpenseExampleNoRedemptionYear05	1,277
10 Years	rr_ExpenseExampleNoRedemptionYear10	2,116
Perkins Value Plus Income Fund | Class A, C, S, I, N, T Shares | Class C
Risk/Return:	rr_RiskReturnAbstract
Shareholder Fees Column [Text]	rr_ShareholderFeesColumnName	Class C
Maximum Sales Charge (load) Imposed on Purchases (as a percentage of offering price)	rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice	none
Maximum Deferred Sales Charge (load) (as a percentage of the lower of original purchase price or redemption proceeds)	rr_MaximumDeferredSalesChargeOverOther	1.00%
Operating Expenses Column [Text]	rr_OperatingExpensesColumnName	Class C
Management Fees	rr_ManagementFeesOverAssets	0.60%
Distribution/Service (12b-1) Fees	rr_DistributionAndService12b1FeesOverAssets	1.00%
Other Expenses	rr_OtherExpensesOverAssets	0.53%
Total Annual Fund Operating Expenses	rr_ExpensesOverAssets	2.13%	[1]
Fee Waiver	rr_FeeWaiverOrReimbursementOverAssets	0.44%	[1]
Total Annual Fund Operating Expenses After Fee Waiver	rr_NetExpensesOverAssets	1.69%	[1]
Expense Example, By Year, Column [Text]	rr_ExpenseExampleByYearColumnName	Class C Shares
1 Year	rr_ExpenseExampleYear01	316
3 Years	rr_ExpenseExampleYear03	667
5 Years	rr_ExpenseExampleYear05	1,144
10 Years	rr_ExpenseExampleYear10	2,462
Expense Example, No Redemption, By Year, Column [Text]	rr_ExpenseExampleNoRedemptionByYearColumnName	Class C Shares
1 Year	rr_ExpenseExampleNoRedemptionYear01	216
3 Years	rr_ExpenseExampleNoRedemptionYear03	667
5 Years	rr_ExpenseExampleNoRedemptionYear05	1,144
10 Years	rr_ExpenseExampleNoRedemptionYear10	2,462
Perkins Value Plus Income Fund | Class A, C, S, I, N, T Shares | Class S
Risk/Return:	rr_RiskReturnAbstract
Shareholder Fees Column [Text]	rr_ShareholderFeesColumnName	Class S
Maximum Sales Charge (load) Imposed on Purchases (as a percentage of offering price)	rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice	none
Maximum Deferred Sales Charge (load) (as a percentage of the lower of original purchase price or redemption proceeds)	rr_MaximumDeferredSalesChargeOverOther	none
Operating Expenses Column [Text]	rr_OperatingExpensesColumnName	Class S
Management Fees	rr_ManagementFeesOverAssets	0.60%
Distribution/Service (12b-1) Fees	rr_DistributionAndService12b1FeesOverAssets	0.25%
Other Expenses	rr_OtherExpensesOverAssets	0.74%
Total Annual Fund Operating Expenses	rr_ExpensesOverAssets	1.59%	[1]
Fee Waiver	rr_FeeWaiverOrReimbursementOverAssets	0.41%	[1]
Total Annual Fund Operating Expenses After Fee Waiver	rr_NetExpensesOverAssets	1.18%	[1]
Expense Example, By Year, Column [Text]	rr_ExpenseExampleByYearColumnName	Class S Shares
1 Year	rr_ExpenseExampleYear01	162
3 Years	rr_ExpenseExampleYear03	502
5 Years	rr_ExpenseExampleYear05	866
10 Years	rr_ExpenseExampleYear10	1,889
Expense Example, No Redemption, By Year, Column [Text]	rr_ExpenseExampleNoRedemptionByYearColumnName	Class S Shares
1 Year	rr_ExpenseExampleNoRedemptionYear01	162
3 Years	rr_ExpenseExampleNoRedemptionYear03	502
5 Years	rr_ExpenseExampleNoRedemptionYear05	866
10 Years	rr_ExpenseExampleNoRedemptionYear10	1,889
Perkins Value Plus Income Fund | Class A, C, S, I, N, T Shares | Class I
Risk/Return:	rr_RiskReturnAbstract
Shareholder Fees Column [Text]	rr_ShareholderFeesColumnName	Class I
Maximum Sales Charge (load) Imposed on Purchases (as a percentage of offering price)	rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice	none
Maximum Deferred Sales Charge (load) (as a percentage of the lower of original purchase price or redemption proceeds)	rr_MaximumDeferredSalesChargeOverOther	none
Operating Expenses Column [Text]	rr_OperatingExpensesColumnName	Class I
Management Fees	rr_ManagementFeesOverAssets	0.60%
Distribution/Service (12b-1) Fees	rr_DistributionAndService12b1FeesOverAssets	none
Other Expenses	rr_OtherExpensesOverAssets	0.50%
Total Annual Fund Operating Expenses	rr_ExpensesOverAssets	1.10%	[1]
Fee Waiver	rr_FeeWaiverOrReimbursementOverAssets	0.42%	[1]
Total Annual Fund Operating Expenses After Fee Waiver	rr_NetExpensesOverAssets	0.68%	[1]
Expense Example, By Year, Column [Text]	rr_ExpenseExampleByYearColumnName	Class I Shares
1 Year	rr_ExpenseExampleYear01	112
3 Years	rr_ExpenseExampleYear03	350
5 Years	rr_ExpenseExampleYear05	606
10 Years	rr_ExpenseExampleYear10	1,340
Expense Example, No Redemption, By Year, Column [Text]	rr_ExpenseExampleNoRedemptionByYearColumnName	Class I Shares
1 Year	rr_ExpenseExampleNoRedemptionYear01	112
3 Years	rr_ExpenseExampleNoRedemptionYear03	350
5 Years	rr_ExpenseExampleNoRedemptionYear05	606
10 Years	rr_ExpenseExampleNoRedemptionYear10	1,340
2011	rr_AnnualReturn2011	3.74%
2012	rr_AnnualReturn2012	11.75%
Bar Chart, Year to Date Return, Date	rr_BarChartYearToDateReturnDate	Sep. 30, 2013
Bar Chart, Year to Date Return	rr_BarChartYearToDateReturn	9.16%
Highest Quarterly Return, Label	rr_HighestQuarterlyReturnLabel	Best Quarter:
Highest Quarterly Return, Date	rr_BarChartHighestQuarterlyReturnDate	Dec. 31, 2011
Highest Quarterly Return	rr_BarChartHighestQuarterlyReturn	7.22%
Lowest Quarterly Return, Label	rr_LowestQuarterlyReturnLabel	Worst Quarter:
Lowest Quarterly Return, Date	rr_BarChartLowestQuarterlyReturnDate	Sep. 30, 2011
Lowest Quarterly Return	rr_BarChartLowestQuarterlyReturn	(7.73%)
Perkins Value Plus Income Fund | Class A, C, S, I, N, T Shares | Class N
Risk/Return:	rr_RiskReturnAbstract
Shareholder Fees Column [Text]	rr_ShareholderFeesColumnName	Class N
Maximum Sales Charge (load) Imposed on Purchases (as a percentage of offering price)	rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice	none
Maximum Deferred Sales Charge (load) (as a percentage of the lower of original purchase price or redemption proceeds)	rr_MaximumDeferredSalesChargeOverOther	none
Operating Expenses Column [Text]	rr_OperatingExpensesColumnName	Class N
Management Fees	rr_ManagementFeesOverAssets	0.60%
Distribution/Service (12b-1) Fees	rr_DistributionAndService12b1FeesOverAssets	none
Other Expenses	rr_OtherExpensesOverAssets	0.50%	[2]
Total Annual Fund Operating Expenses	rr_ExpensesOverAssets	1.10%	[1]
Fee Waiver	rr_FeeWaiverOrReimbursementOverAssets	0.42%	[1]
Total Annual Fund Operating Expenses After Fee Waiver	rr_NetExpensesOverAssets	0.68%	[1]
Expense Example, By Year, Column [Text]	rr_ExpenseExampleByYearColumnName	Class N Shares
1 Year	rr_ExpenseExampleYear01	112
3 Years	rr_ExpenseExampleYear03	350
5 Years	rr_ExpenseExampleYear05	606
10 Years	rr_ExpenseExampleYear10	1,340
Expense Example, No Redemption, By Year, Column [Text]	rr_ExpenseExampleNoRedemptionByYearColumnName	Class N Shares
1 Year	rr_ExpenseExampleNoRedemptionYear01	112
3 Years	rr_ExpenseExampleNoRedemptionYear03	350
5 Years	rr_ExpenseExampleNoRedemptionYear05	606
10 Years	rr_ExpenseExampleNoRedemptionYear10	1,340
Perkins Value Plus Income Fund | Class A, C, S, I, N, T Shares | Class T
Risk/Return:	rr_RiskReturnAbstract
Shareholder Fees Column [Text]	rr_ShareholderFeesColumnName	Class T
Maximum Sales Charge (load) Imposed on Purchases (as a percentage of offering price)	rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice	none
Maximum Deferred Sales Charge (load) (as a percentage of the lower of original purchase price or redemption proceeds)	rr_MaximumDeferredSalesChargeOverOther	none
Operating Expenses Column [Text]	rr_OperatingExpensesColumnName	Class T
Management Fees	rr_ManagementFeesOverAssets	0.60%
Distribution/Service (12b-1) Fees	rr_DistributionAndService12b1FeesOverAssets	none
Other Expenses	rr_OtherExpensesOverAssets	0.73%
Total Annual Fund Operating Expenses	rr_ExpensesOverAssets	1.33%	[1]
Fee Waiver	rr_FeeWaiverOrReimbursementOverAssets	0.40%	[1]
Total Annual Fund Operating Expenses After Fee Waiver	rr_NetExpensesOverAssets	0.93%	[1]
Expense Example, By Year, Column [Text]	rr_ExpenseExampleByYearColumnName	Class T Shares
1 Year	rr_ExpenseExampleYear01	135
3 Years	rr_ExpenseExampleYear03	421
5 Years	rr_ExpenseExampleYear05	729
10 Years	rr_ExpenseExampleYear10	1,601
Expense Example, No Redemption, By Year, Column [Text]	rr_ExpenseExampleNoRedemptionByYearColumnName	Class T Shares
1 Year	rr_ExpenseExampleNoRedemptionYear01	135
3 Years	rr_ExpenseExampleNoRedemptionYear03	421
5 Years	rr_ExpenseExampleNoRedemptionYear05	729
10 Years	rr_ExpenseExampleNoRedemptionYear10	$ 1,601
Perkins Value Plus Income Fund | Class A, C, S, I, N, T Shares | Return Before Taxes | Class A
Risk/Return:	rr_RiskReturnAbstract
Column	rr_AverageAnnualReturnColumnName	Class A Shares
Label	rr_AverageAnnualReturnLabel	Return Before Taxes	[3]
1 Year	rr_AverageAnnualReturnYear01	5.05%
Since Inception	rr_AverageAnnualReturnSinceInception	7.40%
Inception Date	rr_AverageAnnualReturnInceptionDate	Jul. 30, 2010
Perkins Value Plus Income Fund | Class A, C, S, I, N, T Shares | Return Before Taxes | Class C
Risk/Return:	rr_RiskReturnAbstract
Column	rr_AverageAnnualReturnColumnName	Class C Shares
Label	rr_AverageAnnualReturnLabel	Return Before Taxes	[4]
1 Year	rr_AverageAnnualReturnYear01	9.94%
Since Inception	rr_AverageAnnualReturnSinceInception	9.39%
Inception Date	rr_AverageAnnualReturnInceptionDate	Jul. 30, 2010
Perkins Value Plus Income Fund | Class A, C, S, I, N, T Shares | Return Before Taxes | Class S
Risk/Return:	rr_RiskReturnAbstract
Column	rr_AverageAnnualReturnColumnName	Class S Shares
Label	rr_AverageAnnualReturnLabel	Return Before Taxes
1 Year	rr_AverageAnnualReturnYear01	11.25%
Since Inception	rr_AverageAnnualReturnSinceInception	9.81%
Inception Date	rr_AverageAnnualReturnInceptionDate	Jul. 30, 2010
Perkins Value Plus Income Fund | Class A, C, S, I, N, T Shares | Return Before Taxes | Class I
Risk/Return:	rr_RiskReturnAbstract
Column	rr_AverageAnnualReturnColumnName	Class I Shares
Label	rr_AverageAnnualReturnLabel	Return Before Taxes
1 Year	rr_AverageAnnualReturnYear01	11.75%
Since Inception	rr_AverageAnnualReturnSinceInception	10.29%
Inception Date	rr_AverageAnnualReturnInceptionDate	Jul. 30, 2010
Perkins Value Plus Income Fund | Class A, C, S, I, N, T Shares | Return Before Taxes | Class N
Risk/Return:	rr_RiskReturnAbstract
Column	rr_AverageAnnualReturnColumnName	Class N Shares
Label	rr_AverageAnnualReturnLabel	Return Before Taxes
1 Year	rr_AverageAnnualReturnYear01	11.26%
Since Inception	rr_AverageAnnualReturnSinceInception	9.82%
Inception Date	rr_AverageAnnualReturnInceptionDate	Jul. 30, 2010
Perkins Value Plus Income Fund | Class A, C, S, I, N, T Shares | Return Before Taxes | Class T
Risk/Return:	rr_RiskReturnAbstract
Column	rr_AverageAnnualReturnColumnName	Class T Shares
Label	rr_AverageAnnualReturnLabel	Return Before Taxes
1 Year	rr_AverageAnnualReturnYear01	11.57%
Since Inception	rr_AverageAnnualReturnSinceInception	10.10%
Inception Date	rr_AverageAnnualReturnInceptionDate	Jul. 30, 2010
Perkins Value Plus Income Fund | Class A, C, S, I, N, T Shares | Return After Taxes on Distributions | Class I
Risk/Return:	rr_RiskReturnAbstract
Column	rr_AverageAnnualReturnColumnName	Class I Shares
Label	rr_AverageAnnualReturnLabel	Return After Taxes on Distributions
1 Year	rr_AverageAnnualReturnYear01	10.31%
Since Inception	rr_AverageAnnualReturnSinceInception	8.61%
Inception Date	rr_AverageAnnualReturnInceptionDate	Jul. 30, 2010
Perkins Value Plus Income Fund | Class A, C, S, I, N, T Shares | Return After Taxes on Distributions and Sale of Fund Shares | Class I
Risk/Return:	rr_RiskReturnAbstract
Column	rr_AverageAnnualReturnColumnName	Class I Shares
Label	rr_AverageAnnualReturnLabel	Return After Taxes on Distributions and Sale of Fund Shares
1 Year	rr_AverageAnnualReturnYear01	8.20%
Since Inception	rr_AverageAnnualReturnSinceInception	7.99%
Inception Date	rr_AverageAnnualReturnInceptionDate	Jul. 30, 2010
Perkins Value Plus Income Fund | Class A, C, S, I, N, T Shares | Russell 1000® Value Index (reflects no deduction for expenses, fees, or taxes)
Risk/Return:	rr_RiskReturnAbstract
Label	rr_AverageAnnualReturnLabel	Russell 1000® Value Index
1 Year	rr_AverageAnnualReturnYear01	17.51%
Since Inception	rr_AverageAnnualReturnSinceInception	13.02%
Inception Date	rr_AverageAnnualReturnInceptionDate	Jul. 30, 2010
Perkins Value Plus Income Fund | Class A, C, S, I, N, T Shares | Barclays U.S. Aggregate Bond Index (reflects no deduction for expenses, fees, or taxes)
Risk/Return:	rr_RiskReturnAbstract
Label	rr_AverageAnnualReturnLabel	Barclays U.S. Aggregate Bond Index
1 Year	rr_AverageAnnualReturnYear01	4.21%
Since Inception	rr_AverageAnnualReturnSinceInception	4.97%
Inception Date	rr_AverageAnnualReturnInceptionDate	Jul. 30, 2010
Perkins Value Plus Income Fund | Class A, C, S, I, N, T Shares | Value Income Index (reflects no deduction for expenses, fees, or taxes)
Risk/Return:	rr_RiskReturnAbstract
Label	rr_AverageAnnualReturnLabel	Value Income Index
1 Year	rr_AverageAnnualReturnYear01	10.84%
Since Inception	rr_AverageAnnualReturnSinceInception	9.26%
Inception Date	rr_AverageAnnualReturnInceptionDate	Jul. 30, 2010

[1] Janus Capital has contractually agreed to waive its investment advisory fee and/or reimburse Fund expenses to the extent that the Fund’s total annual fund operating expenses (excluding the distribution and shareholder servicing fees – applicable to Class A Shares, Class C Shares, and Class S Shares; administrative services fees payable pursuant to the Transfer Agency Agreement; brokerage commissions; interest; dividends; taxes; acquired fund fees and expenses; and extraordinary expenses) exceed 0.68% until at least November 1, 2014. The contractual waiver may be terminated or modified prior to this date only at the discretion of the Board of Trustees. For a period of three years subsequent to the Fund’s commencement of operations (July 30, 2010), Janus Capital may recover from the Fund fees and expenses previously waived or reimbursed, which could then be considered a deferral, if the Fund’s expense ratio, including recovered expenses, falls below the expense limit.

[2] Other Expenses for Class N Shares are based on the estimated annualized expenses that the Shares expect to incur.

[3] Calculated assuming maximum permitted sales loads.

[4] The one year return is calculated to include the contingent deferred sales charge.

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Perkins Mid Cap Value Fund | Class D Shares

FUND SUMMARY

Perkins Mid Cap Value Fund

INVESTMENT OBJECTIVE

Perkins Mid Cap Value Fund seeks capital appreciation.

FEES AND EXPENSES OF THE FUND

This table describes the fees and expenses that you may pay if you buy and hold Shares of the Fund.

ANNUAL FUND OPERATING EXPENSES
(expenses that you pay each year as a percentage of the value of your investment)

Annual Fund Operating Expenses	Perkins Mid Cap Value Fund Class D Shares Class D
Operating Expenses Column [Text]	Class D
Management Fees (may adjust up or down)	0.48%
Other Expenses	0.20%
Total Annual Fund Operating Expenses	0.68%

EXAMPLE:

The Example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds.

The Example assumes that you invest $10,000 in the Fund for the time periods indicated, reinvest all dividends and distributions, and then redeem all of your Shares at the end of each period. The Example also assumes that your investment has a 5% return each year and that the Fund’s operating expenses remain the same. Although your actual costs may be higher or lower, based on these assumptions your costs would be:

Expense Example (USD $)	Expense Example, By Year, Column [Text]	1 Year	3 Years	5 Years	10 Years
Perkins Mid Cap Value Fund Class D Shares Class D	Class D Shares	69	218	379	847

Portfolio Turnover: 

The Fund pays transaction costs, such as commissions, when it buys and sells securities (or “turns over” its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when Fund shares are held in a taxable account. These costs, which are not reflected in annual fund operating expenses or in the Example, affect the Fund’s performance. During the most recent fiscal year, the Fund’s portfolio turnover rate was 60% of the average value of its portfolio.

PRINCIPAL INVESTMENT STRATEGIES

The Fund pursues its investment objective by investing primarily in common stocks selected for their capital appreciation potential. The Fund primarily invests in the common stocks of mid-sized companies whose stock prices the portfolio managers believe to be undervalued. The Fund invests, under normal circumstances, at least 80% of its net assets in equity securities of companies whose market capitalization falls, at the time of purchase, within the 12-month average of the capitalization range of the Russell Midcap^® Value Index. This average is updated monthly. The market capitalizations within the index will vary, but as of June 30, 2013, they ranged from approximately $487 million to $30.3 billion. The Fund may also invest in foreign equity and debt securities, which may include investments in emerging markets. The Fund may invest, under normal circumstances, up to 20% of its net assets in securities of companies having market capitalizations outside of the aforementioned market capitalization ranges. In addition, when the portfolio managers believe that market conditions are unfavorable for investing, or when they are otherwise unable to locate attractive investment opportunities, the Fund may invest up to 20% of its net assets in cash or similar investments.

The Fund focuses on companies that have fallen out of favor with the market or that appear to be temporarily misunderstood by the investment community. The Fund’s portfolio managers generally look for companies with:

• strong balance sheets and solid recurring free cash flows
• attractive relative and absolute valuation ratios or that have underperformed recently
• favorable reward to risk characteristics

The Fund may invest in equity and debt securities of real estate-related companies. Such companies may include those in the real estate industry or real estate-related industries. These securities may include common stocks, preferred stocks, and other equity securities, including, but not limited to, mortgage-backed securities, real estate-backed securities, securities of real estate investment trusts (“REITs”) and similar REIT-like entities. A REIT is a trust that invests in real estate-related projects, such as properties, mortgage loans, and construction loans. REITs are generally categorized as equity, mortgage, or hybrid REITs. A REIT may be listed on an exchange or traded over-the-counter.

The Fund may also invest its assets in derivatives, which are instruments that have a value derived from, or directly linked to, an underlying asset, such as equity securities, fixed-income securities, commodities, currencies, interest rates, or market indices. The Fund from time to time may buy and sell put and call options, particularly on market indices, for hedging purposes (to offset risks associated with an investment, currency exposure, or market conditions) and to enhance returns. The Fund’s exposure to derivatives will vary, is not limited to those derivatives listed, and could be significant at times. For purposes of meeting its 80% investment policy, the Fund may include derivatives that have characteristics similar to the securities in which the Fund may directly invest.

PRINCIPAL INVESTMENT RISKS

The biggest risk is that the Fund’s returns will vary, and you could lose money. The Fund is designed for long-term investors seeking an equity portfolio, including common stocks. Common stocks tend to be more volatile than many other investment choices.

Value Investing Risk. Because different types of stocks tend to shift in and out of favor depending on market and economic conditions, “value” stocks may perform differently than other types of stocks and from the market as a whole, and can continue to be undervalued by the market for long periods of time. It is also possible that a value stock will never appreciate to the extent expected by the portfolio managers. When the Fund’s investments in cash or similar investments increase due to a lack of favorable investment opportunities or other extraordinary factors, the Fund may not participate in market advances or declines to the same extent that it would if the Fund had been fully invested.

Market Risk. The value of the Fund’s portfolio may decrease if the value of an individual company or security, or multiple companies or securities, in the portfolio decreases or if the portfolio managers’ belief about a company’s intrinsic worth is incorrect. Further, regardless of how well individual companies or securities perform, the value of the Fund’s portfolio could also decrease if there are deteriorating economic or market conditions. It is important to understand that the value of your investment may fall, sometimes sharply, in response to changes in the market, and you could lose money.

Mid-Sized Companies Risk. The Fund’s investments in securities issued by mid-sized companies may involve greater risks than are customarily associated with larger, more established companies. Securities issued by mid-sized companies tend to be more volatile than securities issued by larger or more established companies and may underperform as compared to the securities of larger companies.

Real Estate Securities Risk. The Fund’s performance may be affected by the risks associated with investments in real estate-related companies. The value of real estate-related companies’ securities is sensitive to changes in real estate values and rental income, property taxes, interest rates, tax and regulatory requirements, supply and demand, and the management skill and creditworthiness of the company. Investments in REITs involve the same risks as other real estate investments. In addition, a REIT could fail to qualify for tax-free pass-through of its income under the Internal Revenue Code or fail to maintain its exemption from registration under the Investment Company Act of 1940, as amended, which could produce adverse economic consequences for the REIT and its investors, including the Fund.

Foreign Exposure Risk. The Fund may have exposure to foreign markets as a result of its investments in foreign securities, including investments in emerging markets, which can be more volatile than the U.S. markets. As a result, its returns and net asset value may be affected to a large degree by fluctuations in currency exchange rates or political or economic conditions in a particular country. In some foreign markets, there may not be protection against failure by other parties to complete transactions. It may not be possible for the Fund to repatriate capital, dividends, interest, and other income from a particular country or governmental entity. In addition, a market swing in one or more countries or regions where the Fund has invested a significant amount of its assets may have a greater effect on the Fund’s performance than it would in a more geographically diversified portfolio. To the extent the Fund invests in foreign debt securities, such investments are sensitive to changes in interest rates. Additionally, investments in securities of foreign governments involve the risk that a foreign government may not be willing or able to pay interest or repay principal when due.

Derivatives Risk. Derivatives can be highly volatile and involve risks in addition to the risks of the underlying referenced securities. Gains or losses from a derivative investment can be substantially greater than the derivative’s original cost, and can therefore involve leverage. Leverage may cause the Fund to be more volatile than if it had not used leverage. Derivatives can be complex instruments and may involve analysis that differs from that required for other investment types used by the Fund. If the value of a derivative does not correlate well with the particular market or other asset class to which the derivative is intended to provide exposure, the derivative may not produce the anticipated result. Derivatives can also reduce the opportunity for gain or result in losses by offsetting positive returns in other investments. Derivatives can be less liquid than other types of investments and entail the risk that the counterparty will default on its payment obligations. If the counterparty to a derivative transaction defaults, the Fund would risk the loss of the net amount of the payments that it contractually is entitled to receive. To the extent the Fund enters into short derivative positions, the Fund may be exposed to risks similar to those associated with short sales, including the risk that the Fund’s losses are theoretically unlimited.

An investment in the Fund is not a bank deposit and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency.

PERFORMANCE INFORMATION

The following information provides some indication of the risks of investing in the Fund by showing how the Fund’s performance has varied over time. Class D Shares of the Fund commenced operations on February 16, 2010, as a result of the restructuring of Class J Shares. The performance shown for Class D Shares for periods prior to February 16, 2010, reflects the performance of the Fund’s former Class J Shares (formerly named Investor Shares). For the periods prior to April 21, 2003, the performance shown for Class D Shares reflects the historical performance of Berger Mid Cap Value Fund – Investor Shares (as a result of a prior reorganization of Berger Mid Cap Value Fund – Investor Shares into the Fund’s former Class J Shares). If Class D Shares of the Fund had been available during periods prior to February 16, 2010, the performance shown may have been different. The performance shown for periods following the Fund’s commencement of Class D Shares reflects the fees and expenses of Class D Shares, net of any applicable fee and expense limitations or waivers.

The bar chart depicts the change in performance from year to year during the periods indicated. The table compares the Fund’s average annual returns for the periods indicated to a broad-based securities market index. The index is not actively managed and is not available for direct investment. All figures assume reinvestment of dividends and distributions. For certain periods, the Fund’s performance reflects the effect of expense waivers. Without the effect of these expense waivers, the performance shown would have been lower.

The Fund’s past performance (before and after taxes) does not necessarily indicate how it will perform in the future. Updated performance information is available at janus.com/allfunds or by calling 1-800-525-3713.

Annual Total Returns for Class D Shares (calendar year-end)

Best Quarter:  Second Quarter 2003  17.17%          Worst Quarter:  Fourth Quarter 2008  −19.63%

The Fund’s year-to-date return as of the calendar quarter ended September 30, 2013 was 17.47%.

Average Annual Total Returns (periods ended 12/31/12)

Average Annual Total Returns Perkins Mid Cap Value Fund Class D Shares	Column	Label		1 Year	5 Years	10 Years	Since Inception of Predecessor Fund	Inception Date
Class D Return Before Taxes	Class D Shares	Return Before Taxes		10.43%	3.24%	10.21%	11.68%	Aug. 12, 1998
Class D Return After Taxes on Distributions	Class D Shares	Return After Taxes on Distributions		9.72%	2.58%	9.02%	10.28%	Aug. 12, 1998
Class D Return After Taxes on Distributions and Sale of Fund Shares	Class D Shares	Return After Taxes on Distributions and Sale of Fund Shares	[1]	7.72%	2.66%	8.70%	9.91%	Aug. 12, 1998
Russell Midcap® Value Index (reflects no deduction for expenses, fees, or taxes)		Russell Midcap® Value Index		18.51%	3.79%	10.63%	8.42%	Aug. 12, 1998

The Russell Midcap^® Value Index measures the performance of those Russell Midcap^® companies with lower price-to-book ratios and lower forecasted growth values. The stocks are also members of the Russell 1000^® Value Index. This index is used to calculate the performance fee adjustment.

After-tax returns are calculated using distributions for the Fund’s Class D Shares for the periods following February 16, 2010; for the Fund’s Class J Shares (formerly named Investor Shares) for the period April 21, 2003 to February 16, 2010; and for Berger Mid Cap Value Fund – Investor Shares for periods prior to April 21, 2003. If Class D Shares of the Fund had been available during these earlier periods, distributions may have been different and thus, after-tax returns may have been different from those shown. After-tax returns are calculated using the historically highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes. Actual after-tax returns depend on your individual tax situation and may differ from those shown in the preceding table. The after-tax return information shown above does not apply to Fund shares held through a tax-deferred account, such as a 401(k) plan or an IRA.

[1] If the Fund incurs a loss, which generates a tax benefit, the Return After Taxes on Distributions and Sale of Fund Shares may exceed the Fund’s other return figures.

XML

Label	Element	Value
Risk/Return:	rr_RiskReturnAbstract
Registrant Name	dei_EntityRegistrantName	JANUS INVESTMENT FUND
Prospectus Date	rr_ProspectusDate	Oct. 28, 2013
Janus Diversified Alternatives Fund | Class A, C, S, I, N, T Shares
Risk/Return:	rr_RiskReturnAbstract
Risk/Return [Heading]	rr_RiskReturnHeading	FUND SUMMARY Janus Diversified Alternatives Fund
Objective [Heading]	rr_ObjectiveHeading	INVESTMENT OBJECTIVE
Objective, Primary [Text Block]	rr_ObjectivePrimaryTextBlock	Janus Diversified Alternatives Fund seeks absolute return with low correlation to stocks and bonds.
Expense [Heading]	rr_ExpenseHeading	FEES AND EXPENSES OF THE FUND
Expense Narrative [Text Block]	rr_ExpenseNarrativeTextBlock	This table describes the fees and expenses that you may pay if you buy and hold Shares of the Fund. Each share class has different expenses, but represents an investment in the same Fund.
Shareholder Fees Caption [Text]	rr_ShareholderFeesCaption	SHAREHOLDER FEES (fees paid directly from your investment)
Operating Expenses Caption [Text]	rr_OperatingExpensesCaption	ANNUAL FUND OPERATING EXPENSES (expenses that you pay each year as a percentage of the value of your investment)
Fee Waiver or Reimbursement over Assets, Date of Termination	rr_FeeWaiverOrReimbursementOverAssetsDateOfTermination	November 1, 2014
Portfolio Turnover [Heading]	rr_PortfolioTurnoverHeading	Portfolio Turnover:
Portfolio Turnover [Text Block]	rr_PortfolioTurnoverTextBlock	The Fund pays transaction costs, such as commissions, when it buys and sells securities (or “turns over” its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when Fund shares are held in a taxable account. These costs, which are not reflected in annual fund operating expenses or in the Example, affect the Fund’s performance. During the period December 28, 2012 to June 30, 2013, the Fund’s portfolio turnover rate was 38% of the average value of its portfolio.
Portfolio Turnover, Rate	rr_PortfolioTurnoverRate	38.00%
Expense Breakpoint Discounts [Text]	rr_ExpenseBreakpointDiscounts	For Class A Shares, you may qualify for sales charge discounts if you and your family invest, or agree to invest in the future, at least $50,000 in the Fund or in other Janus mutual funds. More information about these and other discounts, as well as eligibility requirements for each share class, is available from your financial professional and in the “Purchases” section on page 36 of the Fund’s Prospectus and in the “Purchases” section on page 49 of the Fund’s Statement of Additional Information.
Expense Breakpoint, Minimum Investment Required [Amount]	rr_ExpenseBreakpointMinimumInvestmentRequiredAmount	$ 50,000
Expense Example [Heading]	rr_ExpenseExampleHeading	EXAMPLE:
Expense Example by Year [Heading]	rr_ExpenseExampleByYearHeading	The Example assumes that you invest $10,000 in the Fund for the time periods indicated and reinvest all dividends and distributions. The Example also assumes that your investment has a 5% return each year and that the Fund’s operating expenses without waivers or recoupments (if applicable) remain the same. Although your actual costs may be higher or lower, based on these assumptions your costs would be:
Expense Example Narrative [Text Block]	rr_ExpenseExampleNarrativeTextBlock	The following Example is based on expenses without waivers. The Example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds.
Expense Example by, Year, Caption [Text]	rr_ExpenseExampleByYearCaption	If Shares are redeemed:
Expense Example, No Redemption, By Year, Caption [Text]	rr_ExpenseExampleNoRedemptionByYearCaption	If Shares are not redeemed:
Strategy [Heading]	rr_StrategyHeading	PRINCIPAL INVESTMENT STRATEGIES
Strategy Narrative [Text Block]	rr_StrategyNarrativeTextBlock	Under normal market conditions, the Fund pursues its investment objective by investing in a diverse group of return drivers, each a type of risk premium (collectively, “risk premia”), across equity, fixed income, commodity, and currency asset classes. Risk premia refers to the return that is expected for assuming a particular market risk. For example, investors expect a higher return in exchange for the perceived risks associated with investing in emerging markets as compared to investing in developed markets. Accordingly, a belief that emerging market equities may outperform developed market equities presents a risk premia opportunity. The Fund seeks to generate returns by identifying and isolating diverse sources of potential risk premia, and combining risk premia into a liquid portfolio that seeks to deliver consistent, absolute returns with a low correlation to the returns generated by investments in stocks and bonds. There is no guarantee that the portfolio will be successful in meeting this objective. The Fund employs a proprietary multi-factor process to allocate the Fund’s assets across the various risk premia. The process begins with an approximate equal-weighted risk to each risk premium in which the Fund invests, so that no individual risk premium contributes disproportionately to the Fund’s overall risk profile and expected returns over the long term. Next, the Fund applies additional advanced allocation methodologies to the portfolio to tactically adjust the weights of risk premia. The Fund’s portfolio managers generally rebalance risk premia allocations quarterly, but may rebalance such allocations more often from time to time to adjust the Fund’s relative risk premia exposures. The rebalancing techniques used by the Fund’s portfolio managers may result in a higher portfolio turnover rate and related expenses compared to a “buy and hold” fund strategy. The Fund may not utilize all identified risk premia in its investment process at all times. Janus Capital believes that this allocation process may provide better risk adjusted returns than a traditional asset allocation strategy that employs fixed weights for asset classes. The Fund employs various strategies within the equity, fixed income, commodity, and currency asset classes to identify risk premia and generate returns, including, but not limited to, relative value, momentum, credit, size, roll yield, systematic, and currency carry. Relative Value – Relative Value investing seeks to capture the spread between a relatively undervalued asset and a more expensive one. For example, one pool of equities often outperforms another pool of equities in a different sector or investment style. Relative value attempts to identify the difference in valuation associated with those assets and favors investments in the relatively undervalued pool to generate return. Momentum – Momentum investing seeks to capitalize on the expected continuance of trends in the market. For example, if interest rates are increasing, a momentum investor would invest in securities that would generate positive returns if rates continue to increase in the near term. Credit – Credit investing seeks to invest in fixed-income securities to realize the additional rate of return that corporate debt provides as compared to U.S. Treasuries. Size – Size investing seeks to generate returns by investing in small capitalization equity securities over large capitalization equity securities. The basis for this strategy is that over time, less liquid equities (small capitalization) will outperform more liquid equities (large capitalization). Roll Yield – Roll Yield investing seeks to capture returns from favoring certain maturities of commodity futures contracts over others. This strategy typically combines offsetting long and short exposures on various sets of individual commodity futures contracts that have different expiration dates. Systematic – Systematic investing seeks to invest in one or more asset classes, or a subset of a specific asset class, to generate the associated market return. For example, the Fund may invest a portion of the portfolio in global equities to generate the market returns associated with that type of investment. Currency Carry – Currency Carry investing seeks to generate returns by investing in higher yielding currencies versus lower yielding currencies. In a carry trade, low interest rate currencies may be sold, and high interest rate currencies may be purchased. As part of the process to identify and isolate specific risk premia and generate returns, the Fund may have both long and short exposure to securities in which it invests with respect to risk premia. The Fund’s exposure to U.S. and non-U.S. investments, which may include emerging markets, will vary based on perceived investment opportunities and the portfolio managers’ global investment outlook. The Fund will make significant use of derivative instruments, which are instruments that have a value derived from or directly linked to an underlying asset, such as equity securities, fixed-income securities, commodities, currencies, interest rates, or market indices. Derivatives will be used to gain exposure to the various asset classes in which the Fund may invest, to generate returns, for hedging purposes (to offset risks associated with an investment, currency exposure, or market conditions), to adjust currency exposure relative to a benchmark index, and to earn income and enhance returns. The Fund may utilize swaps, including equity, interest rate, currency, and total return swaps. The Fund may utilize options and futures, including forward commodity and currency contracts and U.S. Treasury, interest rate, and market index futures. The Fund’s use of options includes options purchased and sold (written). The Fund’s exposure to derivatives will vary and is not limited to those derivatives listed. The Fund’s exposure to derivatives will create a leveraging effect on the portfolio where market exposure exceeds amounts invested. This leverage will vary over time and may at times be significant. The Fund may have a substantial cash position due to margin and collateral requirements related to the Fund’s use of derivatives. Such margin and collateral requirements may limit the Fund’s ability to take advantage of other investment opportunities and may negatively affect the Fund’s ability to achieve its investment objective. The Fund’s equity and fixed-income exposure may be obtained through direct investment in equity and fixed-income securities or through investment in other mutual funds or exchange-traded funds (“ETFs”). The Fund may also utilize exchange-traded notes (“ETNs”). The equity securities in which the Fund invests may involve exposure to common stocks of companies of any size located anywhere in the world, from larger, well-established companies to smaller, emerging growth companies. The fixed-income securities in which the Fund invests may include securities of any maturity and of any credit quality, and may include exposure to government bonds, corporate bonds, convertible bonds, mortgage-backed securities, zero-coupon bonds, and high-yield/high-risk bonds, also known as “junk” bonds. The Fund’s investment in ETFs and ETNs may be used to gain exposure to market indices, a basket of securities, commodities, currencies, or a particular commodity or currency. The Fund’s exposure to the commodity markets, in whole or in part, may be made through investment in a wholly-owned subsidiary of the Fund organized under the laws of the Cayman Islands (the “Subsidiary”), which is generally subject to the same investment policies and restrictions as the Fund. The Subsidiary will invest in commodity-related derivatives such as futures and swaps, ETNs, and other investments such as cash or U.S. Treasuries which may serve as margin or collateral for the Subsidiary’s commodity-linked derivative positions.
Risk [Heading]	rr_RiskHeading	PRINCIPAL INVESTMENT RISKS
Risk Narrative [Text Block]	rr_RiskNarrativeTextBlock	The biggest risk is that the Fund’s returns will vary, and you could lose money. The Fund is designed for long-term investors seeking a portfolio which includes exposure to equity (such as stocks or any other security representing an ownership interest), fixed-income (such as bonds, notes, and debentures), commodities, and currency asset classes, and which involves the use of derivatives. Such investments, and derivatives in particular, tend to be more volatile than many other investment choices. Management Risk. The Fund’s ability to achieve its investment objective depends largely upon the portfolio managers’ successful evaluation of the risks, potential returns, and correlation properties with respect to the various risk premia in which the Fund invests. There is a risk that the returns provided by an individual risk premium may be subject to high volatility and that the portfolio managers’ beliefs about the risk, expected returns and correlation properties of various risk premia may be incorrect. Further, the Fund’s ability to achieve its investment objective also depends on the successful allocation of the Fund’s assets among various risk premia and asset classes, and you could lose money on your investment in the Fund as a result of these allocations. There is also a risk that the Fund’s investments will correlate with the performance of stocks and bonds to a greater degree than anticipated, and the Fund will not meet its investment objective. Finally, Janus Capital does not have prior experience managing a risk premia investment strategy, and there is no guarantee that the investment techniques and analysis used by the Fund’s portfolio managers will produce the desired results. Market Risk. The value of the Fund’s portfolio may decrease if the value of an individual investment, or multiple investments, in the portfolio decreases at the same time. Further, while the Fund’s goal is to produce returns that have a low correlation to the stock and bond markets, you should understand that regardless of how well the Fund’s individual investments perform, the value of the Fund’s portfolio could also decrease if there are deteriorating economic or market conditions. The value of your investment in the Fund may fall, sometimes sharply, in response to changes in the market, and you could lose money. Because the Fund seeks to produce returns that have a low correlation to the returns generated by the stock and bond markets, the Fund may underperform these markets when these markets rise sharply or experience prolonged periods of outperformance. Additionally, the Fund’s performance may be negatively affected during prolonged periods when the returns provided by the risk premia are consistently low. Derivatives Risk. Derivatives can be highly volatile and involve risks in addition to the risks of the underlying referenced securities. Gains or losses from a derivative investment can be substantially greater than the derivative’s original cost, and can therefore involve leverage. Leverage may cause the Fund to be more volatile than if it had not used leverage. Derivatives can be complex instruments and may involve analysis that differs from that required for other investment types used by the Fund. If the value of a derivative does not correlate well with the particular market or other asset class to which the derivative is intended to provide exposure, the derivative may not produce the anticipated result. Derivatives can also reduce the opportunity for gain or result in losses by offsetting positive returns in other investments. Derivatives can be less liquid than other types of investments and entail the risk that the counterparty will default on its payment obligations. If the counterparty to a derivative transaction defaults, the Fund would risk the loss of the net amount of the payments that it contractually is entitled to receive. To the extent the Fund enters into short derivative positions, the Fund may be exposed to risks similar to those associated with short sales, including the risk that the Fund’s losses are theoretically unlimited. Leverage Risk. Engaging in transactions using leverage or those having a leveraging effect subjects the Fund to certain risks. Leverage can magnify the effect of any gains or losses, causing the Fund to be more volatile than if it had not been leveraged. Certain commodity-linked derivative investments may subject the Fund to leveraged market exposure to commodities. In addition, the Fund’s assets that are used as collateral to secure short sale transactions may decrease in value while the short positions are outstanding, which may force the Fund to use its other assets to increase collateral. There is no assurance that a leveraging strategy will be successful. Short Sales Risk. Short sales are speculative transactions and involve special risks, including a greater reliance on the portfolio managers’ ability to accurately anticipate the future value of a security. The Fund will suffer a loss if it sells a security short and the value of the security rises rather than falls. The Fund’s losses are potentially unlimited in a short sale transaction. The use of short sales may also cause the Fund to have higher expenses than those of other funds. In addition, due to the investment process of long and short positions, the Fund may be subject to additional transaction costs that may lower the Fund’s returns. The Fund’s use of short sales may also have a leveraging effect on the Fund’s portfolio. Counterparty Risk. Certain derivative and “over-the-counter” instruments, such as swaps and forwards, are subject to the risk that the other party to a contract will not fulfill its contractual obligations. Commodity-Linked Investments Risk. The Fund may invest, directly or indirectly, in various commodity-linked investments that provide exposure to the commodities markets. Such exposure may subject the Fund to greater volatility than investments in traditional securities. The value of a given commodity-linked derivative investment typically is based upon the price movements of a physical commodity (such as heating oil, livestock, or agricultural products), a commodity futures contract or commodity index, or some other readily measurable economic variable. The value of commodity-linked derivative instruments may therefore be affected by changes in overall market movements, volatility of the underlying benchmark, changes in interest rates, or other factors affecting a particular industry or commodity such as drought, floods, weather, livestock disease, embargoes, tariffs, and international economic, political, and regulatory developments. Subsidiary Risk. By investing in the Subsidiary, the Fund will be indirectly exposed to the risks associated with the Subsidiary’s investments, which are generally similar to those that are permitted to be held by the Fund. The Subsidiary is not registered under the Investment Company Act of 1940, as amended (the “1940 Act”), and is not subject to all of the provisions of the 1940 Act. The Internal Revenue Service (“IRS”) has previously issued a number of private letter rulings to mutual funds (but not the Fund), in which it ruled that income from a fund’s investment in a wholly-owned foreign subsidiary that invests in commodity-linked derivatives, such as the Subsidiary, constitutes qualifying income. The IRS has suspended issuance of any further private letter rulings pending a review of its position. A change in the IRS’ position or changes in the laws of the United States and/or the Cayman Islands could result in the inability of the Fund and/or the Subsidiary to operate as described in the Fund’s Prospectus and the Statement of Additional Information. Such changes could adversely affect the Fund’s ability to meet its investment objective and jeopardize the Fund’s status as a regulated investment company under the U.S. tax code, which in turn may subject the Fund to higher tax rates and/or penalties. Foreign Exposure Risk. The Fund normally has exposure to foreign markets as a result of its investments in foreign securities, including investments in emerging markets, which can be more volatile than the U.S. markets. As a result, its returns and net asset value may be affected to a large degree by fluctuations in currency exchange rates or political or economic conditions in a particular country. In some foreign markets, there may not be protection against failure by other parties to complete transactions. It may not be possible for the Fund to repatriate capital, dividends, interest, and other income from a particular country or governmental entity. In addition, a market swing in one or more countries or regions where the Fund has invested a significant amount of its assets may have a greater effect on the Fund’s performance than it would in a more geographically diversified portfolio. To the extent the Fund invests in foreign debt securities, such investments are sensitive to changes in interest rates. Additionally, investments in securities of foreign governments involve the risk that a foreign government may not be willing or able to pay interest or repay principal when due. The Fund’s exposure to emerging market countries may involve risks greater than, or in addition to, the risks of investing in more developed countries. Eurozone Risk. A number of countries in the European Union (“EU”) have experienced severe economic and financial difficulties. As a result, financial markets in the EU have been subject to extreme volatility and declines in asset values and liquidity. Responses to these financial problems by European governments, central banks, and others, including austerity measures and reforms, may not work, may result in social unrest, and may limit future growth and economic recovery or have other unintended consequences. Further defaults or restructurings by governments and others of their debt could have additional adverse effects on economies, financial markets, and asset valuations around the world. To the extent that the Fund has exposure to European markets or to transactions tied to the value of the euro, these events could negatively affect the value and liquidity of the Fund’s investments. Emerging Markets Risk. The risks of foreign investing mentioned above are heightened when investing in emerging markets. Emerging markets securities involve a number of additional risks, which may result from less government supervision and regulation of business and industry practices (including the potential lack of strict finance and accounting controls and standards), stock exchanges, brokers, and listed companies, making these investments potentially more volatile in price and less liquid than investments in developed securities markets, resulting in greater risk to investors. There is a risk in developing countries that a future economic or political crisis could lead to price controls, forced mergers of companies, expropriation or confiscatory taxation, imposition or enforcement of foreign ownership limits, seizure, nationalization, or creation of government monopolies, any of which may have a detrimental effect on the Fund’s investments. In addition, the Fund’s investments may be denominated in foreign currencies and therefore, changes in the value of a country’s currency compared to the U.S. dollar may affect the value of the Fund’s investments. To the extent that the Fund invests a significant portion of its assets in the securities of issuers in or companies of a single country or region, it is more likely to be impacted by events or conditions affecting that country or region, which could have a negative impact on the Fund’s performance. Some of the risks of investing directly in foreign and emerging market securities may be reduced when the Fund invests indirectly in foreign securities through various other investment vehicles including derivatives, which also involve other risks. Growth Securities Risk. The Fund invests in companies after assessing their growth potential. Securities of companies perceived to be “growth” companies may be more volatile than other stocks and may involve special risks. If the portfolio managers’ perception of a company’s growth potential is not realized, the securities purchased may not perform as expected, reducing the Fund’s returns. In addition, because different types of stocks tend to shift in and out of favor depending on market and economic conditions, “growth” stocks may perform differently from the market as a whole and other types of securities. Fixed-Income Securities Risk. The Fund invests in a variety of fixed-income securities. Typically, the values of fixed-income securities change inversely with prevailing interest rates. Therefore, a fundamental risk of fixed-income securities is interest rate risk, which is the risk that the value of such securities will generally decline as prevailing interest rates rise, which may cause the Fund’s net asset value to likewise decrease. How specific fixed-income securities may react to changes in interest rates will depend on the specific characteristics of each security. Fixed-income securities are also subject to credit risk, prepayment risk, valuation risk, and liquidity risk. Credit risk is the risk that the credit strength of an issuer of a fixed-income security will weaken and/or that the issuer will be unable to make timely principal and interest payments and that the security may go into default. Prepayment risk is the risk that during periods of falling interest rates, certain fixed-income securities with higher interest rates, such as mortgage- and asset-backed securities, may be prepaid by their issuers thereby reducing the amount of interest payments. Valuation risk is the risk that one or more of the fixed-income securities in which the Fund invests are priced differently than the value realized upon such security’s sale. In times of market instability, valuation may be more difficult. Liquidity risk is the risk that fixed-income securities may be difficult or impossible to sell at the time that the portfolio managers would like or at the price the portfolio managers believe the security is currently worth. Mortgage-Backed Securities Risk. Mortgage-backed securities are classified generally as either commercial mortgage-backed securities or residential mortgage-backed securities, each of which is subject to certain specific risks. Mortgage-backed securities tend to be more sensitive to changes in interest rates than other types of debt securities. Investments in mortgage-backed securities are subject to both extension risk, where borrowers extend the duration of their mortgages in times of rising interest rates, and prepayment risk, where borrowers pay off their mortgages sooner than expected in times of declining interest rates. These risks may reduce the Fund’s returns. In addition, investments in mortgage-backed securities, including those comprised of subprime mortgages, may be subject to a higher degree of credit risk, valuation risk, and liquidity risk than various other types of fixed-income securities. Currency Risk. The Fund’s investments and strategies will involve exposure to foreign currencies. Currency risk is the risk that changes in the exchange rate between currencies will adversely affect the value (in U.S. dollar terms) of an investment. As long as the Fund holds a foreign security, its value will be affected by the value of the local currency relative to the U.S. dollar. When the Fund sells a foreign currency denominated security, its value may be worth less in U.S. dollars even if the security increases in value in its home country. U.S. dollar-denominated securities of foreign issuers may also be affected by currency risk, as the value of these securities may also be affected by changes in the issuer’s local currency. Additionally, and as a result of the Fund’s use of currency investment strategies, the Fund’s net currency positions may expose the Fund to losses independent of any securities positions. High-Yield/High-Risk Bond Risk. High-yield/high-risk bonds may be more sensitive than other types of bonds to economic changes, political changes, or adverse developments specific to the company that issued the bond, which may adversely affect their value. Portfolio Turnover Risk. Increased portfolio turnover may result in higher costs, which may have a negative effect on the Fund’s performance. In addition, higher portfolio turnover may result in the acceleration of capital gains and the recognition of greater levels of short-term capital gains, which are taxed at ordinary federal income tax rates when distributed to shareholders. Exchange-Traded Funds Risk. The Fund may invest in ETFs, which are typically open-end investment companies that are traded on a national securities exchange. ETFs typically incur fees, such as investment advisory fees and other operating expenses that are separate from those of the Fund, which will be indirectly paid by the Fund. As a result, the cost of investing in the Fund may be higher than the cost of investing directly in ETFs and may be higher than other mutual funds that invest directly in stocks and bonds. Further, the price movement of an ETF may fluctuate against the underlying securities or commodities it tracks and may result in a loss. Because the value of ETF shares depends on the demand in the market, the Fund may not be able to purchase or sell an ETF at the most optimal time, which could adversely affect the Fund’s performance. The ETFs in which the Fund invests are subject to specific risks, depending on the investment strategy of the ETF. In turn, the Fund will be subject to substantially the same risks as those associated with direct exposure to the securities or commodities held by the ETF. Because the Fund may invest in a broad range of ETFs, such risks may include, but are not limited to, leverage risk, foreign exposure risk, fixed-income risk, and commodity-linked investments risk. Exchange-Traded Notes Risk. The Fund may invest in ETNs, which are debt securities whose returns are linked to a particular index. ETNs are typically linked to the performance of a commodities index that reflects the potential return on unleveraged investments in futures contracts of physical commodities, plus a specified rate of interest that could be earned on cash collateral. ETNs are subject to credit risk and counterparty risk. The value of an ETN may vary and may be influenced by time to maturity, level of supply and demand for the ETN, volatility and lack of liquidity in underlying commodities markets, changes in the applicable interest rates, changes in the issuer’s credit rating, and economic, legal, political, or geographic events that affect the referenced commodity. When the Fund invests in ETNs it will bear its proportionate share of any fees and expenses borne by the ETN. There may be restrictions on the Fund’s right to redeem its investment in an ETN, which is meant to be held until maturity. The Fund’s decision to sell its ETN holdings may be limited by the availability of a secondary market. Nondiversification Risk. Although the Fund seeks diverse sources of potential return or risk premia, the Fund is classified as nondiversified under the 1940 Act. This gives the Fund’s portfolio managers more flexibility to hold larger positions in a smaller number of securities. As a result, an increase or decrease in the value of a single security held by the Fund may have a greater impact on the Fund’s net asset value and total return. An investment in the Fund is not a bank deposit and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency.
Risk Lose Money [Text]	rr_RiskLoseMoney	The biggest risk is that the Fund’s returns will vary, and you could lose money.
Risk Nondiversified Status [Text]	rr_RiskNondiversifiedStatus	Nondiversification Risk. Although the Fund seeks diverse sources of potential return or risk premia, the Fund is classified as nondiversified under the 1940 Act. This gives the Fund’s portfolio managers more flexibility to hold larger positions in a smaller number of securities. As a result, an increase or decrease in the value of a single security held by the Fund may have a greater impact on the Fund’s net asset value and total return.
Risk Not Insured Depository Institution [Text]	rr_RiskNotInsuredDepositoryInstitution	An investment in the Fund is not a bank deposit and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency.
Bar Chart and Performance Table [Heading]	rr_BarChartAndPerformanceTableHeading	PERFORMANCE INFORMATION
Performance Narrative [Text Block]	rr_PerformanceNarrativeTextBlock	The Fund does not have a full calendar year of operations. Performance information for certain periods is included in the Fund’s first annual and/or semiannual report.
Performance One Year or Less [Text]	rr_PerformanceOneYearOrLess	The Fund does not have a full calendar year of operations.
Janus Diversified Alternatives Fund | Class A, C, S, I, N, T Shares | Class A
Risk/Return:	rr_RiskReturnAbstract
Shareholder Fees Column [Text]	rr_ShareholderFeesColumnName	Class A
Maximum Sales Charge (load) Imposed on Purchases (as a percentage of offering price)	rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice	5.75%
Maximum Deferred Sales Charge (load) (as a percentage of the lower of original purchase price or redemption proceeds)	rr_MaximumDeferredSalesChargeOverOther	none
Operating Expenses Column [Text]	rr_OperatingExpensesColumnName	Class A
Management Fees of the Fund and the Subsidiary	rr_ManagementFeesOverAssets	1.00%	[1]
Distribution/Service (12b-1) Fees	rr_DistributionAndService12b1FeesOverAssets	0.25%
Other Expenses of the Fund	rr_Component1OtherExpensesOverAssets	0.61%	[2]
Other Expenses of the Subsidiary	rr_Component2OtherExpensesOverAssets	0.02%
Other Expenses	rr_OtherExpensesOverAssets	0.63%
Total Annual Fund Operating Expenses	rr_ExpensesOverAssets	1.88%	[3]
Fee Waiver	rr_FeeWaiverOrReimbursementOverAssets	0.35%	[3]
Total Annual Fund Operating Expenses After Fee Waiver	rr_NetExpensesOverAssets	1.53%	[3]
Expense Example, By Year, Column [Text]	rr_ExpenseExampleByYearColumnName	Class A Shares
1 Year	rr_ExpenseExampleYear01	755
3 Years	rr_ExpenseExampleYear03	1,132
5 Years	rr_ExpenseExampleYear05	1,533
10 Years	rr_ExpenseExampleYear10	2,649
Expense Example, No Redemption, By Year, Column [Text]	rr_ExpenseExampleNoRedemptionByYearColumnName	Class A Shares
1 Year	rr_ExpenseExampleNoRedemptionYear01	755
3 Years	rr_ExpenseExampleNoRedemptionYear03	1,132
5 Years	rr_ExpenseExampleNoRedemptionYear05	1,533
10 Years	rr_ExpenseExampleNoRedemptionYear10	2,649
Janus Diversified Alternatives Fund | Class A, C, S, I, N, T Shares | Class C
Risk/Return:	rr_RiskReturnAbstract
Shareholder Fees Column [Text]	rr_ShareholderFeesColumnName	Class C
Maximum Sales Charge (load) Imposed on Purchases (as a percentage of offering price)	rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice	none
Maximum Deferred Sales Charge (load) (as a percentage of the lower of original purchase price or redemption proceeds)	rr_MaximumDeferredSalesChargeOverOther	1.00%
Operating Expenses Column [Text]	rr_OperatingExpensesColumnName	Class C
Management Fees of the Fund and the Subsidiary	rr_ManagementFeesOverAssets	1.00%	[1]
Distribution/Service (12b-1) Fees	rr_DistributionAndService12b1FeesOverAssets	1.00%
Other Expenses of the Fund	rr_Component1OtherExpensesOverAssets	0.74%	[2]
Other Expenses of the Subsidiary	rr_Component2OtherExpensesOverAssets	0.02%
Other Expenses	rr_OtherExpensesOverAssets	0.76%
Total Annual Fund Operating Expenses	rr_ExpensesOverAssets	2.76%	[3]
Fee Waiver	rr_FeeWaiverOrReimbursementOverAssets	0.47%	[3]
Total Annual Fund Operating Expenses After Fee Waiver	rr_NetExpensesOverAssets	2.29%	[3]
Expense Example, By Year, Column [Text]	rr_ExpenseExampleByYearColumnName	Class C Shares
1 Year	rr_ExpenseExampleYear01	379
3 Years	rr_ExpenseExampleYear03	856
5 Years	rr_ExpenseExampleYear05	1,459
10 Years	rr_ExpenseExampleYear10	3,090
Expense Example, No Redemption, By Year, Column [Text]	rr_ExpenseExampleNoRedemptionByYearColumnName	Class C Shares
1 Year	rr_ExpenseExampleNoRedemptionYear01	279
3 Years	rr_ExpenseExampleNoRedemptionYear03	856
5 Years	rr_ExpenseExampleNoRedemptionYear05	1,459
10 Years	rr_ExpenseExampleNoRedemptionYear10	3,090
Janus Diversified Alternatives Fund | Class A, C, S, I, N, T Shares | Class S
Risk/Return:	rr_RiskReturnAbstract
Shareholder Fees Column [Text]	rr_ShareholderFeesColumnName	Class S
Maximum Sales Charge (load) Imposed on Purchases (as a percentage of offering price)	rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice	none
Maximum Deferred Sales Charge (load) (as a percentage of the lower of original purchase price or redemption proceeds)	rr_MaximumDeferredSalesChargeOverOther	none
Operating Expenses Column [Text]	rr_OperatingExpensesColumnName	Class S
Management Fees of the Fund and the Subsidiary	rr_ManagementFeesOverAssets	1.00%	[1]
Distribution/Service (12b-1) Fees	rr_DistributionAndService12b1FeesOverAssets	0.25%
Other Expenses of the Fund	rr_Component1OtherExpensesOverAssets	0.74%	[2]
Other Expenses of the Subsidiary	rr_Component2OtherExpensesOverAssets	0.02%
Other Expenses	rr_OtherExpensesOverAssets	0.76%
Total Annual Fund Operating Expenses	rr_ExpensesOverAssets	2.01%	[3]
Fee Waiver	rr_FeeWaiverOrReimbursementOverAssets	0.24%	[3]
Total Annual Fund Operating Expenses After Fee Waiver	rr_NetExpensesOverAssets	1.77%	[3]
Expense Example, By Year, Column [Text]	rr_ExpenseExampleByYearColumnName	Class S Shares
1 Year	rr_ExpenseExampleYear01	204
3 Years	rr_ExpenseExampleYear03	630
5 Years	rr_ExpenseExampleYear05	1,083
10 Years	rr_ExpenseExampleYear10	2,338
Expense Example, No Redemption, By Year, Column [Text]	rr_ExpenseExampleNoRedemptionByYearColumnName	Class S Shares
1 Year	rr_ExpenseExampleNoRedemptionYear01	204
3 Years	rr_ExpenseExampleNoRedemptionYear03	630
5 Years	rr_ExpenseExampleNoRedemptionYear05	1,083
10 Years	rr_ExpenseExampleNoRedemptionYear10	2,338
Janus Diversified Alternatives Fund | Class A, C, S, I, N, T Shares | Class I
Risk/Return:	rr_RiskReturnAbstract
Shareholder Fees Column [Text]	rr_ShareholderFeesColumnName	Class I
Maximum Sales Charge (load) Imposed on Purchases (as a percentage of offering price)	rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice	none
Maximum Deferred Sales Charge (load) (as a percentage of the lower of original purchase price or redemption proceeds)	rr_MaximumDeferredSalesChargeOverOther	none
Operating Expenses Column [Text]	rr_OperatingExpensesColumnName	Class I
Management Fees of the Fund and the Subsidiary	rr_ManagementFeesOverAssets	1.00%	[1]
Distribution/Service (12b-1) Fees	rr_DistributionAndService12b1FeesOverAssets	none
Other Expenses of the Fund	rr_Component1OtherExpensesOverAssets	0.51%	[2]
Other Expenses of the Subsidiary	rr_Component2OtherExpensesOverAssets	0.02%
Other Expenses	rr_OtherExpensesOverAssets	0.53%
Total Annual Fund Operating Expenses	rr_ExpensesOverAssets	1.53%	[3]
Fee Waiver	rr_FeeWaiverOrReimbursementOverAssets	0.26%	[3]
Total Annual Fund Operating Expenses After Fee Waiver	rr_NetExpensesOverAssets	1.27%	[3]
Expense Example, By Year, Column [Text]	rr_ExpenseExampleByYearColumnName	Class I Shares
1 Year	rr_ExpenseExampleYear01	156
3 Years	rr_ExpenseExampleYear03	483
5 Years	rr_ExpenseExampleYear05	834
10 Years	rr_ExpenseExampleYear10	1,824
Expense Example, No Redemption, By Year, Column [Text]	rr_ExpenseExampleNoRedemptionByYearColumnName	Class I Shares
1 Year	rr_ExpenseExampleNoRedemptionYear01	156
3 Years	rr_ExpenseExampleNoRedemptionYear03	483
5 Years	rr_ExpenseExampleNoRedemptionYear05	834
10 Years	rr_ExpenseExampleNoRedemptionYear10	1,824
Janus Diversified Alternatives Fund | Class A, C, S, I, N, T Shares | Class N
Risk/Return:	rr_RiskReturnAbstract
Shareholder Fees Column [Text]	rr_ShareholderFeesColumnName	Class N
Maximum Sales Charge (load) Imposed on Purchases (as a percentage of offering price)	rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice	none
Maximum Deferred Sales Charge (load) (as a percentage of the lower of original purchase price or redemption proceeds)	rr_MaximumDeferredSalesChargeOverOther	none
Operating Expenses Column [Text]	rr_OperatingExpensesColumnName	Class N
Management Fees of the Fund and the Subsidiary	rr_ManagementFeesOverAssets	1.00%	[1]
Distribution/Service (12b-1) Fees	rr_DistributionAndService12b1FeesOverAssets	none
Other Expenses of the Fund	rr_Component1OtherExpensesOverAssets	0.51%	[2]
Other Expenses of the Subsidiary	rr_Component2OtherExpensesOverAssets	0.02%
Other Expenses	rr_OtherExpensesOverAssets	0.53%
Total Annual Fund Operating Expenses	rr_ExpensesOverAssets	1.53%	[3]
Fee Waiver	rr_FeeWaiverOrReimbursementOverAssets	0.26%	[3]
Total Annual Fund Operating Expenses After Fee Waiver	rr_NetExpensesOverAssets	1.27%	[3]
Expense Example, By Year, Column [Text]	rr_ExpenseExampleByYearColumnName	Class N Shares
1 Year	rr_ExpenseExampleYear01	156
3 Years	rr_ExpenseExampleYear03	483
5 Years	rr_ExpenseExampleYear05	834
10 Years	rr_ExpenseExampleYear10	1,824
Expense Example, No Redemption, By Year, Column [Text]	rr_ExpenseExampleNoRedemptionByYearColumnName	Class N Shares
1 Year	rr_ExpenseExampleNoRedemptionYear01	156
3 Years	rr_ExpenseExampleNoRedemptionYear03	483
5 Years	rr_ExpenseExampleNoRedemptionYear05	834
10 Years	rr_ExpenseExampleNoRedemptionYear10	1,824
Janus Diversified Alternatives Fund | Class A, C, S, I, N, T Shares | Class T
Risk/Return:	rr_RiskReturnAbstract
Shareholder Fees Column [Text]	rr_ShareholderFeesColumnName	Class T
Maximum Sales Charge (load) Imposed on Purchases (as a percentage of offering price)	rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice	none
Maximum Deferred Sales Charge (load) (as a percentage of the lower of original purchase price or redemption proceeds)	rr_MaximumDeferredSalesChargeOverOther	none
Operating Expenses Column [Text]	rr_OperatingExpensesColumnName	Class T
Management Fees of the Fund and the Subsidiary	rr_ManagementFeesOverAssets	1.00%	[1]
Distribution/Service (12b-1) Fees	rr_DistributionAndService12b1FeesOverAssets	none
Other Expenses of the Fund	rr_Component1OtherExpensesOverAssets	0.74%	[2]
Other Expenses of the Subsidiary	rr_Component2OtherExpensesOverAssets	0.02%
Other Expenses	rr_OtherExpensesOverAssets	0.76%
Total Annual Fund Operating Expenses	rr_ExpensesOverAssets	1.76%	[3]
Fee Waiver	rr_FeeWaiverOrReimbursementOverAssets	0.24%	[3]
Total Annual Fund Operating Expenses After Fee Waiver	rr_NetExpensesOverAssets	1.52%	[3]
Expense Example, By Year, Column [Text]	rr_ExpenseExampleByYearColumnName	Class T Shares
1 Year	rr_ExpenseExampleYear01	179
3 Years	rr_ExpenseExampleYear03	554
5 Years	rr_ExpenseExampleYear05	954
10 Years	rr_ExpenseExampleYear10	2,073
Expense Example, No Redemption, By Year, Column [Text]	rr_ExpenseExampleNoRedemptionByYearColumnName	Class T Shares
1 Year	rr_ExpenseExampleNoRedemptionYear01	179
3 Years	rr_ExpenseExampleNoRedemptionYear03	554
5 Years	rr_ExpenseExampleNoRedemptionYear05	954
10 Years	rr_ExpenseExampleNoRedemptionYear10	$ 2,073

[1] The Fund may invest in commodity-linked investments through a wholly-owned subsidiary of the Fund that invests in commodity-linked investments. Janus Capital has contractually agreed that to the extent the Fund invests in the subsidiary, it shall not collect advisory fees from the Fund in an amount equal to the fee it collects from the subsidiary. The management fee waiver arrangement may not be discontinued by Janus Capital as long as its contract with the subsidiary is in place.

[2] Other Expenses are based on the estimated expenses that the Fund expects to incur.

[3] Janus Capital has contractually agreed to waive its investment advisory fee and/or reimburse Fund expenses to the extent that the Fund's total annual fund operating expenses, which include the other expenses of the subsidiary shown above (excluding the distribution and shareholder servicing fees – applicable to Class A Shares, Class C Shares, and Class S Shares; administrative services fees payable pursuant to the Transfer Agency Agreement; brokerage commissions; interest; dividends; taxes; acquired fund fees and expenses; and extraordinary expenses) exceed 1.25% until at least November 1, 2014. The contractual waiver may be terminated or modified prior to this date only at the discretion of the Board of Trustees. For a period of three years subsequent to the Fund's commencement of operations (December 28, 2012) or until the Fund's assets exceed the first breakpoint in the investment advisory fee schedule, whichever occurs first, Janus Capital may recover from the Fund fees and expenses previously waived or reimbursed, which could then be considered a deferral, if the Fund's expense ratio, including recovered expenses, falls below the expense limit.

XML

Label	Element	Value
Risk/Return:	rr_RiskReturnAbstract
Registrant Name	dei_EntityRegistrantName	JANUS INVESTMENT FUND
Prospectus Date	rr_ProspectusDate	Oct. 28, 2013
Janus Global Allocation Fund - Conservative | Class D Shares
Risk/Return:	rr_RiskReturnAbstract
Risk/Return [Heading]	rr_RiskReturnHeading	FUND SUMMARY Janus Global Allocation Fund – Conservative (formerly named Janus Conservative Allocation Fund)
Objective [Heading]	rr_ObjectiveHeading	INVESTMENT OBJECTIVE
Objective, Primary [Text Block]	rr_ObjectivePrimaryTextBlock	Janus Global Allocation Fund – Conservative seeks total return through a primary emphasis on income with a secondary emphasis on growth of capital.
Expense [Heading]	rr_ExpenseHeading	FEES AND EXPENSES OF THE FUND
Expense Narrative [Text Block]	rr_ExpenseNarrativeTextBlock	This table describes the fees and expenses that you may pay if you buy and hold Shares of the Fund.
Operating Expenses Caption [Text]	rr_OperatingExpensesCaption	ANNUAL FUND OPERATING EXPENSES (expenses that you pay each year as a percentage of the value of your investment)
Portfolio Turnover [Heading]	rr_PortfolioTurnoverHeading	Portfolio Turnover:
Portfolio Turnover [Text Block]	rr_PortfolioTurnoverTextBlock	The Fund pays transaction costs, such as commissions, when it buys and sells securities (or “turns over” its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when Fund shares are held in a taxable account. These costs, which are not reflected in annual fund operating expenses or in the Example, affect the Fund’s performance. During the most recent fiscal year, the Fund’s portfolio turnover rate was 69% of the average value of its portfolio.
Portfolio Turnover, Rate	rr_PortfolioTurnoverRate	69.00%
Expense Example [Heading]	rr_ExpenseExampleHeading	EXAMPLE:
Expense Example by Year [Heading]	rr_ExpenseExampleByYearHeading	The Example assumes that you invest $10,000 in the Fund for the time periods indicated, reinvest all dividends and distributions, and then redeem all of your Shares at the end of each period. The Example also assumes that your investment has a 5% return each year and that the Fund’s operating expenses (including the operating expenses of the underlying funds) remain the same. Although your actual costs may be higher or lower, based on these assumptions your costs would be:
Expense Example Narrative [Text Block]	rr_ExpenseExampleNarrativeTextBlock	The Example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds.
Strategy [Heading]	rr_StrategyHeading	PRINCIPAL INVESTMENT STRATEGIES
Strategy Narrative [Text Block]	rr_StrategyNarrativeTextBlock	The Fund seeks to achieve its investment objective by investing in other Janus mutual funds (“underlying funds”) that represent a variety of asset classes and investment styles and provide exposure to issuers that are economically tied to countries throughout the world. Through its investments in underlying funds, the Fund invests in issuers from several different countries and may, under unusual circumstances, be invested in a single country. As a result, the Fund normally will have approximately 40% of its net assets allocated to non-U.S. investments. The Fund may also have significant exposure to emerging markets. The Fund pursues this objective by investing in a diversified portfolio of underlying funds, resulting in an allocation of the Fund’s investments that normally provides exposure of approximately 55% to fixed-income securities and money market instruments, 40% to equity investments, and 5% to alternative investments. The target allocation and the allocation of the Fund’s assets among underlying funds are based on quantitative and qualitative analysis. Because it invests in other funds, the Fund is considered a “fund of funds.” The Fund’s asset allocation is intended to diversify investments throughout the world among equity investments, fixed-income securities, cash equivalents, and alternative investments. The portfolio manager determines the overall composition of the Fund, oversees the investment process, and is responsible for the day-to-day management of the Fund. The portfolio manager continually monitors asset class allocations and periodically rebalances the Fund’s investments in the underlying funds. The portfolio manager also regularly reviews the allocation of Fund assets in the underlying funds and may modify the underlying funds’ weightings or substitute other underlying funds to emphasize and mitigate risk exposures that may arise as a result of the implementation of the allocations. An independent asset allocation service provides evaluations of asset allocations that the portfolio manager may use in implementing the allocations among the underlying funds. Additionally, the portfolio manager consults with a committee (the “Janus Global Allocation Committee”) to regularly review the broad market, macroeconomic conditions and other global financial factors that may impact the Fund’s allocation of assets among the underlying funds and asset classes. The Janus Global Allocation Committee is comprised of investment professionals of Janus Capital and may also include investment professionals of Janus Capital’s affiliated investment advisers. The portfolio manager and Janus Global Allocation Committee normally meet on a quarterly basis. The portfolio manager may change the Fund’s asset class allocations, the underlying funds, an underlying fund’s asset category, or weightings among asset classes or underlying funds without prior shareholder notice. The Fund will normally allocate approximately 55% of its investments to underlying bond funds and money market instruments, approximately 40% of its investments to underlying funds that provide varying exposure to common stocks of large U.S.-based companies, small- to mid-capitalization companies, and international companies (including those with exposure to emerging markets), and approximately 5% of its investments to underlying funds that seek returns uncorrelated with the returns of stocks and bonds by providing exposure to alternative investments and alternative investment strategies. Refer to Appendix A in this Prospectus for a brief description of the investment strategies of each of the currently available underlying funds. When market conditions dictate a more defensive strategy, the Fund or an underlying fund may temporarily hold cash or invest its assets in temporary investments. In that case, the Fund may take positions that are inconsistent with its investment objective. As a result, the Fund may not achieve its investment objective.
Risk [Heading]	rr_RiskHeading	PRINCIPAL INVESTMENT RISKS
Risk Narrative [Text Block]	rr_RiskNarrativeTextBlock	The biggest risk is that the Fund’s returns will vary, and you could lose money. The Fund is designed for long-term investors seeking income and, to a lesser extent, growth of capital. Investments in a portfolio with common stock and alternative investment exposure tend to be more volatile than many other investment choices. Main Risks Associated with the Fund Allocation Risk. The Fund’s ability to achieve its investment objective depends largely upon the portfolio manager’s allocation of assets among the underlying funds and other securities, using the optimization process (a process that utilizes quantitative analysis of a number of factors, such as historical risk, performance, fund classifications, and the relationship among underlying funds) and the judgment of the portfolio manager. You could lose money on your investment in the Fund as a result of these allocations. The Fund will typically invest in a number of different underlying funds; however, to the extent that the Fund invests a significant portion of its assets in a single underlying fund, it will be more sensitive to the risks associated with that fund and any investments in which that fund focuses. Affiliated Fund Risk. Janus Capital has the authority to select and substitute underlying affiliated mutual funds. The fees paid to Janus Capital by some Janus mutual funds are generally higher than the fees paid to Janus Capital by the Fund or by other funds and share classes available for investment by the Fund. These conditions may create a conflict of interest when selecting underlying affiliated mutual funds and share classes for investment. Janus Capital, however, is a fiduciary to the Fund and its shareholders and is legally obligated to act in their best interest when selecting underlying affiliated mutual funds. Main Risks Associated with the Underlying Funds and Securities The biggest risk is that the underlying funds’ returns will vary, and you could lose money. Fixed-Income Securities Risk. Approximately 55% of the Fund’s assets are allocated to fixed-income securities through investments in underlying funds. Typically, the values of fixed-income securities change inversely with prevailing interest rates. Therefore, a fundamental risk of fixed-income securities is interest rate risk, which is the risk that the value of such securities will generally decline as prevailing interest rates rise, which may cause an underlying fund’s net asset value to likewise decrease. How specific fixed-income securities may react to changes in interest rates will depend on the specific characteristics of each security. Fixed-income securities are also subject to credit risk, prepayment risk, valuation risk, and liquidity risk. Credit risk is the risk that the credit strength of an issuer of a fixed-income security will weaken and/or that the issuer will be unable to make timely principal and interest payments and that the security may go into default. Prepayment risk is the risk that during periods of falling interest rates, certain fixed-income securities with higher interest rates, such as mortgage- and asset-backed securities, may be prepaid by their issuers thereby reducing the amount of interest payments. Valuation risk is the risk that one or more of the fixed-income securities in which an underlying fund invests are priced differently than the value realized upon such security’s sale. In times of market instability, valuation may be more difficult. Liquidity risk is the risk that fixed-income securities may be difficult or impossible to sell at the time that an underlying fund’s portfolio manager would like or at the price the portfolio manager believes the security is currently worth. Mortgage-Backed Securities Risk. Mortgage-backed securities are classified generally as either commercial mortgage-backed securities or residential mortgage-backed securities, each of which is subject to certain specific risks. Mortgage-backed securities tend to be more sensitive to changes in interest rates than other types of debt securities. Investments in mortgage-backed securities are subject to both extension risk, where borrowers extend the duration of their mortgages in times of rising interest rates, and prepayment risk, where borrowers pay off their mortgages sooner than expected in times of declining interest rates. These risks may reduce the Fund’s returns. In addition, investments in mortgage-backed securities, including those comprised of subprime mortgages, may be subject to a higher degree of credit risk, valuation risk, and liquidity risk than various other types of fixed-income securities. Market Risk. Approximately 40% of the Fund’s assets are allocated to equity investments through investments in underlying funds. The value of an underlying fund’s portfolio may decrease if the value of an individual company or security, or multiple companies or securities, in the portfolio decreases or if a portfolio manager’s belief about a company’s intrinsic worth is incorrect. Further, regardless of how well individual companies or securities perform, the value of an underlying fund’s portfolio could also decrease if there are deteriorating economic or market conditions. It is important to understand that the value of your investment may fall, sometimes sharply, in response to changes in the market, and you could lose money. Foreign Exposure Risk. Certain underlying funds may have significant exposure to foreign markets as a result of their investments in foreign securities, including investments in emerging markets, which can be more volatile than the U.S. markets. As a result, an underlying fund’s returns and net asset value may be affected to a large degree by fluctuations in currency exchange rates or political or economic conditions in a particular country. A market swing in one or more countries or regions where an underlying fund has invested a significant amount of its assets may have a greater effect on an underlying fund’s performance than it would in a more geographically diversified portfolio. An underlying fund’s investments in emerging market countries may involve risks greater than, or in addition to, the risks of investing in more developed countries. Emerging Markets Risk. The risks of foreign investing mentioned above are heightened when investing in emerging markets. Emerging markets securities involve a number of additional risks, which may result from less government supervision and regulation of business and industry practices (including the potential lack of strict finance and accounting controls and standards), stock exchanges, brokers, and listed companies, making these investments potentially more volatile in price and less liquid than investments in developed securities markets, resulting in greater risk to investors. In addition, an underlying fund’s investments may be denominated in foreign currencies and therefore, changes in the value of a country’s currency compared to the U.S. dollar may affect the value of an underlying fund’s investments. To the extent that an underlying fund invests a significant portion of its assets in the securities of issuers in or companies of a single country or region, it is more likely to be impacted by events or conditions affecting that country or region, which could have a negative impact on the Fund’s performance. Some of the risks of investing directly in foreign and emerging market securities may be reduced when an underlying fund invests indirectly in foreign securities through various other investment vehicles including derivatives, which also involve other risks. Sovereign Debt Risk. An underlying fund may invest in U.S. and foreign government debt securities (“sovereign debt”). Investments in U.S. sovereign debt are considered low risk. However, investments in non-U.S. sovereign debt can involve a high degree of risk, including the risk that the governmental entity that controls the repayment of sovereign debt may not be willing or able to repay the principal and/or to pay the interest on its sovereign debt in a timely manner. A sovereign debtor’s willingness or ability to satisfy its debt obligation may be affected by various factors including, but not limited to, its cash flow situation, the extent of its foreign currency reserves, the availability of foreign exchange when a payment is due, and the relative size of its debt position in relation to its economy as a whole. In the event of default, there may be limited or no legal remedies for collecting sovereign debt and there may be no bankruptcy proceedings through which the underlying fund may collect all or part of the sovereign debt that a governmental entity has not repaid. Alternative Investments Allocation Risk. Approximately 5% of the Fund’s assets are allocated to alternative investments through investments in underlying funds that invest in alternative investment strategies. In connection with the Fund’s allocation to alternative investments, the Fund may invest in a Janus underlying fund, Janus Diversified Alternatives Fund, which seeks returns uncorrelated with the returns generated by investments in stocks and bonds. In addition, as part of its alternative investments allocation, the Fund may invest in Janus Global Real Estate Fund. Janus Diversified Alternatives Fund’s ability to achieve its investment objective depends largely upon the successful evaluation of the risk, potential returns, and correlation properties with respect to its investments. There is a risk that the returns provided by alternative investments may be subject to high volatility and that an underlying fund’s portfolio manager’s beliefs about the expected returns, risk and correlation properties of one or more of an underlying fund’s investments may be incorrect. There is also a risk that an underlying fund’s investments will correlate with the performance of stocks and bonds to a greater degree than anticipated. Janus Capital does not have prior experience managing the investment strategy of Janus Diversified Alternatives Fund, and there is no guarantee that the investment techniques and analysis used by the underlying fund’s portfolio managers will produce the desired results. All of these factors may negatively affect your investment in the Fund and you could lose money. Investment in the underlying funds also involves derivatives, counterparty, leverage, real estate-related, and commodity-linked investment risks. Counterparty Risk. Certain derivative and “over-the-counter” instruments, such as swaps and forwards, are subject to the risk that the other party to a contract will not fulfill its contractual obligations. Commodity-Linked Investments Risk. Certain underlying funds may invest in derivatives that have exposure to the commodities markets. Such exposure may subject an underlying fund to greater volatility than investments in traditional securities. The value of a commodity-linked derivative investment typically is based upon the price movements of a physical commodity (such as heating oil, livestock, or agricultural products), a commodity futures contract or commodity index, or some other readily measurable economic variable. The value of commodity-linked derivative instruments may therefore be affected by changes in overall market movements, volatility of the underlying benchmark, changes in interest rates, or other factors affecting a particular industry or commodity such as drought, floods, weather, livestock disease, embargoes, tariffs, and international economic, political, and regulatory developments. Derivatives Risk. Certain underlying funds may invest in derivatives. Derivatives can be highly volatile and involve risks in addition to the risks of the underlying referenced securities. Gains or losses from a derivative investment can be substantially greater than the derivative’s original cost, and can therefore involve leverage. Leverage may cause an underlying fund to be more volatile than if it had not used leverage. Derivatives can be less liquid than other types of investments and entail the risk that the counterparty will default on its payment obligations. Exchange-Traded Funds Risk. Certain underlying funds may purchase shares of exchange-traded funds (“ETFs”) to gain exposure to a particular portion of the market. ETFs are pooled investment vehicles, which may be managed or unmanaged, that generally seek to track the performance of a specific index. ETFs are traded on an exchange at market prices that may vary from the net asset value of their underlying investments. When an underlying fund invests in an ETF, in addition to directly bearing the expenses associated with its own operations, it will bear a pro rata portion of the ETF’s expenses. ETFs have certain inherent risks generally associated with investments in a portfolio of securities in which the ETF is invested, including the risk that the general level of stock prices may decline, thereby adversely affecting the value of each unit of the ETF. ETFs also involve the risk that an active trading market for an ETF’s shares may not develop or be maintained. Exchange-Traded Notes Risk. Certain underlying funds may invest in exchange-traded notes (“ETNs”), which are debt securities whose returns are linked to a particular index. ETNs are typically linked to the performance of a commodities index that reflects the potential return on unleveraged investments in futures contracts of physical commodities, plus a specified rate of interest that could be earned on cash collateral. ETNs are subject to credit risk and counterparty risk. The value of an ETN may vary and may be influenced by time to maturity, level of supply and demand for the ETN, volatility and lack of liquidity in underlying commodities markets, changes in the applicable interest rates, changes in the issuer’s credit rating, and economic, legal, political, or geographic events that affect the referenced commodity. When an underlying fund invests in ETNs it will bear its proportionate share of any fees and expenses borne by the ETN. There may be restrictions on an underlying fund’s right to redeem its investment in an ETN, which is meant to be held until maturity. An underlying fund’s decision to sell its ETN holdings may be limited by the availability of a secondary market. An investment in the Fund is not a bank deposit and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency.
Risk Lose Money [Text]	rr_RiskLoseMoney	The biggest risk is that the Fund’s returns will vary, and you could lose money.
Risk Not Insured Depository Institution [Text]	rr_RiskNotInsuredDepositoryInstitution	An investment in the Fund is not a bank deposit and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency.
Bar Chart and Performance Table [Heading]	rr_BarChartAndPerformanceTableHeading	PERFORMANCE INFORMATION
Performance Narrative [Text Block]	rr_PerformanceNarrativeTextBlock	The following information provides some indication of the risks of investing in the Fund by showing how the Fund’s performance has varied over time. Class D Shares of the Fund commenced operations on February 16, 2010, as a result of the restructuring of Class J Shares, the predecessor share class. The performance shown for Class D Shares for periods prior to February 16, 2010, reflects the performance of the Fund’s former Class J Shares, calculated using the fees and expenses in effect during the periods shown, net of any applicable fee and expense limitations or waivers. If Class D Shares of the Fund had been available during periods prior to February 16, 2010, the performance shown may have been different. The performance shown for periods following the Fund’s commencement of Class D Shares reflects the fees and expenses of Class D Shares, net of any applicable fee and expense limitations or waivers. The bar chart depicts the change in performance from year to year during the periods indicated. Performance information for each underlying fund is available in its prospectus and/or the most recent annual or semiannual report. The table compares the Fund’s average annual returns for the periods indicated to broad-based securities market indices. The indices are not actively managed and are not available for direct investment. All figures assume reinvestment of dividends and distributions. For certain periods, the Fund’s performance reflects the effect of expense waivers. Without the effect of these expense waivers, the performance shown would have been lower. The Fund’s past performance (before and after taxes) does not necessarily indicate how it will perform in the future. Updated performance information is available at janus.com/allfunds or by calling 1-800-525-3713.
Performance Information Illustrates Variability of Returns [Text]	rr_PerformanceInformationIllustratesVariabilityOfReturns	The following information provides some indication of the risks of investing in the Fund by showing how the Fund’s performance has varied over time. The bar chart depicts the change in performance from year to year during the periods indicated.
Performance Additional Market Index [Text]	rr_PerformanceAdditionalMarketIndex	The table compares the Fund’s average annual returns for the periods indicated to broad-based securities market indices. The indices are not actively managed and are not available for direct investment. All figures assume reinvestment of dividends and distributions.
Performance Availability Phone [Text]	rr_PerformanceAvailabilityPhone	1-800-525-3713
Performance Availability Website Address [Text]	rr_PerformanceAvailabilityWebSiteAddress	janus.com/allfunds
Performance Past Does Not Indicate Future [Text]	rr_PerformancePastDoesNotIndicateFuture	The Fund’s past performance (before and after taxes) does not necessarily indicate how it will perform in the future.
Bar Chart [Heading]	rr_BarChartHeading	Annual Total Returns for Class D Shares (calendar year-end)
Bar Chart Closing [Text Block]	rr_BarChartClosingTextBlock	Best Quarter:  Second Quarter 2009  10.64%          Worst Quarter:  Third Quarter 2008  −6.58%
Year to Date Return, Label	rr_YearToDateReturnLabel	The Fund’s year-to-date return as of the calendar quarter ended September 30, 2013 was 6.60%.
Performance Table Heading	rr_PerformanceTableHeading	Average Annual Total Returns (periods ended 12/31/12)
Performance Table Uses Highest Federal Rate	rr_PerformanceTableUsesHighestFederalRate	After-tax returns are calculated using the historically highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes.
Performance Table Not Relevant to Tax Deferred	rr_PerformanceTableNotRelevantToTaxDeferred	Actual after-tax returns depend on your individual tax situation and may differ from those shown in the preceding table. The after-tax return information shown above does not apply to Fund shares held through a tax-deferred account, such as a 401(k) plan or an IRA.
Performance Table Narrative	rr_PerformanceTableNarrativeTextBlock	Effective February 15, 2013, the Fund’s primary benchmark index changed from the S&P 500® Index to the Barclays Global Aggregate Bond Index to reflect the global investment strategies of the Fund. Additionally, the Fund changed the name of its secondary benchmark index from Conservative Allocation Index to Global Conservative Allocation Index and its composition from an internally-calculated, hypothetical combination of unmanaged indices that combines total returns from the Barclays U.S. Aggregate Bond Index (60%), the Dow Jones Wilshire 5000 Index (28%), and the Morgan Stanley Capital International Europe, Australasia, Far East Index (“MSCI EAFE®”) Index (12%) to an internally-calculated, hypothetical combination of unmanaged indices that combines total returns from the Barclays Global Aggregate Bond Index (60%) and the Morgan Stanley Capital International All Country World IndexSM (40%). The Barclays Global Aggregate Bond Index is an index that provides a broad-based measure of the global investment grade fixed-rate debt markets. Janus Capital believes that the foregoing benchmark index changes provide a more appropriate representation of the Fund’s revised investment strategy that includes an increased focus on global investments, including emerging markets. After-tax returns are calculated using distributions for the Fund’s Class D Shares for the periods following February 16, 2010; and for the Fund’s Class J Shares, the predecessor share class, for the periods prior to February 16, 2010. If Class D Shares of the Fund had been available during these earlier periods, distributions may have been different and thus, after-tax returns may have been different from those shown. After-tax returns are calculated using the historically highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes. Actual after-tax returns depend on your individual tax situation and may differ from those shown in the preceding table. The after-tax return information shown above does not apply to Fund shares held through a tax-deferred account, such as a 401(k) plan or an IRA.
Performance Table Closing [Text Block]	rr_PerformanceTableClosingTextBlock	Updated performance information is available at janus.com/allfunds or by calling 1-800-525-3713.
Janus Global Allocation Fund - Conservative | Class D Shares | Class D
Risk/Return:	rr_RiskReturnAbstract
Operating Expenses Column [Text]	rr_OperatingExpensesColumnName	Class D
Management Fees	rr_ManagementFeesOverAssets	0.05%
Other Expenses	rr_OtherExpensesOverAssets	0.20%
Acquired Fund Fees and Expenses	rr_AcquiredFundFeesAndExpensesOverAssets	0.60%
Total Annual Fund Operating Expenses	rr_ExpensesOverAssets	0.85%
Expense Example, By Year, Column [Text]	rr_ExpenseExampleByYearColumnName	Class D Shares
1 Year	rr_ExpenseExampleYear01	$ 87
3 Years	rr_ExpenseExampleYear03	271
5 Years	rr_ExpenseExampleYear05	471
10 Years	rr_ExpenseExampleYear10	$ 1,049
2006	rr_AnnualReturn2006	11.09%
2007	rr_AnnualReturn2007	10.19%
2008	rr_AnnualReturn2008	(16.01%)
2009	rr_AnnualReturn2009	23.37%
2010	rr_AnnualReturn2010	10.69%
2011	rr_AnnualReturn2011	1.51%
2012	rr_AnnualReturn2012	10.89%
Bar Chart, Year to Date Return, Date	rr_BarChartYearToDateReturnDate	Sep. 30, 2013
Bar Chart, Year to Date Return	rr_BarChartYearToDateReturn	6.60%
Highest Quarterly Return, Label	rr_HighestQuarterlyReturnLabel	Best Quarter:
Highest Quarterly Return, Date	rr_BarChartHighestQuarterlyReturnDate	Jun. 30, 2009
Highest Quarterly Return	rr_BarChartHighestQuarterlyReturn	10.64%
Lowest Quarterly Return, Label	rr_LowestQuarterlyReturnLabel	Worst Quarter:
Lowest Quarterly Return, Date	rr_BarChartLowestQuarterlyReturnDate	Sep. 30, 2008
Lowest Quarterly Return	rr_BarChartLowestQuarterlyReturn	(6.58%)
Janus Global Allocation Fund - Conservative | Class D Shares | Return Before Taxes | Class D
Risk/Return:	rr_RiskReturnAbstract
Column	rr_AverageAnnualReturnColumnName	Class D Shares
Label	rr_AverageAnnualReturnLabel	Return Before Taxes
1 Year	rr_AverageAnnualReturnYear01	10.89%
5 Years	rr_AverageAnnualReturnYear05	5.24%
Since Inception	rr_AverageAnnualReturnSinceInception	6.75%
Inception Date	rr_AverageAnnualReturnInceptionDate	Dec. 30, 2005
Janus Global Allocation Fund - Conservative | Class D Shares | Return After Taxes on Distributions | Class D
Risk/Return:	rr_RiskReturnAbstract
Column	rr_AverageAnnualReturnColumnName	Class D Shares
Label	rr_AverageAnnualReturnLabel	Return After Taxes on Distributions
1 Year	rr_AverageAnnualReturnYear01	9.95%
5 Years	rr_AverageAnnualReturnYear05	4.18%
Since Inception	rr_AverageAnnualReturnSinceInception	5.72%
Inception Date	rr_AverageAnnualReturnInceptionDate	Dec. 30, 2005
Janus Global Allocation Fund - Conservative | Class D Shares | Return After Taxes on Distributions and Sale of Fund Shares | Class D
Risk/Return:	rr_RiskReturnAbstract
Column	rr_AverageAnnualReturnColumnName	Class D Shares
Label	rr_AverageAnnualReturnLabel	Return After Taxes on Distributions and Sale of Fund Shares
1 Year	rr_AverageAnnualReturnYear01	7.22%
5 Years	rr_AverageAnnualReturnYear05	3.88%
Since Inception	rr_AverageAnnualReturnSinceInception	5.26%
Inception Date	rr_AverageAnnualReturnInceptionDate	Dec. 30, 2005
Janus Global Allocation Fund - Conservative | Class D Shares | Barclays Global Aggregate Bond Index (reflects no deduction for expenses, fees, or taxes)
Risk/Return:	rr_RiskReturnAbstract
Label	rr_AverageAnnualReturnLabel	Barclays Global Aggregate Bond Index
1 Year	rr_AverageAnnualReturnYear01	4.32%
5 Years	rr_AverageAnnualReturnYear05	5.44%
Since Inception	rr_AverageAnnualReturnSinceInception	6.18%
Inception Date	rr_AverageAnnualReturnInceptionDate	Dec. 30, 2005
Janus Global Allocation Fund - Conservative | Class D Shares | Global Conservative Allocation Index (reflects no deduction for expenses, fees, or taxes, except any applicable foreign withholding taxes)
Risk/Return:	rr_RiskReturnAbstract
Label	rr_AverageAnnualReturnLabel	Global Conservative Allocation Index
1 Year	rr_AverageAnnualReturnYear01	9.09%
5 Years	rr_AverageAnnualReturnYear05	3.22%
Since Inception	rr_AverageAnnualReturnSinceInception	5.48%
Inception Date	rr_AverageAnnualReturnInceptionDate	Dec. 30, 2005
Janus Global Allocation Fund - Conservative | Class D Shares | S&P 500® Index (reflects no deduction for expenses, fees, or taxes)
Risk/Return:	rr_RiskReturnAbstract
Label	rr_AverageAnnualReturnLabel	S&P 500® Index
1 Year	rr_AverageAnnualReturnYear01	16.00%
5 Years	rr_AverageAnnualReturnYear05	1.66%
Since Inception	rr_AverageAnnualReturnSinceInception	4.12%
Inception Date	rr_AverageAnnualReturnInceptionDate	Dec. 30, 2005
Janus Global Allocation Fund - Conservative | Class D Shares | Conservative Allocation Index (reflects no deduction for expenses, fees, or taxes, except any applicable foreign withholding taxes)
Risk/Return:	rr_RiskReturnAbstract
Label	rr_AverageAnnualReturnLabel	Conservative Allocation Index
1 Year	rr_AverageAnnualReturnYear01	9.21%
5 Years	rr_AverageAnnualReturnYear05	4.26%
Since Inception	rr_AverageAnnualReturnSinceInception	5.49%
Inception Date	rr_AverageAnnualReturnInceptionDate	Dec. 30, 2005

XML

Label	Element	Value
Risk/Return:	rr_RiskReturnAbstract
Registrant Name	dei_EntityRegistrantName	JANUS INVESTMENT FUND
Prospectus Date	rr_ProspectusDate	Oct. 28, 2013
Janus Short-Term Bond Fund | Class D Shares
Risk/Return:	rr_RiskReturnAbstract
Risk/Return [Heading]	rr_RiskReturnHeading	FUND SUMMARY Janus Short-Term Bond Fund
Objective [Heading]	rr_ObjectiveHeading	INVESTMENT OBJECTIVE
Objective, Primary [Text Block]	rr_ObjectivePrimaryTextBlock	Janus Short-Term Bond Fund seeks as high a level of current income as is consistent with preservation of capital.
Expense [Heading]	rr_ExpenseHeading	FEES AND EXPENSES OF THE FUND
Expense Narrative [Text Block]	rr_ExpenseNarrativeTextBlock	This table describes the fees and expenses that you may pay if you buy and hold Shares of the Fund.
Operating Expenses Caption [Text]	rr_OperatingExpensesCaption	ANNUAL FUND OPERATING EXPENSES (expenses that you pay each year as a percentage of the value of your investment)
Fee Waiver or Reimbursement over Assets, Date of Termination	rr_FeeWaiverOrReimbursementOverAssetsDateOfTermination	November 1, 2014
Portfolio Turnover [Heading]	rr_PortfolioTurnoverHeading	Portfolio Turnover:
Portfolio Turnover [Text Block]	rr_PortfolioTurnoverTextBlock	The Fund pays transaction costs, such as commissions, when it buys and sells securities (or “turns over” its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when Fund shares are held in a taxable account. These costs, which are not reflected in annual fund operating expenses or in the Example, affect the Fund’s performance. During the most recent fiscal year, the Fund’s portfolio turnover rate was 100% of the average value of its portfolio.
Portfolio Turnover, Rate	rr_PortfolioTurnoverRate	100.00%
Expense Example [Heading]	rr_ExpenseExampleHeading	EXAMPLE:
Expense Example by Year [Heading]	rr_ExpenseExampleByYearHeading	The Example assumes that you invest $10,000 in the Fund for the time periods indicated, reinvest all dividends and distributions, and then redeem all of your Shares at the end of each period. The Example also assumes that your investment has a 5% return each year and that the Fund’s operating expenses without waivers remain the same. Although your actual costs may be higher or lower, based on these assumptions your costs would be:
Expense Example Narrative [Text Block]	rr_ExpenseExampleNarrativeTextBlock	The following Example is based on expenses without waivers. The Example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds.
Strategy [Heading]	rr_StrategyHeading	PRINCIPAL INVESTMENT STRATEGIES
Strategy Narrative [Text Block]	rr_StrategyNarrativeTextBlock	The Fund invests, under normal circumstances, at least 80% of its net assets in short- and intermediate-term securities such as corporate bonds or notes or government securities, including agency securities. The Fund may invest up to 35% of its net assets in high-yield/high-risk bonds, also known as “junk” bonds. The Fund expects to maintain an average-weighted effective maturity of three years or less under normal circumstances. As of June 30, 2013, the Fund’s weighted average maturity was 2.5 years. The Fund may also invest in bank loans, mortgage-backed securities, asset-backed securities, and foreign debt securities (which may include investments in emerging markets). Due to the nature of securities in which the Fund invests, it may have relatively high portfolio turnover compared to other funds. “Effective” maturity differs from actual maturity, which may be longer. In calculating the “effective” maturity the portfolio managers will estimate the effect of expected principal payments and call provisions on securities held in the portfolio. This gives the portfolio managers some additional flexibility in the securities they purchase, but all else being equal, could result in more volatility than if the Fund calculated an actual maturity target. In addition, the Fund may invest its assets in derivatives, which are instruments that have a value derived from, or directly linked to, an underlying asset, such as equity securities, fixed-income securities, commodities, currencies, interest rates, or market indices. In particular, the Fund may use derivatives to manage portfolio risk or to manage the effective maturity of the securities in the Fund’s portfolio. The Fund’s exposure to derivatives will vary. For purposes of meeting its 80% investment policy, the Fund may include derivatives that have characteristics similar to the securities in which the Fund may directly invest. In addition to considering economic factors such as the effect of interest rates on the Fund’s investments, the portfolio managers apply a “bottom up” approach in choosing investments. This means that the portfolio managers look at income-producing securities one at a time to determine if a security is an attractive investment opportunity and if it is consistent with the Fund’s investment policies. The Fund may lend portfolio securities on a short-term or long-term basis, in an amount equal to up to 1/3 of its total assets as determined at the time of the loan origination.
Risk [Heading]	rr_RiskHeading	PRINCIPAL INVESTMENT RISKS
Risk Narrative [Text Block]	rr_RiskNarrativeTextBlock	Although the Fund may be less volatile than funds that invest most of their assets in common stocks, the Fund’s returns and yields will vary, and you could lose money. Fixed-Income Securities Risk. The Fund invests in a variety of fixed-income securities. Typically, the values of fixed-income securities change inversely with prevailing interest rates. Therefore, a fundamental risk of fixed-income securities is interest rate risk, which is the risk that the value of such securities will generally decline as prevailing interest rates rise, which may cause the Fund’s net asset value to likewise decrease. How specific fixed-income securities may react to changes in interest rates will depend on the specific characteristics of each security. Fixed-income securities are also subject to credit risk, prepayment risk, valuation risk, and liquidity risk. Credit risk is the risk that the credit strength of an issuer of a fixed-income security will weaken and/or that the issuer will be unable to make timely principal and interest payments and that the security may go into default. Prepayment risk is the risk that during periods of falling interest rates, certain fixed-income securities with higher interest rates, such as mortgage- and asset-backed securities, may be prepaid by their issuers thereby reducing the amount of interest payments. Valuation risk is the risk that one or more of the fixed-income securities in which the Fund invests are priced differently than the value realized upon such security’s sale. In times of market instability, valuation may be more difficult. Liquidity risk is the risk that fixed-income securities may be difficult or impossible to sell at the time that the portfolio managers would like or at the price the portfolio managers believe the security is currently worth. Sovereign Debt Risk. The Fund may invest in U.S. and foreign government debt securities (“sovereign debt”). Investments in U.S. sovereign debt are considered low risk. However, investments in non-U.S. sovereign debt can involve a high degree of risk, including the risk that the governmental entity that controls the repayment of sovereign debt may not be willing or able to repay the principal and/or to pay the interest on its sovereign debt in a timely manner. A sovereign debtor’s willingness or ability to satisfy its debt obligation may be affected by various factors including, but not limited to, its cash flow situation, the extent of its foreign currency reserves, the availability of foreign exchange when a payment is due, and the relative size of its debt position in relation to its economy as a whole. In the event of default, there may be limited or no legal remedies for collecting sovereign debt and there may be no bankruptcy proceedings through which the Fund may collect all or part of the sovereign debt that a governmental entity has not repaid. Foreign Exposure Risk. The Fund may have exposure to foreign markets as a result of its investments in foreign securities, including investments in emerging markets, which can be more volatile than the U.S. markets. As a result, its returns and net asset value may be affected to a large degree by fluctuations in currency exchange rates or political or economic conditions in a particular country. In some foreign markets, there may not be protection against failure by other parties to complete transactions. It may not be possible for the Fund to repatriate capital, dividends, interest, and other income from a particular country or governmental entity. In addition, a market swing in one or more countries or regions where the Fund has invested a significant amount of its assets may have a greater effect on the Fund’s performance than it would in a more geographically diversified portfolio. To the extent the Fund invests in foreign debt securities, such investments are sensitive to changes in interest rates. Additionally, investments in securities of foreign governments involve the risk that a foreign government may not be willing or able to pay interest or repay principal when due. The Fund’s investments in emerging market countries may involve risks greater than, or in addition to, the risks of investing in more developed countries. Eurozone Risk. A number of countries in the European Union (“EU”) have experienced severe economic and financial difficulties. As a result, financial markets in the EU have been subject to extreme volatility and declines in asset values and liquidity. Responses to these financial problems by European governments, central banks, and others, including austerity measures and reforms, may not work, may result in social unrest, and may limit future growth and economic recovery or have other unintended consequences. Further defaults or restructurings by governments and others of their debt could have additional adverse effects on economies, financial markets, and asset valuations around the world. To the extent that the Fund has exposure to European markets or to transactions tied to the value of the euro, these events could negatively affect the value and liquidity of the Fund’s investments. Mortgage-Backed Securities Risk. Mortgage-backed securities are classified generally as either commercial mortgage-backed securities or residential mortgage-backed securities, each of which is subject to certain specific risks. Mortgage-backed securities tend to be more sensitive to changes in interest rates than other types of debt securities. Investments in mortgage-backed securities are subject to both extension risk, where borrowers extend the duration of their mortgages in times of rising interest rates, and prepayment risk, where borrowers pay off their mortgages sooner than expected in times of declining interest rates. These risks may reduce the Fund’s returns. In addition, investments in mortgage-backed securities, including those comprised of subprime mortgages, may be subject to a higher degree of credit risk, valuation risk, and liquidity risk than various other types of fixed-income securities. Bank Loan Risk. Bank loans are obligations of companies or other entities entered into in connection with recapitalizations, acquisitions, and refinancings. The Fund’s investments in bank loans are generally acquired as a participation interest in, or assignment of, loans originated by a lender or other financial institution. These investments may include institutionally-traded floating and fixed-rate debt securities. Participation interests and assignments involve credit, interest rate, and liquidity risk. In addition, the bank loans underlying these securities often involve borrowers with low credit ratings whose financial conditions are troubled or uncertain, including companies that are highly leveraged or in bankruptcy proceedings. High-Yield/High-Risk Bond Risk. High-yield/high-risk bonds may be more sensitive than other types of bonds to economic changes, political changes, or adverse developments specific to the company that issued the bond, which may adversely affect their value. Portfolio Turnover Risk. Increased portfolio turnover may result in higher costs, which may have a negative effect on the Fund’s performance. In addition, higher portfolio turnover may result in the acceleration of capital gains and the recognition of greater levels of short-term capital gains, which are taxed at ordinary federal income tax rates when distributed to shareholders. Derivatives Risk. Derivatives can be highly volatile and involve risks in addition to the risks of the underlying referenced securities. Gains or losses from a derivative investment can be substantially greater than the derivative’s original cost, and can therefore involve leverage. Leverage may cause the Fund to be more volatile than if it had not used leverage. Derivatives can be less liquid than other types of investments and entail the risk that the counterparty will default on its payment obligations. Securities Lending Risk. The Fund may seek to earn additional income through lending its securities to certain qualified broker-dealers and institutions. There is the risk that when portfolio securities are lent, the securities may not be returned on a timely basis, and the Fund may experience delays and costs in recovering the security or gaining access to the collateral provided to the Fund to collateralize the loan. If the Fund is unable to recover a security on loan, the Fund may use the collateral to purchase replacement securities in the market. There is a risk that the value of the collateral could decrease below the cost of the replacement security by the time the replacement investment is made, resulting in a loss to the Fund. An investment in the Fund is not a bank deposit and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency.
Risk Lose Money [Text]	rr_RiskLoseMoney	Although the Fund may be less volatile than funds that invest most of their assets in common stocks, the Fund’s returns and yields will vary, and you could lose money.
Risk Not Insured Depository Institution [Text]	rr_RiskNotInsuredDepositoryInstitution	An investment in the Fund is not a bank deposit and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency.
Bar Chart and Performance Table [Heading]	rr_BarChartAndPerformanceTableHeading	PERFORMANCE INFORMATION
Performance Narrative [Text Block]	rr_PerformanceNarrativeTextBlock	The following information provides some indication of the risks of investing in the Fund by showing how the Fund’s performance has varied over time. Class D Shares of the Fund commenced operations on February 16, 2010, as a result of the restructuring of Class J Shares, the predecessor share class. The performance shown for Class D Shares for periods prior to February 16, 2010, reflects the performance of the Fund’s former Class J Shares, calculated using the fees and expenses in effect during the periods shown, net of any applicable fee and expense limitations or waivers. If Class D Shares of the Fund had been available during periods prior to February 16, 2010, the performance shown may have been different. The performance shown for periods following the Fund’s commencement of Class D Shares reflects the fees and expenses of Class D Shares, net of any applicable fee and expense limitations or waivers. The bar chart depicts the change in performance from year to year during the periods indicated. The table compares the Fund’s average annual returns for the periods indicated to a broad-based securities market index. The index is not actively managed and is not available for direct investment. All figures assume reinvestment of dividends and distributions. For certain periods, the Fund’s performance reflects the effect of expense waivers. Without the effect of these expense waivers, the performance shown would have been lower. The Fund’s past performance (before and after taxes) does not necessarily indicate how it will perform in the future. Updated performance information is available at janus.com/allfunds or by calling 1-800-525-3713.
Performance Information Illustrates Variability of Returns [Text]	rr_PerformanceInformationIllustratesVariabilityOfReturns	The following information provides some indication of the risks of investing in the Fund by showing how the Fund’s performance has varied over time. The bar chart depicts the change in performance from year to year during the periods indicated.
Performance Additional Market Index [Text]	rr_PerformanceAdditionalMarketIndex	The table compares the Fund’s average annual returns for the periods indicated to a broad-based securities market index. The index is not actively managed and is not available for direct investment. All figures assume reinvestment of dividends and distributions.
Performance Availability Phone [Text]	rr_PerformanceAvailabilityPhone	1-800-525-3713
Performance Availability Website Address [Text]	rr_PerformanceAvailabilityWebSiteAddress	janus.com/allfunds
Performance Past Does Not Indicate Future [Text]	rr_PerformancePastDoesNotIndicateFuture	The Fund’s past performance (before and after taxes) does not necessarily indicate how it will perform in the future.
Bar Chart [Heading]	rr_BarChartHeading	Annual Total Returns for Class D Shares (calendar year-end)
Bar Chart Closing [Text Block]	rr_BarChartClosingTextBlock	Best Quarter:  Second Quarter 2009  3.18%          Worst Quarter:  Second Quarter 2008  −0.90%
Year to Date Return, Label	rr_YearToDateReturnLabel	The Fund’s year-to-date return as of the calendar quarter ended September 30, 2013 was 0.79%.
Performance Table Heading	rr_PerformanceTableHeading	Average Annual Total Returns (periods ended 12/31/12)
Performance Table Uses Highest Federal Rate	rr_PerformanceTableUsesHighestFederalRate	After-tax returns are calculated using the historically highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes.
Performance Table Not Relevant to Tax Deferred	rr_PerformanceTableNotRelevantToTaxDeferred	Actual after-tax returns depend on your individual tax situation and may differ from those shown in the preceding table. The after-tax return information shown above does not apply to Fund shares held through a tax-deferred account, such as a 401(k) plan or an IRA.
Performance Table Narrative	rr_PerformanceTableNarrativeTextBlock	After-tax returns are calculated using distributions for the Fund’s Class D Shares for the periods following February 16, 2010; and for the Fund’s Class J Shares, the predecessor share class, for the periods prior to February 16, 2010. If Class D Shares of the Fund had been available during these earlier periods, distributions may have been different and thus, after-tax returns may have been different from those shown. After-tax returns are calculated using the historically highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes. Actual after-tax returns depend on your individual tax situation and may differ from those shown in the preceding table. The after-tax return information shown above does not apply to Fund shares held through a tax-deferred account, such as a 401(k) plan or an IRA.
Performance Table Closing [Text Block]	rr_PerformanceTableClosingTextBlock	Updated performance information is available at janus.com/allfunds or by calling 1-800-525-3713.
Janus Short-Term Bond Fund | Class D Shares | Class D
Risk/Return:	rr_RiskReturnAbstract
Operating Expenses Column [Text]	rr_OperatingExpensesColumnName	Class D
Management Fees	rr_ManagementFeesOverAssets	0.55%
Other Expenses	rr_OtherExpensesOverAssets	0.22%
Total Annual Fund Operating Expenses	rr_ExpensesOverAssets	0.77%	[1]
Fee Waiver	rr_FeeWaiverOrReimbursementOverAssets	0.15%	[1]
Total Annual Fund Operating Expenses After Fee Waiver	rr_NetExpensesOverAssets	0.62%	[1]
Expense Example, By Year, Column [Text]	rr_ExpenseExampleByYearColumnName	Class D Shares
1 Year	rr_ExpenseExampleYear01	$ 79
3 Years	rr_ExpenseExampleYear03	246
5 Years	rr_ExpenseExampleYear05	428
10 Years	rr_ExpenseExampleYear10	$ 954
2003	rr_AnnualReturn2003	3.91%
2004	rr_AnnualReturn2004	1.96%
2005	rr_AnnualReturn2005	1.52%
2006	rr_AnnualReturn2006	4.21%
2007	rr_AnnualReturn2007	5.21%
2008	rr_AnnualReturn2008	4.63%
2009	rr_AnnualReturn2009	8.56%
2010	rr_AnnualReturn2010	3.48%
2011	rr_AnnualReturn2011	1.50%
2012	rr_AnnualReturn2012	3.53%
Bar Chart, Year to Date Return, Date	rr_BarChartYearToDateReturnDate	Sep. 30, 2013
Bar Chart, Year to Date Return	rr_BarChartYearToDateReturn	0.79%
Highest Quarterly Return, Label	rr_HighestQuarterlyReturnLabel	Best Quarter:
Highest Quarterly Return, Date	rr_BarChartHighestQuarterlyReturnDate	Jun. 30, 2009
Highest Quarterly Return	rr_BarChartHighestQuarterlyReturn	3.18%
Lowest Quarterly Return, Label	rr_LowestQuarterlyReturnLabel	Worst Quarter:
Lowest Quarterly Return, Date	rr_BarChartLowestQuarterlyReturnDate	Jun. 30, 2008
Lowest Quarterly Return	rr_BarChartLowestQuarterlyReturn	(0.90%)
Janus Short-Term Bond Fund | Class D Shares | Return Before Taxes | Class D
Risk/Return:	rr_RiskReturnAbstract
Column	rr_AverageAnnualReturnColumnName	Class D Shares
Label	rr_AverageAnnualReturnLabel	Return Before Taxes
1 Year	rr_AverageAnnualReturnYear01	3.53%
5 Years	rr_AverageAnnualReturnYear05	4.31%
10 Years	rr_AverageAnnualReturnYear10	3.83%
Since Inception	rr_AverageAnnualReturnSinceInception	4.60%
Inception Date	rr_AverageAnnualReturnInceptionDate	Sep. 01, 1992
Janus Short-Term Bond Fund | Class D Shares | Return After Taxes on Distributions | Class D
Risk/Return:	rr_RiskReturnAbstract
Column	rr_AverageAnnualReturnColumnName	Class D Shares
Label	rr_AverageAnnualReturnLabel	Return After Taxes on Distributions
1 Year	rr_AverageAnnualReturnYear01	2.72%
5 Years	rr_AverageAnnualReturnYear05	3.28%
10 Years	rr_AverageAnnualReturnYear10	2.69%
Since Inception	rr_AverageAnnualReturnSinceInception	2.92%
Inception Date	rr_AverageAnnualReturnInceptionDate	Sep. 01, 1992
Janus Short-Term Bond Fund | Class D Shares | Return After Taxes on Distributions and Sale of Fund Shares | Class D
Risk/Return:	rr_RiskReturnAbstract
Column	rr_AverageAnnualReturnColumnName	Class D Shares
Label	rr_AverageAnnualReturnLabel	Return After Taxes on Distributions and Sale of Fund Shares
1 Year	rr_AverageAnnualReturnYear01	2.38%
5 Years	rr_AverageAnnualReturnYear05	3.10%
10 Years	rr_AverageAnnualReturnYear10	2.62%
Since Inception	rr_AverageAnnualReturnSinceInception	2.89%
Inception Date	rr_AverageAnnualReturnInceptionDate	Sep. 01, 1992
Janus Short-Term Bond Fund | Class D Shares | Barclays 1-3 Year U.S. Government/Credit Index (reflects no deduction for expenses, fees, or taxes)
Risk/Return:	rr_RiskReturnAbstract
Label	rr_AverageAnnualReturnLabel	Barclays 1-3 Year U.S. Government/Credit Index
1 Year	rr_AverageAnnualReturnYear01	1.26%
5 Years	rr_AverageAnnualReturnYear05	2.88%
10 Years	rr_AverageAnnualReturnYear10	3.13%
Since Inception	rr_AverageAnnualReturnSinceInception	4.62%
Inception Date	rr_AverageAnnualReturnInceptionDate	Sep. 01, 1992

[1] Janus Capital has contractually agreed to waive its investment advisory fee and/or reimburse Fund expenses to the extent that the Fund’s total annual fund operating expenses (excluding administrative services fees payable pursuant to the Transfer Agency Agreement, brokerage commissions, interest, dividends, taxes, acquired fund fees and expenses, and extraordinary expenses) exceed 0.49% until at least November 1, 2014. The contractual waiver may be terminated or modified prior to this date only at the discretion of the Board of Trustees.

XML

Label	Element	Value
Risk/Return:	rr_RiskReturnAbstract
Registrant Name	dei_EntityRegistrantName	JANUS INVESTMENT FUND
Prospectus Date	rr_ProspectusDate	Oct. 28, 2013
Janus Global Allocation Fund - Growth | Class D Shares
Risk/Return:	rr_RiskReturnAbstract
Risk/Return [Heading]	rr_RiskReturnHeading	FUND SUMMARY Janus Global Allocation Fund – Growth (formerly named Janus Growth Allocation Fund)
Objective [Heading]	rr_ObjectiveHeading	INVESTMENT OBJECTIVE
Objective, Primary [Text Block]	rr_ObjectivePrimaryTextBlock	Janus Global Allocation Fund – Growth seeks total return through a primary emphasis on growth of capital with a secondary emphasis on income.
Expense [Heading]	rr_ExpenseHeading	FEES AND EXPENSES OF THE FUND
Expense Narrative [Text Block]	rr_ExpenseNarrativeTextBlock	This table describes the fees and expenses that you may pay if you buy and hold Shares of the Fund.
Operating Expenses Caption [Text]	rr_OperatingExpensesCaption	ANNUAL FUND OPERATING EXPENSES (expenses that you pay each year as a percentage of the value of your investment)
Portfolio Turnover [Heading]	rr_PortfolioTurnoverHeading	Portfolio Turnover:
Portfolio Turnover [Text Block]	rr_PortfolioTurnoverTextBlock	The Fund pays transaction costs, such as commissions, when it buys and sells securities (or “turns over” its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when Fund shares are held in a taxable account. These costs, which are not reflected in annual fund operating expenses or in the Example, affect the Fund’s performance. During the most recent fiscal year, the Fund’s portfolio turnover rate was 45% of the average value of its portfolio.
Portfolio Turnover, Rate	rr_PortfolioTurnoverRate	45.00%
Expense Example [Heading]	rr_ExpenseExampleHeading	EXAMPLE:
Expense Example by Year [Heading]	rr_ExpenseExampleByYearHeading	The Example assumes that you invest $10,000 in the Fund for the time periods indicated, reinvest all dividends and distributions, and then redeem all of your Shares at the end of each period. The Example also assumes that your investment has a 5% return each year and that the Fund’s operating expenses (including the operating expenses of the underlying funds) remain the same. Although your actual costs may be higher or lower, based on these assumptions your costs would be:
Expense Example Narrative [Text Block]	rr_ExpenseExampleNarrativeTextBlock	The Example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds.
Strategy [Heading]	rr_StrategyHeading	PRINCIPAL INVESTMENT STRATEGIES
Strategy Narrative [Text Block]	rr_StrategyNarrativeTextBlock	The Fund seeks to achieve its investment objective by investing in other Janus mutual funds (“underlying funds”) that represent a variety of asset classes and investment styles and provide exposure to issuers that are economically tied to countries throughout the world. Through its investments in underlying funds, the Fund invests in issuers from several different countries and may, under unusual circumstances, be invested in a single country. As a result, the Fund normally will have approximately 40% of its net assets allocated to non-U.S. investments. The Fund may also have significant exposure to emerging markets. The Fund pursues this objective by investing in a diversified portfolio of underlying funds, resulting in an allocation of the Fund’s investments that normally provides exposure of approximately 75% to equity investments, 15% to fixed-income securities and money market instruments, and 10% to alternative investments. The target allocation and the allocation of the Fund’s assets among underlying funds are based on quantitative and qualitative analysis. Because it invests in other funds, the Fund is considered a “fund of funds.” The Fund’s asset allocation is intended to diversify investments throughout the world among equity investments, fixed-income securities, cash equivalents, and alternative investments. The portfolio manager determines the overall composition of the Fund, oversees the investment process, and is responsible for the day-to-day management of the Fund. The portfolio manager continually monitors asset class allocations and periodically rebalances the Fund’s investments in the underlying funds. The portfolio manager also regularly reviews the allocation of Fund assets in the underlying funds and may modify the underlying funds’ weightings or substitute other underlying funds to emphasize and mitigate risk exposures that may arise as a result of the implementation of the allocations. An independent asset allocation service provides evaluations of asset allocations that the portfolio manager may use in implementing the allocations among the underlying funds. Additionally, the portfolio manager consults with a committee (the “Janus Global Allocation Committee”) to regularly review the broad market, macroeconomic conditions and other global financial factors that may impact the Fund’s allocation of assets among the underlying funds and asset classes. The Janus Global Allocation Committee is comprised of investment professionals of Janus Capital and may also include investment professionals of Janus Capital’s affiliated investment advisers. The portfolio manager and Janus Global Allocation Committee normally meet on a quarterly basis. The portfolio manager may change the Fund’s asset class allocations, the underlying funds, an underlying fund’s asset category, or weightings among asset classes or underlying funds without prior shareholder notice. The Fund will normally allocate approximately 75% of its investments to underlying funds that provide varying exposure to common stocks of large U.S.-based companies, small- to mid-capitalization companies, and international companies (including those with exposure to emerging markets), approximately 15% of its investments to underlying bond funds and money market instruments, and approximately 10% of its investments to underlying funds that seek returns uncorrelated with the returns of stocks and bonds by providing exposure to alternative investments and alternative investment strategies. Refer to Appendix A in this Prospectus for a brief description of the investment strategies of each of the currently available underlying funds. When market conditions dictate a more defensive strategy, the Fund or an underlying fund may temporarily hold cash or invest its assets in temporary investments. In that case, the Fund may take positions that are inconsistent with its investment objective. As a result, the Fund may not achieve its investment objective.
Risk [Heading]	rr_RiskHeading	PRINCIPAL INVESTMENT RISKS
Risk Narrative [Text Block]	rr_RiskNarrativeTextBlock	The biggest risk is that the Fund’s returns will vary, and you could lose money. The Fund is designed for long-term investors seeking growth of capital and, to a lesser extent, income. Investments in a portfolio with common stock and alternative investment exposure tend to be more volatile than many other investment choices. Main Risks Associated with the Fund Allocation Risk. The Fund’s ability to achieve its investment objective depends largely upon the portfolio manager’s allocation of assets among the underlying funds and other securities, using the optimization process (a process that utilizes quantitative analysis of a number of factors, such as historical risk, performance, fund classifications, and the relationship among underlying funds) and the judgment of the portfolio manager. You could lose money on your investment in the Fund as a result of these allocations. The Fund will typically invest in a number of different underlying funds; however, to the extent that the Fund invests a significant portion of its assets in a single underlying fund, it will be more sensitive to the risks associated with that fund and any investments in which that fund focuses. Affiliated Fund Risk. Janus Capital has the authority to select and substitute underlying affiliated mutual funds. The fees paid to Janus Capital by some Janus mutual funds are generally higher than the fees paid to Janus Capital by the Fund or by other funds and share classes available for investment by the Fund. These conditions may create a conflict of interest when selecting underlying affiliated mutual funds and share classes for investment. Janus Capital, however, is a fiduciary to the Fund and its shareholders and is legally obligated to act in their best interest when selecting underlying affiliated mutual funds. Main Risks Associated with the Underlying Funds and Securities The biggest risk is that the underlying funds’ returns will vary, and you could lose money. Market Risk. Approximately 75% of the Fund’s assets are allocated to equity investments through investments in underlying funds. The value of an underlying fund’s portfolio may decrease if the value of an individual company or security, or multiple companies or securities, in the portfolio decreases or if a portfolio manager’s belief about a company’s intrinsic worth is incorrect. Further, regardless of how well individual companies or securities perform, the value of an underlying fund’s portfolio could also decrease if there are deteriorating economic or market conditions. It is important to understand that the value of your investment may fall, sometimes sharply, in response to changes in the market, and you could lose money. Foreign Exposure Risk. Certain underlying funds may have significant exposure to foreign markets as a result of their investments in foreign securities, including investments in emerging markets, which can be more volatile than the U.S. markets. As a result, an underlying fund’s returns and net asset value may be affected to a large degree by fluctuations in currency exchange rates or political or economic conditions in a particular country. A market swing in one or more countries or regions where an underlying fund has invested a significant amount of its assets may have a greater effect on an underlying fund’s performance than it would in a more geographically diversified portfolio. An underlying fund’s investments in emerging market countries may involve risks greater than, or in addition to, the risks of investing in more developed countries. Emerging Markets Risk. The risks of foreign investing mentioned above are heightened when investing in emerging markets. Emerging markets securities involve a number of additional risks, which may result from less government supervision and regulation of business and industry practices (including the potential lack of strict finance and accounting controls and standards), stock exchanges, brokers, and listed companies, making these investments potentially more volatile in price and less liquid than investments in developed securities markets, resulting in greater risk to investors. In addition, an underlying fund’s investments may be denominated in foreign currencies and therefore, changes in the value of a country’s currency compared to the U.S. dollar may affect the value of an underlying fund’s investments. To the extent that an underlying fund invests a significant portion of its assets in the securities of issuers in or companies of a single country or region, it is more likely to be impacted by events or conditions affecting that country or region, which could have a negative impact on the Fund’s performance. Some of the risks of investing directly in foreign and emerging market securities may be reduced when an underlying fund invests indirectly in foreign securities through various other investment vehicles including derivatives, which also involve other risks. Sovereign Debt Risk. An underlying fund may invest in U.S. and foreign government debt securities (“sovereign debt”). Investments in U.S. sovereign debt are considered low risk. However, investments in non-U.S. sovereign debt can involve a high degree of risk, including the risk that the governmental entity that controls the repayment of sovereign debt may not be willing or able to repay the principal and/or to pay the interest on its sovereign debt in a timely manner. A sovereign debtor’s willingness or ability to satisfy its debt obligation may be affected by various factors including, but not limited to, its cash flow situation, the extent of its foreign currency reserves, the availability of foreign exchange when a payment is due, and the relative size of its debt position in relation to its economy as a whole. In the event of default, there may be limited or no legal remedies for collecting sovereign debt and there may be no bankruptcy proceedings through which the underlying fund may collect all or part of the sovereign debt that a governmental entity has not repaid. Fixed-Income Securities Risk. Approximately 15% of the Fund’s assets are allocated to fixed-income securities through investments in underlying funds. Typically, the values of fixed-income securities change inversely with prevailing interest rates. Therefore, a fundamental risk of fixed-income securities is interest rate risk, which is the risk that the value of such securities will generally decline as prevailing interest rates rise, which may cause an underlying fund’s net asset value to likewise decrease. How specific fixed-income securities may react to changes in interest rates will depend on the specific characteristics of each security. Fixed-income securities are also subject to credit risk, prepayment risk, valuation risk, and liquidity risk. Credit risk is the risk that the credit strength of an issuer of a fixed-income security will weaken and/or that the issuer will be unable to make timely principal and interest payments and that the security may go into default. Prepayment risk is the risk that during periods of falling interest rates, certain fixed-income securities with higher interest rates, such as mortgage- and asset-backed securities, may be prepaid by their issuers thereby reducing the amount of interest payments. Valuation risk is the risk that one or more of the fixed-income securities in which an underlying fund invests are priced differently than the value realized upon such security’s sale. In times of market instability, valuation may be more difficult. Liquidity risk is the risk that fixed-income securities may be difficult or impossible to sell at the time that an underlying fund’s portfolio manager would like or at the price the portfolio manager believes the security is currently worth. Mortgage-Backed Securities Risk. Mortgage-backed securities are classified generally as either commercial mortgage-backed securities or residential mortgage-backed securities, each of which is subject to certain specific risks. Mortgage-backed securities tend to be more sensitive to changes in interest rates than other types of debt securities. Investments in mortgage-backed securities are subject to both extension risk, where borrowers extend the duration of their mortgages in times of rising interest rates, and prepayment risk, where borrowers pay off their mortgages sooner than expected in times of declining interest rates. These risks may reduce the Fund’s returns. In addition, investments in mortgage-backed securities, including those comprised of subprime mortgages, may be subject to a higher degree of credit risk, valuation risk, and liquidity risk than various other types of fixed-income securities. Alternative Investments Allocation Risk. Approximately 10% of the Fund’s assets are allocated to alternative investments through investments in underlying funds that invest in alternative investment strategies. In connection with the Fund’s allocation to alternative investments, the Fund may invest in a Janus underlying fund, Janus Diversified Alternatives Fund, which seeks returns uncorrelated with the returns generated by investments in stocks and bonds. In addition, as part of its alternative investments allocation, the Fund may invest in Janus Global Real Estate Fund. Janus Diversified Alternatives Fund’s ability to achieve its investment objective depends largely upon the successful evaluation of the risk, potential returns, and correlation properties with respect to its investments. There is a risk that the returns provided by alternative investments may be subject to high volatility and that an underlying fund’s portfolio manager’s beliefs about the expected returns, risk and correlation properties of one or more of an underlying fund’s investments may be incorrect. There is also a risk that an underlying fund’s investments will correlate with the performance of stocks and bonds to a greater degree than anticipated. Janus Capital does not have prior experience managing the investment strategy of Janus Diversified Alternatives Fund, and there is no guarantee that the investment techniques and analysis used by the underlying fund’s portfolio managers will produce the desired results. All of these factors may negatively affect your investment in the Fund and you could lose money. Investment in the underlying funds also involves derivatives, counterparty, leverage, real estate-related, and commodity-linked investment risks. Counterparty Risk. Certain derivative and “over-the-counter” instruments, such as swaps and forwards, are subject to the risk that the other party to a contract will not fulfill its contractual obligations. Commodity-Linked Investments Risk. Certain underlying funds may invest in derivatives that have exposure to the commodities markets. Such exposure may subject an underlying fund to greater volatility than investments in traditional securities. The value of a commodity-linked derivative investment typically is based upon the price movements of a physical commodity (such as heating oil, livestock, or agricultural products), a commodity futures contract or commodity index, or some other readily measurable economic variable. The value of commodity-linked derivative instruments may therefore be affected by changes in overall market movements, volatility of the underlying benchmark, changes in interest rates, or other factors affecting a particular industry or commodity such as drought, floods, weather, livestock disease, embargoes, tariffs, and international economic, political, and regulatory developments. Derivatives Risk. Certain underlying funds may invest in derivatives. Derivatives can be highly volatile and involve risks in addition to the risks of the underlying referenced securities. Gains or losses from a derivative investment can be substantially greater than the derivative’s original cost, and can therefore involve leverage. Leverage may cause an underlying fund to be more volatile than if it had not used leverage. Derivatives can be less liquid than other types of investments and entail the risk that the counterparty will default on its payment obligations. Exchange-Traded Funds Risk. Certain underlying funds may purchase shares of exchange-traded funds (“ETFs”) to gain exposure to a particular portion of the market. ETFs are pooled investment vehicles, which may be managed or unmanaged, that generally seek to track the performance of a specific index. ETFs are traded on an exchange at market prices that may vary from the net asset value of their underlying investments. When an underlying fund invests in an ETF, in addition to directly bearing the expenses associated with its own operations, it will bear a pro rata portion of the ETF’s expenses. ETFs have certain inherent risks generally associated with investments in a portfolio of securities in which the ETF is invested, including the risk that the general level of stock prices may decline, thereby adversely affecting the value of each unit of the ETF. ETFs also involve the risk that an active trading market for an ETF’s shares may not develop or be maintained. Exchange-Traded Notes Risk. Certain underlying funds may invest in exchange-traded notes (“ETNs”), which are debt securities whose returns are linked to a particular index. ETNs are typically linked to the performance of a commodities index that reflects the potential return on unleveraged investments in futures contracts of physical commodities, plus a specified rate of interest that could be earned on cash collateral. ETNs are subject to credit risk and counterparty risk. The value of an ETN may vary and may be influenced by time to maturity, level of supply and demand for the ETN, volatility and lack of liquidity in underlying commodities markets, changes in the applicable interest rates, changes in the issuer’s credit rating, and economic, legal, political, or geographic events that affect the referenced commodity. When an underlying fund invests in ETNs it will bear its proportionate share of any fees and expenses borne by the ETN. There may be restrictions on an underlying fund’s right to redeem its investment in an ETN, which is meant to be held until maturity. An underlying fund’s decision to sell its ETN holdings may be limited by the availability of a secondary market. An investment in the Fund is not a bank deposit and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency.
Risk Lose Money [Text]	rr_RiskLoseMoney	The biggest risk is that the Fund's returns will vary, and you could lose money.
Risk Not Insured Depository Institution [Text]	rr_RiskNotInsuredDepositoryInstitution	An investment in the Fund is not a bank deposit and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency.
Bar Chart and Performance Table [Heading]	rr_BarChartAndPerformanceTableHeading	PERFORMANCE INFORMATION
Performance Narrative [Text Block]	rr_PerformanceNarrativeTextBlock	The following information provides some indication of the risks of investing in the Fund by showing how the Fund’s performance has varied over time. Class D Shares of the Fund commenced operations on February 16, 2010, as a result of the restructuring of Class J Shares, the predecessor share class. The performance shown for Class D Shares for periods prior to February 16, 2010, reflects the performance of the Fund’s former Class J Shares, calculated using the fees and expenses in effect during the periods shown, net of any applicable fee and expense limitations or waivers. If Class D Shares of the Fund had been available during periods prior to February 16, 2010, the performance shown may have been different. The performance shown for periods following the Fund’s commencement of Class D Shares reflects the fees and expenses of Class D Shares, net of any applicable fee and expense limitations or waivers. The bar chart depicts the change in performance from year to year during the periods indicated. Performance information for each underlying fund is available in its prospectus and/or the most recent annual or semiannual report. The table compares the Fund’s average annual returns for the periods indicated to broad-based securities market indices. The indices are not actively managed and are not available for direct investment. All figures assume reinvestment of dividends and distributions. For certain periods, the Fund’s performance reflects the effect of expense waivers. Without the effect of these expense waivers, the performance shown would have been lower. The Fund’s past performance (before and after taxes) does not necessarily indicate how it will perform in the future. Updated performance information is available at janus.com/allfunds or by calling 1-800-525-3713.
Performance Information Illustrates Variability of Returns [Text]	rr_PerformanceInformationIllustratesVariabilityOfReturns	The following information provides some indication of the risks of investing in the Fund by showing how the Fund’s performance has varied over time. The bar chart depicts the change in performance from year to year during the periods indicated.
Performance Additional Market Index [Text]	rr_PerformanceAdditionalMarketIndex	The table compares the Fund’s average annual returns for the periods indicated to broad-based securities market indices. The indices are not actively managed and are not available for direct investment. All figures assume reinvestment of dividends and distributions.
Performance Availability Phone [Text]	rr_PerformanceAvailabilityPhone	1-800-525-3713
Performance Availability Website Address [Text]	rr_PerformanceAvailabilityWebSiteAddress	janus.com/allfunds
Performance Past Does Not Indicate Future [Text]	rr_PerformancePastDoesNotIndicateFuture	The Fund’s past performance (before and after taxes) does not necessarily indicate how it will perform in the future.
Bar Chart [Heading]	rr_BarChartHeading	Annual Total Returns for Class D Shares (calendar year-end)
Bar Chart Closing [Text Block]	rr_BarChartClosingTextBlock	Best Quarter:  Second Quarter 2009  18.37%          Worst Quarter:  Fourth Quarter 2008  −18.05%
Year to Date Return, Label	rr_YearToDateReturnLabel	The Fund’s year-to-date return as of the calendar quarter ended September 30, 2013 was 12.38%.
Performance Table Heading	rr_PerformanceTableHeading	Average Annual Total Returns (periods ended 12/31/12)
Performance Table Uses Highest Federal Rate	rr_PerformanceTableUsesHighestFederalRate	After-tax returns are calculated using the historically highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes.
Performance Table Not Relevant to Tax Deferred	rr_PerformanceTableNotRelevantToTaxDeferred	Actual after-tax returns depend on your individual tax situation and may differ from those shown in the preceding table. The after-tax return information shown above does not apply to Fund shares held through a tax-deferred account, such as a 401(k) plan or an IRA.
Performance Table Explanation after Tax Higher	rr_PerformanceTableExplanationAfterTaxHigher	If the Fund incurs a loss, which generates a tax benefit, the Return After Taxes on Distributions and Sale of Fund Shares may exceed the Fund’s other return figures.
Performance Table Narrative	rr_PerformanceTableNarrativeTextBlock	Effective February 15, 2013, the Fund’s primary benchmark index changed from the S&P 500® Index to the Morgan Stanley Capital International (“MSCI”) All Country World IndexSM to reflect the global investment strategies of the Fund. Additionally, the Fund changed the name of its secondary benchmark index from Growth Allocation Index to Global Growth Allocation Index and its composition from an internally-calculated, hypothetical combination of unmanaged indices that combines total returns from the Dow Jones Wilshire 5000 Index (50%), the MSCI EAFE® Index (25%), the Barclays U.S. Aggregate Bond Index (20%), and the MSCI Emerging Markets Free IndexSM (5%) to an internally-calculated, hypothetical combination of unmanaged indices that combines total returns from the MSCI All Country World IndexSM (80%) and the Barclays Global Aggregate Bond Index (20%). The MSCI All Country World IndexSM is an unmanaged, free float-adjusted market capitalization weighted index that is designed to measure the equity market performance of global developed and emerging markets. Janus Capital believes that the foregoing benchmark index changes provide a more appropriate representation of the Fund’s revised investment strategy that includes an increased focus on global investments, including emerging markets. After-tax returns are calculated using distributions for the Fund’s Class D Shares for the periods following February 16, 2010; and for the Fund’s Class J Shares, the predecessor share class, for the periods prior to February 16, 2010. If Class D Shares of the Fund had been available during these earlier periods, distributions may have been different and thus, after-tax returns may have been different from those shown. After-tax returns are calculated using the historically highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes. Actual after-tax returns depend on your individual tax situation and may differ from those shown in the preceding table. The after-tax return information shown above does not apply to Fund shares held through a tax-deferred account, such as a 401(k) plan or an IRA.
Performance Table Closing [Text Block]	rr_PerformanceTableClosingTextBlock	Updated performance information is available at janus.com/allfunds or by calling 1-800-525-3713.
Janus Global Allocation Fund - Growth | Class D Shares | Class D
Risk/Return:	rr_RiskReturnAbstract
Operating Expenses Column [Text]	rr_OperatingExpensesColumnName	Class D
Management Fees	rr_ManagementFeesOverAssets	0.05%
Other Expenses	rr_OtherExpensesOverAssets	0.23%
Acquired Fund Fees and Expenses	rr_AcquiredFundFeesAndExpensesOverAssets	0.71%
Total Annual Fund Operating Expenses	rr_ExpensesOverAssets	0.99%
Expense Example, By Year, Column [Text]	rr_ExpenseExampleByYearColumnName	Class D Shares
1 Year	rr_ExpenseExampleYear01	$ 101
3 Years	rr_ExpenseExampleYear03	315
5 Years	rr_ExpenseExampleYear05	547
10 Years	rr_ExpenseExampleYear10	$ 1,213
2006	rr_AnnualReturn2006	18.51%
2007	rr_AnnualReturn2007	15.73%
2008	rr_AnnualReturn2008	(34.91%)
2009	rr_AnnualReturn2009	35.79%
2010	rr_AnnualReturn2010	13.53%
2011	rr_AnnualReturn2011	(6.44%)
2012	rr_AnnualReturn2012	14.93%
Bar Chart, Year to Date Return, Date	rr_BarChartYearToDateReturnDate	Sep. 30, 2013
Bar Chart, Year to Date Return	rr_BarChartYearToDateReturn	12.38%
Highest Quarterly Return, Label	rr_HighestQuarterlyReturnLabel	Best Quarter:
Highest Quarterly Return, Date	rr_BarChartHighestQuarterlyReturnDate	Jun. 30, 2009
Highest Quarterly Return	rr_BarChartHighestQuarterlyReturn	18.37%
Lowest Quarterly Return, Label	rr_LowestQuarterlyReturnLabel	Worst Quarter:
Lowest Quarterly Return, Date	rr_BarChartLowestQuarterlyReturnDate	Dec. 31, 2008
Lowest Quarterly Return	rr_BarChartLowestQuarterlyReturn	(18.05%)
Janus Global Allocation Fund - Growth | Class D Shares | Return Before Taxes | Class D
Risk/Return:	rr_RiskReturnAbstract
Column	rr_AverageAnnualReturnColumnName	Class D Shares
Label	rr_AverageAnnualReturnLabel	Return Before Taxes
1 Year	rr_AverageAnnualReturnYear01	14.93%
5 Years	rr_AverageAnnualReturnYear05	1.53%
Since Inception	rr_AverageAnnualReturnSinceInception	5.75%
Inception Date	rr_AverageAnnualReturnInceptionDate	Dec. 30, 2005
Janus Global Allocation Fund - Growth | Class D Shares | Return After Taxes on Distributions | Class D
Risk/Return:	rr_RiskReturnAbstract
Column	rr_AverageAnnualReturnColumnName	Class D Shares
Label	rr_AverageAnnualReturnLabel	Return After Taxes on Distributions
1 Year	rr_AverageAnnualReturnYear01	14.42%
5 Years	rr_AverageAnnualReturnYear05	1.03%
Since Inception	rr_AverageAnnualReturnSinceInception	5.15%
Inception Date	rr_AverageAnnualReturnInceptionDate	Dec. 30, 2005
Janus Global Allocation Fund - Growth | Class D Shares | Return After Taxes on Distributions and Sale of Fund Shares | Class D
Risk/Return:	rr_RiskReturnAbstract
Column	rr_AverageAnnualReturnColumnName	Class D Shares
Label	rr_AverageAnnualReturnLabel	Return After Taxes on Distributions and Sale of Fund Shares	[1]
1 Year	rr_AverageAnnualReturnYear01	10.00%
5 Years	rr_AverageAnnualReturnYear05	1.06%
Since Inception	rr_AverageAnnualReturnSinceInception	4.71%
Inception Date	rr_AverageAnnualReturnInceptionDate	Dec. 30, 2005
Janus Global Allocation Fund - Growth | Class D Shares | Morgan Stanley Capital International All Country World Index℠ (net of foreign withholding taxes) (reflects no deduction for expenses, fees, or taxes, except foreign withholding taxes)
Risk/Return:	rr_RiskReturnAbstract
Label	rr_AverageAnnualReturnLabel	Morgan Stanley Capital International All Country World IndexSM (net of foreign withholding taxes)
1 Year	rr_AverageAnnualReturnYear01	16.13%
5 Years	rr_AverageAnnualReturnYear05	(1.16%)
Since Inception	rr_AverageAnnualReturnSinceInception	3.52%
Inception Date	rr_AverageAnnualReturnInceptionDate	Dec. 30, 2005
Janus Global Allocation Fund - Growth | Class D Shares | Global Growth Allocation Index (reflects no deduction for expenses, fees, or taxes, except any applicable foreign withholding taxes)
Risk/Return:	rr_RiskReturnAbstract
Label	rr_AverageAnnualReturnLabel	Global Growth Allocation Index
1 Year	rr_AverageAnnualReturnYear01	13.80%
5 Years	rr_AverageAnnualReturnYear05	0.43%
Since Inception	rr_AverageAnnualReturnSinceInception	4.30%
Inception Date	rr_AverageAnnualReturnInceptionDate	Dec. 30, 2005
Janus Global Allocation Fund - Growth | Class D Shares | S&P 500® Index (reflects no deduction for expenses, fees, or taxes)
Risk/Return:	rr_RiskReturnAbstract
Label	rr_AverageAnnualReturnLabel	S&P 500® Index
1 Year	rr_AverageAnnualReturnYear01	16.00%
5 Years	rr_AverageAnnualReturnYear05	1.66%
Since Inception	rr_AverageAnnualReturnSinceInception	4.12%
Inception Date	rr_AverageAnnualReturnInceptionDate	Dec. 30, 2005
Janus Global Allocation Fund - Growth | Class D Shares | Growth Allocation Index (reflects no deduction for expenses, fees, or taxes, except any applicable foreign withholding taxes)
Risk/Return:	rr_RiskReturnAbstract
Label	rr_AverageAnnualReturnLabel	Growth Allocation Index
1 Year	rr_AverageAnnualReturnYear01	14.29%
5 Years	rr_AverageAnnualReturnYear05	1.76%
Since Inception	rr_AverageAnnualReturnSinceInception	4.81%
Inception Date	rr_AverageAnnualReturnInceptionDate	Dec. 30, 2005

[1] If the Fund incurs a loss, which generates a tax benefit, the Return After Taxes on Distributions and Sale of Fund Shares may exceed the Fund’s other return figures.

XML

Label	Element	Value
Risk/Return:	rr_RiskReturnAbstract
Registrant Name	dei_EntityRegistrantName	JANUS INVESTMENT FUND
Prospectus Date	rr_ProspectusDate	Oct. 28, 2013
Janus Global Bond Fund | Class A, C, S, I, N, T Shares
Risk/Return:	rr_RiskReturnAbstract
Risk/Return [Heading]	rr_RiskReturnHeading	FUND SUMMARY Janus Global Bond Fund
Objective [Heading]	rr_ObjectiveHeading	INVESTMENT OBJECTIVE
Objective, Primary [Text Block]	rr_ObjectivePrimaryTextBlock	Janus Global Bond Fund seeks total return, consistent with preservation of capital.
Expense [Heading]	rr_ExpenseHeading	FEES AND EXPENSES OF THE FUND
Expense Narrative [Text Block]	rr_ExpenseNarrativeTextBlock	This table describes the fees and expenses that you may pay if you buy and hold Shares of the Fund. Each share class has different expenses, but represents an investment in the same Fund.
Shareholder Fees Caption [Text]	rr_ShareholderFeesCaption	SHAREHOLDER FEES (fees paid directly from your investment)
Operating Expenses Caption [Text]	rr_OperatingExpensesCaption	ANNUAL FUND OPERATING EXPENSES (expenses that you pay each year as a percentage of the value of your investment)
Fee Waiver or Reimbursement over Assets, Date of Termination	rr_FeeWaiverOrReimbursementOverAssetsDateOfTermination	November 1, 2014
Portfolio Turnover [Heading]	rr_PortfolioTurnoverHeading	Portfolio Turnover:
Portfolio Turnover [Text Block]	rr_PortfolioTurnoverTextBlock	The Fund pays transaction costs, such as commissions, when it buys and sells securities (or “turns over” its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when Fund shares are held in a taxable account. These costs, which are not reflected in annual fund operating expenses or in the Example, affect the Fund’s performance. During the most recent fiscal year, the Fund’s portfolio turnover rate was 182% of the average value of its portfolio.
Portfolio Turnover, Rate	rr_PortfolioTurnoverRate	182.00%
Expense Breakpoint Discounts [Text]	rr_ExpenseBreakpointDiscounts	For Class A Shares, you may qualify for sales charge discounts if you and your family invest, or agree to invest in the future, at least $50,000 in the Fund or in other Janus mutual funds. More information about these and other discounts, as well as eligibility requirements for each share class, is available from your financial professional and in the “Purchases” section on page 64 of the Fund’s Prospectus and in the “Purchases” section on page 70 of the Fund’s Statement of Additional Information.
Expense Breakpoint, Minimum Investment Required [Amount]	rr_ExpenseBreakpointMinimumInvestmentRequiredAmount	$ 50,000
Expense Example [Heading]	rr_ExpenseExampleHeading	EXAMPLE:
Expense Example by Year [Heading]	rr_ExpenseExampleByYearHeading	The Example assumes that you invest $10,000 in the Fund for the time periods indicated and reinvest all dividends and distributions. The Example also assumes that your investment has a 5% return each year and that the Fund’s operating expenses without waivers or recoupments (if applicable) remain the same. Although your actual costs may be higher or lower, based on these assumptions your costs would be:
Expense Example Narrative [Text Block]	rr_ExpenseExampleNarrativeTextBlock	The following Example is based on expenses without waivers. The Example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds.
Expense Example by, Year, Caption [Text]	rr_ExpenseExampleByYearCaption	If Shares are redeemed:
Expense Example, No Redemption, By Year, Caption [Text]	rr_ExpenseExampleNoRedemptionByYearCaption	If Shares are not redeemed:
Strategy [Heading]	rr_StrategyHeading	PRINCIPAL INVESTMENT STRATEGIES
Strategy Narrative [Text Block]	rr_StrategyNarrativeTextBlock	The Fund pursues its investment objective by investing, under normal circumstances, at least 80% of its net assets in bonds. Bonds include, but are not limited to, corporate bonds, government notes and bonds, convertible bonds, mortgage-backed securities, and zero-coupon bonds. The Fund invests in corporate debt securities of issuers in a number of different countries, which may include the United States. The Fund invests in securities of issuers that are economically tied to developed and emerging market countries. The Fund may invest across all fixed-income sectors, including U.S. and non-U.S. government securities. The Fund’s investments may be denominated in local currency or U.S. dollar-denominated. The Fund may invest in debt securities with a range of maturities from short- to long-term. The Fund may invest up to 35% of its net assets in high-yield/high-risk debt securities. The Fund may also invest in preferred and common stock, money market instruments, municipal bonds, commercial and residential mortgage-backed securities, asset-backed securities, other securitized and structured debt products, private placements, and other investment companies, including exchange-traded funds (“ETFs”). The Fund may also invest in bank loans, euro-denominated obligations, buy backs or dollar rolls, when-issued securities, and reverse repurchase agreements. Due to the nature of securities in which the Fund invests, it may have relatively high portfolio turnover compared to other funds. In addition, the Fund may invest its assets in derivatives, which are instruments that have a value derived from, or directly linked to, an underlying asset, such as equity securities, fixed-income securities, commodities, currencies, interest rates, or market indices, as substitutes for securities in which the Fund invests. The Fund has invested in and is expected to continue to invest in collateralized forward foreign currency exchange contracts, futures, options, and swaps (including interest rate swaps, total return swaps, and credit default swaps) for hedging purposes (to offset risks associated with an investment, currency exposure, or market conditions) and to increase or decrease the Fund’s exposure to a particular market, to manage or adjust the risk profile of the Fund related to an investment or currency exposure, to adjust its currency exposure relative to its benchmark index, and to earn income and enhance returns. In particular, the Fund may use interest rate futures to manage portfolio risk. The Fund’s exposure to derivatives will vary, is not limited to those derivatives listed, and could be significant at times. For purposes of meeting its 80% investment policy, the Fund may include derivatives that have characteristics similar to the securities in which the Fund may directly invest. In addition to considering economic factors such as the effect of interest rates on the Fund’s investments, the portfolio managers apply a “bottom up” approach in choosing investments. This means that the portfolio managers look at income-producing securities one at a time to determine if a security is an attractive investment opportunity and if it is consistent with the Fund’s investment policies. The Fund may lend portfolio securities on a short-term or long-term basis, in an amount equal to up to 1/3 of its total assets as determined at the time of the loan origination.
Risk [Heading]	rr_RiskHeading	PRINCIPAL INVESTMENT RISKS
Risk Narrative [Text Block]	rr_RiskNarrativeTextBlock	Although the Fund may be less volatile than funds that invest most of their assets in common stocks, the Fund’s returns and yields will vary, and you could lose money. Fixed-Income Securities Risk. The Fund invests in a variety of fixed-income securities. Typically, the values of fixed-income securities change inversely with prevailing interest rates. Therefore, a fundamental risk of fixed-income securities is interest rate risk, which is the risk that the value of such securities will generally decline as prevailing interest rates rise, which may cause the Fund’s net asset value to likewise decrease. How specific fixed-income securities may react to changes in interest rates will depend on the specific characteristics of each security. Fixed-income securities are also subject to credit risk, prepayment risk, valuation risk, and liquidity risk. Credit risk is the risk that the credit strength of an issuer of a fixed-income security will weaken and/or that the issuer will be unable to make timely principal and interest payments and that the security may go into default. Prepayment risk is the risk that during periods of falling interest rates, certain fixed-income securities with higher interest rates, such as mortgage- and asset-backed securities, may be prepaid by their issuers thereby reducing the amount of interest payments. Valuation risk is the risk that one or more of the fixed-income securities in which the Fund invests are priced differently than the value realized upon such security’s sale. In times of market instability, valuation may be more difficult. Liquidity risk is the risk that fixed-income securities may be difficult or impossible to sell at the time that the portfolio managers would like or at the price the portfolio managers believe the security is currently worth. Foreign Exposure Risk. The Fund normally has significant exposure to foreign markets as a result of its investments in foreign securities, including investments in emerging markets, which can be more volatile than the U.S. markets. As a result, its returns and net asset value may be affected to a large degree by fluctuations in currency exchange rates or political or economic conditions in a particular country. In some foreign markets, there may not be protection against failure by other parties to complete transactions. It may not be possible for the Fund to repatriate capital, dividends, interest, and other income from a particular country or governmental entity. In addition, a market swing in one or more countries or regions where the Fund has invested a significant amount of its assets may have a greater effect on the Fund’s performance than it would in a more geographically diversified portfolio. The Fund’s investments in emerging market countries may involve risks greater than, or in addition to, the risks of investing in more developed countries. To the extent the Fund invests in foreign debt securities, such investments are sensitive to changes in interest rates. Additionally, investments in securities of foreign governments involve the risk that a foreign government may not be willing or able to pay interest or repay principal when due. Eurozone Risk. A number of countries in the European Union (“EU”) have experienced severe economic and financial difficulties. As a result, financial markets in the EU have been subject to extreme volatility and declines in asset values and liquidity. Responses to these financial problems by European governments, central banks, and others, including austerity measures and reforms, may not work, may result in social unrest, and may limit future growth and economic recovery or have other unintended consequences. Further defaults or restructurings by governments and others of their debt could have additional adverse effects on economies, financial markets, and asset valuations around the world. To the extent that the Fund has exposure to European markets or to transactions tied to the value of the euro, these events could negatively affect the value and liquidity of the Fund’s investments. Emerging Markets Risk. The risks of foreign investing mentioned above are heightened when investing in emerging markets. Emerging markets securities involve a number of additional risks, which may result from less government supervision and regulation of business and industry practices (including the potential lack of strict finance and accounting controls and standards), stock exchanges, brokers, and listed companies, making these investments potentially more volatile in price and less liquid than investments in developed securities markets, resulting in greater risk to investors. There is a risk in developing countries that a future economic or political crisis could lead to price controls, forced mergers of companies, expropriation or confiscatory taxation, imposition or enforcement of foreign ownership limits, seizure, nationalization, or creation of government monopolies, any of which may have a detrimental effect on the Fund’s investments. In addition, the Fund’s investments may be denominated in foreign currencies and therefore, changes in the value of a country’s currency compared to the U.S. dollar may affect the value of the Fund’s investments. To the extent that the Fund invests a significant portion of its assets in the securities of issuers in or companies of a single country or region, it is more likely to be impacted by events or conditions affecting that country or region, which could have a negative impact on the Fund’s performance. Some of the risks of investing directly in foreign and emerging market securities may be reduced when the Fund invests indirectly in foreign securities through various other investment vehicles including derivatives, which also involve other risks. As of June 30, 2013, approximately 4.2% of the Fund’s investments were in emerging markets. Mortgage-Backed Securities Risk. Mortgage-backed securities are classified generally as either commercial mortgage-backed securities or residential mortgage-backed securities, each of which is subject to certain specific risks. Mortgage-backed securities tend to be more sensitive to changes in interest rates than other types of debt securities. Investments in mortgage-backed securities are subject to both extension risk, where borrowers extend the duration of their mortgages in times of rising interest rates, and prepayment risk, where borrowers pay off their mortgages sooner than expected in times of declining interest rates. These risks may reduce the Fund’s returns. In addition, investments in mortgage-backed securities, including those comprised of subprime mortgages, may be subject to a higher degree of credit risk, valuation risk, and liquidity risk than various other types of fixed-income securities. Sovereign Debt Risk. The Fund may invest in U.S. and foreign government debt securities (“sovereign debt”). Investments in U.S. sovereign debt are considered low risk. However, investments in non-U.S. sovereign debt can involve a high degree of risk, including the risk that the governmental entity that controls the repayment of sovereign debt may not be willing or able to repay the principal and/or to pay the interest on its sovereign debt in a timely manner. A sovereign debtor’s willingness or ability to satisfy its debt obligation may be affected by various factors including, but not limited to, its cash flow situation, the extent of its foreign currency reserves, the availability of foreign exchange when a payment is due, and the relative size of its debt position in relation to its economy as a whole. In the event of default, there may be limited or no legal remedies for collecting sovereign debt and there may be no bankruptcy proceedings through which the Fund may collect all or part of the sovereign debt that a governmental entity has not repaid. High-Yield/High-Risk Bond Risk. High-yield/high-risk bonds (also known as “junk” bonds) may be more sensitive than other types of bonds to economic changes, political changes, or adverse developments specific to the company that issued the bond, which may adversely affect their value. Bank Loan Risk. Bank loans are obligations of companies or other entities entered into in connection with recapitalizations, acquisitions, and refinancings. The Fund’s investments in bank loans are generally acquired as a participation interest in, or assignment of, loans originated by a lender or other financial institution. These investments may include institutionally-traded floating and fixed-rate debt securities. Participation interests and assignments involve credit, interest rate, and liquidity risk. In addition, the bank loans underlying these securities often involve borrowers with low credit ratings whose financial conditions are troubled or uncertain, including companies that are highly leveraged or in bankruptcy proceedings. Exchange-Traded Funds Risk. The Fund may purchase shares of exchange-traded funds (“ETFs”) to gain exposure to a particular portion of the market. ETFs are pooled investment vehicles, which may be managed or unmanaged, that generally seek to track the performance of a specific index. ETFs are traded on an exchange at market prices that may vary from the net asset value of their underlying investments. When the Fund invests in an ETF, in addition to directly bearing the expenses associated with its own operations, it will bear a pro rata portion of the ETF’s expenses. ETFs have certain inherent risks generally associated with investments in a portfolio of securities in which the ETF is invested, including the risk that the general level of stock prices may decline, thereby adversely affecting the value of each unit of the ETF. ETFs also involve the risk that an active trading market for an ETF’s shares may not develop or be maintained. Derivatives Risk. Derivatives can be highly volatile and involve risks in addition to the risks of the underlying referenced securities. Gains or losses from a derivative investment can be substantially greater than the derivative’s original cost, and can therefore involve leverage. Leverage may cause the Fund to be more volatile than if it had not used leverage. Derivatives can be complex instruments and may involve analysis that differs from that required for other investment types used by the Fund. If the value of a derivative does not correlate well with the particular market or other asset class to which the derivative is intended to provide exposure, the derivative may not produce the anticipated result. Derivatives can also reduce the opportunity for gain or result in losses by offsetting positive returns in other investments. Derivatives can be less liquid than other types of investments and entail the risk that the counterparty will default on its payment obligations. If the counterparty to a derivative transaction defaults, the Fund would risk the loss of the net amount of the payments that it contractually is entitled to receive. To the extent the Fund enters into short derivative positions, the Fund may be exposed to risks similar to those associated with short sales, including the risk that the Fund’s losses are theoretically unlimited. Portfolio Turnover Risk. Increased portfolio turnover may result in higher costs, which may have a negative effect on the Fund’s performance. In addition, higher portfolio turnover may result in the acceleration of capital gains and the recognition of greater levels of short-term capital gains, which are taxed at ordinary federal income tax rates when distributed to shareholders. Securities Lending Risk. The Fund may seek to earn additional income through lending its securities to certain qualified broker-dealers and institutions. There is the risk that when portfolio securities are lent, the securities may not be returned on a timely basis, and the Fund may experience delays and costs in recovering the security or gaining access to the collateral provided to the Fund to collateralize the loan. If the Fund is unable to recover a security on loan, the Fund may use the collateral to purchase replacement securities in the market. There is a risk that the value of the collateral could decrease below the cost of the replacement security by the time the replacement investment is made, resulting in a loss to the Fund. An investment in the Fund is not a bank deposit and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency.
Risk Lose Money [Text]	rr_RiskLoseMoney	Although the Fund may be less volatile than funds that invest most of their assets in common stocks, the Fund’s returns and yields will vary, and you could lose money.
Risk Not Insured Depository Institution [Text]	rr_RiskNotInsuredDepositoryInstitution	An investment in the Fund is not a bank deposit and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency.
Bar Chart and Performance Table [Heading]	rr_BarChartAndPerformanceTableHeading	PERFORMANCE INFORMATION
Performance Narrative [Text Block]	rr_PerformanceNarrativeTextBlock	The following information provides some indication of the risks of investing in the Fund by showing how the Fund’s performance has varied over time. Class A Shares, Class C Shares, Class S Shares, Class I Shares, and Class T Shares of the Fund commenced operations with the Fund’s inception. Class N Shares of the Fund commenced operations on October 28, 2013. The performance shown for Class A Shares, Class C Shares, Class S Shares, Class I Shares, and Class T Shares is calculated using the fees and expenses of each respective share class, net of any applicable fee and expense limitations or waivers. The performance shown for Class N Shares for periods prior to December 31, 2012, reflects the performance of the Fund’s Class I Shares, calculated using the fees and expenses of Class N Shares, without the effect of any fee and expense limitations or waivers. If Class N Shares of the Fund had been available during periods prior to December 31, 2012, the performance shown may have been different. The bar chart depicts the change in performance from year to year during the periods indicated. The bar chart figures do not include any applicable sales charges that an investor may pay when they buy or sell Class A Shares or Class C Shares of the Fund. If sales charges were included, the returns would be lower. The table compares the Fund’s average annual returns for the periods indicated to broad-based securities market indices. The indices are not actively managed and are not available for direct investment. All figures assume reinvestment of dividends and distributions. For certain periods, the Fund’s performance reflects the effect of expense waivers. Without the effect of these expense waivers, the performance shown would have been lower. The Fund’s past performance (before and after taxes) does not necessarily indicate how it will perform in the future. Updated performance information is available at janus.com/advisor/mutual-funds or by calling 1-877-335-2687.
Performance Information Illustrates Variability of Returns [Text]	rr_PerformanceInformationIllustratesVariabilityOfReturns	The following information provides some indication of the risks of investing in the Fund by showing how the Fund’s performance has varied over time. The bar chart depicts the change in performance from year to year during the periods indicated.
Performance Additional Market Index [Text]	rr_PerformanceAdditionalMarketIndex	The table compares the Fund’s average annual returns for the periods indicated to broad-based securities market indices. The indices are not actively managed and are not available for direct investment. All figures assume reinvestment of dividends and distributions.
Performance Availability Phone [Text]	rr_PerformanceAvailabilityPhone	1-877-335-2687
Performance Availability Website Address [Text]	rr_PerformanceAvailabilityWebSiteAddress	janus.com/advisor/mutual-funds
Performance Past Does Not Indicate Future [Text]	rr_PerformancePastDoesNotIndicateFuture	The Fund’s past performance (before and after taxes) does not necessarily indicate how it will perform in the future.
Bar Chart [Heading]	rr_BarChartHeading	Annual Total Returns for Class I Shares (calendar year-end)
Bar Chart Does Not Reflect Sales Loads [Text]	rr_BarChartDoesNotReflectSalesLoads	The bar chart figures do not include any applicable sales charges that an investor may pay when they buy or sell Class A Shares or Class C Shares of the Fund. If sales charges were included, the returns would be lower.
Bar Chart Closing [Text Block]	rr_BarChartClosingTextBlock	Best Quarter:  Third Quarter 2012  4.26%          Worst Quarter:  Fourth Quarter 2012  0.32%
Year to Date Return, Label	rr_YearToDateReturnLabel	The Fund’s year-to-date return as of the calendar quarter ended September 30, 2013 was −3.22%.
Performance Table Heading	rr_PerformanceTableHeading	Average Annual Total Returns (periods ended 12/31/12)
Performance Table Uses Highest Federal Rate	rr_PerformanceTableUsesHighestFederalRate	After-tax returns are calculated using the historically highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes.
Performance Table Not Relevant to Tax Deferred	rr_PerformanceTableNotRelevantToTaxDeferred	Actual after-tax returns depend on your individual tax situation and may differ from those shown in the preceding table. The after-tax return information shown above does not apply to Fund shares held through a tax-deferred account, such as a 401(k) plan or an IRA.
Performance Table One Class of after Tax Shown [Text]	rr_PerformanceTableOneClassOfAfterTaxShown	After-tax returns are only shown for Class I Shares of the Fund. After-tax returns for the other classes of Shares will vary from those shown for Class I Shares due to varying sales charges (as applicable), fees, and expenses among the classes.
Performance Table Narrative	rr_PerformanceTableNarrativeTextBlock	After-tax returns are calculated using the historically highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes. Actual after-tax returns depend on your individual tax situation and may differ from those shown in the preceding table. The after-tax return information shown above does not apply to Fund shares held through a tax-deferred account, such as a 401(k) plan or an IRA. After-tax returns are only shown for Class I Shares of the Fund. After-tax returns for the other classes of Shares will vary from those shown for Class I Shares due to varying sales charges (as applicable), fees, and expenses among the classes.
Performance Table Closing [Text Block]	rr_PerformanceTableClosingTextBlock	Updated performance information is available at janus.com/advisor/mutual-funds or by calling 1-877-335-2687.
Janus Global Bond Fund | Class A, C, S, I, N, T Shares | Class A
Risk/Return:	rr_RiskReturnAbstract
Shareholder Fees Column [Text]	rr_ShareholderFeesColumnName	Class A
Maximum Sales Charge (load) Imposed on Purchases (as a percentage of offering price)	rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice	4.75%
Maximum Deferred Sales Charge (load) (as a percentage of the lower of original purchase price or redemption proceeds)	rr_MaximumDeferredSalesChargeOverOther	none
Operating Expenses Column [Text]	rr_OperatingExpensesColumnName	Class A
Management Fees	rr_ManagementFeesOverAssets	0.60%
Distribution/Service (12b-1) Fees	rr_DistributionAndService12b1FeesOverAssets	0.25%
Other Expenses	rr_OtherExpensesOverAssets	0.24%	[1]
Total Annual Fund Operating Expenses	rr_ExpensesOverAssets	1.09%	[2]
Fee Waiver	rr_FeeWaiverOrReimbursementOverAssets	0.06%	[2]
Total Annual Fund Operating Expenses After Fee Waiver	rr_NetExpensesOverAssets	1.03%	[2]
Expense Example, By Year, Column [Text]	rr_ExpenseExampleByYearColumnName	Class A Shares
1 Year	rr_ExpenseExampleYear01	581
3 Years	rr_ExpenseExampleYear03	805
5 Years	rr_ExpenseExampleYear05	1,047
10 Years	rr_ExpenseExampleYear10	1,741
Expense Example, No Redemption, By Year, Column [Text]	rr_ExpenseExampleNoRedemptionByYearColumnName	Class A Shares
1 Year	rr_ExpenseExampleNoRedemptionYear01	581
3 Years	rr_ExpenseExampleNoRedemptionYear03	805
5 Years	rr_ExpenseExampleNoRedemptionYear05	1,047
10 Years	rr_ExpenseExampleNoRedemptionYear10	1,741
Janus Global Bond Fund | Class A, C, S, I, N, T Shares | Class C
Risk/Return:	rr_RiskReturnAbstract
Shareholder Fees Column [Text]	rr_ShareholderFeesColumnName	Class C
Maximum Sales Charge (load) Imposed on Purchases (as a percentage of offering price)	rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice	none
Maximum Deferred Sales Charge (load) (as a percentage of the lower of original purchase price or redemption proceeds)	rr_MaximumDeferredSalesChargeOverOther	1.00%
Operating Expenses Column [Text]	rr_OperatingExpensesColumnName	Class C
Management Fees	rr_ManagementFeesOverAssets	0.60%
Distribution/Service (12b-1) Fees	rr_DistributionAndService12b1FeesOverAssets	1.00%
Other Expenses	rr_OtherExpensesOverAssets	0.25%	[1]
Total Annual Fund Operating Expenses	rr_ExpensesOverAssets	1.85%	[2]
Fee Waiver	rr_FeeWaiverOrReimbursementOverAssets	0.08%	[2]
Total Annual Fund Operating Expenses After Fee Waiver	rr_NetExpensesOverAssets	1.77%	[2]
Expense Example, By Year, Column [Text]	rr_ExpenseExampleByYearColumnName	Class C Shares
1 Year	rr_ExpenseExampleYear01	288
3 Years	rr_ExpenseExampleYear03	582
5 Years	rr_ExpenseExampleYear05	1,001
10 Years	rr_ExpenseExampleYear10	2,169
Expense Example, No Redemption, By Year, Column [Text]	rr_ExpenseExampleNoRedemptionByYearColumnName	Class C Shares
1 Year	rr_ExpenseExampleNoRedemptionYear01	188
3 Years	rr_ExpenseExampleNoRedemptionYear03	582
5 Years	rr_ExpenseExampleNoRedemptionYear05	1,001
10 Years	rr_ExpenseExampleNoRedemptionYear10	2,169
Janus Global Bond Fund | Class A, C, S, I, N, T Shares | Class S
Risk/Return:	rr_RiskReturnAbstract
Shareholder Fees Column [Text]	rr_ShareholderFeesColumnName	Class S
Maximum Sales Charge (load) Imposed on Purchases (as a percentage of offering price)	rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice	none
Maximum Deferred Sales Charge (load) (as a percentage of the lower of original purchase price or redemption proceeds)	rr_MaximumDeferredSalesChargeOverOther	none
Operating Expenses Column [Text]	rr_OperatingExpensesColumnName	Class S
Management Fees	rr_ManagementFeesOverAssets	0.60%
Distribution/Service (12b-1) Fees	rr_DistributionAndService12b1FeesOverAssets	0.25%
Other Expenses	rr_OtherExpensesOverAssets	0.45%	[1]
Total Annual Fund Operating Expenses	rr_ExpensesOverAssets	1.30%	[2]
Fee Waiver	rr_FeeWaiverOrReimbursementOverAssets	0.05%	[2]
Total Annual Fund Operating Expenses After Fee Waiver	rr_NetExpensesOverAssets	1.25%	[2]
Expense Example, By Year, Column [Text]	rr_ExpenseExampleByYearColumnName	Class S Shares
1 Year	rr_ExpenseExampleYear01	132
3 Years	rr_ExpenseExampleYear03	412
5 Years	rr_ExpenseExampleYear05	713
10 Years	rr_ExpenseExampleYear10	1,568
Expense Example, No Redemption, By Year, Column [Text]	rr_ExpenseExampleNoRedemptionByYearColumnName	Class S Shares
1 Year	rr_ExpenseExampleNoRedemptionYear01	132
3 Years	rr_ExpenseExampleNoRedemptionYear03	412
5 Years	rr_ExpenseExampleNoRedemptionYear05	713
10 Years	rr_ExpenseExampleNoRedemptionYear10	1,568
Janus Global Bond Fund | Class A, C, S, I, N, T Shares | Class I
Risk/Return:	rr_RiskReturnAbstract
Shareholder Fees Column [Text]	rr_ShareholderFeesColumnName	Class I
Maximum Sales Charge (load) Imposed on Purchases (as a percentage of offering price)	rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice	none
Maximum Deferred Sales Charge (load) (as a percentage of the lower of original purchase price or redemption proceeds)	rr_MaximumDeferredSalesChargeOverOther	none
Operating Expenses Column [Text]	rr_OperatingExpensesColumnName	Class I
Management Fees	rr_ManagementFeesOverAssets	0.60%
Distribution/Service (12b-1) Fees	rr_DistributionAndService12b1FeesOverAssets	none
Other Expenses	rr_OtherExpensesOverAssets	0.20%	[1]
Total Annual Fund Operating Expenses	rr_ExpensesOverAssets	0.80%	[2]
Fee Waiver	rr_FeeWaiverOrReimbursementOverAssets	0.05%	[2]
Total Annual Fund Operating Expenses After Fee Waiver	rr_NetExpensesOverAssets	0.75%	[2]
Expense Example, By Year, Column [Text]	rr_ExpenseExampleByYearColumnName	Class I Shares
1 Year	rr_ExpenseExampleYear01	82
3 Years	rr_ExpenseExampleYear03	255
5 Years	rr_ExpenseExampleYear05	444
10 Years	rr_ExpenseExampleYear10	990
Expense Example, No Redemption, By Year, Column [Text]	rr_ExpenseExampleNoRedemptionByYearColumnName	Class I Shares
1 Year	rr_ExpenseExampleNoRedemptionYear01	82
3 Years	rr_ExpenseExampleNoRedemptionYear03	255
5 Years	rr_ExpenseExampleNoRedemptionYear05	444
10 Years	rr_ExpenseExampleNoRedemptionYear10	990
2011	rr_AnnualReturn2011	6.67%
2012	rr_AnnualReturn2012	8.28%
Bar Chart, Year to Date Return, Date	rr_BarChartYearToDateReturnDate	Sep. 30, 2013
Bar Chart, Year to Date Return	rr_BarChartYearToDateReturn	(3.22%)
Highest Quarterly Return, Label	rr_HighestQuarterlyReturnLabel	Best Quarter:
Highest Quarterly Return, Date	rr_BarChartHighestQuarterlyReturnDate	Sep. 30, 2012
Highest Quarterly Return	rr_BarChartHighestQuarterlyReturn	4.26%
Lowest Quarterly Return, Label	rr_LowestQuarterlyReturnLabel	Worst Quarter:
Lowest Quarterly Return, Date	rr_BarChartLowestQuarterlyReturnDate	Dec. 31, 2012
Lowest Quarterly Return	rr_BarChartLowestQuarterlyReturn	0.32%
Janus Global Bond Fund | Class A, C, S, I, N, T Shares | Class N
Risk/Return:	rr_RiskReturnAbstract
Shareholder Fees Column [Text]	rr_ShareholderFeesColumnName	Class N
Maximum Sales Charge (load) Imposed on Purchases (as a percentage of offering price)	rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice	none
Maximum Deferred Sales Charge (load) (as a percentage of the lower of original purchase price or redemption proceeds)	rr_MaximumDeferredSalesChargeOverOther	none
Operating Expenses Column [Text]	rr_OperatingExpensesColumnName	Class N
Management Fees	rr_ManagementFeesOverAssets	0.60%
Distribution/Service (12b-1) Fees	rr_DistributionAndService12b1FeesOverAssets	none
Other Expenses	rr_OtherExpensesOverAssets	0.20%	[1]
Total Annual Fund Operating Expenses	rr_ExpensesOverAssets	0.80%	[2]
Fee Waiver	rr_FeeWaiverOrReimbursementOverAssets	0.05%	[2]
Total Annual Fund Operating Expenses After Fee Waiver	rr_NetExpensesOverAssets	0.75%	[2]
Expense Example, By Year, Column [Text]	rr_ExpenseExampleByYearColumnName	Class N Shares
1 Year	rr_ExpenseExampleYear01	82
3 Years	rr_ExpenseExampleYear03	255
5 Years	rr_ExpenseExampleYear05	444
10 Years	rr_ExpenseExampleYear10	990
Expense Example, No Redemption, By Year, Column [Text]	rr_ExpenseExampleNoRedemptionByYearColumnName	Class N Shares
1 Year	rr_ExpenseExampleNoRedemptionYear01	82
3 Years	rr_ExpenseExampleNoRedemptionYear03	255
5 Years	rr_ExpenseExampleNoRedemptionYear05	444
10 Years	rr_ExpenseExampleNoRedemptionYear10	990
Janus Global Bond Fund | Class A, C, S, I, N, T Shares | Class T
Risk/Return:	rr_RiskReturnAbstract
Shareholder Fees Column [Text]	rr_ShareholderFeesColumnName	Class T
Maximum Sales Charge (load) Imposed on Purchases (as a percentage of offering price)	rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice	none
Maximum Deferred Sales Charge (load) (as a percentage of the lower of original purchase price or redemption proceeds)	rr_MaximumDeferredSalesChargeOverOther	none
Operating Expenses Column [Text]	rr_OperatingExpensesColumnName	Class T
Management Fees	rr_ManagementFeesOverAssets	0.60%
Distribution/Service (12b-1) Fees	rr_DistributionAndService12b1FeesOverAssets	none
Other Expenses	rr_OtherExpensesOverAssets	0.45%	[1]
Total Annual Fund Operating Expenses	rr_ExpensesOverAssets	1.05%	[2]
Fee Waiver	rr_FeeWaiverOrReimbursementOverAssets	0.05%	[2]
Total Annual Fund Operating Expenses After Fee Waiver	rr_NetExpensesOverAssets	1.00%	[2]
Expense Example, By Year, Column [Text]	rr_ExpenseExampleByYearColumnName	Class T Shares
1 Year	rr_ExpenseExampleYear01	107
3 Years	rr_ExpenseExampleYear03	334
5 Years	rr_ExpenseExampleYear05	579
10 Years	rr_ExpenseExampleYear10	1,283
Expense Example, No Redemption, By Year, Column [Text]	rr_ExpenseExampleNoRedemptionByYearColumnName	Class T Shares
1 Year	rr_ExpenseExampleNoRedemptionYear01	107
3 Years	rr_ExpenseExampleNoRedemptionYear03	334
5 Years	rr_ExpenseExampleNoRedemptionYear05	579
10 Years	rr_ExpenseExampleNoRedemptionYear10	$ 1,283
Janus Global Bond Fund | Class A, C, S, I, N, T Shares | Return Before Taxes | Class A
Risk/Return:	rr_RiskReturnAbstract
Column	rr_AverageAnnualReturnColumnName	Class A Shares
Label	rr_AverageAnnualReturnLabel	Return Before Taxes	[3]
1 Year	rr_AverageAnnualReturnYear01	2.91%
Since Inception	rr_AverageAnnualReturnSinceInception	4.66%
Inception Date	rr_AverageAnnualReturnInceptionDate	Dec. 28, 2010
Janus Global Bond Fund | Class A, C, S, I, N, T Shares | Return Before Taxes | Class C
Risk/Return:	rr_RiskReturnAbstract
Column	rr_AverageAnnualReturnColumnName	Class C Shares
Label	rr_AverageAnnualReturnLabel	Return Before Taxes	[4]
1 Year	rr_AverageAnnualReturnYear01	6.19%
Since Inception	rr_AverageAnnualReturnSinceInception	6.48%
Inception Date	rr_AverageAnnualReturnInceptionDate	Dec. 28, 2010
Janus Global Bond Fund | Class A, C, S, I, N, T Shares | Return Before Taxes | Class S
Risk/Return:	rr_RiskReturnAbstract
Column	rr_AverageAnnualReturnColumnName	Class S Shares
Label	rr_AverageAnnualReturnLabel	Return Before Taxes
1 Year	rr_AverageAnnualReturnYear01	7.81%
Since Inception	rr_AverageAnnualReturnSinceInception	7.04%
Inception Date	rr_AverageAnnualReturnInceptionDate	Dec. 28, 2010
Janus Global Bond Fund | Class A, C, S, I, N, T Shares | Return Before Taxes | Class I
Risk/Return:	rr_RiskReturnAbstract
Column	rr_AverageAnnualReturnColumnName	Class I Shares
Label	rr_AverageAnnualReturnLabel	Return Before Taxes
1 Year	rr_AverageAnnualReturnYear01	8.28%
Since Inception	rr_AverageAnnualReturnSinceInception	7.44%
Inception Date	rr_AverageAnnualReturnInceptionDate	Dec. 28, 2010
Janus Global Bond Fund | Class A, C, S, I, N, T Shares | Return Before Taxes | Class N
Risk/Return:	rr_RiskReturnAbstract
Column	rr_AverageAnnualReturnColumnName	Class N Shares
Label	rr_AverageAnnualReturnLabel	Return Before Taxes
1 Year	rr_AverageAnnualReturnYear01	7.87%
Since Inception	rr_AverageAnnualReturnSinceInception	7.04%
Inception Date	rr_AverageAnnualReturnInceptionDate	Dec. 28, 2010
Janus Global Bond Fund | Class A, C, S, I, N, T Shares | Return Before Taxes | Class T
Risk/Return:	rr_RiskReturnAbstract
Column	rr_AverageAnnualReturnColumnName	Class T Shares
Label	rr_AverageAnnualReturnLabel	Return Before Taxes
1 Year	rr_AverageAnnualReturnYear01	8.03%
Since Inception	rr_AverageAnnualReturnSinceInception	7.24%
Inception Date	rr_AverageAnnualReturnInceptionDate	Dec. 28, 2010
Janus Global Bond Fund | Class A, C, S, I, N, T Shares | Return After Taxes on Distributions | Class I
Risk/Return:	rr_RiskReturnAbstract
Column	rr_AverageAnnualReturnColumnName	Class I Shares
Label	rr_AverageAnnualReturnLabel	Return After Taxes on Distributions
1 Year	rr_AverageAnnualReturnYear01	6.39%
Since Inception	rr_AverageAnnualReturnSinceInception	5.81%
Inception Date	rr_AverageAnnualReturnInceptionDate	Dec. 28, 2010
Janus Global Bond Fund | Class A, C, S, I, N, T Shares | Return After Taxes on Distributions and Sale of Fund Shares | Class I
Risk/Return:	rr_RiskReturnAbstract
Column	rr_AverageAnnualReturnColumnName	Class I Shares
Label	rr_AverageAnnualReturnLabel	Return After Taxes on Distributions and Sale of Fund Shares
1 Year	rr_AverageAnnualReturnYear01	5.50%
Since Inception	rr_AverageAnnualReturnSinceInception	5.43%
Inception Date	rr_AverageAnnualReturnInceptionDate	Dec. 28, 2010
Janus Global Bond Fund | Class A, C, S, I, N, T Shares | Barclays Global Aggregate Bond Index (reflects no deduction for expenses, fees, or taxes)
Risk/Return:	rr_RiskReturnAbstract
Label	rr_AverageAnnualReturnLabel	Barclays Global Aggregate Bond Index
1 Year	rr_AverageAnnualReturnYear01	4.32%
Since Inception	rr_AverageAnnualReturnSinceInception	5.74%
Inception Date	rr_AverageAnnualReturnInceptionDate	Dec. 28, 2010
Janus Global Bond Fund | Class A, C, S, I, N, T Shares | Barclays Global Aggregate Corporate Bond Index (reflects no deduction for expenses, fees, or taxes)
Risk/Return:	rr_RiskReturnAbstract
Label	rr_AverageAnnualReturnLabel	Barclays Global Aggregate Corporate Bond Index
1 Year	rr_AverageAnnualReturnYear01	11.21%
Since Inception	rr_AverageAnnualReturnSinceInception	8.59%
Inception Date	rr_AverageAnnualReturnInceptionDate	Dec. 28, 2010

[1] Other Expenses are based on the estimated expenses that the Fund expects to incur.

[2] Janus Capital has contractually agreed to waive its investment advisory fee and/or reimburse Fund expenses to the extent that the Fund’s total annual fund operating expenses (excluding the distribution and shareholder servicing fees – applicable to Class A Shares, Class C Shares, and Class S Shares; administrative services fees payable pursuant to the Transfer Agency Agreement; brokerage commissions; interest; dividends; taxes; acquired fund fees and expenses; and extraordinary expenses) exceed 0.75% until at least November 1, 2014. The contractual waiver may be terminated or modified prior to this date only at the discretion of the Board of Trustees. For a period of three years subsequent to the Fund’s commencement of operations (December 28, 2010) or until the Fund’s assets exceed the first breakpoint in the investment advisory fee schedule, whichever occurs first, Janus Capital may recover from the Fund fees and expenses previously waived or reimbursed, which could then be considered a deferral, if the Fund’s expense ratio, including recovered expenses, falls below the expense limit.

[3] Calculated assuming maximum permitted sales loads.

[4] The one year return is calculated to include the contingent deferred sales charge.

XML

Label	Element	Value
Risk/Return:	rr_RiskReturnAbstract
Registrant Name	dei_EntityRegistrantName	JANUS INVESTMENT FUND
Prospectus Date	rr_ProspectusDate	Oct. 28, 2013
Janus Short-Term Bond Fund | Class A, C, S, I, N, T Shares
Risk/Return:	rr_RiskReturnAbstract
Risk/Return [Heading]	rr_RiskReturnHeading	FUND SUMMARY Janus Short-Term Bond Fund
Objective [Heading]	rr_ObjectiveHeading	INVESTMENT OBJECTIVE
Objective, Primary [Text Block]	rr_ObjectivePrimaryTextBlock	Janus Short-Term Bond Fund seeks as high a level of current income as is consistent with preservation of capital.
Expense [Heading]	rr_ExpenseHeading	FEES AND EXPENSES OF THE FUND
Expense Narrative [Text Block]	rr_ExpenseNarrativeTextBlock	This table describes the fees and expenses that you may pay if you buy and hold Shares of the Fund. Each share class has different expenses, but represents an investment in the same Fund.
Shareholder Fees Caption [Text]	rr_ShareholderFeesCaption	SHAREHOLDER FEES (fees paid directly from your investment)
Operating Expenses Caption [Text]	rr_OperatingExpensesCaption	ANNUAL FUND OPERATING EXPENSES (expenses that you pay each year as a percentage of the value of your investment)
Fee Waiver or Reimbursement over Assets, Date of Termination	rr_FeeWaiverOrReimbursementOverAssetsDateOfTermination	November 1, 2014
Portfolio Turnover [Heading]	rr_PortfolioTurnoverHeading	Portfolio Turnover:
Portfolio Turnover [Text Block]	rr_PortfolioTurnoverTextBlock	The Fund pays transaction costs, such as commissions, when it buys and sells securities (or “turns over” its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when Fund shares are held in a taxable account. These costs, which are not reflected in annual fund operating expenses or in the Example, affect the Fund’s performance. During the most recent fiscal year, the Fund’s portfolio turnover rate was 100% of the average value of its portfolio.
Portfolio Turnover, Rate	rr_PortfolioTurnoverRate	100.00%
Expense Breakpoint Discounts [Text]	rr_ExpenseBreakpointDiscounts	For Class A Shares, you may qualify for sales charge discounts if you and your family invest, or agree to invest in the future, at least $50,000 in the Fund or in other Janus mutual funds. More information about these and other discounts, as well as eligibility requirements for each share class, is available from your financial professional and in the “Purchases” section on page 64 of the Fund’s Prospectus and in the “Purchases” section on page 70 of the Fund’s Statement of Additional Information.
Expense Breakpoint, Minimum Investment Required [Amount]	rr_ExpenseBreakpointMinimumInvestmentRequiredAmount	$ 50,000
Expense Example [Heading]	rr_ExpenseExampleHeading	EXAMPLE:
Expense Example by Year [Heading]	rr_ExpenseExampleByYearHeading	The Example assumes that you invest $10,000 in the Fund for the time periods indicated and reinvest all dividends and distributions. The Example also assumes that your investment has a 5% return each year and that the Fund’s operating expenses without waivers remain the same. Although your actual costs may be higher or lower, based on these assumptions your costs would be:
Expense Example Narrative [Text Block]	rr_ExpenseExampleNarrativeTextBlock	The following Example is based on expenses without waivers. The Example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds.
Expense Example by, Year, Caption [Text]	rr_ExpenseExampleByYearCaption	If Shares are redeemed:
Expense Example, No Redemption, By Year, Caption [Text]	rr_ExpenseExampleNoRedemptionByYearCaption	If Shares are not redeemed:
Strategy [Heading]	rr_StrategyHeading	PRINCIPAL INVESTMENT STRATEGIES
Strategy Narrative [Text Block]	rr_StrategyNarrativeTextBlock	The Fund invests, under normal circumstances, at least 80% of its net assets in short- and intermediate-term securities such as corporate bonds or notes or government securities, including agency securities. The Fund may invest up to 35% of its net assets in high-yield/high-risk bonds, also known as “junk” bonds. The Fund expects to maintain an average-weighted effective maturity of three years or less under normal circumstances. As of June 30, 2013, the Fund’s weighted average maturity was 2.5 years. The Fund may also invest in bank loans, mortgage-backed securities, asset-backed securities, and foreign debt securities (which may include investments in emerging markets). Due to the nature of securities in which the Fund invests, it may have relatively high portfolio turnover compared to other funds. “Effective” maturity differs from actual maturity, which may be longer. In calculating the “effective” maturity the portfolio managers will estimate the effect of expected principal payments and call provisions on securities held in the portfolio. This gives the portfolio managers some additional flexibility in the securities they purchase, but all else being equal, could result in more volatility than if the Fund calculated an actual maturity target. In addition, the Fund may invest its assets in derivatives, which are instruments that have a value derived from, or directly linked to, an underlying asset, such as equity securities, fixed-income securities, commodities, currencies, interest rates, or market indices. In particular, the Fund may use derivatives to manage portfolio risk or to manage the effective maturity of the securities in the Fund’s portfolio. The Fund’s exposure to derivatives will vary. For purposes of meeting its 80% investment policy, the Fund may include derivatives that have characteristics similar to the securities in which the Fund may directly invest. In addition to considering economic factors such as the effect of interest rates on the Fund’s investments, the portfolio managers apply a “bottom up” approach in choosing investments. This means that the portfolio managers look at income-producing securities one at a time to determine if a security is an attractive investment opportunity and if it is consistent with the Fund’s investment policies. The Fund may lend portfolio securities on a short-term or long-term basis, in an amount equal to up to 1/3 of its total assets as determined at the time of the loan origination.
Risk [Heading]	rr_RiskHeading	PRINCIPAL INVESTMENT RISKS
Risk Narrative [Text Block]	rr_RiskNarrativeTextBlock	Although the Fund may be less volatile than funds that invest most of their assets in common stocks, the Fund’s returns and yields will vary, and you could lose money. Fixed-Income Securities Risk. The Fund invests in a variety of fixed-income securities. Typically, the values of fixed-income securities change inversely with prevailing interest rates. Therefore, a fundamental risk of fixed-income securities is interest rate risk, which is the risk that the value of such securities will generally decline as prevailing interest rates rise, which may cause the Fund’s net asset value to likewise decrease. How specific fixed-income securities may react to changes in interest rates will depend on the specific characteristics of each security. Fixed-income securities are also subject to credit risk, prepayment risk, valuation risk, and liquidity risk. Credit risk is the risk that the credit strength of an issuer of a fixed-income security will weaken and/or that the issuer will be unable to make timely principal and interest payments and that the security may go into default. Prepayment risk is the risk that during periods of falling interest rates, certain fixed-income securities with higher interest rates, such as mortgage- and asset-backed securities, may be prepaid by their issuers thereby reducing the amount of interest payments. Valuation risk is the risk that one or more of the fixed-income securities in which the Fund invests are priced differently than the value realized upon such security’s sale. In times of market instability, valuation may be more difficult. Liquidity risk is the risk that fixed-income securities may be difficult or impossible to sell at the time that the portfolio managers would like or at the price the portfolio managers believe the security is currently worth. Sovereign Debt Risk. The Fund may invest in U.S. and foreign government debt securities (“sovereign debt”). Investments in U.S. sovereign debt are considered low risk. However, investments in non-U.S. sovereign debt can involve a high degree of risk, including the risk that the governmental entity that controls the repayment of sovereign debt may not be willing or able to repay the principal and/or to pay the interest on its sovereign debt in a timely manner. A sovereign debtor’s willingness or ability to satisfy its debt obligation may be affected by various factors including, but not limited to, its cash flow situation, the extent of its foreign currency reserves, the availability of foreign exchange when a payment is due, and the relative size of its debt position in relation to its economy as a whole. In the event of default, there may be limited or no legal remedies for collecting sovereign debt and there may be no bankruptcy proceedings through which the Fund may collect all or part of the sovereign debt that a governmental entity has not repaid. Foreign Exposure Risk. The Fund may have exposure to foreign markets as a result of its investments in foreign securities, including investments in emerging markets, which can be more volatile than the U.S. markets. As a result, its returns and net asset value may be affected to a large degree by fluctuations in currency exchange rates or political or economic conditions in a particular country. In some foreign markets, there may not be protection against failure by other parties to complete transactions. It may not be possible for the Fund to repatriate capital, dividends, interest, and other income from a particular country or governmental entity. In addition, a market swing in one or more countries or regions where the Fund has invested a significant amount of its assets may have a greater effect on the Fund’s performance than it would in a more geographically diversified portfolio. To the extent the Fund invests in foreign debt securities, such investments are sensitive to changes in interest rates. Additionally, investments in securities of foreign governments involve the risk that a foreign government may not be willing or able to pay interest or repay principal when due. The Fund’s investments in emerging market countries may involve risks greater than, or in addition to, the risks of investing in more developed countries. Eurozone Risk. A number of countries in the European Union (“EU”) have experienced severe economic and financial difficulties. As a result, financial markets in the EU have been subject to extreme volatility and declines in asset values and liquidity. Responses to these financial problems by European governments, central banks, and others, including austerity measures and reforms, may not work, may result in social unrest, and may limit future growth and economic recovery or have other unintended consequences. Further defaults or restructurings by governments and others of their debt could have additional adverse effects on economies, financial markets, and asset valuations around the world. To the extent that the Fund has exposure to European markets or to transactions tied to the value of the euro, these events could negatively affect the value and liquidity of the Fund’s investments. Mortgage-Backed Securities Risk. Mortgage-backed securities are classified generally as either commercial mortgage-backed securities or residential mortgage-backed securities, each of which is subject to certain specific risks. Mortgage-backed securities tend to be more sensitive to changes in interest rates than other types of debt securities. Investments in mortgage-backed securities are subject to both extension risk, where borrowers extend the duration of their mortgages in times of rising interest rates, and prepayment risk, where borrowers pay off their mortgages sooner than expected in times of declining interest rates. These risks may reduce the Fund’s returns. In addition, investments in mortgage-backed securities, including those comprised of subprime mortgages, may be subject to a higher degree of credit risk, valuation risk, and liquidity risk than various other types of fixed-income securities. Bank Loan Risk. Bank loans are obligations of companies or other entities entered into in connection with recapitalizations, acquisitions, and refinancings. The Fund’s investments in bank loans are generally acquired as a participation interest in, or assignment of, loans originated by a lender or other financial institution. These investments may include institutionally-traded floating and fixed-rate debt securities. Participation interests and assignments involve credit, interest rate, and liquidity risk. In addition, the bank loans underlying these securities often involve borrowers with low credit ratings whose financial conditions are troubled or uncertain, including companies that are highly leveraged or in bankruptcy proceedings. High-Yield/High-Risk Bond Risk. High-yield/high-risk bonds may be more sensitive than other types of bonds to economic changes, political changes, or adverse developments specific to the company that issued the bond, which may adversely affect their value. Portfolio Turnover Risk. Increased portfolio turnover may result in higher costs, which may have a negative effect on the Fund’s performance. In addition, higher portfolio turnover may result in the acceleration of capital gains and the recognition of greater levels of short-term capital gains, which are taxed at ordinary federal income tax rates when distributed to shareholders. Derivatives Risk. Derivatives can be highly volatile and involve risks in addition to the risks of the underlying referenced securities. Gains or losses from a derivative investment can be substantially greater than the derivative’s original cost, and can therefore involve leverage. Leverage may cause the Fund to be more volatile than if it had not used leverage. Derivatives can be less liquid than other types of investments and entail the risk that the counterparty will default on its payment obligations. Securities Lending Risk. The Fund may seek to earn additional income through lending its securities to certain qualified broker-dealers and institutions. There is the risk that when portfolio securities are lent, the securities may not be returned on a timely basis, and the Fund may experience delays and costs in recovering the security or gaining access to the collateral provided to the Fund to collateralize the loan. If the Fund is unable to recover a security on loan, the Fund may use the collateral to purchase replacement securities in the market. There is a risk that the value of the collateral could decrease below the cost of the replacement security by the time the replacement investment is made, resulting in a loss to the Fund. An investment in the Fund is not a bank deposit and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency.
Risk Lose Money [Text]	rr_RiskLoseMoney	Although the Fund may be less volatile than funds that invest most of their assets in common stocks, the Fund’s returns and yields will vary, and you could lose money.
Risk Not Insured Depository Institution [Text]	rr_RiskNotInsuredDepositoryInstitution	An investment in the Fund is not a bank deposit and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency.
Bar Chart and Performance Table [Heading]	rr_BarChartAndPerformanceTableHeading	PERFORMANCE INFORMATION
Performance Narrative [Text Block]	rr_PerformanceNarrativeTextBlock	The following information provides some indication of the risks of investing in the Fund by showing how the Fund’s performance has varied over time. Class T Shares (formerly named Class J Shares, the initial share class) of the Fund commenced operations with the Fund’s inception. Class A Shares, Class C Shares, Class S Shares, and Class I Shares of the Fund commenced operations on July 6, 2009. Class N Shares of the Fund commenced operations on May 31, 2012. The performance shown for Class T Shares is calculated using the fees and expenses of Class T Shares in effect during the periods shown, net of any applicable fee and expense limitations or waivers. The performance shown for Class A Shares, Class C Shares, Class S Shares, and Class I Shares for periods prior to July 6, 2009, reflects the performance of the Fund’s former Class J Shares, calculated using the fees and expenses of each respective share class, without the effect of any fee and expense limitations or waivers. The performance shown for Class N Shares for periods prior to May 31, 2012, reflects the performance of the Fund’s Class T Shares, calculated using the fees and expenses of Class T Shares, net of any applicable fee and expense limitations or waivers. If Class A Shares, Class C Shares, Class S Shares, and Class I Shares of the Fund had been available during periods prior to July 6, 2009, or Class N Shares of the Fund had been available during periods prior to May 31, 2012, the performance shown for each respective share class may have been different. The performance shown for periods following the Fund’s commencement of Class A Shares, Class C Shares, Class S Shares, Class I Shares, and Class N Shares reflects the fees and expenses of each respective share class, net of any applicable fee and expense limitations or waivers. The bar chart depicts the change in performance from year to year during the periods indicated. The bar chart figures do not include any applicable sales charges that an investor may pay when they buy or sell Class A Shares or Class C Shares of the Fund. If sales charges were included, the returns would be lower. The table compares the Fund’s average annual returns for the periods indicated to a broad-based securities market index. The index is not actively managed and is not available for direct investment. All figures assume reinvestment of dividends and distributions. For certain periods, the Fund’s performance reflects the effect of expense waivers. Without the effect of these expense waivers, the performance shown would have been lower. The Fund’s past performance (before and after taxes) does not necessarily indicate how it will perform in the future. Updated performance information is available at janus.com/advisor/mutual-funds or by calling 1-877-335-2687.
Performance Information Illustrates Variability of Returns [Text]	rr_PerformanceInformationIllustratesVariabilityOfReturns	The following information provides some indication of the risks of investing in the Fund by showing how the Fund’s performance has varied over time. The bar chart depicts the change in performance from year to year during the periods indicated.
Performance Additional Market Index [Text]	rr_PerformanceAdditionalMarketIndex	The table compares the Fund’s average annual returns for the periods indicated to a broad-based securities market index. The index is not actively managed and is not available for direct investment. All figures assume reinvestment of dividends and distributions.
Performance Availability Phone [Text]	rr_PerformanceAvailabilityPhone	1-877-335-2687
Performance Availability Website Address [Text]	rr_PerformanceAvailabilityWebSiteAddress	janus.com/advisor/mutual-funds
Performance Past Does Not Indicate Future [Text]	rr_PerformancePastDoesNotIndicateFuture	The Fund’s past performance (before and after taxes) does not necessarily indicate how it will perform in the future.
Bar Chart [Heading]	rr_BarChartHeading	Annual Total Returns for Class T Shares (calendar year-end)
Bar Chart Does Not Reflect Sales Loads [Text]	rr_BarChartDoesNotReflectSalesLoads	The bar chart figures do not include any applicable sales charges that an investor may pay when they buy or sell Class A Shares or Class C Shares of the Fund. If sales charges were included, the returns would be lower.
Bar Chart Closing [Text Block]	rr_BarChartClosingTextBlock	Best Quarter:  Second Quarter 2009  3.18%          Worst Quarter:  Second Quarter 2008  −0.90%
Year to Date Return, Label	rr_YearToDateReturnLabel	The Fund’s year-to-date return as of the calendar quarter ended September 30, 2013 was 0.71%.
Performance Table Heading	rr_PerformanceTableHeading	Average Annual Total Returns (periods ended 12/31/12)
Performance Table Uses Highest Federal Rate	rr_PerformanceTableUsesHighestFederalRate	After-tax returns are calculated using the historically highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes.
Performance Table Not Relevant to Tax Deferred	rr_PerformanceTableNotRelevantToTaxDeferred	Actual after-tax returns depend on your individual tax situation and may differ from those shown in the preceding table. The after-tax return information shown above does not apply to Fund shares held through a tax-deferred account, such as a 401(k) plan or an IRA.
Performance Table One Class of after Tax Shown [Text]	rr_PerformanceTableOneClassOfAfterTaxShown	After-tax returns are only shown for Class T Shares of the Fund. After-tax returns for the other classes of Shares will vary from those shown for Class T Shares due to varying sales charges (as applicable), fees, and expenses among the classes.
Performance Table Narrative	rr_PerformanceTableNarrativeTextBlock	After-tax returns are calculated using distributions for the Fund’s Class T Shares (formerly named Class J Shares, the initial share class). After-tax returns are calculated using the historically highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes. Actual after-tax returns depend on your individual tax situation and may differ from those shown in the preceding table. The after-tax return information shown above does not apply to Fund shares held through a tax-deferred account, such as a 401(k) plan or an IRA. After-tax returns are only shown for Class T Shares of the Fund. After-tax returns for the other classes of Shares will vary from those shown for Class T Shares due to varying sales charges (as applicable), fees, and expenses among the classes.
Performance Table Closing [Text Block]	rr_PerformanceTableClosingTextBlock	Updated performance information is available at janus.com/advisor/mutual-funds or by calling 1-877-335-2687.
Janus Short-Term Bond Fund | Class A, C, S, I, N, T Shares | Class A
Risk/Return:	rr_RiskReturnAbstract
Shareholder Fees Column [Text]	rr_ShareholderFeesColumnName	Class A
Maximum Sales Charge (load) Imposed on Purchases (as a percentage of offering price)	rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice	2.50%
Maximum Deferred Sales Charge (load) (as a percentage of the lower of original purchase price or redemption proceeds)	rr_MaximumDeferredSalesChargeOverOther	none
Operating Expenses Column [Text]	rr_OperatingExpensesColumnName	Class A
Management Fees	rr_ManagementFeesOverAssets	0.55%
Distribution/Service (12b-1) Fees	rr_DistributionAndService12b1FeesOverAssets	0.25%
Other Expenses	rr_OtherExpensesOverAssets	0.15%
Total Annual Fund Operating Expenses	rr_ExpensesOverAssets	0.95%	[1]
Fee Waiver	rr_FeeWaiverOrReimbursementOverAssets	0.15%	[1]
Total Annual Fund Operating Expenses After Fee Waiver	rr_NetExpensesOverAssets	0.80%	[1]
Expense Example, By Year, Column [Text]	rr_ExpenseExampleByYearColumnName	Class A Shares
1 Year	rr_ExpenseExampleYear01	345
3 Years	rr_ExpenseExampleYear03	545
5 Years	rr_ExpenseExampleYear05	762
10 Years	rr_ExpenseExampleYear10	1,387
Expense Example, No Redemption, By Year, Column [Text]	rr_ExpenseExampleNoRedemptionByYearColumnName	Class A Shares
1 Year	rr_ExpenseExampleNoRedemptionYear01	345
3 Years	rr_ExpenseExampleNoRedemptionYear03	545
5 Years	rr_ExpenseExampleNoRedemptionYear05	762
10 Years	rr_ExpenseExampleNoRedemptionYear10	1,387
Janus Short-Term Bond Fund | Class A, C, S, I, N, T Shares | Class C
Risk/Return:	rr_RiskReturnAbstract
Shareholder Fees Column [Text]	rr_ShareholderFeesColumnName	Class C
Maximum Sales Charge (load) Imposed on Purchases (as a percentage of offering price)	rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice	none
Maximum Deferred Sales Charge (load) (as a percentage of the lower of original purchase price or redemption proceeds)	rr_MaximumDeferredSalesChargeOverOther	1.00%
Operating Expenses Column [Text]	rr_OperatingExpensesColumnName	Class C
Management Fees	rr_ManagementFeesOverAssets	0.55%
Distribution/Service (12b-1) Fees	rr_DistributionAndService12b1FeesOverAssets	1.00%
Other Expenses	rr_OtherExpensesOverAssets	0.14%
Total Annual Fund Operating Expenses	rr_ExpensesOverAssets	1.69%	[1]
Fee Waiver	rr_FeeWaiverOrReimbursementOverAssets	0.14%	[1]
Total Annual Fund Operating Expenses After Fee Waiver	rr_NetExpensesOverAssets	1.55%	[1]
Expense Example, By Year, Column [Text]	rr_ExpenseExampleByYearColumnName	Class C Shares
1 Year	rr_ExpenseExampleYear01	272
3 Years	rr_ExpenseExampleYear03	533
5 Years	rr_ExpenseExampleYear05	918
10 Years	rr_ExpenseExampleYear10	1,998
Expense Example, No Redemption, By Year, Column [Text]	rr_ExpenseExampleNoRedemptionByYearColumnName	Class C Shares
1 Year	rr_ExpenseExampleNoRedemptionYear01	172
3 Years	rr_ExpenseExampleNoRedemptionYear03	533
5 Years	rr_ExpenseExampleNoRedemptionYear05	918
10 Years	rr_ExpenseExampleNoRedemptionYear10	1,998
Janus Short-Term Bond Fund | Class A, C, S, I, N, T Shares | Class S
Risk/Return:	rr_RiskReturnAbstract
Shareholder Fees Column [Text]	rr_ShareholderFeesColumnName	Class S
Maximum Sales Charge (load) Imposed on Purchases (as a percentage of offering price)	rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice	none
Maximum Deferred Sales Charge (load) (as a percentage of the lower of original purchase price or redemption proceeds)	rr_MaximumDeferredSalesChargeOverOther	none
Operating Expenses Column [Text]	rr_OperatingExpensesColumnName	Class S
Management Fees	rr_ManagementFeesOverAssets	0.55%
Distribution/Service (12b-1) Fees	rr_DistributionAndService12b1FeesOverAssets	0.25%
Other Expenses	rr_OtherExpensesOverAssets	0.30%
Total Annual Fund Operating Expenses	rr_ExpensesOverAssets	1.10%	[1]
Fee Waiver	rr_FeeWaiverOrReimbursementOverAssets	0.11%	[1]
Total Annual Fund Operating Expenses After Fee Waiver	rr_NetExpensesOverAssets	0.99%	[1]
Expense Example, By Year, Column [Text]	rr_ExpenseExampleByYearColumnName	Class S Shares
1 Year	rr_ExpenseExampleYear01	112
3 Years	rr_ExpenseExampleYear03	350
5 Years	rr_ExpenseExampleYear05	606
10 Years	rr_ExpenseExampleYear10	1,340
Expense Example, No Redemption, By Year, Column [Text]	rr_ExpenseExampleNoRedemptionByYearColumnName	Class S Shares
1 Year	rr_ExpenseExampleNoRedemptionYear01	112
3 Years	rr_ExpenseExampleNoRedemptionYear03	350
5 Years	rr_ExpenseExampleNoRedemptionYear05	606
10 Years	rr_ExpenseExampleNoRedemptionYear10	1,340
Janus Short-Term Bond Fund | Class A, C, S, I, N, T Shares | Class I
Risk/Return:	rr_RiskReturnAbstract
Shareholder Fees Column [Text]	rr_ShareholderFeesColumnName	Class I
Maximum Sales Charge (load) Imposed on Purchases (as a percentage of offering price)	rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice	none
Maximum Deferred Sales Charge (load) (as a percentage of the lower of original purchase price or redemption proceeds)	rr_MaximumDeferredSalesChargeOverOther	none
Operating Expenses Column [Text]	rr_OperatingExpensesColumnName	Class I
Management Fees	rr_ManagementFeesOverAssets	0.55%
Distribution/Service (12b-1) Fees	rr_DistributionAndService12b1FeesOverAssets	none
Other Expenses	rr_OtherExpensesOverAssets	0.11%
Total Annual Fund Operating Expenses	rr_ExpensesOverAssets	0.66%	[1]
Fee Waiver	rr_FeeWaiverOrReimbursementOverAssets	0.12%	[1]
Total Annual Fund Operating Expenses After Fee Waiver	rr_NetExpensesOverAssets	0.54%	[1]
Expense Example, By Year, Column [Text]	rr_ExpenseExampleByYearColumnName	Class I Shares
1 Year	rr_ExpenseExampleYear01	67
3 Years	rr_ExpenseExampleYear03	211
5 Years	rr_ExpenseExampleYear05	368
10 Years	rr_ExpenseExampleYear10	822
Expense Example, No Redemption, By Year, Column [Text]	rr_ExpenseExampleNoRedemptionByYearColumnName	Class I Shares
1 Year	rr_ExpenseExampleNoRedemptionYear01	67
3 Years	rr_ExpenseExampleNoRedemptionYear03	211
5 Years	rr_ExpenseExampleNoRedemptionYear05	368
10 Years	rr_ExpenseExampleNoRedemptionYear10	822
Janus Short-Term Bond Fund | Class A, C, S, I, N, T Shares | Class N
Risk/Return:	rr_RiskReturnAbstract
Shareholder Fees Column [Text]	rr_ShareholderFeesColumnName	Class N
Maximum Sales Charge (load) Imposed on Purchases (as a percentage of offering price)	rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice	none
Maximum Deferred Sales Charge (load) (as a percentage of the lower of original purchase price or redemption proceeds)	rr_MaximumDeferredSalesChargeOverOther	none
Operating Expenses Column [Text]	rr_OperatingExpensesColumnName	Class N
Management Fees	rr_ManagementFeesOverAssets	0.55%
Distribution/Service (12b-1) Fees	rr_DistributionAndService12b1FeesOverAssets	none
Other Expenses	rr_OtherExpensesOverAssets	0.05%
Total Annual Fund Operating Expenses	rr_ExpensesOverAssets	0.60%	[1]
Fee Waiver	rr_FeeWaiverOrReimbursementOverAssets	0.11%	[1]
Total Annual Fund Operating Expenses After Fee Waiver	rr_NetExpensesOverAssets	0.49%	[1]
Expense Example, By Year, Column [Text]	rr_ExpenseExampleByYearColumnName	Class N Shares
1 Year	rr_ExpenseExampleYear01	61
3 Years	rr_ExpenseExampleYear03	192
5 Years	rr_ExpenseExampleYear05	335
10 Years	rr_ExpenseExampleYear10	750
Expense Example, No Redemption, By Year, Column [Text]	rr_ExpenseExampleNoRedemptionByYearColumnName	Class N Shares
1 Year	rr_ExpenseExampleNoRedemptionYear01	61
3 Years	rr_ExpenseExampleNoRedemptionYear03	192
5 Years	rr_ExpenseExampleNoRedemptionYear05	335
10 Years	rr_ExpenseExampleNoRedemptionYear10	750
Janus Short-Term Bond Fund | Class A, C, S, I, N, T Shares | Class T
Risk/Return:	rr_RiskReturnAbstract
Shareholder Fees Column [Text]	rr_ShareholderFeesColumnName	Class T
Maximum Sales Charge (load) Imposed on Purchases (as a percentage of offering price)	rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice	none
Maximum Deferred Sales Charge (load) (as a percentage of the lower of original purchase price or redemption proceeds)	rr_MaximumDeferredSalesChargeOverOther	none
Operating Expenses Column [Text]	rr_OperatingExpensesColumnName	Class T
Management Fees	rr_ManagementFeesOverAssets	0.55%
Distribution/Service (12b-1) Fees	rr_DistributionAndService12b1FeesOverAssets	none
Other Expenses	rr_OtherExpensesOverAssets	0.30%
Total Annual Fund Operating Expenses	rr_ExpensesOverAssets	0.85%	[1]
Fee Waiver	rr_FeeWaiverOrReimbursementOverAssets	0.11%	[1]
Total Annual Fund Operating Expenses After Fee Waiver	rr_NetExpensesOverAssets	0.74%	[1]
Expense Example, By Year, Column [Text]	rr_ExpenseExampleByYearColumnName	Class T Shares
1 Year	rr_ExpenseExampleYear01	87
3 Years	rr_ExpenseExampleYear03	271
5 Years	rr_ExpenseExampleYear05	471
10 Years	rr_ExpenseExampleYear10	1,049
Expense Example, No Redemption, By Year, Column [Text]	rr_ExpenseExampleNoRedemptionByYearColumnName	Class T Shares
1 Year	rr_ExpenseExampleNoRedemptionYear01	87
3 Years	rr_ExpenseExampleNoRedemptionYear03	271
5 Years	rr_ExpenseExampleNoRedemptionYear05	471
10 Years	rr_ExpenseExampleNoRedemptionYear10	$ 1,049
2003	rr_AnnualReturn2003	3.91%
2004	rr_AnnualReturn2004	1.96%
2005	rr_AnnualReturn2005	1.52%
2006	rr_AnnualReturn2006	4.21%
2007	rr_AnnualReturn2007	5.21%
2008	rr_AnnualReturn2008	4.63%
2009	rr_AnnualReturn2009	8.56%
2010	rr_AnnualReturn2010	3.37%
2011	rr_AnnualReturn2011	1.37%
2012	rr_AnnualReturn2012	3.42%
Bar Chart, Year to Date Return, Date	rr_BarChartYearToDateReturnDate	Sep. 30, 2013
Bar Chart, Year to Date Return	rr_BarChartYearToDateReturn	0.71%
Highest Quarterly Return, Label	rr_HighestQuarterlyReturnLabel	Best Quarter:
Highest Quarterly Return, Date	rr_BarChartHighestQuarterlyReturnDate	Jun. 30, 2009
Highest Quarterly Return	rr_BarChartHighestQuarterlyReturn	3.18%
Lowest Quarterly Return, Label	rr_LowestQuarterlyReturnLabel	Worst Quarter:
Lowest Quarterly Return, Date	rr_BarChartLowestQuarterlyReturnDate	Jun. 30, 2008
Lowest Quarterly Return	rr_BarChartLowestQuarterlyReturn	(0.90%)
Janus Short-Term Bond Fund | Class A, C, S, I, N, T Shares | Return Before Taxes | Class A
Risk/Return:	rr_RiskReturnAbstract
Column	rr_AverageAnnualReturnColumnName	Class A Shares
Label	rr_AverageAnnualReturnLabel	Return Before Taxes	[2]
1 Year	rr_AverageAnnualReturnYear01	0.78%
5 Years	rr_AverageAnnualReturnYear05	3.15%
10 Years	rr_AverageAnnualReturnYear10	3.01%
Since Inception	rr_AverageAnnualReturnSinceInception	3.96%
Inception Date	rr_AverageAnnualReturnInceptionDate	Sep. 01, 1992
Janus Short-Term Bond Fund | Class A, C, S, I, N, T Shares | Return Before Taxes | Class C
Risk/Return:	rr_RiskReturnAbstract
Column	rr_AverageAnnualReturnColumnName	Class C Shares
Label	rr_AverageAnnualReturnLabel	Return Before Taxes	[3]
1 Year	rr_AverageAnnualReturnYear01	1.67%
5 Years	rr_AverageAnnualReturnYear05	3.54%
10 Years	rr_AverageAnnualReturnYear10	2.89%
Since Inception	rr_AverageAnnualReturnSinceInception	3.53%
Inception Date	rr_AverageAnnualReturnInceptionDate	Sep. 01, 1992
Janus Short-Term Bond Fund | Class A, C, S, I, N, T Shares | Return Before Taxes | Class S
Risk/Return:	rr_RiskReturnAbstract
Column	rr_AverageAnnualReturnColumnName	Class S Shares
Label	rr_AverageAnnualReturnLabel	Return Before Taxes
1 Year	rr_AverageAnnualReturnYear01	3.23%
5 Years	rr_AverageAnnualReturnYear05	3.81%
10 Years	rr_AverageAnnualReturnYear10	3.27%
Since Inception	rr_AverageAnnualReturnSinceInception	4.01%
Inception Date	rr_AverageAnnualReturnInceptionDate	Sep. 01, 1992
Janus Short-Term Bond Fund | Class A, C, S, I, N, T Shares | Return Before Taxes | Class I
Risk/Return:	rr_RiskReturnAbstract
Column	rr_AverageAnnualReturnColumnName	Class I Shares
Label	rr_AverageAnnualReturnLabel	Return Before Taxes
1 Year	rr_AverageAnnualReturnYear01	3.68%
5 Years	rr_AverageAnnualReturnYear05	4.24%
10 Years	rr_AverageAnnualReturnYear10	3.72%
Since Inception	rr_AverageAnnualReturnSinceInception	4.43%
Inception Date	rr_AverageAnnualReturnInceptionDate	Sep. 01, 1992
Janus Short-Term Bond Fund | Class A, C, S, I, N, T Shares | Return Before Taxes | Class N
Risk/Return:	rr_RiskReturnAbstract
Column	rr_AverageAnnualReturnColumnName	Class N Shares
Label	rr_AverageAnnualReturnLabel	Return Before Taxes
1 Year	rr_AverageAnnualReturnYear01	3.42%
5 Years	rr_AverageAnnualReturnYear05	4.24%
10 Years	rr_AverageAnnualReturnYear10	3.80%
Since Inception	rr_AverageAnnualReturnSinceInception	4.58%
Inception Date	rr_AverageAnnualReturnInceptionDate	Sep. 01, 1992
Janus Short-Term Bond Fund | Class A, C, S, I, N, T Shares | Return Before Taxes | Class T
Risk/Return:	rr_RiskReturnAbstract
Column	rr_AverageAnnualReturnColumnName	Class T Shares
Label	rr_AverageAnnualReturnLabel	Return Before Taxes
1 Year	rr_AverageAnnualReturnYear01	3.42%
5 Years	rr_AverageAnnualReturnYear05	4.24%
10 Years	rr_AverageAnnualReturnYear10	3.80%
Since Inception	rr_AverageAnnualReturnSinceInception	4.58%
Inception Date	rr_AverageAnnualReturnInceptionDate	Sep. 01, 1992
Janus Short-Term Bond Fund | Class A, C, S, I, N, T Shares | Return After Taxes on Distributions | Class T
Risk/Return:	rr_RiskReturnAbstract
Column	rr_AverageAnnualReturnColumnName	Class T Shares
Label	rr_AverageAnnualReturnLabel	Return After Taxes on Distributions
1 Year	rr_AverageAnnualReturnYear01	2.65%
5 Years	rr_AverageAnnualReturnYear05	3.23%
10 Years	rr_AverageAnnualReturnYear10	2.67%
Since Inception	rr_AverageAnnualReturnSinceInception	2.90%
Inception Date	rr_AverageAnnualReturnInceptionDate	Sep. 01, 1992
Janus Short-Term Bond Fund | Class A, C, S, I, N, T Shares | Return After Taxes on Distributions and Sale of Fund Shares | Class T
Risk/Return:	rr_RiskReturnAbstract
Column	rr_AverageAnnualReturnColumnName	Class T Shares
Label	rr_AverageAnnualReturnLabel	Return After Taxes on Distributions and Sale of Fund Shares
1 Year	rr_AverageAnnualReturnYear01	2.31%
5 Years	rr_AverageAnnualReturnYear05	3.06%
10 Years	rr_AverageAnnualReturnYear10	2.60%
Since Inception	rr_AverageAnnualReturnSinceInception	2.88%
Inception Date	rr_AverageAnnualReturnInceptionDate	Sep. 01, 1992
Janus Short-Term Bond Fund | Class A, C, S, I, N, T Shares | Barclays 1-3 Year U.S. Government/Credit Index (reflects no deduction for expenses, fees, or taxes)
Risk/Return:	rr_RiskReturnAbstract
Label	rr_AverageAnnualReturnLabel	Barclays 1-3 Year U.S. Government/Credit Index
1 Year	rr_AverageAnnualReturnYear01	1.26%
5 Years	rr_AverageAnnualReturnYear05	2.88%
10 Years	rr_AverageAnnualReturnYear10	3.13%
Since Inception	rr_AverageAnnualReturnSinceInception	4.62%
Inception Date	rr_AverageAnnualReturnInceptionDate	Sep. 01, 1992

[1] Janus Capital has contractually agreed to waive its investment advisory fee and/or reimburse Fund expenses to the extent that the Fund’s total annual fund operating expenses (excluding the distribution and shareholder servicing fees – applicable to Class A Shares, Class C Shares, and Class S Shares; administrative services fees payable pursuant to the Transfer Agency Agreement; brokerage commissions; interest; dividends; taxes; acquired fund fees and expenses; and extraordinary expenses) exceed 0.49% until at least November 1, 2014. The contractual waiver may be terminated or modified prior to this date only at the discretion of the Board of Trustees.

[2] Calculated assuming maximum permitted sales loads.

[3] The one year return is calculated to include the contingent deferred sales charge.

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Janus Flexible Bond Fund | Class D Shares

FUND SUMMARY

Janus Flexible Bond Fund

INVESTMENT OBJECTIVE

Janus Flexible Bond Fund seeks to obtain maximum total return, consistent with preservation of capital.

FEES AND EXPENSES OF THE FUND

This table describes the fees and expenses that you may pay if you buy and hold Shares of the Fund.

ANNUAL FUND OPERATING EXPENSES
(expenses that you pay each year as a percentage of the value of your investment)

Annual Fund Operating Expenses	Janus Flexible Bond Fund Class D Shares Class D
Operating Expenses Column [Text]	Class D
Management Fees	0.40%
Other Expenses	0.20%
Total Annual Fund Operating Expenses	0.60%

EXAMPLE:

The Example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds.

The Example assumes that you invest $10,000 in the Fund for the time periods indicated, reinvest all dividends and distributions, and then redeem all of your Shares at the end of each period. The Example also assumes that your investment has a 5% return each year and that the Fund’s operating expenses remain the same. Although your actual costs may be higher or lower, based on these assumptions your costs would be:

Expense Example (USD $)	Expense Example, By Year, Column [Text]	1 Year	3 Years	5 Years	10 Years
Janus Flexible Bond Fund Class D Shares Class D	Class D Shares	61	192	335	750

Portfolio Turnover:

The Fund pays transaction costs, such as commissions, when it buys and sells securities (or “turns over” its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when Fund shares are held in a taxable account. These costs, which are not reflected in annual fund operating expenses or in the Example, affect the Fund’s performance. During the most recent fiscal year, the Fund’s portfolio turnover rate was 118% of the average value of its portfolio.

PRINCIPAL INVESTMENT STRATEGIES

The Fund pursues its investment objective by primarily investing, under normal circumstances, at least 80% of its net assets in bonds. Bonds include, but are not limited to, government notes and bonds, corporate bonds, convertible bonds, commercial and residential mortgage-backed securities, and zero-coupon bonds. The Fund will invest at least 65% of its assets in investment grade debt securities. As of June 30, 2013, the Fund’s weighted average maturity was 6.9 years. The Fund will limit its investment in high-yield/high-risk bonds, also known as “junk” bonds, to 35% or less of its net assets. The Fund generates total return from a combination of current income and capital appreciation, but income is usually the dominant portion. The Fund may also invest in asset-backed securities, money market instruments, bank loans, and foreign debt securities (which may include investments in emerging markets). Due to the nature of the securities in which the Fund invests, it may have relatively high portfolio turnover compared to other Funds.

In addition, the Fund may invest its assets in derivatives, which are instruments that have a value derived from, or directly linked to, an underlying asset, such as equity securities, fixed-income securities, commodities, currencies, interest rates, or market indices. In particular, the Fund may use interest rate futures to manage portfolio risk. The Fund’s exposure to derivatives will vary. For purposes of meeting its 80% investment policy, the Fund may include derivatives that have characteristics similar to the securities in which the Fund may directly invest.

In addition to considering economic factors such as the effect of interest rates on the Fund’s investments, the portfolio managers apply a “bottom up” approach in choosing investments. This means that the portfolio managers look at income-producing securities one at a time to determine if a security is an attractive investment opportunity and if it is consistent with the Fund’s investment policies.

The Fund may lend portfolio securities on a short-term or long-term basis, in an amount equal to up to 1/3 of its total assets as determined at the time of the loan origination.

PRINCIPAL INVESTMENT RISKS

Although the Fund may be less volatile than funds that invest most of their assets in common stocks, the Fund’s returns and yields will vary, and you could lose money.

Fixed-Income Securities Risk. The Fund invests in a variety of fixed-income securities. Typically, the values of fixed-income securities change inversely with prevailing interest rates. Therefore, a fundamental risk of fixed-income securities is interest rate risk, which is the risk that the value of such securities will generally decline as prevailing interest rates rise, which may cause the Fund’s net asset value to likewise decrease. How specific fixed-income securities may react to changes in interest rates will depend on the specific characteristics of each security. Fixed-income securities are also subject to credit risk, prepayment risk, valuation risk, and liquidity risk. Credit risk is the risk that the credit strength of an issuer of a fixed-income security will weaken and/or that the issuer will be unable to make timely principal and interest payments and that the security may go into default. Prepayment risk is the risk that during periods of falling interest rates, certain fixed-income securities with higher interest rates, such as mortgage- and asset-backed securities, may be prepaid by their issuers thereby reducing the amount of interest payments. Valuation risk is the risk that one or more of the fixed-income securities in which the Fund invests are priced differently than the value realized upon such security’s sale. In times of market instability, valuation may be more difficult. Liquidity risk is the risk that fixed-income securities may be difficult or impossible to sell at the time that the portfolio managers would like or at the price the portfolio managers believe the security is currently worth.

Mortgage-Backed Securities Risk. Mortgage-backed securities are classified generally as either commercial mortgage-backed securities or residential mortgage-backed securities, each of which is subject to certain specific risks. Mortgage-backed securities tend to be more sensitive to changes in interest rates than other types of debt securities. Investments in mortgage-backed securities are subject to both extension risk, where borrowers extend the duration of their mortgages in times of rising interest rates, and prepayment risk, where borrowers pay off their mortgages sooner than expected in times of declining interest rates. These risks may reduce the Fund’s returns. In addition, investments in mortgage-backed securities, including those comprised of subprime mortgages, may be subject to a higher degree of credit risk, valuation risk, and liquidity risk than various other types of fixed-income securities.

Sovereign Debt Risk. The Fund may invest in U.S. and foreign government debt securities (“sovereign debt”). Investments in U.S. sovereign debt are considered low risk. However, investments in non-U.S. sovereign debt can involve a high degree of risk, including the risk that the governmental entity that controls the repayment of sovereign debt may not be willing or able to repay the principal and/or to pay the interest on its sovereign debt in a timely manner. A sovereign debtor’s willingness or ability to satisfy its debt obligation may be affected by various factors including, but not limited to, its cash flow situation, the extent of its foreign currency reserves, the availability of foreign exchange when a payment is due, and the relative size of its debt position in relation to its economy as a whole. In the event of default, there may be limited or no legal remedies for collecting sovereign debt and there may be no bankruptcy proceedings through which the Fund may collect all or part of the sovereign debt that a governmental entity has not repaid.

High-Yield/High-Risk Bond Risk. High-yield/high-risk bonds may be more sensitive than other types of bonds to economic changes, political changes, or adverse developments specific to the company that issued the bond, which may adversely affect their value.

Bank Loan Risk. Bank loans are obligations of companies or other entities entered into in connection with recapitalizations, acquisitions, and refinancings. The Fund’s investments in bank loans are generally acquired as a participation interest in, or assignment of, loans originated by a lender or other financial institution. These investments may include institutionally-traded floating and fixed-rate debt securities. Participation interests and assignments involve credit, interest rate, and liquidity risk. In addition, the bank loans underlying these securities often involve borrowers with low credit ratings whose financial conditions are troubled or uncertain, including companies that are highly leveraged or in bankruptcy proceedings.

Foreign Exposure Risk. The Fund may have exposure to foreign markets as a result of its investments in foreign securities, including investments in emerging markets, which can be more volatile than the U.S. markets. As a result, its returns and net asset value may be affected to a large degree by fluctuations in currency exchange rates or political or economic conditions in a particular country. In some foreign markets, there may not be protection against failure by other parties to complete transactions. It may not be possible for the Fund to repatriate capital, dividends, interest, and other income from a particular country or governmental entity. In addition, a market swing in one or more countries or regions where the Fund has invested a significant amount of its assets may have a greater effect on the Fund’s performance than it would in a more geographically diversified portfolio. To the extent the Fund invests in foreign debt securities, such investments are sensitive to changes in interest rates. Additionally, investments in securities of foreign governments involve the risk that a foreign government may not be willing or able to pay interest or repay principal when due. The Fund’s investments in emerging market countries may involve risks greater than, or in addition to, the risks of investing in more developed countries.

Portfolio Turnover Risk. Increased portfolio turnover may result in higher costs, which may have a negative effect on the Fund’s performance. In addition, higher portfolio turnover may result in the acceleration of capital gains and the recognition of greater levels of short-term capital gains, which are taxed at ordinary federal income tax rates when distributed to shareholders.

Derivatives Risk. Derivatives can be highly volatile and involve risks in addition to the risks of the underlying referenced securities. Gains or losses from a derivative investment can be substantially greater than the derivative’s original cost, and can therefore involve leverage. Leverage may cause the Fund to be more volatile than if it had not used leverage. Derivatives can be less liquid than other types of investments and entail the risk that the counterparty will default on its payment obligations.

Securities Lending Risk. The Fund may seek to earn additional income through lending its securities to certain qualified broker-dealers and institutions. There is the risk that when portfolio securities are lent, the securities may not be returned on a timely basis, and the Fund may experience delays and costs in recovering the security or gaining access to the collateral provided to the Fund to collateralize the loan. If the Fund is unable to recover a security on loan, the Fund may use the collateral to purchase replacement securities in the market. There is a risk that the value of the collateral could decrease below the cost of the replacement security by the time the replacement investment is made, resulting in a loss to the Fund.

An investment in the Fund is not a bank deposit and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency.

PERFORMANCE INFORMATION

The following information provides some indication of the risks of investing in the Fund by showing how the Fund’s performance has varied over time. Class D Shares of the Fund commenced operations on February 16, 2010, as a result of the restructuring of Class J Shares, the predecessor share class. The performance shown for Class D Shares for periods prior to February 16, 2010, reflects the performance of the Fund’s former Class J Shares, calculated using the fees and expenses in effect during the periods shown, net of any applicable fee and expense limitations or waivers. If Class D Shares of the Fund had been available during periods prior to February 16, 2010, the performance shown may have been different. The performance shown for periods following the Fund’s commencement of Class D Shares reflects the fees and expenses of Class D Shares, net of any applicable fee and expense limitations or waivers.

The bar chart depicts the change in performance from year to year during the periods indicated. The table compares the Fund’s average annual returns for the periods indicated to a broad-based securities market index. The index is not actively managed and is not available for direct investment. All figures assume reinvestment of dividends and distributions. For certain periods, the Fund’s performance reflects the effect of expense waivers. Without the effect of these expense waivers, the performance shown would have been lower.

The Fund’s past performance (before and after taxes) does not necessarily indicate how it will perform in the future. Updated performance information is available at janus.com/allfunds or by calling 1-800-525-3713.

Annual Total Returns for Class D Shares (calendar year-end)

Best Quarter:  Third Quarter 2009  5.58%          Worst Quarter:  Second Quarter 2004  −2.99%

The Fund’s year-to-date return as of the calendar quarter ended September 30, 2013 was −0.89%.

Average Annual Total Returns (periods ended 12/31/12)

Average Annual Total Returns Janus Flexible Bond Fund Class D Shares	Column	Label	1 Year	5 Years	10 Years	Since Inception	Inception Date
Class D Return Before Taxes	Class D Shares	Return Before Taxes	8.01%	8.05%	6.30%	7.56%	Jul. 07, 1987
Class D Return After Taxes on Distributions	Class D Shares	Return After Taxes on Distributions	6.30%	6.18%	4.54%	4.98%	Jul. 07, 1987
Class D Return After Taxes on Distributions and Sale of Fund Shares	Class D Shares	Return After Taxes on Distributions and Sale of Fund Shares	5.37%	5.86%	4.38%	4.92%	Jul. 07, 1987
Barclays U.S. Aggregate Bond Index (reflects no deduction for expenses, fees, or taxes)		Barclays U.S. Aggregate Bond Index	4.21%	5.95%	5.18%	7.21%	Jul. 07, 1987

After-tax returns are calculated using distributions for the Fund’s Class D Shares for the periods following February 16, 2010; and for the Fund’s Class J Shares, the predecessor share class, for the periods prior to February 16, 2010. If Class D Shares of the Fund had been available during these earlier periods, distributions may have been different and thus, after-tax returns may have been different from those shown. After-tax returns are calculated using the historically highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes. Actual after-tax returns depend on your individual tax situation and may differ from those shown in the preceding table. The after-tax return information shown above does not apply to Fund shares held through a tax-deferred account, such as a 401(k) plan or an IRA.

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INTECH U.S. Growth Fund | Class A, C, S, I, T Shares

FUND SUMMARY

INTECH U.S. Growth Fund

INVESTMENT OBJECTIVE

INTECH U.S. Growth Fund seeks long-term growth of capital.

FEES AND EXPENSES OF THE FUND

This table describes the fees and expenses that you may pay if you buy and hold Shares of the Fund. Each share class has different expenses, but represents an investment in the same Fund.

For Class A Shares, you may qualify for sales charge discounts if you and your family invest, or agree to invest in the future, at least $50,000 in the Fund or in other Janus mutual funds. More information about these and other discounts, as well as eligibility requirements for each share class, is available from your financial professional and in the “Purchases” section on page 51 of the Fund’s Prospectus and in the “Purchases” section on page 70 of the Fund’s Statement of Additional Information.

SHAREHOLDER FEES
(fees paid directly from your investment)

Shareholder Fees INTECH U.S. Growth Fund Class A, C, S, I, T Shares	Class A	Class C	Class S	Class I	Class T
Shareholder Fees Column [Text]	Class A	Class C	Class S	Class I	Class T
Maximum Sales Charge (load) Imposed on Purchases (as a percentage of offering price)	5.75%	none	none	none	none
Maximum Deferred Sales Charge (load) (as a percentage of the lower of original purchase price or redemption proceeds)	none	1.00%	none	none	none

ANNUAL FUND OPERATING EXPENSES
(expenses that you pay each year as a percentage of the value of your investment)

Annual Fund Operating Expenses INTECH U.S. Growth Fund Class A, C, S, I, T Shares	Class A	Class C	Class S	Class I	Class T
Operating Expenses Column [Text]	Class A	Class C	Class S	Class I	Class T
Management Fees	0.50%	0.50%	0.50%	0.50%	0.50%
Distribution/Service (12b-1) Fees	0.25%	1.00%	0.25%	none	none
Other Expenses	0.15%	0.10%	0.31%	0.08%	0.31%
Total Annual Fund Operating Expenses	0.90%	1.60%	1.06%	0.58%	0.81%

EXAMPLE:

The Example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds.

The Example assumes that you invest $10,000 in the Fund for the time periods indicated and reinvest all dividends and distributions. The Example also assumes that your investment has a 5% return each year and that the Fund’s operating expenses remain the same. Although your actual costs may be higher or lower, based on these assumptions your costs would be:

If Shares are redeemed:

Expense Example INTECH U.S. Growth Fund Class A, C, S, I, T Shares (USD $)	Expense Example, By Year, Column [Text]	1 Year	3 Years	5 Years	10 Years
Class A	Class A Shares	662	845	1,045	1,619
Class C	Class C Shares	263	505	871	1,900
Class S	Class S Shares	108	337	585	1,294
Class I	Class I Shares	59	186	324	726
Class T	Class T Shares	83	259	450	1,002

If Shares are not redeemed:

Expense Example, No Redemption INTECH U.S. Growth Fund Class A, C, S, I, T Shares (USD $)	Expense Example, No Redemption, By Year, Column [Text]	1 Year	3 Years	5 Years	10 Years
Class A	Class A Shares	662	845	1,045	1,619
Class C	Class C Shares	163	505	871	1,900
Class S	Class S Shares	108	337	585	1,294
Class I	Class I Shares	59	186	324	726
Class T	Class T Shares	83	259	450	1,002

Portfolio Turnover: 

The Fund pays transaction costs, such as commissions, when it buys and sells securities (or “turns over” its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when Fund shares are held in a taxable account. These costs, which are not reflected in annual fund operating expenses or in the Example, affect the Fund’s performance. During the most recent fiscal year, the Fund’s portfolio turnover rate was 81% of the average value of its portfolio.

PRINCIPAL INVESTMENT STRATEGIES

The Fund invests, under normal circumstances, at least 80% of its net assets in U.S. common stocks from the universe of the Russell 1000^® Growth Index, utilizing INTECH’s mathematical investment process. The Russell 1000^® Growth Index is an unmanaged index that measures the performance of those Russell 1000 companies with higher price-to-book ratios and higher forecasted growth values.

The Fund pursues its investment objective by applying a mathematical investment process to construct an investment portfolio from the universe of common stocks within its named benchmark index. The goal of this process is to build a portfolio of stocks in a more efficient combination than the named benchmark index. The process seeks to capitalize on the natural volatility of the market by searching for stocks within the index that have high relative volatility (providing the potential for excess returns) but that essentially move in opposite directions or have low correlation to each other (providing the potential for lower relative risk). By constructing the portfolio in this manner and periodically rebalancing the portfolio to maintain potentially more efficient weightings, INTECH’s mathematical investment process seeks to create a portfolio that, over time, produces returns in excess of its named benchmark index with risks similar to that of the benchmark index. The rebalancing techniques used by INTECH may result in a higher portfolio turnover compared to a “buy and hold” fund strategy.

The Fund may lend portfolio securities on a short-term or long-term basis, in an amount equal to up to 1/3 of its total assets as determined at the time of the loan origination.

PRINCIPAL INVESTMENT RISKS

The biggest risk is that the Fund’s returns will vary, and you could lose money. The Fund is designed for long-term investors seeking an equity portfolio, including common stocks. Common stocks tend to be more volatile than many other investment choices.

Growth Securities Risk. Securities of companies perceived to be “growth” companies may be more volatile than other stocks and may involve special risks. If a company’s growth potential is not realized, the securities purchased may not perform as expected, reducing the Fund’s returns. In addition, because different types of stocks tend to shift in and out of favor depending on market and economic conditions, “growth” stocks may perform differently from the market as a whole and other types of securities.

Market Risk. The value of the Fund’s portfolio may decrease if the value of an individual company or security, or multiple companies or securities, in the portfolio decreases. Further, regardless of how well individual companies or securities perform, the value of the Fund’s portfolio could also decrease if there are deteriorating economic or market conditions. It is important to understand that the value of your investment may fall, sometimes sharply, in response to changes in the market, and you could lose money.

Investment Process Risk. The proprietary mathematical investment process used by INTECH may not achieve the desired results. There is a risk that INTECH’s method of identifying stocks with higher volatility than the named benchmark index or its method of identifying stocks that tend to move in the same or opposite direction relative to each other (correlation) will not result in selecting stocks with continuing volatility or the expected correlation. In INTECH’s history, which spans more than 25 years, INTECH’s mathematical investment process has experienced periods of both underperformance and outperformance relative to an identified benchmark. Even when the proprietary mathematical investment process is working appropriately, INTECH expects that there will be periods of underperformance relative to the benchmark. On an occasional basis, INTECH makes changes to its mathematical investment process. These changes may result in changes to the portfolio, might not provide the intended results, and may adversely impact the Fund’s performance.

Portfolio Turnover Risk. Increased portfolio turnover may result in higher costs, which may have a negative effect on the Fund’s performance. In addition, higher portfolio turnover may result in the acceleration of capital gains and the recognition of greater levels of short-term capital gains, which are taxed at ordinary federal income tax rates when distributed to shareholders.

Securities Lending Risk. The Fund may seek to earn additional income through lending its securities to certain qualified broker-dealers and institutions. There is the risk that when portfolio securities are lent, the securities may not be returned on a timely basis, and the Fund may experience delays and costs in recovering the security or gaining access to the collateral provided to the Fund to collateralize the loan. If the Fund is unable to recover a security on loan, the Fund may use the collateral to purchase replacement securities in the market. There is a risk that the value of the collateral could decrease below the cost of the replacement security by the time the replacement investment is made, resulting in a loss to the Fund.

An investment in the Fund is not a bank deposit and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency.

PERFORMANCE INFORMATION

The following information provides some indication of the risks of investing in the Fund by showing how the Fund’s performance has varied over time. Class S Shares, Class A Shares, Class C Shares, and Class I Shares of the Fund commenced operations on July 6, 2009, after the reorganization of each corresponding class of shares of Janus Adviser INTECH Risk-Managed Growth Fund (“JAD predecessor fund”) into each respective share class of the Fund. Class T Shares of the Fund commenced operations on July 6, 2009.

• The performance shown for Class S Shares for periods prior to July 6, 2009, reflects the historical performance of the JAD predecessor fund’s Class S Shares prior to the reorganization, calculated using the fees and expenses of the JAD predecessor fund’s Class S Shares, net of any applicable fee and expense limitations or waivers.
• The performance shown for Class A Shares reflects the performance of the JAD predecessor fund’s Class A Shares from September 30, 2004 to July 6, 2009 (prior to the reorganization), calculated using the fees and expenses of Class A Shares of the JAD predecessor fund, net of any applicable fee and expense limitations or waivers. Performance shown for certain periods prior to September 30, 2004 reflects the historical performance of the JAD predecessor fund’s Class S Shares (formerly named Class I Shares), calculated using the fees and expenses of Class S Shares of the JAD predecessor fund, net of any applicable fee and expense limitations or waivers.
• The performance shown for Class C Shares for periods prior to July 6, 2009, reflects the historical performance of the JAD predecessor fund’s Class C Shares prior to the reorganization, calculated using the fees and expenses of the JAD predecessor fund’s Class C Shares, net of any applicable fee and expense limitations or waivers.
• The performance shown for Class I Shares reflects the performance of the JAD predecessor fund’s Class I Shares from November 28, 2005 to July 6, 2009 (prior to the reorganization), calculated using the fees and expenses of Class I Shares of the JAD predecessor fund, net of any applicable fee and expense limitations or waivers. Performance shown for certain periods prior to November 28, 2005 reflects the historical performance of the JAD predecessor fund’s Class S Shares (formerly named Class I Shares), calculated using the fees and expenses of Class S Shares of the JAD predecessor fund, net of any applicable fee and expense limitations or waivers.
• The performance shown for Class T Shares for periods prior to July 6, 2009, reflects the historical performance of the JAD predecessor fund’s Class S Shares prior to the reorganization, calculated using the fees and expenses of Class S Shares, net of any applicable fee and expense limitations or waivers.

If Class A Shares, Class I Shares, and Class T Shares of the Fund had been available during periods prior to July 6, 2009, the performance shown for each respective share class may have been different. The performance shown for periods following the Fund’s commencement of Class S Shares, Class A Shares, Class C Shares, Class I Shares, and Class T Shares reflects the fees and expenses of each respective share class, net of any applicable fee and expense limitations or waivers.

The bar chart depicts the change in performance from year to year during the periods indicated. The bar chart figures do not include any applicable sales charges that an investor may pay when they buy or sell Class A Shares or Class C Shares of the Fund. If sales charges were included, the returns would be lower. The table compares the Fund’s average annual returns for the periods indicated to a broad-based securities market index. The index is not actively managed and is not available for direct investment. All figures assume reinvestment of dividends and distributions. For certain periods, the Fund’s performance reflects the effect of expense waivers. Without the effect of these expense waivers, the performance shown would have been lower.

The Fund’s past performance (before and after taxes) does not necessarily indicate how it will perform in the future. Updated performance information is available at janus.com/advisor/mutual-funds or by calling 1-877-335-2687.

Annual Total Returns for Class S Shares (calendar year-end)

Best Quarter:  Second Quarter 2009  15.04%          Worst Quarter:  Fourth Quarter 2008  −25.11%

The Fund’s year-to-date return as of the calendar quarter ended September 30, 2013 was 20.79%.

Average Annual Total Returns (periods ended 12/31/12)

Average Annual Total Returns INTECH U.S. Growth Fund Class A, C, S, I, T Shares	Column	Label		1 Year	5 Years	Since Inception of Predecessor Fund	Inception Date
Class S Return Before Taxes	Class S Shares	Return Before Taxes		15.24%	0.95%	6.38%	Jan. 02, 2003
Class S Return After Taxes on Distributions	Class S Shares	Return After Taxes on Distributions		15.08%	0.84%	5.89%	Jan. 02, 2003
Class S Return After Taxes on Distributions and Sale of Fund Shares	Class S Shares	Return After Taxes on Distributions and Sale of Fund Shares		10.12%	0.79%	5.41%	Jan. 02, 2003
Class A Return Before Taxes	Class A Shares	Return Before Taxes	[1]	8.69%	(0.05%)	5.95%	Jan. 02, 2003
Class C Return Before Taxes	Class C Shares	Return Before Taxes	[2]	13.35%	0.29%	5.76%	Jan. 02, 2003
Class I Return Before Taxes	Class I Shares	Return Before Taxes		15.70%	1.41%	6.38%	Jan. 02, 2003
Class T Return Before Taxes	Class T Shares	Return Before Taxes		15.53%	0.95%	6.38%	Jan. 02, 2003
Russell 1000® Growth Index (reflects no deduction for expenses, fees, or taxes)		Russell 1000® Growth Index		15.26%	3.12%	7.16%	Jan. 02, 2003

After-tax returns are calculated using distributions for the Fund’s Class S Shares for periods following July 6, 2009; and for the JAD predecessor fund’s Class S Shares (formerly named Class I Shares) for periods prior to July 6, 2009. After-tax returns are calculated using the historically highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes. Actual after-tax returns depend on your individual tax situation and may differ from those shown in the preceding table. The after-tax return information shown above does not apply to Fund shares held through a tax-deferred account, such as a 401(k) plan or an IRA.

After-tax returns are only shown for Class S Shares of the Fund. After-tax returns for the other classes of Shares will vary from those shown for Class S Shares due to varying sales charges (as applicable), fees, and expenses among the classes.

[1] Calculated assuming maximum permitted sales loads.

[2] The one year return is calculated to include the contingent deferred sales charge.

XML

Label	Element	Value
Risk/Return:	rr_RiskReturnAbstract
Registrant Name	dei_EntityRegistrantName	JANUS INVESTMENT FUND
Prospectus Date	rr_ProspectusDate	Oct. 28, 2013
Janus Global Allocation Fund - Growth | Class A, C, S, I, T Shares
Risk/Return:	rr_RiskReturnAbstract
Risk/Return [Heading]	rr_RiskReturnHeading	FUND SUMMARY Janus Global Allocation Fund – Growth (formerly named Janus Growth Allocation Fund)
Objective [Heading]	rr_ObjectiveHeading	INVESTMENT OBJECTIVE
Objective, Primary [Text Block]	rr_ObjectivePrimaryTextBlock	Janus Global Allocation Fund – Growth seeks total return through a primary emphasis on growth of capital with a secondary emphasis on income.
Expense [Heading]	rr_ExpenseHeading	FEES AND EXPENSES OF THE FUND
Expense Narrative [Text Block]	rr_ExpenseNarrativeTextBlock	This table describes the fees and expenses that you may pay if you buy and hold Shares of the Fund. Each share class has different expenses, but represents an investment in the same Fund.
Shareholder Fees Caption [Text]	rr_ShareholderFeesCaption	SHAREHOLDER FEES (fees paid directly from your investment)
Operating Expenses Caption [Text]	rr_OperatingExpensesCaption	ANNUAL FUND OPERATING EXPENSES (expenses that you pay each year as a percentage of the value of your investment)
Portfolio Turnover [Heading]	rr_PortfolioTurnoverHeading	Portfolio Turnover:
Portfolio Turnover [Text Block]	rr_PortfolioTurnoverTextBlock	The Fund pays transaction costs, such as commissions, when it buys and sells securities (or “turns over” its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when Fund shares are held in a taxable account. These costs, which are not reflected in annual fund operating expenses or in the Example, affect the Fund’s performance. During the most recent fiscal year, the Fund’s portfolio turnover rate was 45% of the average value of its portfolio.
Portfolio Turnover, Rate	rr_PortfolioTurnoverRate	45.00%
Expense Breakpoint Discounts [Text]	rr_ExpenseBreakpointDiscounts	For Class A Shares, you may qualify for sales charge discounts if you and your family invest, or agree to invest in the future, at least $50,000 in the Fund or in other Janus mutual funds. More information about these and other discounts, as well as eligibility requirements for each share class, is available from your financial professional and in the “Purchases” section on page 52 of the Fund’s Prospectus and in the “Purchases” section on page 57 of the Fund’s Statement of Additional Information.
Expense Breakpoint, Minimum Investment Required [Amount]	rr_ExpenseBreakpointMinimumInvestmentRequiredAmount	$ 50,000
Expense Example [Heading]	rr_ExpenseExampleHeading	EXAMPLE:
Expense Example by Year [Heading]	rr_ExpenseExampleByYearHeading	The Example assumes that you invest $10,000 in the Fund for the time periods indicated and reinvest all dividends and distributions. The Example also assumes that your investment has a 5% return each year and that the Fund’s operating expenses (including the operating expenses of the underlying funds) remain the same. Although your actual costs may be higher or lower, based on these assumptions your costs would be:
Expense Example Narrative [Text Block]	rr_ExpenseExampleNarrativeTextBlock	The Example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds.
Expense Example by, Year, Caption [Text]	rr_ExpenseExampleByYearCaption	If Shares are redeemed:
Expense Example, No Redemption, By Year, Caption [Text]	rr_ExpenseExampleNoRedemptionByYearCaption	If Shares are not redeemed:
Strategy [Heading]	rr_StrategyHeading	PRINCIPAL INVESTMENT STRATEGIES
Strategy Narrative [Text Block]	rr_StrategyNarrativeTextBlock	The Fund seeks to achieve its investment objective by investing in other Janus mutual funds (“underlying funds”) that represent a variety of asset classes and investment styles and provide exposure to issuers that are economically tied to countries throughout the world. Through its investments in underlying funds, the Fund invests in issuers from several different countries and may, under unusual circumstances, be invested in a single country. As a result, the Fund normally will have approximately 40% of its net assets allocated to non-U.S. investments. The Fund may also have significant exposure to emerging markets. The Fund pursues this objective by investing in a diversified portfolio of underlying funds, resulting in an allocation of the Fund’s investments that normally provides exposure of approximately 75% to equity investments, 15% to fixed-income securities and money market instruments, and 10% to alternative investments. The target allocation and the allocation of the Fund’s assets among underlying funds are based on quantitative and qualitative analysis. Because it invests in other funds, the Fund is considered a “fund of funds.” The Fund’s asset allocation is intended to diversify investments throughout the world among equity investments, fixed-income securities, cash equivalents, and alternative investments. The portfolio manager determines the overall composition of the Fund, oversees the investment process, and is responsible for the day-to-day management of the Fund. The portfolio manager continually monitors asset class allocations and periodically rebalances the Fund’s investments in the underlying funds. The portfolio manager also regularly reviews the allocation of Fund assets in the underlying funds and may modify the underlying funds’ weightings or substitute other underlying funds to emphasize and mitigate risk exposures that may arise as a result of the implementation of the allocations. An independent asset allocation service provides evaluations of asset allocations that the portfolio manager may use in implementing the allocations among the underlying funds. Additionally, the portfolio manager consults with a committee (the “Janus Global Allocation Committee”) to regularly review the broad market, macroeconomic conditions and other global financial factors that may impact the Fund’s allocation of assets among the underlying funds and asset classes. The Janus Global Allocation Committee is comprised of investment professionals of Janus Capital and may also include investment professionals of Janus Capital’s affiliated investment advisers. The portfolio manager and Janus Global Allocation Committee normally meet on a quarterly basis. The portfolio manager may change the Fund’s asset class allocations, the underlying funds, an underlying fund’s asset category, or weightings among asset classes or underlying funds without prior shareholder notice. The Fund will normally allocate approximately 75% of its investments to underlying funds that provide varying exposure to common stocks of large U.S.-based companies, small- to mid-capitalization companies, and international companies (including those with exposure to emerging markets), approximately 15% of its investments to underlying bond funds and money market instruments, and approximately 10% of its investments to underlying funds that seek returns uncorrelated with the returns of stocks and bonds by providing exposure to alternative investments and alternative investment strategies. Refer to Appendix A in this Prospectus for a brief description of the investment strategies of each of the currently available underlying funds. When market conditions dictate a more defensive strategy, the Fund or an underlying fund may temporarily hold cash or invest its assets in temporary investments. In that case, the Fund may take positions that are inconsistent with its investment objective. As a result, the Fund may not achieve its investment objective.
Risk [Heading]	rr_RiskHeading	PRINCIPAL INVESTMENT RISKS
Risk Narrative [Text Block]	rr_RiskNarrativeTextBlock	The biggest risk is that the Fund’s returns will vary, and you could lose money. The Fund is designed for long-term investors seeking growth of capital and, to a lesser extent, income. Investments in a portfolio with common stock and alternative investment exposure tend to be more volatile than many other investment choices. Main Risks Associated with the Fund Allocation Risk. The Fund’s ability to achieve its investment objective depends largely upon the portfolio manager’s allocation of assets among the underlying funds and other securities, using the optimization process (a process that utilizes quantitative analysis of a number of factors, such as historical risk, performance, fund classifications, and the relationship among underlying funds) and the judgment of the portfolio manager. You could lose money on your investment in the Fund as a result of these allocations. The Fund will typically invest in a number of different underlying funds; however, to the extent that the Fund invests a significant portion of its assets in a single underlying fund, it will be more sensitive to the risks associated with that fund and any investments in which that fund focuses. Affiliated Fund Risk. Janus Capital has the authority to select and substitute underlying affiliated mutual funds. The fees paid to Janus Capital by some Janus mutual funds are generally higher than the fees paid to Janus Capital by the Fund or by other funds and share classes available for investment by the Fund. These conditions may create a conflict of interest when selecting underlying affiliated mutual funds and share classes for investment. Janus Capital, however, is a fiduciary to the Fund and its shareholders and is legally obligated to act in their best interest when selecting underlying affiliated mutual funds. Main Risks Associated with the Underlying Funds and Securities The biggest risk is that the underlying funds’ returns will vary, and you could lose money. Market Risk. Approximately 75% of the Fund’s assets are allocated to equity investments through investments in underlying funds. The value of an underlying fund’s portfolio may decrease if the value of an individual company or security, or multiple companies or securities, in the portfolio decreases or if a portfolio manager’s belief about a company’s intrinsic worth is incorrect. Further, regardless of how well individual companies or securities perform, the value of an underlying fund’s portfolio could also decrease if there are deteriorating economic or market conditions. It is important to understand that the value of your investment may fall, sometimes sharply, in response to changes in the market, and you could lose money. Foreign Exposure Risk. Certain underlying funds may have significant exposure to foreign markets as a result of their investments in foreign securities, including investments in emerging markets, which can be more volatile than the U.S. markets. As a result, an underlying fund’s returns and net asset value may be affected to a large degree by fluctuations in currency exchange rates or political or economic conditions in a particular country. A market swing in one or more countries or regions where an underlying fund has invested a significant amount of its assets may have a greater effect on an underlying fund’s performance than it would in a more geographically diversified portfolio. An underlying fund’s investments in emerging market countries may involve risks greater than, or in addition to, the risks of investing in more developed countries. Emerging Markets Risk. The risks of foreign investing mentioned above are heightened when investing in emerging markets. Emerging markets securities involve a number of additional risks, which may result from less government supervision and regulation of business and industry practices (including the potential lack of strict finance and accounting controls and standards), stock exchanges, brokers, and listed companies, making these investments potentially more volatile in price and less liquid than investments in developed securities markets, resulting in greater risk to investors. In addition, an underlying fund’s investments may be denominated in foreign currencies and therefore, changes in the value of a country’s currency compared to the U.S. dollar may affect the value of an underlying fund’s investments. To the extent that an underlying fund invests a significant portion of its assets in the securities of issuers in or companies of a single country or region, it is more likely to be impacted by events or conditions affecting that country or region, which could have a negative impact on the Fund’s performance. Some of the risks of investing directly in foreign and emerging market securities may be reduced when an underlying fund invests indirectly in foreign securities through various other investment vehicles including derivatives, which also involve other risks. Sovereign Debt Risk. An underlying fund may invest in U.S. and foreign government debt securities (“sovereign debt”). Investments in U.S. sovereign debt are considered low risk. However, investments in non-U.S. sovereign debt can involve a high degree of risk, including the risk that the governmental entity that controls the repayment of sovereign debt may not be willing or able to repay the principal and/or to pay the interest on its sovereign debt in a timely manner. A sovereign debtor’s willingness or ability to satisfy its debt obligation may be affected by various factors including, but not limited to, its cash flow situation, the extent of its foreign currency reserves, the availability of foreign exchange when a payment is due, and the relative size of its debt position in relation to its economy as a whole. In the event of default, there may be limited or no legal remedies for collecting sovereign debt and there may be no bankruptcy proceedings through which the underlying fund may collect all or part of the sovereign debt that a governmental entity has not repaid. Fixed-Income Securities Risk. Approximately 15% of the Fund’s assets are allocated to fixed-income securities through investments in underlying funds. Typically, the values of fixed-income securities change inversely with prevailing interest rates. Therefore, a fundamental risk of fixed-income securities is interest rate risk, which is the risk that the value of such securities will generally decline as prevailing interest rates rise, which may cause an underlying fund’s net asset value to likewise decrease. How specific fixed-income securities may react to changes in interest rates will depend on the specific characteristics of each security. Fixed-income securities are also subject to credit risk, prepayment risk, valuation risk, and liquidity risk. Credit risk is the risk that the credit strength of an issuer of a fixed-income security will weaken and/or that the issuer will be unable to make timely principal and interest payments and that the security may go into default. Prepayment risk is the risk that during periods of falling interest rates, certain fixed-income securities with higher interest rates, such as mortgage- and asset-backed securities, may be prepaid by their issuers thereby reducing the amount of interest payments. Valuation risk is the risk that one or more of the fixed-income securities in which an underlying fund invests are priced differently than the value realized upon such security’s sale. In times of market instability, valuation may be more difficult. Liquidity risk is the risk that fixed-income securities may be difficult or impossible to sell at the time that an underlying fund’s portfolio manager would like or at the price the portfolio manager believes the security is currently worth. Mortgage-Backed Securities Risk. Mortgage-backed securities are classified generally as either commercial mortgage-backed securities or residential mortgage-backed securities, each of which is subject to certain specific risks. Mortgage-backed securities tend to be more sensitive to changes in interest rates than other types of debt securities. Investments in mortgage-backed securities are subject to both extension risk, where borrowers extend the duration of their mortgages in times of rising interest rates, and prepayment risk, where borrowers pay off their mortgages sooner than expected in times of declining interest rates. These risks may reduce the Fund’s returns. In addition, investments in mortgage-backed securities, including those comprised of subprime mortgages, may be subject to a higher degree of credit risk, valuation risk, and liquidity risk than various other types of fixed-income securities. Alternative Investments Allocation Risk. Approximately 10% of the Fund’s assets are allocated to alternative investments through investments in underlying funds that invest in alternative investment strategies. In connection with the Fund’s allocation to alternative investments, the Fund may invest in a Janus underlying fund, Janus Diversified Alternatives Fund, which seeks returns uncorrelated with the returns generated by investments in stocks and bonds. In addition, as part of its alternative investments allocation, the Fund may invest in Janus Global Real Estate Fund. Janus Diversified Alternatives Fund’s ability to achieve its investment objective depends largely upon the successful evaluation of the risk, potential returns, and correlation properties with respect to its investments. There is a risk that the returns provided by alternative investments may be subject to high volatility and that an underlying fund’s portfolio manager’s beliefs about the expected returns, risk and correlation properties of one or more of an underlying fund’s investments may be incorrect. There is also a risk that an underlying fund’s investments will correlate with the performance of stocks and bonds to a greater degree than anticipated. Janus Capital does not have prior experience managing the investment strategy of Janus Diversified Alternatives Fund, and there is no guarantee that the investment techniques and analysis used by the underlying fund’s portfolio managers will produce the desired results. All of these factors may negatively affect your investment in the Fund and you could lose money. Investment in the underlying funds also involves derivatives, counterparty, leverage, real estate-related, and commodity-linked investment risks. Counterparty Risk. Certain derivative and “over-the-counter” instruments, such as swaps and forwards, are subject to the risk that the other party to a contract will not fulfill its contractual obligations. Commodity-Linked Investments Risk. Certain underlying funds may invest in derivatives that have exposure to the commodities markets. Such exposure may subject an underlying fund to greater volatility than investments in traditional securities. The value of a commodity-linked derivative investment typically is based upon the price movements of a physical commodity (such as heating oil, livestock, or agricultural products), a commodity futures contract or commodity index, or some other readily measurable economic variable. The value of commodity-linked derivative instruments may therefore be affected by changes in overall market movements, volatility of the underlying benchmark, changes in interest rates, or other factors affecting a particular industry or commodity such as drought, floods, weather, livestock disease, embargoes, tariffs, and international economic, political, and regulatory developments. Derivatives Risk. Certain underlying funds may invest in derivatives. Derivatives can be highly volatile and involve risks in addition to the risks of the underlying referenced securities. Gains or losses from a derivative investment can be substantially greater than the derivative’s original cost, and can therefore involve leverage. Leverage may cause an underlying fund to be more volatile than if it had not used leverage. Derivatives can be less liquid than other types of investments and entail the risk that the counterparty will default on its payment obligations. Exchange-Traded Funds Risk. Certain underlying funds may purchase shares of exchange-traded funds (“ETFs”) to gain exposure to a particular portion of the market. ETFs are pooled investment vehicles, which may be managed or unmanaged, that generally seek to track the performance of a specific index. ETFs are traded on an exchange at market prices that may vary from the net asset value of their underlying investments. When an underlying fund invests in an ETF, in addition to directly bearing the expenses associated with its own operations, it will bear a pro rata portion of the ETF’s expenses. ETFs have certain inherent risks generally associated with investments in a portfolio of securities in which the ETF is invested, including the risk that the general level of stock prices may decline, thereby adversely affecting the value of each unit of the ETF. ETFs also involve the risk that an active trading market for an ETF’s shares may not develop or be maintained. Exchange-Traded Notes Risk. Certain underlying funds may invest in exchange-traded notes (“ETNs”), which are debt securities whose returns are linked to a particular index. ETNs are typically linked to the performance of a commodities index that reflects the potential return on unleveraged investments in futures contracts of physical commodities, plus a specified rate of interest that could be earned on cash collateral. ETNs are subject to credit risk and counterparty risk. The value of an ETN may vary and may be influenced by time to maturity, level of supply and demand for the ETN, volatility and lack of liquidity in underlying commodities markets, changes in the applicable interest rates, changes in the issuer’s credit rating, and economic, legal, political, or geographic events that affect the referenced commodity. When an underlying fund invests in ETNs it will bear its proportionate share of any fees and expenses borne by the ETN. There may be restrictions on an underlying fund’s right to redeem its investment in an ETN, which is meant to be held until maturity. An underlying fund’s decision to sell its ETN holdings may be limited by the availability of a secondary market. An investment in the Fund is not a bank deposit and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency.
Risk Lose Money [Text]	rr_RiskLoseMoney	The biggest risk is that the Fund’s returns will vary, and you could lose money.
Risk Not Insured Depository Institution [Text]	rr_RiskNotInsuredDepositoryInstitution	An investment in the Fund is not a bank deposit and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency.
Bar Chart and Performance Table [Heading]	rr_BarChartAndPerformanceTableHeading	PERFORMANCE INFORMATION
Performance Narrative [Text Block]	rr_PerformanceNarrativeTextBlock	The following information provides some indication of the risks of investing in the Fund by showing how the Fund’s performance has varied over time. Class T Shares (formerly named Class J Shares, the initial share class) of the Fund commenced operations with the Fund’s inception. Class A Shares, Class C Shares, Class S Shares, and Class I Shares of the Fund commenced operations on July 6, 2009. The performance shown for Class T Shares is calculated using the fees and expenses of Class T Shares in effect during the periods shown, net of any applicable fee and expense limitations or waivers. The performance shown for Class A Shares, Class C Shares, and Class S Shares for periods prior to July 6, 2009, reflects the performance of the Fund’s former Class J Shares, calculated using the fees and expenses of each respective share class, without the effect of any fee and expense limitations or waivers. The performance shown for Class I Shares for periods prior to July 6, 2009, reflects the performance of the Fund’s former Class J Shares, calculated using the fees and expenses of Class J Shares, net of any applicable fee and expense limitations or waivers. If Class A Shares, Class C Shares, Class S Shares, and Class I Shares of the Fund had been available during periods prior to July 6, 2009, the performance shown for each respective share class may have been different. The performance shown for periods following the Fund’s commencement of Class A Shares, Class C Shares, Class S Shares, and Class I Shares reflects the fees and expenses of each respective share class, net of any applicable fee and expense limitations or waivers. The bar chart depicts the change in performance from year to year during the periods indicated. Performance information for each underlying fund is available in its prospectus and/or the most recent annual or semiannual report. The bar chart figures do not include any applicable sales charges that an investor may pay when they buy or sell Class A Shares or Class C Shares of the Fund. If sales charges were included, the returns would be lower. The table compares the Fund’s average annual returns for the periods indicated to broad-based securities market indices. The indices are not actively managed and are not available for direct investment. All figures assume reinvestment of dividends and distributions. For certain periods, the Fund’s performance reflects the effect of expense waivers. Without the effect of these expense waivers, the performance shown would have been lower. The Fund’s past performance (before and after taxes) does not necessarily indicate how it will perform in the future. Updated performance information is available at janus.com/advisor/mutual-funds or by calling 1-877-335-2687.
Performance Information Illustrates Variability of Returns [Text]	rr_PerformanceInformationIllustratesVariabilityOfReturns	The following information provides some indication of the risks of investing in the Fund by showing how the Fund’s performance has varied over time. The bar chart depicts the change in performance from year to year during the periods indicated.
Performance Additional Market Index [Text]	rr_PerformanceAdditionalMarketIndex	The table compares the Fund’s average annual returns for the periods indicated to broad-based securities market indices. The indices are not actively managed and are not available for direct investment. All figures assume reinvestment of dividends and distributions.
Performance Availability Phone [Text]	rr_PerformanceAvailabilityPhone	1-877-335-2687
Performance Availability Website Address [Text]	rr_PerformanceAvailabilityWebSiteAddress	janus.com/advisor/mutual-funds
Performance Past Does Not Indicate Future [Text]	rr_PerformancePastDoesNotIndicateFuture	The Fund’s past performance (before and after taxes) does not necessarily indicate how it will perform in the future.
Bar Chart [Heading]	rr_BarChartHeading	Annual Total Returns for Class T Shares (calendar year-end)
Bar Chart Does Not Reflect Sales Loads [Text]	rr_BarChartDoesNotReflectSalesLoads	The bar chart figures do not include any applicable sales charges that an investor may pay when they buy or sell Class A Shares or Class C Shares of the Fund. If sales charges were included, the returns would be lower.
Bar Chart Closing [Text Block]	rr_BarChartClosingTextBlock	Best Quarter:  Second Quarter 2009  18.37%          Worst Quarter:  Fourth Quarter 2008  −18.05%
Year to Date Return, Label	rr_YearToDateReturnLabel	The Fund’s year-to-date return as of the calendar quarter ended September 30, 2013 was 12.39%.
Performance Table Heading	rr_PerformanceTableHeading	Average Annual Total Returns (periods ended 12/31/12)
Performance Table Uses Highest Federal Rate	rr_PerformanceTableUsesHighestFederalRate	After-tax returns are calculated using the historically highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes.
Performance Table Not Relevant to Tax Deferred	rr_PerformanceTableNotRelevantToTaxDeferred	Actual after-tax returns depend on your individual tax situation and may differ from those shown in the preceding table. The after-tax return information shown above does not apply to Fund shares held through a tax-deferred account, such as a 401(k) plan or an IRA.
Performance Table One Class of after Tax Shown [Text]	rr_PerformanceTableOneClassOfAfterTaxShown	After-tax returns are only shown for Class T Shares of the Fund. After-tax returns for the other classes of Shares will vary from those shown for Class T Shares due to varying sales charges (as applicable), fees, and expenses among the classes.
Performance Table Explanation after Tax Higher	rr_PerformanceTableExplanationAfterTaxHigher	If the Fund incurs a loss, which generates a tax benefit, the Return After Taxes on Distributions and Sale of Fund Shares may exceed the Fund’s other return figures.
Performance Table Narrative	rr_PerformanceTableNarrativeTextBlock	Effective February 15, 2013, the Fund’s primary benchmark index changed from the S&P 500® Index to the Morgan Stanley Capital International (“MSCI”) All Country World IndexSM to reflect the global investment strategies of the Fund. Additionally, the Fund changed the name of its secondary benchmark index from Growth Allocation Index to Global Growth Allocation Index and its composition from an internally-calculated, hypothetical combination of unmanaged indices that combines total returns from the Dow Jones Wilshire 5000 Index (50%), the MSCI EAFE® Index (25%), the Barclays U.S. Aggregate Bond Index (20%), and the MSCI Emerging Markets Free IndexSM (5%) to an internally-calculated, hypothetical combination of unmanaged indices that combines total returns from the MSCI All Country World IndexSM (80%) and the Barclays Global Aggregate Bond Index (20%). The MSCI All Country World IndexSM is an unmanaged, free float-adjusted market capitalization weighted index that is designed to measure the equity market performance of global developed and emerging markets. Janus Capital believes that the foregoing benchmark index changes provide a more appropriate representation of the Fund’s revised investment strategy that includes an increased focus on global investments, including emerging markets. After-tax returns are calculated using distributions for the Fund’s Class T Shares (formerly named Class J Shares, the initial share class). After-tax returns are calculated using the historically highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes. Actual after-tax returns depend on your individual tax situation and may differ from those shown in the preceding table. The after-tax return information shown above does not apply to Fund shares held through a tax-deferred account, such as a 401(k) plan or an IRA. After-tax returns are only shown for Class T Shares of the Fund. After-tax returns for the other classes of Shares will vary from those shown for Class T Shares due to varying sales charges (as applicable), fees, and expenses among the classes.
Performance Table Closing [Text Block]	rr_PerformanceTableClosingTextBlock	Updated performance information is available at janus.com/advisor/mutual-funds or by calling 1-877-335-2687.
Janus Global Allocation Fund - Growth | Class A, C, S, I, T Shares | Class A
Risk/Return:	rr_RiskReturnAbstract
Shareholder Fees Column [Text]	rr_ShareholderFeesColumnName	Class A
Maximum Sales Charge (load) Imposed on Purchases (as a percentage of offering price)	rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice	5.75%
Maximum Deferred Sales Charge (load) (as a percentage of the lower of original purchase price or redemption proceeds)	rr_MaximumDeferredSalesChargeOverOther	none
Operating Expenses Column [Text]	rr_OperatingExpensesColumnName	Class A
Management Fees	rr_ManagementFeesOverAssets	0.05%
Distribution/Service (12b-1) Fees	rr_DistributionAndService12b1FeesOverAssets	0.25%
Other Expenses	rr_OtherExpensesOverAssets	0.11%
Acquired Fund Fees and Expenses	rr_AcquiredFundFeesAndExpensesOverAssets	0.71%
Total Annual Fund Operating Expenses	rr_ExpensesOverAssets	1.12%
Expense Example, By Year, Column [Text]	rr_ExpenseExampleByYearColumnName	Class A Shares
1 Year	rr_ExpenseExampleYear01	683
3 Years	rr_ExpenseExampleYear03	911
5 Years	rr_ExpenseExampleYear05	1,156
10 Years	rr_ExpenseExampleYear10	1,860
Expense Example, No Redemption, By Year, Column [Text]	rr_ExpenseExampleNoRedemptionByYearColumnName	Class A Shares
1 Year	rr_ExpenseExampleNoRedemptionYear01	683
3 Years	rr_ExpenseExampleNoRedemptionYear03	911
5 Years	rr_ExpenseExampleNoRedemptionYear05	1,156
10 Years	rr_ExpenseExampleNoRedemptionYear10	1,860
Janus Global Allocation Fund - Growth | Class A, C, S, I, T Shares | Class C
Risk/Return:	rr_RiskReturnAbstract
Shareholder Fees Column [Text]	rr_ShareholderFeesColumnName	Class C
Maximum Sales Charge (load) Imposed on Purchases (as a percentage of offering price)	rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice	none
Maximum Deferred Sales Charge (load) (as a percentage of the lower of original purchase price or redemption proceeds)	rr_MaximumDeferredSalesChargeOverOther	1.00%
Operating Expenses Column [Text]	rr_OperatingExpensesColumnName	Class C
Management Fees	rr_ManagementFeesOverAssets	0.05%
Distribution/Service (12b-1) Fees	rr_DistributionAndService12b1FeesOverAssets	1.00%
Other Expenses	rr_OtherExpensesOverAssets	0.16%
Acquired Fund Fees and Expenses	rr_AcquiredFundFeesAndExpensesOverAssets	0.71%
Total Annual Fund Operating Expenses	rr_ExpensesOverAssets	1.92%
Expense Example, By Year, Column [Text]	rr_ExpenseExampleByYearColumnName	Class C Shares
1 Year	rr_ExpenseExampleYear01	295
3 Years	rr_ExpenseExampleYear03	603
5 Years	rr_ExpenseExampleYear05	1,037
10 Years	rr_ExpenseExampleYear10	2,243
Expense Example, No Redemption, By Year, Column [Text]	rr_ExpenseExampleNoRedemptionByYearColumnName	Class C Shares
1 Year	rr_ExpenseExampleNoRedemptionYear01	195
3 Years	rr_ExpenseExampleNoRedemptionYear03	603
5 Years	rr_ExpenseExampleNoRedemptionYear05	1,037
10 Years	rr_ExpenseExampleNoRedemptionYear10	2,243
Janus Global Allocation Fund - Growth | Class A, C, S, I, T Shares | Class S
Risk/Return:	rr_RiskReturnAbstract
Shareholder Fees Column [Text]	rr_ShareholderFeesColumnName	Class S
Maximum Sales Charge (load) Imposed on Purchases (as a percentage of offering price)	rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice	none
Maximum Deferred Sales Charge (load) (as a percentage of the lower of original purchase price or redemption proceeds)	rr_MaximumDeferredSalesChargeOverOther	none
Operating Expenses Column [Text]	rr_OperatingExpensesColumnName	Class S
Management Fees	rr_ManagementFeesOverAssets	0.05%
Distribution/Service (12b-1) Fees	rr_DistributionAndService12b1FeesOverAssets	0.25%
Other Expenses	rr_OtherExpensesOverAssets	0.31%
Acquired Fund Fees and Expenses	rr_AcquiredFundFeesAndExpensesOverAssets	0.71%
Total Annual Fund Operating Expenses	rr_ExpensesOverAssets	1.32%
Expense Example, By Year, Column [Text]	rr_ExpenseExampleByYearColumnName	Class S Shares
1 Year	rr_ExpenseExampleYear01	134
3 Years	rr_ExpenseExampleYear03	418
5 Years	rr_ExpenseExampleYear05	723
10 Years	rr_ExpenseExampleYear10	1,590
Expense Example, No Redemption, By Year, Column [Text]	rr_ExpenseExampleNoRedemptionByYearColumnName	Class S Shares
1 Year	rr_ExpenseExampleNoRedemptionYear01	134
3 Years	rr_ExpenseExampleNoRedemptionYear03	418
5 Years	rr_ExpenseExampleNoRedemptionYear05	723
10 Years	rr_ExpenseExampleNoRedemptionYear10	1,590
Janus Global Allocation Fund - Growth | Class A, C, S, I, T Shares | Class I
Risk/Return:	rr_RiskReturnAbstract
Shareholder Fees Column [Text]	rr_ShareholderFeesColumnName	Class I
Maximum Sales Charge (load) Imposed on Purchases (as a percentage of offering price)	rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice	none
Maximum Deferred Sales Charge (load) (as a percentage of the lower of original purchase price or redemption proceeds)	rr_MaximumDeferredSalesChargeOverOther	none
Operating Expenses Column [Text]	rr_OperatingExpensesColumnName	Class I
Management Fees	rr_ManagementFeesOverAssets	0.05%
Distribution/Service (12b-1) Fees	rr_DistributionAndService12b1FeesOverAssets	none
Other Expenses	rr_OtherExpensesOverAssets	0.15%
Acquired Fund Fees and Expenses	rr_AcquiredFundFeesAndExpensesOverAssets	0.71%
Total Annual Fund Operating Expenses	rr_ExpensesOverAssets	0.91%
Expense Example, By Year, Column [Text]	rr_ExpenseExampleByYearColumnName	Class I Shares
1 Year	rr_ExpenseExampleYear01	93
3 Years	rr_ExpenseExampleYear03	290
5 Years	rr_ExpenseExampleYear05	504
10 Years	rr_ExpenseExampleYear10	1,120
Expense Example, No Redemption, By Year, Column [Text]	rr_ExpenseExampleNoRedemptionByYearColumnName	Class I Shares
1 Year	rr_ExpenseExampleNoRedemptionYear01	93
3 Years	rr_ExpenseExampleNoRedemptionYear03	290
5 Years	rr_ExpenseExampleNoRedemptionYear05	504
10 Years	rr_ExpenseExampleNoRedemptionYear10	1,120
Janus Global Allocation Fund - Growth | Class A, C, S, I, T Shares | Class T
Risk/Return:	rr_RiskReturnAbstract
Shareholder Fees Column [Text]	rr_ShareholderFeesColumnName	Class T
Maximum Sales Charge (load) Imposed on Purchases (as a percentage of offering price)	rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice	none
Maximum Deferred Sales Charge (load) (as a percentage of the lower of original purchase price or redemption proceeds)	rr_MaximumDeferredSalesChargeOverOther	none
Operating Expenses Column [Text]	rr_OperatingExpensesColumnName	Class T
Management Fees	rr_ManagementFeesOverAssets	0.05%
Distribution/Service (12b-1) Fees	rr_DistributionAndService12b1FeesOverAssets	none
Other Expenses	rr_OtherExpensesOverAssets	0.31%
Acquired Fund Fees and Expenses	rr_AcquiredFundFeesAndExpensesOverAssets	0.71%
Total Annual Fund Operating Expenses	rr_ExpensesOverAssets	1.07%
Expense Example, By Year, Column [Text]	rr_ExpenseExampleByYearColumnName	Class T Shares
1 Year	rr_ExpenseExampleYear01	109
3 Years	rr_ExpenseExampleYear03	340
5 Years	rr_ExpenseExampleYear05	590
10 Years	rr_ExpenseExampleYear10	1,306
Expense Example, No Redemption, By Year, Column [Text]	rr_ExpenseExampleNoRedemptionByYearColumnName	Class T Shares
1 Year	rr_ExpenseExampleNoRedemptionYear01	109
3 Years	rr_ExpenseExampleNoRedemptionYear03	340
5 Years	rr_ExpenseExampleNoRedemptionYear05	590
10 Years	rr_ExpenseExampleNoRedemptionYear10	$ 1,306
2006	rr_AnnualReturn2006	18.51%
2007	rr_AnnualReturn2007	15.73%
2008	rr_AnnualReturn2008	(34.91%)
2009	rr_AnnualReturn2009	35.79%
2010	rr_AnnualReturn2010	13.40%
2011	rr_AnnualReturn2011	(6.49%)
2012	rr_AnnualReturn2012	14.79%
Bar Chart, Year to Date Return, Date	rr_BarChartYearToDateReturnDate	Sep. 30, 2013
Bar Chart, Year to Date Return	rr_BarChartYearToDateReturn	12.39%
Highest Quarterly Return, Label	rr_HighestQuarterlyReturnLabel	Best Quarter:
Highest Quarterly Return, Date	rr_BarChartHighestQuarterlyReturnDate	Jun. 30, 2009
Highest Quarterly Return	rr_BarChartHighestQuarterlyReturn	18.37%
Lowest Quarterly Return, Label	rr_LowestQuarterlyReturnLabel	Worst Quarter:
Lowest Quarterly Return, Date	rr_BarChartLowestQuarterlyReturnDate	Dec. 31, 2008
Lowest Quarterly Return	rr_BarChartLowestQuarterlyReturn	(18.05%)
Janus Global Allocation Fund - Growth | Class A, C, S, I, T Shares | Return Before Taxes | Class A
Risk/Return:	rr_RiskReturnAbstract
Column	rr_AverageAnnualReturnColumnName	Class A Shares
Label	rr_AverageAnnualReturnLabel	Return Before Taxes	[1]
1 Year	rr_AverageAnnualReturnYear01	8.09%
5 Years	rr_AverageAnnualReturnYear05	0.16%
Since Inception	rr_AverageAnnualReturnSinceInception	4.68%
Inception Date	rr_AverageAnnualReturnInceptionDate	Dec. 30, 2005
Janus Global Allocation Fund - Growth | Class A, C, S, I, T Shares | Return Before Taxes | Class C
Risk/Return:	rr_RiskReturnAbstract
Column	rr_AverageAnnualReturnColumnName	Class C Shares
Label	rr_AverageAnnualReturnLabel	Return Before Taxes	[2]
1 Year	rr_AverageAnnualReturnYear01	12.53%
5 Years	rr_AverageAnnualReturnYear05	0.57%
Since Inception	rr_AverageAnnualReturnSinceInception	4.77%
Inception Date	rr_AverageAnnualReturnInceptionDate	Dec. 30, 2005
Janus Global Allocation Fund - Growth | Class A, C, S, I, T Shares | Return Before Taxes | Class S
Risk/Return:	rr_RiskReturnAbstract
Column	rr_AverageAnnualReturnColumnName	Class S Shares
Label	rr_AverageAnnualReturnLabel	Return Before Taxes
1 Year	rr_AverageAnnualReturnYear01	14.54%
5 Years	rr_AverageAnnualReturnYear05	1.15%
Since Inception	rr_AverageAnnualReturnSinceInception	5.34%
Inception Date	rr_AverageAnnualReturnInceptionDate	Dec. 30, 2005
Janus Global Allocation Fund - Growth | Class A, C, S, I, T Shares | Return Before Taxes | Class I
Risk/Return:	rr_RiskReturnAbstract
Column	rr_AverageAnnualReturnColumnName	Class I Shares
Label	rr_AverageAnnualReturnLabel	Return Before Taxes
1 Year	rr_AverageAnnualReturnYear01	15.05%
5 Years	rr_AverageAnnualReturnYear05	1.47%
Since Inception	rr_AverageAnnualReturnSinceInception	5.71%
Inception Date	rr_AverageAnnualReturnInceptionDate	Dec. 30, 2005
Janus Global Allocation Fund - Growth | Class A, C, S, I, T Shares | Return Before Taxes | Class T
Risk/Return:	rr_RiskReturnAbstract
Column	rr_AverageAnnualReturnColumnName	Class T Shares
Label	rr_AverageAnnualReturnLabel	Return Before Taxes
1 Year	rr_AverageAnnualReturnYear01	14.79%
5 Years	rr_AverageAnnualReturnYear05	1.47%
Since Inception	rr_AverageAnnualReturnSinceInception	5.71%
Inception Date	rr_AverageAnnualReturnInceptionDate	Dec. 30, 2005
Janus Global Allocation Fund - Growth | Class A, C, S, I, T Shares | Return After Taxes on Distributions | Class T
Risk/Return:	rr_RiskReturnAbstract
Column	rr_AverageAnnualReturnColumnName	Class T Shares
Label	rr_AverageAnnualReturnLabel	Return After Taxes on Distributions
1 Year	rr_AverageAnnualReturnYear01	14.29%
5 Years	rr_AverageAnnualReturnYear05	0.98%
Since Inception	rr_AverageAnnualReturnSinceInception	5.12%
Inception Date	rr_AverageAnnualReturnInceptionDate	Dec. 30, 2005
Janus Global Allocation Fund - Growth | Class A, C, S, I, T Shares | Return After Taxes on Distributions and Sale of Fund Shares | Class T
Risk/Return:	rr_RiskReturnAbstract
Column	rr_AverageAnnualReturnColumnName	Class T Shares
Label	rr_AverageAnnualReturnLabel	Return After Taxes on Distributions and Sale of Fund Shares	[3]
1 Year	rr_AverageAnnualReturnYear01	9.91%
5 Years	rr_AverageAnnualReturnYear05	1.02%
Since Inception	rr_AverageAnnualReturnSinceInception	4.68%
Inception Date	rr_AverageAnnualReturnInceptionDate	Dec. 30, 2005
Janus Global Allocation Fund - Growth | Class A, C, S, I, T Shares | Morgan Stanley Capital International All Country World Index℠ (net of foreign withholding taxes) (reflects no deduction for expenses, fees, or taxes, except foreign withholding taxes)
Risk/Return:	rr_RiskReturnAbstract
Label	rr_AverageAnnualReturnLabel	Morgan Stanley Capital International All Country World IndexSM (net of foreign withholding taxes)
1 Year	rr_AverageAnnualReturnYear01	16.13%
5 Years	rr_AverageAnnualReturnYear05	(1.16%)
Since Inception	rr_AverageAnnualReturnSinceInception	3.52%
Inception Date	rr_AverageAnnualReturnInceptionDate	Dec. 30, 2005
Janus Global Allocation Fund - Growth | Class A, C, S, I, T Shares | Global Growth Allocation Index (reflects no deduction for expenses, fees, or taxes, except any applicable foreign withholding taxes)
Risk/Return:	rr_RiskReturnAbstract
Label	rr_AverageAnnualReturnLabel	Global Growth Allocation Index
1 Year	rr_AverageAnnualReturnYear01	13.80%
5 Years	rr_AverageAnnualReturnYear05	0.43%
Since Inception	rr_AverageAnnualReturnSinceInception	4.30%
Inception Date	rr_AverageAnnualReturnInceptionDate	Dec. 30, 2005
Janus Global Allocation Fund - Growth | Class A, C, S, I, T Shares | S&P 500® Index (reflects no deduction for expenses, fees, or taxes)
Risk/Return:	rr_RiskReturnAbstract
Label	rr_AverageAnnualReturnLabel	S&P 500® Index
1 Year	rr_AverageAnnualReturnYear01	16.00%
5 Years	rr_AverageAnnualReturnYear05	1.66%
Since Inception	rr_AverageAnnualReturnSinceInception	4.12%
Inception Date	rr_AverageAnnualReturnInceptionDate	Dec. 30, 2005
Janus Global Allocation Fund - Growth | Class A, C, S, I, T Shares | Growth Allocation Index (reflects no deduction for expenses, fees, or taxes, except any applicable foreign withholding taxes)
Risk/Return:	rr_RiskReturnAbstract
Label	rr_AverageAnnualReturnLabel	Growth Allocation Index
1 Year	rr_AverageAnnualReturnYear01	14.29%
5 Years	rr_AverageAnnualReturnYear05	1.76%
Since Inception	rr_AverageAnnualReturnSinceInception	4.81%
Inception Date	rr_AverageAnnualReturnInceptionDate	Dec. 30, 2005

[1] Calculated assuming maximum permitted sales loads.

[2] The one year return is calculated to include the contingent deferred sales charge.

[3] If the Fund incurs a loss, which generates a tax benefit, the Return After Taxes on Distributions and Sale of Fund Shares may exceed the Fund’s other return figures.

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Janus High-Yield Fund | Class D Shares

FUND SUMMARY

Janus High-Yield Fund

INVESTMENT OBJECTIVES

Janus High-Yield Fund seeks to obtain high current income.

Capital appreciation is a secondary investment objective when consistent with its primary investment objective.

FEES AND EXPENSES OF THE FUND

This table describes the fees and expenses that you may pay if you buy and hold Shares of the Fund.

ANNUAL FUND OPERATING EXPENSES
(expenses that you pay each year as a percentage of the value of your investment)

Annual Fund Operating Expenses	Janus High-Yield Fund Class D Shares Class D
Operating Expenses Column [Text]	Class D
Management Fees	0.56%
Other Expenses	0.21%
Total Annual Fund Operating Expenses	0.77%

EXAMPLE:

The Example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds.

The Example assumes that you invest $10,000 in the Fund for the time periods indicated, reinvest all dividends and distributions, and then redeem all of your Shares at the end of each period. The Example also assumes that your investment has a 5% return each year and that the Fund’s operating expenses remain the same. Although your actual costs may be higher or lower, based on these assumptions your costs would be:

Expense Example (USD $)	Expense Example, By Year, Column [Text]	1 Year	3 Years	5 Years	10 Years
Janus High-Yield Fund Class D Shares Class D	Class D Shares	79	246	428	954

Portfolio Turnover: 

The Fund pays transaction costs, such as commissions, when it buys and sells securities (or “turns over” its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when Fund shares are held in a taxable account. These costs, which are not reflected in annual fund operating expenses or in the Example, affect the Fund’s performance. During the most recent fiscal year, the Fund’s portfolio turnover rate was 93% of the average value of its portfolio.

PRINCIPAL INVESTMENT STRATEGIES

The Fund pursues its investment objectives by investing, under normal circumstances, at least 80% of its net assets in high-yield/high-risk securities rated below investment grade. Securities rated below investment grade may include their unrated equivalents or other high-yielding securities the portfolio managers believe offer attractive risk/return characteristics. The Fund may at times invest all of its assets in such securities. The Fund may also invest in bank loans, money market instruments, and foreign debt securities (which may include investments in emerging markets). Due to the nature of securities in which the Fund invests, it may have relatively high portfolio turnover compared to other funds.

In addition, the Fund may invest its assets in derivatives, which are instruments that have a value derived from, or directly linked to, an underlying asset, such as equity securities, fixed-income securities, commodities, currencies, interest rates, or market indices. In particular, the Fund may use interest rate futures to manage portfolio risk. The Fund’s exposure to derivatives will vary. For purposes of meeting its 80% investment policy, the Fund may include derivatives that have characteristics similar to the securities in which the Fund may directly invest.

In addition to considering economic factors such as the effect of interest rates on the Fund’s investments, the portfolio managers apply a “bottom up” approach in choosing investments. This means that the portfolio managers look at income-producing securities one at a time to determine if a security is an attractive investment opportunity and if it is consistent with the Fund’s investment policies.

The Fund may lend portfolio securities on a short-term or long-term basis, in an amount equal to up to 1/3 of its total assets as determined at the time of the loan origination.

PRINCIPAL INVESTMENT RISKS

Although the Fund may be less volatile than funds that invest most of their assets in common stocks, the Fund’s returns and yields will vary, and you could lose money.

Fixed-Income Securities Risk. The Fund invests in a variety of fixed-income securities. Typically, the values of fixed-income securities change inversely with prevailing interest rates. Therefore, a fundamental risk of fixed-income securities is interest rate risk, which is the risk that the value of such securities will generally decline as prevailing interest rates rise, which may cause the Fund’s net asset value to likewise decrease. How specific fixed-income securities may react to changes in interest rates will depend on the specific characteristics of each security. Fixed-income securities are also subject to credit risk, prepayment risk, valuation risk, and liquidity risk. Credit risk is the risk that the credit strength of an issuer of a fixed-income security will weaken and/or that the issuer will be unable to make timely principal and interest payments and that the security may go into default. Prepayment risk is the risk that during periods of falling interest rates, certain fixed-income securities with higher interest rates, such as mortgage- and asset-backed securities, may be prepaid by their issuers thereby reducing the amount of interest payments. Valuation risk is the risk that one or more of the fixed-income securities in which the Fund invests are priced differently than the value realized upon such security’s sale. In times of market instability, valuation may be more difficult. Liquidity risk is the risk that fixed-income securities may be difficult or impossible to sell at the time that the portfolio managers would like or at the price the portfolio managers believe the security is currently worth.

High-Yield/High-Risk Bond Risk. The Fund may invest without limit in higher-yielding/higher-risk bonds, also known as “junk” bonds. High-yield/high-risk bonds may be more sensitive than other types of bonds to economic changes, political changes, or adverse developments specific to the company that issued the bond, which may adversely affect their value.

Bank Loan Risk. Bank loans are obligations of companies or other entities entered into in connection with recapitalizations, acquisitions, and refinancings. The Fund’s investments in bank loans are generally acquired as a participation interest in, or assignment of, loans originated by a lender or other financial institution. These investments may include institutionally-traded floating and fixed-rate debt securities. Participation interests and assignments involve credit, interest rate, and liquidity risk. In addition, the bank loans underlying these securities often involve borrowers with low credit ratings whose financial conditions are troubled or uncertain, including companies that are highly leveraged or in bankruptcy proceedings.

Foreign Exposure Risk. The Fund may have exposure to foreign markets as a result of its investments in foreign securities, including investments in emerging markets, which can be more volatile than the U.S. markets. As a result, its returns and net asset value may be affected to a large degree by fluctuations in currency exchange rates or political or economic conditions in a particular country. In some foreign markets, there may not be protection against failure by other parties to complete transactions. It may not be possible for the Fund to repatriate capital, dividends, interest, and other income from a particular country or governmental entity. In addition, a market swing in one or more countries or regions where the Fund has invested a significant amount of its assets may have a greater effect on the Fund’s performance than it would in a more geographically diversified portfolio. To the extent the Fund invests in foreign debt securities, such investments are sensitive to changes in interest rates. Additionally, investments in securities of foreign governments involve the risk that a foreign government may not be willing or able to pay interest or repay principal when due. The Fund’s investments in emerging market countries may involve risks greater than, or in addition to, the risks of investing in more developed countries.

Portfolio Turnover Risk. Increased portfolio turnover may result in higher costs, which may have a negative effect on the Fund’s performance. In addition, higher portfolio turnover may result in the acceleration of capital gains and the recognition of greater levels of short-term capital gains, which are taxed at ordinary federal income tax rates when distributed to shareholders.

Derivatives Risk. Derivatives can be highly volatile and involve risks in addition to the risks of the underlying referenced securities. Gains or losses from a derivative investment can be substantially greater than the derivative’s original cost, and can therefore involve leverage. Leverage may cause the Fund to be more volatile than if it had not used leverage. Derivatives can be less liquid than other types of investments and entail the risk that the counterparty will default on its payment obligations.

Securities Lending Risk. The Fund may seek to earn additional income through lending its securities to certain qualified broker-dealers and institutions. There is the risk that when portfolio securities are lent, the securities may not be returned on a timely basis, and the Fund may experience delays and costs in recovering the security or gaining access to the collateral provided to the Fund to collateralize the loan. If the Fund is unable to recover a security on loan, the Fund may use the collateral to purchase replacement securities in the market. There is a risk that the value of the collateral could decrease below the cost of the replacement security by the time the replacement investment is made, resulting in a loss to the Fund.

An investment in the Fund is not a bank deposit and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency.

PERFORMANCE INFORMATION

The following information provides some indication of the risks of investing in the Fund by showing how the Fund’s performance has varied over time. Class D Shares of the Fund commenced operations on February 16, 2010, as a result of the restructuring of Class J Shares, the predecessor share class. The performance shown for Class D Shares for periods prior to February 16, 2010, reflects the performance of the Fund’s former Class J Shares, calculated using the fees and expenses in effect during the periods shown, net of any applicable fee and expense limitations or waivers. If Class D Shares of the Fund had been available during periods prior to February 16, 2010, the performance shown may have been different. The performance shown for periods following the Fund’s commencement of Class D Shares reflects the fees and expenses of Class D Shares, net of any applicable fee and expense limitations or waivers.

The bar chart depicts the change in performance from year to year during the periods indicated. The table compares the Fund’s average annual returns for the periods indicated to a broad-based securities market index. The index is not actively managed and is not available for direct investment. All figures assume reinvestment of dividends and distributions. For certain periods, the Fund’s performance reflects the effect of expense waivers. Without the effect of these expense waivers, the performance shown would have been lower.

The Fund’s past performance (before and after taxes) does not necessarily indicate how it will perform in the future. Updated performance information is available at janus.com/allfunds or by calling 1-800-525-3713.

Annual Total Returns for Class D Shares (calendar year-end)

Best Quarter:  Second Quarter 2009  14.93%          Worst Quarter:  Fourth Quarter 2008  −12.96%

The Fund’s year-to-date return as of the calendar quarter ended September 30, 2013 was 3.61%.

Average Annual Total Returns (periods ended 12/31/12)

Average Annual Total Returns Janus High-Yield Fund Class D Shares	Column	Label		1 Year	5 Years	10 Years	Since Inception	Inception Date
Class D Return Before Taxes	Class D Shares	Return Before Taxes		14.40%	9.24%	8.62%	8.22%	Dec. 29, 1995
Class D Return After Taxes on Distributions	Class D Shares	Return After Taxes on Distributions		11.70%	5.99%	5.67%	4.96%	Dec. 29, 1995
Class D Return After Taxes on Distributions and Sale of Fund Shares	Class D Shares	Return After Taxes on Distributions and Sale of Fund Shares	[1]	9.30%	5.89%	5.60%	4.99%	Dec. 29, 1995
Barclays U.S. Corporate High-Yield Bond Index (reflects no deduction for expenses, fees, or taxes)		Barclays U.S. Corporate High-Yield Bond Index		15.81%	10.34%	10.62%	7.66%	Dec. 29, 1995

After-tax returns are calculated using distributions for the Fund’s Class D Shares for the periods following February 16, 2010; and for the Fund’s Class J Shares, the predecessor share class, for the periods prior to February 16, 2010. If Class D Shares of the Fund had been available during these earlier periods, distributions may have been different and thus, after-tax returns may have been different from those shown. After-tax returns are calculated using the historically highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes. Actual after-tax returns depend on your individual tax situation and may differ from those shown in the preceding table. The after-tax return information shown above does not apply to Fund shares held through a tax-deferred account, such as a 401(k) plan or an IRA.

[1] If the Fund incurs a loss, which generates a tax benefit, the Return After Taxes on Distributions and Sale of Fund Shares may exceed the Fund’s other return figures.

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Janus Short-Term Bond Fund | Class D Shares

FUND SUMMARY

Janus Short-Term Bond Fund

INVESTMENT OBJECTIVE

Janus Short-Term Bond Fund seeks as high a level of current income as is consistent with preservation of capital.

FEES AND EXPENSES OF THE FUND

This table describes the fees and expenses that you may pay if you buy and hold Shares of the Fund.

ANNUAL FUND OPERATING EXPENSES
(expenses that you pay each year as a percentage of the value of your investment)

Annual Fund Operating Expenses		Janus Short-Term Bond Fund Class D Shares Class D
Operating Expenses Column [Text]		Class D
Management Fees		0.55%
Other Expenses		0.22%
Total Annual Fund Operating Expenses	[1]	0.77%
Fee Waiver	[1]	0.15%
Total Annual Fund Operating Expenses After Fee Waiver	[1]	0.62%

EXAMPLE:

The following Example is based on expenses without waivers. The Example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds.

The Example assumes that you invest $10,000 in the Fund for the time periods indicated, reinvest all dividends and distributions, and then redeem all of your Shares at the end of each period. The Example also assumes that your investment has a 5% return each year and that the Fund’s operating expenses without waivers remain the same. Although your actual costs may be higher or lower, based on these assumptions your costs would be:

Expense Example (USD $)	Expense Example, By Year, Column [Text]	1 Year	3 Years	5 Years	10 Years
Janus Short-Term Bond Fund Class D Shares Class D	Class D Shares	79	246	428	954

Portfolio Turnover: 

The Fund pays transaction costs, such as commissions, when it buys and sells securities (or “turns over” its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when Fund shares are held in a taxable account. These costs, which are not reflected in annual fund operating expenses or in the Example, affect the Fund’s performance. During the most recent fiscal year, the Fund’s portfolio turnover rate was 100% of the average value of its portfolio.

PRINCIPAL INVESTMENT STRATEGIES

The Fund invests, under normal circumstances, at least 80% of its net assets in short- and intermediate-term securities such as corporate bonds or notes or government securities, including agency securities. The Fund may invest up to 35% of its net assets in high-yield/high-risk bonds, also known as “junk” bonds. The Fund expects to maintain an average-weighted effective maturity of three years or less under normal circumstances. As of June 30, 2013, the Fund’s weighted average maturity was 2.5 years. The Fund may also invest in bank loans, mortgage-backed securities, asset-backed securities, and foreign debt securities (which may include investments in emerging markets). Due to the nature of securities in which the Fund invests, it may have relatively high portfolio turnover compared to other funds.

“Effective” maturity differs from actual maturity, which may be longer. In calculating the “effective” maturity the portfolio managers will estimate the effect of expected principal payments and call provisions on securities held in the portfolio. This gives the portfolio managers some additional flexibility in the securities they purchase, but all else being equal, could result in more volatility than if the Fund calculated an actual maturity target.

In addition, the Fund may invest its assets in derivatives, which are instruments that have a value derived from, or directly linked to, an underlying asset, such as equity securities, fixed-income securities, commodities, currencies, interest rates, or market indices. In particular, the Fund may use derivatives to manage portfolio risk or to manage the effective maturity of the securities in the Fund’s portfolio. The Fund’s exposure to derivatives will vary. For purposes of meeting its 80% investment policy, the Fund may include derivatives that have characteristics similar to the securities in which the Fund may directly invest.

In addition to considering economic factors such as the effect of interest rates on the Fund’s investments, the portfolio managers apply a “bottom up” approach in choosing investments. This means that the portfolio managers look at income-producing securities one at a time to determine if a security is an attractive investment opportunity and if it is consistent with the Fund’s investment policies.

The Fund may lend portfolio securities on a short-term or long-term basis, in an amount equal to up to 1/3 of its total assets as determined at the time of the loan origination.

PRINCIPAL INVESTMENT RISKS

Although the Fund may be less volatile than funds that invest most of their assets in common stocks, the Fund’s returns and yields will vary, and you could lose money.

Fixed-Income Securities Risk. The Fund invests in a variety of fixed-income securities. Typically, the values of fixed-income securities change inversely with prevailing interest rates. Therefore, a fundamental risk of fixed-income securities is interest rate risk, which is the risk that the value of such securities will generally decline as prevailing interest rates rise, which may cause the Fund’s net asset value to likewise decrease. How specific fixed-income securities may react to changes in interest rates will depend on the specific characteristics of each security. Fixed-income securities are also subject to credit risk, prepayment risk, valuation risk, and liquidity risk. Credit risk is the risk that the credit strength of an issuer of a fixed-income security will weaken and/or that the issuer will be unable to make timely principal and interest payments and that the security may go into default. Prepayment risk is the risk that during periods of falling interest rates, certain fixed-income securities with higher interest rates, such as mortgage- and asset-backed securities, may be prepaid by their issuers thereby reducing the amount of interest payments. Valuation risk is the risk that one or more of the fixed-income securities in which the Fund invests are priced differently than the value realized upon such security’s sale. In times of market instability, valuation may be more difficult. Liquidity risk is the risk that fixed-income securities may be difficult or impossible to sell at the time that the portfolio managers would like or at the price the portfolio managers believe the security is currently worth.

Sovereign Debt Risk. The Fund may invest in U.S. and foreign government debt securities (“sovereign debt”). Investments in U.S. sovereign debt are considered low risk. However, investments in non-U.S. sovereign debt can involve a high degree of risk, including the risk that the governmental entity that controls the repayment of sovereign debt may not be willing or able to repay the principal and/or to pay the interest on its sovereign debt in a timely manner. A sovereign debtor’s willingness or ability to satisfy its debt obligation may be affected by various factors including, but not limited to, its cash flow situation, the extent of its foreign currency reserves, the availability of foreign exchange when a payment is due, and the relative size of its debt position in relation to its economy as a whole. In the event of default, there may be limited or no legal remedies for collecting sovereign debt and there may be no bankruptcy proceedings through which the Fund may collect all or part of the sovereign debt that a governmental entity has not repaid.

Foreign Exposure Risk. The Fund may have exposure to foreign markets as a result of its investments in foreign securities, including investments in emerging markets, which can be more volatile than the U.S. markets. As a result, its returns and net asset value may be affected to a large degree by fluctuations in currency exchange rates or political or economic conditions in a particular country. In some foreign markets, there may not be protection against failure by other parties to complete transactions. It may not be possible for the Fund to repatriate capital, dividends, interest, and other income from a particular country or governmental entity. In addition, a market swing in one or more countries or regions where the Fund has invested a significant amount of its assets may have a greater effect on the Fund’s performance than it would in a more geographically diversified portfolio. To the extent the Fund invests in foreign debt securities, such investments are sensitive to changes in interest rates. Additionally, investments in securities of foreign governments involve the risk that a foreign government may not be willing or able to pay interest or repay principal when due. The Fund’s investments in emerging market countries may involve risks greater than, or in addition to, the risks of investing in more developed countries.

Eurozone Risk. A number of countries in the European Union (“EU”) have experienced severe economic and financial difficulties. As a result, financial markets in the EU have been subject to extreme volatility and declines in asset values and liquidity. Responses to these financial problems by European governments, central banks, and others, including austerity measures and reforms, may not work, may result in social unrest, and may limit future growth and economic recovery or have other unintended consequences. Further defaults or restructurings by governments and others of their debt could have additional adverse effects on economies, financial markets, and asset valuations around the world. To the extent that the Fund has exposure to European markets or to transactions tied to the value of the euro, these events could negatively affect the value and liquidity of the Fund’s investments.

Mortgage-Backed Securities Risk. Mortgage-backed securities are classified generally as either commercial mortgage-backed securities or residential mortgage-backed securities, each of which is subject to certain specific risks. Mortgage-backed securities tend to be more sensitive to changes in interest rates than other types of debt securities. Investments in mortgage-backed securities are subject to both extension risk, where borrowers extend the duration of their mortgages in times of rising interest rates, and prepayment risk, where borrowers pay off their mortgages sooner than expected in times of declining interest rates. These risks may reduce the Fund’s returns. In addition, investments in mortgage-backed securities, including those comprised of subprime mortgages, may be subject to a higher degree of credit risk, valuation risk, and liquidity risk than various other types of fixed-income securities.

Bank Loan Risk. Bank loans are obligations of companies or other entities entered into in connection with recapitalizations, acquisitions, and refinancings. The Fund’s investments in bank loans are generally acquired as a participation interest in, or assignment of, loans originated by a lender or other financial institution. These investments may include institutionally-traded floating and fixed-rate debt securities. Participation interests and assignments involve credit, interest rate, and liquidity risk. In addition, the bank loans underlying these securities often involve borrowers with low credit ratings whose financial conditions are troubled or uncertain, including companies that are highly leveraged or in bankruptcy proceedings.

High-Yield/High-Risk Bond Risk. High-yield/high-risk bonds may be more sensitive than other types of bonds to economic changes, political changes, or adverse developments specific to the company that issued the bond, which may adversely affect their value.

Portfolio Turnover Risk. Increased portfolio turnover may result in higher costs, which may have a negative effect on the Fund’s performance. In addition, higher portfolio turnover may result in the acceleration of capital gains and the recognition of greater levels of short-term capital gains, which are taxed at ordinary federal income tax rates when distributed to shareholders.

Derivatives Risk. Derivatives can be highly volatile and involve risks in addition to the risks of the underlying referenced securities. Gains or losses from a derivative investment can be substantially greater than the derivative’s original cost, and can therefore involve leverage. Leverage may cause the Fund to be more volatile than if it had not used leverage. Derivatives can be less liquid than other types of investments and entail the risk that the counterparty will default on its payment obligations.

Securities Lending Risk. The Fund may seek to earn additional income through lending its securities to certain qualified broker-dealers and institutions. There is the risk that when portfolio securities are lent, the securities may not be returned on a timely basis, and the Fund may experience delays and costs in recovering the security or gaining access to the collateral provided to the Fund to collateralize the loan. If the Fund is unable to recover a security on loan, the Fund may use the collateral to purchase replacement securities in the market. There is a risk that the value of the collateral could decrease below the cost of the replacement security by the time the replacement investment is made, resulting in a loss to the Fund.

An investment in the Fund is not a bank deposit and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency.

PERFORMANCE INFORMATION

The following information provides some indication of the risks of investing in the Fund by showing how the Fund’s performance has varied over time. Class D Shares of the Fund commenced operations on February 16, 2010, as a result of the restructuring of Class J Shares, the predecessor share class. The performance shown for Class D Shares for periods prior to February 16, 2010, reflects the performance of the Fund’s former Class J Shares, calculated using the fees and expenses in effect during the periods shown, net of any applicable fee and expense limitations or waivers. If Class D Shares of the Fund had been available during periods prior to February 16, 2010, the performance shown may have been different. The performance shown for periods following the Fund’s commencement of Class D Shares reflects the fees and expenses of Class D Shares, net of any applicable fee and expense limitations or waivers.

The bar chart depicts the change in performance from year to year during the periods indicated. The table compares the Fund’s average annual returns for the periods indicated to a broad-based securities market index. The index is not actively managed and is not available for direct investment. All figures assume reinvestment of dividends and distributions. For certain periods, the Fund’s performance reflects the effect of expense waivers. Without the effect of these expense waivers, the performance shown would have been lower.

The Fund’s past performance (before and after taxes) does not necessarily indicate how it will perform in the future. Updated performance information is available at janus.com/allfunds or by calling 1-800-525-3713.

Annual Total Returns for Class D Shares (calendar year-end)

Best Quarter:  Second Quarter 2009  3.18%          Worst Quarter:  Second Quarter 2008  −0.90%

The Fund’s year-to-date return as of the calendar quarter ended September 30, 2013 was 0.79%.

Average Annual Total Returns (periods ended 12/31/12)

Average Annual Total Returns Janus Short-Term Bond Fund Class D Shares	Column	Label	1 Year	5 Years	10 Years	Since Inception	Inception Date
Class D Return Before Taxes	Class D Shares	Return Before Taxes	3.53%	4.31%	3.83%	4.60%	Sep. 01, 1992
Class D Return After Taxes on Distributions	Class D Shares	Return After Taxes on Distributions	2.72%	3.28%	2.69%	2.92%	Sep. 01, 1992
Class D Return After Taxes on Distributions and Sale of Fund Shares	Class D Shares	Return After Taxes on Distributions and Sale of Fund Shares	2.38%	3.10%	2.62%	2.89%	Sep. 01, 1992
Barclays 1-3 Year U.S. Government/Credit Index (reflects no deduction for expenses, fees, or taxes)		Barclays 1-3 Year U.S. Government/Credit Index	1.26%	2.88%	3.13%	4.62%	Sep. 01, 1992

After-tax returns are calculated using distributions for the Fund’s Class D Shares for the periods following February 16, 2010; and for the Fund’s Class J Shares, the predecessor share class, for the periods prior to February 16, 2010. If Class D Shares of the Fund had been available during these earlier periods, distributions may have been different and thus, after-tax returns may have been different from those shown. After-tax returns are calculated using the historically highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes. Actual after-tax returns depend on your individual tax situation and may differ from those shown in the preceding table. The after-tax return information shown above does not apply to Fund shares held through a tax-deferred account, such as a 401(k) plan or an IRA.

[1] Janus Capital has contractually agreed to waive its investment advisory fee and/or reimburse Fund expenses to the extent that the Fund’s total annual fund operating expenses (excluding administrative services fees payable pursuant to the Transfer Agency Agreement, brokerage commissions, interest, dividends, taxes, acquired fund fees and expenses, and extraordinary expenses) exceed 0.49% until at least November 1, 2014. The contractual waiver may be terminated or modified prior to this date only at the discretion of the Board of Trustees.

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INTECH International Fund | Class A, C, S, I, T Shares

FUND SUMMARY

INTECH International Fund

INVESTMENT OBJECTIVE

INTECH International Fund seeks long-term growth of capital.

FEES AND EXPENSES OF THE FUND

This table describes the fees and expenses that you may pay if you buy and hold Shares of the Fund. Each share class has different expenses, but represents an investment in the same Fund.

For Class A Shares, you may qualify for sales charge discounts if you and your family invest, or agree to invest in the future, at least $50,000 in the Fund or in other Janus mutual funds. More information about these and other discounts, as well as eligibility requirements for each share class, is available from your financial professional and in the “Purchases” section on page 51 of the Fund’s Prospectus and in the “Purchases” section on page 70 of the Fund’s Statement of Additional Information.

SHAREHOLDER FEES
(fees paid directly from your investment)

Shareholder Fees INTECH International Fund Class A, C, S, I, T Shares	Class A	Class C	Class S	Class I	Class T
Shareholder Fees Column [Text]	Class A	Class C	Class S	Class I	Class T
Maximum Sales Charge (load) Imposed on Purchases (as a percentage of offering price)	5.75%	none	none	none	none
Maximum Deferred Sales Charge (load) (as a percentage of the lower of original purchase price or redemption proceeds)	none	1.00%	none	none	none

ANNUAL FUND OPERATING EXPENSES
(expenses that you pay each year as a percentage of the value of your investment)

Annual Fund Operating Expenses INTECH International Fund Class A, C, S, I, T Shares		Class A	Class C	Class S	Class I	Class T
Operating Expenses Column [Text]		Class A	Class C	Class S	Class I	Class T
Management Fees		0.55%	0.55%	0.55%	0.55%	0.55%
Distribution/Service (12b-1) Fees		0.25%	1.00%	0.25%	none	none
Other Expenses		0.42%	0.60%	0.68%	0.37%	0.62%
Total Annual Fund Operating Expenses	[1]	1.22%	2.15%	1.48%	0.92%	1.17%
Fee Waiver	[1]	none	0.04%	none	none	none
Total Annual Fund Operating Expenses After Fee Waiver	[1]	1.22%	2.11%	1.48%	0.92%	1.17%

EXAMPLE:

The following Example is based on expenses without waivers. The Example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds.

The Example assumes that you invest $10,000 in the Fund for the time periods indicated and reinvest all dividends and distributions. The Example also assumes that your investment has a 5% return each year and that the Fund’s operating expenses without waivers remain the same. Although your actual costs may be higher or lower, based on these assumptions your costs would be:

If Shares are redeemed:

Expense Example INTECH International Fund Class A, C, S, I, T Shares (USD $)	Expense Example, By Year, Column [Text]	1 Year	3 Years	5 Years	10 Years
Class A	Class A Shares	692	940	1,207	1,967
Class C	Class C Shares	318	673	1,154	2,483
Class S	Class S Shares	151	468	808	1,768
Class I	Class I Shares	94	293	509	1,131
Class T	Class T Shares	119	372	644	1,420

If Shares are not redeemed:

Expense Example, No Redemption INTECH International Fund Class A, C, S, I, T Shares (USD $)	Expense Example, No Redemption, By Year, Column [Text]	1 Year	3 Years	5 Years	10 Years
Class A	Class A Shares	692	940	1,207	1,967
Class C	Class C Shares	218	673	1,154	2,483
Class S	Class S Shares	151	468	808	1,768
Class I	Class I Shares	94	293	509	1,131
Class T	Class T Shares	119	372	644	1,420

Portfolio Turnover: 

The Fund pays transaction costs, such as commissions, when it buys and sells securities (or “turns over” its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when Fund shares are held in a taxable account. These costs, which are not reflected in annual fund operating expenses or in the Example, affect the Fund’s performance. During the most recent fiscal year, the Fund’s portfolio turnover rate was 143% of the average value of its portfolio.

PRINCIPAL INVESTMENT STRATEGIES

The Fund invests primarily in common stocks from the universe of the Morgan Stanley Capital International (“MSCI”) EAFE^® (Europe, Australasia, Far East) Index, utilizing INTECH’s mathematical investment process. The MSCI EAFE^® Index is an MSCI index that is designed to measure the performance of the developed markets of Europe, Australasia, and the Far East. The Fund may also invest in foreign equity and debt securities.

The Fund pursues its investment objective by applying a mathematical investment process to construct an investment portfolio from the universe of common stocks within its named benchmark index. The goal of this process is to build a portfolio of stocks in a more efficient combination than the named benchmark index. The process seeks to capitalize on the natural volatility of the market by searching for stocks within the index that have high relative volatility (providing the potential for excess returns) but that essentially move in opposite directions or have low correlation to each other (providing the potential for lower relative risk). By constructing the portfolio in this manner and periodically rebalancing the portfolio to maintain potentially more efficient weightings, INTECH’s mathematical investment process seeks to create a portfolio that, over time, produces returns in excess of its named benchmark index with risks similar to that of the benchmark index. The rebalancing techniques used by INTECH may result in a higher portfolio turnover compared to a “buy and hold” fund strategy.

The Fund may lend portfolio securities on a short-term or long-term basis, in an amount equal to up to 1/3 of its total assets as determined at the time of the loan origination.

PRINCIPAL INVESTMENT RISKS

The biggest risk is that the Fund’s returns will vary, and you could lose money. The Fund is designed for long-term investors seeking an equity portfolio, including common stocks. Common stocks tend to be more volatile than many other investment choices.

Foreign Exposure Risk. The Fund normally has significant exposure to foreign markets as a result of its investments in foreign securities, which can be more volatile than the U.S. markets. As a result, its returns and net asset value may be affected to a large degree by fluctuations in currency exchange rates or political or economic conditions in a particular country. In some foreign markets, there may not be protection against failure by other parties to complete transactions. It may not be possible for the Fund to repatriate capital, dividends, interest, and other income from a particular country or governmental entity. In addition, a market swing in one or more countries or regions where the Fund has invested a significant amount of its assets may have a greater effect on the Fund’s performance than it would in a more geographically diversified portfolio.

Eurozone Risk. A number of countries in the European Union (“EU”) have experienced severe economic and financial difficulties. As a result, financial markets in the EU have been subject to extreme volatility and declines in asset values and liquidity. Responses to these financial problems by European governments, central banks, and others, including austerity measures and reforms, may not work, may result in social unrest, and may limit future growth and economic recovery or have other unintended consequences. Further defaults or restructurings by governments and others of their debt could have additional adverse effects on economies, financial markets, and asset valuations around the world. To the extent that the Fund has exposure to European markets or to transactions tied to the value of the euro, these events could negatively affect the value and liquidity of the Fund’s investments.

Market Risk. The value of the Fund’s portfolio may decrease if the value of an individual company or security, or multiple companies or securities, in the portfolio decreases. Further, regardless of how well individual companies or securities perform, the value of the Fund’s portfolio could also decrease if there are deteriorating economic or market conditions. It is important to understand that the value of your investment may fall, sometimes sharply, in response to changes in the market, and you could lose money.

Investment Process Risk. The proprietary mathematical investment process used by INTECH may not achieve the desired results. There is a risk that INTECH’s method of identifying stocks with higher volatility than the named benchmark index or its method of identifying stocks that tend to move in the same or opposite direction relative to each other (correlation) will not result in selecting stocks with continuing volatility or the expected correlation. In INTECH’s history, which spans more than 25 years, INTECH’s mathematical investment process has experienced periods of both underperformance and outperformance relative to an identified benchmark. Even when the proprietary mathematical investment process is working appropriately, INTECH expects that there will be periods of underperformance relative to the benchmark. On an occasional basis, INTECH makes changes to its mathematical investment process. These changes may result in changes to the portfolio, might not provide the intended results, and may adversely impact the Fund’s performance.

Real Estate Securities Risk. The Fund’s performance may be affected by the risks associated with investments in real estate-related companies. The value of real estate-related companies’ securities is sensitive to changes in real estate values and rental income, property taxes, interest rates, tax and regulatory requirements, supply and demand, and the management skill and creditworthiness of the company. Investments in real estate investment trusts (“REITs”) involve the same risks as other real estate investments. In addition, a REIT could fail to qualify for tax-free pass-through of its income under the Internal Revenue Code or fail to maintain its exemption from registration under the Investment Company Act of 1940, as amended, which could produce adverse economic consequences for the REIT and its investors, including the Fund.

Portfolio Turnover Risk. Increased portfolio turnover may result in higher costs, which may have a negative effect on the Fund’s performance. In addition, higher portfolio turnover may result in the acceleration of capital gains and the recognition of greater levels of short-term capital gains, which are taxed at ordinary federal income tax rates when distributed to shareholders.

Securities Lending Risk. The Fund may seek to earn additional income through lending its securities to certain qualified broker-dealers and institutions. There is the risk that when portfolio securities are lent, the securities may not be returned on a timely basis, and the Fund may experience delays and costs in recovering the security or gaining access to the collateral provided to the Fund to collateralize the loan. If the Fund is unable to recover a security on loan, the Fund may use the collateral to purchase replacement securities in the market. There is a risk that the value of the collateral could decrease below the cost of the replacement security by the time the replacement investment is made, resulting in a loss to the Fund.

An investment in the Fund is not a bank deposit and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency.

PERFORMANCE INFORMATION

The following information provides some indication of the risks of investing in the Fund by showing how the Fund’s performance has varied over time. Class I Shares, Class A Shares, Class C Shares, and Class S Shares of the Fund commenced operations on July 6, 2009, after the reorganization of each corresponding class of shares of Janus Adviser INTECH Risk-Managed International Fund (“JAD predecessor fund”) into each respective share class of the Fund. Class T Shares of the Fund commenced operations on July 6, 2009.

• The performance shown for Class I Shares, Class A Shares, Class C Shares, and Class S Shares for periods prior to July 6, 2009, reflects the historical performance of the JAD predecessor fund’s Class I Shares, Class A Shares, Class C Shares, and Class S Shares prior to the reorganization, calculated using the fees and expenses of each respective share class of the JAD predecessor fund, net of any applicable fee and expense limitations or waivers.
• The performance shown for Class T Shares for periods prior to July 6, 2009, reflects the historical performance of the JAD predecessor fund’s Class I Shares prior to the reorganization, calculated using the fees and expenses of Class T Shares, without the effect of any fee and expense limitations or waivers.

If Class T Shares of the Fund had been available during periods prior to July 6, 2009, the performance shown may have been different. The performance shown for periods following the Fund’s commencement of Class I Shares, Class A Shares, Class C Shares, Class S Shares, and Class T Shares reflects the fees and expenses of each respective share class, net of any applicable fee and expense limitations or waivers.

The bar chart depicts the change in performance from year to year during the periods indicated. The bar chart figures do not include any applicable sales charges that an investor may pay when they buy or sell Class A Shares or Class C Shares of the Fund. If sales charges were included, the returns would be lower. The table compares the Fund’s average annual returns for the periods indicated to a broad-based securities market index. The index is not actively managed and is not available for direct investment. All figures assume reinvestment of dividends and distributions. For certain periods, the Fund’s performance reflects the effect of expense waivers. Without the effect of these expense waivers, the performance shown would have been lower.

The Fund’s past performance (before and after taxes) does not necessarily indicate how it will perform in the future. Updated performance information is available at janus.com/advisor/mutual-funds or by calling 1-877-335-2687.

Annual Total Returns for Class I Shares (calendar year-end)

Best Quarter:  Second Quarter 2009  22.50%          Worst Quarter:  Third Quarter 2008  −20.70%

The Fund’s year-to-date return as of the calendar quarter ended September 30, 2013 was 18.27%.

Average Annual Total Returns (periods ended 12/31/12)

Average Annual Total Returns INTECH International Fund Class A, C, S, I, T Shares	Column	Label		1 Year	5 Years	Since Inception of Predecessor Fund	Inception Date
Class I Return Before Taxes	Class I Shares	Return Before Taxes		17.03%	(4.06%)	(2.88%)	May 02, 2007
Class I Return After Taxes on Distributions	Class I Shares	Return After Taxes on Distributions		16.65%	(4.20%)	(3.06%)	May 02, 2007
Class I Return After Taxes on Distributions and Sale of Fund Shares	Class I Shares	Return After Taxes on Distributions and Sale of Fund Shares	[1]	11.76%	(3.29%)	(2.32%)	May 02, 2007
Class A Return Before Taxes	Class A Shares	Return Before Taxes	[2]	10.06%	(5.23%)	(3.95%)	May 02, 2007
Class C Return Before Taxes	Class C Shares	Return Before Taxes	[3]	15.43%	(4.31%)	(3.22%)	May 02, 2007
Class S Return Before Taxes	Class S Shares	Return Before Taxes		16.48%	(4.18%)	(3.04%)	May 02, 2007
Class T Return Before Taxes	Class T Shares	Return Before Taxes		16.70%	(5.11%)	(4.20%)	May 02, 2007
Morgan Stanley Capital International EAFE® Index (net of foreign withholding taxes) (reflects no deduction for expenses, fees, or taxes, except foreign withholding taxes)		Morgan Stanley Capital International EAFE® Index (net of foreign withholding taxes)		17.32%	(3.69%)	(2.89%)	May 02, 2007

After-tax returns are calculated using distributions for the Fund’s Class I Shares for periods following July 6, 2009; and for the JAD predecessor fund’s Class I Shares for periods prior to July 6, 2009. After-tax returns are calculated using the historically highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes. Actual after-tax returns depend on your individual tax situation and may differ from those shown in the preceding table. The after-tax return information shown above does not apply to Fund shares held through a tax-deferred account, such as a 401(k) plan or an IRA.

After-tax returns are only shown for Class I Shares of the Fund. After-tax returns for the other classes of Shares will vary from those shown for Class I Shares due to varying sales charges (as applicable), fees, and expenses among the classes.

[1] Janus Capital has contractually agreed to waive its investment advisory fee and/or reimburse Fund expenses to the extent that the Fund’s total annual fund operating expenses (excluding the distribution and shareholder servicing fees – applicable to Class A Shares, Class C Shares, and Class S Shares; administrative services fees payable pursuant to the Transfer Agency Agreement; brokerage commissions; interest; dividends; taxes; acquired fund fees and expenses; and extraordinary expenses) exceed 1.00% until at least November 1, 2014. The contractual waiver may be terminated or modified prior to this date only at the discretion of the Board of Trustees.

[1] If the Fund incurs a loss, which generates a tax benefit, the Return After Taxes on Distributions and Sale of Fund Shares may exceed the Fund’s other return figures.

[2] Calculated assuming maximum permitted sales loads.

[3] The one year return is calculated to include the contingent deferred sales charge.

XML

Label	Element	Value
Risk/Return:	rr_RiskReturnAbstract
Registrant Name	dei_EntityRegistrantName	JANUS INVESTMENT FUND
Prospectus Date	rr_ProspectusDate	Oct. 28, 2013
Perkins Value Plus Income Fund | Class D Shares
Risk/Return:	rr_RiskReturnAbstract
Risk/Return [Heading]	rr_RiskReturnHeading	FUND SUMMARY Perkins Value Plus Income Fund
Objective [Heading]	rr_ObjectiveHeading	INVESTMENT OBJECTIVE
Objective, Primary [Text Block]	rr_ObjectivePrimaryTextBlock	Perkins Value Plus Income Fund seeks capital appreciation and current income.
Expense [Heading]	rr_ExpenseHeading	FEES AND EXPENSES OF THE FUND
Expense Narrative [Text Block]	rr_ExpenseNarrativeTextBlock	This table describes the fees and expenses that you may pay if you buy and hold Shares of the Fund.
Operating Expenses Caption [Text]	rr_OperatingExpensesCaption	ANNUAL FUND OPERATING EXPENSES (expenses that you pay each year as a percentage of the value of your investment)
Fee Waiver or Reimbursement over Assets, Date of Termination	rr_FeeWaiverOrReimbursementOverAssetsDateOfTermination	November 1, 2014
Portfolio Turnover [Heading]	rr_PortfolioTurnoverHeading	Portfolio Turnover:
Portfolio Turnover [Text Block]	rr_PortfolioTurnoverTextBlock	The Fund pays transaction costs, such as commissions, when it buys and sells securities (or “turns over” its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when Fund shares are held in a taxable account. These costs, which are not reflected in annual fund operating expenses or in the Example, affect the Fund’s performance. During the most recent fiscal year, the Fund’s portfolio turnover rate was 97% of the average value of its portfolio.
Portfolio Turnover, Rate	rr_PortfolioTurnoverRate	97.00%
Expense Example [Heading]	rr_ExpenseExampleHeading	EXAMPLE:
Expense Example by Year [Heading]	rr_ExpenseExampleByYearHeading	The Example assumes that you invest $10,000 in the Fund for the time periods indicated, reinvest all dividends and distributions, and then redeem all of your Shares at the end of each period. The Example also assumes that your investment has a 5% return each year and that the Fund’s operating expenses without waivers or recoupments (if applicable) remain the same. Although your actual costs may be higher or lower, based on these assumptions your costs would be:
Expense Example Narrative [Text Block]	rr_ExpenseExampleNarrativeTextBlock	The following Example is based on expenses without waivers. The Example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds.
Strategy [Heading]	rr_StrategyHeading	PRINCIPAL INVESTMENT STRATEGIES
Strategy Narrative [Text Block]	rr_StrategyNarrativeTextBlock	The Fund pursues its investment objective by normally investing 40-60% of its assets in equity securities selected primarily for capital appreciation and investing the remainder in fixed-income securities and cash equivalents. Equity Securities. The Fund’s equity investments generate total return from a combination of capital appreciation and, to a lesser degree, current income. Such equity investments may include companies of any size, but the Fund will invest primarily in large- and mid-sized companies whose stock prices the portfolio managers believe to be undervalued or have the potential for high relative dividend yields, or both. The Fund’s equity portfolio managers invest in companies which have fallen out of favor with the market or that appear to be temporarily misunderstood by the investment community. The Fund’s equity portfolio managers generally look for companies with: strong balance sheets and solid recurring free cash flows attractive relative and absolute valuation ratios or that have underperformed recently favorable reward to risk characteristics Fixed-Income Securities. The Fund’s fixed-income investments generate total return from a combination of current income and capital appreciation, but income is usually the dominant portion. The Fund normally invests the portion of its assets allocated to fixed-income investments in debt securities (including, but not limited to, government bonds, corporate bonds, mortgage-backed securities, asset-backed securities, zero-coupon bonds, and bank loans), convertible securities, and short-term securities. The Fund invests at least 50% of the fixed-income portion of its assets in investment grade debt securities. The Fund will limit its investment in high-yield/high-risk bonds, also known as “junk” bonds, to 50% or less of the fixed-income portion of its net assets. In addition to considering economic factors such as the effect of interest rates on the Fund’s fixed-income investments, the Fund’s fixed-income portfolio managers apply a “bottom up” approach in choosing investments. This means that the portfolio managers look at income-producing securities one at a time to determine if a security is an attractive investment opportunity and if it is consistent with the Fund’s investment policies. The Fund may also invest in foreign equity and debt securities, which may include investments in emerging markets. The Fund may also invest its assets in derivatives, which are instruments that have a value derived from, or directly linked to, an underlying asset, such as equity securities, fixed-income securities, commodities, currencies, interest rates, or market indices. The Fund has and is expected to continue to buy and sell put and call options to enhance returns. The Fund’s exposure to derivatives will vary, is not limited to those derivatives listed, and could be significant at times. Janus Capital is primarily responsible for the overall asset allocation of the Fund and manages the Fund’s fixed-income investments. Cash positions are considered a part of the Fund’s fixed-income allocation and will be managed by the Fund’s fixed-income portfolio managers. Perkins manages the Fund’s equity investments and assists the adviser in determining the Fund’s overall asset allocation. The Fund may periodically adjust its mix of equity and fixed-income investments in response to changing economic and market conditions, including outside the range of 40-60% of its assets in equity securities. Due to the nature of the fixed-income securities in which the Fund invests, it may have relatively high portfolio turnover compared to other funds. The Fund’s fixed-income portfolio managers may lend portfolio securities on a short-term or long-term basis, in an amount equal to up to 1/3 of its total assets as determined at the time of the loan origination.
Risk [Heading]	rr_RiskHeading	PRINCIPAL INVESTMENT RISKS
Risk Narrative [Text Block]	rr_RiskNarrativeTextBlock	The biggest risk is that the Fund’s returns and yields will vary, and you could lose money. The Fund is designed for long-term investors seeking a portfolio including common stocks and bonds selected for their potential to produce capital appreciation and current income. Common stocks tend to be more volatile than many other investment choices. Market Risk. The value of the Fund’s portfolio may decrease if the value of an individual company or security, or multiple companies or securities, in the portfolio decreases or if the portfolio managers’ belief about a company’s intrinsic worth is incorrect. Further, regardless of how well individual companies or securities perform, the value of the Fund’s portfolio could also decrease if there are deteriorating economic or market conditions. It is important to understand that the value of your investment may fall, sometimes sharply, in response to changes in the market, and you could lose money. Value Investing Risk. Because different types of stocks tend to shift in and out of favor depending on market and economic conditions, “value” stocks may perform differently than other types of stocks and from the market as a whole, and can continue to be undervalued by the market for long periods of time. It is also possible that a value stock will never appreciate to the extent expected by the equity portfolio managers. Mid-Sized Companies Risk. The Fund’s investments in securities issued by mid-sized companies may involve greater risks than are customarily associated with larger, more established companies. Securities issued by mid-sized companies tend to be more volatile than securities issued by larger or more established companies and may underperform as compared to the securities of larger companies. Fixed-Income Securities Risk. The Fund invests in a variety of fixed-income securities. Typically, the values of fixed-income securities change inversely with prevailing interest rates. Therefore, a fundamental risk of fixed-income securities is interest rate risk, which is the risk that the value of such securities will generally decline as prevailing interest rates rise, which may cause the Fund’s net asset value to likewise decrease. How specific fixed-income securities may react to changes in interest rates will depend on the specific characteristics of each security. Fixed-income securities are also subject to credit risk, prepayment risk, valuation risk, and liquidity risk. Credit risk is the risk that the credit strength of an issuer of a fixed-income security will weaken and/or that the issuer will be unable to make timely principal and interest payments and that the security may go into default. Prepayment risk is the risk that during periods of falling interest rates, certain fixed-income securities with higher interest rates, such as mortgage- and asset-backed securities, may be prepaid by their issuers thereby reducing the amount of interest payments. Valuation risk is the risk that one or more of the fixed-income securities in which the Fund invests are priced differently than the value realized upon such security’s sale. In times of market instability, valuation may be more difficult. Liquidity risk is the risk that fixed-income securities may be difficult or impossible to sell at the time that the portfolio managers would like or at the price the portfolio managers believe the security is currently worth. Mortgage-Backed Securities Risk. Mortgage-backed securities are classified generally as either commercial mortgage-backed securities or residential mortgage-backed securities, each of which is subject to certain specific risks. Mortgage-backed securities tend to be more sensitive to changes in interest rates than other types of debt securities. Investments in mortgage-backed securities are subject to both extension risk, where borrowers extend the duration of their mortgages in times of rising interest rates, and prepayment risk, where borrowers pay off their mortgages sooner than expected in times of declining interest rates. These risks may reduce the Fund’s returns. In addition, investments in mortgage-backed securities, including those comprised of subprime mortgages, may be subject to a higher degree of credit risk, valuation risk, and liquidity risk than various other types of fixed-income securities. High-Yield/High-Risk Bond Risk. High-yield/high-risk bonds may be more sensitive than other types of bonds to economic changes, political changes, or adverse developments specific to the company that issued the bond, which may adversely affect their value. Bank Loan Risk. Bank loans are obligations of companies or other entities entered into in connection with recapitalizations, acquisitions, and refinancings. The Fund’s investments in bank loans are generally acquired as a participation interest in, or assignment of, loans originated by a lender or other financial institution. These investments may include institutionally-traded floating and fixed-rate debt securities. Participation interests and assignments involve credit, interest rate, and liquidity risk. In addition, the bank loans underlying these securities often involve borrowers with low credit ratings whose financial conditions are troubled or uncertain, including companies that are highly leveraged or in bankruptcy proceedings. Foreign Exposure Risk. The Fund may have exposure to foreign markets as a result of its investments in foreign securities, including investments in emerging markets, which can be more volatile than the U.S. markets. As a result, its returns and net asset value may be affected to a large degree by fluctuations in currency exchange rates or political or economic conditions in a particular country. In some foreign markets, there may not be protection against failure by other parties to complete transactions. It may not be possible for the Fund to repatriate capital, dividends, interest, and other income from a particular country or governmental entity. In addition, a market swing in one or more countries or regions where the Fund has invested a significant amount of its assets may have a greater effect on the Fund’s performance than it would in a more geographically diversified portfolio. To the extent the Fund invests in foreign debt securities, such investments are sensitive to changes in interest rates. Additionally, investments in securities of foreign governments involve the risk that a foreign government may not be willing or able to pay interest or repay principal when due. The Fund’s investments in emerging market countries may involve risks greater than, or in addition to, the risks of investing in more developed countries. Eurozone Risk. A number of countries in the European Union (“EU”) have experienced severe economic and financial difficulties. As a result, financial markets in the EU have been subject to extreme volatility and declines in asset values and liquidity. Responses to these financial problems by European governments, central banks, and others, including austerity measures and reforms, may not work, may result in social unrest, and may limit future growth and economic recovery or have other unintended consequences. Further defaults or restructurings by governments and others of their debt could have additional adverse effects on economies, financial markets, and asset valuations around the world. To the extent that the Fund has exposure to European markets or to transactions tied to the value of the euro, these events could negatively affect the value and liquidity of the Fund’s investments. Sovereign Debt Risk. The Fund may invest in U.S. and foreign government debt securities (“sovereign debt”). Investments in U.S. sovereign debt are considered low risk. However, investments in non-U.S. sovereign debt can involve a high degree of risk, including the risk that the governmental entity that controls the repayment of sovereign debt may not be willing or able to repay the principal and/or to pay the interest on its sovereign debt in a timely manner. A sovereign debtor’s willingness or ability to satisfy its debt obligation may be affected by various factors including, but not limited to, its cash flow situation, the extent of its foreign currency reserves, the availability of foreign exchange when a payment is due, and the relative size of its debt position in relation to its economy as a whole. In the event of default, there may be limited or no legal remedies for collecting sovereign debt and there may be no bankruptcy proceedings through which the Fund may collect all or part of the sovereign debt that a governmental entity has not repaid. Real Estate Securities Risk. The Fund’s performance may be affected by the risks associated with investments in real estate-related companies. The value of real estate-related companies’ securities is sensitive to changes in real estate values and rental income, property taxes, interest rates, tax and regulatory requirements, supply and demand, and the management skill and creditworthiness of the company. Investments in real estate investment trusts (“REITs”) involve the same risks as other real estate investments. In addition, a REIT could fail to qualify for tax-free pass-through of its income under the Internal Revenue Code or fail to maintain its exemption from registration under the Investment Company Act of 1940, as amended, which could produce adverse economic consequences for the REIT and its investors, including the Fund. Derivatives Risk. Derivatives can be highly volatile and involve risks in addition to the risks of the underlying referenced securities. Gains or losses from a derivative investment can be substantially greater than the derivative’s original cost, and can therefore involve leverage. Leverage may cause the Fund to be more volatile than if it had not used leverage. Derivatives can be complex instruments and may involve analysis that differs from that required for other investment types used by the Fund. If the value of a derivative does not correlate well with the particular market or other asset class to which the derivative is intended to provide exposure, the derivative may not produce the anticipated result. Derivatives can also reduce the opportunity for gain or result in losses by offsetting positive returns in other investments. Derivatives can be less liquid than other types of investments and entail the risk that the counterparty will default on its payment obligations. If the counterparty to a derivative transaction defaults, the Fund would risk the loss of the net amount of the payments that it contractually is entitled to receive. To the extent the Fund enters into short derivative positions, the Fund may be exposed to risks similar to those associated with short sales, including the risk that the Fund’s losses are theoretically unlimited. Allocation Risk. The Fund’s ability to achieve its investment objective depends largely upon the allocation of assets among the equity and fixed asset categories. You could lose money on your investment in the Fund as a result of these allocations. Portfolio management may favor an asset category that underperforms relative to other asset categories. For example, the Fund may be overweighted in equity securities when the stock market is falling and the fixed-income market is rising. Additionally, periodic rebalancing of Fund assets among asset categories may result in increased transaction costs, which may have a negative effect on the Fund’s performance. Portfolio Turnover Risk. Increased portfolio turnover may result in higher costs, which may have a negative effect on the Fund’s performance. In addition, higher portfolio turnover may result in the acceleration of capital gains and the recognition of greater levels of short-term capital gains, which are taxed at ordinary federal income tax rates when distributed to shareholders. Securities Lending Risk. The Fund’s fixed-income portfolio managers may seek to earn additional income through lending its securities to certain qualified broker-dealers and institutions. There is the risk that when portfolio securities are lent, the securities may not be returned on a timely basis, and the Fund may experience delays and costs in recovering the security or gaining access to the collateral provided to the Fund to collateralize the loan. If the Fund is unable to recover a security on loan, the Fund may use the collateral to purchase replacement securities in the market. There is a risk that the value of the collateral could decrease below the cost of the replacement security by the time the replacement investment is made, resulting in a loss to the Fund. An investment in the Fund is not a bank deposit and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency.
Risk Lose Money [Text]	rr_RiskLoseMoney	The biggest risk is that the Fund’s returns and yields will vary, and you could lose money.
Risk Not Insured Depository Institution [Text]	rr_RiskNotInsuredDepositoryInstitution	An investment in the Fund is not a bank deposit and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency.
Bar Chart and Performance Table [Heading]	rr_BarChartAndPerformanceTableHeading	PERFORMANCE INFORMATION
Performance Narrative [Text Block]	rr_PerformanceNarrativeTextBlock	The following information provides some indication of the risks of investing in the Fund by showing how the Fund’s performance has varied over time. The bar chart depicts the change in performance from year to year during the periods indicated. The table compares the Fund’s average annual returns for the periods indicated to broad-based securities market indices. The indices are not actively managed and are not available for direct investment. All figures assume reinvestment of dividends and distributions. For certain periods, the Fund’s performance reflects the effect of expense waivers. Without the effect of these expense waivers, the performance shown would have been lower. The Fund’s past performance (before and after taxes) does not necessarily indicate how it will perform in the future. Updated performance information is available at janus.com/allfunds or by calling 1-800-525-3713.
Performance Information Illustrates Variability of Returns [Text]	rr_PerformanceInformationIllustratesVariabilityOfReturns	The following information provides some indication of the risks of investing in the Fund by showing how the Fund’s performance has varied over time. The bar chart depicts the change in performance from year to year during the periods indicated.
Performance Additional Market Index [Text]	rr_PerformanceAdditionalMarketIndex	The table compares the Fund’s average annual returns for the periods indicated to broad-based securities market indices. The indices are not actively managed and are not available for direct investment. All figures assume reinvestment of dividends and distributions.
Performance Availability Phone [Text]	rr_PerformanceAvailabilityPhone	1-800-525-3713
Performance Availability Website Address [Text]	rr_PerformanceAvailabilityWebSiteAddress	janus.com/allfunds
Performance Past Does Not Indicate Future [Text]	rr_PerformancePastDoesNotIndicateFuture	The Fund’s past performance (before and after taxes) does not necessarily indicate how it will perform in the future.
Bar Chart [Heading]	rr_BarChartHeading	Annual Total Returns for Class D Shares (calendar year-end)
Bar Chart Closing [Text Block]	rr_BarChartClosingTextBlock	Best Quarter:  Fourth Quarter 2011  7.30%          Worst Quarter:  Third Quarter 2011  −7.84%
Year to Date Return, Label	rr_YearToDateReturnLabel	The Fund’s year-to-date return as of the calendar quarter ended September 30, 2013 was 8.96%.
Performance Table Heading	rr_PerformanceTableHeading	Average Annual Total Returns (periods ended 12/31/12)
Performance Table Uses Highest Federal Rate	rr_PerformanceTableUsesHighestFederalRate	After-tax returns are calculated using the historically highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes.
Performance Table Not Relevant to Tax Deferred	rr_PerformanceTableNotRelevantToTaxDeferred	Actual after-tax returns depend on your individual tax situation and may differ from those shown in the preceding table. The after-tax return information shown above does not apply to Fund shares held through a tax-deferred account, such as a 401(k) plan or an IRA.
Performance Table Narrative	rr_PerformanceTableNarrativeTextBlock	The Value Income Index is an internally-calculated, hypothetical combination of unmanaged indices that combines total returns from the Russell 1000® Value Index (50%) and the Barclays U.S. Aggregate Bond Index (50%). After-tax returns are calculated using the historically highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes. Actual after-tax returns depend on your individual tax situation and may differ from those shown in the preceding table. The after-tax return information shown above does not apply to Fund shares held through a tax-deferred account, such as a 401(k) plan or an IRA.
Performance Table Closing [Text Block]	rr_PerformanceTableClosingTextBlock	Updated performance information is available at janus.com/allfunds or by calling 1-800-525-3713.
Perkins Value Plus Income Fund | Class D Shares | Class D
Risk/Return:	rr_RiskReturnAbstract
Operating Expenses Column [Text]	rr_OperatingExpensesColumnName	Class D
Management Fees	rr_ManagementFeesOverAssets	0.60%
Other Expenses	rr_OtherExpensesOverAssets	0.64%
Total Annual Fund Operating Expenses	rr_ExpensesOverAssets	1.24%	[1]
Fee Waiver	rr_FeeWaiverOrReimbursementOverAssets	0.43%	[1]
Total Annual Fund Operating Expenses After Fee Waiver	rr_NetExpensesOverAssets	0.81%	[1]
Expense Example, By Year, Column [Text]	rr_ExpenseExampleByYearColumnName	Class D Shares
1 Year	rr_ExpenseExampleYear01	$ 126
3 Years	rr_ExpenseExampleYear03	393
5 Years	rr_ExpenseExampleYear05	681
10 Years	rr_ExpenseExampleYear10	$ 1,500
2011	rr_AnnualReturn2011	3.66%
2012	rr_AnnualReturn2012	11.56%
Bar Chart, Year to Date Return, Date	rr_BarChartYearToDateReturnDate	Sep. 30, 2013
Bar Chart, Year to Date Return	rr_BarChartYearToDateReturn	8.96%
Highest Quarterly Return, Label	rr_HighestQuarterlyReturnLabel	Best Quarter:
Highest Quarterly Return, Date	rr_BarChartHighestQuarterlyReturnDate	Dec. 31, 2011
Highest Quarterly Return	rr_BarChartHighestQuarterlyReturn	7.30%
Lowest Quarterly Return, Label	rr_LowestQuarterlyReturnLabel	Worst Quarter:
Lowest Quarterly Return, Date	rr_BarChartLowestQuarterlyReturnDate	Sep. 30, 2011
Lowest Quarterly Return	rr_BarChartLowestQuarterlyReturn	(7.84%)
Perkins Value Plus Income Fund | Class D Shares | Return Before Taxes | Class D
Risk/Return:	rr_RiskReturnAbstract
Column	rr_AverageAnnualReturnColumnName	Class D Shares
Label	rr_AverageAnnualReturnLabel	Return Before Taxes
1 Year	rr_AverageAnnualReturnYear01	11.56%
Since Inception	rr_AverageAnnualReturnSinceInception	10.17%
Inception Date	rr_AverageAnnualReturnInceptionDate	Jul. 30, 2010
Perkins Value Plus Income Fund | Class D Shares | Return After Taxes on Distributions | Class D
Risk/Return:	rr_RiskReturnAbstract
Column	rr_AverageAnnualReturnColumnName	Class D Shares
Label	rr_AverageAnnualReturnLabel	Return After Taxes on Distributions
1 Year	rr_AverageAnnualReturnYear01	10.15%
Since Inception	rr_AverageAnnualReturnSinceInception	8.52%
Inception Date	rr_AverageAnnualReturnInceptionDate	Jul. 30, 2010
Perkins Value Plus Income Fund | Class D Shares | Return After Taxes on Distributions and Sale of Fund Shares | Class D
Risk/Return:	rr_RiskReturnAbstract
Column	rr_AverageAnnualReturnColumnName	Class D Shares
Label	rr_AverageAnnualReturnLabel	Return After Taxes on Distributions and Sale of Fund Shares
1 Year	rr_AverageAnnualReturnYear01	8.07%
Since Inception	rr_AverageAnnualReturnSinceInception	7.90%
Inception Date	rr_AverageAnnualReturnInceptionDate	Jul. 30, 2010
Perkins Value Plus Income Fund | Class D Shares | Russell 1000® Value Index (reflects no deduction for expenses, fees, or taxes)
Risk/Return:	rr_RiskReturnAbstract
Label	rr_AverageAnnualReturnLabel	Russell 1000® Value Index
1 Year	rr_AverageAnnualReturnYear01	17.51%
Since Inception	rr_AverageAnnualReturnSinceInception	13.02%
Inception Date	rr_AverageAnnualReturnInceptionDate	Jul. 30, 2010
Perkins Value Plus Income Fund | Class D Shares | Barclays U.S. Aggregate Bond Index (reflects no deduction for expenses, fees, or taxes)
Risk/Return:	rr_RiskReturnAbstract
Label	rr_AverageAnnualReturnLabel	Barclays U.S. Aggregate Bond Index
1 Year	rr_AverageAnnualReturnYear01	4.21%
Since Inception	rr_AverageAnnualReturnSinceInception	4.97%
Inception Date	rr_AverageAnnualReturnInceptionDate	Jul. 30, 2010
Perkins Value Plus Income Fund | Class D Shares | Value Income Index (reflects no deduction for expenses, fees, or taxes)
Risk/Return:	rr_RiskReturnAbstract
Label	rr_AverageAnnualReturnLabel	Value Income Index
1 Year	rr_AverageAnnualReturnYear01	10.84%
Since Inception	rr_AverageAnnualReturnSinceInception	9.26%
Inception Date	rr_AverageAnnualReturnInceptionDate	Jul. 30, 2010

[1] Janus Capital has contractually agreed to waive its investment advisory fee and/or reimburse Fund expenses to the extent that the Fund’s total annual fund operating expenses (excluding administrative services fees payable pursuant to the Transfer Agency Agreement, brokerage commissions, interest, dividends, taxes, acquired fund fees and expenses, and extraordinary expenses) exceed 0.68% until at least November 1, 2014. The contractual waiver may be terminated or modified prior to this date only at the discretion of the Board of Trustees. For a period of three years subsequent to the Fund’s commencement of operations (July 30, 2010), Janus Capital may recover from the Fund fees and expenses previously waived or reimbursed, which could then be considered a deferral, if the Fund’s expense ratio, including recovered expenses, falls below the expense limit.

XML

Label	Element	Value
Risk/Return:	rr_RiskReturnAbstract
Registrant Name	dei_EntityRegistrantName	JANUS INVESTMENT FUND
Prospectus Date	rr_ProspectusDate	Oct. 28, 2013
Perkins Large Cap Value Fund | Class A, C, S, I, N, T Shares
Risk/Return:	rr_RiskReturnAbstract
Risk/Return [Heading]	rr_RiskReturnHeading	FUND SUMMARY Perkins Large Cap Value Fund
Objective [Heading]	rr_ObjectiveHeading	INVESTMENT OBJECTIVE
Objective, Primary [Text Block]	rr_ObjectivePrimaryTextBlock	Perkins Large Cap Value Fund seeks capital appreciation.
Expense [Heading]	rr_ExpenseHeading	FEES AND EXPENSES OF THE FUND
Expense Narrative [Text Block]	rr_ExpenseNarrativeTextBlock	This table describes the fees and expenses that you may pay if you buy and hold Shares of the Fund. Each share class has different expenses, but represents an investment in the same Fund.
Shareholder Fees Caption [Text]	rr_ShareholderFeesCaption	SHAREHOLDER FEES (fees paid directly from your investment)
Operating Expenses Caption [Text]	rr_OperatingExpensesCaption	ANNUAL FUND OPERATING EXPENSES (expenses that you pay each year as a percentage of the value of your investment)
Fee Waiver or Reimbursement over Assets, Date of Termination	rr_FeeWaiverOrReimbursementOverAssetsDateOfTermination	November 1, 2014
Portfolio Turnover [Heading]	rr_PortfolioTurnoverHeading	Portfolio Turnover:
Portfolio Turnover [Text Block]	rr_PortfolioTurnoverTextBlock	The Fund pays transaction costs, such as commissions, when it buys and sells securities (or “turns over” its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when Fund shares are held in a taxable account. These costs, which are not reflected in annual fund operating expenses or in the Example, affect the Fund’s performance. During the most recent fiscal year, the Fund’s portfolio turnover rate was 45% of the average value of its portfolio.
Portfolio Turnover, Rate	rr_PortfolioTurnoverRate	45.00%
Expense Breakpoint Discounts [Text]	rr_ExpenseBreakpointDiscounts	For Class A Shares, you may qualify for sales charge discounts if you and your family invest, or agree to invest in the future, at least $50,000 in the Fund or in other Janus mutual funds. More information about these and other discounts, as well as eligibility requirements for each share class, is available from your financial professional and in the “Purchases” section on page 66 of the Fund’s Prospectus and in the “Purchases” section on page 70 of the Fund’s Statement of Additional Information.
Expense Breakpoint, Minimum Investment Required [Amount]	rr_ExpenseBreakpointMinimumInvestmentRequiredAmount	$ 50,000
Expense Example [Heading]	rr_ExpenseExampleHeading	EXAMPLE:
Expense Example by Year [Heading]	rr_ExpenseExampleByYearHeading	The Example assumes that you invest $10,000 in the Fund for the time periods indicated and reinvest all dividends and distributions. The Example also assumes that your investment has a 5% return each year and that the Fund’s operating expenses without waivers remain the same. Although your actual costs may be higher or lower, based on these assumptions your costs would be:
Expense Example Narrative [Text Block]	rr_ExpenseExampleNarrativeTextBlock	The following Example is based on expenses without waivers. The Example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds.
Expense Example by, Year, Caption [Text]	rr_ExpenseExampleByYearCaption	If Shares are redeemed:
Expense Example, No Redemption, By Year, Caption [Text]	rr_ExpenseExampleNoRedemptionByYearCaption	If Shares are not redeemed:
Strategy [Heading]	rr_StrategyHeading	PRINCIPAL INVESTMENT STRATEGIES
Strategy Narrative [Text Block]	rr_StrategyNarrativeTextBlock	The Fund pursues its investment objective by investing primarily in common stocks selected for their capital appreciation potential. The Fund primarily invests in the common stocks of large-sized companies whose stock prices the portfolio managers believe to be undervalued. The Fund invests, under normal circumstances, at least 80% of its net assets in equity securities of companies having, at the time of purchase, market capitalizations equal to or greater than the median market capitalization of companies included in the Russell 1000® Value Index. The market capitalizations within the index will vary, but as of June 30, 2013, they ranged from approximately $487 million to $422.5 billion, and the median market capitalization was $5.9 billion. The Fund may also invest in foreign equity and debt securities, which may include investments in emerging markets. The Fund may invest, under normal circumstances, up to 20% of its net assets in securities of companies having market capitalizations outside of the aforementioned market capitalization ranges. In addition, when the portfolio managers believe that market conditions are unfavorable for investing, or when they are otherwise unable to locate attractive investment opportunities, the Fund may invest up to 20% of its net assets in exchange-traded funds ("ETFs"), including commodity-related ETFs, cash, or similar investments. The Fund focuses on companies that have fallen out of favor with the market or that appear to be temporarily misunderstood by the investment community. The Fund's portfolio managers generally look for companies with: strong balance sheets and solid recurring free cash flows attractive relative and absolute valuation ratios or that have underperformed recently favorable reward to risk characteristics The Fund may invest its assets in derivatives, which are instruments that have a value derived from, or directly linked to, an underlying asset, such as equity securities, fixed-income securities, commodities, currencies, interest rates, or market indices, as substitutes for securities in which the Fund invests. The Fund may invest in derivative instruments (by taking long and/or short positions) for different purposes, including hedging (to offset risks associated with an investment, currency exposure, or market conditions) and to earn income and enhance returns.
Risk [Heading]	rr_RiskHeading	PRINCIPAL INVESTMENT RISKS
Risk Narrative [Text Block]	rr_RiskNarrativeTextBlock	The biggest risk is that the Fund's returns will vary, and you could lose money. The Fund is designed for long-term investors seeking an equity portfolio, including common stocks. Common stocks tend to be more volatile than many other investment choices. Value Investing Risk. Because different types of stocks tend to shift in and out of favor depending on market and economic conditions, "value" stocks may perform differently than other types of stocks and from the market as a whole, and can continue to be undervalued by the market for long periods of time. It is also possible that a value stock will never appreciate to the extent expected by the portfolio managers. When the Fund's investments in cash or similar investments increase due to a lack of favorable investment opportunities or other extraordinary factors, the Fund may not participate in market advances or declines to the same extent that it would if the Fund had been fully invested. Market Risk. The value of the Fund's portfolio may decrease if the value of an individual company or security, or multiple companies or securities, in the portfolio decreases or if the portfolio managers' belief about a company's intrinsic worth is incorrect. Further, regardless of how well individual companies or securities perform, the value of the Fund's portfolio could also decrease if there are deteriorating economic or market conditions. It is important to understand that the value of your investment may fall, sometimes sharply, in response to changes in the market, and you could lose money. Foreign Exposure Risk. The Fund may have exposure to foreign markets as a result of its investments in foreign securities, including investments in emerging markets, which can be more volatile than the U.S. markets. As a result, its returns and net asset value may be affected to a large degree by fluctuations in currency exchange rates or political or economic conditions in a particular country. In some foreign markets, there may not be protection against failure by other parties to complete transactions. It may not be possible for the Fund to repatriate capital, dividends, interest, and other income from a particular country or governmental entity. In addition, a market swing in one or more countries or regions where the Fund has invested a significant amount of its assets may have a greater effect on the Fund's performance than it would in a more geographically diversified portfolio. To the extent the Fund invests in foreign debt securities, such investments are sensitive to changes in interest rates. Additionally, investments in securities of foreign governments involve the risk that a foreign government may not be willing or able to pay interest or repay principal when due. Eurozone Risk. A number of countries in the European Union ("EU") have experienced severe economic and financial difficulties. As a result, financial markets in the EU have been subject to extreme volatility and declines in asset values and liquidity. Responses to these financial problems by European governments, central banks, and others, including austerity measures and reforms, may not work, may result in social unrest, and may limit future growth and economic recovery or have other unintended consequences. Further defaults or restructurings by governments and others of their debt could have additional adverse effects on economies, financial markets, and asset valuations around the world. To the extent that the Fund has exposure to European markets or to transactions tied to the value of the euro, these events could negatively affect the value and liquidity of the Fund's investments. Exchange-Traded Funds Risk. The Fund may invest in ETFs, which are typically open-end investment companies that are traded on a national securities exchange. ETFs typically incur fees, such as investment advisory fees and other operating expenses that are separate from those of the Fund, which will be indirectly paid by the Fund. As a result, the cost of investing in the Fund may be higher than the cost of investing directly in ETFs and may be higher than other mutual funds that invest directly in stocks and bonds. Further, the price movement of an ETF may fluctuate against the underlying securities or commodities it tracks and may result in a loss. Because the value of ETF shares depends on the demand in the market, the Fund may not be able to purchase or sell an ETF at the most optimal time, which could adversely affect the Fund's performance. The ETFs in which the Fund invests are subject to specific risks, depending on the investment strategy of the ETF. In turn, the Fund will be subject to substantially the same risks as those associated with direct exposure to the securities or commodities held by the ETF. Because the Fund may invest in a broad range of ETFs, such risks may include, but are not limited to, leverage risk, foreign exposure risk, and commodities risk. Derivatives Risk. Derivatives can be highly volatile and involve risks in addition to the risks of the underlying referenced securities. Gains or losses from a derivative investment can be substantially greater than the derivative's original cost, and can therefore involve leverage. Leverage may cause the Fund to be more volatile than if it had not used leverage. Derivatives can be less liquid than other types of investments and entail the risk that the counterparty will default on its payment obligations. An investment in the Fund is not a bank deposit and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency.
Risk Lose Money [Text]	rr_RiskLoseMoney	The biggest risk is that the Fund’s returns will vary, and you could lose money.
Risk Not Insured Depository Institution [Text]	rr_RiskNotInsuredDepositoryInstitution	An investment in the Fund is not a bank deposit and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency.
Bar Chart and Performance Table [Heading]	rr_BarChartAndPerformanceTableHeading	PERFORMANCE INFORMATION
Performance Narrative [Text Block]	rr_PerformanceNarrativeTextBlock	The following information provides some indication of the risks of investing in the Fund by showing how the Fund’s performance has varied over time. Class I Shares, Class A Shares, Class C Shares, and Class S Shares of the Fund commenced operations on July 6, 2009, after the reorganization of each corresponding class of shares of Janus Adviser Perkins Large Cap Value Fund (“JAD predecessor fund”) into each respective share class of the Fund. Class T Shares of the Fund commenced operations on July 6, 2009. Class N Shares of the Fund commenced operations on May 31, 2012. The performance shown for Class I Shares, Class A Shares, Class C Shares, and Class S Shares for periods prior to July 6, 2009, reflects the historical performance of the JAD predecessor fund’s Class I Shares, Class A Shares, Class C Shares, and Class S Shares prior to the reorganization, calculated using the fees and expenses of each respective share class of the JAD predecessor fund, net of any applicable fee and expense limitations or waivers. The performance shown for Class N Shares reflects the performance of the Fund’s Class I Shares from July 6, 2009 to May 31, 2012, calculated using the fees and expenses of Class I Shares, net of any applicable fee and expense limitations or waivers. The performance shown for Class N Shares for periods prior to July 6, 2009, reflects the historical performance of the JAD predecessor fund’s Class I Shares prior to the reorganization, calculated using the fees and expenses of Class I Shares of the JAD predecessor fund, net of any applicable fee and expense limitations or waivers. The performance shown for Class T Shares for periods prior to July 6, 2009, reflects the historical performance of the JAD predecessor fund’s Class I Shares prior to the reorganization, calculated using the fees and expenses of Class T Shares, without the effect of any fee and expense limitations or waivers. If Class T Shares of the Fund had been available during periods prior to July 6, 2009, or Class N Shares of the Fund had been available during periods prior to May 31, 2012, the performance shown for each respective share class may have been different. The performance shown for periods following the Fund’s commencement of Class I Shares, Class A Shares, Class C Shares, Class S Shares, Class N Shares, and Class T Shares reflects the fees and expenses of each respective share class, net of any applicable fee and expense limitations or waivers. The bar chart depicts the change in performance from year to year during the periods indicated. The bar chart figures do not include any applicable sales charges that an investor may pay when they buy or sell Class A Shares or Class C Shares of the Fund. If sales charges were included, the returns would be lower. The table compares the Fund’s average annual returns for the periods indicated to a broad-based securities market index. The index is not actively managed and is not available for direct investment. All figures assume reinvestment of dividends and distributions. For certain periods, the Fund’s performance reflects the effect of expense waivers. Without the effect of these expense waivers, the performance shown would have been lower. The Fund’s past performance (before and after taxes) does not necessarily indicate how it will perform in the future. Updated performance information is available at janus.com/advisor/mutual-funds or by calling 1-877-335-2687.
Performance Information Illustrates Variability of Returns [Text]	rr_PerformanceInformationIllustratesVariabilityOfReturns	The following information provides some indication of the risks of investing in the Fund by showing how the Fund’s performance has varied over time. The bar chart depicts the change in performance from year to year during the periods indicated.
Performance Additional Market Index [Text]	rr_PerformanceAdditionalMarketIndex	The table compares the Fund’s average annual returns for the periods indicated to a broad-based securities market index. The index is not actively managed and is not available for direct investment. All figures assume reinvestment of dividends and distributions.
Performance Availability Phone [Text]	rr_PerformanceAvailabilityPhone	1-877-335-2687
Performance Availability Website Address [Text]	rr_PerformanceAvailabilityWebSiteAddress	janus.com/advisor/mutual-funds
Performance Past Does Not Indicate Future [Text]	rr_PerformancePastDoesNotIndicateFuture	The Fund’s past performance (before and after taxes) does not necessarily indicate how it will perform in the future.
Bar Chart [Heading]	rr_BarChartHeading	Annual Total Returns for Class I Shares (calendar year-end)
Bar Chart Does Not Reflect Sales Loads [Text]	rr_BarChartDoesNotReflectSalesLoads	The bar chart figures do not include any applicable sales charges that an investor may pay when they buy or sell Class A Shares or Class C Shares of the Fund. If sales charges were included, the returns would be lower.
Bar Chart Closing [Text Block]	rr_BarChartClosingTextBlock	Best Quarter:  Second Quarter 2009  15.40%          Worst Quarter:  Third Quarter 2011  −14.75%
Year to Date Return, Label	rr_YearToDateReturnLabel	The Fund’s year-to-date return as of the calendar quarter ended September 30, 2013 was 18.00%.
Performance Table Heading	rr_PerformanceTableHeading	Average Annual Total Returns (periods ended 12/31/12)
Performance Table Uses Highest Federal Rate	rr_PerformanceTableUsesHighestFederalRate	After-tax returns are calculated using the historically highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes.
Performance Table Not Relevant to Tax Deferred	rr_PerformanceTableNotRelevantToTaxDeferred	Actual after-tax returns depend on your individual tax situation and may differ from those shown in the preceding table. The after-tax return information shown above does not apply to Fund shares held through a tax-deferred account, such as a 401(k) plan or an IRA.
Performance Table One Class of after Tax Shown [Text]	rr_PerformanceTableOneClassOfAfterTaxShown	After-tax returns are only shown for Class I Shares of the Fund. After-tax returns for the other classes of Shares will vary from those shown for Class I Shares due to varying sales charges (as applicable), fees, and expenses among the classes.
Performance Table Narrative	rr_PerformanceTableNarrativeTextBlock	The Russell 1000® Value Index measures the performance of those Russell 1000® companies with lower price-to-book ratios and lower forecasted growth values. This index is used to calculate the performance fee adjustment. After-tax returns are calculated using distributions for the Fund’s Class I Shares for periods following July 6, 2009; and for the JAD predecessor fund’s Class I Shares for periods prior to July 6, 2009. After-tax returns are calculated using the historically highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes. Actual after-tax returns depend on your individual tax situation and may differ from those shown in the preceding table. The after-tax return information shown above does not apply to Fund shares held through a tax-deferred account, such as a 401(k) plan or an IRA. After-tax returns are only shown for Class I Shares of the Fund. After-tax returns for the other classes of Shares will vary from those shown for Class I Shares due to varying sales charges (as applicable), fees, and expenses among the classes.
Performance Table Closing [Text Block]	rr_PerformanceTableClosingTextBlock	Updated performance information is available at janus.com/advisor/mutual-funds or by calling 1-877-335-2687.
Perkins Large Cap Value Fund | Class A, C, S, I, N, T Shares | Class A
Risk/Return:	rr_RiskReturnAbstract
Shareholder Fees Column [Text]	rr_ShareholderFeesColumnName	Class A
Maximum Sales Charge (load) Imposed on Purchases (as a percentage of offering price)	rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice	5.75%
Maximum Deferred Sales Charge (load) (as a percentage of the lower of original purchase price or redemption proceeds)	rr_MaximumDeferredSalesChargeOverOther	none
Operating Expenses Column [Text]	rr_OperatingExpensesColumnName	Class A
Management Fees (may adjust up or down)	rr_ManagementFeesOverAssets	0.52%
Distribution/Service (12b-1) Fees	rr_DistributionAndService12b1FeesOverAssets	0.25%
Other Expenses	rr_OtherExpensesOverAssets	0.38%
Total Annual Fund Operating Expenses	rr_ExpensesOverAssets	1.15%	[1]
Fee Waiver	rr_FeeWaiverOrReimbursementOverAssets	0.07%	[1]
Total Annual Fund Operating Expenses After Fee Waiver	rr_NetExpensesOverAssets	1.08%	[1]
Expense Example, By Year, Column [Text]	rr_ExpenseExampleByYearColumnName	Class A Shares
1 Year	rr_ExpenseExampleYear01	685
3 Years	rr_ExpenseExampleYear03	919
5 Years	rr_ExpenseExampleYear05	1,172
10 Years	rr_ExpenseExampleYear10	1,892
Expense Example, No Redemption, By Year, Column [Text]	rr_ExpenseExampleNoRedemptionByYearColumnName	Class A Shares
1 Year	rr_ExpenseExampleNoRedemptionYear01	685
3 Years	rr_ExpenseExampleNoRedemptionYear03	919
5 Years	rr_ExpenseExampleNoRedemptionYear05	1,172
10 Years	rr_ExpenseExampleNoRedemptionYear10	1,892
Perkins Large Cap Value Fund | Class A, C, S, I, N, T Shares | Class C
Risk/Return:	rr_RiskReturnAbstract
Shareholder Fees Column [Text]	rr_ShareholderFeesColumnName	Class C
Maximum Sales Charge (load) Imposed on Purchases (as a percentage of offering price)	rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice	none
Maximum Deferred Sales Charge (load) (as a percentage of the lower of original purchase price or redemption proceeds)	rr_MaximumDeferredSalesChargeOverOther	1.00%
Operating Expenses Column [Text]	rr_OperatingExpensesColumnName	Class C
Management Fees (may adjust up or down)	rr_ManagementFeesOverAssets	0.52%
Distribution/Service (12b-1) Fees	rr_DistributionAndService12b1FeesOverAssets	1.00%
Other Expenses	rr_OtherExpensesOverAssets	0.29%
Total Annual Fund Operating Expenses	rr_ExpensesOverAssets	1.81%	[1]
Fee Waiver	rr_FeeWaiverOrReimbursementOverAssets	0.08%	[1]
Total Annual Fund Operating Expenses After Fee Waiver	rr_NetExpensesOverAssets	1.73%	[1]
Expense Example, By Year, Column [Text]	rr_ExpenseExampleByYearColumnName	Class C Shares
1 Year	rr_ExpenseExampleYear01	284
3 Years	rr_ExpenseExampleYear03	569
5 Years	rr_ExpenseExampleYear05	980
10 Years	rr_ExpenseExampleYear10	2,127
Expense Example, No Redemption, By Year, Column [Text]	rr_ExpenseExampleNoRedemptionByYearColumnName	Class C Shares
1 Year	rr_ExpenseExampleNoRedemptionYear01	184
3 Years	rr_ExpenseExampleNoRedemptionYear03	569
5 Years	rr_ExpenseExampleNoRedemptionYear05	980
10 Years	rr_ExpenseExampleNoRedemptionYear10	2,127
Perkins Large Cap Value Fund | Class A, C, S, I, N, T Shares | Class S
Risk/Return:	rr_RiskReturnAbstract
Shareholder Fees Column [Text]	rr_ShareholderFeesColumnName	Class S
Maximum Sales Charge (load) Imposed on Purchases (as a percentage of offering price)	rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice	none
Maximum Deferred Sales Charge (load) (as a percentage of the lower of original purchase price or redemption proceeds)	rr_MaximumDeferredSalesChargeOverOther	none
Operating Expenses Column [Text]	rr_OperatingExpensesColumnName	Class S
Management Fees (may adjust up or down)	rr_ManagementFeesOverAssets	0.52%
Distribution/Service (12b-1) Fees	rr_DistributionAndService12b1FeesOverAssets	0.25%
Other Expenses	rr_OtherExpensesOverAssets	0.42%
Total Annual Fund Operating Expenses	rr_ExpensesOverAssets	1.19%	[1]
Fee Waiver	rr_FeeWaiverOrReimbursementOverAssets	0.06%	[1]
Total Annual Fund Operating Expenses After Fee Waiver	rr_NetExpensesOverAssets	1.13%	[1]
Expense Example, By Year, Column [Text]	rr_ExpenseExampleByYearColumnName	Class S Shares
1 Year	rr_ExpenseExampleYear01	121
3 Years	rr_ExpenseExampleYear03	378
5 Years	rr_ExpenseExampleYear05	654
10 Years	rr_ExpenseExampleYear10	1,443
Expense Example, No Redemption, By Year, Column [Text]	rr_ExpenseExampleNoRedemptionByYearColumnName	Class S Shares
1 Year	rr_ExpenseExampleNoRedemptionYear01	121
3 Years	rr_ExpenseExampleNoRedemptionYear03	378
5 Years	rr_ExpenseExampleNoRedemptionYear05	654
10 Years	rr_ExpenseExampleNoRedemptionYear10	1,433
Perkins Large Cap Value Fund | Class A, C, S, I, N, T Shares | Class I
Risk/Return:	rr_RiskReturnAbstract
Shareholder Fees Column [Text]	rr_ShareholderFeesColumnName	Class I
Maximum Sales Charge (load) Imposed on Purchases (as a percentage of offering price)	rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice	none
Maximum Deferred Sales Charge (load) (as a percentage of the lower of original purchase price or redemption proceeds)	rr_MaximumDeferredSalesChargeOverOther	none
Operating Expenses Column [Text]	rr_OperatingExpensesColumnName	Class I
Management Fees (may adjust up or down)	rr_ManagementFeesOverAssets	0.52%
Distribution/Service (12b-1) Fees	rr_DistributionAndService12b1FeesOverAssets	none
Other Expenses	rr_OtherExpensesOverAssets	0.19%
Total Annual Fund Operating Expenses	rr_ExpensesOverAssets	0.71%	[1]
Fee Waiver	rr_FeeWaiverOrReimbursementOverAssets	0.07%	[1]
Total Annual Fund Operating Expenses After Fee Waiver	rr_NetExpensesOverAssets	0.64%	[1]
Expense Example, By Year, Column [Text]	rr_ExpenseExampleByYearColumnName	Class I Shares
1 Year	rr_ExpenseExampleYear01	73
3 Years	rr_ExpenseExampleYear03	227
5 Years	rr_ExpenseExampleYear05	395
10 Years	rr_ExpenseExampleYear10	883
Expense Example, No Redemption, By Year, Column [Text]	rr_ExpenseExampleNoRedemptionByYearColumnName	Class I Shares
1 Year	rr_ExpenseExampleNoRedemptionYear01	73
3 Years	rr_ExpenseExampleNoRedemptionYear03	227
5 Years	rr_ExpenseExampleNoRedemptionYear05	395
10 Years	rr_ExpenseExampleNoRedemptionYear10	883
2009	rr_AnnualReturn2009	25.15%
2010	rr_AnnualReturn2010	12.19%
2011	rr_AnnualReturn2011	(0.20%)
2012	rr_AnnualReturn2012	13.33%
Bar Chart, Year to Date Return, Date	rr_BarChartYearToDateReturnDate	Sep. 30, 2013
Bar Chart, Year to Date Return	rr_BarChartYearToDateReturn	18.00%
Highest Quarterly Return, Label	rr_HighestQuarterlyReturnLabel	Best Quarter:
Highest Quarterly Return, Date	rr_BarChartHighestQuarterlyReturnDate	Jun. 30, 2009
Highest Quarterly Return	rr_BarChartHighestQuarterlyReturn	15.40%
Lowest Quarterly Return, Label	rr_LowestQuarterlyReturnLabel	Worst Quarter:
Lowest Quarterly Return, Date	rr_BarChartLowestQuarterlyReturnDate	Sep. 30, 2011
Lowest Quarterly Return	rr_BarChartLowestQuarterlyReturn	(14.75%)
Perkins Large Cap Value Fund | Class A, C, S, I, N, T Shares | Class N
Risk/Return:	rr_RiskReturnAbstract
Shareholder Fees Column [Text]	rr_ShareholderFeesColumnName	Class N
Maximum Sales Charge (load) Imposed on Purchases (as a percentage of offering price)	rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice	none
Maximum Deferred Sales Charge (load) (as a percentage of the lower of original purchase price or redemption proceeds)	rr_MaximumDeferredSalesChargeOverOther	none
Operating Expenses Column [Text]	rr_OperatingExpensesColumnName	Class N
Management Fees (may adjust up or down)	rr_ManagementFeesOverAssets	0.52%
Distribution/Service (12b-1) Fees	rr_DistributionAndService12b1FeesOverAssets	none
Other Expenses	rr_OtherExpensesOverAssets	0.16%
Total Annual Fund Operating Expenses	rr_ExpensesOverAssets	0.68%	[1]
Fee Waiver	rr_FeeWaiverOrReimbursementOverAssets	0.05%	[1]
Total Annual Fund Operating Expenses After Fee Waiver	rr_NetExpensesOverAssets	0.63%	[1]
Expense Example, By Year, Column [Text]	rr_ExpenseExampleByYearColumnName	Class N Shares
1 Year	rr_ExpenseExampleYear01	69
3 Years	rr_ExpenseExampleYear03	218
5 Years	rr_ExpenseExampleYear05	379
10 Years	rr_ExpenseExampleYear10	847
Expense Example, No Redemption, By Year, Column [Text]	rr_ExpenseExampleNoRedemptionByYearColumnName	Class N Shares
1 Year	rr_ExpenseExampleNoRedemptionYear01	69
3 Years	rr_ExpenseExampleNoRedemptionYear03	218
5 Years	rr_ExpenseExampleNoRedemptionYear05	379
10 Years	rr_ExpenseExampleNoRedemptionYear10	847
Perkins Large Cap Value Fund | Class A, C, S, I, N, T Shares | Class T
Risk/Return:	rr_RiskReturnAbstract
Shareholder Fees Column [Text]	rr_ShareholderFeesColumnName	Class T
Maximum Sales Charge (load) Imposed on Purchases (as a percentage of offering price)	rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice	none
Maximum Deferred Sales Charge (load) (as a percentage of the lower of original purchase price or redemption proceeds)	rr_MaximumDeferredSalesChargeOverOther	none
Operating Expenses Column [Text]	rr_OperatingExpensesColumnName	Class T
Management Fees (may adjust up or down)	rr_ManagementFeesOverAssets	0.52%
Distribution/Service (12b-1) Fees	rr_DistributionAndService12b1FeesOverAssets	none
Other Expenses	rr_OtherExpensesOverAssets	0.42%
Total Annual Fund Operating Expenses	rr_ExpensesOverAssets	0.94%	[1]
Fee Waiver	rr_FeeWaiverOrReimbursementOverAssets	0.06%	[1]
Total Annual Fund Operating Expenses After Fee Waiver	rr_NetExpensesOverAssets	0.88%	[1]
Expense Example, By Year, Column [Text]	rr_ExpenseExampleByYearColumnName	Class T Shares
1 Year	rr_ExpenseExampleYear01	96
3 Years	rr_ExpenseExampleYear03	300
5 Years	rr_ExpenseExampleYear05	520
10 Years	rr_ExpenseExampleYear10	1,155
Expense Example, No Redemption, By Year, Column [Text]	rr_ExpenseExampleNoRedemptionByYearColumnName	Class T Shares
1 Year	rr_ExpenseExampleNoRedemptionYear01	96
3 Years	rr_ExpenseExampleNoRedemptionYear03	300
5 Years	rr_ExpenseExampleNoRedemptionYear05	520
10 Years	rr_ExpenseExampleNoRedemptionYear10	$ 1,155
Perkins Large Cap Value Fund | Class A, C, S, I, N, T Shares | Return Before Taxes | Class A
Risk/Return:	rr_RiskReturnAbstract
Column	rr_AverageAnnualReturnColumnName	Class A Shares
Label	rr_AverageAnnualReturnLabel	Return Before Taxes	[2]
1 Year	rr_AverageAnnualReturnYear01	6.45%
Since Inception of Predecessor Fund	rr_AverageAnnualReturnSinceInception	10.27%
Inception Date	rr_AverageAnnualReturnInceptionDate	Dec. 31, 2008
Perkins Large Cap Value Fund | Class A, C, S, I, N, T Shares | Return Before Taxes | Class C
Risk/Return:	rr_RiskReturnAbstract
Column	rr_AverageAnnualReturnColumnName	Class C Shares
Label	rr_AverageAnnualReturnLabel	Return Before Taxes	[3]
1 Year	rr_AverageAnnualReturnYear01	10.90%
Since Inception of Predecessor Fund	rr_AverageAnnualReturnSinceInception	11.05%
Inception Date	rr_AverageAnnualReturnInceptionDate	Dec. 31, 2008
Perkins Large Cap Value Fund | Class A, C, S, I, N, T Shares | Return Before Taxes | Class S
Risk/Return:	rr_RiskReturnAbstract
Column	rr_AverageAnnualReturnColumnName	Class S Shares
Label	rr_AverageAnnualReturnLabel	Return Before Taxes
1 Year	rr_AverageAnnualReturnYear01	12.93%
Since Inception of Predecessor Fund	rr_AverageAnnualReturnSinceInception	11.75%
Inception Date	rr_AverageAnnualReturnInceptionDate	Dec. 31, 2008
Perkins Large Cap Value Fund | Class A, C, S, I, N, T Shares | Return Before Taxes | Class I
Risk/Return:	rr_RiskReturnAbstract
Column	rr_AverageAnnualReturnColumnName	Class I Shares
Label	rr_AverageAnnualReturnLabel	Return Before Taxes
1 Year	rr_AverageAnnualReturnYear01	13.33%
Since Inception of Predecessor Fund	rr_AverageAnnualReturnSinceInception	12.26%
Inception Date	rr_AverageAnnualReturnInceptionDate	Dec. 31, 2008
Perkins Large Cap Value Fund | Class A, C, S, I, N, T Shares | Return Before Taxes | Class N
Risk/Return:	rr_RiskReturnAbstract
Column	rr_AverageAnnualReturnColumnName	Class N Shares
Label	rr_AverageAnnualReturnLabel	Return Before Taxes
1 Year	rr_AverageAnnualReturnYear01	13.33%
Since Inception of Predecessor Fund	rr_AverageAnnualReturnSinceInception	12.26%
Inception Date	rr_AverageAnnualReturnInceptionDate	Dec. 31, 2008
Perkins Large Cap Value Fund | Class A, C, S, I, N, T Shares | Return Before Taxes | Class T
Risk/Return:	rr_RiskReturnAbstract
Column	rr_AverageAnnualReturnColumnName	Class T Shares
Label	rr_AverageAnnualReturnLabel	Return Before Taxes
1 Year	rr_AverageAnnualReturnYear01	13.08%
Since Inception of Predecessor Fund	rr_AverageAnnualReturnSinceInception	11.88%
Inception Date	rr_AverageAnnualReturnInceptionDate	Dec. 31, 2008
Perkins Large Cap Value Fund | Class A, C, S, I, N, T Shares | Return After Taxes on Distributions | Class I
Risk/Return:	rr_RiskReturnAbstract
Column	rr_AverageAnnualReturnColumnName	Class I Shares
Label	rr_AverageAnnualReturnLabel	Return After Taxes on Distributions
1 Year	rr_AverageAnnualReturnYear01	12.76%
Since Inception of Predecessor Fund	rr_AverageAnnualReturnSinceInception	11.51%
Inception Date	rr_AverageAnnualReturnInceptionDate	Dec. 31, 2008
Perkins Large Cap Value Fund | Class A, C, S, I, N, T Shares | Return After Taxes on Distributions and Sale of Fund Shares | Class I
Risk/Return:	rr_RiskReturnAbstract
Column	rr_AverageAnnualReturnColumnName	Class I Shares
Label	rr_AverageAnnualReturnLabel	Return After Taxes on Distributions and Sale of Fund Shares
1 Year	rr_AverageAnnualReturnYear01	9.44%
Since Inception of Predecessor Fund	rr_AverageAnnualReturnSinceInception	10.45%
Inception Date	rr_AverageAnnualReturnInceptionDate	Dec. 31, 2008
Perkins Large Cap Value Fund | Class A, C, S, I, N, T Shares | Russell 1000® Value Index (reflects no deduction for expenses, fees, or taxes)
Risk/Return:	rr_RiskReturnAbstract
Label	rr_AverageAnnualReturnLabel	Russell 1000® Value Index
1 Year	rr_AverageAnnualReturnYear01	17.51%
Since Inception of Predecessor Fund	rr_AverageAnnualReturnSinceInception	13.01%
Inception Date	rr_AverageAnnualReturnInceptionDate	Dec. 31, 2008

[1] Janus Capital has contractually agreed to waive its investment advisory fee and/or reimburse Fund expenses to the extent that the Fund's total annual fund operating expenses (excluding any performance adjustments to management fees, the distribution and shareholder servicing fees– applicable to Class A Shares, Class C Shares, and Class S Shares; administrative services fees payable pursuant to the Transfer Agency Agreement; brokerage commissions; interest; dividends; taxes; acquired fund fees and expenses; and extraordinary expenses) exceed 0.75% until at least November 1, 2014. The contractual waiver may be terminated or modified prior to this date only at the discretion of the Board of Trustees.

[2] Calculated assuming maximum permitted sales loads.

[3] The one year return is calculated to include the contingent deferred sales charge.

XML

Label	Element	Value
Risk/Return:	rr_RiskReturnAbstract
Registrant Name	dei_EntityRegistrantName	JANUS INVESTMENT FUND
Prospectus Date	rr_ProspectusDate	Oct. 28, 2013
Janus Global Allocation Fund - Conservative | Class A, C, S, I, T Shares
Risk/Return:	rr_RiskReturnAbstract
Risk/Return [Heading]	rr_RiskReturnHeading	FUND SUMMARY Janus Global Allocation Fund – Conservative (formerly named Janus Conservative Allocation Fund)
Objective [Heading]	rr_ObjectiveHeading	INVESTMENT OBJECTIVE
Objective, Primary [Text Block]	rr_ObjectivePrimaryTextBlock	Janus Global Allocation Fund – Conservative seeks total return through a primary emphasis on income with a secondary emphasis on growth of capital.
Expense [Heading]	rr_ExpenseHeading	FEES AND EXPENSES OF THE FUND
Expense Narrative [Text Block]	rr_ExpenseNarrativeTextBlock	This table describes the fees and expenses that you may pay if you buy and hold Shares of the Fund. Each share class has different expenses, but represents an investment in the same Fund.
Shareholder Fees Caption [Text]	rr_ShareholderFeesCaption	SHAREHOLDER FEES (fees paid directly from your investment)
Operating Expenses Caption [Text]	rr_OperatingExpensesCaption	ANNUAL FUND OPERATING EXPENSES (expenses that you pay each year as a percentage of the value of your investment)
Portfolio Turnover [Heading]	rr_PortfolioTurnoverHeading	Portfolio Turnover:
Portfolio Turnover [Text Block]	rr_PortfolioTurnoverTextBlock	The Fund pays transaction costs, such as commissions, when it buys and sells securities (or “turns over” its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when Fund shares are held in a taxable account. These costs, which are not reflected in annual fund operating expenses or in the Example, affect the Fund’s performance. During the most recent fiscal year, the Fund’s portfolio turnover rate was 69% of the average value of its portfolio.
Portfolio Turnover, Rate	rr_PortfolioTurnoverRate	69.00%
Expense Breakpoint Discounts [Text]	rr_ExpenseBreakpointDiscounts	For Class A Shares, you may qualify for sales charge discounts if you and your family invest, or agree to invest in the future, at least $50,000 in the Fund or in other Janus mutual funds. More information about these and other discounts, as well as eligibility requirements for each share class, is available from your financial professional and in the “Purchases” section on page 52 of the Fund’s Prospectus and in the “Purchases” section on page 57 of the Fund’s Statement of Additional Information.
Expense Breakpoint, Minimum Investment Required [Amount]	rr_ExpenseBreakpointMinimumInvestmentRequiredAmount	$ 50,000
Expense Example [Heading]	rr_ExpenseExampleHeading	EXAMPLE:
Expense Example by Year [Heading]	rr_ExpenseExampleByYearHeading	The Example assumes that you invest $10,000 in the Fund for the time periods indicated and reinvest all dividends and distributions. The Example also assumes that your investment has a 5% return each year and that the Fund’s operating expenses (including the operating expenses of the underlying funds) remain the same. Although your actual costs may be higher or lower, based on these assumptions your costs would be:
Expense Example Narrative [Text Block]	rr_ExpenseExampleNarrativeTextBlock	The Example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds.
Expense Example by, Year, Caption [Text]	rr_ExpenseExampleByYearCaption	If Shares are redeemed:
Expense Example, No Redemption, By Year, Caption [Text]	rr_ExpenseExampleNoRedemptionByYearCaption	If Shares are not redeemed:
Strategy [Heading]	rr_StrategyHeading	PRINCIPAL INVESTMENT STRATEGIES
Strategy Narrative [Text Block]	rr_StrategyNarrativeTextBlock	The Fund seeks to achieve its investment objective by investing in other Janus mutual funds (“underlying funds”) that represent a variety of asset classes and investment styles and provide exposure to issuers that are economically tied to countries throughout the world. Through its investments in underlying funds, the Fund invests in issuers from several different countries and may, under unusual circumstances, be invested in a single country. As a result, the Fund normally will have approximately 40% of its net assets allocated to non-U.S. investments. The Fund may also have significant exposure to emerging markets. The Fund pursues this objective by investing in a diversified portfolio of underlying funds, resulting in an allocation of the Fund’s investments that normally provides exposure of approximately 55% to fixed-income securities and money market instruments, 40% to equity investments, and 5% to alternative investments. The target allocation and the allocation of the Fund’s assets among underlying funds are based on quantitative and qualitative analysis. Because it invests in other funds, the Fund is considered a “fund of funds.” The Fund’s asset allocation is intended to diversify investments throughout the world among equity investments, fixed-income securities, cash equivalents, and alternative investments. The portfolio manager determines the overall composition of the Fund, oversees the investment process, and is responsible for the day-to-day management of the Fund. The portfolio manager continually monitors asset class allocations and periodically rebalances the Fund’s investments in the underlying funds. The portfolio manager also regularly reviews the allocation of Fund assets in the underlying funds and may modify the underlying funds’ weightings or substitute other underlying funds to emphasize and mitigate risk exposures that may arise as a result of the implementation of the allocations. An independent asset allocation service provides evaluations of asset allocations that the portfolio manager may use in implementing the allocations among the underlying funds. Additionally, the portfolio manager consults with a committee (the “Janus Global Allocation Committee”) to regularly review the broad market, macroeconomic conditions and other global financial factors that may impact the Fund’s allocation of assets among the underlying funds and asset classes. The Janus Global Allocation Committee is comprised of investment professionals of Janus Capital and may also include investment professionals of Janus Capital’s affiliated investment advisers. The portfolio manager and Janus Global Allocation Committee normally meet on a quarterly basis. The portfolio manager may change the Fund’s asset class allocations, the underlying funds, an underlying fund’s asset category, or weightings among asset classes or underlying funds without prior shareholder notice. The Fund will normally allocate approximately 55% of its investments to underlying bond funds and money market instruments, approximately 40% of its investments to underlying funds that provide varying exposure to common stocks of large U.S.-based companies, small- to mid-capitalization companies, and international companies (including those with exposure to emerging markets), and approximately 5% of its investments to underlying funds that seek returns uncorrelated with the returns of stocks and bonds by providing exposure to alternative investments and alternative investment strategies. Refer to Appendix A in this Prospectus for a brief description of the investment strategies of each of the currently available underlying funds. When market conditions dictate a more defensive strategy, the Fund or an underlying fund may temporarily hold cash or invest its assets in temporary investments. In that case, the Fund may take positions that are inconsistent with its investment objective. As a result, the Fund may not achieve its investment objective.
Risk [Heading]	rr_RiskHeading	PRINCIPAL INVESTMENT RISKS
Risk Narrative [Text Block]	rr_RiskNarrativeTextBlock	The biggest risk is that the Fund’s returns will vary, and you could lose money. The Fund is designed for long-term investors seeking income and, to a lesser extent, growth of capital. Investments in a portfolio with common stock and alternative investment exposure tend to be more volatile than many other investment choices. Main Risks Associated with the Fund Allocation Risk. The Fund’s ability to achieve its investment objective depends largely upon the portfolio manager’s allocation of assets among the underlying funds and other securities, using the optimization process (a process that utilizes quantitative analysis of a number of factors, such as historical risk, performance, fund classifications, and the relationship among underlying funds) and the judgment of the portfolio manager. You could lose money on your investment in the Fund as a result of these allocations. The Fund will typically invest in a number of different underlying funds; however, to the extent that the Fund invests a significant portion of its assets in a single underlying fund, it will be more sensitive to the risks associated with that fund and any investments in which that fund focuses. Affiliated Fund Risk. Janus Capital has the authority to select and substitute underlying affiliated mutual funds. The fees paid to Janus Capital by some Janus mutual funds are generally higher than the fees paid to Janus Capital by the Fund or by other funds and share classes available for investment by the Fund. These conditions may create a conflict of interest when selecting underlying affiliated mutual funds and share classes for investment. Janus Capital, however, is a fiduciary to the Fund and its shareholders and is legally obligated to act in their best interest when selecting underlying affiliated mutual funds. Main Risks Associated with the Underlying Funds and Securities The biggest risk is that the underlying funds’ returns will vary, and you could lose money. Fixed-Income Securities Risk. Approximately 55% of the Fund’s assets are allocated to fixed-income securities through investments in underlying funds. Typically, the values of fixed-income securities change inversely with prevailing interest rates. Therefore, a fundamental risk of fixed-income securities is interest rate risk, which is the risk that the value of such securities will generally decline as prevailing interest rates rise, which may cause an underlying fund’s net asset value to likewise decrease. How specific fixed-income securities may react to changes in interest rates will depend on the specific characteristics of each security. Fixed-income securities are also subject to credit risk, prepayment risk, valuation risk, and liquidity risk. Credit risk is the risk that the credit strength of an issuer of a fixed-income security will weaken and/or that the issuer will be unable to make timely principal and interest payments and that the security may go into default. Prepayment risk is the risk that during periods of falling interest rates, certain fixed-income securities with higher interest rates, such as mortgage- and asset-backed securities, may be prepaid by their issuers thereby reducing the amount of interest payments. Valuation risk is the risk that one or more of the fixed-income securities in which an underlying fund invests are priced differently than the value realized upon such security’s sale. In times of market instability, valuation may be more difficult. Liquidity risk is the risk that fixed-income securities may be difficult or impossible to sell at the time that an underlying fund’s portfolio manager would like or at the price the portfolio manager believes the security is currently worth. Mortgage-Backed Securities Risk. Mortgage-backed securities are classified generally as either commercial mortgage-backed securities or residential mortgage-backed securities, each of which is subject to certain specific risks. Mortgage-backed securities tend to be more sensitive to changes in interest rates than other types of debt securities. Investments in mortgage-backed securities are subject to both extension risk, where borrowers extend the duration of their mortgages in times of rising interest rates, and prepayment risk, where borrowers pay off their mortgages sooner than expected in times of declining interest rates. These risks may reduce the Fund’s returns. In addition, investments in mortgage-backed securities, including those comprised of subprime mortgages, may be subject to a higher degree of credit risk, valuation risk, and liquidity risk than various other types of fixed-income securities. Market Risk. Approximately 40% of the Fund’s assets are allocated to equity investments through investments in underlying funds. The value of an underlying fund’s portfolio may decrease if the value of an individual company or security, or multiple companies or securities, in the portfolio decreases or if a portfolio manager’s belief about a company’s intrinsic worth is incorrect. Further, regardless of how well individual companies or securities perform, the value of an underlying fund’s portfolio could also decrease if there are deteriorating economic or market conditions. It is important to understand that the value of your investment may fall, sometimes sharply, in response to changes in the market, and you could lose money. Foreign Exposure Risk. Certain underlying funds may have significant exposure to foreign markets as a result of their investments in foreign securities, including investments in emerging markets, which can be more volatile than the U.S. markets. As a result, an underlying fund’s returns and net asset value may be affected to a large degree by fluctuations in currency exchange rates or political or economic conditions in a particular country. A market swing in one or more countries or regions where an underlying fund has invested a significant amount of its assets may have a greater effect on an underlying fund’s performance than it would in a more geographically diversified portfolio. An underlying fund’s investments in emerging market countries may involve risks greater than, or in addition to, the risks of investing in more developed countries. Emerging Markets Risk. The risks of foreign investing mentioned above are heightened when investing in emerging markets. Emerging markets securities involve a number of additional risks, which may result from less government supervision and regulation of business and industry practices (including the potential lack of strict finance and accounting controls and standards), stock exchanges, brokers, and listed companies, making these investments potentially more volatile in price and less liquid than investments in developed securities markets, resulting in greater risk to investors. In addition, an underlying fund’s investments may be denominated in foreign currencies and therefore, changes in the value of a country’s currency compared to the U.S. dollar may affect the value of an underlying fund’s investments. To the extent that an underlying fund invests a significant portion of its assets in the securities of issuers in or companies of a single country or region, it is more likely to be impacted by events or conditions affecting that country or region, which could have a negative impact on the Fund’s performance. Some of the risks of investing directly in foreign and emerging market securities may be reduced when an underlying fund invests indirectly in foreign securities through various other investment vehicles including derivatives, which also involve other risks. Sovereign Debt Risk. An underlying fund may invest in U.S. and foreign government debt securities (“sovereign debt”). Investments in U.S. sovereign debt are considered low risk. However, investments in non-U.S. sovereign debt can involve a high degree of risk, including the risk that the governmental entity that controls the repayment of sovereign debt may not be willing or able to repay the principal and/or to pay the interest on its sovereign debt in a timely manner. A sovereign debtor’s willingness or ability to satisfy its debt obligation may be affected by various factors including, but not limited to, its cash flow situation, the extent of its foreign currency reserves, the availability of foreign exchange when a payment is due, and the relative size of its debt position in relation to its economy as a whole. In the event of default, there may be limited or no legal remedies for collecting sovereign debt and there may be no bankruptcy proceedings through which the underlying fund may collect all or part of the sovereign debt that a governmental entity has not repaid. Alternative Investments Allocation Risk. Approximately 5% of the Fund’s assets are allocated to alternative investments through investments in underlying funds that invest in alternative investment strategies. In connection with the Fund’s allocation to alternative investments, the Fund may invest in a Janus underlying fund, Janus Diversified Alternatives Fund, which seeks returns uncorrelated with the returns generated by investments in stocks and bonds. In addition, as part of its alternative investments allocation, the Fund may invest in Janus Global Real Estate Fund. Janus Diversified Alternatives Fund’s ability to achieve its investment objective depends largely upon the successful evaluation of the risk, potential returns, and correlation properties with respect to its investments. There is a risk that the returns provided by alternative investments may be subject to high volatility and that an underlying fund’s portfolio manager’s beliefs about the expected returns, risk and correlation properties of one or more of an underlying fund’s investments may be incorrect. There is also a risk that an underlying fund’s investments will correlate with the performance of stocks and bonds to a greater degree than anticipated. Janus Capital does not have prior experience managing the investment strategy of Janus Diversified Alternatives Fund, and there is no guarantee that the investment techniques and analysis used by the underlying fund’s portfolio managers will produce the desired results. All of these factors may negatively affect your investment in the Fund and you could lose money. Investment in the underlying funds also involves derivatives, counterparty, leverage, real estate-related, and commodity-linked investment risks. Counterparty Risk. Certain derivative and “over-the-counter” instruments, such as swaps and forwards, are subject to the risk that the other party to a contract will not fulfill its contractual obligations. Commodity-Linked Investments Risk. Certain underlying funds may invest in derivatives that have exposure to the commodities markets. Such exposure may subject an underlying fund to greater volatility than investments in traditional securities. The value of a commodity-linked derivative investment typically is based upon the price movements of a physical commodity (such as heating oil, livestock, or agricultural products), a commodity futures contract or commodity index, or some other readily measurable economic variable. The value of commodity-linked derivative instruments may therefore be affected by changes in overall market movements, volatility of the underlying benchmark, changes in interest rates, or other factors affecting a particular industry or commodity such as drought, floods, weather, livestock disease, embargoes, tariffs, and international economic, political, and regulatory developments. Derivatives Risk. Certain underlying funds may invest in derivatives. Derivatives can be highly volatile and involve risks in addition to the risks of the underlying referenced securities. Gains or losses from a derivative investment can be substantially greater than the derivative’s original cost, and can therefore involve leverage. Leverage may cause an underlying fund to be more volatile than if it had not used leverage. Derivatives can be less liquid than other types of investments and entail the risk that the counterparty will default on its payment obligations. Exchange-Traded Funds Risk. Certain underlying funds may purchase shares of exchange-traded funds (“ETFs”) to gain exposure to a particular portion of the market. ETFs are pooled investment vehicles, which may be managed or unmanaged, that generally seek to track the performance of a specific index. ETFs are traded on an exchange at market prices that may vary from the net asset value of their underlying investments. When an underlying fund invests in an ETF, in addition to directly bearing the expenses associated with its own operations, it will bear a pro rata portion of the ETF’s expenses. ETFs have certain inherent risks generally associated with investments in a portfolio of securities in which the ETF is invested, including the risk that the general level of stock prices may decline, thereby adversely affecting the value of each unit of the ETF. ETFs also involve the risk that an active trading market for an ETF’s shares may not develop or be maintained. Exchange-Traded Notes Risk. Certain underlying funds may invest in exchange-traded notes (“ETNs”), which are debt securities whose returns are linked to a particular index. ETNs are typically linked to the performance of a commodities index that reflects the potential return on unleveraged investments in futures contracts of physical commodities, plus a specified rate of interest that could be earned on cash collateral. ETNs are subject to credit risk and counterparty risk. The value of an ETN may vary and may be influenced by time to maturity, level of supply and demand for the ETN, volatility and lack of liquidity in underlying commodities markets, changes in the applicable interest rates, changes in the issuer’s credit rating, and economic, legal, political, or geographic events that affect the referenced commodity. When an underlying fund invests in ETNs it will bear its proportionate share of any fees and expenses borne by the ETN. There may be restrictions on an underlying fund’s right to redeem its investment in an ETN, which is meant to be held until maturity. An underlying fund’s decision to sell its ETN holdings may be limited by the availability of a secondary market. An investment in the Fund is not a bank deposit and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency.
Risk Lose Money [Text]	rr_RiskLoseMoney	The biggest risk is that the Fund’s returns will vary, and you could lose money.
Risk Not Insured Depository Institution [Text]	rr_RiskNotInsuredDepositoryInstitution	An investment in the Fund is not a bank deposit and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency.
Bar Chart and Performance Table [Heading]	rr_BarChartAndPerformanceTableHeading	PERFORMANCE INFORMATION
Performance Narrative [Text Block]	rr_PerformanceNarrativeTextBlock	The following information provides some indication of the risks of investing in the Fund by showing how the Fund’s performance has varied over time. Class T Shares (formerly named Class J Shares, the initial share class) of the Fund commenced operations with the Fund’s inception. Class A Shares, Class C Shares, Class S Shares, and Class I Shares of the Fund commenced operations on July 6, 2009. The performance shown for Class T Shares is calculated using the fees and expenses of Class T Shares in effect during the periods shown, net of any applicable fee and expense limitations or waivers. The performance shown for Class A Shares, Class C Shares, Class S Shares, and Class I Shares for periods prior to July 6, 2009, reflects the performance of the Fund’s former Class J Shares, calculated using the fees and expenses of each respective share class, without the effect of any fee and expense limitations or waivers. If Class A Shares, Class C Shares, Class S Shares, and Class I Shares of the Fund had been available during periods prior to July 6, 2009, the performance shown for each respective share class may have been different. The performance shown for periods following the Fund’s commencement of Class A Shares, Class C Shares, Class S Shares, and Class I Shares reflects the fees and expenses of each respective share class, net of any applicable fee and expense limitations or waivers. The bar chart depicts the change in performance from year to year during the periods indicated. Performance information for each underlying fund is available in its prospectus and/or the most recent annual or semiannual report. The bar chart figures do not include any applicable sales charges that an investor may pay when they buy or sell Class A Shares or Class C Shares of the Fund. If sales charges were included, the returns would be lower. The table compares the Fund’s average annual returns for the periods indicated to broad-based securities market indices. The indices are not actively managed and are not available for direct investment. All figures assume reinvestment of dividends and distributions. For certain periods, the Fund’s performance reflects the effect of expense waivers. Without the effect of these expense waivers, the performance shown would have been lower. The Fund’s past performance (before and after taxes) does not necessarily indicate how it will perform in the future. Updated performance information is available at janus.com/advisor/mutual-funds or by calling 1-877-335-2687.
Performance Information Illustrates Variability of Returns [Text]	rr_PerformanceInformationIllustratesVariabilityOfReturns	The following information provides some indication of the risks of investing in the Fund by showing how the Fund’s performance has varied over time. The bar chart depicts the change in performance from year to year during the periods indicated.
Performance Additional Market Index [Text]	rr_PerformanceAdditionalMarketIndex	The table compares the Fund’s average annual returns for the periods indicated to broad-based securities market indices. The indices are not actively managed and are not available for direct investment. All figures assume reinvestment of dividends and distributions.
Performance Availability Phone [Text]	rr_PerformanceAvailabilityPhone	1-877-335-2687
Performance Availability Website Address [Text]	rr_PerformanceAvailabilityWebSiteAddress	janus.com/advisor/mutual-funds
Performance Past Does Not Indicate Future [Text]	rr_PerformancePastDoesNotIndicateFuture	The Fund’s past performance (before and after taxes) does not necessarily indicate how it will perform in the future.
Bar Chart [Heading]	rr_BarChartHeading	Annual Total Returns for Class T Shares (calendar year-end)
Bar Chart Does Not Reflect Sales Loads [Text]	rr_BarChartDoesNotReflectSalesLoads	The bar chart figures do not include any applicable sales charges that an investor may pay when they buy or sell Class A Shares or Class C Shares of the Fund. If sales charges were included, the returns would be lower.
Bar Chart Closing [Text Block]	rr_BarChartClosingTextBlock	Best Quarter:  Second Quarter 2009  10.64%          Worst Quarter:  Third Quarter 2008  −6.58%
Year to Date Return, Label	rr_YearToDateReturnLabel	The Fund’s year-to-date return as of the calendar quarter ended September 30, 2013 was 6.61%.
Performance Table Heading	rr_PerformanceTableHeading	Average Annual Total Returns (periods ended 12/31/12)
Performance Table Uses Highest Federal Rate	rr_PerformanceTableUsesHighestFederalRate	After-tax returns are calculated using the historically highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes.
Performance Table Not Relevant to Tax Deferred	rr_PerformanceTableNotRelevantToTaxDeferred	Actual after-tax returns depend on your individual tax situation and may differ from those shown in the preceding table. The after-tax return information shown above does not apply to Fund shares held through a tax-deferred account, such as a 401(k) plan or an IRA.
Performance Table One Class of after Tax Shown [Text]	rr_PerformanceTableOneClassOfAfterTaxShown	After-tax returns are only shown for Class T Shares of the Fund. After-tax returns for the other classes of Shares will vary from those shown for Class T Shares due to varying sales charges (as applicable), fees, and expenses among the classes.
Performance Table Narrative	rr_PerformanceTableNarrativeTextBlock	Effective February 15, 2013, the Fund’s primary benchmark index changed from the S&P 500® Index to the Barclays Global Aggregate Bond Index to reflect the global investment strategies of the Fund. Additionally, the Fund changed the name of its secondary benchmark index from Conservative Allocation Index to Global Conservative Allocation Index and its composition from an internally-calculated, hypothetical combination of unmanaged indices that combines total returns from the Barclays U.S. Aggregate Bond Index (60%), the Dow Jones Wilshire 5000 Index (28%), and the Morgan Stanley Capital International Europe, Australasia, Far East Index (“MSCI EAFE®”) Index (12%) to an internally-calculated, hypothetical combination of unmanaged indices that combines total returns from the Barclays Global Aggregate Bond Index (60%) and the Morgan Stanley Capital International All Country World IndexSM (40%). The Barclays Global Aggregate Bond Index is an index that provides a broad-based measure of the global investment grade fixed-rate debt markets. Janus Capital believes that the foregoing benchmark index changes provide a more appropriate representation of the Fund’s revised investment strategy that includes an increased focus on global investments, including emerging markets. After-tax returns are calculated using distributions for the Fund’s Class T Shares (formerly named Class J Shares, the initial share class). After-tax returns are calculated using the historically highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes. Actual after-tax returns depend on your individual tax situation and may differ from those shown in the preceding table. The after-tax return information shown above does not apply to Fund shares held through a tax-deferred account, such as a 401(k) plan or an IRA. After-tax returns are only shown for Class T Shares of the Fund. After-tax returns for the other classes of Shares will vary from those shown for Class T Shares due to varying sales charges (as applicable), fees, and expenses among the classes.
Performance Table Closing [Text Block]	rr_PerformanceTableClosingTextBlock	Updated performance information is available at janus.com/advisor/mutual-funds or by calling 1-877-335-2687.
Janus Global Allocation Fund - Conservative | Class A, C, S, I, T Shares | Class A
Risk/Return:	rr_RiskReturnAbstract
Shareholder Fees Column [Text]	rr_ShareholderFeesColumnName	Class A
Maximum Sales Charge (load) Imposed on Purchases (as a percentage of offering price)	rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice	5.75%
Maximum Deferred Sales Charge (load) (as a percentage of the lower of original purchase price or redemption proceeds)	rr_MaximumDeferredSalesChargeOverOther	none
Operating Expenses Column [Text]	rr_OperatingExpensesColumnName	Class A
Management Fees	rr_ManagementFeesOverAssets	0.05%
Distribution/Service (12b-1) Fees	rr_DistributionAndService12b1FeesOverAssets	0.25%
Other Expenses	rr_OtherExpensesOverAssets	0.13%
Acquired Fund Fees and Expenses	rr_AcquiredFundFeesAndExpensesOverAssets	0.60%
Total Annual Fund Operating Expenses	rr_ExpensesOverAssets	1.03%
Expense Example, By Year, Column [Text]	rr_ExpenseExampleByYearColumnName	Class A Shares
1 Year	rr_ExpenseExampleYear01	674
3 Years	rr_ExpenseExampleYear03	884
5 Years	rr_ExpenseExampleYear05	1,111
10 Years	rr_ExpenseExampleYear10	1,762
Expense Example, No Redemption, By Year, Column [Text]	rr_ExpenseExampleNoRedemptionByYearColumnName	Class A Shares
1 Year	rr_ExpenseExampleNoRedemptionYear01	674
3 Years	rr_ExpenseExampleNoRedemptionYear03	884
5 Years	rr_ExpenseExampleNoRedemptionYear05	1,111
10 Years	rr_ExpenseExampleNoRedemptionYear10	1,762
Janus Global Allocation Fund - Conservative | Class A, C, S, I, T Shares | Class C
Risk/Return:	rr_RiskReturnAbstract
Shareholder Fees Column [Text]	rr_ShareholderFeesColumnName	Class C
Maximum Sales Charge (load) Imposed on Purchases (as a percentage of offering price)	rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice	none
Maximum Deferred Sales Charge (load) (as a percentage of the lower of original purchase price or redemption proceeds)	rr_MaximumDeferredSalesChargeOverOther	1.00%
Operating Expenses Column [Text]	rr_OperatingExpensesColumnName	Class C
Management Fees	rr_ManagementFeesOverAssets	0.05%
Distribution/Service (12b-1) Fees	rr_DistributionAndService12b1FeesOverAssets	1.00%
Other Expenses	rr_OtherExpensesOverAssets	0.14%
Acquired Fund Fees and Expenses	rr_AcquiredFundFeesAndExpensesOverAssets	0.60%
Total Annual Fund Operating Expenses	rr_ExpensesOverAssets	1.79%
Expense Example, By Year, Column [Text]	rr_ExpenseExampleByYearColumnName	Class C Shares
1 Year	rr_ExpenseExampleYear01	282
3 Years	rr_ExpenseExampleYear03	563
5 Years	rr_ExpenseExampleYear05	970
10 Years	rr_ExpenseExampleYear10	2,105
Expense Example, No Redemption, By Year, Column [Text]	rr_ExpenseExampleNoRedemptionByYearColumnName	Class C Shares
1 Year	rr_ExpenseExampleNoRedemptionYear01	182
3 Years	rr_ExpenseExampleNoRedemptionYear03	563
5 Years	rr_ExpenseExampleNoRedemptionYear05	970
10 Years	rr_ExpenseExampleNoRedemptionYear10	2,105
Janus Global Allocation Fund - Conservative | Class A, C, S, I, T Shares | Class S
Risk/Return:	rr_RiskReturnAbstract
Shareholder Fees Column [Text]	rr_ShareholderFeesColumnName	Class S
Maximum Sales Charge (load) Imposed on Purchases (as a percentage of offering price)	rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice	none
Maximum Deferred Sales Charge (load) (as a percentage of the lower of original purchase price or redemption proceeds)	rr_MaximumDeferredSalesChargeOverOther	none
Operating Expenses Column [Text]	rr_OperatingExpensesColumnName	Class S
Management Fees	rr_ManagementFeesOverAssets	0.05%
Distribution/Service (12b-1) Fees	rr_DistributionAndService12b1FeesOverAssets	0.25%
Other Expenses	rr_OtherExpensesOverAssets	0.31%
Acquired Fund Fees and Expenses	rr_AcquiredFundFeesAndExpensesOverAssets	0.60%
Total Annual Fund Operating Expenses	rr_ExpensesOverAssets	1.21%
Expense Example, By Year, Column [Text]	rr_ExpenseExampleByYearColumnName	Class S Shares
1 Year	rr_ExpenseExampleYear01	123
3 Years	rr_ExpenseExampleYear03	384
5 Years	rr_ExpenseExampleYear05	665
10 Years	rr_ExpenseExampleYear10	1,466
Expense Example, No Redemption, By Year, Column [Text]	rr_ExpenseExampleNoRedemptionByYearColumnName	Class S Shares
1 Year	rr_ExpenseExampleNoRedemptionYear01	123
3 Years	rr_ExpenseExampleNoRedemptionYear03	384
5 Years	rr_ExpenseExampleNoRedemptionYear05	665
10 Years	rr_ExpenseExampleNoRedemptionYear10	1,466
Janus Global Allocation Fund - Conservative | Class A, C, S, I, T Shares | Class I
Risk/Return:	rr_RiskReturnAbstract
Shareholder Fees Column [Text]	rr_ShareholderFeesColumnName	Class I
Maximum Sales Charge (load) Imposed on Purchases (as a percentage of offering price)	rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice	none
Maximum Deferred Sales Charge (load) (as a percentage of the lower of original purchase price or redemption proceeds)	rr_MaximumDeferredSalesChargeOverOther	none
Operating Expenses Column [Text]	rr_OperatingExpensesColumnName	Class I
Management Fees	rr_ManagementFeesOverAssets	0.05%
Distribution/Service (12b-1) Fees	rr_DistributionAndService12b1FeesOverAssets	none
Other Expenses	rr_OtherExpensesOverAssets	0.15%
Acquired Fund Fees and Expenses	rr_AcquiredFundFeesAndExpensesOverAssets	0.60%
Total Annual Fund Operating Expenses	rr_ExpensesOverAssets	0.80%
Expense Example, By Year, Column [Text]	rr_ExpenseExampleByYearColumnName	Class I Shares
1 Year	rr_ExpenseExampleYear01	82
3 Years	rr_ExpenseExampleYear03	255
5 Years	rr_ExpenseExampleYear05	444
10 Years	rr_ExpenseExampleYear10	990
Expense Example, No Redemption, By Year, Column [Text]	rr_ExpenseExampleNoRedemptionByYearColumnName	Class I Shares
1 Year	rr_ExpenseExampleNoRedemptionYear01	82
3 Years	rr_ExpenseExampleNoRedemptionYear03	255
5 Years	rr_ExpenseExampleNoRedemptionYear05	444
10 Years	rr_ExpenseExampleNoRedemptionYear10	990
Janus Global Allocation Fund - Conservative | Class A, C, S, I, T Shares | Class T
Risk/Return:	rr_RiskReturnAbstract
Shareholder Fees Column [Text]	rr_ShareholderFeesColumnName	Class T
Maximum Sales Charge (load) Imposed on Purchases (as a percentage of offering price)	rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice	none
Maximum Deferred Sales Charge (load) (as a percentage of the lower of original purchase price or redemption proceeds)	rr_MaximumDeferredSalesChargeOverOther	none
Operating Expenses Column [Text]	rr_OperatingExpensesColumnName	Class T
Management Fees	rr_ManagementFeesOverAssets	0.05%
Distribution/Service (12b-1) Fees	rr_DistributionAndService12b1FeesOverAssets	none
Other Expenses	rr_OtherExpensesOverAssets	0.31%
Acquired Fund Fees and Expenses	rr_AcquiredFundFeesAndExpensesOverAssets	0.60%
Total Annual Fund Operating Expenses	rr_ExpensesOverAssets	0.96%
Expense Example, By Year, Column [Text]	rr_ExpenseExampleByYearColumnName	Class T Shares
1 Year	rr_ExpenseExampleYear01	98
3 Years	rr_ExpenseExampleYear03	306
5 Years	rr_ExpenseExampleYear05	531
10 Years	rr_ExpenseExampleYear10	1,178
Expense Example, No Redemption, By Year, Column [Text]	rr_ExpenseExampleNoRedemptionByYearColumnName	Class T Shares
1 Year	rr_ExpenseExampleNoRedemptionYear01	98
3 Years	rr_ExpenseExampleNoRedemptionYear03	306
5 Years	rr_ExpenseExampleNoRedemptionYear05	531
10 Years	rr_ExpenseExampleNoRedemptionYear10	$ 1,178
2006	rr_AnnualReturn2006	11.09%
2007	rr_AnnualReturn2007	10.19%
2008	rr_AnnualReturn2008	(16.01%)
2009	rr_AnnualReturn2009	23.37%
2010	rr_AnnualReturn2010	10.60%
2011	rr_AnnualReturn2011	1.39%
2012	rr_AnnualReturn2012	10.82%
Bar Chart, Year to Date Return, Date	rr_BarChartYearToDateReturnDate	Sep. 30, 2013
Bar Chart, Year to Date Return	rr_BarChartYearToDateReturn	6.61%
Highest Quarterly Return, Label	rr_HighestQuarterlyReturnLabel	Best Quarter:
Highest Quarterly Return, Date	rr_BarChartHighestQuarterlyReturnDate	Jun. 30, 2009
Highest Quarterly Return	rr_BarChartHighestQuarterlyReturn	10.64%
Lowest Quarterly Return, Label	rr_LowestQuarterlyReturnLabel	Worst Quarter:
Lowest Quarterly Return, Date	rr_BarChartLowestQuarterlyReturnDate	Sep. 30, 2008
Lowest Quarterly Return	rr_BarChartLowestQuarterlyReturn	(6.58%)
Janus Global Allocation Fund - Conservative | Class A, C, S, I, T Shares | Return Before Taxes | Class A
Risk/Return:	rr_RiskReturnAbstract
Column	rr_AverageAnnualReturnColumnName	Class A Shares
Label	rr_AverageAnnualReturnLabel	Return Before Taxes	[1]
1 Year	rr_AverageAnnualReturnYear01	4.20%
5 Years	rr_AverageAnnualReturnYear05	3.81%
Since Inception	rr_AverageAnnualReturnSinceInception	5.63%
Inception Date	rr_AverageAnnualReturnInceptionDate	Dec. 30, 2005
Janus Global Allocation Fund - Conservative | Class A, C, S, I, T Shares | Return Before Taxes | Class C
Risk/Return:	rr_RiskReturnAbstract
Column	rr_AverageAnnualReturnColumnName	Class C Shares
Label	rr_AverageAnnualReturnLabel	Return Before Taxes	[2]
1 Year	rr_AverageAnnualReturnYear01	8.70%
5 Years	rr_AverageAnnualReturnYear05	4.28%
Since Inception	rr_AverageAnnualReturnSinceInception	5.75%
Inception Date	rr_AverageAnnualReturnInceptionDate	Dec. 30, 2005
Janus Global Allocation Fund - Conservative | Class A, C, S, I, T Shares | Return Before Taxes | Class S
Risk/Return:	rr_RiskReturnAbstract
Column	rr_AverageAnnualReturnColumnName	Class S Shares
Label	rr_AverageAnnualReturnLabel	Return Before Taxes
1 Year	rr_AverageAnnualReturnYear01	10.42%
5 Years	rr_AverageAnnualReturnYear05	4.78%
Since Inception	rr_AverageAnnualReturnSinceInception	6.27%
Inception Date	rr_AverageAnnualReturnInceptionDate	Dec. 30, 2005
Janus Global Allocation Fund - Conservative | Class A, C, S, I, T Shares | Return Before Taxes | Class I
Risk/Return:	rr_RiskReturnAbstract
Column	rr_AverageAnnualReturnColumnName	Class I Shares
Label	rr_AverageAnnualReturnLabel	Return Before Taxes
1 Year	rr_AverageAnnualReturnYear01	10.92%
5 Years	rr_AverageAnnualReturnYear05	5.19%
Since Inception	rr_AverageAnnualReturnSinceInception	6.71%
Inception Date	rr_AverageAnnualReturnInceptionDate	Dec. 30, 2005
Janus Global Allocation Fund - Conservative | Class A, C, S, I, T Shares | Return Before Taxes | Class T
Risk/Return:	rr_RiskReturnAbstract
Column	rr_AverageAnnualReturnColumnName	Class T Shares
Label	rr_AverageAnnualReturnLabel	Return Before Taxes
1 Year	rr_AverageAnnualReturnYear01	10.82%
5 Years	rr_AverageAnnualReturnYear05	5.19%
Since Inception	rr_AverageAnnualReturnSinceInception	6.71%
Inception Date	rr_AverageAnnualReturnInceptionDate	Dec. 30, 2005
Janus Global Allocation Fund - Conservative | Class A, C, S, I, T Shares | Return After Taxes on Distributions | Class T
Risk/Return:	rr_RiskReturnAbstract
Column	rr_AverageAnnualReturnColumnName	Class T Shares
Label	rr_AverageAnnualReturnLabel	Return After Taxes on Distributions
1 Year	rr_AverageAnnualReturnYear01	9.91%
5 Years	rr_AverageAnnualReturnYear05	4.14%
Since Inception	rr_AverageAnnualReturnSinceInception	5.69%
Inception Date	rr_AverageAnnualReturnInceptionDate	Dec. 30, 2005
Janus Global Allocation Fund - Conservative | Class A, C, S, I, T Shares | Return After Taxes on Distributions and Sale of Fund Shares | Class T
Risk/Return:	rr_RiskReturnAbstract
Column	rr_AverageAnnualReturnColumnName	Class T Shares
Label	rr_AverageAnnualReturnLabel	Return After Taxes on Distributions and Sale of Fund Shares
1 Year	rr_AverageAnnualReturnYear01	7.17%
5 Years	rr_AverageAnnualReturnYear05	3.85%
Since Inception	rr_AverageAnnualReturnSinceInception	5.23%
Inception Date	rr_AverageAnnualReturnInceptionDate	Dec. 30, 2005
Janus Global Allocation Fund - Conservative | Class A, C, S, I, T Shares | Barclays Global Aggregate Bond Index (reflects no deduction for expenses, fees, or taxes)
Risk/Return:	rr_RiskReturnAbstract
Label	rr_AverageAnnualReturnLabel	Barclays Global Aggregate Bond Index
1 Year	rr_AverageAnnualReturnYear01	4.32%
5 Years	rr_AverageAnnualReturnYear05	5.44%
Since Inception	rr_AverageAnnualReturnSinceInception	6.18%
Inception Date	rr_AverageAnnualReturnInceptionDate	Dec. 30, 2005
Janus Global Allocation Fund - Conservative | Class A, C, S, I, T Shares | Global Conservative Allocation Index (reflects no deduction for expenses, fees, or taxes, except any applicable foreign withholding taxes)
Risk/Return:	rr_RiskReturnAbstract
Label	rr_AverageAnnualReturnLabel	Global Conservative Allocation Index
1 Year	rr_AverageAnnualReturnYear01	9.09%
5 Years	rr_AverageAnnualReturnYear05	3.22%
Since Inception	rr_AverageAnnualReturnSinceInception	5.48%
Inception Date	rr_AverageAnnualReturnInceptionDate	Dec. 30, 2005
Janus Global Allocation Fund - Conservative | Class A, C, S, I, T Shares | S&P 500® Index (reflects no deduction for expenses, fees, or taxes)
Risk/Return:	rr_RiskReturnAbstract
Label	rr_AverageAnnualReturnLabel	S&P 500® Index
1 Year	rr_AverageAnnualReturnYear01	16.00%
5 Years	rr_AverageAnnualReturnYear05	1.66%
Since Inception	rr_AverageAnnualReturnSinceInception	4.12%
Inception Date	rr_AverageAnnualReturnInceptionDate	Dec. 30, 2005
Janus Global Allocation Fund - Conservative | Class A, C, S, I, T Shares | Conservative Allocation Index (reflects no deduction for expenses, fees, or taxes, except any applicable foreign withholding taxes)
Risk/Return:	rr_RiskReturnAbstract
Label	rr_AverageAnnualReturnLabel	Conservative Allocation Index
1 Year	rr_AverageAnnualReturnYear01	9.21%
5 Years	rr_AverageAnnualReturnYear05	4.26%
Since Inception	rr_AverageAnnualReturnSinceInception	5.49%
Inception Date	rr_AverageAnnualReturnInceptionDate	Dec. 30, 2005

[1] Calculated assuming maximum permitted sales loads.

[2] The one year return is calculated to include the contingent deferred sales charge.

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Janus Global Allocation Fund - Moderate | Class D Shares

FUND SUMMARY

Janus Global Allocation Fund – Moderate
(formerly named Janus Moderate Allocation Fund)

INVESTMENT OBJECTIVE

Janus Global Allocation Fund – Moderate seeks total return through growth of capital and income.

FEES AND EXPENSES OF THE FUND

This table describes the fees and expenses that you may pay if you buy and hold Shares of the Fund.

ANNUAL FUND OPERATING EXPENSES
(expenses that you pay each year as a percentage of the value of your investment)

Annual Fund Operating Expenses	Janus Global Allocation Fund - Moderate Class D Shares Class D
Operating Expenses Column [Text]	Class D
Management Fees	0.05%
Other Expenses	0.20%
Acquired Fund Fees and Expenses	0.65%
Total Annual Fund Operating Expenses	0.90%

EXAMPLE:

The Example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds.

The Example assumes that you invest $10,000 in the Fund for the time periods indicated, reinvest all dividends and distributions, and then redeem all of your Shares at the end of each period. The Example also assumes that your investment has a 5% return each year and that the Fund’s operating expenses (including the operating expenses of the underlying funds) remain the same. Although your actual costs may be higher or lower, based on these assumptions your costs would be:

Expense Example (USD $)	Expense Example, By Year, Column [Text]	1 Year	3 Years	5 Years	10 Years
Janus Global Allocation Fund - Moderate Class D Shares Class D	Class D Shares	92	287	498	1,108

Portfolio Turnover: 

The Fund pays transaction costs, such as commissions, when it buys and sells securities (or “turns over” its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when Fund shares are held in a taxable account. These costs, which are not reflected in annual fund operating expenses or in the Example, affect the Fund’s performance. During the most recent fiscal year, the Fund’s portfolio turnover rate was 64% of the average value of its portfolio.

PRINCIPAL INVESTMENT STRATEGIES

The Fund seeks to achieve its investment objective by investing in other Janus mutual funds (“underlying funds”) that represent a variety of asset classes and investment styles and provide exposure to issuers that are economically tied to countries throughout the world. Through its investments in underlying funds, the Fund invests in issuers from several different countries and may, under unusual circumstances, be invested in a single country. As a result, the Fund normally will have approximately 40% of its net assets allocated to non-U.S. investments. The Fund may also have significant exposure to emerging markets.

The Fund pursues this objective by investing in a diversified portfolio of underlying funds, resulting in an allocation of the Fund’s investments that normally provides exposure of approximately 55% to equity investments, 35% to fixed-income securities and money market instruments, and 10% to alternative investments. The target allocation and the allocation of the Fund’s assets among underlying funds are based on quantitative and qualitative analysis. Because it invests in other funds, the Fund is considered a “fund of funds.”

The Fund’s asset allocation is intended to diversify investments throughout the world among equity investments, fixed-income securities, cash equivalents, and alternative investments. The portfolio manager determines the overall composition of the Fund, oversees the investment process, and is responsible for the day-to-day management of the Fund. The portfolio manager continually monitors asset class allocations and periodically rebalances the Fund’s investments in the underlying funds. The portfolio manager also regularly reviews the allocation of Fund assets in the underlying funds and may modify the underlying funds’ weightings or substitute other underlying funds to emphasize and mitigate risk exposures that may arise as a result of the implementation of the allocations. An independent asset allocation service provides evaluations of asset allocations that the portfolio manager may use in implementing the allocations among the underlying funds.

Additionally, the portfolio manager consults with a committee (the “Janus Global Allocation Committee”) to regularly review the broad market, macroeconomic conditions and other global financial factors that may impact the Fund’s allocation of assets among the underlying funds and asset classes. The Janus Global Allocation Committee is comprised of investment professionals of Janus Capital and may also include investment professionals of Janus Capital’s affiliated investment advisers. The portfolio manager and Janus Global Allocation Committee normally meet on a quarterly basis. The portfolio manager may change the Fund’s asset class allocations, the underlying funds, an underlying fund’s asset category, or weightings among asset classes or underlying funds without prior shareholder notice.

The Fund will normally allocate approximately 55% of its investments to underlying funds that provide varying exposure to common stocks of large U.S.-based companies, small- to mid-capitalization companies, and international companies (including those with exposure to emerging markets), approximately 35% of its investments to underlying bond funds and money market instruments, and approximately 10% of its investments to underlying funds that seek returns uncorrelated with the returns of stocks and bonds by providing exposure to alternative investments and alternative investment strategies. Refer to Appendix A in this Prospectus for a brief description of the investment strategies of each of the currently available underlying funds.

When market conditions dictate a more defensive strategy, the Fund or an underlying fund may temporarily hold cash or invest its assets in temporary investments. In that case, the Fund may take positions that are inconsistent with its investment objective. As a result, the Fund may not achieve its investment objective.

PRINCIPAL INVESTMENT RISKS

The biggest risk is that the Fund’s returns will vary, and you could lose money. The Fund is designed for long-term investors seeking growth of capital and income. Investments in a portfolio with common stock and alternative investment exposure tend to be more volatile than many other investment choices.

Main Risks Associated with the Fund
Allocation Risk. The Fund’s ability to achieve its investment objective depends largely upon the portfolio manager’s allocation of assets among the underlying funds and other securities, using the optimization process (a process that utilizes quantitative analysis of a number of factors, such as historical risk, performance, fund classifications, and the relationship among underlying funds) and the judgment of the portfolio manager. You could lose money on your investment in the Fund as a result of these allocations. The Fund will typically invest in a number of different underlying funds; however, to the extent that the Fund invests a significant portion of its assets in a single underlying fund, it will be more sensitive to the risks associated with that fund and any investments in which that fund focuses.

Affiliated Fund Risk. Janus Capital has the authority to select and substitute underlying affiliated mutual funds. The fees paid to Janus Capital by some Janus mutual funds are generally higher than the fees paid to Janus Capital by the Fund or by other funds and share classes available for investment by the Fund. These conditions may create a conflict of interest when selecting underlying affiliated mutual funds and share classes for investment. Janus Capital, however, is a fiduciary to the Fund and its shareholders and is legally obligated to act in their best interest when selecting underlying affiliated mutual funds.

Main Risks Associated with the Underlying Funds and Securities
The biggest risk is that the underlying funds’ returns will vary, and you could lose money.

Market Risk. Approximately 55% of the Fund’s assets are allocated to equity investments through investments in underlying funds. The value of an underlying fund’s portfolio may decrease if the value of an individual company or security, or multiple companies or securities, in the portfolio decreases or if a portfolio manager’s belief about a company’s intrinsic worth is incorrect. Further, regardless of how well individual companies or securities perform, the value of an underlying fund’s portfolio could also decrease if there are deteriorating economic or market conditions. It is important to understand that the value of your investment may fall, sometimes sharply, in response to changes in the market, and you could lose money.

Fixed-Income Securities Risk. Approximately 35% of the Fund’s assets are allocated to fixed-income securities through investments in underlying funds. Typically, the values of fixed-income securities change inversely with prevailing interest rates. Therefore, a fundamental risk of fixed-income securities is interest rate risk, which is the risk that the value of such securities will generally decline as prevailing interest rates rise, which may cause an underlying fund’s net asset value to likewise decrease. How specific fixed-income securities may react to changes in interest rates will depend on the specific characteristics of each security. Fixed-income securities are also subject to credit risk, prepayment risk, valuation risk, and liquidity risk. Credit risk is the risk that the credit strength of an issuer of a fixed-income security will weaken and/or that the issuer will be unable to make timely principal and interest payments and that the security may go into default. Prepayment risk is the risk that during periods of falling interest rates, certain fixed-income securities with higher interest rates, such as mortgage- and asset-backed securities, may be prepaid by their issuers thereby reducing the amount of interest payments. Valuation risk is the risk that one or more of the fixed-income securities in which an underlying fund invests are priced differently than the value realized upon such security’s sale. In times of market instability, valuation may be more difficult. Liquidity risk is the risk that fixed-income securities may be difficult or impossible to sell at the time that an underlying fund’s portfolio manager would like or at the price the portfolio manager believes the security is currently worth.

Foreign Exposure Risk. Certain underlying funds may have significant exposure to foreign markets as a result of their investments in foreign securities, including investments in emerging markets, which can be more volatile than the U.S. markets. As a result, an underlying fund’s returns and net asset value may be affected to a large degree by fluctuations in currency exchange rates or political or economic conditions in a particular country. A market swing in one or more countries or regions where an underlying fund has invested a significant amount of its assets may have a greater effect on an underlying fund’s performance than it would in a more geographically diversified portfolio. An underlying fund’s investments in emerging market countries may involve risks greater than, or in addition to, the risks of investing in more developed countries.

Emerging Markets Risk. The risks of foreign investing mentioned above are heightened when investing in emerging markets. Emerging markets securities involve a number of additional risks, which may result from less government supervision and regulation of business and industry practices (including the potential lack of strict finance and accounting controls and standards), stock exchanges, brokers, and listed companies, making these investments potentially more volatile in price and less liquid than investments in developed securities markets, resulting in greater risk to investors. In addition, an underlying fund’s investments may be denominated in foreign currencies and therefore, changes in the value of a country’s currency compared to the U.S. dollar may affect the value of an underlying fund’s investments. To the extent that an underlying fund invests a significant portion of its assets in the securities of issuers in or companies of a single country or region, it is more likely to be impacted by events or conditions affecting that country or region, which could have a negative impact on the Fund’s performance. Some of the risks of investing directly in foreign and emerging market securities may be reduced when an underlying fund invests indirectly in foreign securities through various other investment vehicles including derivatives, which also involve other risks.

Sovereign Debt Risk. An underlying fund may invest in U.S. and foreign government debt securities (“sovereign debt”). Investments in U.S. sovereign debt are considered low risk. However, investments in non-U.S. sovereign debt can involve a high degree of risk, including the risk that the governmental entity that controls the repayment of sovereign debt may not be willing or able to repay the principal and/or to pay the interest on its sovereign debt in a timely manner. A sovereign debtor’s willingness or ability to satisfy its debt obligation may be affected by various factors including, but not limited to, its cash flow situation, the extent of its foreign currency reserves, the availability of foreign exchange when a payment is due, and the relative size of its debt position in relation to its economy as a whole. In the event of default, there may be limited or no legal remedies for collecting sovereign debt and there may be no bankruptcy proceedings through which the underlying fund may collect all or part of the sovereign debt that a governmental entity has not repaid.

Mortgage-Backed Securities Risk. Mortgage-backed securities are classified generally as either commercial mortgage-backed securities or residential mortgage-backed securities, each of which is subject to certain specific risks. Mortgage-backed securities tend to be more sensitive to changes in interest rates than other types of debt securities. Investments in mortgage-backed securities are subject to both extension risk, where borrowers extend the duration of their mortgages in times of rising interest rates, and prepayment risk, where borrowers pay off their mortgages sooner than expected in times of declining interest rates. These risks may reduce the Fund’s returns. In addition, investments in mortgage-backed securities, including those comprised of subprime mortgages, may be subject to a higher degree of credit risk, valuation risk, and liquidity risk than various other types of fixed-income securities.

Alternative Investments Allocation Risk. Approximately 10% of the Fund’s assets are allocated to alternative investments through investments in underlying funds that invest in alternative investment strategies. In connection with the Fund’s allocation to alternative investments, the Fund may invest in a Janus underlying fund, Janus Diversified Alternatives Fund, which seeks returns uncorrelated with the returns generated by investments in stocks and bonds. In addition, as part of its alternative investments allocation, the Fund may invest in Janus Global Real Estate Fund. Janus Diversified Alternatives Fund’s ability to achieve its investment objective depends largely upon the successful evaluation of the risk, potential returns, and correlation properties with respect to its investments. There is a risk that the returns provided by alternative investments may be subject to high volatility and that an underlying fund’s portfolio manager’s beliefs about the expected returns, risk and correlation properties of one or more of an underlying fund’s investments may be incorrect. There is also a risk that an underlying fund’s investments will correlate with the performance of stocks and bonds to a greater degree than anticipated. Janus Capital does not have prior experience managing the investment strategy of Janus Diversified Alternatives Fund, and there is no guarantee that the investment techniques and analysis used by the underlying fund’s portfolio managers will produce the desired results. All of these factors may negatively affect your investment in the Fund and you could lose money. Investment in the underlying funds also involves derivatives, counterparty, leverage, real estate-related, and commodity-linked investment risks.

Counterparty Risk. Certain derivative and “over-the-counter” instruments, such as swaps and forwards, are subject to the risk that the other party to a contract will not fulfill its contractual obligations.

Commodity-Linked Investments Risk. Certain underlying funds may invest in derivatives that have exposure to the commodities markets. Such exposure may subject an underlying fund to greater volatility than investments in traditional securities. The value of a commodity-linked derivative investment typically is based upon the price movements of a physical commodity (such as heating oil, livestock, or agricultural products), a commodity futures contract or commodity index, or some other readily measurable economic variable. The value of commodity-linked derivative instruments may therefore be affected by changes in overall market movements, volatility of the underlying benchmark, changes in interest rates, or other factors affecting a particular industry or commodity such as drought, floods, weather, livestock disease, embargoes, tariffs, and international economic, political, and regulatory developments.

Derivatives Risk. Certain underlying funds may invest in derivatives. Derivatives can be highly volatile and involve risks in addition to the risks of the underlying referenced securities. Gains or losses from a derivative investment can be substantially greater than the derivative’s original cost, and can therefore involve leverage. Leverage may cause an underlying fund to be more volatile than if it had not used leverage. Derivatives can be less liquid than other types of investments and entail the risk that the counterparty will default on its payment obligations.

Exchange-Traded Funds Risk. Certain underlying funds may purchase shares of exchange-traded funds (“ETFs”) to gain exposure to a particular portion of the market. ETFs are pooled investment vehicles, which may be managed or unmanaged, that generally seek to track the performance of a specific index. ETFs are traded on an exchange at market prices that may vary from the net asset value of their underlying investments. When an underlying fund invests in an ETF, in addition to directly bearing the expenses associated with its own operations, it will bear a pro rata portion of the ETF’s expenses. ETFs have certain inherent risks generally associated with investments in a portfolio of securities in which the ETF is invested, including the risk that the general level of stock prices may decline, thereby adversely affecting the value of each unit of the ETF. ETFs also involve the risk that an active trading market for an ETF’s shares may not develop or be maintained.

Exchange-Traded Notes Risk. Certain underlying funds may invest in exchange-traded notes (“ETNs”), which are debt securities whose returns are linked to a particular index. ETNs are typically linked to the performance of a commodities index that reflects the potential return on unleveraged investments in futures contracts of physical commodities, plus a specified rate of interest that could be earned on cash collateral. ETNs are subject to credit risk and counterparty risk. The value of an ETN may vary and may be influenced by time to maturity, level of supply and demand for the ETN, volatility and lack of liquidity in underlying commodities markets, changes in the applicable interest rates, changes in the issuer’s credit rating, and economic, legal, political, or geographic events that affect the referenced commodity. When an underlying fund invests in ETNs it will bear its proportionate share of any fees and expenses borne by the ETN. There may be restrictions on an underlying fund’s right to redeem its investment in an ETN, which is meant to be held until maturity. An underlying fund’s decision to sell its ETN holdings may be limited by the availability of a secondary market.

An investment in the Fund is not a bank deposit and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency.

PERFORMANCE INFORMATION

The following information provides some indication of the risks of investing in the Fund by showing how the Fund’s performance has varied over time. Class D Shares of the Fund commenced operations on February 16, 2010, as a result of the restructuring of Class J Shares, the predecessor share class. The performance shown for Class D Shares for periods prior to February 16, 2010, reflects the performance of the Fund’s former Class J Shares, calculated using the fees and expenses in effect during the periods shown, net of any applicable fee and expense limitations or waivers. If Class D Shares of the Fund had been available during periods prior to February 16, 2010, the performance shown may have been different. The performance shown for periods following the Fund’s commencement of Class D Shares reflects the fees and expenses of Class D Shares, net of any applicable fee and expense limitations or waivers.

The bar chart depicts the change in performance from year to year during the periods indicated. Performance information for each underlying fund is available in its prospectus and/or the most recent annual or semiannual report. The table compares the Fund’s average annual returns for the periods indicated to broad-based securities market indices. The indices are not actively managed and are not available for direct investment. All figures assume reinvestment of dividends and distributions. For certain periods, the Fund’s performance reflects the effect of expense waivers. Without the effect of these expense waivers, the performance shown would have been lower.

The Fund’s past performance (before and after taxes) does not necessarily indicate how it will perform in the future. Updated performance information is available at janus.com/allfunds or by calling 1-800-525-3713.

Annual Total Returns for Class D Shares (calendar year-end)

Best Quarter:  Second Quarter 2009  14.27%          Worst Quarter:  Fourth Quarter 2008  −11.62%

The Fund’s year-to-date return as of the calendar quarter ended September 30, 2013 was 9.53%.

Average Annual Total Returns (periods ended 12/31/12)

Average Annual Total Returns Janus Global Allocation Fund - Moderate Class D Shares	Column	Label	1 Year	5 Years	Since Inception	Inception Date
Class D Return Before Taxes	Class D Shares	Return Before Taxes	12.74%	3.74%	6.44%	Dec. 30, 2005
Class D Return After Taxes on Distributions	Class D Shares	Return After Taxes on Distributions	12.01%	2.96%	5.61%	Dec. 30, 2005
Class D Return After Taxes on Distributions and Sale of Fund Shares	Class D Shares	Return After Taxes on Distributions and Sale of Fund Shares	8.51%	2.77%	5.14%	Dec. 30, 2005
Morgan Stanley Capital International All Country World Index℠ (net of foreign withholding taxes) (reflects no deduction for expenses, fees, or taxes, except foreign withholding taxes)		Morgan Stanley Capital International All Country World IndexSM (net of foreign withholding taxes)	16.13%	(1.16%)	3.52%	Dec. 30, 2005
Global Moderate Allocation Index (reflects no deduction for expenses, fees, or taxes, except any applicable foreign withholding taxes)		Global Moderate Allocation Index	11.45%	1.89%	4.95%	Dec. 30, 2005
S&P 500® Index (reflects no deduction for expenses, fees, or taxes)		S&P 500® Index	16.00%	1.66%	4.12%	Dec. 30, 2005
Moderate Allocation Index (reflects no deduction for expenses, fees, or taxes, except any applicable foreign withholding taxes)		Moderate Allocation Index	11.74%	3.14%	5.21%	Dec. 30, 2005

Effective February 15, 2013, the Fund’s primary benchmark index changed from the S&P 500^® Index to the Morgan Stanley Capital International (“MSCI”) All Country World Index^SM to reflect the global investment strategies of the Fund. Additionally, the Fund changed the name of its secondary benchmark index from Moderate Allocation Index to Global Moderate Allocation Index and its composition from an internally-calculated, hypothetical combination of unmanaged indices that combines total returns from the Dow Jones Wilshire 5000 Index (40%), the Barclays U.S. Aggregate Bond Index (40%), the MSCI EAFE^® Index (18%), and the MSCI Emerging Markets Free Index^SM (2%) to an internally-calculated, hypothetical combination of unmanaged indices that combines total returns from the MSCI All Country World Index^SM (60%) and the Barclays Global Aggregate Bond Index (40%). The MSCI All Country World Index^SM is an unmanaged, free float-adjusted market capitalization weighted index that is designed to measure the equity market performance of global developed and emerging markets. Janus Capital believes that the foregoing benchmark index changes provide a more appropriate representation of the Fund’s revised investment strategy that includes an increased focus on global investments, including emerging markets.

After-tax returns are calculated using distributions for the Fund’s Class D Shares for the periods following February 16, 2010; and for the Fund’s Class J Shares, the predecessor share class, for the periods prior to February 16, 2010. If Class D Shares of the Fund had been available during these earlier periods, distributions may have been different and thus, after-tax returns may have been different from those shown. After-tax returns are calculated using the historically highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes. Actual after-tax returns depend on your individual tax situation and may differ from those shown in the preceding table. The after-tax return information shown above does not apply to Fund shares held through a tax-deferred account, such as a 401(k) plan or an IRA.

XML

Label	Element	Value
Risk/Return:	rr_RiskReturnAbstract
Registrant Name	dei_EntityRegistrantName	JANUS INVESTMENT FUND
Prospectus Date	rr_ProspectusDate	Oct. 28, 2013
INTECH U.S. Core Fund | Class A, C, S, I, T Shares
Risk/Return:	rr_RiskReturnAbstract
Risk/Return [Heading]	rr_RiskReturnHeading	FUND SUMMARY INTECH U.S. Core Fund
Objective [Heading]	rr_ObjectiveHeading	INVESTMENT OBJECTIVE
Objective, Primary [Text Block]	rr_ObjectivePrimaryTextBlock	INTECH U.S. Core Fund seeks long-term growth of capital.
Expense [Heading]	rr_ExpenseHeading	FEES AND EXPENSES OF THE FUND
Expense Narrative [Text Block]	rr_ExpenseNarrativeTextBlock	This table describes the fees and expenses that you may pay if you buy and hold Shares of the Fund. Each share class has different expenses, but represents an investment in the same Fund.
Shareholder Fees Caption [Text]	rr_ShareholderFeesCaption	SHAREHOLDER FEES (fees paid directly from your investment)
Operating Expenses Caption [Text]	rr_OperatingExpensesCaption	ANNUAL FUND OPERATING EXPENSES (expenses that you pay each year as a percentage of the value of your investment)
Portfolio Turnover [Heading]	rr_PortfolioTurnoverHeading	Portfolio Turnover:
Portfolio Turnover [Text Block]	rr_PortfolioTurnoverTextBlock	The Fund pays transaction costs, such as commissions, when it buys and sells securities (or “turns over” its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when Fund shares are held in a taxable account. These costs, which are not reflected in annual fund operating expenses or in the Example, affect the Fund’s performance. During the most recent fiscal year, the Fund’s portfolio turnover rate was 67% of the average value of its portfolio.
Portfolio Turnover, Rate	rr_PortfolioTurnoverRate	67.00%
Expense Breakpoint Discounts [Text]	rr_ExpenseBreakpointDiscounts	For Class A Shares, you may qualify for sales charge discounts if you and your family invest, or agree to invest in the future, at least $50,000 in the Fund or in other Janus mutual funds. More information about these and other discounts, as well as eligibility requirements for each share class, is available from your financial professional and in the “Purchases” section on page 51 of the Fund’s Prospectus and in the “Purchases” section on page 70 of the Fund’s Statement of Additional Information.
Expense Breakpoint, Minimum Investment Required [Amount]	rr_ExpenseBreakpointMinimumInvestmentRequiredAmount	$ 50,000
Expense Example [Heading]	rr_ExpenseExampleHeading	EXAMPLE:
Expense Example by Year [Heading]	rr_ExpenseExampleByYearHeading	The Example assumes that you invest $10,000 in the Fund for the time periods indicated and reinvest all dividends and distributions. The Example also assumes that your investment has a 5% return each year and that the Fund’s operating expenses remain the same. Although your actual costs may be higher or lower, based on these assumptions your costs would be:
Expense Example Narrative [Text Block]	rr_ExpenseExampleNarrativeTextBlock	The Example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds.
Expense Example by, Year, Caption [Text]	rr_ExpenseExampleByYearCaption	If Shares are redeemed:
Expense Example, No Redemption, By Year, Caption [Text]	rr_ExpenseExampleNoRedemptionByYearCaption	If Shares are not redeemed:
Strategy [Heading]	rr_StrategyHeading	PRINCIPAL INVESTMENT STRATEGIES
Strategy Narrative [Text Block]	rr_StrategyNarrativeTextBlock	The Fund invests, under normal circumstances, at least 80% of its net assets in U.S. common stocks from the universe of the S&P 500® Index, utilizing INTECH’s mathematical investment process. The S&P 500® Index is an unmanaged index of 500 stocks that is generally representative of the performance of larger companies in the United States. The Fund pursues its investment objective by applying a mathematical investment process to construct an investment portfolio from the universe of common stocks within its named benchmark index. The goal of this process is to build a portfolio of stocks in a more efficient combination than the named benchmark index. The process seeks to capitalize on the natural volatility of the market by searching for stocks within the index that have high relative volatility (providing the potential for excess returns) but that essentially move in opposite directions or have low correlation to each other (providing the potential for lower relative risk). By constructing the portfolio in this manner and periodically rebalancing the portfolio to maintain potentially more efficient weightings, INTECH’s mathematical investment process seeks to create a portfolio that, over time, produces returns in excess of its named benchmark index with risks similar to that of the benchmark index. The rebalancing techniques used by INTECH may result in a higher portfolio turnover compared to a “buy and hold” fund strategy. The Fund may lend portfolio securities on a short-term or long-term basis, in an amount equal to up to 1/3 of its total assets as determined at the time of the loan origination.
Risk [Heading]	rr_RiskHeading	PRINCIPAL INVESTMENT RISKS
Risk Narrative [Text Block]	rr_RiskNarrativeTextBlock	The biggest risk is that the Fund’s returns will vary, and you could lose money. The Fund is designed for long-term investors seeking an equity portfolio, including common stocks. Common stocks tend to be more volatile than many other investment choices. Market Risk. The value of the Fund’s portfolio may decrease if the value of an individual company or security, or multiple companies or securities, in the portfolio decreases. Further, regardless of how well individual companies or securities perform, the value of the Fund’s portfolio could also decrease if there are deteriorating economic or market conditions. It is important to understand that the value of your investment may fall, sometimes sharply, in response to changes in the market, and you could lose money. Investment Process Risk. The proprietary mathematical investment process used by INTECH may not achieve the desired results. There is a risk that INTECH’s method of identifying stocks with higher volatility than the named benchmark index or its method of identifying stocks that tend to move in the same or opposite direction relative to each other (correlation) will not result in selecting stocks with continuing volatility or the expected correlation. In INTECH’s history, which spans more than 25 years, INTECH’s mathematical investment process has experienced periods of both underperformance and outperformance relative to an identified benchmark. Even when the proprietary mathematical investment process is working appropriately, INTECH expects that there will be periods of underperformance relative to the benchmark. On an occasional basis, INTECH makes changes to its mathematical investment process. These changes may result in changes to the portfolio, might not provide the intended results, and may adversely impact the Fund’s performance. Portfolio Turnover Risk. Increased portfolio turnover may result in higher costs, which may have a negative effect on the Fund’s performance. In addition, higher portfolio turnover may result in the acceleration of capital gains and the recognition of greater levels of short-term capital gains, which are taxed at ordinary federal income tax rates when distributed to shareholders. Securities Lending Risk. The Fund may seek to earn additional income through lending its securities to certain qualified broker-dealers and institutions. There is the risk that when portfolio securities are lent, the securities may not be returned on a timely basis, and the Fund may experience delays and costs in recovering the security or gaining access to the collateral provided to the Fund to collateralize the loan. If the Fund is unable to recover a security on loan, the Fund may use the collateral to purchase replacement securities in the market. There is a risk that the value of the collateral could decrease below the cost of the replacement security by the time the replacement investment is made, resulting in a loss to the Fund. An investment in the Fund is not a bank deposit and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency.
Risk Lose Money [Text]	rr_RiskLoseMoney	The biggest risk is that the Fund’s returns will vary, and you could lose money.
Risk Not Insured Depository Institution [Text]	rr_RiskNotInsuredDepositoryInstitution	An investment in the Fund is not a bank deposit and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency.
Bar Chart and Performance Table [Heading]	rr_BarChartAndPerformanceTableHeading	PERFORMANCE INFORMATION
Performance Narrative [Text Block]	rr_PerformanceNarrativeTextBlock	The following information provides some indication of the risks of investing in the Fund by showing how the Fund’s performance has varied over time. Class T Shares (formerly named Class J Shares, the initial share class) of the Fund commenced operations with the Fund’s inception. Class A Shares, Class C Shares, Class S Shares, and Class I Shares of the Fund commenced operations on July 6, 2009. The performance shown for Class T Shares is calculated using the fees and expenses of Class T Shares in effect during the periods shown, net of any applicable fee and expense limitations or waivers. The performance shown for Class A Shares, Class C Shares, and Class S Shares for periods prior to July 6, 2009, reflects the performance of the Fund’s former Class J Shares, calculated using the fees and expenses of each respective share class, without the effect of any fee and expense limitations or waivers. The performance shown for Class I Shares for periods prior to July 6, 2009, reflects the performance of the Fund’s former Class J Shares, calculated using the fees and expenses of Class J Shares, net of any applicable fee and expense limitations or waivers. If Class A Shares, Class C Shares, Class S Shares, and Class I Shares of the Fund had been available during periods prior to July 6, 2009, the performance shown for each respective share class may have been different. The performance shown for periods following the Fund’s commencement of Class A Shares, Class C Shares, Class S Shares, and Class I Shares reflects the fees and expenses of each respective share class, net of any applicable fee and expense limitations or waivers. The bar chart depicts the change in performance from year to year during the periods indicated. The bar chart figures do not include any applicable sales charges that an investor may pay when they buy or sell Class A Shares or Class C Shares of the Fund. If sales charges were included, the returns would be lower. The table compares the Fund’s average annual returns for the periods indicated to a broad-based securities market index. The index is not actively managed and is not available for direct investment. All figures assume reinvestment of dividends and distributions. For certain periods, the Fund’s performance reflects the effect of expense waivers. Without the effect of these expense waivers, the performance shown would have been lower. The Fund’s past performance (before and after taxes) does not necessarily indicate how it will perform in the future. Updated performance information is available at janus.com/advisor/mutual-funds or by calling 1-877-335-2687.
Performance Information Illustrates Variability of Returns [Text]	rr_PerformanceInformationIllustratesVariabilityOfReturns	The following information provides some indication of the risks of investing in the Fund by showing how the Fund’s performance has varied over time. The bar chart depicts the change in performance from year to year during the periods indicated.
Performance Additional Market Index [Text]	rr_PerformanceAdditionalMarketIndex	The table compares the Fund’s average annual returns for the periods indicated to a broad-based securities market index. The index is not actively managed and is not available for direct investment. All figures assume reinvestment of dividends and distributions.
Performance Availability Phone [Text]	rr_PerformanceAvailabilityPhone	1-877-335-2687
Performance Availability Website Address [Text]	rr_PerformanceAvailabilityWebSiteAddress	janus.com/advisor/mutual-funds
Performance Past Does Not Indicate Future [Text]	rr_PerformancePastDoesNotIndicateFuture	The Fund’s past performance (before and after taxes) does not necessarily indicate how it will perform in the future.
Bar Chart [Heading]	rr_BarChartHeading	Annual Total Returns for Class T Shares (calendar year-end)
Bar Chart Does Not Reflect Sales Loads [Text]	rr_BarChartDoesNotReflectSalesLoads	The bar chart figures do not include any applicable sales charges that an investor may pay when they buy or sell Class A Shares or Class C Shares of the Fund. If sales charges were included, the returns would be lower.
Bar Chart Closing [Text Block]	rr_BarChartClosingTextBlock	Best Quarter:  Second Quarter 2009  14.79%          Worst Quarter:  Fourth Quarter 2008  −21.49%
Year to Date Return, Label	rr_YearToDateReturnLabel	The Fund’s year-to-date return as of the calendar quarter ended September 30, 2013 was 21.68%.
Performance Table Heading	rr_PerformanceTableHeading	Average Annual Total Returns (periods ended 12/31/12)
Performance Table Uses Highest Federal Rate	rr_PerformanceTableUsesHighestFederalRate	After-tax returns are calculated using the historically highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes.
Performance Table Not Relevant to Tax Deferred	rr_PerformanceTableNotRelevantToTaxDeferred	Actual after-tax returns depend on your individual tax situation and may differ from those shown in the preceding table. The after-tax return information shown above does not apply to Fund shares held through a tax-deferred account, such as a 401(k) plan or an IRA.
Performance Table One Class of after Tax Shown [Text]	rr_PerformanceTableOneClassOfAfterTaxShown	After-tax returns are only shown for Class T Shares of the Fund. After-tax returns for the other classes of Shares will vary from those shown for Class T Shares due to varying sales charges (as applicable), fees, and expenses among the classes.
Performance Table Narrative	rr_PerformanceTableNarrativeTextBlock	The Standard & Poor’s (“S&P”) 500® Index is a commonly recognized, market-capitalization weighted index of 500 widely held equity securities, designed to measure broad U.S. equity performance. This index is used to calculate the performance fee adjustment. After-tax returns are calculated using distributions for the Fund’s Class T Shares (formerly named Class J Shares, the initial share class). After-tax returns are calculated using the historically highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes. Actual after-tax returns depend on your individual tax situation and may differ from those shown in the preceding table. The after-tax return information shown above does not apply to Fund shares held through a tax-deferred account, such as a 401(k) plan or an IRA. After-tax returns are only shown for Class T Shares of the Fund. After-tax returns for the other classes of Shares will vary from those shown for Class T Shares due to varying sales charges (as applicable), fees, and expenses among the classes.
Performance Table Closing [Text Block]	rr_PerformanceTableClosingTextBlock	Updated performance information is available at janus.com/advisor/mutual-funds or by calling 1-877-335-2687.
INTECH U.S. Core Fund | Class A, C, S, I, T Shares | Class A
Risk/Return:	rr_RiskReturnAbstract
Shareholder Fees Column [Text]	rr_ShareholderFeesColumnName	Class A
Maximum Sales Charge (load) Imposed on Purchases (as a percentage of offering price)	rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice	5.75%
Maximum Deferred Sales Charge (load) (as a percentage of the lower of original purchase price or redemption proceeds)	rr_MaximumDeferredSalesChargeOverOther	none
Operating Expenses Column [Text]	rr_OperatingExpensesColumnName	Class A
Management Fees (may adjust up or down)	rr_ManagementFeesOverAssets	0.60%
Distribution/Service (12b-1) Fees	rr_DistributionAndService12b1FeesOverAssets	0.25%
Other Expenses	rr_OtherExpensesOverAssets	0.13%
Total Annual Fund Operating Expenses	rr_ExpensesOverAssets	0.98%
Expense Example, By Year, Column [Text]	rr_ExpenseExampleByYearColumnName	Class A Shares
1 Year	rr_ExpenseExampleYear01	669
3 Years	rr_ExpenseExampleYear03	869
5 Years	rr_ExpenseExampleYear05	1,086
10 Years	rr_ExpenseExampleYear10	1,707
Expense Example, No Redemption, By Year, Column [Text]	rr_ExpenseExampleNoRedemptionByYearColumnName	Class A Shares
1 Year	rr_ExpenseExampleNoRedemptionYear01	669
3 Years	rr_ExpenseExampleNoRedemptionYear03	869
5 Years	rr_ExpenseExampleNoRedemptionYear05	1,086
10 Years	rr_ExpenseExampleNoRedemptionYear10	1,707
INTECH U.S. Core Fund | Class A, C, S, I, T Shares | Class C
Risk/Return:	rr_RiskReturnAbstract
Shareholder Fees Column [Text]	rr_ShareholderFeesColumnName	Class C
Maximum Sales Charge (load) Imposed on Purchases (as a percentage of offering price)	rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice	none
Maximum Deferred Sales Charge (load) (as a percentage of the lower of original purchase price or redemption proceeds)	rr_MaximumDeferredSalesChargeOverOther	1.00%
Operating Expenses Column [Text]	rr_OperatingExpensesColumnName	Class C
Management Fees (may adjust up or down)	rr_ManagementFeesOverAssets	0.60%
Distribution/Service (12b-1) Fees	rr_DistributionAndService12b1FeesOverAssets	1.00%
Other Expenses	rr_OtherExpensesOverAssets	0.17%
Total Annual Fund Operating Expenses	rr_ExpensesOverAssets	1.77%
Expense Example, By Year, Column [Text]	rr_ExpenseExampleByYearColumnName	Class C Shares
1 Year	rr_ExpenseExampleYear01	280
3 Years	rr_ExpenseExampleYear03	557
5 Years	rr_ExpenseExampleYear05	959
10 Years	rr_ExpenseExampleYear10	2,084
Expense Example, No Redemption, By Year, Column [Text]	rr_ExpenseExampleNoRedemptionByYearColumnName	Class C Shares
1 Year	rr_ExpenseExampleNoRedemptionYear01	180
3 Years	rr_ExpenseExampleNoRedemptionYear03	557
5 Years	rr_ExpenseExampleNoRedemptionYear05	959
10 Years	rr_ExpenseExampleNoRedemptionYear10	2,084
INTECH U.S. Core Fund | Class A, C, S, I, T Shares | Class S
Risk/Return:	rr_RiskReturnAbstract
Shareholder Fees Column [Text]	rr_ShareholderFeesColumnName	Class S
Maximum Sales Charge (load) Imposed on Purchases (as a percentage of offering price)	rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice	none
Maximum Deferred Sales Charge (load) (as a percentage of the lower of original purchase price or redemption proceeds)	rr_MaximumDeferredSalesChargeOverOther	none
Operating Expenses Column [Text]	rr_OperatingExpensesColumnName	Class S
Management Fees (may adjust up or down)	rr_ManagementFeesOverAssets	0.60%
Distribution/Service (12b-1) Fees	rr_DistributionAndService12b1FeesOverAssets	0.25%
Other Expenses	rr_OtherExpensesOverAssets	0.32%
Total Annual Fund Operating Expenses	rr_ExpensesOverAssets	1.17%
Expense Example, By Year, Column [Text]	rr_ExpenseExampleByYearColumnName	Class S Shares
1 Year	rr_ExpenseExampleYear01	119
3 Years	rr_ExpenseExampleYear03	372
5 Years	rr_ExpenseExampleYear05	644
10 Years	rr_ExpenseExampleYear10	1,420
Expense Example, No Redemption, By Year, Column [Text]	rr_ExpenseExampleNoRedemptionByYearColumnName	Class S Shares
1 Year	rr_ExpenseExampleNoRedemptionYear01	119
3 Years	rr_ExpenseExampleNoRedemptionYear03	372
5 Years	rr_ExpenseExampleNoRedemptionYear05	644
10 Years	rr_ExpenseExampleNoRedemptionYear10	1,420
INTECH U.S. Core Fund | Class A, C, S, I, T Shares | Class I
Risk/Return:	rr_RiskReturnAbstract
Shareholder Fees Column [Text]	rr_ShareholderFeesColumnName	Class I
Maximum Sales Charge (load) Imposed on Purchases (as a percentage of offering price)	rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice	none
Maximum Deferred Sales Charge (load) (as a percentage of the lower of original purchase price or redemption proceeds)	rr_MaximumDeferredSalesChargeOverOther	none
Operating Expenses Column [Text]	rr_OperatingExpensesColumnName	Class I
Management Fees (may adjust up or down)	rr_ManagementFeesOverAssets	0.60%
Distribution/Service (12b-1) Fees	rr_DistributionAndService12b1FeesOverAssets	none
Other Expenses	rr_OtherExpensesOverAssets	0.15%
Total Annual Fund Operating Expenses	rr_ExpensesOverAssets	0.75%
Expense Example, By Year, Column [Text]	rr_ExpenseExampleByYearColumnName	Class I Shares
1 Year	rr_ExpenseExampleYear01	77
3 Years	rr_ExpenseExampleYear03	240
5 Years	rr_ExpenseExampleYear05	417
10 Years	rr_ExpenseExampleYear10	930
Expense Example, No Redemption, By Year, Column [Text]	rr_ExpenseExampleNoRedemptionByYearColumnName	Class I Shares
1 Year	rr_ExpenseExampleNoRedemptionYear01	77
3 Years	rr_ExpenseExampleNoRedemptionYear03	240
5 Years	rr_ExpenseExampleNoRedemptionYear05	417
10 Years	rr_ExpenseExampleNoRedemptionYear10	930
INTECH U.S. Core Fund | Class A, C, S, I, T Shares | Class T
Risk/Return:	rr_RiskReturnAbstract
Shareholder Fees Column [Text]	rr_ShareholderFeesColumnName	Class T
Maximum Sales Charge (load) Imposed on Purchases (as a percentage of offering price)	rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice	none
Maximum Deferred Sales Charge (load) (as a percentage of the lower of original purchase price or redemption proceeds)	rr_MaximumDeferredSalesChargeOverOther	none
Operating Expenses Column [Text]	rr_OperatingExpensesColumnName	Class T
Management Fees (may adjust up or down)	rr_ManagementFeesOverAssets	0.60%
Distribution/Service (12b-1) Fees	rr_DistributionAndService12b1FeesOverAssets	none
Other Expenses	rr_OtherExpensesOverAssets	0.32%
Total Annual Fund Operating Expenses	rr_ExpensesOverAssets	0.92%
Expense Example, By Year, Column [Text]	rr_ExpenseExampleByYearColumnName	Class T Shares
1 Year	rr_ExpenseExampleYear01	94
3 Years	rr_ExpenseExampleYear03	293
5 Years	rr_ExpenseExampleYear05	509
10 Years	rr_ExpenseExampleYear10	1,131
Expense Example, No Redemption, By Year, Column [Text]	rr_ExpenseExampleNoRedemptionByYearColumnName	Class T Shares
1 Year	rr_ExpenseExampleNoRedemptionYear01	94
3 Years	rr_ExpenseExampleNoRedemptionYear03	293
5 Years	rr_ExpenseExampleNoRedemptionYear05	509
10 Years	rr_ExpenseExampleNoRedemptionYear10	$ 1,131
2004	rr_AnnualReturn2004	17.68%
2005	rr_AnnualReturn2005	11.06%
2006	rr_AnnualReturn2006	11.37%
2007	rr_AnnualReturn2007	6.40%
2008	rr_AnnualReturn2008	(36.57%)
2009	rr_AnnualReturn2009	22.91%
2010	rr_AnnualReturn2010	16.28%
2011	rr_AnnualReturn2011	4.97%
2012	rr_AnnualReturn2012	14.62%
Bar Chart, Year to Date Return, Date	rr_BarChartYearToDateReturnDate	Sep. 30, 2013
Bar Chart, Year to Date Return	rr_BarChartYearToDateReturn	21.68%
Highest Quarterly Return, Label	rr_HighestQuarterlyReturnLabel	Best Quarter:
Highest Quarterly Return, Date	rr_BarChartHighestQuarterlyReturnDate	Jun. 30, 2009
Highest Quarterly Return	rr_BarChartHighestQuarterlyReturn	14.79%
Lowest Quarterly Return, Label	rr_LowestQuarterlyReturnLabel	Worst Quarter:
Lowest Quarterly Return, Date	rr_BarChartLowestQuarterlyReturnDate	Dec. 31, 2008
Lowest Quarterly Return	rr_BarChartLowestQuarterlyReturn	(21.49%)
INTECH U.S. Core Fund | Class A, C, S, I, T Shares | Return Before Taxes | Class A
Risk/Return:	rr_RiskReturnAbstract
Column	rr_AverageAnnualReturnColumnName	Class A Shares
Label	rr_AverageAnnualReturnLabel	Return Before Taxes	[1]
1 Year	rr_AverageAnnualReturnYear01	7.97%
5 Years	rr_AverageAnnualReturnYear05	0.36%
Since Inception	rr_AverageAnnualReturnSinceInception	7.55%
Inception Date	rr_AverageAnnualReturnInceptionDate	Feb. 28, 2003
INTECH U.S. Core Fund | Class A, C, S, I, T Shares | Return Before Taxes | Class C
Risk/Return:	rr_RiskReturnAbstract
Column	rr_AverageAnnualReturnColumnName	Class C Shares
Label	rr_AverageAnnualReturnLabel	Return Before Taxes	[2]
1 Year	rr_AverageAnnualReturnYear01	12.46%
5 Years	rr_AverageAnnualReturnYear05	0.79%
Since Inception	rr_AverageAnnualReturnSinceInception	7.39%
Inception Date	rr_AverageAnnualReturnInceptionDate	Feb. 28, 2003
INTECH U.S. Core Fund | Class A, C, S, I, T Shares | Return Before Taxes | Class S
Risk/Return:	rr_RiskReturnAbstract
Column	rr_AverageAnnualReturnColumnName	Class S Shares
Label	rr_AverageAnnualReturnLabel	Return Before Taxes
1 Year	rr_AverageAnnualReturnYear01	14.33%
5 Years	rr_AverageAnnualReturnYear05	1.40%
Since Inception	rr_AverageAnnualReturnSinceInception	8.01%
Inception Date	rr_AverageAnnualReturnInceptionDate	Feb. 28, 2003
INTECH U.S. Core Fund | Class A, C, S, I, T Shares | Return Before Taxes | Class I
Risk/Return:	rr_RiskReturnAbstract
Column	rr_AverageAnnualReturnColumnName	Class I Shares
Label	rr_AverageAnnualReturnLabel	Return Before Taxes
1 Year	rr_AverageAnnualReturnYear01	14.80%
5 Years	rr_AverageAnnualReturnYear05	1.75%
Since Inception	rr_AverageAnnualReturnSinceInception	8.47%
Inception Date	rr_AverageAnnualReturnInceptionDate	Feb. 28, 2003
INTECH U.S. Core Fund | Class A, C, S, I, T Shares | Return Before Taxes | Class T
Risk/Return:	rr_RiskReturnAbstract
Column	rr_AverageAnnualReturnColumnName	Class T Shares
Label	rr_AverageAnnualReturnLabel	Return Before Taxes
1 Year	rr_AverageAnnualReturnYear01	14.62%
5 Years	rr_AverageAnnualReturnYear05	1.75%
Since Inception	rr_AverageAnnualReturnSinceInception	8.47%
Inception Date	rr_AverageAnnualReturnInceptionDate	Feb. 28, 2003
INTECH U.S. Core Fund | Class A, C, S, I, T Shares | Return After Taxes on Distributions | Class T
Risk/Return:	rr_RiskReturnAbstract
Column	rr_AverageAnnualReturnColumnName	Class T Shares
Label	rr_AverageAnnualReturnLabel	Return After Taxes on Distributions
1 Year	rr_AverageAnnualReturnYear01	14.38%
5 Years	rr_AverageAnnualReturnYear05	1.54%
Since Inception	rr_AverageAnnualReturnSinceInception	7.79%
Inception Date	rr_AverageAnnualReturnInceptionDate	Feb. 28, 2003
INTECH U.S. Core Fund | Class A, C, S, I, T Shares | Return After Taxes on Distributions and Sale of Fund Shares | Class T
Risk/Return:	rr_RiskReturnAbstract
Column	rr_AverageAnnualReturnColumnName	Class T Shares
Label	rr_AverageAnnualReturnLabel	Return After Taxes on Distributions and Sale of Fund Shares
1 Year	rr_AverageAnnualReturnYear01	9.83%
5 Years	rr_AverageAnnualReturnYear05	1.45%
Since Inception	rr_AverageAnnualReturnSinceInception	7.32%
Inception Date	rr_AverageAnnualReturnInceptionDate	Feb. 28, 2003
INTECH U.S. Core Fund | Class A, C, S, I, T Shares | S&P 500® Index (reflects no deduction for expenses, fees, or taxes)
Risk/Return:	rr_RiskReturnAbstract
Label	rr_AverageAnnualReturnLabel	S&P 500® Index
1 Year	rr_AverageAnnualReturnYear01	16.00%
5 Years	rr_AverageAnnualReturnYear05	1.66%
Since Inception	rr_AverageAnnualReturnSinceInception	7.68%
Inception Date	rr_AverageAnnualReturnInceptionDate	Feb. 28, 2003

[1] Calculated assuming maximum permitted sales loads.

[2] The one year return is calculated to include the contingent deferred sales charge.

XML

Label	Element	Value
Risk/Return:	rr_RiskReturnAbstract
Registrant Name	dei_EntityRegistrantName	JANUS INVESTMENT FUND
Prospectus Date	rr_ProspectusDate	Oct. 28, 2013
Janus Global Allocation Fund - Moderate | Class D Shares
Risk/Return:	rr_RiskReturnAbstract
Risk/Return [Heading]	rr_RiskReturnHeading	FUND SUMMARY Janus Global Allocation Fund – Moderate (formerly named Janus Moderate Allocation Fund)
Objective [Heading]	rr_ObjectiveHeading	INVESTMENT OBJECTIVE
Objective, Primary [Text Block]	rr_ObjectivePrimaryTextBlock	Janus Global Allocation Fund – Moderate seeks total return through growth of capital and income.
Expense [Heading]	rr_ExpenseHeading	FEES AND EXPENSES OF THE FUND
Expense Narrative [Text Block]	rr_ExpenseNarrativeTextBlock	This table describes the fees and expenses that you may pay if you buy and hold Shares of the Fund.
Operating Expenses Caption [Text]	rr_OperatingExpensesCaption	ANNUAL FUND OPERATING EXPENSES (expenses that you pay each year as a percentage of the value of your investment)
Portfolio Turnover [Heading]	rr_PortfolioTurnoverHeading	Portfolio Turnover:
Portfolio Turnover [Text Block]	rr_PortfolioTurnoverTextBlock	The Fund pays transaction costs, such as commissions, when it buys and sells securities (or “turns over” its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when Fund shares are held in a taxable account. These costs, which are not reflected in annual fund operating expenses or in the Example, affect the Fund’s performance. During the most recent fiscal year, the Fund’s portfolio turnover rate was 64% of the average value of its portfolio.
Portfolio Turnover, Rate	rr_PortfolioTurnoverRate	64.00%
Expense Example [Heading]	rr_ExpenseExampleHeading	EXAMPLE:
Expense Example by Year [Heading]	rr_ExpenseExampleByYearHeading	The Example assumes that you invest $10,000 in the Fund for the time periods indicated, reinvest all dividends and distributions, and then redeem all of your Shares at the end of each period. The Example also assumes that your investment has a 5% return each year and that the Fund’s operating expenses (including the operating expenses of the underlying funds) remain the same. Although your actual costs may be higher or lower, based on these assumptions your costs would be:
Expense Example Narrative [Text Block]	rr_ExpenseExampleNarrativeTextBlock	The Example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds.
Strategy [Heading]	rr_StrategyHeading	PRINCIPAL INVESTMENT STRATEGIES
Strategy Narrative [Text Block]	rr_StrategyNarrativeTextBlock	The Fund seeks to achieve its investment objective by investing in other Janus mutual funds (“underlying funds”) that represent a variety of asset classes and investment styles and provide exposure to issuers that are economically tied to countries throughout the world. Through its investments in underlying funds, the Fund invests in issuers from several different countries and may, under unusual circumstances, be invested in a single country. As a result, the Fund normally will have approximately 40% of its net assets allocated to non-U.S. investments. The Fund may also have significant exposure to emerging markets. The Fund pursues this objective by investing in a diversified portfolio of underlying funds, resulting in an allocation of the Fund’s investments that normally provides exposure of approximately 55% to equity investments, 35% to fixed-income securities and money market instruments, and 10% to alternative investments. The target allocation and the allocation of the Fund’s assets among underlying funds are based on quantitative and qualitative analysis. Because it invests in other funds, the Fund is considered a “fund of funds.” The Fund’s asset allocation is intended to diversify investments throughout the world among equity investments, fixed-income securities, cash equivalents, and alternative investments. The portfolio manager determines the overall composition of the Fund, oversees the investment process, and is responsible for the day-to-day management of the Fund. The portfolio manager continually monitors asset class allocations and periodically rebalances the Fund’s investments in the underlying funds. The portfolio manager also regularly reviews the allocation of Fund assets in the underlying funds and may modify the underlying funds’ weightings or substitute other underlying funds to emphasize and mitigate risk exposures that may arise as a result of the implementation of the allocations. An independent asset allocation service provides evaluations of asset allocations that the portfolio manager may use in implementing the allocations among the underlying funds. Additionally, the portfolio manager consults with a committee (the “Janus Global Allocation Committee”) to regularly review the broad market, macroeconomic conditions and other global financial factors that may impact the Fund’s allocation of assets among the underlying funds and asset classes. The Janus Global Allocation Committee is comprised of investment professionals of Janus Capital and may also include investment professionals of Janus Capital’s affiliated investment advisers. The portfolio manager and Janus Global Allocation Committee normally meet on a quarterly basis. The portfolio manager may change the Fund’s asset class allocations, the underlying funds, an underlying fund’s asset category, or weightings among asset classes or underlying funds without prior shareholder notice. The Fund will normally allocate approximately 55% of its investments to underlying funds that provide varying exposure to common stocks of large U.S.-based companies, small- to mid-capitalization companies, and international companies (including those with exposure to emerging markets), approximately 35% of its investments to underlying bond funds and money market instruments, and approximately 10% of its investments to underlying funds that seek returns uncorrelated with the returns of stocks and bonds by providing exposure to alternative investments and alternative investment strategies. Refer to Appendix A in this Prospectus for a brief description of the investment strategies of each of the currently available underlying funds. When market conditions dictate a more defensive strategy, the Fund or an underlying fund may temporarily hold cash or invest its assets in temporary investments. In that case, the Fund may take positions that are inconsistent with its investment objective. As a result, the Fund may not achieve its investment objective.
Risk [Heading]	rr_RiskHeading	PRINCIPAL INVESTMENT RISKS
Risk Narrative [Text Block]	rr_RiskNarrativeTextBlock	The biggest risk is that the Fund’s returns will vary, and you could lose money. The Fund is designed for long-term investors seeking growth of capital and income. Investments in a portfolio with common stock and alternative investment exposure tend to be more volatile than many other investment choices. Main Risks Associated with the Fund Allocation Risk. The Fund’s ability to achieve its investment objective depends largely upon the portfolio manager’s allocation of assets among the underlying funds and other securities, using the optimization process (a process that utilizes quantitative analysis of a number of factors, such as historical risk, performance, fund classifications, and the relationship among underlying funds) and the judgment of the portfolio manager. You could lose money on your investment in the Fund as a result of these allocations. The Fund will typically invest in a number of different underlying funds; however, to the extent that the Fund invests a significant portion of its assets in a single underlying fund, it will be more sensitive to the risks associated with that fund and any investments in which that fund focuses. Affiliated Fund Risk. Janus Capital has the authority to select and substitute underlying affiliated mutual funds. The fees paid to Janus Capital by some Janus mutual funds are generally higher than the fees paid to Janus Capital by the Fund or by other funds and share classes available for investment by the Fund. These conditions may create a conflict of interest when selecting underlying affiliated mutual funds and share classes for investment. Janus Capital, however, is a fiduciary to the Fund and its shareholders and is legally obligated to act in their best interest when selecting underlying affiliated mutual funds. Main Risks Associated with the Underlying Funds and Securities The biggest risk is that the underlying funds’ returns will vary, and you could lose money. Market Risk. Approximately 55% of the Fund’s assets are allocated to equity investments through investments in underlying funds. The value of an underlying fund’s portfolio may decrease if the value of an individual company or security, or multiple companies or securities, in the portfolio decreases or if a portfolio manager’s belief about a company’s intrinsic worth is incorrect. Further, regardless of how well individual companies or securities perform, the value of an underlying fund’s portfolio could also decrease if there are deteriorating economic or market conditions. It is important to understand that the value of your investment may fall, sometimes sharply, in response to changes in the market, and you could lose money. Fixed-Income Securities Risk. Approximately 35% of the Fund’s assets are allocated to fixed-income securities through investments in underlying funds. Typically, the values of fixed-income securities change inversely with prevailing interest rates. Therefore, a fundamental risk of fixed-income securities is interest rate risk, which is the risk that the value of such securities will generally decline as prevailing interest rates rise, which may cause an underlying fund’s net asset value to likewise decrease. How specific fixed-income securities may react to changes in interest rates will depend on the specific characteristics of each security. Fixed-income securities are also subject to credit risk, prepayment risk, valuation risk, and liquidity risk. Credit risk is the risk that the credit strength of an issuer of a fixed-income security will weaken and/or that the issuer will be unable to make timely principal and interest payments and that the security may go into default. Prepayment risk is the risk that during periods of falling interest rates, certain fixed-income securities with higher interest rates, such as mortgage- and asset-backed securities, may be prepaid by their issuers thereby reducing the amount of interest payments. Valuation risk is the risk that one or more of the fixed-income securities in which an underlying fund invests are priced differently than the value realized upon such security’s sale. In times of market instability, valuation may be more difficult. Liquidity risk is the risk that fixed-income securities may be difficult or impossible to sell at the time that an underlying fund’s portfolio manager would like or at the price the portfolio manager believes the security is currently worth. Foreign Exposure Risk. Certain underlying funds may have significant exposure to foreign markets as a result of their investments in foreign securities, including investments in emerging markets, which can be more volatile than the U.S. markets. As a result, an underlying fund’s returns and net asset value may be affected to a large degree by fluctuations in currency exchange rates or political or economic conditions in a particular country. A market swing in one or more countries or regions where an underlying fund has invested a significant amount of its assets may have a greater effect on an underlying fund’s performance than it would in a more geographically diversified portfolio. An underlying fund’s investments in emerging market countries may involve risks greater than, or in addition to, the risks of investing in more developed countries. Emerging Markets Risk. The risks of foreign investing mentioned above are heightened when investing in emerging markets. Emerging markets securities involve a number of additional risks, which may result from less government supervision and regulation of business and industry practices (including the potential lack of strict finance and accounting controls and standards), stock exchanges, brokers, and listed companies, making these investments potentially more volatile in price and less liquid than investments in developed securities markets, resulting in greater risk to investors. In addition, an underlying fund’s investments may be denominated in foreign currencies and therefore, changes in the value of a country’s currency compared to the U.S. dollar may affect the value of an underlying fund’s investments. To the extent that an underlying fund invests a significant portion of its assets in the securities of issuers in or companies of a single country or region, it is more likely to be impacted by events or conditions affecting that country or region, which could have a negative impact on the Fund’s performance. Some of the risks of investing directly in foreign and emerging market securities may be reduced when an underlying fund invests indirectly in foreign securities through various other investment vehicles including derivatives, which also involve other risks. Sovereign Debt Risk. An underlying fund may invest in U.S. and foreign government debt securities (“sovereign debt”). Investments in U.S. sovereign debt are considered low risk. However, investments in non-U.S. sovereign debt can involve a high degree of risk, including the risk that the governmental entity that controls the repayment of sovereign debt may not be willing or able to repay the principal and/or to pay the interest on its sovereign debt in a timely manner. A sovereign debtor’s willingness or ability to satisfy its debt obligation may be affected by various factors including, but not limited to, its cash flow situation, the extent of its foreign currency reserves, the availability of foreign exchange when a payment is due, and the relative size of its debt position in relation to its economy as a whole. In the event of default, there may be limited or no legal remedies for collecting sovereign debt and there may be no bankruptcy proceedings through which the underlying fund may collect all or part of the sovereign debt that a governmental entity has not repaid. Mortgage-Backed Securities Risk. Mortgage-backed securities are classified generally as either commercial mortgage-backed securities or residential mortgage-backed securities, each of which is subject to certain specific risks. Mortgage-backed securities tend to be more sensitive to changes in interest rates than other types of debt securities. Investments in mortgage-backed securities are subject to both extension risk, where borrowers extend the duration of their mortgages in times of rising interest rates, and prepayment risk, where borrowers pay off their mortgages sooner than expected in times of declining interest rates. These risks may reduce the Fund’s returns. In addition, investments in mortgage-backed securities, including those comprised of subprime mortgages, may be subject to a higher degree of credit risk, valuation risk, and liquidity risk than various other types of fixed-income securities. Alternative Investments Allocation Risk. Approximately 10% of the Fund’s assets are allocated to alternative investments through investments in underlying funds that invest in alternative investment strategies. In connection with the Fund’s allocation to alternative investments, the Fund may invest in a Janus underlying fund, Janus Diversified Alternatives Fund, which seeks returns uncorrelated with the returns generated by investments in stocks and bonds. In addition, as part of its alternative investments allocation, the Fund may invest in Janus Global Real Estate Fund. Janus Diversified Alternatives Fund’s ability to achieve its investment objective depends largely upon the successful evaluation of the risk, potential returns, and correlation properties with respect to its investments. There is a risk that the returns provided by alternative investments may be subject to high volatility and that an underlying fund’s portfolio manager’s beliefs about the expected returns, risk and correlation properties of one or more of an underlying fund’s investments may be incorrect. There is also a risk that an underlying fund’s investments will correlate with the performance of stocks and bonds to a greater degree than anticipated. Janus Capital does not have prior experience managing the investment strategy of Janus Diversified Alternatives Fund, and there is no guarantee that the investment techniques and analysis used by the underlying fund’s portfolio managers will produce the desired results. All of these factors may negatively affect your investment in the Fund and you could lose money. Investment in the underlying funds also involves derivatives, counterparty, leverage, real estate-related, and commodity-linked investment risks. Counterparty Risk. Certain derivative and “over-the-counter” instruments, such as swaps and forwards, are subject to the risk that the other party to a contract will not fulfill its contractual obligations. Commodity-Linked Investments Risk. Certain underlying funds may invest in derivatives that have exposure to the commodities markets. Such exposure may subject an underlying fund to greater volatility than investments in traditional securities. The value of a commodity-linked derivative investment typically is based upon the price movements of a physical commodity (such as heating oil, livestock, or agricultural products), a commodity futures contract or commodity index, or some other readily measurable economic variable. The value of commodity-linked derivative instruments may therefore be affected by changes in overall market movements, volatility of the underlying benchmark, changes in interest rates, or other factors affecting a particular industry or commodity such as drought, floods, weather, livestock disease, embargoes, tariffs, and international economic, political, and regulatory developments. Derivatives Risk. Certain underlying funds may invest in derivatives. Derivatives can be highly volatile and involve risks in addition to the risks of the underlying referenced securities. Gains or losses from a derivative investment can be substantially greater than the derivative’s original cost, and can therefore involve leverage. Leverage may cause an underlying fund to be more volatile than if it had not used leverage. Derivatives can be less liquid than other types of investments and entail the risk that the counterparty will default on its payment obligations. Exchange-Traded Funds Risk. Certain underlying funds may purchase shares of exchange-traded funds (“ETFs”) to gain exposure to a particular portion of the market. ETFs are pooled investment vehicles, which may be managed or unmanaged, that generally seek to track the performance of a specific index. ETFs are traded on an exchange at market prices that may vary from the net asset value of their underlying investments. When an underlying fund invests in an ETF, in addition to directly bearing the expenses associated with its own operations, it will bear a pro rata portion of the ETF’s expenses. ETFs have certain inherent risks generally associated with investments in a portfolio of securities in which the ETF is invested, including the risk that the general level of stock prices may decline, thereby adversely affecting the value of each unit of the ETF. ETFs also involve the risk that an active trading market for an ETF’s shares may not develop or be maintained. Exchange-Traded Notes Risk. Certain underlying funds may invest in exchange-traded notes (“ETNs”), which are debt securities whose returns are linked to a particular index. ETNs are typically linked to the performance of a commodities index that reflects the potential return on unleveraged investments in futures contracts of physical commodities, plus a specified rate of interest that could be earned on cash collateral. ETNs are subject to credit risk and counterparty risk. The value of an ETN may vary and may be influenced by time to maturity, level of supply and demand for the ETN, volatility and lack of liquidity in underlying commodities markets, changes in the applicable interest rates, changes in the issuer’s credit rating, and economic, legal, political, or geographic events that affect the referenced commodity. When an underlying fund invests in ETNs it will bear its proportionate share of any fees and expenses borne by the ETN. There may be restrictions on an underlying fund’s right to redeem its investment in an ETN, which is meant to be held until maturity. An underlying fund’s decision to sell its ETN holdings may be limited by the availability of a secondary market. An investment in the Fund is not a bank deposit and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency.
Risk Lose Money [Text]	rr_RiskLoseMoney	The biggest risk is that the Fund’s returns will vary, and you could lose money.
Risk Not Insured Depository Institution [Text]	rr_RiskNotInsuredDepositoryInstitution	An investment in the Fund is not a bank deposit and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency.
Bar Chart and Performance Table [Heading]	rr_BarChartAndPerformanceTableHeading	PERFORMANCE INFORMATION
Performance Narrative [Text Block]	rr_PerformanceNarrativeTextBlock	The following information provides some indication of the risks of investing in the Fund by showing how the Fund’s performance has varied over time. Class D Shares of the Fund commenced operations on February 16, 2010, as a result of the restructuring of Class J Shares, the predecessor share class. The performance shown for Class D Shares for periods prior to February 16, 2010, reflects the performance of the Fund’s former Class J Shares, calculated using the fees and expenses in effect during the periods shown, net of any applicable fee and expense limitations or waivers. If Class D Shares of the Fund had been available during periods prior to February 16, 2010, the performance shown may have been different. The performance shown for periods following the Fund’s commencement of Class D Shares reflects the fees and expenses of Class D Shares, net of any applicable fee and expense limitations or waivers. The bar chart depicts the change in performance from year to year during the periods indicated. Performance information for each underlying fund is available in its prospectus and/or the most recent annual or semiannual report. The table compares the Fund’s average annual returns for the periods indicated to broad-based securities market indices. The indices are not actively managed and are not available for direct investment. All figures assume reinvestment of dividends and distributions. For certain periods, the Fund’s performance reflects the effect of expense waivers. Without the effect of these expense waivers, the performance shown would have been lower. The Fund’s past performance (before and after taxes) does not necessarily indicate how it will perform in the future. Updated performance information is available at janus.com/allfunds or by calling 1-800-525-3713.
Performance Information Illustrates Variability of Returns [Text]	rr_PerformanceInformationIllustratesVariabilityOfReturns	The following information provides some indication of the risks of investing in the Fund by showing how the Fund’s performance has varied over time. The bar chart depicts the change in performance from year to year during the periods indicated.
Performance Additional Market Index [Text]	rr_PerformanceAdditionalMarketIndex	The table compares the Fund’s average annual returns for the periods indicated to broad-based securities market indices. The indices are not actively managed and are not available for direct investment. All figures assume reinvestment of dividends and distributions.
Performance Availability Phone [Text]	rr_PerformanceAvailabilityPhone	1-800-525-3713
Performance Availability Website Address [Text]	rr_PerformanceAvailabilityWebSiteAddress	janus.com/allfunds
Performance Past Does Not Indicate Future [Text]	rr_PerformancePastDoesNotIndicateFuture	The Fund’s past performance (before and after taxes) does not necessarily indicate how it will perform in the future.
Bar Chart [Heading]	rr_BarChartHeading	Annual Total Returns for Class D Shares (calendar year-end)
Bar Chart Closing [Text Block]	rr_BarChartClosingTextBlock	Best Quarter:  Second Quarter 2009  14.27%          Worst Quarter:  Fourth Quarter 2008  −11.62%
Year to Date Return, Label	rr_YearToDateReturnLabel	The Fund’s year-to-date return as of the calendar quarter ended September 30, 2013 was 9.53%.
Performance Table Heading	rr_PerformanceTableHeading	Average Annual Total Returns (periods ended 12/31/12)
Performance Table Uses Highest Federal Rate	rr_PerformanceTableUsesHighestFederalRate	After-tax returns are calculated using the historically highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes.
Performance Table Not Relevant to Tax Deferred	rr_PerformanceTableNotRelevantToTaxDeferred	Actual after-tax returns depend on your individual tax situation and may differ from those shown in the preceding table. The after-tax return information shown above does not apply to Fund shares held through a tax-deferred account, such as a 401(k) plan or an IRA.
Performance Table Narrative	rr_PerformanceTableNarrativeTextBlock	Effective February 15, 2013, the Fund’s primary benchmark index changed from the S&P 500® Index to the Morgan Stanley Capital International (“MSCI”) All Country World IndexSM to reflect the global investment strategies of the Fund. Additionally, the Fund changed the name of its secondary benchmark index from Moderate Allocation Index to Global Moderate Allocation Index and its composition from an internally-calculated, hypothetical combination of unmanaged indices that combines total returns from the Dow Jones Wilshire 5000 Index (40%), the Barclays U.S. Aggregate Bond Index (40%), the MSCI EAFE® Index (18%), and the MSCI Emerging Markets Free IndexSM (2%) to an internally-calculated, hypothetical combination of unmanaged indices that combines total returns from the MSCI All Country World IndexSM (60%) and the Barclays Global Aggregate Bond Index (40%). The MSCI All Country World IndexSM is an unmanaged, free float-adjusted market capitalization weighted index that is designed to measure the equity market performance of global developed and emerging markets. Janus Capital believes that the foregoing benchmark index changes provide a more appropriate representation of the Fund’s revised investment strategy that includes an increased focus on global investments, including emerging markets. After-tax returns are calculated using distributions for the Fund’s Class D Shares for the periods following February 16, 2010; and for the Fund’s Class J Shares, the predecessor share class, for the periods prior to February 16, 2010. If Class D Shares of the Fund had been available during these earlier periods, distributions may have been different and thus, after-tax returns may have been different from those shown. After-tax returns are calculated using the historically highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes. Actual after-tax returns depend on your individual tax situation and may differ from those shown in the preceding table. The after-tax return information shown above does not apply to Fund shares held through a tax-deferred account, such as a 401(k) plan or an IRA.
Performance Table Closing [Text Block]	rr_PerformanceTableClosingTextBlock	Updated performance information is available at janus.com/allfunds or by calling 1-800-525-3713.
Janus Global Allocation Fund - Moderate | Class D Shares | Class D
Risk/Return:	rr_RiskReturnAbstract
Operating Expenses Column [Text]	rr_OperatingExpensesColumnName	Class D
Management Fees	rr_ManagementFeesOverAssets	0.05%
Other Expenses	rr_OtherExpensesOverAssets	0.20%
Acquired Fund Fees and Expenses	rr_AcquiredFundFeesAndExpensesOverAssets	0.65%
Total Annual Fund Operating Expenses	rr_ExpensesOverAssets	0.90%
Expense Example, By Year, Column [Text]	rr_ExpenseExampleByYearColumnName	Class D Shares
1 Year	rr_ExpenseExampleYear01	$ 92
3 Years	rr_ExpenseExampleYear03	287
5 Years	rr_ExpenseExampleYear05	498
10 Years	rr_ExpenseExampleYear10	$ 1,108
2006	rr_AnnualReturn2006	14.28%
2007	rr_AnnualReturn2007	12.71%
2008	rr_AnnualReturn2008	(25.28%)
2009	rr_AnnualReturn2009	30.34%
2010	rr_AnnualReturn2010	12.31%
2011	rr_AnnualReturn2011	(2.55%)
2012	rr_AnnualReturn2012	12.74%
Bar Chart, Year to Date Return, Date	rr_BarChartYearToDateReturnDate	Sep. 30, 2013
Bar Chart, Year to Date Return	rr_BarChartYearToDateReturn	9.53%
Highest Quarterly Return, Label	rr_HighestQuarterlyReturnLabel	Best Quarter:
Highest Quarterly Return, Date	rr_BarChartHighestQuarterlyReturnDate	Jun. 30, 2009
Highest Quarterly Return	rr_BarChartHighestQuarterlyReturn	14.27%
Lowest Quarterly Return, Label	rr_LowestQuarterlyReturnLabel	Worst Quarter:
Lowest Quarterly Return, Date	rr_BarChartLowestQuarterlyReturnDate	Dec. 31, 2008
Lowest Quarterly Return	rr_BarChartLowestQuarterlyReturn	(11.62%)
Janus Global Allocation Fund - Moderate | Class D Shares | Return Before Taxes | Class D
Risk/Return:	rr_RiskReturnAbstract
Column	rr_AverageAnnualReturnColumnName	Class D Shares
Label	rr_AverageAnnualReturnLabel	Return Before Taxes
1 Year	rr_AverageAnnualReturnYear01	12.74%
5 Years	rr_AverageAnnualReturnYear05	3.74%
Since Inception	rr_AverageAnnualReturnSinceInception	6.44%
Inception Date	rr_AverageAnnualReturnInceptionDate	Dec. 30, 2005
Janus Global Allocation Fund - Moderate | Class D Shares | Return After Taxes on Distributions | Class D
Risk/Return:	rr_RiskReturnAbstract
Column	rr_AverageAnnualReturnColumnName	Class D Shares
Label	rr_AverageAnnualReturnLabel	Return After Taxes on Distributions
1 Year	rr_AverageAnnualReturnYear01	12.01%
5 Years	rr_AverageAnnualReturnYear05	2.96%
Since Inception	rr_AverageAnnualReturnSinceInception	5.61%
Inception Date	rr_AverageAnnualReturnInceptionDate	Dec. 30, 2005
Janus Global Allocation Fund - Moderate | Class D Shares | Return After Taxes on Distributions and Sale of Fund Shares | Class D
Risk/Return:	rr_RiskReturnAbstract
Column	rr_AverageAnnualReturnColumnName	Class D Shares
Label	rr_AverageAnnualReturnLabel	Return After Taxes on Distributions and Sale of Fund Shares
1 Year	rr_AverageAnnualReturnYear01	8.51%
5 Years	rr_AverageAnnualReturnYear05	2.77%
Since Inception	rr_AverageAnnualReturnSinceInception	5.14%
Inception Date	rr_AverageAnnualReturnInceptionDate	Dec. 30, 2005
Janus Global Allocation Fund - Moderate | Class D Shares | Morgan Stanley Capital International All Country World Index℠ (net of foreign withholding taxes) (reflects no deduction for expenses, fees, or taxes, except foreign withholding taxes)
Risk/Return:	rr_RiskReturnAbstract
Label	rr_AverageAnnualReturnLabel	Morgan Stanley Capital International All Country World IndexSM (net of foreign withholding taxes)
1 Year	rr_AverageAnnualReturnYear01	16.13%
5 Years	rr_AverageAnnualReturnYear05	(1.16%)
Since Inception	rr_AverageAnnualReturnSinceInception	3.52%
Inception Date	rr_AverageAnnualReturnInceptionDate	Dec. 30, 2005
Janus Global Allocation Fund - Moderate | Class D Shares | Global Moderate Allocation Index (reflects no deduction for expenses, fees, or taxes, except any applicable foreign withholding taxes)
Risk/Return:	rr_RiskReturnAbstract
Label	rr_AverageAnnualReturnLabel	Global Moderate Allocation Index
1 Year	rr_AverageAnnualReturnYear01	11.45%
5 Years	rr_AverageAnnualReturnYear05	1.89%
Since Inception	rr_AverageAnnualReturnSinceInception	4.95%
Inception Date	rr_AverageAnnualReturnInceptionDate	Dec. 30, 2005
Janus Global Allocation Fund - Moderate | Class D Shares | S&P 500® Index (reflects no deduction for expenses, fees, or taxes)
Risk/Return:	rr_RiskReturnAbstract
Label	rr_AverageAnnualReturnLabel	S&P 500® Index
1 Year	rr_AverageAnnualReturnYear01	16.00%
5 Years	rr_AverageAnnualReturnYear05	1.66%
Since Inception	rr_AverageAnnualReturnSinceInception	4.12%
Inception Date	rr_AverageAnnualReturnInceptionDate	Dec. 30, 2005
Janus Global Allocation Fund - Moderate | Class D Shares | Moderate Allocation Index (reflects no deduction for expenses, fees, or taxes, except any applicable foreign withholding taxes)
Risk/Return:	rr_RiskReturnAbstract
Label	rr_AverageAnnualReturnLabel	Moderate Allocation Index
1 Year	rr_AverageAnnualReturnYear01	11.74%
5 Years	rr_AverageAnnualReturnYear05	3.14%
Since Inception	rr_AverageAnnualReturnSinceInception	5.21%
Inception Date	rr_AverageAnnualReturnInceptionDate	Dec. 30, 2005

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Janus High-Yield Fund | Class A, C, S, I, N, R, T Shares

FUND SUMMARY

Janus High-Yield Fund

INVESTMENT OBJECTIVES

Janus High-Yield Fund seeks to obtain high current income.

Capital appreciation is a secondary investment objective when consistent with its primary investment objective.

FEES AND EXPENSES OF THE FUND

This table describes the fees and expenses that you may pay if you buy and hold Shares of the Fund. Each share class has different expenses, but represents an investment in the same Fund.

For Class A Shares, you may qualify for sales charge discounts if you and your family invest, or agree to invest in the future, at least $50,000 in the Fund or in other Janus mutual funds. More information about these and other discounts, as well as eligibility requirements for each share class, is available from your financial professional and in the “Purchases” section on page 64 of the Fund’s Prospectus and in the “Purchases” section on page 70 of the Fund’s Statement of Additional Information.

SHAREHOLDER FEES
(fees paid directly from your investment)

Shareholder Fees Janus High-Yield Fund Class A, C, S, I, N, R, T Shares	Class A	Class C	Class S	Class I	Class N	Class R	Class T
Shareholder Fees Column [Text]	Class A	Class C	Class S	Class I	Class N	Class R	Class T
Maximum Sales Charge (load) Imposed on Purchases (as a percentage of offering price)	4.75%	none	none	none	none	none	none
Maximum Deferred Sales Charge (load) (as a percentage of the lower of original purchase price or redemption proceeds)	none	1.00%	none	none	none	none	none

ANNUAL FUND OPERATING EXPENSES
(expenses that you pay each year as a percentage of the value of your investment)

Annual Fund Operating Expenses Janus High-Yield Fund Class A, C, S, I, N, R, T Shares	Class A	Class C	Class S	Class I	Class N	Class R	Class T
Operating Expenses Column [Text]	Class A	Class C	Class S	Class I	Class N	Class R	Class T
Management Fees	0.56%	0.56%	0.56%	0.56%	0.56%	0.56%	0.56%
Distribution/Service (12b-1) Fees	0.25%	1.00%	0.25%	none	none	0.50%	none
Other Expenses	0.16%	0.16%	0.31%	0.12%	0.05%	0.31%	0.31%
Total Annual Fund Operating Expenses	0.97%	1.72%	1.12%	0.68%	0.61%	1.37%	0.87%

EXAMPLE:

The Example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds.

The Example assumes that you invest $10,000 in the Fund for the time periods indicated and reinvest all dividends and distributions. The Example also assumes that your investment has a 5% return each year and that the Fund’s operating expenses remain the same. Although your actual costs may be higher or lower, based on these assumptions your costs would be:

If Shares are redeemed:

Expense Example Janus High-Yield Fund Class A, C, S, I, N, R, T Shares (USD $)	Expense Example, By Year, Column [Text]	1 Year	3 Years	5 Years	10 Years
Class A	Class A Shares	569	769	986	1,608
Class C	Class C Shares	275	542	933	2,030
Class S	Class S Shares	114	356	617	1,363
Class I	Class I Shares	69	218	379	847
Class N	Class N Shares	62	195	340	762
Class R	Class R Shares	139	434	750	1,646
Class T	Class T Shares	89	278	482	1,073

If Shares are not redeemed:

Expense Example, No Redemption Janus High-Yield Fund Class A, C, S, I, N, R, T Shares (USD $)	Expense Example, No Redemption, By Year, Column [Text]	1 Year	3 Years	5 Years	10 Years
Class A	Class A Shares	569	769	986	1,608
Class C	Class C Shares	175	542	933	2,030
Class S	Class S Shares	114	356	617	1,363
Class I	Class I Shares	69	218	379	847
Class N	Class N Shares	62	195	340	762
Class R	Class R Shares	139	434	750	1,646
Class T	Class T Shares	89	278	482	1,073

Portfolio Turnover: 

The Fund pays transaction costs, such as commissions, when it buys and sells securities (or “turns over” its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when Fund shares are held in a taxable account. These costs, which are not reflected in annual fund operating expenses or in the Example, affect the Fund’s performance. During the most recent fiscal year, the Fund’s portfolio turnover rate was 93% of the average value of its portfolio.

PRINCIPAL INVESTMENT STRATEGIES

The Fund pursues its investment objectives by investing, under normal circumstances, at least 80% of its net assets in high-yield/high-risk securities rated below investment grade. Securities rated below investment grade may include their unrated equivalents or other high-yielding securities the portfolio managers believe offer attractive risk/return characteristics. The Fund may at times invest all of its assets in such securities. The Fund may also invest in bank loans, money market instruments, and foreign debt securities (which may include investments in emerging markets). Due to the nature of securities in which the Fund invests, it may have relatively high portfolio turnover compared to other funds.

In addition, the Fund may invest its assets in derivatives, which are instruments that have a value derived from, or directly linked to, an underlying asset, such as equity securities, fixed-income securities, commodities, currencies, interest rates, or market indices. In particular, the Fund may use interest rate futures to manage portfolio risk. The Fund’s exposure to derivatives will vary. For purposes of meeting its 80% investment policy, the Fund may include derivatives that have characteristics similar to the securities in which the Fund may directly invest.

In addition to considering economic factors such as the effect of interest rates on the Fund’s investments, the portfolio managers apply a “bottom up” approach in choosing investments. This means that the portfolio managers look at income-producing securities one at a time to determine if a security is an attractive investment opportunity and if it is consistent with the Fund’s investment policies.

The Fund may lend portfolio securities on a short-term or long-term basis, in an amount equal to up to 1/3 of its total assets as determined at the time of the loan origination.

PRINCIPAL INVESTMENT RISKS

Although the Fund may be less volatile than funds that invest most of their assets in common stocks, the Fund’s returns and yields will vary, and you could lose money.

Fixed-Income Securities Risk. The Fund invests in a variety of fixed-income securities. Typically, the values of fixed-income securities change inversely with prevailing interest rates. Therefore, a fundamental risk of fixed-income securities is interest rate risk, which is the risk that the value of such securities will generally decline as prevailing interest rates rise, which may cause the Fund’s net asset value to likewise decrease. How specific fixed-income securities may react to changes in interest rates will depend on the specific characteristics of each security. Fixed-income securities are also subject to credit risk, prepayment risk, valuation risk, and liquidity risk. Credit risk is the risk that the credit strength of an issuer of a fixed-income security will weaken and/or that the issuer will be unable to make timely principal and interest payments and that the security may go into default. Prepayment risk is the risk that during periods of falling interest rates, certain fixed-income securities with higher interest rates, such as mortgage- and asset-backed securities, may be prepaid by their issuers thereby reducing the amount of interest payments. Valuation risk is the risk that one or more of the fixed-income securities in which the Fund invests are priced differently than the value realized upon such security’s sale. In times of market instability, valuation may be more difficult. Liquidity risk is the risk that fixed-income securities may be difficult or impossible to sell at the time that the portfolio managers would like or at the price the portfolio managers believe the security is currently worth.

High-Yield/High-Risk Bond Risk. The Fund may invest without limit in higher-yielding/higher-risk bonds, also known as “junk” bonds. High-yield/high-risk bonds may be more sensitive than other types of bonds to economic changes, political changes, or adverse developments specific to the company that issued the bond, which may adversely affect their value.

Bank Loan Risk. Bank loans are obligations of companies or other entities entered into in connection with recapitalizations, acquisitions, and refinancings. The Fund’s investments in bank loans are generally acquired as a participation interest in, or assignment of, loans originated by a lender or other financial institution. These investments may include institutionally-traded floating and fixed-rate debt securities. Participation interests and assignments involve credit, interest rate, and liquidity risk. In addition, the bank loans underlying these securities often involve borrowers with low credit ratings whose financial conditions are troubled or uncertain, including companies that are highly leveraged or in bankruptcy proceedings.

Foreign Exposure Risk. The Fund may have exposure to foreign markets as a result of its investments in foreign securities, including investments in emerging markets, which can be more volatile than the U.S. markets. As a result, its returns and net asset value may be affected to a large degree by fluctuations in currency exchange rates or political or economic conditions in a particular country. In some foreign markets, there may not be protection against failure by other parties to complete transactions. It may not be possible for the Fund to repatriate capital, dividends, interest, and other income from a particular country or governmental entity. In addition, a market swing in one or more countries or regions where the Fund has invested a significant amount of its assets may have a greater effect on the Fund’s performance than it would in a more geographically diversified portfolio. To the extent the Fund invests in foreign debt securities, such investments are sensitive to changes in interest rates. Additionally, investments in securities of foreign governments involve the risk that a foreign government may not be willing or able to pay interest or repay principal when due. The Fund’s investments in emerging market countries may involve risks greater than, or in addition to, the risks of investing in more developed countries.

Portfolio Turnover Risk. Increased portfolio turnover may result in higher costs, which may have a negative effect on the Fund’s performance. In addition, higher portfolio turnover may result in the acceleration of capital gains and the recognition of greater levels of short-term capital gains, which are taxed at ordinary federal income tax rates when distributed to shareholders.

Derivatives Risk. Derivatives can be highly volatile and involve risks in addition to the risks of the underlying referenced securities. Gains or losses from a derivative investment can be substantially greater than the derivative’s original cost, and can therefore involve leverage. Leverage may cause the Fund to be more volatile than if it had not used leverage. Derivatives can be less liquid than other types of investments and entail the risk that the counterparty will default on its payment obligations.

Securities Lending Risk. The Fund may seek to earn additional income through lending its securities to certain qualified broker-dealers and institutions. There is the risk that when portfolio securities are lent, the securities may not be returned on a timely basis, and the Fund may experience delays and costs in recovering the security or gaining access to the collateral provided to the Fund to collateralize the loan. If the Fund is unable to recover a security on loan, the Fund may use the collateral to purchase replacement securities in the market. There is a risk that the value of the collateral could decrease below the cost of the replacement security by the time the replacement investment is made, resulting in a loss to the Fund.

An investment in the Fund is not a bank deposit and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency.

PERFORMANCE INFORMATION

The following information provides some indication of the risks of investing in the Fund by showing how the Fund’s performance has varied over time. Class T Shares (formerly named Class J Shares, the initial share class) of the Fund commenced operations with the Fund’s inception. Class A Shares, Class C Shares, Class S Shares, Class I Shares, and Class R Shares of the Fund commenced operations on July 6, 2009. Class N Shares of the Fund commenced operations on May 31, 2012.

• The performance shown for Class T Shares is calculated using the fees and expenses of Class T Shares in effect during the periods shown, net of any applicable fee and expense limitations or waivers.
• The performance shown for Class A Shares, Class C Shares, Class S Shares, and Class R Shares for periods prior to July 6, 2009, reflects the performance of the Fund’s former Class J Shares, calculated using the fees and expenses of each respective share class, without the effect of any fee and expense limitations or waivers.
• The performance shown for Class I Shares for periods prior to July 6, 2009, reflects the performance of the Fund’s former Class J Shares, calculated using the fees and expenses of Class J Shares, net of any applicable fee and expense limitations or waivers.
• The performance shown for Class N Shares for periods prior to May 31, 2012, reflects the performance of the Fund’s Class T Shares, calculated using the fees and expenses of Class T Shares, net of any applicable fee and expense limitations or waivers.

If Class A Shares, Class C Shares, Class S Shares, Class I Shares, and Class R Shares of the Fund had been available during periods prior to July 6, 2009, or Class N Shares of the Fund had been available during periods prior to May 31, 2012, the performance shown for each respective share class may have been different. The performance shown for periods following the Fund’s commencement of Class A Shares, Class C Shares, Class S Shares, Class I Shares, Class N Shares, and Class R Shares reflects the fees and expenses of each respective share class, net of any applicable fee and expense limitations or waivers.

The bar chart depicts the change in performance from year to year during the periods indicated. The bar chart figures do not include any applicable sales charges that an investor may pay when they buy or sell Class A Shares or Class C Shares of the Fund. If sales charges were included, the returns would be lower. The table compares the Fund’s average annual returns for the periods indicated to a broad-based securities market index. The index is not actively managed and is not available for direct investment. All figures assume reinvestment of dividends and distributions. For certain periods, the Fund’s performance reflects the effect of expense waivers. Without the effect of these expense waivers, the performance shown would have been lower.

The Fund’s past performance (before and after taxes) does not necessarily indicate how it will perform in the future. Updated performance information is available at janus.com/advisor/mutual-funds or by calling 1-877-335-2687.

Annual Total Returns for Class T Shares (calendar year-end)

Best Quarter:  Second Quarter 2009  14.93%          Worst Quarter:  Fourth Quarter 2008  −12.96%

The Fund’s year-to-date return as of the calendar quarter ended September 30, 2013 was 3.54%.

Average Annual Total Returns (periods ended 12/31/12)

Average Annual Total Returns Janus High-Yield Fund Class A, C, S, I, N, R, T Shares	Column	Label		1 Year	5 Years	10 Years	Since Inception	Inception Date
Class T Return Before Taxes	Class T Shares	Return Before Taxes		14.30%	9.18%	8.59%	8.20%	Dec. 29, 1995
Class T Return After Taxes on Distributions	Class T Shares	Return After Taxes on Distributions		11.64%	5.95%	5.65%	4.95%	Dec. 29, 1995
Class T Return After Taxes on Distributions and Sale of Fund Shares	Class T Shares	Return After Taxes on Distributions and Sale of Fund Shares	[1]	9.23%	5.85%	5.58%	4.98%	Dec. 29, 1995
Class A Return Before Taxes	Class A Shares	Return Before Taxes	[2]	8.65%	8.00%	7.97%	7.84%	Dec. 29, 1995
Class C Return Before Taxes	Class C Shares	Return Before Taxes	[3]	12.25%	8.28%	7.74%	7.38%	Dec. 29, 1995
Class S Return Before Taxes	Class S Shares	Return Before Taxes		13.88%	8.87%	8.28%	7.92%	Dec. 29, 1995
Class I Return Before Taxes	Class I Shares	Return Before Taxes		14.37%	9.18%	8.59%	8.20%	Dec. 29, 1995
Class N Return Before Taxes	Class N Shares	Return Before Taxes		14.30%	9.18%	8.59%	8.20%	Dec. 29, 1995
Class R Return Before Taxes	Class R Shares	Return Before Taxes		13.69%	8.58%	8.01%	7.65%	Dec. 29, 1995
Barclays U.S. Corporate High-Yield Bond Index (reflects no deduction for expenses, fees, or taxes)		Barclays U.S. Corporate High-Yield Bond Index		15.81%	10.34%	10.62%	7.66%	Dec. 29, 1995

After-tax returns are calculated using distributions for the Fund’s Class T Shares (formerly named Class J Shares, the initial share class). After-tax returns are calculated using the historically highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes. Actual after-tax returns depend on your individual tax situation and may differ from those shown in the preceding table. The after-tax return information shown above does not apply to Fund shares held through a tax-deferred account, such as a 401(k) plan or an IRA.

After-tax returns are only shown for Class T Shares of the Fund. After-tax returns for the other classes of Shares will vary from those shown for Class T Shares due to varying sales charges (as applicable), fees, and expenses among the classes.

[1] If the Fund incurs a loss, which generates a tax benefit, the Return After Taxes on Distributions and Sale of Fund Shares may exceed the Fund’s other return figures.

[2] Calculated assuming maximum permitted sales loads.

[3] The one year return is calculated to include the contingent deferred sales charge.

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INTECH Global Dividend Fund | Class D Shares

FUND SUMMARY

INTECH Global Dividend Fund

INVESTMENT OBJECTIVE

INTECH Global Dividend Fund seeks long-term growth of capital and income.

FEES AND EXPENSES OF THE FUND

This table describes the fees and expenses that you may pay if you buy and hold Shares of the Fund.

ANNUAL FUND OPERATING EXPENSES
(expenses that you pay each year as a percentage of the value of your investment)

Annual Fund Operating Expenses		INTECH Global Dividend Fund Class D Shares Class D
Operating Expenses Column [Text]		Class D
Management Fees		0.55%
Other Expenses		2.02%
Total Annual Fund Operating Expenses	[1]	2.57%
Fee Waiver	[1]	1.92%
Total Annual Fund Operating Expenses After Fee Waiver	[1]	0.65%

EXAMPLE:

The following Example is based on expenses without waivers. The Example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds.

The Example assumes that you invest $10,000 in the Fund for the time periods indicated, reinvest all dividends and distributions, and then redeem all of your Shares at the end of each period. The Example also assumes that your investment has a 5% return each year and that the Fund’s operating expenses without waivers or recoupments (if applicable) remain the same. Although your actual costs may be higher or lower, based on these assumptions your costs would be:

Expense Example (USD $)	Expense Example, By Year, Column [Text]	1 Year	3 Years	5 Years	10 Years
Class D Shares INTECH Global Dividend Fund	Class D Shares	260	799	1,365	2,905

Portfolio Turnover: 

The Fund pays transaction costs, such as commissions, when it buys and sells securities (or “turns over” its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when Fund shares are held in a taxable account. These costs, which are not reflected in annual fund operating expenses or in the Example, affect the Fund’s performance. During the most recent fiscal year, the Fund’s portfolio turnover rate was 116% of the average value of its portfolio.

PRINCIPAL INVESTMENT STRATEGIES

The Fund invests, under normal circumstances, at least 80% of its net assets in dividend-paying securities. The Fund invests primarily in common stocks from the universe of the Morgan Stanley Capital International (“MSCI”) World High Dividend Yield Index, utilizing INTECH’s mathematical investment process. The MSCI World High Dividend Yield Index is designed to reflect the performance of the high dividend yield securities contained within the broader MSCI World Index^SM. The Fund may also invest in foreign equity and debt securities.

The Fund pursues its investment objective by applying a mathematical investment process to construct an investment portfolio from the universe of common stocks within its named benchmark index. The goal of this process is to build a portfolio of stocks in a more efficient combination than the named benchmark index. The process seeks to capitalize on the natural volatility of the market by searching for stocks within the index that have high relative volatility (providing the potential for excess returns) but that essentially move in opposite directions or have low correlation to each other (providing the potential for lower relative risk). By constructing the portfolio in this manner and periodically rebalancing the portfolio to maintain potentially more efficient weightings, INTECH’s mathematical investment process seeks to create a portfolio that, over time, produces returns in excess of its named benchmark index with risks similar to that of the benchmark index. The rebalancing techniques used by INTECH may result in a higher portfolio turnover compared to a “buy and hold” fund strategy.

The Fund may lend portfolio securities on a short-term or long-term basis, in an amount equal to up to 1/3 of its total assets as determined at the time of the loan origination.

PRINCIPAL INVESTMENT RISKS

The biggest risk is that the Fund’s returns will vary, and you could lose money. The Fund is designed for long-term investors seeking an equity portfolio, including common stocks. Common stocks tend to be more volatile than many other investment choices.

Foreign Exposure Risk. The Fund normally has significant exposure to foreign markets as a result of its investments in foreign securities, which can be more volatile than the U.S. markets. As a result, its returns and net asset value may be affected to a large degree by fluctuations in currency exchange rates or political or economic conditions in a particular country. In some foreign markets, there may not be protection against failure by other parties to complete transactions. It may not be possible for the Fund to repatriate capital, dividends, interest, and other income from a particular country or governmental entity. In addition, a market swing in one or more countries or regions where the Fund has invested a significant amount of its assets may have a greater effect on the Fund’s performance than it would in a more geographically diversified portfolio. To the extent the Fund invests in foreign debt securities, such investments are sensitive to changes in interest rates. Additionally, investments in securities of foreign governments involve the risk that a foreign government may not be willing or able to pay interest or repay principal when due.

Eurozone Risk. A number of countries in the European Union (“EU”) have experienced severe economic and financial difficulties. As a result, financial markets in the EU have been subject to extreme volatility and declines in asset values and liquidity. Responses to these financial problems by European governments, central banks, and others, including austerity measures and reforms, may not work, may result in social unrest, and may limit future growth and economic recovery or have other unintended consequences. Further defaults or restructurings by governments and others of their debt could have additional adverse effects on economies, financial markets, and asset valuations around the world. To the extent that the Fund has exposure to European markets or to transactions tied to the value of the euro, these events could negatively affect the value and liquidity of the Fund’s investments.

Dividend Risk. Companies that issue dividend-yielding securities are not required to continue to pay dividends on such securities. Therefore, there is the possibility that such companies could reduce or eliminate the payment of dividends in the future.

Market Risk. The value of the Fund’s portfolio may decrease if the value of an individual company or security, or multiple companies or securities, in the portfolio decreases. Further, regardless of how well individual companies or securities perform, the value of the Fund’s portfolio could also decrease if there are deteriorating economic or market conditions. It is important to understand that the value of your investment may fall, sometimes sharply, in response to changes in the market, and you could lose money.

Investment Process Risk. The proprietary mathematical investment process used by INTECH may not achieve the desired results. There is a risk that INTECH’s method of identifying stocks with higher volatility than the named benchmark index or its method of identifying stocks that tend to move in the same or opposite direction relative to each other (correlation) will not result in selecting stocks with continuing volatility or the expected correlation. In INTECH’s history, which spans more than 25 years, INTECH’s mathematical investment process has experienced periods of both underperformance and outperformance relative to an identified benchmark. Even when the proprietary mathematical investment process is working appropriately, INTECH expects that there will be periods of underperformance relative to the benchmark. On an occasional basis, INTECH makes changes to its mathematical investment process. These changes may result in changes to the portfolio, might not provide the intended results, and may adversely impact the Fund’s performance.

Portfolio Turnover Risk. Increased portfolio turnover may result in higher costs, which may have a negative effect on the Fund’s performance. In addition, higher portfolio turnover may result in the acceleration of capital gains and the recognition of greater levels of short-term capital gains, which are taxed at ordinary federal income tax rates when distributed to shareholders.

Securities Lending Risk. The Fund may seek to earn additional income through lending its securities to certain qualified broker-dealers and institutions. There is the risk that when portfolio securities are lent, the securities may not be returned on a timely basis, and the Fund may experience delays and costs in recovering the security or gaining access to the collateral provided to the Fund to collateralize the loan. If the Fund is unable to recover a security on loan, the Fund may use the collateral to purchase replacement securities in the market. There is a risk that the value of the collateral could decrease below the cost of the replacement security by the time the replacement investment is made, resulting in a loss to the Fund.

An investment in the Fund is not a bank deposit and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency.

PERFORMANCE INFORMATION

The following information provides some indication of the risks of investing in the Fund by showing how the Fund’s performance has varied over time. The bar chart depicts the Fund’s performance during the period indicated. The table compares the Fund’s average annual returns for the periods indicated to broad-based securities market indices. The indices are not actively managed and are not available for direct investment. All figures assume reinvestment of dividends and distributions. For certain periods, the Fund’s performance reflects the effect of expense waivers. Without the effect of these expense waivers, the performance shown would have been lower.

The Fund’s past performance (before and after taxes) does not necessarily indicate how it will perform in the future. Updated performance information is available at janus.com/allfunds or by calling 1-800-525-3713.

Annual Total Returns for Class D Shares (calendar year-end)

Best Quarter:  Third Quarter 2012  5.87%          Worst Quarter:  Second Quarter 2012  −2.75%

The Fund’s year-to-date return as of the calendar quarter ended September 30, 2013 was 12.74%.

Average Annual Total Returns (periods ended 12/31/12)

Average Annual Total Returns INTECH Global Dividend Fund Class D Shares	Column	Label	1 Year	Since Inception	Inception Date
Class D Return Before Taxes	Class D Shares	Return Before Taxes	11.90%	14.70%	Dec. 15, 2011
Class D Return After Taxes on Distributions	Class D Shares	Return After Taxes on Distributions	11.19%	13.96%	Dec. 15, 2011
Class D Return After Taxes on Distributions and Sale of Fund Shares	Class D Shares	Return After Taxes on Distributions and Sale of Fund Shares	8.33%	12.30%	Dec. 15, 2011
Morgan Stanley Capital International World Index℠ (net of foreign withholding taxes) (reflects no deduction for expenses, fees, or taxes, except foreign withholding taxes)		Morgan Stanley Capital International World Index℠ (net of foreign withholding taxes)	15.83%	19.02%	Dec. 15, 2011
Morgan Stanley Capital International World High Dividend Yield Index (net of foreign withholding taxes) (reflects no deduction for expenses, fees, or taxes, except foreign withholding taxes)		Morgan Stanley Capital International World High Dividend Yield Index (net of foreign withholding taxes)	12.24%	15.80%	Dec. 15, 2011

After-tax returns are calculated using the historically highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes. Actual after-tax returns depend on your individual tax situation and may differ from those shown in the preceding table. The after-tax return information shown above does not apply to Fund shares held through a tax-deferred account, such as a 401(k) plan or an IRA.

[1] Janus Capital has contractually agreed to waive its investment advisory fee and/or reimburse Fund expenses to the extent that the Fund’s total annual fund operating expenses (excluding administrative services fees payable pursuant to the Transfer Agency Agreement, brokerage commissions, interest, dividends, taxes, acquired fund fees and expenses, and extraordinary expenses) exceed 0.50% until at least November 1, 2014. The contractual waiver may be terminated or modified prior to this date only at the discretion of the Board of Trustees. For a period of three years subsequent to the Fund’s commencement of operations (December 15, 2011), Janus Capital may recover from the Fund fees and expenses previously waived or reimbursed, which could then be considered a deferral, if the Fund’s expense ratio, including recovered expenses, falls below the expense limit.

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Janus Money Market Fund | Class D Shares

FUND SUMMARY

Janus Money Market Fund

INVESTMENT OBJECTIVES

Janus Money Market Fund seeks capital preservation and liquidity with current income as a secondary objective.

FEES AND EXPENSES OF THE FUND

This table describes the fees and expenses that you may pay if you buy and hold Shares of the Fund.

ANNUAL FUND OPERATING EXPENSES
(expenses that you pay each year as a percentage of the value of your investment)

Annual Fund Operating Expenses	Janus Money Market Fund Class D Shares Class D
Operating Expenses Column [Text]	Class D
Management Fees	0.20%
Other Expenses	0.47%
Total Annual Fund Operating Expenses	0.67%

EXAMPLE:

The Example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds.

The Example assumes that you invest $10,000 in the Fund for the time periods indicated, reinvest all dividends and distributions, and then redeem all of your Shares at the end of each period. The Example also assumes that your investment has a 5% return each year and that the Fund’s operating expenses remain the same. Although your actual costs may be higher or lower, based on these assumptions your costs would be:

Expense Example (USD $)	Expense Example, By Year, Column [Text]	1 Year	3 Years	5 Years	10 Years
Janus Money Market Fund Class D Shares Class D	Class D Shares	68	214	373	835

PRINCIPAL INVESTMENT STRATEGIES

The Fund pursues its investment objectives by investing primarily in high quality debt obligations and obligations of financial institutions. Debt obligations may include commercial paper, notes and bonds, and variable amount master demand notes. Obligations of financial institutions include certificates of deposit and time deposits. The Fund also intends to invest in repurchase agreements including those secured by U.S. Government agencies. Some government agencies backed by the full faith and credit of the United States are supported by the issuer’s ability to borrow from the United States Treasury, some are supported only by the credit of the issuer, and some are supported by the United States in some other way.

The Fund will:

• invest in high quality, short-term money market instruments that present minimal credit risks, as determined by Janus Capital

• invest only in U.S. dollar-denominated instruments that have a remaining maturity of 397 days or less (as calculated pursuant to Rule 2a-7 under the Investment Company Act of 1940, as amended)

• maintain a dollar-weighted average portfolio maturity of 60 days or less and maintain a dollar-weighted average portfolio life (portfolio maturity measured without reference to any maturity shortening provisions of adjustable rate securities by reference to their interest rate reset dates) of 120 days or less

PRINCIPAL INVESTMENT RISKS

Market Risk. The Fund’s yield will vary as the short-term securities in its portfolio mature and the proceeds are reinvested in securities with different interest rates. For capital preservation and liquidity, the Fund may have a greater concentration in short-term securities including, but not limited to, investing up to all of its assets in overnight securities, which may result in a reduction of the Fund's yield. Over time, the real value of the Fund's yield may be eroded by inflation. Although the Fund invests only in high-quality, short-term money market instruments, there is a risk that the value of the securities it holds will fall as a result of changes in interest rates, an issuer's actual or perceived creditworthiness, or an issuer's ability to meet its obligations. The credit quality of the Fund's holdings can change rapidly in certain market environments and any downgrade or default of a portfolio security could cause the Fund's share price or yield to fall.

Collateral Risk. With respect to collateral received in repurchase transactions or other investments, the Fund may have significant exposure to financial services, mortgage markets, and government agencies not secured by the full faith and credit of the United States. Such exposure, depending on market conditions, could have a negative impact on the Fund, including minimizing the value of any collateral.

Money Market Risk. An investment in the Fund is not a bank deposit and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency. Although the Fund seeks to preserve the value of your investment at $1.00 per share, it is possible to lose money by investing in the Fund.

PERFORMANCE INFORMATION

The following information provides some indication of the risks of investing in the Fund by showing how the Fund’s performance has varied over time. Class D Shares of the Fund commenced operations on February 16, 2010, as a result of the restructuring of Class J Shares, the predecessor share class. The performance shown for Class D Shares for periods prior to February 16, 2010, reflects the performance of the Fund’s former Class J Shares, calculated using the fees and expenses in effect during the periods shown, net of any applicable fee and expense limitations or waivers. If Class D Shares of the Fund had been available during periods prior to February 16, 2010, the performance shown may have been different. The performance shown for periods following the Fund’s commencement of Class D Shares reflects the fees and expenses of Class D Shares, net of any applicable fee and expense limitations or waivers.

The bar chart depicts the change in performance from year to year during the periods indicated. The table shows how the Fund’s returns over different periods average out. All figures assume reinvestment of dividends and distributions. For certain periods, the Fund’s performance reflects the effect of expense waivers. Without the effect of these expense waivers, the performance shown would have been lower.

The Fund’s past performance does not necessarily indicate how it will perform in the future. Updated performance information is available at janus.com/allfunds or by calling 1-800-525-3713.

Annual Total Returns for Class D Shares (calendar year-end)

Best Quarter:  Fourth Quarter 2006  1.23%          Worst Quarter:  Third Quarter 2011  0.00%

The Fund’s year-to-date return as of the calendar quarter ended September 30, 2013 was 0.00%.

Average Annual Total Returns (periods ended 12/31/12)

Average Annual Total Returns	Label	Column	1 Year	5 Years	10 Years	Since Inception	Inception Date
Janus Money Market Fund Class D Shares Class D Return Before Taxes	Return Before Taxes	Class D Shares	none	0.43%	1.59%	2.91%	Feb. 14, 1995

The 7-day yield on December 31, 2012 was 0.00% for Janus Money Market Fund.

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Janus Diversified Alternatives Fund | Class D Shares

FUND SUMMARY

Janus Diversified Alternatives Fund

INVESTMENT OBJECTIVE

Janus Diversified Alternatives Fund seeks absolute return with low correlation to stocks and bonds.

FEES AND EXPENSES OF THE FUND

This table describes the fees and expenses that you may pay if you buy and hold Shares of the Fund.

ANNUAL FUND OPERATING EXPENSES
(expenses that you pay each year as a percentage of the value of your investment)

Annual Fund Operating Expenses		Janus Diversified Alternatives Fund Class D Shares Class D
Operating Expenses Column [Text]		Class D
Management Fees of the Fund and the Subsidiary	[1]	1.00%
Other Expenses		1.17%
Other Expenses of the Fund	[2]	1.15%
Other Expenses of the Subsidiary		0.02%
Total Annual Fund Operating Expenses	[3]	2.17%
Fee Waiver	[3]	0.78%
Total Annual Fund Operating Expenses After Fee Waiver	[3]	1.39%

EXAMPLE:

The following Example is based on expenses without waivers. The Example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds.

The Example assumes that you invest $10,000 in the Fund for the time periods indicated, reinvest all dividends and distributions, and then redeem all of your Shares at the end of each period. The Example also assumes that your investment has a 5% return each year and that the Fund’s operating expenses without waivers or recoupments (if applicable) remain the same. Although your actual costs may be higher or lower, based on these assumptions your costs would be:

Expense Example (USD $)	Expense Example, By Year, Column [Text]	1 Year	3 Years	5 Years	10 Years
Janus Diversified Alternatives Fund Class D Shares Class D	Class D Shares	220	679	1,164	2,503

Portfolio Turnover: 

The Fund pays transaction costs, such as commissions, when it buys and sells securities (or “turns over” its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when Fund shares are held in a taxable account. These costs, which are not reflected in annual fund operating expenses or in the Example, affect the Fund’s performance. During the period December 28, 2012 to June 30, 2013, the Fund’s portfolio turnover rate was 38% of the average value of its portfolio.

PRINCIPAL INVESTMENT STRATEGIES

Under normal market conditions, the Fund pursues its investment objective by investing in a diverse group of return drivers, each a type of risk premium (collectively, “risk premia”), across equity, fixed income, commodity, and currency asset classes. Risk premia refers to the return that is expected for assuming a particular market risk. For example, investors expect a higher return in exchange for the perceived risks associated with investing in emerging markets as compared to investing in developed markets. Accordingly, a belief that emerging market equities may outperform developed market equities presents a risk premia opportunity. The Fund seeks to generate returns by identifying and isolating diverse sources of potential risk premia, and combining risk premia into a liquid portfolio that seeks to deliver consistent, absolute returns with a low correlation to the returns generated by investments in stocks and bonds. There is no guarantee that the portfolio will be successful in meeting this objective.

The Fund employs a proprietary multi-factor process to allocate the Fund’s assets across the various risk premia. The process begins with an approximate equal-weighted risk to each risk premium in which the Fund invests, so that no individual risk premium contributes disproportionately to the Fund’s overall risk profile and expected returns over the long term. Next, the Fund applies additional advanced allocation methodologies to the portfolio to tactically adjust the weights of risk premia. The Fund’s portfolio managers generally rebalance risk premia allocations quarterly, but may rebalance such allocations more often from time to time to adjust the Fund’s relative risk premia exposures. The rebalancing techniques used by the Fund’s portfolio managers may result in a higher portfolio turnover rate and related expenses compared to a “buy and hold” fund strategy. The Fund may not utilize all identified risk premia in its investment process at all times. Janus Capital believes that this allocation process may provide better risk adjusted returns than a traditional asset allocation strategy that employs fixed weights for asset classes.

The Fund employs various strategies within the equity, fixed income, commodity, and currency asset classes to identify risk premia and generate returns, including, but not limited to, relative value, momentum, credit, size, roll yield, systematic, and currency carry.

Relative Value – Relative Value investing seeks to capture the spread between a relatively undervalued asset and a more expensive one. For example, one pool of equities often outperforms another pool of equities in a different sector or investment style. Relative value attempts to identify the difference in valuation associated with those assets and favors investments in the relatively undervalued pool to generate return.

Momentum – Momentum investing seeks to capitalize on the expected continuance of trends in the market. For example, if interest rates are increasing, a momentum investor would invest in securities that would generate positive returns if rates continue to increase in the near term.

Credit – Credit investing seeks to invest in fixed-income securities to realize the additional rate of return that corporate debt provides as compared to U.S. Treasuries.

Size – Size investing seeks to generate returns by investing in small capitalization equity securities over large capitalization equity securities. The basis for this strategy is that over time, less liquid equities (small capitalization) will outperform more liquid equities (large capitalization).

Roll Yield – Roll Yield investing seeks to capture returns from favoring certain maturities of commodity futures contracts over others. This strategy typically combines offsetting long and short exposures on various sets of individual commodity futures contracts that have different expiration dates.

Systematic – Systematic investing seeks to invest in one or more asset classes, or a subset of a specific asset class, to generate the associated market return. For example, the Fund may invest a portion of the portfolio in global equities to generate the market returns associated with that type of investment.

Currency Carry – Currency Carry investing seeks to generate returns by investing in higher yielding currencies versus lower yielding currencies. In a carry trade, low interest rate currencies may be sold, and high interest rate currencies may be purchased.

As part of the process to identify and isolate specific risk premia and generate returns, the Fund may have both long and short exposure to securities in which it invests with respect to risk premia. The Fund’s exposure to U.S. and non-U.S. investments, which may include emerging markets, will vary based on perceived investment opportunities and the portfolio managers’ global investment outlook. The Fund will make significant use of derivative instruments, which are instruments that have a value derived from or directly linked to an underlying asset, such as equity securities, fixed-income securities, commodities, currencies, interest rates, or market indices. Derivatives will be used to gain exposure to the various asset classes in which the Fund may invest, to generate returns, for hedging purposes (to offset risks associated with an investment, currency exposure, or market conditions), to adjust currency exposure relative to a benchmark index, and to earn income and enhance returns. The Fund may utilize swaps, including equity, interest rate, currency, and total return swaps. The Fund may utilize options and futures, including forward commodity and currency contracts and U.S. Treasury, interest rate, and market index futures. The Fund’s use of options includes options purchased and sold (written). The Fund’s exposure to derivatives will vary and is not limited to those derivatives listed.

The Fund’s exposure to derivatives will create a leveraging effect on the portfolio where market exposure exceeds amounts invested. This leverage will vary over time and may at times be significant. The Fund may have a substantial cash position due to margin and collateral requirements related to the Fund’s use of derivatives. Such margin and collateral requirements may limit the Fund’s ability to take advantage of other investment opportunities and may negatively affect the Fund’s ability to achieve its investment objective.

The Fund’s equity and fixed-income exposure may be obtained through direct investment in equity and fixed-income securities or through investment in other mutual funds or exchange-traded funds (“ETFs”). The Fund may also utilize exchange-traded notes (“ETNs”). The equity securities in which the Fund invests may involve exposure to common stocks of companies of any size located anywhere in the world, from larger, well-established companies to smaller, emerging growth companies. The fixed-income securities in which the Fund invests may include securities of any maturity and of any credit quality, and may include exposure to government bonds, corporate bonds, convertible bonds, mortgage-backed securities, zero-coupon bonds, and high-yield/high-risk bonds, also known as “junk” bonds. The Fund’s investment in ETFs and ETNs may be used to gain exposure to market indices, a basket of securities, commodities, currencies, or a particular commodity or currency.

The Fund’s exposure to the commodity markets, in whole or in part, may be made through investment in a wholly-owned subsidiary of the Fund organized under the laws of the Cayman Islands (the “Subsidiary”), which is generally subject to the same investment policies and restrictions as the Fund. The Subsidiary will invest in commodity-related derivatives such as futures and swaps, ETNs, and other investments such as cash or U.S. Treasuries which may serve as margin or collateral for the Subsidiary’s commodity-linked derivative positions.

PRINCIPAL INVESTMENT RISKS

The biggest risk is that the Fund’s returns will vary, and you could lose money. The Fund is designed for long-term investors seeking a portfolio which includes exposure to equity (such as stocks or any other security representing an ownership interest), fixed-income (such as bonds, notes, and debentures), commodities, and currency asset classes, and which involves the use of derivatives. Such investments, and derivatives in particular, tend to be more volatile than many other investment choices.

Management Risk. The Fund’s ability to achieve its investment objective depends largely upon the portfolio managers’ successful evaluation of the risks, potential returns, and correlation properties with respect to the various risk premia in which the Fund invests. There is a risk that the returns provided by an individual risk premium may be subject to high volatility and that the portfolio managers’ beliefs about the risk, expected returns and correlation properties of various risk premia may be incorrect. Further, the Fund’s ability to achieve its investment objective also depends on the successful allocation of the Fund’s assets among various risk premia and asset classes, and you could lose money on your investment in the Fund as a result of these allocations. There is also a risk that the Fund’s investments will correlate with the performance of stocks and bonds to a greater degree than anticipated, and the Fund will not meet its investment objective. Finally, Janus Capital does not have prior experience managing a risk premia investment strategy, and there is no guarantee that the investment techniques and analysis used by the Fund’s portfolio managers will produce the desired results.

Market Risk. The value of the Fund’s portfolio may decrease if the value of an individual investment, or multiple investments, in the portfolio decreases at the same time. Further, while the Fund’s goal is to produce returns that have a low correlation to the stock and bond markets, you should understand that regardless of how well the Fund’s individual investments perform, the value of the Fund’s portfolio could also decrease if there are deteriorating economic or market conditions. The value of your investment in the Fund may fall, sometimes sharply, in response to changes in the market, and you could lose money. Because the Fund seeks to produce returns that have a low correlation to the returns generated by the stock and bond markets, the Fund may underperform these markets when these markets rise sharply or experience prolonged periods of outperformance. Additionally, the Fund’s performance may be negatively affected during prolonged periods when the returns provided by the risk premia are consistently low.

Derivatives Risk. Derivatives can be highly volatile and involve risks in addition to the risks of the underlying referenced securities. Gains or losses from a derivative investment can be substantially greater than the derivative’s original cost, and can therefore involve leverage. Leverage may cause the Fund to be more volatile than if it had not used leverage. Derivatives can be complex instruments and may involve analysis that differs from that required for other investment types used by the Fund. If the value of a derivative does not correlate well with the particular market or other asset class to which the derivative is intended to provide exposure, the derivative may not produce the anticipated result. Derivatives can also reduce the opportunity for gain or result in losses by offsetting positive returns in other investments. Derivatives can be less liquid than other types of investments and entail the risk that the counterparty will default on its payment obligations. If the counterparty to a derivative transaction defaults, the Fund would risk the loss of the net amount of the payments that it contractually is entitled to receive. To the extent the Fund enters into short derivative positions, the Fund may be exposed to risks similar to those associated with short sales, including the risk that the Fund’s losses are theoretically unlimited.

Leverage Risk. Engaging in transactions using leverage or those having a leveraging effect subjects the Fund to certain risks. Leverage can magnify the effect of any gains or losses, causing the Fund to be more volatile than if it had not been leveraged. Certain commodity-linked derivative investments may subject the Fund to leveraged market exposure to commodities. In addition, the Fund’s assets that are used as collateral to secure short sale transactions may decrease in value while the short positions are outstanding, which may force the Fund to use its other assets to increase collateral. There is no assurance that a leveraging strategy will be successful.

Short Sales Risk. Short sales are speculative transactions and involve special risks, including a greater reliance on the portfolio managers’ ability to accurately anticipate the future value of a security. The Fund will suffer a loss if it sells a security short and the value of the security rises rather than falls. The Fund’s losses are potentially unlimited in a short sale transaction. The use of short sales may also cause the Fund to have higher expenses than those of other funds. In addition, due to the investment process of long and short positions, the Fund may be subject to additional transaction costs that may lower the Fund’s returns. The Fund’s use of short sales may also have a leveraging effect on the Fund’s portfolio.

Counterparty Risk. Certain derivative and “over-the-counter” instruments, such as swaps and forwards, are subject to the risk that the other party to a contract will not fulfill its contractual obligations.

Commodity-Linked Investments Risk. The Fund may invest, directly or indirectly, in various commodity-linked investments that provide exposure to the commodities markets. Such exposure may subject the Fund to greater volatility than investments in traditional securities. The value of a given commodity-linked derivative investment typically is based upon the price movements of a physical commodity (such as heating oil, livestock, or agricultural products), a commodity futures contract or commodity index, or some other readily measurable economic variable. The value of commodity-linked derivative instruments may therefore be affected by changes in overall market movements, volatility of the underlying benchmark, changes in interest rates, or other factors affecting a particular industry or commodity such as drought, floods, weather, livestock disease, embargoes, tariffs, and international economic, political, and regulatory developments.

Subsidiary Risk. By investing in the Subsidiary, the Fund will be indirectly exposed to the risks associated with the Subsidiary’s investments, which are generally similar to those that are permitted to be held by the Fund. The Subsidiary is not registered under the Investment Company Act of 1940, as amended (the “1940 Act”), and is not subject to all of the provisions of the 1940 Act. The Internal Revenue Service (“IRS”) has previously issued a number of private letter rulings to mutual funds (but not the Fund), in which it ruled that income from a fund’s investment in a wholly-owned foreign subsidiary that invests in commodity-linked derivatives, such as the Subsidiary, constitutes qualifying income. The IRS has suspended issuance of any further private letter rulings pending a review of its position. A change in the IRS’ position or changes in the laws of the United States and/or the Cayman Islands could result in the inability of the Fund and/or the Subsidiary to operate as described in the Fund’s Prospectus and the Statement of Additional Information. Such changes could adversely affect the Fund’s ability to meet its investment objective and jeopardize the Fund’s status as a regulated investment company under the U.S. tax code, which in turn may subject the Fund to higher tax rates and/or penalties.

Foreign Exposure Risk. The Fund normally has exposure to foreign markets as a result of its investments in foreign securities, including investments in emerging markets, which can be more volatile than the U.S. markets. As a result, its returns and net asset value may be affected to a large degree by fluctuations in currency exchange rates or political or economic conditions in a particular country. In some foreign markets, there may not be protection against failure by other parties to complete transactions. It may not be possible for the Fund to repatriate capital, dividends, interest, and other income from a particular country or governmental entity. In addition, a market swing in one or more countries or regions where the Fund has invested a significant amount of its assets may have a greater effect on the Fund’s performance than it would in a more geographically diversified portfolio. To the extent the Fund invests in foreign debt securities, such investments are sensitive to changes in interest rates. Additionally, investments in securities of foreign governments involve the risk that a foreign government may not be willing or able to pay interest or repay principal when due. The Fund’s exposure to emerging market countries may involve risks greater than, or in addition to, the risks of investing in more developed countries.

Eurozone Risk. A number of countries in the European Union (“EU”) have experienced severe economic and financial difficulties. As a result, financial markets in the EU have been subject to extreme volatility and declines in asset values and liquidity. Responses to these financial problems by European governments, central banks, and others, including austerity measures and reforms, may not work, may result in social unrest, and may limit future growth and economic recovery or have other unintended consequences. Further defaults or restructurings by governments and others of their debt could have additional adverse effects on economies, financial markets, and asset valuations around the world. To the extent that the Fund has exposure to European markets or to transactions tied to the value of the euro, these events could negatively affect the value and liquidity of the Fund’s investments.

Emerging Markets Risk. The risks of foreign investing mentioned above are heightened when investing in emerging markets. Emerging markets securities involve a number of additional risks, which may result from less government supervision and regulation of business and industry practices (including the potential lack of strict finance and accounting controls and standards), stock exchanges, brokers, and listed companies, making these investments potentially more volatile in price and less liquid than investments in developed securities markets, resulting in greater risk to investors. There is a risk in developing countries that a future economic or political crisis could lead to price controls, forced mergers of companies, expropriation or confiscatory taxation, imposition or enforcement of foreign ownership limits, seizure, nationalization, or creation of government monopolies, any of which may have a detrimental effect on the Fund’s investments. In addition, the Fund’s investments may be denominated in foreign currencies and therefore, changes in the value of a country’s currency compared to the U.S. dollar may affect the value of the Fund’s investments. To the extent that the Fund invests a significant portion of its assets in the securities of issuers in or companies of a single country or region, it is more likely to be impacted by events or conditions affecting that country or region, which could have a negative impact on the Fund’s performance. Some of the risks of investing directly in foreign and emerging market securities may be reduced when the Fund invests indirectly in foreign securities through various other investment vehicles including derivatives, which also involve other risks.

Growth Securities Risk. The Fund invests in companies after assessing their growth potential. Securities of companies perceived to be “growth” companies may be more volatile than other stocks and may involve special risks. If the portfolio managers’ perception of a company’s growth potential is not realized, the securities purchased may not perform as expected, reducing the Fund’s returns. In addition, because different types of stocks tend to shift in and out of favor depending on market and economic conditions, “growth” stocks may perform differently from the market as a whole and other types of securities.

Fixed-Income Securities Risk. The Fund invests in a variety of fixed-income securities. Typically, the values of fixed-income securities change inversely with prevailing interest rates. Therefore, a fundamental risk of fixed-income securities is interest rate risk, which is the risk that the value of such securities will generally decline as prevailing interest rates rise, which may cause the Fund’s net asset value to likewise decrease. How specific fixed-income securities may react to changes in interest rates will depend on the specific characteristics of each security. Fixed-income securities are also subject to credit risk, prepayment risk, valuation risk, and liquidity risk. Credit risk is the risk that the credit strength of an issuer of a fixed-income security will weaken and/or that the issuer will be unable to make timely principal and interest payments and that the security may go into default. Prepayment risk is the risk that during periods of falling interest rates, certain fixed-income securities with higher interest rates, such as mortgage- and asset-backed securities, may be prepaid by their issuers thereby reducing the amount of interest payments. Valuation risk is the risk that one or more of the fixed-income securities in which the Fund invests are priced differently than the value realized upon such security’s sale. In times of market instability, valuation may be more difficult. Liquidity risk is the risk that fixed-income securities may be difficult or impossible to sell at the time that the portfolio managers would like or at the price the portfolio managers believe the security is currently worth.

Mortgage-Backed Securities Risk. Mortgage-backed securities are classified generally as either commercial mortgage-backed securities or residential mortgage-backed securities, each of which is subject to certain specific risks. Mortgage-backed securities tend to be more sensitive to changes in interest rates than other types of debt securities. Investments in mortgage-backed securities are subject to both extension risk, where borrowers extend the duration of their mortgages in times of rising interest rates, and prepayment risk, where borrowers pay off their mortgages sooner than expected in times of declining interest rates. These risks may reduce the Fund’s returns. In addition, investments in mortgage-backed securities, including those comprised of subprime mortgages, may be subject to a higher degree of credit risk, valuation risk, and liquidity risk than various other types of fixed-income securities.

Currency Risk. The Fund’s investments and strategies will involve exposure to foreign currencies. Currency risk is the risk that changes in the exchange rate between currencies will adversely affect the value (in U.S. dollar terms) of an investment. As long as the Fund holds a foreign security, its value will be affected by the value of the local currency relative to the U.S. dollar. When the Fund sells a foreign currency denominated security, its value may be worth less in U.S. dollars even if the security increases in value in its home country. U.S. dollar-denominated securities of foreign issuers may also be affected by currency risk, as the value of these securities may also be affected by changes in the issuer’s local currency. Additionally, and as a result of the Fund’s use of currency investment strategies, the Fund’s net currency positions may expose the Fund to losses independent of any securities positions.

High-Yield/High-Risk Bond Risk. High-yield/high-risk bonds may be more sensitive than other types of bonds to economic changes, political changes, or adverse developments specific to the company that issued the bond, which may adversely affect their value.

Portfolio Turnover Risk. Increased portfolio turnover may result in higher costs, which may have a negative effect on the Fund’s performance. In addition, higher portfolio turnover may result in the acceleration of capital gains and the recognition of greater levels of short-term capital gains, which are taxed at ordinary federal income tax rates when distributed to shareholders.

Exchange-Traded Funds Risk. The Fund may invest in ETFs, which are typically open-end investment companies that are traded on a national securities exchange. ETFs typically incur fees, such as investment advisory fees and other operating expenses that are separate from those of the Fund, which will be indirectly paid by the Fund. As a result, the cost of investing in the Fund may be higher than the cost of investing directly in ETFs and may be higher than other mutual funds that invest directly in stocks and bonds. Further, the price movement of an ETF may fluctuate against the underlying securities or commodities it tracks and may result in a loss. Because the value of ETF shares depends on the demand in the market, the Fund may not be able to purchase or sell an ETF at the most optimal time, which could adversely affect the Fund’s performance.

The ETFs in which the Fund invests are subject to specific risks, depending on the investment strategy of the ETF. In turn, the Fund will be subject to substantially the same risks as those associated with direct exposure to the securities or commodities held by the ETF. Because the Fund may invest in a broad range of ETFs, such risks may include, but are not limited to, leverage risk, foreign exposure risk, fixed-income risk, and commodity-linked investments risk.

Exchange-Traded Notes Risk. The Fund may invest in ETNs, which are debt securities whose returns are linked to a particular index. ETNs are typically linked to the performance of a commodities index that reflects the potential return on unleveraged investments in futures contracts of physical commodities, plus a specified rate of interest that could be earned on cash collateral. ETNs are subject to credit risk and counterparty risk. The value of an ETN may vary and may be influenced by time to maturity, level of supply and demand for the ETN, volatility and lack of liquidity in underlying commodities markets, changes in the applicable interest rates, changes in the issuer’s credit rating, and economic, legal, political, or geographic events that affect the referenced commodity. When the Fund invests in ETNs it will bear its proportionate share of any fees and expenses borne by the ETN. There may be restrictions on the Fund’s right to redeem its investment in an ETN, which is meant to be held until maturity. The Fund’s decision to sell its ETN holdings may be limited by the availability of a secondary market.

Nondiversification Risk. Although the Fund seeks diverse sources of potential return or risk premia, the Fund is classified as nondiversified under the 1940 Act. This gives the Fund’s portfolio managers more flexibility to hold larger positions in a smaller number of securities. As a result, an increase or decrease in the value of a single security held by the Fund may have a greater impact on the Fund’s net asset value and total return.

An investment in the Fund is not a bank deposit and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency.

PERFORMANCE INFORMATION

The Fund does not have a full calendar year of operations. Performance information for certain periods is included in the Fund’s first annual and/or semiannual report.

[1] The Fund may invest in commodity-linked investments through a wholly-owned subsidiary of the Fund that invests in commodity-linked investments. Janus Capital has contractually agreed that to the extent the Fund invests in the subsidiary, it shall not collect advisory fees from the Fund in an amount equal to the fee it collects from the subsidiary. The management fee waiver arrangement may not be discontinued by Janus Capital as long as its contract with the subsidiary is in place.

[2] Other Expenses are based on the estimated expenses that the Fund expects to incur.

[3] Janus Capital has contractually agreed to waive its investment advisory fee and/or reimburse Fund expenses to the extent that the Fund's total annual fund operating expenses, which include the other expenses of the subsidiary shown above (excluding administrative services fees payable pursuant to the Transfer Agency Agreement, brokerage commissions, interest, dividends, taxes, acquired fund fees and expenses, and extraordinary expenses) exceed 1.25% until at least November 1, 2014. The contractual waiver may be terminated or modified prior to this date only at the discretion of the Board of Trustees. For a period of three years subsequent to the Fund's commencement of operations (December 28, 2012) or until the Fund's assets exceed the first breakpoint in the investment advisory fee schedule, whichever occurs first, Janus Capital may recover from the Fund fees and expenses previously waived or reimbursed, which could then be considered a deferral, if the Fund's expense ratio, including recovered expenses, falls below the expense limit.

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Label	Element	Value
Risk/Return:	rr_RiskReturnAbstract
Registrant Name	dei_EntityRegistrantName	JANUS INVESTMENT FUND
Prospectus Date	rr_ProspectusDate	Oct. 28, 2013
Perkins Small Cap Value Fund | Class D Shares
Risk/Return:	rr_RiskReturnAbstract
Risk/Return [Heading]	rr_RiskReturnHeading	FUND SUMMARY Perkins Small Cap Value Fund
Objective [Heading]	rr_ObjectiveHeading	INVESTMENT OBJECTIVE
Objective, Primary [Text Block]	rr_ObjectivePrimaryTextBlock	Perkins Small Cap Value Fund seeks capital appreciation.
Expense [Heading]	rr_ExpenseHeading	FEES AND EXPENSES OF THE FUND
Expense Narrative [Text Block]	rr_ExpenseNarrativeTextBlock	This table describes the fees and expenses that you may pay if you buy and hold Shares of the Fund.
Operating Expenses Caption [Text]	rr_OperatingExpensesCaption	ANNUAL FUND OPERATING EXPENSES (expenses that you pay each year as a percentage of the value of your investment)
Portfolio Turnover [Heading]	rr_PortfolioTurnoverHeading	Portfolio Turnover:
Portfolio Turnover [Text Block]	rr_PortfolioTurnoverTextBlock	The Fund pays transaction costs, such as commissions, when it buys and sells securities (or “turns over” its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when Fund shares are held in a taxable account. These costs, which are not reflected in annual fund operating expenses or in the Example, affect the Fund’s performance. During the most recent fiscal year, the Fund’s portfolio turnover rate was 60% of the average value of its portfolio.
Portfolio Turnover, Rate	rr_PortfolioTurnoverRate	60.00%
Expense Example [Heading]	rr_ExpenseExampleHeading	EXAMPLE:
Expense Example by Year [Heading]	rr_ExpenseExampleByYearHeading	The Example assumes that you invest $10,000 in the Fund for the time periods indicated, reinvest all dividends and distributions, and then redeem all of your Shares at the end of each period. The Example also assumes that your investment has a 5% return each year and that the Fund’s operating expenses remain the same. Although your actual costs may be higher or lower, based on these assumptions your costs would be:
Expense Example Narrative [Text Block]	rr_ExpenseExampleNarrativeTextBlock	The Example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds.
Strategy [Heading]	rr_StrategyHeading	PRINCIPAL INVESTMENT STRATEGIES
Strategy Narrative [Text Block]	rr_StrategyNarrativeTextBlock	The Fund pursues its investment objective by investing primarily in the common stocks of small companies whose stock prices are believed to be undervalued by the Fund’s portfolio managers. The Fund invests, under normal circumstances, at least 80% of its net assets in equity securities of small companies whose market capitalization, at the time of initial purchase, is less than the 12-month average of the maximum market capitalization for companies included in the Russell 2000® Value Index. This average is updated monthly. The market capitalizations within the index will vary, but as of June 30, 2013, they ranged from approximately $23 million to $5.6 billion. The Fund may also invest in foreign equity and debt securities, which may include investments in emerging markets. The Fund may invest, under normal circumstances, up to 20% of its net assets in securities of companies having market capitalizations outside of the aforementioned market capitalization ranges. In addition, when the portfolio managers believe that market conditions are unfavorable for investing, or when they are otherwise unable to locate attractive investment opportunities, the Fund may invest up to 20% of its net assets in cash or similar investments. The Fund’s securities selection focuses on companies that are out of favor with markets or have not yet been discovered by the broader investment community. The Fund’s portfolio managers generally look for companies with: strong balance sheets and solid recurring free cash flows attractive relative and absolute valuation ratios or that have underperformed recently favorable reward to risk characteristics The portfolio managers’ philosophy is to weigh a security’s downside risk before considering its upside potential, which may help provide an element of capital preservation.
Risk [Heading]	rr_RiskHeading	PRINCIPAL INVESTMENT RISKS
Risk Narrative [Text Block]	rr_RiskNarrativeTextBlock	The biggest risk is that the Fund’s returns will vary, and you could lose money. The Fund is designed for long-term investors seeking an equity portfolio, including common stocks. Common stocks tend to be more volatile than many other investment choices. Value Investing Risk. Because different types of stocks tend to shift in and out of favor depending on market and economic conditions, “value” stocks may perform differently than other types of stocks and from the market as a whole, and can continue to be undervalued by the market for long periods of time. It is also possible that a value stock will never appreciate to the extent expected by the portfolio managers. When the Fund’s investments in cash or similar investments increase due to a lack of favorable investment opportunities or other extraordinary factors, the Fund may not participate in market advances or declines to the same extent that it would if the Fund had been fully invested. Market Risk. The value of the Fund’s portfolio may decrease if the value of an individual company or security, or multiple companies or securities, in the portfolio decreases or if the portfolio managers’ belief about a company’s intrinsic worth is incorrect. Further, regardless of how well individual companies or securities perform, the value of the Fund’s portfolio could also decrease if there are deteriorating economic or market conditions. It is important to understand that the value of your investment may fall, sometimes sharply, in response to changes in the market, and you could lose money. Small-Sized Companies Risk. The Fund’s investments in securities issued by small-sized companies, which can include smaller, start-up companies offering emerging products or services, may involve greater risks than are customarily associated with larger, more established companies. Securities issued by small-sized companies tend to be more volatile and somewhat more speculative than securities issued by larger or more established companies and may underperform as compared to the securities of larger companies. Real Estate Securities Risk. The Fund’s performance may be affected by the risks associated with investments in real estate-related companies. The value of real estate-related companies’ securities is sensitive to changes in real estate values and rental income, property taxes, interest rates, tax and regulatory requirements, supply and demand, and the management skill and creditworthiness of the company. Investments in real estate investment trusts (“REITs”) involve the same risks as other real estate investments. In addition, a REIT could fail to qualify for tax-free pass-through of its income under the Internal Revenue Code or fail to maintain its exemption from registration under the Investment Company Act of 1940, as amended, which could produce adverse economic consequences for the REIT and its investors, including the Fund. An investment in the Fund is not a bank deposit and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency.
Risk Lose Money [Text]	rr_RiskLoseMoney	The biggest risk is that the Fund’s returns will vary, and you could lose money.
Risk Not Insured Depository Institution [Text]	rr_RiskNotInsuredDepositoryInstitution	An investment in the Fund is not a bank deposit and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency.
Bar Chart and Performance Table [Heading]	rr_BarChartAndPerformanceTableHeading	PERFORMANCE INFORMATION
Performance Narrative [Text Block]	rr_PerformanceNarrativeTextBlock	The following information provides some indication of the risks of investing in the Fund by showing how the Fund’s performance has varied over time. Class D Shares of the Fund commenced operations on February 16, 2010, as a result of the restructuring of Class J Shares. The performance shown for Class D Shares for periods prior to February 16, 2010, reflects the performance of the Fund’s former Class J Shares (formerly named Investor Shares). For the periods prior to April 21, 2003, the performance shown for Class D Shares reflects the historical performance of Berger Small Cap Value Fund – Investor Shares (as a result of a prior reorganization of Berger Small Cap Value Fund – Investor Shares into the Fund’s former Class J Shares). If Class D Shares of the Fund had been available during periods prior to February 16, 2010, the performance shown may have been different. The performance shown for periods following the Fund’s commencement of Class D Shares reflects the fees and expenses of Class D Shares, net of any applicable fee and expense limitations or waivers. The bar chart depicts the change in performance from year to year during the periods indicated. The table compares the Fund’s average annual returns for the periods indicated to a broad-based securities market index. The index is not actively managed and is not available for direct investment. All figures assume reinvestment of dividends and distributions. For certain periods, the Fund’s performance reflects the effect of expense waivers. Without the effect of these expense waivers, the performance shown would have been lower. The Fund’s past performance (before and after taxes) does not necessarily indicate how it will perform in the future. Updated performance information is available at janus.com/allfunds or by calling 1-800-525-3713.
Performance Information Illustrates Variability of Returns [Text]	rr_PerformanceInformationIllustratesVariabilityOfReturns	The following information provides some indication of the risks of investing in the Fund by showing how the Fund’s performance has varied over time. The bar chart depicts the change in performance from year to year during the periods indicated.
Performance Additional Market Index [Text]	rr_PerformanceAdditionalMarketIndex	The table compares the Fund’s average annual returns for the periods indicated to a broad-based securities market index. The index is not actively managed and is not available for direct investment. All figures assume reinvestment of dividends and distributions.
Performance Availability Phone [Text]	rr_PerformanceAvailabilityPhone	1-800-525-3713
Performance Availability Website Address [Text]	rr_PerformanceAvailabilityWebSiteAddress	janus.com/allfunds
Performance Past Does Not Indicate Future [Text]	rr_PerformancePastDoesNotIndicateFuture	The Fund’s past performance (before and after taxes) does not necessarily indicate how it will perform in the future.
Bar Chart [Heading]	rr_BarChartHeading	Annual Total Returns for Class D Shares (calendar year-end)
Bar Chart Closing [Text Block]	rr_BarChartClosingTextBlock	Best Quarter:  Second Quarter 2009  23.04%          Worst Quarter:  Fourth Quarter 2008  −18.83%
Year to Date Return, Label	rr_YearToDateReturnLabel	The Fund’s year-to-date return as of the calendar quarter ended September 30, 2013 was 18.51%.
Performance Table Heading	rr_PerformanceTableHeading	Average Annual Total Returns (periods ended 12/31/12)
Performance Table Uses Highest Federal Rate	rr_PerformanceTableUsesHighestFederalRate	After-tax returns are calculated using the historically highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes.
Performance Table Not Relevant to Tax Deferred	rr_PerformanceTableNotRelevantToTaxDeferred	Actual after-tax returns depend on your individual tax situation and may differ from those shown in the preceding table. The after-tax return information shown above does not apply to Fund shares held through a tax-deferred account, such as a 401(k) plan or an IRA.
Performance Table Explanation after Tax Higher	rr_PerformanceTableExplanationAfterTaxHigher	If the Fund incurs a loss, which generates a tax benefit, the Return After Taxes on Distributions and Sale of Fund Shares may exceed the Fund’s other return figures.
Performance Table Narrative	rr_PerformanceTableNarrativeTextBlock	The Russell 2000® Value Index measures the performance of those Russell 2000® companies with lower price-to-book ratios and lower forecasted growth values. This index is used to calculate the performance fee adjustment. After-tax returns are calculated using distributions for the Fund’s Class D Shares for the periods following February 16, 2010; for the Fund’s Class J Shares (formerly named Investor Shares) for the period April 21, 2003 to February 16, 2010; and for Berger Small Cap Value Fund – Investor Shares for periods prior to April 21, 2003. If Class D Shares of the Fund had been available during these earlier periods, distributions may have been different and thus, after-tax returns may have been different from those shown. After-tax returns are calculated using the historically highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes. Actual after-tax returns depend on your individual tax situation and may differ from those shown in the preceding table. The after-tax return information shown above does not apply to Fund shares held through a tax-deferred account, such as a 401(k) plan or an IRA.
Performance Table Closing [Text Block]	rr_PerformanceTableClosingTextBlock	Updated performance information is available at janus.com/allfunds or by calling 1-800-525-3713.
Perkins Small Cap Value Fund | Class D Shares | Class D
Risk/Return:	rr_RiskReturnAbstract
Operating Expenses Column [Text]	rr_OperatingExpensesColumnName	Class D
Management Fees (may adjust up or down)	rr_ManagementFeesOverAssets	0.56%
Other Expenses	rr_OtherExpensesOverAssets	0.21%
Total Annual Fund Operating Expenses	rr_ExpensesOverAssets	0.77%
Expense Example, By Year, Column [Text]	rr_ExpenseExampleByYearColumnName	Class D Shares
1 Year	rr_ExpenseExampleYear01	$ 79
3 Years	rr_ExpenseExampleYear03	246
5 Years	rr_ExpenseExampleYear05	428
10 Years	rr_ExpenseExampleYear10	$ 954
2003	rr_AnnualReturn2003	36.78%
2004	rr_AnnualReturn2004	13.57%
2005	rr_AnnualReturn2005	8.90%
2006	rr_AnnualReturn2006	12.37%
2007	rr_AnnualReturn2007	2.97%
2008	rr_AnnualReturn2008	(21.79%)
2009	rr_AnnualReturn2009	36.59%
2010	rr_AnnualReturn2010	18.00%
2011	rr_AnnualReturn2011	(3.33%)
2012	rr_AnnualReturn2012	9.07%
Bar Chart, Year to Date Return, Date	rr_BarChartYearToDateReturnDate	Sep. 30, 2013
Bar Chart, Year to Date Return	rr_BarChartYearToDateReturn	18.51%
Highest Quarterly Return, Label	rr_HighestQuarterlyReturnLabel	Best Quarter:
Highest Quarterly Return, Date	rr_BarChartHighestQuarterlyReturnDate	Jun. 30, 2009
Highest Quarterly Return	rr_BarChartHighestQuarterlyReturn	23.04%
Lowest Quarterly Return, Label	rr_LowestQuarterlyReturnLabel	Worst Quarter:
Lowest Quarterly Return, Date	rr_BarChartLowestQuarterlyReturnDate	Dec. 31, 2008
Lowest Quarterly Return	rr_BarChartLowestQuarterlyReturn	(18.83%)
Perkins Small Cap Value Fund | Class D Shares | Return Before Taxes | Class D
Risk/Return:	rr_RiskReturnAbstract
Column	rr_AverageAnnualReturnColumnName	Class D Shares
Label	rr_AverageAnnualReturnLabel	Return Before Taxes
1 Year	rr_AverageAnnualReturnYear01	9.07%
5 Years	rr_AverageAnnualReturnYear05	5.86%
10 Years	rr_AverageAnnualReturnYear10	10.03%
Perkins Small Cap Value Fund | Class D Shares | Return After Taxes on Distributions | Class D
Risk/Return:	rr_RiskReturnAbstract
Column	rr_AverageAnnualReturnColumnName	Class D Shares
Label	rr_AverageAnnualReturnLabel	Return After Taxes on Distributions
1 Year	rr_AverageAnnualReturnYear01	8.19%
5 Years	rr_AverageAnnualReturnYear05	4.63%
10 Years	rr_AverageAnnualReturnYear10	8.12%
Perkins Small Cap Value Fund | Class D Shares | Return After Taxes on Distributions and Sale of Fund Shares | Class D
Risk/Return:	rr_RiskReturnAbstract
Column	rr_AverageAnnualReturnColumnName	Class D Shares
Label	rr_AverageAnnualReturnLabel	Return After Taxes on Distributions and Sale of Fund Shares	[1]
1 Year	rr_AverageAnnualReturnYear01	7.09%
5 Years	rr_AverageAnnualReturnYear05	4.69%
10 Years	rr_AverageAnnualReturnYear10	8.25%
Perkins Small Cap Value Fund | Class D Shares | Russell 2000® Value Index (reflects no deduction for expenses, fees, or taxes)
Risk/Return:	rr_RiskReturnAbstract
Label	rr_AverageAnnualReturnLabel	Russell 2000® Value Index
1 Year	rr_AverageAnnualReturnYear01	18.05%
5 Years	rr_AverageAnnualReturnYear05	3.55%
10 Years	rr_AverageAnnualReturnYear10	9.50%

[1] If the Fund incurs a loss, which generates a tax benefit, the Return After Taxes on Distributions and Sale of Fund Shares may exceed the Fund’s other return figures.

XML

Label	Element	Value
Risk/Return:	rr_RiskReturnAbstract
Registrant Name	dei_EntityRegistrantName	JANUS INVESTMENT FUND
Prospectus Date	rr_ProspectusDate	Oct. 28, 2013
Perkins Small Cap Value Fund | Class L Shares
Risk/Return:	rr_RiskReturnAbstract
Risk/Return [Heading]	rr_RiskReturnHeading	FUND SUMMARY Perkins Small Cap Value Fund
Objective [Heading]	rr_ObjectiveHeading	INVESTMENT OBJECTIVE
Objective, Primary [Text Block]	rr_ObjectivePrimaryTextBlock	Perkins Small Cap Value Fund seeks capital appreciation.
Expense [Heading]	rr_ExpenseHeading	FEES AND EXPENSES OF THE FUND
Expense Narrative [Text Block]	rr_ExpenseNarrativeTextBlock	This table describes the fees and expenses that you may pay if you buy and hold Shares of the Fund.
Operating Expenses Caption [Text]	rr_OperatingExpensesCaption	ANNUAL FUND OPERATING EXPENSES (expenses that you pay each year as a percentage of the value of your investment)
Portfolio Turnover [Heading]	rr_PortfolioTurnoverHeading	Portfolio Turnover:
Portfolio Turnover [Text Block]	rr_PortfolioTurnoverTextBlock	The Fund pays transaction costs, such as commissions, when it buys and sells securities (or “turns over” its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when Fund shares are held in a taxable account. These costs, which are not reflected in annual fund operating expenses or in the Example, affect the Fund’s performance. During the most recent fiscal year, the Fund’s portfolio turnover rate was 60% of the average value of its portfolio.
Portfolio Turnover, Rate	rr_PortfolioTurnoverRate	60.00%
Expense Example [Heading]	rr_ExpenseExampleHeading	EXAMPLE:
Expense Example by Year [Heading]	rr_ExpenseExampleByYearHeading	The Example assumes that you invest $10,000 in the Fund for the time periods indicated, reinvest all dividends and distributions, and then redeem all of your Shares at the end of each period. The Example also assumes that your investment has a 5% return each year and that the Fund’s operating expenses remain the same. Although your actual costs may be higher or lower, based on these assumptions your costs would be:
Expense Example Narrative [Text Block]	rr_ExpenseExampleNarrativeTextBlock	The Example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds.
Strategy [Heading]	rr_StrategyHeading	PRINCIPAL INVESTMENT STRATEGIES
Strategy Narrative [Text Block]	rr_StrategyNarrativeTextBlock	The Fund pursues its investment objective by investing primarily in the common stocks of small companies whose stock prices are believed to be undervalued by the Fund’s portfolio managers. The Fund invests, under normal circumstances, at least 80% of its net assets in equity securities of small companies whose market capitalization, at the time of initial purchase, is less than the 12-month average of the maximum market capitalization for companies included in the Russell 2000® Value Index. This average is updated monthly. The market capitalizations within the index will vary, but as of June 30, 2013, they ranged from approximately $23 million to $5.6 billion. The Fund may also invest in foreign equity and debt securities, which may include investments in emerging markets. The Fund may invest, under normal circumstances, up to 20% of its net assets in securities of companies having market capitalizations outside of the aforementioned market capitalization ranges. In addition, when the portfolio managers believe that market conditions are unfavorable for investing, or when they are otherwise unable to locate attractive investment opportunities, the Fund may invest up to 20% of its net assets in cash or similar investments. The Fund’s securities selection focuses on companies that are out of favor with markets or have not yet been discovered by the broader investment community. The Fund’s portfolio managers generally look for companies with: strong balance sheets and solid recurring free cash flows attractive relative and absolute valuation ratios or that have underperformed recently favorable reward to risk characteristics The portfolio managers’ philosophy is to weigh a security’s downside risk before considering its upside potential, which may help provide an element of capital preservation.
Risk [Heading]	rr_RiskHeading	PRINCIPAL INVESTMENT RISKS
Risk Narrative [Text Block]	rr_RiskNarrativeTextBlock	The biggest risk is that the Fund’s returns will vary, and you could lose money. The Fund is designed for long-term investors seeking an equity portfolio, including common stocks. Common stocks tend to be more volatile than many other investment choices. Value Investing Risk. Because different types of stocks tend to shift in and out of favor depending on market and economic conditions, “value” stocks may perform differently than other types of stocks and from the market as a whole, and can continue to be undervalued by the market for long periods of time. It is also possible that a value stock will never appreciate to the extent expected by the portfolio managers. When the Fund’s investments in cash or similar investments increase due to a lack of favorable investment opportunities or other extraordinary factors, the Fund may not participate in market advances or declines to the same extent that it would if the Fund had been fully invested. Market Risk. The value of the Fund’s portfolio may decrease if the value of an individual company or security, or multiple companies or securities, in the portfolio decreases or if the portfolio managers’ belief about a company’s intrinsic worth is incorrect. Further, regardless of how well individual companies or securities perform, the value of the Fund’s portfolio could also decrease if there are deteriorating economic or market conditions. It is important to understand that the value of your investment may fall, sometimes sharply, in response to changes in the market, and you could lose money. Small-Sized Companies Risk. The Fund’s investments in securities issued by small-sized companies, which can include smaller, start-up companies offering emerging products or services, may involve greater risks than are customarily associated with larger, more established companies. Securities issued by small-sized companies tend to be more volatile and somewhat more speculative than securities issued by larger or more established companies and may underperform as compared to the securities of larger companies. Real Estate Securities Risk. The Fund’s performance may be affected by the risks associated with investments in real estate-related companies. The value of real estate-related companies’ securities is sensitive to changes in real estate values and rental income, property taxes, interest rates, tax and regulatory requirements, supply and demand, and the management skill and creditworthiness of the company. Investments in real estate investment trusts (“REITs”) involve the same risks as other real estate investments. In addition, a REIT could fail to qualify for tax-free pass-through of its income under the Internal Revenue Code or fail to maintain its exemption from registration under the Investment Company Act of 1940, as amended, which could produce adverse economic consequences for the REIT and its investors, including the Fund. An investment in the Fund is not a bank deposit and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency.
Risk Lose Money [Text]	rr_RiskLoseMoney	The biggest risk is that the Fund’s returns will vary, and you could lose money.
Risk Not Insured Depository Institution [Text]	rr_RiskNotInsuredDepositoryInstitution	An investment in the Fund is not a bank deposit and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency.
Bar Chart and Performance Table [Heading]	rr_BarChartAndPerformanceTableHeading	PERFORMANCE INFORMATION
Performance Narrative [Text Block]	rr_PerformanceNarrativeTextBlock	The following information provides some indication of the risks of investing in the Fund by showing how the Fund’s performance has varied over time. The performance shown for periods following April 21, 2003, reflects the fees and expenses of Class L Shares (formerly named Institutional Shares), net of any applicable fee and expense limitations or waivers. For the periods prior to April 21, 2003, the performance shown for Class L Shares reflects the historical performance of Berger Small Cap Value Fund – Institutional Shares (as a result of a prior reorganization of Berger Small Cap Value Fund – Institutional Shares into the Fund’s Class L Shares). The bar chart depicts the change in performance from year to year during the periods indicated. The table compares the Fund’s average annual returns for the periods indicated to a broad-based securities market index. The index is not actively managed and is not available for direct investment. All figures assume reinvestment of dividends and distributions. For certain periods, the Fund’s performance reflects the effect of expense waivers. Without the effect of these expense waivers, the performance shown would have been lower. The Fund’s past performance (before and after taxes) does not necessarily indicate how it will perform in the future. Updated performance information is available at janus.com/advisor/mutual-funds or by calling 1-877-335-2687.
Performance Information Illustrates Variability of Returns [Text]	rr_PerformanceInformationIllustratesVariabilityOfReturns	The following information provides some indication of the risks of investing in the Fund by showing how the Fund’s performance has varied over time. The bar chart depicts the change in performance from year to year during the periods indicated.
Performance Additional Market Index [Text]	rr_PerformanceAdditionalMarketIndex	The table compares the Fund’s average annual returns for the periods indicated to a broad-based securities market index. The index is not actively managed and is not available for direct investment. All figures assume reinvestment of dividends and distributions.
Performance Availability Phone [Text]	rr_PerformanceAvailabilityPhone	1-877-335-2687
Performance Availability Website Address [Text]	rr_PerformanceAvailabilityWebSiteAddress	janus.com/advisor/mutual-funds
Performance Past Does Not Indicate Future [Text]	rr_PerformancePastDoesNotIndicateFuture	The Fund’s past performance (before and after taxes) does not necessarily indicate how it will perform in the future.
Bar Chart [Heading]	rr_BarChartHeading	Annual Total Returns for Class L Shares (calendar year-end)
Bar Chart Closing [Text Block]	rr_BarChartClosingTextBlock	Best Quarter:  Second Quarter 2009  23.27%          Worst Quarter:  Fourth Quarter 2008  −18.78%
Year to Date Return, Label	rr_YearToDateReturnLabel	The Fund’s year-to-date return as of the calendar quarter ended September 30, 2013 was 18.62%.
Performance Table Heading	rr_PerformanceTableHeading	Average Annual Total Returns (periods ended 12/31/12)
Performance Table Uses Highest Federal Rate	rr_PerformanceTableUsesHighestFederalRate	After-tax returns are calculated using the historically highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes.
Performance Table Not Relevant to Tax Deferred	rr_PerformanceTableNotRelevantToTaxDeferred	Actual after-tax returns depend on your individual tax situation and may differ from those shown in the preceding table. The after-tax return information shown above does not apply to Fund shares held through a tax-deferred account, such as a 401(k) plan or an IRA.
Performance Table Explanation after Tax Higher	rr_PerformanceTableExplanationAfterTaxHigher	If the Fund incurs a loss, which generates a tax benefit, the Return After Taxes on Distributions and Sale of Fund Shares may exceed the Fund’s other return figures.
Performance Table Narrative	rr_PerformanceTableNarrativeTextBlock	The Russell 2000® Value Index measures the performance of those Russell 2000® companies with lower price-to-book ratios and lower forecasted growth values. This index is used to calculate the performance fee adjustment. After-tax returns are calculated using distributions for the Fund’s Class L Shares (formerly named Institutional Shares) for the periods following April 21, 2003; and for Berger Small Cap Value Fund – Institutional Shares for periods prior to April 21, 2003. If Class L Shares of the Fund had been available during these earlier periods, distributions may have been different and thus, after-tax returns may have been different from those shown. After-tax returns are calculated using the historically highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes. Actual after-tax returns depend on your individual tax situation and may differ from those shown in the preceding table. The after-tax return information shown above does not apply to Fund shares held through a tax-deferred account, such as a 401(k) plan or an IRA.
Performance Table Closing [Text Block]	rr_PerformanceTableClosingTextBlock	Updated performance information is available at janus.com/advisor/mutual-funds or by calling 1-877-335-2687.
Perkins Small Cap Value Fund | Class L Shares | Class L
Risk/Return:	rr_RiskReturnAbstract
Operating Expenses Column [Text]	rr_OperatingExpensesColumnName	Class L
Management Fees (may adjust up or down)	rr_ManagementFeesOverAssets	0.56%
Other Expenses	rr_OtherExpensesOverAssets	0.27%
Total Annual Fund Operating Expenses	rr_ExpensesOverAssets	0.83%
Expense Example, By Year, Column [Text]	rr_ExpenseExampleByYearColumnName	Class L Shares
1 Year	rr_ExpenseExampleYear01	$ 85
3 Years	rr_ExpenseExampleYear03	265
5 Years	rr_ExpenseExampleYear05	460
10 Years	rr_ExpenseExampleYear10	$ 1,025
2003	rr_AnnualReturn2003	37.18%
2004	rr_AnnualReturn2004	13.80%
2005	rr_AnnualReturn2005	9.14%
2006	rr_AnnualReturn2006	12.57%
2007	rr_AnnualReturn2007	3.21%
2008	rr_AnnualReturn2008	(21.63%)
2009	rr_AnnualReturn2009	36.91%
2010	rr_AnnualReturn2010	18.18%
2011	rr_AnnualReturn2011	(3.18%)
2012	rr_AnnualReturn2012	9.25%
Bar Chart, Year to Date Return, Date	rr_BarChartYearToDateReturnDate	Sep. 30, 2013
Bar Chart, Year to Date Return	rr_BarChartYearToDateReturn	18.62%
Highest Quarterly Return, Label	rr_HighestQuarterlyReturnLabel	Best Quarter:
Highest Quarterly Return, Date	rr_BarChartHighestQuarterlyReturnDate	Jun. 30, 2009
Highest Quarterly Return	rr_BarChartHighestQuarterlyReturn	23.27%
Lowest Quarterly Return, Label	rr_LowestQuarterlyReturnLabel	Worst Quarter:
Lowest Quarterly Return, Date	rr_BarChartLowestQuarterlyReturnDate	Dec. 31, 2008
Lowest Quarterly Return	rr_BarChartLowestQuarterlyReturn	(18.78%)
Perkins Small Cap Value Fund | Class L Shares | Return Before Taxes | Class L
Risk/Return:	rr_RiskReturnAbstract
Column	rr_AverageAnnualReturnColumnName	Class L Shares
Label	rr_AverageAnnualReturnLabel	Return Before Taxes
1 Year	rr_AverageAnnualReturnYear01	9.25%
5 Years	rr_AverageAnnualReturnYear05	6.05%
10 Years	rr_AverageAnnualReturnYear10	10.26%
Perkins Small Cap Value Fund | Class L Shares | Return After Taxes on Distributions | Class L
Risk/Return:	rr_RiskReturnAbstract
Column	rr_AverageAnnualReturnColumnName	Class L Shares
Label	rr_AverageAnnualReturnLabel	Return After Taxes on Distributions
1 Year	rr_AverageAnnualReturnYear01	8.35%
5 Years	rr_AverageAnnualReturnYear05	4.80%
10 Years	rr_AverageAnnualReturnYear10	8.31%
Perkins Small Cap Value Fund | Class L Shares | Return After Taxes on Distributions and Sale of Fund Shares | Class L
Risk/Return:	rr_RiskReturnAbstract
Column	rr_AverageAnnualReturnColumnName	Class L Shares
Label	rr_AverageAnnualReturnLabel	Return After Taxes on Distributions and Sale of Fund Shares	[1]
1 Year	rr_AverageAnnualReturnYear01	7.22%
5 Years	rr_AverageAnnualReturnYear05	4.84%
10 Years	rr_AverageAnnualReturnYear10	8.43%
Perkins Small Cap Value Fund | Class L Shares | Russell 2000® Value Index (reflects no deduction for expenses, fees, or taxes)
Risk/Return:	rr_RiskReturnAbstract
Label	rr_AverageAnnualReturnLabel	Russell 2000® Value Index
1 Year	rr_AverageAnnualReturnYear01	18.05%
5 Years	rr_AverageAnnualReturnYear05	3.55%
10 Years	rr_AverageAnnualReturnYear10	9.50%

[1] If the Fund incurs a loss, which generates a tax benefit, the Return After Taxes on Distributions and Sale of Fund Shares may exceed the Fund’s other return figures.

XML

Janus Money Market Fund | Class T Shares

FUND SUMMARY

Janus Money Market Fund

INVESTMENT OBJECTIVES

Janus Money Market Fund seeks capital preservation and liquidity with current income as a secondary objective.

FEES AND EXPENSES OF THE FUND

This table describes the fees and expenses that you may pay if you buy and hold Shares of the Fund.

ANNUAL FUND OPERATING EXPENSES
(expenses that you pay each year as a percentage of the value of your investment)

Annual Fund Operating Expenses	Janus Money Market Fund Class T Shares Class T
Operating Expenses Column [Text]	Class T
Management Fees	0.20%
Other Expenses	0.49%
Total Annual Fund Operating Expenses	0.69%

EXAMPLE:

The Example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds.

The Example assumes that you invest $10,000 in the Fund for the time periods indicated, reinvest all dividends and distributions, and then redeem all of your Shares at the end of each period. The Example also assumes that your investment has a 5% return each year and that the Fund’s operating expenses remain the same. Although your actual costs may be higher or lower, based on these assumptions your costs would be:

Expense Example (USD $)	Expense Example, By Year, Column [Text]	1 Year	3 Years	5 Years	10 Years
Janus Money Market Fund Class T Shares Class T	Class T Shares	70	221	384	859

PRINCIPAL INVESTMENT STRATEGIES

The Fund pursues its investment objectives by investing primarily in high quality debt obligations and obligations of financial institutions. Debt obligations may include commercial paper, notes and bonds, and variable amount master demand notes. Obligations of financial institutions include certificates of deposit and time deposits. The Fund also intends to invest in repurchase agreements including those secured by U.S. Government agencies. Some government agencies backed by the full faith and credit of the United States are supported by the issuer’s ability to borrow from the United States Treasury, some are supported only by the credit of the issuer, and some are supported by the United States in some other way.

The Fund will:

• invest in high quality, short-term money market instruments that present minimal credit risks, as determined by Janus Capital

• invest only in U.S. dollar-denominated instruments that have a remaining maturity of 397 days or less (as calculated pursuant to Rule 2a-7 under the Investment Company Act of 1940, as amended)

• maintain a dollar-weighted average portfolio maturity of 60 days or less and maintain a dollar-weighted average portfolio life (portfolio maturity measured without reference to any maturity shortening provisions of adjustable rate securities by reference to their interest rate reset dates) of 120 days or less

PRINCIPAL INVESTMENT RISKS

Market Risk. The Fund’s yield will vary as the short-term securities in its portfolio mature and the proceeds are reinvested in securities with different interest rates. For capital preservation and liquidity, the Fund may have a greater concentration in short-term securities including, but not limited to, investing up to all of its assets in overnight securities, which may result in a reduction of the Fund’s yield. Over time, the real value of the Fund’s yield may be eroded by inflation. Although the Fund invests only in high-quality, short-term money market instruments, there is a risk that the value of the securities it holds will fall as a result of changes in interest rates, an issuer’s actual or perceived creditworthiness, or an issuer’s ability to meet its obligations. The credit quality of the Fund’s holdings can change rapidly in certain market environments and any downgrade or default of a portfolio security could cause the Fund’s share price or yield to fall.

Collateral Risk. With respect to collateral received in repurchase transactions or other investments, the Fund may have significant exposure to financial services, mortgage markets, and government agencies not secured by the full faith and credit of the United States. Such exposure, depending on market conditions, could have a negative impact on the Fund, including minimizing the value of any collateral.

Money Market Risk. An investment in the Fund is not a bank deposit and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency. Although the Fund seeks to preserve the value of your investment at $1.00 per share, it is possible to lose money by investing in the Fund.

PERFORMANCE INFORMATION

The following information provides some indication of the risks of investing in the Fund by showing how the Fund’s performance has varied over time. Class T Shares (formerly named Class J Shares, the initial share class) of the Fund commenced operations with the Fund’s inception. The performance shown for Class T Shares is calculated using the fees and expenses of Class T Shares in effect during the periods shown, net of any applicable fee and expense limitations or waivers.

The bar chart depicts the change in performance from year to year during the periods indicated. The table shows how the Fund’s returns over different periods average out. All figures assume reinvestment of dividends and distributions. For certain periods, the Fund’s performance reflects the effect of expense waivers. Without the effect of these expense waivers, the performance shown would have been lower.

The Fund’s past performance does not necessarily indicate how it will perform in the future. Updated performance information is available at janus.com/advisor/mutual-funds or by calling 1-877-335-2687.

Annual Total Returns for Class T Shares (calendar year-end)

Best Quarter:  Fourth Quarter  2006  1.23%          Worst Quarter:  Third Quarter 2011  0.00%

The Fund’s year-to-date return as of the calendar quarter ended September 30, 2013 was 0.00%.

Average Annual Total Returns (periods ended 12/31/12)

Average Annual Total Returns	Column	Label	1 Year	5 Years	10 Years	Since Inception	Inception Date
Janus Money Market Fund Class T Shares Class T Return Before Taxes	Class T Shares	Return Before Taxes	none	0.43%	1.59%	2.91%	Feb. 14, 1995

The 7-day yield on December 31, 2012 was 0.00% for Janus Money Market Fund.

XML

Label	Element	Value
Risk/Return:	rr_RiskReturnAbstract
Registrant Name	dei_EntityRegistrantName	JANUS INVESTMENT FUND
Prospectus Date	rr_ProspectusDate	Oct. 28, 2013
INTECH International Fund | Class A, C, S, I, T Shares
Risk/Return:	rr_RiskReturnAbstract
Risk/Return [Heading]	rr_RiskReturnHeading	FUND SUMMARY INTECH International Fund
Objective [Heading]	rr_ObjectiveHeading	INVESTMENT OBJECTIVE
Objective, Primary [Text Block]	rr_ObjectivePrimaryTextBlock	INTECH International Fund seeks long-term growth of capital.
Expense [Heading]	rr_ExpenseHeading	FEES AND EXPENSES OF THE FUND
Expense Narrative [Text Block]	rr_ExpenseNarrativeTextBlock	This table describes the fees and expenses that you may pay if you buy and hold Shares of the Fund. Each share class has different expenses, but represents an investment in the same Fund.
Shareholder Fees Caption [Text]	rr_ShareholderFeesCaption	SHAREHOLDER FEES (fees paid directly from your investment)
Operating Expenses Caption [Text]	rr_OperatingExpensesCaption	ANNUAL FUND OPERATING EXPENSES (expenses that you pay each year as a percentage of the value of your investment)
Fee Waiver or Reimbursement over Assets, Date of Termination	rr_FeeWaiverOrReimbursementOverAssetsDateOfTermination	November 1, 2014
Portfolio Turnover [Heading]	rr_PortfolioTurnoverHeading	Portfolio Turnover:
Portfolio Turnover [Text Block]	rr_PortfolioTurnoverTextBlock	The Fund pays transaction costs, such as commissions, when it buys and sells securities (or “turns over” its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when Fund shares are held in a taxable account. These costs, which are not reflected in annual fund operating expenses or in the Example, affect the Fund’s performance. During the most recent fiscal year, the Fund’s portfolio turnover rate was 143% of the average value of its portfolio.
Portfolio Turnover, Rate	rr_PortfolioTurnoverRate	143.00%
Expense Breakpoint Discounts [Text]	rr_ExpenseBreakpointDiscounts	For Class A Shares, you may qualify for sales charge discounts if you and your family invest, or agree to invest in the future, at least $50,000 in the Fund or in other Janus mutual funds. More information about these and other discounts, as well as eligibility requirements for each share class, is available from your financial professional and in the “Purchases” section on page 51 of the Fund’s Prospectus and in the “Purchases” section on page 70 of the Fund’s Statement of Additional Information.
Expense Breakpoint, Minimum Investment Required [Amount]	rr_ExpenseBreakpointMinimumInvestmentRequiredAmount	$ 50,000
Expense Example [Heading]	rr_ExpenseExampleHeading	EXAMPLE:
Expense Example by Year [Heading]	rr_ExpenseExampleByYearHeading	The Example assumes that you invest $10,000 in the Fund for the time periods indicated and reinvest all dividends and distributions. The Example also assumes that your investment has a 5% return each year and that the Fund’s operating expenses without waivers remain the same. Although your actual costs may be higher or lower, based on these assumptions your costs would be:
Expense Example Narrative [Text Block]	rr_ExpenseExampleNarrativeTextBlock	The following Example is based on expenses without waivers. The Example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds.
Expense Example by, Year, Caption [Text]	rr_ExpenseExampleByYearCaption	If Shares are redeemed:
Expense Example, No Redemption, By Year, Caption [Text]	rr_ExpenseExampleNoRedemptionByYearCaption	If Shares are not redeemed:
Strategy [Heading]	rr_StrategyHeading	PRINCIPAL INVESTMENT STRATEGIES
Strategy Narrative [Text Block]	rr_StrategyNarrativeTextBlock	The Fund invests primarily in common stocks from the universe of the Morgan Stanley Capital International (“MSCI”) EAFE® (Europe, Australasia, Far East) Index, utilizing INTECH’s mathematical investment process. The MSCI EAFE® Index is an MSCI index that is designed to measure the performance of the developed markets of Europe, Australasia, and the Far East. The Fund may also invest in foreign equity and debt securities. The Fund pursues its investment objective by applying a mathematical investment process to construct an investment portfolio from the universe of common stocks within its named benchmark index. The goal of this process is to build a portfolio of stocks in a more efficient combination than the named benchmark index. The process seeks to capitalize on the natural volatility of the market by searching for stocks within the index that have high relative volatility (providing the potential for excess returns) but that essentially move in opposite directions or have low correlation to each other (providing the potential for lower relative risk). By constructing the portfolio in this manner and periodically rebalancing the portfolio to maintain potentially more efficient weightings, INTECH’s mathematical investment process seeks to create a portfolio that, over time, produces returns in excess of its named benchmark index with risks similar to that of the benchmark index. The rebalancing techniques used by INTECH may result in a higher portfolio turnover compared to a “buy and hold” fund strategy. The Fund may lend portfolio securities on a short-term or long-term basis, in an amount equal to up to 1/3 of its total assets as determined at the time of the loan origination.
Risk [Heading]	rr_RiskHeading	PRINCIPAL INVESTMENT RISKS
Risk Narrative [Text Block]	rr_RiskNarrativeTextBlock	The biggest risk is that the Fund’s returns will vary, and you could lose money. The Fund is designed for long-term investors seeking an equity portfolio, including common stocks. Common stocks tend to be more volatile than many other investment choices. Foreign Exposure Risk. The Fund normally has significant exposure to foreign markets as a result of its investments in foreign securities, which can be more volatile than the U.S. markets. As a result, its returns and net asset value may be affected to a large degree by fluctuations in currency exchange rates or political or economic conditions in a particular country. In some foreign markets, there may not be protection against failure by other parties to complete transactions. It may not be possible for the Fund to repatriate capital, dividends, interest, and other income from a particular country or governmental entity. In addition, a market swing in one or more countries or regions where the Fund has invested a significant amount of its assets may have a greater effect on the Fund’s performance than it would in a more geographically diversified portfolio. Eurozone Risk. A number of countries in the European Union (“EU”) have experienced severe economic and financial difficulties. As a result, financial markets in the EU have been subject to extreme volatility and declines in asset values and liquidity. Responses to these financial problems by European governments, central banks, and others, including austerity measures and reforms, may not work, may result in social unrest, and may limit future growth and economic recovery or have other unintended consequences. Further defaults or restructurings by governments and others of their debt could have additional adverse effects on economies, financial markets, and asset valuations around the world. To the extent that the Fund has exposure to European markets or to transactions tied to the value of the euro, these events could negatively affect the value and liquidity of the Fund’s investments. Market Risk. The value of the Fund’s portfolio may decrease if the value of an individual company or security, or multiple companies or securities, in the portfolio decreases. Further, regardless of how well individual companies or securities perform, the value of the Fund’s portfolio could also decrease if there are deteriorating economic or market conditions. It is important to understand that the value of your investment may fall, sometimes sharply, in response to changes in the market, and you could lose money. Investment Process Risk. The proprietary mathematical investment process used by INTECH may not achieve the desired results. There is a risk that INTECH’s method of identifying stocks with higher volatility than the named benchmark index or its method of identifying stocks that tend to move in the same or opposite direction relative to each other (correlation) will not result in selecting stocks with continuing volatility or the expected correlation. In INTECH’s history, which spans more than 25 years, INTECH’s mathematical investment process has experienced periods of both underperformance and outperformance relative to an identified benchmark. Even when the proprietary mathematical investment process is working appropriately, INTECH expects that there will be periods of underperformance relative to the benchmark. On an occasional basis, INTECH makes changes to its mathematical investment process. These changes may result in changes to the portfolio, might not provide the intended results, and may adversely impact the Fund’s performance. Real Estate Securities Risk. The Fund’s performance may be affected by the risks associated with investments in real estate-related companies. The value of real estate-related companies’ securities is sensitive to changes in real estate values and rental income, property taxes, interest rates, tax and regulatory requirements, supply and demand, and the management skill and creditworthiness of the company. Investments in real estate investment trusts (“REITs”) involve the same risks as other real estate investments. In addition, a REIT could fail to qualify for tax-free pass-through of its income under the Internal Revenue Code or fail to maintain its exemption from registration under the Investment Company Act of 1940, as amended, which could produce adverse economic consequences for the REIT and its investors, including the Fund. Portfolio Turnover Risk. Increased portfolio turnover may result in higher costs, which may have a negative effect on the Fund’s performance. In addition, higher portfolio turnover may result in the acceleration of capital gains and the recognition of greater levels of short-term capital gains, which are taxed at ordinary federal income tax rates when distributed to shareholders. Securities Lending Risk. The Fund may seek to earn additional income through lending its securities to certain qualified broker-dealers and institutions. There is the risk that when portfolio securities are lent, the securities may not be returned on a timely basis, and the Fund may experience delays and costs in recovering the security or gaining access to the collateral provided to the Fund to collateralize the loan. If the Fund is unable to recover a security on loan, the Fund may use the collateral to purchase replacement securities in the market. There is a risk that the value of the collateral could decrease below the cost of the replacement security by the time the replacement investment is made, resulting in a loss to the Fund. An investment in the Fund is not a bank deposit and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency.
Risk Lose Money [Text]	rr_RiskLoseMoney	The biggest risk is that the Fund’s returns will vary, and you could lose money.
Risk Not Insured Depository Institution [Text]	rr_RiskNotInsuredDepositoryInstitution	An investment in the Fund is not a bank deposit and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency.
Bar Chart and Performance Table [Heading]	rr_BarChartAndPerformanceTableHeading	PERFORMANCE INFORMATION
Performance Narrative [Text Block]	rr_PerformanceNarrativeTextBlock	The following information provides some indication of the risks of investing in the Fund by showing how the Fund’s performance has varied over time. Class I Shares, Class A Shares, Class C Shares, and Class S Shares of the Fund commenced operations on July 6, 2009, after the reorganization of each corresponding class of shares of Janus Adviser INTECH Risk-Managed International Fund (“JAD predecessor fund”) into each respective share class of the Fund. Class T Shares of the Fund commenced operations on July 6, 2009. The performance shown for Class I Shares, Class A Shares, Class C Shares, and Class S Shares for periods prior to July 6, 2009, reflects the historical performance of the JAD predecessor fund’s Class I Shares, Class A Shares, Class C Shares, and Class S Shares prior to the reorganization, calculated using the fees and expenses of each respective share class of the JAD predecessor fund, net of any applicable fee and expense limitations or waivers. The performance shown for Class T Shares for periods prior to July 6, 2009, reflects the historical performance of the JAD predecessor fund’s Class I Shares prior to the reorganization, calculated using the fees and expenses of Class T Shares, without the effect of any fee and expense limitations or waivers. If Class T Shares of the Fund had been available during periods prior to July 6, 2009, the performance shown may have been different. The performance shown for periods following the Fund’s commencement of Class I Shares, Class A Shares, Class C Shares, Class S Shares, and Class T Shares reflects the fees and expenses of each respective share class, net of any applicable fee and expense limitations or waivers. The bar chart depicts the change in performance from year to year during the periods indicated. The bar chart figures do not include any applicable sales charges that an investor may pay when they buy or sell Class A Shares or Class C Shares of the Fund. If sales charges were included, the returns would be lower. The table compares the Fund’s average annual returns for the periods indicated to a broad-based securities market index. The index is not actively managed and is not available for direct investment. All figures assume reinvestment of dividends and distributions. For certain periods, the Fund’s performance reflects the effect of expense waivers. Without the effect of these expense waivers, the performance shown would have been lower. The Fund’s past performance (before and after taxes) does not necessarily indicate how it will perform in the future. Updated performance information is available at janus.com/advisor/mutual-funds or by calling 1-877-335-2687.
Performance Information Illustrates Variability of Returns [Text]	rr_PerformanceInformationIllustratesVariabilityOfReturns	The following information provides some indication of the risks of investing in the Fund by showing how the Fund’s performance has varied over time. The bar chart depicts the change in performance from year to year during the periods indicated.
Performance Additional Market Index [Text]	rr_PerformanceAdditionalMarketIndex	The table compares the Fund’s average annual returns for the periods indicated to a broad-based securities market index. The index is not actively managed and is not available for direct investment. All figures assume reinvestment of dividends and distributions.
Performance Availability Phone [Text]	rr_PerformanceAvailabilityPhone	1-877-335-2687
Performance Availability Website Address [Text]	rr_PerformanceAvailabilityWebSiteAddress	janus.com/advisor/mutual-funds
Performance Past Does Not Indicate Future [Text]	rr_PerformancePastDoesNotIndicateFuture	The Fund’s past performance (before and after taxes) does not necessarily indicate how it will perform in the future.
Bar Chart [Heading]	rr_BarChartHeading	Annual Total Returns for Class I Shares (calendar year-end)
Bar Chart Does Not Reflect Sales Loads [Text]	rr_BarChartDoesNotReflectSalesLoads	The bar chart figures do not include any applicable sales charges that an investor may pay when they buy or sell Class A Shares or Class C Shares of the Fund. If sales charges were included, the returns would be lower.
Bar Chart Closing [Text Block]	rr_BarChartClosingTextBlock	Best Quarter:  Second Quarter 2009  22.50%          Worst Quarter:  Third Quarter 2008  −20.70%
Year to Date Return, Label	rr_YearToDateReturnLabel	The Fund’s year-to-date return as of the calendar quarter ended September 30, 2013 was 18.27%.
Performance Table Heading	rr_PerformanceTableHeading	Average Annual Total Returns (periods ended 12/31/12)
Performance Table Uses Highest Federal Rate	rr_PerformanceTableUsesHighestFederalRate	After-tax returns are calculated using the historically highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes.
Performance Table Not Relevant to Tax Deferred	rr_PerformanceTableNotRelevantToTaxDeferred	Actual after-tax returns depend on your individual tax situation and may differ from those shown in the preceding table. The after-tax return information shown above does not apply to Fund shares held through a tax-deferred account, such as a 401(k) plan or an IRA.
Performance Table One Class of after Tax Shown [Text]	rr_PerformanceTableOneClassOfAfterTaxShown	After-tax returns are only shown for Class I Shares of the Fund. After-tax returns for the other classes of Shares will vary from those shown for Class I Shares due to varying sales charges (as applicable), fees, and expenses among the classes.
Performance Table Explanation after Tax Higher	rr_PerformanceTableExplanationAfterTaxHigher	If the Fund incurs a loss, which generates a tax benefit, the Return After Taxes on Distributions and Sale of Fund Shares may exceed the Fund’s other return figures.
Performance Table Narrative	rr_PerformanceTableNarrativeTextBlock	After-tax returns are calculated using distributions for the Fund’s Class I Shares for periods following July 6, 2009; and for the JAD predecessor fund’s Class I Shares for periods prior to July 6, 2009. After-tax returns are calculated using the historically highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes. Actual after-tax returns depend on your individual tax situation and may differ from those shown in the preceding table. The after-tax return information shown above does not apply to Fund shares held through a tax-deferred account, such as a 401(k) plan or an IRA. After-tax returns are only shown for Class I Shares of the Fund. After-tax returns for the other classes of Shares will vary from those shown for Class I Shares due to varying sales charges (as applicable), fees, and expenses among the classes.
Performance Table Closing [Text Block]	rr_PerformanceTableClosingTextBlock	Updated performance information is available at janus.com/advisor/mutual-funds or by calling 1-877-335-2687.
INTECH International Fund | Class A, C, S, I, T Shares | Class A
Risk/Return:	rr_RiskReturnAbstract
Shareholder Fees Column [Text]	rr_ShareholderFeesColumnName	Class A
Maximum Sales Charge (load) Imposed on Purchases (as a percentage of offering price)	rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice	5.75%
Maximum Deferred Sales Charge (load) (as a percentage of the lower of original purchase price or redemption proceeds)	rr_MaximumDeferredSalesChargeOverOther	none
Operating Expenses Column [Text]	rr_OperatingExpensesColumnName	Class A
Management Fees	rr_ManagementFeesOverAssets	0.55%
Distribution/Service (12b-1) Fees	rr_DistributionAndService12b1FeesOverAssets	0.25%
Other Expenses	rr_OtherExpensesOverAssets	0.42%
Total Annual Fund Operating Expenses	rr_ExpensesOverAssets	1.22%	[1]
Fee Waiver	rr_FeeWaiverOrReimbursementOverAssets	none	[1]
Total Annual Fund Operating Expenses After Fee Waiver	rr_NetExpensesOverAssets	1.22%	[1]
Expense Example, By Year, Column [Text]	rr_ExpenseExampleByYearColumnName	Class A Shares
1 Year	rr_ExpenseExampleYear01	692
3 Years	rr_ExpenseExampleYear03	940
5 Years	rr_ExpenseExampleYear05	1,207
10 Years	rr_ExpenseExampleYear10	1,967
Expense Example, No Redemption, By Year, Column [Text]	rr_ExpenseExampleNoRedemptionByYearColumnName	Class A Shares
1 Year	rr_ExpenseExampleNoRedemptionYear01	692
3 Years	rr_ExpenseExampleNoRedemptionYear03	940
5 Years	rr_ExpenseExampleNoRedemptionYear05	1,207
10 Years	rr_ExpenseExampleNoRedemptionYear10	1,967
INTECH International Fund | Class A, C, S, I, T Shares | Class C
Risk/Return:	rr_RiskReturnAbstract
Shareholder Fees Column [Text]	rr_ShareholderFeesColumnName	Class C
Maximum Sales Charge (load) Imposed on Purchases (as a percentage of offering price)	rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice	none
Maximum Deferred Sales Charge (load) (as a percentage of the lower of original purchase price or redemption proceeds)	rr_MaximumDeferredSalesChargeOverOther	1.00%
Operating Expenses Column [Text]	rr_OperatingExpensesColumnName	Class C
Management Fees	rr_ManagementFeesOverAssets	0.55%
Distribution/Service (12b-1) Fees	rr_DistributionAndService12b1FeesOverAssets	1.00%
Other Expenses	rr_OtherExpensesOverAssets	0.60%
Total Annual Fund Operating Expenses	rr_ExpensesOverAssets	2.15%	[1]
Fee Waiver	rr_FeeWaiverOrReimbursementOverAssets	0.04%	[1]
Total Annual Fund Operating Expenses After Fee Waiver	rr_NetExpensesOverAssets	2.11%	[1]
Expense Example, By Year, Column [Text]	rr_ExpenseExampleByYearColumnName	Class C Shares
1 Year	rr_ExpenseExampleYear01	318
3 Years	rr_ExpenseExampleYear03	673
5 Years	rr_ExpenseExampleYear05	1,154
10 Years	rr_ExpenseExampleYear10	2,483
Expense Example, No Redemption, By Year, Column [Text]	rr_ExpenseExampleNoRedemptionByYearColumnName	Class C Shares
1 Year	rr_ExpenseExampleNoRedemptionYear01	218
3 Years	rr_ExpenseExampleNoRedemptionYear03	673
5 Years	rr_ExpenseExampleNoRedemptionYear05	1,154
10 Years	rr_ExpenseExampleNoRedemptionYear10	2,483
INTECH International Fund | Class A, C, S, I, T Shares | Class S
Risk/Return:	rr_RiskReturnAbstract
Shareholder Fees Column [Text]	rr_ShareholderFeesColumnName	Class S
Maximum Sales Charge (load) Imposed on Purchases (as a percentage of offering price)	rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice	none
Maximum Deferred Sales Charge (load) (as a percentage of the lower of original purchase price or redemption proceeds)	rr_MaximumDeferredSalesChargeOverOther	none
Operating Expenses Column [Text]	rr_OperatingExpensesColumnName	Class S
Management Fees	rr_ManagementFeesOverAssets	0.55%
Distribution/Service (12b-1) Fees	rr_DistributionAndService12b1FeesOverAssets	0.25%
Other Expenses	rr_OtherExpensesOverAssets	0.68%
Total Annual Fund Operating Expenses	rr_ExpensesOverAssets	1.48%	[1]
Fee Waiver	rr_FeeWaiverOrReimbursementOverAssets	none	[1]
Total Annual Fund Operating Expenses After Fee Waiver	rr_NetExpensesOverAssets	1.48%	[1]
Expense Example, By Year, Column [Text]	rr_ExpenseExampleByYearColumnName	Class S Shares
1 Year	rr_ExpenseExampleYear01	151
3 Years	rr_ExpenseExampleYear03	468
5 Years	rr_ExpenseExampleYear05	808
10 Years	rr_ExpenseExampleYear10	1,768
Expense Example, No Redemption, By Year, Column [Text]	rr_ExpenseExampleNoRedemptionByYearColumnName	Class S Shares
1 Year	rr_ExpenseExampleNoRedemptionYear01	151
3 Years	rr_ExpenseExampleNoRedemptionYear03	468
5 Years	rr_ExpenseExampleNoRedemptionYear05	808
10 Years	rr_ExpenseExampleNoRedemptionYear10	1,768
INTECH International Fund | Class A, C, S, I, T Shares | Class I
Risk/Return:	rr_RiskReturnAbstract
Shareholder Fees Column [Text]	rr_ShareholderFeesColumnName	Class I
Maximum Sales Charge (load) Imposed on Purchases (as a percentage of offering price)	rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice	none
Maximum Deferred Sales Charge (load) (as a percentage of the lower of original purchase price or redemption proceeds)	rr_MaximumDeferredSalesChargeOverOther	none
Operating Expenses Column [Text]	rr_OperatingExpensesColumnName	Class I
Management Fees	rr_ManagementFeesOverAssets	0.55%
Distribution/Service (12b-1) Fees	rr_DistributionAndService12b1FeesOverAssets	none
Other Expenses	rr_OtherExpensesOverAssets	0.37%
Total Annual Fund Operating Expenses	rr_ExpensesOverAssets	0.92%	[1]
Fee Waiver	rr_FeeWaiverOrReimbursementOverAssets	none	[1]
Total Annual Fund Operating Expenses After Fee Waiver	rr_NetExpensesOverAssets	0.92%	[1]
Expense Example, By Year, Column [Text]	rr_ExpenseExampleByYearColumnName	Class I Shares
1 Year	rr_ExpenseExampleYear01	94
3 Years	rr_ExpenseExampleYear03	293
5 Years	rr_ExpenseExampleYear05	509
10 Years	rr_ExpenseExampleYear10	1,131
Expense Example, No Redemption, By Year, Column [Text]	rr_ExpenseExampleNoRedemptionByYearColumnName	Class I Shares
1 Year	rr_ExpenseExampleNoRedemptionYear01	94
3 Years	rr_ExpenseExampleNoRedemptionYear03	293
5 Years	rr_ExpenseExampleNoRedemptionYear05	509
10 Years	rr_ExpenseExampleNoRedemptionYear10	1,131
2008	rr_AnnualReturn2008	(41.75%)
2009	rr_AnnualReturn2009	25.53%
2010	rr_AnnualReturn2010	9.76%
2011	rr_AnnualReturn2011	(13.48%)
2012	rr_AnnualReturn2012	17.03%
Bar Chart, Year to Date Return, Date	rr_BarChartYearToDateReturnDate	Sep. 30, 2013
Bar Chart, Year to Date Return	rr_BarChartYearToDateReturn	18.27%
Highest Quarterly Return, Label	rr_HighestQuarterlyReturnLabel	Best Quarter:
Highest Quarterly Return, Date	rr_BarChartHighestQuarterlyReturnDate	Jun. 30, 2009
Highest Quarterly Return	rr_BarChartHighestQuarterlyReturn	22.50%
Lowest Quarterly Return, Label	rr_LowestQuarterlyReturnLabel	Worst Quarter:
Lowest Quarterly Return, Date	rr_BarChartLowestQuarterlyReturnDate	Sep. 30, 2008
Lowest Quarterly Return	rr_BarChartLowestQuarterlyReturn	(20.70%)
INTECH International Fund | Class A, C, S, I, T Shares | Class T
Risk/Return:	rr_RiskReturnAbstract
Shareholder Fees Column [Text]	rr_ShareholderFeesColumnName	Class T
Maximum Sales Charge (load) Imposed on Purchases (as a percentage of offering price)	rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice	none
Maximum Deferred Sales Charge (load) (as a percentage of the lower of original purchase price or redemption proceeds)	rr_MaximumDeferredSalesChargeOverOther	none
Operating Expenses Column [Text]	rr_OperatingExpensesColumnName	Class T
Management Fees	rr_ManagementFeesOverAssets	0.55%
Distribution/Service (12b-1) Fees	rr_DistributionAndService12b1FeesOverAssets	none
Other Expenses	rr_OtherExpensesOverAssets	0.62%
Total Annual Fund Operating Expenses	rr_ExpensesOverAssets	1.17%	[1]
Fee Waiver	rr_FeeWaiverOrReimbursementOverAssets	none	[1]
Total Annual Fund Operating Expenses After Fee Waiver	rr_NetExpensesOverAssets	1.17%	[1]
Expense Example, By Year, Column [Text]	rr_ExpenseExampleByYearColumnName	Class T Shares
1 Year	rr_ExpenseExampleYear01	119
3 Years	rr_ExpenseExampleYear03	372
5 Years	rr_ExpenseExampleYear05	644
10 Years	rr_ExpenseExampleYear10	1,420
Expense Example, No Redemption, By Year, Column [Text]	rr_ExpenseExampleNoRedemptionByYearColumnName	Class T Shares
1 Year	rr_ExpenseExampleNoRedemptionYear01	119
3 Years	rr_ExpenseExampleNoRedemptionYear03	372
5 Years	rr_ExpenseExampleNoRedemptionYear05	644
10 Years	rr_ExpenseExampleNoRedemptionYear10	$ 1,420
INTECH International Fund | Class A, C, S, I, T Shares | Return Before Taxes | Class A
Risk/Return:	rr_RiskReturnAbstract
Column	rr_AverageAnnualReturnColumnName	Class A Shares
Label	rr_AverageAnnualReturnLabel	Return Before Taxes	[2]
1 Year	rr_AverageAnnualReturnYear01	10.06%
5 Years	rr_AverageAnnualReturnYear05	(5.23%)
Since Inception of Predecessor Fund	rr_AverageAnnualReturnSinceInception	(3.95%)
Inception Date	rr_AverageAnnualReturnInceptionDate	May 02, 2007
INTECH International Fund | Class A, C, S, I, T Shares | Return Before Taxes | Class C
Risk/Return:	rr_RiskReturnAbstract
Column	rr_AverageAnnualReturnColumnName	Class C Shares
Label	rr_AverageAnnualReturnLabel	Return Before Taxes	[3]
1 Year	rr_AverageAnnualReturnYear01	15.43%
5 Years	rr_AverageAnnualReturnYear05	(4.31%)
Since Inception of Predecessor Fund	rr_AverageAnnualReturnSinceInception	(3.22%)
Inception Date	rr_AverageAnnualReturnInceptionDate	May 02, 2007
INTECH International Fund | Class A, C, S, I, T Shares | Return Before Taxes | Class S
Risk/Return:	rr_RiskReturnAbstract
Column	rr_AverageAnnualReturnColumnName	Class S Shares
Label	rr_AverageAnnualReturnLabel	Return Before Taxes
1 Year	rr_AverageAnnualReturnYear01	16.48%
5 Years	rr_AverageAnnualReturnYear05	(4.18%)
Since Inception of Predecessor Fund	rr_AverageAnnualReturnSinceInception	(3.04%)
Inception Date	rr_AverageAnnualReturnInceptionDate	May 02, 2007
INTECH International Fund | Class A, C, S, I, T Shares | Return Before Taxes | Class I
Risk/Return:	rr_RiskReturnAbstract
Column	rr_AverageAnnualReturnColumnName	Class I Shares
Label	rr_AverageAnnualReturnLabel	Return Before Taxes
1 Year	rr_AverageAnnualReturnYear01	17.03%
5 Years	rr_AverageAnnualReturnYear05	(4.06%)
Since Inception of Predecessor Fund	rr_AverageAnnualReturnSinceInception	(2.88%)
Inception Date	rr_AverageAnnualReturnInceptionDate	May 02, 2007
INTECH International Fund | Class A, C, S, I, T Shares | Return Before Taxes | Class T
Risk/Return:	rr_RiskReturnAbstract
Column	rr_AverageAnnualReturnColumnName	Class T Shares
Label	rr_AverageAnnualReturnLabel	Return Before Taxes
1 Year	rr_AverageAnnualReturnYear01	16.70%
5 Years	rr_AverageAnnualReturnYear05	(5.11%)
Since Inception of Predecessor Fund	rr_AverageAnnualReturnSinceInception	(4.20%)
Inception Date	rr_AverageAnnualReturnInceptionDate	May 02, 2007
INTECH International Fund | Class A, C, S, I, T Shares | Return After Taxes on Distributions | Class I
Risk/Return:	rr_RiskReturnAbstract
Column	rr_AverageAnnualReturnColumnName	Class I Shares
Label	rr_AverageAnnualReturnLabel	Return After Taxes on Distributions
1 Year	rr_AverageAnnualReturnYear01	16.65%
5 Years	rr_AverageAnnualReturnYear05	(4.20%)
Since Inception of Predecessor Fund	rr_AverageAnnualReturnSinceInception	(3.06%)
Inception Date	rr_AverageAnnualReturnInceptionDate	May 02, 2007
INTECH International Fund | Class A, C, S, I, T Shares | Return After Taxes on Distributions and Sale of Fund Shares | Class I
Risk/Return:	rr_RiskReturnAbstract
Column	rr_AverageAnnualReturnColumnName	Class I Shares
Label	rr_AverageAnnualReturnLabel	Return After Taxes on Distributions and Sale of Fund Shares	[4]
1 Year	rr_AverageAnnualReturnYear01	11.76%
5 Years	rr_AverageAnnualReturnYear05	(3.29%)
Since Inception of Predecessor Fund	rr_AverageAnnualReturnSinceInception	(2.32%)
Inception Date	rr_AverageAnnualReturnInceptionDate	May 02, 2007
INTECH International Fund | Class A, C, S, I, T Shares | Morgan Stanley Capital International EAFE® Index (net of foreign withholding taxes) (reflects no deduction for expenses, fees, or taxes, except foreign withholding taxes)
Risk/Return:	rr_RiskReturnAbstract
Label	rr_AverageAnnualReturnLabel	Morgan Stanley Capital International EAFE® Index (net of foreign withholding taxes)
1 Year	rr_AverageAnnualReturnYear01	17.32%
5 Years	rr_AverageAnnualReturnYear05	(3.69%)
Since Inception of Predecessor Fund	rr_AverageAnnualReturnSinceInception	(2.89%)
Inception Date	rr_AverageAnnualReturnInceptionDate	May 02, 2007

[1] Janus Capital has contractually agreed to waive its investment advisory fee and/or reimburse Fund expenses to the extent that the Fund’s total annual fund operating expenses (excluding the distribution and shareholder servicing fees – applicable to Class A Shares, Class C Shares, and Class S Shares; administrative services fees payable pursuant to the Transfer Agency Agreement; brokerage commissions; interest; dividends; taxes; acquired fund fees and expenses; and extraordinary expenses) exceed 1.00% until at least November 1, 2014. The contractual waiver may be terminated or modified prior to this date only at the discretion of the Board of Trustees.

[2] Calculated assuming maximum permitted sales loads.

[3] The one year return is calculated to include the contingent deferred sales charge.

[4] If the Fund incurs a loss, which generates a tax benefit, the Return After Taxes on Distributions and Sale of Fund Shares may exceed the Fund’s other return figures.

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Janus Global Allocation Fund - Conservative | Class A, C, S, I, T Shares

FUND SUMMARY

Janus Global Allocation Fund – Conservative
(formerly named Janus Conservative Allocation Fund)

INVESTMENT OBJECTIVE

Janus Global Allocation Fund – Conservative seeks total return through a primary emphasis on income with a secondary emphasis on growth of capital.

FEES AND EXPENSES OF THE FUND

This table describes the fees and expenses that you may pay if you buy and hold Shares of the Fund. Each share class has different expenses, but represents an investment in the same Fund.

For Class A Shares, you may qualify for sales charge discounts if you and your family invest, or agree to invest in the future, at least $50,000 in the Fund or in other Janus mutual funds. More information about these and other discounts, as well as eligibility requirements for each share class, is available from your financial professional and in the “Purchases” section on page 52 of the Fund’s Prospectus and in the “Purchases” section on page 57 of the Fund’s Statement of Additional Information.

SHAREHOLDER FEES
(fees paid directly from your investment)

Shareholder Fees Janus Global Allocation Fund - Conservative Class A, C, S, I, T Shares	Class A	Class C	Class S	Class I	Class T
Shareholder Fees Column [Text]	Class A	Class C	Class S	Class I	Class T
Maximum Sales Charge (load) Imposed on Purchases (as a percentage of offering price)	5.75%	none	none	none	none
Maximum Deferred Sales Charge (load) (as a percentage of the lower of original purchase price or redemption proceeds)	none	1.00%	none	none	none

ANNUAL FUND OPERATING EXPENSES
(expenses that you pay each year as a percentage of the value of your investment)

Annual Fund Operating Expenses Janus Global Allocation Fund - Conservative Class A, C, S, I, T Shares	Class A	Class C	Class S	Class I	Class T
Operating Expenses Column [Text]	Class A	Class C	Class S	Class I	Class T
Management Fees	0.05%	0.05%	0.05%	0.05%	0.05%
Distribution/Service (12b-1) Fees	0.25%	1.00%	0.25%	none	none
Other Expenses	0.13%	0.14%	0.31%	0.15%	0.31%
Acquired Fund Fees and Expenses	0.60%	0.60%	0.60%	0.60%	0.60%
Total Annual Fund Operating Expenses	1.03%	1.79%	1.21%	0.80%	0.96%

EXAMPLE:

The Example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds.

The Example assumes that you invest $10,000 in the Fund for the time periods indicated and reinvest all dividends and distributions. The Example also assumes that your investment has a 5% return each year and that the Fund’s operating expenses (including the operating expenses of the underlying funds) remain the same. Although your actual costs may be higher or lower, based on these assumptions your costs would be:

If Shares are redeemed:

Expense Example Janus Global Allocation Fund - Conservative Class A, C, S, I, T Shares (USD $)	Expense Example, By Year, Column [Text]	1 Year	3 Years	5 Years	10 Years
Class A	Class A Shares	674	884	1,111	1,762
Class C	Class C Shares	282	563	970	2,105
Class S	Class S Shares	123	384	665	1,466
Class I	Class I Shares	82	255	444	990
Class T	Class T Shares	98	306	531	1,178

If Shares are not redeemed:

Expense Example, No Redemption Janus Global Allocation Fund - Conservative Class A, C, S, I, T Shares (USD $)	Expense Example, No Redemption, By Year, Column [Text]	1 Year	3 Years	5 Years	10 Years
Class A	Class A Shares	674	884	1,111	1,762
Class C	Class C Shares	182	563	970	2,105
Class S	Class S Shares	123	384	665	1,466
Class I	Class I Shares	82	255	444	990
Class T	Class T Shares	98	306	531	1,178

Portfolio Turnover: 

The Fund pays transaction costs, such as commissions, when it buys and sells securities (or “turns over” its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when Fund shares are held in a taxable account. These costs, which are not reflected in annual fund operating expenses or in the Example, affect the Fund’s performance. During the most recent fiscal year, the Fund’s portfolio turnover rate was 69% of the average value of its portfolio.

PRINCIPAL INVESTMENT STRATEGIES

The Fund seeks to achieve its investment objective by investing in other Janus mutual funds (“underlying funds”) that represent a variety of asset classes and investment styles and provide exposure to issuers that are economically tied to countries throughout the world. Through its investments in underlying funds, the Fund invests in issuers from several different countries and may, under unusual circumstances, be invested in a single country. As a result, the Fund normally will have approximately 40% of its net assets allocated to non-U.S. investments. The Fund may also have significant exposure to emerging markets.

The Fund pursues this objective by investing in a diversified portfolio of underlying funds, resulting in an allocation of the Fund’s investments that normally provides exposure of approximately 55% to fixed-income securities and money market instruments, 40% to equity investments, and 5% to alternative investments. The target allocation and the allocation of the Fund’s assets among underlying funds are based on quantitative and qualitative analysis. Because it invests in other funds, the Fund is considered a “fund of funds.”

The Fund’s asset allocation is intended to diversify investments throughout the world among equity investments, fixed-income securities, cash equivalents, and alternative investments. The portfolio manager determines the overall composition of the Fund, oversees the investment process, and is responsible for the day-to-day management of the Fund. The portfolio manager continually monitors asset class allocations and periodically rebalances the Fund’s investments in the underlying funds. The portfolio manager also regularly reviews the allocation of Fund assets in the underlying funds and may modify the underlying funds’ weightings or substitute other underlying funds to emphasize and mitigate risk exposures that may arise as a result of the implementation of the allocations. An independent asset allocation service provides evaluations of asset allocations that the portfolio manager may use in implementing the allocations among the underlying funds.

Additionally, the portfolio manager consults with a committee (the “Janus Global Allocation Committee”) to regularly review the broad market, macroeconomic conditions and other global financial factors that may impact the Fund’s allocation of assets among the underlying funds and asset classes. The Janus Global Allocation Committee is comprised of investment professionals of Janus Capital and may also include investment professionals of Janus Capital’s affiliated investment advisers. The portfolio manager and Janus Global Allocation Committee normally meet on a quarterly basis. The portfolio manager may change the Fund’s asset class allocations, the underlying funds, an underlying fund’s asset category, or weightings among asset classes or underlying funds without prior shareholder notice.

The Fund will normally allocate approximately 55% of its investments to underlying bond funds and money market instruments, approximately 40% of its investments to underlying funds that provide varying exposure to common stocks of large U.S.-based companies, small- to mid-capitalization companies, and international companies (including those with exposure to emerging markets), and approximately 5% of its investments to underlying funds that seek returns uncorrelated with the returns of stocks and bonds by providing exposure to alternative investments and alternative investment strategies. Refer to Appendix A in this Prospectus for a brief description of the investment strategies of each of the currently available underlying funds.

When market conditions dictate a more defensive strategy, the Fund or an underlying fund may temporarily hold cash or invest its assets in temporary investments. In that case, the Fund may take positions that are inconsistent with its investment objective. As a result, the Fund may not achieve its investment objective.

PRINCIPAL INVESTMENT RISKS

The biggest risk is that the Fund’s returns will vary, and you could lose money. The Fund is designed for long-term investors seeking income and, to a lesser extent, growth of capital. Investments in a portfolio with common stock and alternative investment exposure tend to be more volatile than many other investment choices.

Main Risks Associated with the Fund
Allocation Risk. The Fund’s ability to achieve its investment objective depends largely upon the portfolio manager’s allocation of assets among the underlying funds and other securities, using the optimization process (a process that utilizes quantitative analysis of a number of factors, such as historical risk, performance, fund classifications, and the relationship among underlying funds) and the judgment of the portfolio manager. You could lose money on your investment in the Fund as a result of these allocations. The Fund will typically invest in a number of different underlying funds; however, to the extent that the Fund invests a significant portion of its assets in a single underlying fund, it will be more sensitive to the risks associated with that fund and any investments in which that fund focuses.

Affiliated Fund Risk. Janus Capital has the authority to select and substitute underlying affiliated mutual funds. The fees paid to Janus Capital by some Janus mutual funds are generally higher than the fees paid to Janus Capital by the Fund or by other funds and share classes available for investment by the Fund. These conditions may create a conflict of interest when selecting underlying affiliated mutual funds and share classes for investment. Janus Capital, however, is a fiduciary to the Fund and its shareholders and is legally obligated to act in their best interest when selecting underlying affiliated mutual funds.

Main Risks Associated with the Underlying Funds and Securities
The biggest risk is that the underlying funds’ returns will vary, and you could lose money.

Fixed-Income Securities Risk. Approximately 55% of the Fund’s assets are allocated to fixed-income securities through investments in underlying funds. Typically, the values of fixed-income securities change inversely with prevailing interest rates. Therefore, a fundamental risk of fixed-income securities is interest rate risk, which is the risk that the value of such securities will generally decline as prevailing interest rates rise, which may cause an underlying fund’s net asset value to likewise decrease. How specific fixed-income securities may react to changes in interest rates will depend on the specific characteristics of each security. Fixed-income securities are also subject to credit risk, prepayment risk, valuation risk, and liquidity risk. Credit risk is the risk that the credit strength of an issuer of a fixed-income security will weaken and/or that the issuer will be unable to make timely principal and interest payments and that the security may go into default. Prepayment risk is the risk that during periods of falling interest rates, certain fixed-income securities with higher interest rates, such as mortgage- and asset-backed securities, may be prepaid by their issuers thereby reducing the amount of interest payments. Valuation risk is the risk that one or more of the fixed-income securities in which an underlying fund invests are priced differently than the value realized upon such security’s sale. In times of market instability, valuation may be more difficult. Liquidity risk is the risk that fixed-income securities may be difficult or impossible to sell at the time that an underlying fund’s portfolio manager would like or at the price the portfolio manager believes the security is currently worth.

Mortgage-Backed Securities Risk. Mortgage-backed securities are classified generally as either commercial mortgage-backed securities or residential mortgage-backed securities, each of which is subject to certain specific risks. Mortgage-backed securities tend to be more sensitive to changes in interest rates than other types of debt securities. Investments in mortgage-backed securities are subject to both extension risk, where borrowers extend the duration of their mortgages in times of rising interest rates, and prepayment risk, where borrowers pay off their mortgages sooner than expected in times of declining interest rates. These risks may reduce the Fund’s returns. In addition, investments in mortgage-backed securities, including those comprised of subprime mortgages, may be subject to a higher degree of credit risk, valuation risk, and liquidity risk than various other types of fixed-income securities.

Market Risk. Approximately 40% of the Fund’s assets are allocated to equity investments through investments in underlying funds. The value of an underlying fund’s portfolio may decrease if the value of an individual company or security, or multiple companies or securities, in the portfolio decreases or if a portfolio manager’s belief about a company’s intrinsic worth is incorrect. Further, regardless of how well individual companies or securities perform, the value of an underlying fund’s portfolio could also decrease if there are deteriorating economic or market conditions. It is important to understand that the value of your investment may fall, sometimes sharply, in response to changes in the market, and you could lose money.

Foreign Exposure Risk. Certain underlying funds may have significant exposure to foreign markets as a result of their investments in foreign securities, including investments in emerging markets, which can be more volatile than the U.S. markets. As a result, an underlying fund’s returns and net asset value may be affected to a large degree by fluctuations in currency exchange rates or political or economic conditions in a particular country. A market swing in one or more countries or regions where an underlying fund has invested a significant amount of its assets may have a greater effect on an underlying fund’s performance than it would in a more geographically diversified portfolio. An underlying fund’s investments in emerging market countries may involve risks greater than, or in addition to, the risks of investing in more developed countries.

Emerging Markets Risk. The risks of foreign investing mentioned above are heightened when investing in emerging markets. Emerging markets securities involve a number of additional risks, which may result from less government supervision and regulation of business and industry practices (including the potential lack of strict finance and accounting controls and standards), stock exchanges, brokers, and listed companies, making these investments potentially more volatile in price and less liquid than investments in developed securities markets, resulting in greater risk to investors. In addition, an underlying fund’s investments may be denominated in foreign currencies and therefore, changes in the value of a country’s currency compared to the U.S. dollar may affect the value of an underlying fund’s investments. To the extent that an underlying fund invests a significant portion of its assets in the securities of issuers in or companies of a single country or region, it is more likely to be impacted by events or conditions affecting that country or region, which could have a negative impact on the Fund’s performance. Some of the risks of investing directly in foreign and emerging market securities may be reduced when an underlying fund invests indirectly in foreign securities through various other investment vehicles including derivatives, which also involve other risks.

Sovereign Debt Risk. An underlying fund may invest in U.S. and foreign government debt securities (“sovereign debt”). Investments in U.S. sovereign debt are considered low risk. However, investments in non-U.S. sovereign debt can involve a high degree of risk, including the risk that the governmental entity that controls the repayment of sovereign debt may not be willing or able to repay the principal and/or to pay the interest on its sovereign debt in a timely manner. A sovereign debtor’s willingness or ability to satisfy its debt obligation may be affected by various factors including, but not limited to, its cash flow situation, the extent of its foreign currency reserves, the availability of foreign exchange when a payment is due, and the relative size of its debt position in relation to its economy as a whole. In the event of default, there may be limited or no legal remedies for collecting sovereign debt and there may be no bankruptcy proceedings through which the underlying fund may collect all or part of the sovereign debt that a governmental entity has not repaid.

Alternative Investments Allocation Risk. Approximately 5% of the Fund’s assets are allocated to alternative investments through investments in underlying funds that invest in alternative investment strategies. In connection with the Fund’s allocation to alternative investments, the Fund may invest in a Janus underlying fund, Janus Diversified Alternatives Fund, which seeks returns uncorrelated with the returns generated by investments in stocks and bonds. In addition, as part of its alternative investments allocation, the Fund may invest in Janus Global Real Estate Fund. Janus Diversified Alternatives Fund’s ability to achieve its investment objective depends largely upon the successful evaluation of the risk, potential returns, and correlation properties with respect to its investments. There is a risk that the returns provided by alternative investments may be subject to high volatility and that an underlying fund’s portfolio manager’s beliefs about the expected returns, risk and correlation properties of one or more of an underlying fund’s investments may be incorrect. There is also a risk that an underlying fund’s investments will correlate with the performance of stocks and bonds to a greater degree than anticipated. Janus Capital does not have prior experience managing the investment strategy of Janus Diversified Alternatives Fund, and there is no guarantee that the investment techniques and analysis used by the underlying fund’s portfolio managers will produce the desired results. All of these factors may negatively affect your investment in the Fund and you could lose money. Investment in the underlying funds also involves derivatives, counterparty, leverage, real estate-related, and commodity-linked investment risks.

Counterparty Risk. Certain derivative and “over-the-counter” instruments, such as swaps and forwards, are subject to the risk that the other party to a contract will not fulfill its contractual obligations.

Commodity-Linked Investments Risk. Certain underlying funds may invest in derivatives that have exposure to the commodities markets. Such exposure may subject an underlying fund to greater volatility than investments in traditional securities. The value of a commodity-linked derivative investment typically is based upon the price movements of a physical commodity (such as heating oil, livestock, or agricultural products), a commodity futures contract or commodity index, or some other readily measurable economic variable. The value of commodity-linked derivative instruments may therefore be affected by changes in overall market movements, volatility of the underlying benchmark, changes in interest rates, or other factors affecting a particular industry or commodity such as drought, floods, weather, livestock disease, embargoes, tariffs, and international economic, political, and regulatory developments.

Derivatives Risk. Certain underlying funds may invest in derivatives. Derivatives can be highly volatile and involve risks in addition to the risks of the underlying referenced securities. Gains or losses from a derivative investment can be substantially greater than the derivative’s original cost, and can therefore involve leverage. Leverage may cause an underlying fund to be more volatile than if it had not used leverage. Derivatives can be less liquid than other types of investments and entail the risk that the counterparty will default on its payment obligations.

Exchange-Traded Funds Risk. Certain underlying funds may purchase shares of exchange-traded funds (“ETFs”) to gain exposure to a particular portion of the market. ETFs are pooled investment vehicles, which may be managed or unmanaged, that generally seek to track the performance of a specific index. ETFs are traded on an exchange at market prices that may vary from the net asset value of their underlying investments. When an underlying fund invests in an ETF, in addition to directly bearing the expenses associated with its own operations, it will bear a pro rata portion of the ETF’s expenses. ETFs have certain inherent risks generally associated with investments in a portfolio of securities in which the ETF is invested, including the risk that the general level of stock prices may decline, thereby adversely affecting the value of each unit of the ETF. ETFs also involve the risk that an active trading market for an ETF’s shares may not develop or be maintained.

Exchange-Traded Notes Risk. Certain underlying funds may invest in exchange-traded notes (“ETNs”), which are debt securities whose returns are linked to a particular index. ETNs are typically linked to the performance of a commodities index that reflects the potential return on unleveraged investments in futures contracts of physical commodities, plus a specified rate of interest that could be earned on cash collateral. ETNs are subject to credit risk and counterparty risk. The value of an ETN may vary and may be influenced by time to maturity, level of supply and demand for the ETN, volatility and lack of liquidity in underlying commodities markets, changes in the applicable interest rates, changes in the issuer’s credit rating, and economic, legal, political, or geographic events that affect the referenced commodity. When an underlying fund invests in ETNs it will bear its proportionate share of any fees and expenses borne by the ETN. There may be restrictions on an underlying fund’s right to redeem its investment in an ETN, which is meant to be held until maturity. An underlying fund’s decision to sell its ETN holdings may be limited by the availability of a secondary market.

An investment in the Fund is not a bank deposit and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency.

PERFORMANCE INFORMATION

The following information provides some indication of the risks of investing in the Fund by showing how the Fund’s performance has varied over time. Class T Shares (formerly named Class J Shares, the initial share class) of the Fund commenced operations with the Fund’s inception. Class A Shares, Class C Shares, Class S Shares, and Class I Shares of the Fund commenced operations on July 6, 2009.

• The performance shown for Class T Shares is calculated using the fees and expenses of Class T Shares in effect during the periods shown, net of any applicable fee and expense limitations or waivers.
• The performance shown for Class A Shares, Class C Shares, Class S Shares, and Class I Shares for periods prior to July 6, 2009, reflects the performance of the Fund’s former Class J Shares, calculated using the fees and expenses of each respective share class, without the effect of any fee and expense limitations or waivers.

If Class A Shares, Class C Shares, Class S Shares, and Class I Shares of the Fund had been available during periods prior to July 6, 2009, the performance shown for each respective share class may have been different. The performance shown for periods following the Fund’s commencement of Class A Shares, Class C Shares, Class S Shares, and Class I Shares reflects the fees and expenses of each respective share class, net of any applicable fee and expense limitations or waivers.

The bar chart depicts the change in performance from year to year during the periods indicated. Performance information for each underlying fund is available in its prospectus and/or the most recent annual or semiannual report. The bar chart figures do not include any applicable sales charges that an investor may pay when they buy or sell Class A Shares or Class C Shares of the Fund. If sales charges were included, the returns would be lower. The table compares the Fund’s average annual returns for the periods indicated to broad-based securities market indices. The indices are not actively managed and are not available for direct investment. All figures assume reinvestment of dividends and distributions. For certain periods, the Fund’s performance reflects the effect of expense waivers. Without the effect of these expense waivers, the performance shown would have been lower.

The Fund’s past performance (before and after taxes) does not necessarily indicate how it will perform in the future. Updated performance information is available at janus.com/advisor/mutual-funds or by calling 1-877-335-2687.

Annual Total Returns for Class T Shares (calendar year-end)

Best Quarter:  Second Quarter 2009  10.64%          Worst Quarter:  Third Quarter 2008  −6.58%

The Fund’s year-to-date return as of the calendar quarter ended September 30, 2013 was 6.61%.

Average Annual Total Returns (periods ended 12/31/12)

Average Annual Total Returns Janus Global Allocation Fund - Conservative Class A, C, S, I, T Shares	Column	Label		1 Year	5 Years	Since Inception	Inception Date
Class T Return Before Taxes	Class T Shares	Return Before Taxes		10.82%	5.19%	6.71%	Dec. 30, 2005
Class T Return After Taxes on Distributions	Class T Shares	Return After Taxes on Distributions		9.91%	4.14%	5.69%	Dec. 30, 2005
Class T Return After Taxes on Distributions and Sale of Fund Shares	Class T Shares	Return After Taxes on Distributions and Sale of Fund Shares		7.17%	3.85%	5.23%	Dec. 30, 2005
Class A Return Before Taxes	Class A Shares	Return Before Taxes	[1]	4.20%	3.81%	5.63%	Dec. 30, 2005
Class C Return Before Taxes	Class C Shares	Return Before Taxes	[2]	8.70%	4.28%	5.75%	Dec. 30, 2005
Class S Return Before Taxes	Class S Shares	Return Before Taxes		10.42%	4.78%	6.27%	Dec. 30, 2005
Class I Return Before Taxes	Class I Shares	Return Before Taxes		10.92%	5.19%	6.71%	Dec. 30, 2005
Barclays Global Aggregate Bond Index (reflects no deduction for expenses, fees, or taxes)		Barclays Global Aggregate Bond Index		4.32%	5.44%	6.18%	Dec. 30, 2005
Global Conservative Allocation Index (reflects no deduction for expenses, fees, or taxes, except any applicable foreign withholding taxes)		Global Conservative Allocation Index		9.09%	3.22%	5.48%	Dec. 30, 2005
S&P 500® Index (reflects no deduction for expenses, fees, or taxes)		S&P 500® Index		16.00%	1.66%	4.12%	Dec. 30, 2005
Conservative Allocation Index (reflects no deduction for expenses, fees, or taxes, except any applicable foreign withholding taxes)		Conservative Allocation Index		9.21%	4.26%	5.49%	Dec. 30, 2005

Effective February 15, 2013, the Fund’s primary benchmark index changed from the S&P 500^® Index to the Barclays Global Aggregate Bond Index to reflect the global investment strategies of the Fund. Additionally, the Fund changed the name of its secondary benchmark index from Conservative Allocation Index to Global Conservative Allocation Index and its composition from an internally-calculated, hypothetical combination of unmanaged indices that combines total returns from the Barclays U.S. Aggregate Bond Index (60%), the Dow Jones Wilshire 5000 Index (28%), and the Morgan Stanley Capital International Europe, Australasia, Far East Index (“MSCI EAFE^®”) Index (12%) to an internally-calculated, hypothetical combination of unmanaged indices that combines total returns from the Barclays Global Aggregate Bond Index (60%) and the Morgan Stanley Capital International All Country World Index^SM (40%). The Barclays Global Aggregate Bond Index is an index that provides a broad-based measure of the global investment grade fixed-rate debt markets. Janus Capital believes that the foregoing benchmark index changes provide a more appropriate representation of the Fund’s revised investment strategy that includes an increased focus on global investments, including emerging markets.

After-tax returns are calculated using distributions for the Fund’s Class T Shares (formerly named Class J Shares, the initial share class). After-tax returns are calculated using the historically highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes. Actual after-tax returns depend on your individual tax situation and may differ from those shown in the preceding table. The after-tax return information shown above does not apply to Fund shares held through a tax-deferred account, such as a 401(k) plan or an IRA.

After-tax returns are only shown for Class T Shares of the Fund. After-tax returns for the other classes of Shares will vary from those shown for Class T Shares due to varying sales charges (as applicable), fees, and expenses among the classes.

[1] Calculated assuming maximum permitted sales loads.

[2] The one year return is calculated to include the contingent deferred sales charge.

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Perkins Large Cap Value Fund | Class D Shares

FUND SUMMARY

Perkins Large Cap Value Fund

INVESTMENT OBJECTIVE

Perkins Large Cap Value Fund seeks capital appreciation.

FEES AND EXPENSES OF THE FUND

This table describes the fees and expenses that you may pay if you buy and hold Shares of the Fund.

ANNUAL FUND OPERATING EXPENSES
(expenses that you pay each year as a percentage of the value of your investment)

Annual Fund Operating Expenses		Perkins Large Cap Value Fund Class D Shares Class D
Operating Expenses Column [Text]		Class D
Management Fees (may adjust up or down)		0.52%
Other Expenses		0.32%
Total Annual Fund Operating Expenses	[1]	0.84%
Fee Waiver	[1]	0.08%
Total Annual Fund Operating Expenses After Fee Waiver	[1]	0.76%

EXAMPLE:

The following Example is based on expenses without waivers. The Example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds.

The Example assumes that you invest $10,000 in the Fund for the time periods indicated, reinvest all dividends and distributions, and then redeem all of your Shares at the end of each period. The Example also assumes that your investment has a 5% return each year and that the Fund’s operating expenses without waivers remain the same. Although your actual costs may be higher or lower, based on these assumptions your costs would be:

Expense Example (USD $)	Expense Example, By Year, Column [Text]	1 Year	3 Years	5 Years	10 Years
Perkins Large Cap Value Fund Class D Shares Class D	Class D Shares	86	268	466	1,037

Portfolio Turnover:

The Fund pays transaction costs, such as commissions, when it buys and sells securities (or “turns over” its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when Fund shares are held in a taxable account. These costs, which are not reflected in annual fund operating expenses or in the Example, affect the Fund’s performance. During the most recent fiscal year, the Fund’s portfolio turnover rate was 45% of the average value of its portfolio.

PRINCIPAL INVESTMENT STRATEGIES

The Fund pursues its investment objective by investing primarily in common stocks selected for their capital appreciation potential. The Fund primarily invests in the common stocks of large-sized companies whose stock prices the portfolio managers believe to be undervalued. The Fund invests, under normal circumstances, at least 80% of its net assets in equity securities of companies having, at the time of purchase, market capitalizations equal to or greater than the median market capitalization of companies included in the Russell 1000^® Value Index. The market capitalizations within the index will vary, but as of June 30, 2013, they ranged from approximately $487 million to $422.5 billion, and the median market capitalization was $5.9 billion. The Fund may also invest in foreign equity and debt securities, which may include investments in emerging markets. The Fund may invest, under normal circumstances, up to 20% of its net assets in securities of companies having market capitalizations outside of the aforementioned market capitalization ranges. In addition, when the portfolio managers believe that market conditions are unfavorable for investing, or when they are otherwise unable to locate attractive investment opportunities, the Fund may invest up to 20% of its net assets in exchange-traded funds (“ETFs”), including commodity-related ETFs, cash, or similar investments.

The Fund focuses on companies that have fallen out of favor with the market or that appear to be temporarily misunderstood by the investment community. The Fund’s portfolio managers generally look for companies with:

• strong balance sheets and solid recurring free cash flows
• attractive relative and absolute valuation ratios or that have underperformed recently
• favorable reward to risk characteristics

The Fund may invest its assets in derivatives, which are instruments that have a value derived from, or directly linked to, an underlying asset, such as equity securities, fixed-income securities, commodities, currencies, interest rates, or market indices, as substitutes for securities in which the Fund invests. The Fund may invest in derivative instruments (by taking long and/or short positions) for different purposes, including hedging (to offset risks associated with an investment, currency exposure, or market conditions) and to earn income and enhance returns.

PRINCIPAL INVESTMENT RISKS

The biggest risk is that the Fund’s returns will vary, and you could lose money. The Fund is designed for long-term investors seeking an equity portfolio, including common stocks. Common stocks tend to be more volatile than many other investment choices.

Value Investing Risk. Because different types of stocks tend to shift in and out of favor depending on market and economic conditions, “value” stocks may perform differently than other types of stocks and from the market as a whole, and can continue to be undervalued by the market for long periods of time. It is also possible that a value stock will never appreciate to the extent expected by the portfolio managers. When the Fund’s investments in cash or similar investments increase due to a lack of favorable investment opportunities or other extraordinary factors, the Fund may not participate in market advances or declines to the same extent that it would if the Fund had been fully invested.

Market Risk. The value of the Fund’s portfolio may decrease if the value of an individual company or security, or multiple companies or securities, in the portfolio decreases or if the portfolio managers’ belief about a company’s intrinsic worth is incorrect. Further, regardless of how well individual companies or securities perform, the value of the Fund’s portfolio could also decrease if there are deteriorating economic or market conditions. It is important to understand that the value of your investment may fall, sometimes sharply, in response to changes in the market, and you could lose money.

Foreign Exposure Risk. The Fund may have exposure to foreign markets as a result of its investments in foreign securities, including investments in emerging markets, which can be more volatile than the U.S. markets. As a result, its returns and net asset value may be affected to a large degree by fluctuations in currency exchange rates or political or economic conditions in a particular country. In some foreign markets, there may not be protection against failure by other parties to complete transactions. It may not be possible for the Fund to repatriate capital, dividends, interest, and other income from a particular country or governmental entity. In addition, a market swing in one or more countries or regions where the Fund has invested a significant amount of its assets may have a greater effect on the Fund’s performance than it would in a more geographically diversified portfolio. To the extent the Fund invests in foreign debt securities, such investments are sensitive to changes in interest rates. Additionally, investments in securities of foreign governments involve the risk that a foreign government may not be willing or able to pay interest or repay principal when due.

Eurozone Risk. A number of countries in the European Union (“EU”) have experienced severe economic and financial difficulties. As a result, financial markets in the EU have been subject to extreme volatility and declines in asset values and liquidity. Responses to these financial problems by European governments, central banks, and others, including austerity measures and reforms, may not work, may result in social unrest, and may limit future growth and economic recovery or have other unintended consequences. Further defaults or restructurings by governments and others of their debt could have additional adverse effects on economies, financial markets, and asset valuations around the world. To the extent that the Fund has exposure to European markets or to transactions tied to the value of the euro, these events could negatively affect the value and liquidity of the Fund’s investments.

Exchange-Traded Funds Risk. The Fund may invest in ETFs, which are typically open-end investment companies that are traded on a national securities exchange. ETFs typically incur fees, such as investment advisory fees and other operating expenses that are separate from those of the Fund, which will be indirectly paid by the Fund. As a result, the cost of investing in the Fund may be higher than the cost of investing directly in ETFs and may be higher than other mutual funds that invest directly in stocks and bonds. Further, the price movement of an ETF may fluctuate against the underlying securities or commodities it tracks and may result in a loss. Because the value of ETF shares depends on the demand in the market, the Fund may not be able to purchase or sell an ETF at the most optimal time, which could adversely affect the Fund’s performance.

The ETFs in which the Fund invests are subject to specific risks, depending on the investment strategy of the ETF. In turn, the Fund will be subject to substantially the same risks as those associated with direct exposure to the securities or commodities held by the ETF. Because the Fund may invest in a broad range of ETFs, such risks may include, but are not limited to, leverage risk, foreign exposure risk, and commodities risk.

Derivatives Risk. Derivatives can be highly volatile and involve risks in addition to the risks of the underlying referenced securities. Gains or losses from a derivative investment can be substantially greater than the derivative’s original cost, and can therefore involve leverage. Leverage may cause the Fund to be more volatile than if it had not used leverage. Derivatives can be less liquid than other types of investments and entail the risk that the counterparty will default on its payment obligations.

An investment in the Fund is not a bank deposit and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency.

PERFORMANCE INFORMATION

The following information provides some indication of the risks of investing in the Fund by showing how the Fund’s performance has varied over time. Class D Shares of the Fund commenced operations on February 16, 2010. The performance shown for Class D Shares for the period July 6, 2009 to February 16, 2010, reflects the performance of the Fund’s Class I Shares, calculated using the fees and expenses of Class D Shares, without the effect of any fee and expense limitations or waivers. Performance shown for the period prior to July 6, 2009, reflects the historical performance of the Janus Adviser Perkins Large Cap Value Fund’s (“JAD predecessor fund”) Class I Shares prior to the reorganization of Class I Shares of the JAD predecessor fund into Class I Shares of the Fund, calculated using the fees and expenses of Class D Shares, without the effect of any fee and expense limitations or waivers. If Class D Shares of the Fund had been available during periods prior to February 16, 2010, the performance shown may have been different. The performance shown for periods following the Fund’s commencement of Class D Shares reflects the fees and expenses of Class D Shares, net of any applicable fee and expense limitations or waivers.

The bar chart depicts the change in performance from year to year during the periods indicated. The table compares the Fund’s average annual returns for the periods indicated to a broad-based securities market index. The index is not actively managed and is not available for direct investment. All figures assume reinvestment of dividends and distributions. For certain periods, the Fund’s performance reflects the effect of expense waivers. Without the effect of these expense waivers, the performance shown would have been lower.

The Fund’s past performance (before and after taxes) does not necessarily indicate how it will perform in the future. Updated performance information is available at janus.com/allfunds or by calling 1-800-525-3713.

Annual Total Returns for Class D Shares (calendar year-end)

Best Quarter:  Second Quarter 2009  15.02%          Worst Quarter:  Third Quarter 2011  −14.77%

The Fund’s year-to-date return as of the calendar quarter ended September 30, 2013 was 17.90%.

Average Annual Total Returns (periods ended 12/31/12)

Average Annual Total Returns Perkins Large Cap Value Fund Class D Shares	Column	Label	1 Year	Since Inception of Predecessor Fund	Inception Date
Class D Return Before Taxes	Class D Shares	Return Before Taxes	13.12%	11.75%	Dec. 31, 2008
Class D Return After Taxes on Distributions	Class D Shares	Return After Taxes on Distributions	12.56%	11.01%	Dec. 31, 2008
Class D Return After Taxes on Distributions and Sale of Fund Shares	Class D Shares	Return After Taxes on Distributions and Sale of Fund Shares	9.29%	10.00%	Dec. 31, 2008
Russell 1000® Value Index (reflects no deduction for expenses, fees, or taxes)		Russell 1000® Value Index	17.51%	13.01%	Dec. 31, 2008

The Russell 1000^® Value Index measures the performance of those Russell 1000^® companies with lower price-to-book ratios and lower forecasted growth values. This index is used to calculate the performance fee adjustment.

After-tax returns are calculated using distributions for the Fund’s Class D Shares for the periods following February 16, 2010; for the Fund’s Class I Shares for the period following July 6, 2009; and for the JAD predecessor fund’s Class I Shares for the period prior to July 6, 2009. If Class D Shares of the Fund had been available during these earlier periods, distributions may have been different and thus, after-tax returns may have been different from those shown. After-tax returns are calculated using the historically highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes. Actual after-tax returns depend on your individual tax situation and may differ from those shown in the preceding table. The after-tax return information shown above does not apply to Fund shares held through a tax-deferred account, such as a 401(k) plan or an IRA.

[1] Janus Capital has contractually agreed to waive its investment advisory fee and/or reimburse Fund expenses to the extent that the Fund’s total annual fund operating expenses (excluding any performance adjustments to management fees, administrative services fees payable pursuant to the Transfer Agency Agreement, brokerage commissions, interest, dividends, taxes, acquired fund fees and expenses, and extraordinary expenses) exceed 0.75% until at least November 1, 2014. The contractual waiver may be terminated or modified prior to this date only at the discretion of the Board of Trustees.

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Label	Element	Value
Risk/Return:	rr_RiskReturnAbstract
Registrant Name	dei_EntityRegistrantName	JANUS INVESTMENT FUND
Prospectus Date	rr_ProspectusDate	Oct. 28, 2013
Perkins Mid Cap Value Fund | Class L Shares
Risk/Return:	rr_RiskReturnAbstract
Risk/Return [Heading]	rr_RiskReturnHeading	FUND SUMMARY Perkins Mid Cap Value Fund
Objective [Heading]	rr_ObjectiveHeading	INVESTMENT OBJECTIVE
Objective, Primary [Text Block]	rr_ObjectivePrimaryTextBlock	Perkins Mid Cap Value Fund seeks capital appreciation.
Expense [Heading]	rr_ExpenseHeading	FEES AND EXPENSES OF THE FUND
Expense Narrative [Text Block]	rr_ExpenseNarrativeTextBlock	This table describes the fees and expenses that you may pay if you buy and hold Shares of the Fund.
Operating Expenses Caption [Text]	rr_OperatingExpensesCaption	ANNUAL FUND OPERATING EXPENSES (expenses that you pay each year as a percentage of the value of your investment)
Portfolio Turnover [Heading]	rr_PortfolioTurnoverHeading	Portfolio Turnover:
Portfolio Turnover [Text Block]	rr_PortfolioTurnoverTextBlock	The Fund pays transaction costs, such as commissions, when it buys and sells securities (or “turns over” its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when Fund shares are held in a taxable account. These costs, which are not reflected in annual fund operating expenses or in the Example, affect the Fund’s performance. During the most recent fiscal year, the Fund’s portfolio turnover rate was 60% of the average value of its portfolio.
Portfolio Turnover, Rate	rr_PortfolioTurnoverRate	60.00%
Expense Example [Heading]	rr_ExpenseExampleHeading	EXAMPLE:
Expense Example by Year [Heading]	rr_ExpenseExampleByYearHeading	The Example assumes that you invest $10,000 in the Fund for the time periods indicated, reinvest all dividends and distributions, and then redeem all of your Shares at the end of each period. The Example also assumes that your investment has a 5% return each year and that the Fund’s operating expenses remain the same. Although your actual costs may be higher or lower, based on these assumptions your costs would be:
Expense Example Narrative [Text Block]	rr_ExpenseExampleNarrativeTextBlock	The Example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds.
Strategy [Heading]	rr_StrategyHeading	PRINCIPAL INVESTMENT STRATEGIES
Strategy Narrative [Text Block]	rr_StrategyNarrativeTextBlock	The Fund pursues its investment objective by investing primarily in common stocks selected for their capital appreciation potential. The Fund primarily invests in the common stocks of mid-sized companies whose stock prices the portfolio managers believe to be undervalued. The Fund invests, under normal circumstances, at least 80% of its net assets in equity securities of companies whose market capitalization falls, at the time of purchase, within the 12-month average of the capitalization range of the Russell Midcap® Value Index. This average is updated monthly. The market capitalizations within the index will vary, but as of June 30, 2013, they ranged from approximately $487 million to $30.3 billion. The Fund may also invest in foreign equity and debt securities, which may include investments in emerging markets. The Fund may invest, under normal circumstances, up to 20% of its net assets in securities of companies having market capitalizations outside of the aforementioned market capitalization ranges. In addition, when the portfolio managers believe that market conditions are unfavorable for investing, or when they are otherwise unable to locate attractive investment opportunities, the Fund may invest up to 20% of its net assets in cash or similar investments. The Fund focuses on companies that have fallen out of favor with the market or that appear to be temporarily misunderstood by the investment community. The Fund’s portfolio managers generally look for companies with: strong balance sheets and solid recurring free cash flows attractive relative and absolute valuation ratios or that have underperformed recently favorable reward to risk characteristics The Fund may invest in equity and debt securities of real estate-related companies. Such companies may include those in the real estate industry or real estate-related industries. These securities may include common stocks, preferred stocks, and other equity securities, including, but not limited to, mortgage-backed securities, real estate-backed securities, securities of real estate investment trusts (“REITs”) and similar REIT-like entities. A REIT is a trust that invests in real estate-related projects, such as properties, mortgage loans, and construction loans. REITs are generally categorized as equity, mortgage, or hybrid REITs. A REIT may be listed on an exchange or traded over-the-counter. The Fund may also invest its assets in derivatives, which are instruments that have a value derived from, or directly linked to, an underlying asset, such as equity securities, fixed-income securities, commodities, currencies, interest rates, or market indices. The Fund from time to time may buy and sell put and call options, particularly on market indices, for hedging purposes (to offset risks associated with an investment, currency exposure, or market conditions) and to enhance returns. The Fund’s exposure to derivatives will vary, is not limited to those derivatives listed, and could be significant at times. For purposes of meeting its 80% investment policy, the Fund may include derivatives that have characteristics similar to the securities in which the Fund may directly invest.
Risk [Heading]	rr_RiskHeading	PRINCIPAL INVESTMENT RISKS
Risk Narrative [Text Block]	rr_RiskNarrativeTextBlock	The biggest risk is that the Fund’s returns will vary, and you could lose money. The Fund is designed for long-term investors seeking an equity portfolio, including common stocks. Common stocks tend to be more volatile than many other investment choices. Value Investing Risk. Because different types of stocks tend to shift in and out of favor depending on market and economic conditions, “value” stocks may perform differently than other types of stocks and from the market as a whole, and can continue to be undervalued by the market for long periods of time. It is also possible that a value stock will never appreciate to the extent expected by the portfolio managers. When the Fund’s investments in cash or similar investments increase due to a lack of favorable investment opportunities or other extraordinary factors, the Fund may not participate in market advances or declines to the same extent that it would if the Fund had been fully invested. Market Risk. The value of the Fund’s portfolio may decrease if the value of an individual company or security, or multiple companies or securities, in the portfolio decreases or if the portfolio managers’ belief about a company’s intrinsic worth is incorrect. Further, regardless of how well individual companies or securities perform, the value of the Fund’s portfolio could also decrease if there are deteriorating economic or market conditions. It is important to understand that the value of your investment may fall, sometimes sharply, in response to changes in the market, and you could lose money. Mid-Sized Companies Risk. The Fund’s investments in securities issued by mid-sized companies may involve greater risks than are customarily associated with larger, more established companies. Securities issued by mid-sized companies tend to be more volatile than securities issued by larger or more established companies and may underperform as compared to the securities of larger companies. Real Estate Securities Risk. The Fund’s performance may be affected by the risks associated with investments in real estate-related companies. The value of real estate-related companies’ securities is sensitive to changes in real estate values and rental income, property taxes, interest rates, tax and regulatory requirements, supply and demand, and the management skill and creditworthiness of the company. Investments in REITs involve the same risks as other real estate investments. In addition, a REIT could fail to qualify for tax-free pass-through of its income under the Internal Revenue Code or fail to maintain its exemption from registration under the Investment Company Act of 1940, as amended, which could produce adverse economic consequences for the REIT and its investors, including the Fund. Foreign Exposure Risk. The Fund may have exposure to foreign markets as a result of its investments in foreign securities, including investments in emerging markets, which can be more volatile than the U.S. markets. As a result, its returns and net asset value may be affected to a large degree by fluctuations in currency exchange rates or political or economic conditions in a particular country. In some foreign markets, there may not be protection against failure by other parties to complete transactions. It may not be possible for the Fund to repatriate capital, dividends, interest, and other income from a particular country or governmental entity. In addition, a market swing in one or more countries or regions where the Fund has invested a significant amount of its assets may have a greater effect on the Fund’s performance than it would in a more geographically diversified portfolio. To the extent the Fund invests in foreign debt securities, such investments are sensitive to changes in interest rates. Additionally, investments in securities of foreign governments involve the risk that a foreign government may not be willing or able to pay interest or repay principal when due. Derivatives Risk. Derivatives can be highly volatile and involve risks in addition to the risks of the underlying referenced securities. Gains or losses from a derivative investment can be substantially greater than the derivative’s original cost, and can therefore involve leverage. Leverage may cause the Fund to be more volatile than if it had not used leverage. Derivatives can be complex instruments and may involve analysis that differs from that required for other investment types used by the Fund. If the value of a derivative does not correlate well with the particular market or other asset class to which the derivative is intended to provide exposure, the derivative may not produce the anticipated result. Derivatives can also reduce the opportunity for gain or result in losses by offsetting positive returns in other investments. Derivatives can be less liquid than other types of investments and entail the risk that the counterparty will default on its payment obligations. If the counterparty to a derivative transaction defaults, the Fund would risk the loss of the net amount of the payments that it contractually is entitled to receive. To the extent the Fund enters into short derivative positions, the Fund may be exposed to risks similar to those associated with short sales, including the risk that the Fund’s losses are theoretically unlimited. An investment in the Fund is not a bank deposit and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency.
Risk Lose Money [Text]	rr_RiskLoseMoney	The biggest risk is that the Fund’s returns will vary, and you could lose money.
Risk Not Insured Depository Institution [Text]	rr_RiskNotInsuredDepositoryInstitution	An investment in the Fund is not a bank deposit and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency.
Bar Chart and Performance Table [Heading]	rr_BarChartAndPerformanceTableHeading	PERFORMANCE INFORMATION
Performance Narrative [Text Block]	rr_PerformanceNarrativeTextBlock	The following information provides some indication of the risks of investing in the Fund by showing how the Fund’s performance has varied over time. The performance shown for periods following April 21, 2003, reflects the fees and expenses of Class L Shares (formerly named Institutional Shares), net of any applicable fee and expense limitations or waivers. The performance shown for Class L Shares for the periods from May 17, 2002 to April 17, 2003, reflects the historical performance of Berger Mid Cap Value Fund – Institutional Shares (as a result of a prior reorganization of Berger Mid Cap Value Fund – Institutional Shares into the Fund’s Class L Shares). For the periods prior to May 17, 2002, the performance shown reflects the historical performance of Berger Mid Cap Value Fund – Investor Shares. The bar chart depicts the change in performance from year to year during the periods indicated. The table compares the Fund’s average annual returns for the periods indicated to a broad-based securities market index. The index is not actively managed and is not available for direct investment. All figures assume reinvestment of dividends and distributions. For certain periods, the Fund’s performance reflects the effect of expense waivers. Without the effect of these expense waivers, the performance shown would have been lower. The Fund’s past performance (before and after taxes) does not necessarily indicate how it will perform in the future. Updated performance information is available at janus.com/advisor/mutual-funds or by calling 1-877-335-2687.
Performance Information Illustrates Variability of Returns [Text]	rr_PerformanceInformationIllustratesVariabilityOfReturns	The following information provides some indication of the risks of investing in the Fund by showing how the Fund’s performance has varied over time. The bar chart depicts the change in performance from year to year during the periods indicated.
Performance Additional Market Index [Text]	rr_PerformanceAdditionalMarketIndex	The table compares the Fund’s average annual returns for the periods indicated to a broad-based securities market index. The index is not actively managed and is not available for direct investment. All figures assume reinvestment of dividends and distributions.
Performance Availability Phone [Text]	rr_PerformanceAvailabilityPhone	1-877-335-2687
Performance Availability Website Address [Text]	rr_PerformanceAvailabilityWebSiteAddress	janus.com/advisor/mutual-funds
Performance Past Does Not Indicate Future [Text]	rr_PerformancePastDoesNotIndicateFuture	The Fund’s past performance (before and after taxes) does not necessarily indicate how it will perform in the future.
Bar Chart [Heading]	rr_BarChartHeading	Annual Total Returns for Class L Shares (calendar year-end)
Bar Chart Closing [Text Block]	rr_BarChartClosingTextBlock	Best Quarter:  Second Quarter 2003  17.19%          Worst Quarter:  Fourth Quarter 2008  −19.56%
Year to Date Return, Label	rr_YearToDateReturnLabel	The Fund’s year-to-date return as of the calendar quarter ended September 30, 2013 was 17.54%.
Performance Table Heading	rr_PerformanceTableHeading	Average Annual Total Returns (periods ended 12/31/12)	[1]
Performance Table Uses Highest Federal Rate	rr_PerformanceTableUsesHighestFederalRate	After-tax returns are calculated using the historically highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes.
Performance Table Not Relevant to Tax Deferred	rr_PerformanceTableNotRelevantToTaxDeferred	Actual after-tax returns depend on your individual tax situation and may differ from those shown in the preceding table. The after-tax return information shown above does not apply to Fund shares held through a tax-deferred account, such as a 401(k) plan or an IRA.
Performance Table Explanation after Tax Higher	rr_PerformanceTableExplanationAfterTaxHigher	If the Fund incurs a loss, which generates a tax benefit, the Return After Taxes on Distributions and Sale of Fund Shares may exceed the Fund’s other return figures.
Performance Table Narrative	rr_PerformanceTableNarrativeTextBlock	The Russell Midcap® Value Index measures the performance of those Russell Midcap® companies with lower price-to-book ratios and lower forecasted growth values. The stocks are also members of the Russell 1000® Value Index. This index is used to calculate the performance fee adjustment. After-tax returns are calculated using distributions for the Fund’s Class L Shares (formerly named Institutional Shares) for the periods following April 21, 2003; for Berger Mid Cap Value Fund – Institutional Shares for the period May 17, 2002 to April 17, 2003; and for Berger Mid Cap Value Fund – Investor Shares for periods prior to May 17, 2002. If Class L Shares of the Fund had been available during these earlier periods, distributions may have been different and thus, after-tax returns may have been different from those shown. After-tax returns are calculated using the historically highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes. Actual after-tax returns depend on your individual tax situation and may differ from those shown in the preceding table. The after-tax return information shown above does not apply to Fund shares held through a tax-deferred account, such as a 401(k) plan or an IRA.
Performance Table Closing [Text Block]	rr_PerformanceTableClosingTextBlock	Updated performance information is available at janus.com/advisor/mutual-funds or by calling 1-877-335-2687.
Perkins Mid Cap Value Fund | Class L Shares | Class L
Risk/Return:	rr_RiskReturnAbstract
Operating Expenses Column [Text]	rr_OperatingExpensesColumnName	Class L
Management Fees (may adjust up or down)	rr_ManagementFeesOverAssets	0.48%
Other Expenses	rr_OtherExpensesOverAssets	0.29%
Total Annual Fund Operating Expenses	rr_ExpensesOverAssets	0.77%
Expense Example, By Year, Column [Text]	rr_ExpenseExampleByYearColumnName	Class L Shares
1 Year	rr_ExpenseExampleYear01	$ 79
3 Years	rr_ExpenseExampleYear03	246
5 Years	rr_ExpenseExampleYear05	428
10 Years	rr_ExpenseExampleYear10	$ 954
2003	rr_AnnualReturn2003	39.77%
2004	rr_AnnualReturn2004	18.56%
2005	rr_AnnualReturn2005	10.53%
2006	rr_AnnualReturn2006	15.42%
2007	rr_AnnualReturn2007	7.56%
2008	rr_AnnualReturn2008	(27.19%)
2009	rr_AnnualReturn2009	30.74%
2010	rr_AnnualReturn2010	15.01%
2011	rr_AnnualReturn2011	(2.33%)
2012	rr_AnnualReturn2012	10.47%
Bar Chart, Year to Date Return, Date	rr_BarChartYearToDateReturnDate	Sep. 30, 2013
Bar Chart, Year to Date Return	rr_BarChartYearToDateReturn	17.54%
Highest Quarterly Return, Label	rr_HighestQuarterlyReturnLabel	Best Quarter:
Highest Quarterly Return, Date	rr_BarChartHighestQuarterlyReturnDate	Jun. 30, 2003
Highest Quarterly Return	rr_BarChartHighestQuarterlyReturn	17.19%
Lowest Quarterly Return, Label	rr_LowestQuarterlyReturnLabel	Worst Quarter:
Lowest Quarterly Return, Date	rr_BarChartLowestQuarterlyReturnDate	Dec. 31, 2008
Lowest Quarterly Return	rr_BarChartLowestQuarterlyReturn	(19.56%)
Perkins Mid Cap Value Fund | Class L Shares | Return Before Taxes | Class L
Risk/Return:	rr_RiskReturnAbstract
Column	rr_AverageAnnualReturnColumnName	Class L Shares
Label	rr_AverageAnnualReturnLabel	Return Before Taxes
1 Year	rr_AverageAnnualReturnYear01	10.47%
5 Years	rr_AverageAnnualReturnYear05	3.39%
10 Years	rr_AverageAnnualReturnYear10	10.39%
Since Inception of Predecessor Fund	rr_AverageAnnualReturnSinceInception	11.82%
Inception Date	rr_AverageAnnualReturnInceptionDate	Aug. 12, 1998
Perkins Mid Cap Value Fund | Class L Shares | Return After Taxes on Distributions | Class L
Risk/Return:	rr_RiskReturnAbstract
Column	rr_AverageAnnualReturnColumnName	Class L Shares
Label	rr_AverageAnnualReturnLabel	Return After Taxes on Distributions
1 Year	rr_AverageAnnualReturnYear01	9.79%
5 Years	rr_AverageAnnualReturnYear05	2.72%
10 Years	rr_AverageAnnualReturnYear10	9.18%
Since Inception of Predecessor Fund	rr_AverageAnnualReturnSinceInception	10.40%
Inception Date	rr_AverageAnnualReturnInceptionDate	Aug. 12, 1998
Perkins Mid Cap Value Fund | Class L Shares | Return After Taxes on Distributions and Sale of Fund Shares | Class L
Risk/Return:	rr_RiskReturnAbstract
Column	rr_AverageAnnualReturnColumnName	Class L Shares
Label	rr_AverageAnnualReturnLabel	Return After Taxes on Distributions and Sale of Fund Shares	[2]
1 Year	rr_AverageAnnualReturnYear01	7.72%
5 Years	rr_AverageAnnualReturnYear05	2.78%
10 Years	rr_AverageAnnualReturnYear10	8.84%
Since Inception of Predecessor Fund	rr_AverageAnnualReturnSinceInception	10.03%
Inception Date	rr_AverageAnnualReturnInceptionDate	Aug. 12, 1998
Perkins Mid Cap Value Fund | Class L Shares | Russell Midcap® Value Index (reflects no deduction for expenses, fees, or taxes)
Risk/Return:	rr_RiskReturnAbstract
Label	rr_AverageAnnualReturnLabel	Russell Midcap® Value Index
1 Year	rr_AverageAnnualReturnYear01	18.51%
5 Years	rr_AverageAnnualReturnYear05	3.79%
10 Years	rr_AverageAnnualReturnYear10	10.63%
Since Inception of Predecessor Fund	rr_AverageAnnualReturnSinceInception	8.42%
Inception Date	rr_AverageAnnualReturnInceptionDate	Aug. 12, 1998

[1] Fund returns for periods prior to the Fund's adoption of share classes reflect a 0.25% 12b-1 fee, which has not been paid by the Class L Shares (formerly named Institutional Shares) since the class commenced investment operations on May 17, 2002.

[2] If the Fund incurs a loss, which generates a tax benefit, the Return After Taxes on Distributions and Sale of Fund Shares may exceed the Fund’s other return figures.

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Perkins Small Cap Value Fund | Class A, C, S, I, N, R, T Shares

FUND SUMMARY

Perkins Small Cap Value Fund

INVESTMENT OBJECTIVE

Perkins Small Cap Value Fund seeks capital appreciation.

FEES AND EXPENSES OF THE FUND

This table describes the fees and expenses that you may pay if you buy and hold Shares of the Fund. Each share class has different expenses, but represents an investment in the same Fund.

For Class A Shares, you may qualify for sales charge discounts if you and your family invest, or agree to invest in the future, at least $50,000 in the Fund or in other Janus mutual funds. More information about these and other discounts, as well as eligibility requirements for each share class, is available from your financial professional and in the “Purchases” section on page 66 of the Fund’s Prospectus and in the “Purchases” section on page 70 of the Fund’s Statement of Additional Information.

SHAREHOLDER FEES
(fees paid directly from your investment)

Shareholder Fees Perkins Small Cap Value Fund Class A, C, S, I, N, R, T Shares	Class A	Class C	Class S	Class I	Class N	Class R	Class T
Shareholder Fees Column [Text]	Class A	Class C	Class S	Class I	Class N	Class R	Class T
Maximum Sales Charge (load) Imposed on Purchases (as a percentage of offering price)	5.75%	none	none	none	none	none	none
Maximum Deferred Sales Charge (load) (as a percentage of the lower of original purchase price or redemption proceeds)	none	1.00%	none	none	none	none	none

ANNUAL FUND OPERATING EXPENSES
(expenses that you pay each year as a percentage of the value of your investment)

Annual Fund Operating Expenses Perkins Small Cap Value Fund Class A, C, S, I, N, R, T Shares	Class A	Class C	Class S	Class I	Class N	Class R	Class T
Operating Expenses Column [Text]	Class A	Class C	Class S	Class I	Class N	Class R	Class T
Management Fees (may adjust up or down)	0.56%	0.56%	0.56%	0.56%	0.56%	0.56%	0.56%
Distribution/Service (12b-1) Fees	0.25%	1.00%	0.25%	none	none	0.50%	none
Other Expenses	0.19%	0.30%	0.29%	0.15%	0.04%	0.29%	0.29%
Total Annual Fund Operating Expenses	1.00%	1.86%	1.10%	0.71%	0.60%	1.35%	0.85%

EXAMPLE:

The Example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds.

The Example assumes that you invest $10,000 in the Fund for the time periods indicated and reinvest all dividends and distributions. The Example also assumes that your investment has a 5% return each year and that the Fund’s operating expenses remain the same. Although your actual costs may be higher or lower, based on these assumptions your costs would be:

If Shares are redeemed:

Expense Example Perkins Small Cap Value Fund Class A, C, S, I, N, R, T Shares (USD $)	Expense Example, By Year, Column [Text]	1 Year	3 Years	5 Years	10 Years
Class A	Class A Shares	671	875	1,096	1,729
Class C	Class C Shares	289	585	1,006	2,180
Class S	Class S Shares	112	350	606	1,340
Class I	Class I Shares	73	227	395	883
Class N	Class N Shares	61	192	335	750
Class R	Class R Shares	137	428	739	1,624
Class T	Class T Shares	87	271	471	1,049

If Shares are not redeemed:

Expense Example, No Redemption Perkins Small Cap Value Fund Class A, C, S, I, N, R, T Shares (USD $)	Expense Example, No Redemption, By Year, Column [Text]	1 Year	3 Years	5 Years	10 Years
Class A	Class A Shares	671	875	1,096	1,729
Class C	Class C Shares	189	585	1,006	2,180
Class S	Class S Shares	112	350	606	1,340
Class I	Class I Shares	73	227	395	883
Class N	Class N Shares	61	192	335	750
Class R	Class R Shares	137	428	739	1,624
Class T	Class T Shares	87	271	471	1,049

Portfolio Turnover:

The Fund pays transaction costs, such as commissions, when it buys and sells securities (or “turns over” its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when Fund shares are held in a taxable account. These costs, which are not reflected in annual fund operating expenses or in the Example, affect the Fund’s performance. During the most recent fiscal year, the Fund’s portfolio turnover rate was 60% of the average value of its portfolio.

PRINCIPAL INVESTMENT STRATEGIES

The Fund pursues its investment objective by investing primarily in the common stocks of small companies whose stock prices are believed to be undervalued by the Fund’s portfolio managers. The Fund invests, under normal circumstances, at least 80% of its net assets in equity securities of small companies whose market capitalization, at the time of initial purchase, is less than the 12-month average of the maximum market capitalization for companies included in the Russell 2000^® Value Index. This average is updated monthly. The market capitalizations within the index will vary, but as of June 30, 2013, they ranged from approximately $23 million to $5.6 billion. The Fund may also invest in foreign equity and debt securities, which may include investments in emerging markets. The Fund may invest, under normal circumstances, up to 20% of its net assets in securities of companies having market capitalizations outside of the aforementioned market capitalization ranges. In addition, when the portfolio managers believe that market conditions are unfavorable for investing, or when they are otherwise unable to locate attractive investment opportunities, the Fund may invest up to 20% of its net assets in cash or similar investments.

The Fund’s securities selection focuses on companies that are out of favor with markets or have not yet been discovered by the broader investment community. The Fund’s portfolio managers generally look for companies with:

• strong balance sheets and solid recurring free cash flows
• attractive relative and absolute valuation ratios or that have underperformed recently
• favorable reward to risk characteristics

The portfolio managers’ philosophy is to weigh a security’s downside risk before considering its upside potential, which may help provide an element of capital preservation.

PRINCIPAL INVESTMENT RISKS

The biggest risk is that the Fund’s returns will vary, and you could lose money. The Fund is designed for long-term investors seeking an equity portfolio, including common stocks. Common stocks tend to be more volatile than many other investment choices.

Value Investing Risk. Because different types of stocks tend to shift in and out of favor depending on market and economic conditions, “value” stocks may perform differently than other types of stocks and from the market as a whole, and can continue to be undervalued by the market for long periods of time. It is also possible that a value stock will never appreciate to the extent expected by the portfolio managers. When the Fund’s investments in cash or similar investments increase due to a lack of favorable investment opportunities or other extraordinary factors, the Fund may not participate in market advances or declines to the same extent that it would if the Fund had been fully invested.

Market Risk. The value of the Fund’s portfolio may decrease if the value of an individual company or security, or multiple companies or securities, in the portfolio decreases or if the portfolio managers’ belief about a company’s intrinsic worth is incorrect. Further, regardless of how well individual companies or securities perform, the value of the Fund’s portfolio could also decrease if there are deteriorating economic or market conditions. It is important to understand that the value of your investment may fall, sometimes sharply, in response to changes in the market, and you could lose money.

Small-Sized Companies Risk. The Fund’s investments in securities issued by small-sized companies, which can include smaller, start-up companies offering emerging products or services, may involve greater risks than are customarily associated with larger, more established companies. Securities issued by small-sized companies tend to be more volatile and somewhat more speculative than securities issued by larger or more established companies and may underperform as compared to the securities of larger companies.

Real Estate Securities Risk. The Fund’s performance may be affected by the risks associated with investments in real estate-related companies. The value of real estate-related companies’ securities is sensitive to changes in real estate values and rental income, property taxes, interest rates, tax and regulatory requirements, supply and demand, and the management skill and creditworthiness of the company. Investments in real estate investment trusts (“REITs”) involve the same risks as other real estate investments. In addition, a REIT could fail to qualify for tax-free pass-through of its income under the Internal Revenue Code or fail to maintain its exemption from registration under the Investment Company Act of 1940, as amended, which could produce adverse economic consequences for the REIT and its investors, including the Fund.

An investment in the Fund is not a bank deposit and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency.

PERFORMANCE INFORMATION

The following information provides some indication of the risks of investing in the Fund by showing how the Fund’s performance has varied over time. Class T Shares (formerly named Class J Shares) of the Fund commenced operations with the Fund’s inception. Class A Shares, Class C Shares, Class S Shares, Class I Shares, and Class R Shares of the Fund commenced operations on July 6, 2009. Class N Shares of the Fund commenced operations on May 31, 2012.

• The performance shown for Class T Shares for periods following April 21, 2003, reflects the fees and expenses of Class T Shares in effect during the periods shown, net of any applicable fee and expense limitations or waivers. For the periods prior to April 21, 2003, the performance shown for Class T Shares reflects the historical performance of Berger Small Cap Value Fund – Investor Shares (as a result of a prior reorganization of Berger Small Cap Value Fund – Investor Shares into the Fund’s former Class J Shares).
• The performance shown for Class A Shares, Class C Shares, Class S Shares, and Class R Shares reflects the performance of the Fund’s Class J Shares (formerly named Investor Shares) from April 21, 2003 to July 6, 2009, calculated using the fees and expenses of each respective share class, without the effect of any fee and expense limitations or waivers. For periods prior to April 21, 2003, the performance shown for Class A Shares, Class C Shares, Class S Shares, and Class R Shares reflects the historical performance of Berger Small Cap Value Fund – Investor Shares (as a result of a prior reorganization of Berger Small Cap Value Fund – Investor Shares into the Fund’s former Class J Shares), calculated using the fees and expenses of each respective share class, without the effect of any fee and expense limitations or waivers.
• The performance shown for Class I Shares reflects the performance of the Fund’s Class J Shares (formerly named Investor Shares) from April 21, 2003 to July 6, 2009, calculated using the fees and expenses of Class J Shares, net of any applicable fee and expense limitations or waivers. For the periods prior to April 21, 2003, the performance shown for Class I Shares reflects the historical performance of Berger Small Cap Value Fund – Investor Shares (as a result of a prior reorganization of Berger Small Cap Value Fund – Investor Shares into the Fund’s former Class J Shares), calculated using the fees and expenses of Class J Shares, net of any applicable fee and expense limitations or waivers.
• The performance shown for Class N Shares reflects the performance of the Fund’s Class T Shares from July 6, 2009 to May 31, 2012, calculated using the fees and expenses of Class T Shares, net of any applicable fee and expense limitations or waivers. For the period from April 21, 2003 to July 6, 2009, the performance shown for Class N Shares reflects the performance of the Fund’s Class J Shares (formerly named Investor Shares), calculated using the fees and expenses of Class J Shares, net of any applicable fee and expense limitations or waivers. For the periods prior to April 21, 2003, the performance shown for Class N Shares reflects the historical performance of Berger Small Cap Value Fund – Investor Shares (as a result of a prior reorganization of Berger Small Cap Value Fund – Investor Shares into the Fund’s former Class J Shares), calculated using the fees and expenses of Class J Shares, net of any applicable fee and expense limitations or waivers.

If Class A Shares, Class C Shares, Class S Shares, Class I Shares, and Class R Shares of the Fund had been available during periods prior to July 6, 2009, or Class N Shares of the Fund had been available during periods prior to May 31, 2012, the performance shown for each respective share class may have been different. The performance shown for periods following the Fund’s commencement of Class A Shares, Class C Shares, Class S Shares, Class I Shares, Class N Shares, and Class R Shares reflects the fees and expenses of each respective share class, net of any applicable fee and expense limitations or waivers.

The bar chart depicts the change in performance from year to year during the periods indicated. The bar chart figures do not include any applicable sales charges that an investor may pay when they buy or sell Class A Shares or Class C Shares of the Fund. If sales charges were included, the returns would be lower. The table compares the Fund’s average annual returns for the periods indicated to a broad-based securities market index. The index is not actively managed and is not available for direct investment. All figures assume reinvestment of dividends and distributions. For certain periods, the Fund’s performance reflects the effect of expense waivers. Without the effect of these expense waivers, the performance shown would have been lower.

The Fund’s past performance (before and after taxes) does not necessarily indicate how it will perform in the future. Updated performance information is available at janus.com/advisor/mutual-funds or by calling 1-877-335-2687.

Annual Total Returns for Class T Shares (calendar year-end)

Best Quarter:  Second Quarter 2009  23.04%          Worst Quarter:  Fourth Quarter 2008  −18.83%

The Fund’s year-to-date return as of the calendar quarter ended September 30, 2013 was 18.46%.

Average Annual Total Returns (periods ended 12/31/12)

Average Annual Total Returns Perkins Small Cap Value Fund Class A, C, S, I, N, R, T Shares	Column	Label		1 Year	5 Years	10 Years
Class T Return Before Taxes	Class T Shares	Return Before Taxes		8.99%	5.80%	10.00%
Class T Return After Taxes on Distributions	Class T Shares	Return After Taxes on Distributions		8.13%	4.59%	8.09%
Class T Return After Taxes on Distributions and Sale of Fund Shares	Class T Shares	Return After Taxes on Distributions and Sale of Fund Shares	[1]	7.01%	4.65%	8.23%
Class A Return Before Taxes	Class A Shares	Return Before Taxes	[2]	2.52%	4.36%	9.09%
Class C Return Before Taxes	Class C Shares	Return Before Taxes	[3]	6.95%	4.77%	8.96%
Class S Return Before Taxes	Class S Shares	Return Before Taxes		8.76%	5.55%	9.74%
Class I Return Before Taxes	Class I Shares	Return Before Taxes		9.13%	5.80%	10.00%
Class N Return Before Taxes	Class N Shares	Return Before Taxes		8.99%	5.80%	10.00%
Class R Return Before Taxes	Class R Shares	Return Before Taxes		8.43%	5.27%	9.47%
Russell 2000® Value Index (reflects no deduction for expenses, fees, or taxes)		Russell 2000® Value Index		18.05%	3.55%	9.50%

The Russell 2000^® Value Index measures the performance of those Russell 2000^® companies with lower price-to-book ratios and lower forecasted growth values. This index is used to calculate the performance fee adjustment.

After-tax returns are calculated using distributions for the Fund’s Class T Shares (formerly named Class J Shares) for the periods following April 21, 2003; and for Berger Small Cap Value Fund – Investor Shares for periods prior to April 21, 2003. If Class T Shares of the Fund had been available during the periods prior to April 21, 2003, distributions may have been different and thus, after-tax returns may have been different from those shown. After-tax returns are calculated using the historically highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes. Actual after-tax returns depend on your individual tax situation and may differ from those shown in the preceding table. The after-tax return information shown above does not apply to Fund shares held through a tax-deferred account, such as a 401(k) plan or an IRA.

After-tax returns are only shown for Class T Shares of the Fund. After-tax returns for the other classes of Shares will vary from those shown for Class T Shares due to varying sales charges (as applicable), fees, and expenses among the classes.

[1] If the Fund incurs a loss, which generates a tax benefit, the Return After Taxes on Distributions and Sale of Fund Shares may exceed the Fund’s other return figures.

[2] Calculated assuming maximum permitted sales loads.

[3] The one year return is calculated to include the contingent deferred sales charge.

XML

Label

Element

Value

Risk/Return:

rr_RiskReturnAbstract

Registrant Name

dei_EntityRegistrantName

JANUS INVESTMENT FUND

Prospectus Date

rr_ProspectusDate

Oct. 28, 2013

Janus Government Money Market Fund | Class T Shares

Risk/Return:

rr_RiskReturnAbstract

Risk/Return [Heading]

rr_RiskReturnHeading

FUND SUMMARY

Janus Government Money Market Fund

Objective [Heading]

rr_ObjectiveHeading

INVESTMENT OBJECTIVES

Objective, Primary [Text Block]

rr_ObjectivePrimaryTextBlock

Janus Government Money Market Fund seeks capital preservation and liquidity with current income as a secondary objective.

Expense [Heading]

rr_ExpenseHeading

FEES AND EXPENSES OF THE FUND

Expense Narrative [Text Block]

rr_ExpenseNarrativeTextBlock

This table describes the fees and expenses that you may pay if you buy and hold Shares of the Fund.

Operating Expenses Caption [Text]

rr_OperatingExpensesCaption

ANNUAL FUND OPERATING EXPENSES
(expenses that you pay each year as a percentage of the value of your investment)

Expense Example [Heading]

rr_ExpenseExampleHeading

EXAMPLE:

Expense Example by Year [Heading]

rr_ExpenseExampleByYearHeading

The Example assumes that you invest $10,000 in the Fund for the time periods indicated, reinvest all dividends and distributions, and then redeem all of your Shares at the end of each period. The Example also assumes that your investment has a 5% return each year and that the Fund’s operating expenses remain the same. Although your actual costs may be higher or lower, based on these assumptions your costs would be:

Expense Example Narrative [Text Block]

rr_ExpenseExampleNarrativeTextBlock

The Example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds.

Strategy [Heading]

rr_StrategyHeading

PRINCIPAL INVESTMENT STRATEGIES

Strategy Narrative [Text Block]

rr_StrategyNarrativeTextBlock

The Fund pursues its investment objectives by investing exclusively in obligations issued and/or guaranteed as to principal and interest by the United States Government or by its agencies and instrumentalities, and repurchase agreements secured by such obligations. Although U.S. Government agencies and instrumentalities may be chartered or sponsored by Acts of Congress, their securities are not issued by, and may not be guaranteed by (i.e., backed by the full faith and credit of), the United States Treasury. Some government agency and instrumentality securities not backed by the full faith and credit of the United States are supported by the issuer’s ability to borrow from the U.S. Treasury, some are supported only by the credit of the issuer, and some are supported by the United States in some other way. For securities not backed by the full faith and credit of the U.S. Treasury, the Fund must look principally to the agency or instrumentality issuing or guaranteeing the securities for repayment and may not be able to assert a claim against the United States if the agency or instrumentality does not meet its commitment. The Fund’s investments in securities issued by U.S. Government agencies and instrumentalities may be significant.

The Fund will:

• invest in high quality, short-term money market instruments that present minimal credit risks, as determined by Janus Capital

• invest only in U.S. dollar-denominated instruments that have a remaining maturity of 397 days or less (as calculated pursuant to Rule 2a-7 under the Investment Company Act of 1940, as amended)

• maintain a dollar-weighted average portfolio maturity of 60 days or less and maintain a dollar-weighted average portfolio life (portfolio maturity measured without reference to any maturity shortening provisions of adjustable rate securities by reference to their interest rate reset dates) of 120 days or less

Risk [Heading]

rr_RiskHeading

PRINCIPAL INVESTMENT RISKS

Risk Narrative [Text Block]

rr_RiskNarrativeTextBlock

Market Risk. The Fund’s yield will vary as the short-term securities in its portfolio mature and the proceeds are reinvested in securities with different interest rates. For capital preservation and liquidity, the Fund may have a greater concentration in short-term securities including, but not limited to, investing up to all of its assets in overnight securities, which may result in a reduction of the Fund’s yield. Over time, the real value of the Fund’s yield may be eroded by inflation. Although the Fund invests only in high-quality, short-term money market instruments, there is a risk that the value of the securities it holds will fall as a result of changes in interest rates, an issuer’s actual or perceived creditworthiness, or an issuer’s ability to meet its obligations. The credit quality of the Fund’s holdings can change rapidly in certain market environments and any downgrade or default of a portfolio security could cause the Fund’s share price or yield to fall.

Collateral Risk. With respect to collateral received in repurchase transactions or other investments, the Fund may have significant exposure to government agencies not secured by the full faith and credit of the United States. Such exposure, depending on market conditions, could have a negative impact on the Fund, including minimizing the value of any collateral.

Money Market Risk. An investment in the Fund is not a bank deposit and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency. Although the Fund seeks to preserve the value of your investment at $1.00 per share, it is possible to lose money by investing in the Fund.

Risk Money Market Fund [Text]

rr_RiskMoneyMarketFund

Money Market Risk. An investment in the Fund is not a bank deposit and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency. Although the Fund seeks to preserve the value of your investment at $1.00 per share, it is possible to lose money by investing in the Fund.

Bar Chart and Performance Table [Heading]

rr_BarChartAndPerformanceTableHeading

PERFORMANCE INFORMATION

Performance Narrative [Text Block]

rr_PerformanceNarrativeTextBlock

The following information provides some indication of the risks of investing in the Fund by showing how the Fund’s performance has varied over time. Class T Shares (formerly named Class J Shares, the initial share class) of the Fund commenced operations with the Fund’s inception. The performance shown for Class T Shares is calculated using the fees and expenses of Class T Shares in effect during the periods shown, net of any applicable fee and expense limitations or waivers.

The bar chart depicts the change in performance from year to year during the periods indicated. The table shows how the Fund’s returns over different periods average out. All figures assume reinvestment of dividends and distributions. For certain periods, the Fund’s performance reflects the effect of expense waivers. Without the effect of these expense waivers, the performance shown would have been lower.

The Fund’s past performance does not necessarily indicate how it will perform in the future. Updated performance information is available at janus.com/advisor/mutual-funds or by calling 1-877-335-2687.

Performance Information Illustrates Variability of Returns [Text]

rr_PerformanceInformationIllustratesVariabilityOfReturns

The following information provides some indication of the risks of investing in the Fund by showing how the Fund’s performance has varied over time.

The bar chart depicts the change in performance from year to year during the periods indicated.

Performance Availability Phone [Text]

rr_PerformanceAvailabilityPhone

1-877-335-2687

Performance Availability Website Address [Text]

rr_PerformanceAvailabilityWebSiteAddress

janus.com/advisor/mutual-funds

Performance Past Does Not Indicate Future [Text]

rr_PerformancePastDoesNotIndicateFuture

The Fund’s past performance does not necessarily indicate how it will perform in the future.

Bar Chart [Heading]

rr_BarChartHeading

Annual Total Returns for Class T Shares (calendar year-end)

Bar Chart Closing [Text Block]

rr_BarChartClosingTextBlock

Best Quarter:  Fourth Quarter 2006  1.21%          Worst Quarter:  Third Quarter 2011  0.00%

Year to Date Return, Label

rr_YearToDateReturnLabel

The Fund’s year-to-date return as of the calendar quarter ended September 30, 2013 was 0.00%.

Performance Table Heading

rr_PerformanceTableHeading

Average Annual Total Returns (periods ended 12/31/12)

Performance Table Closing [Text Block]

rr_PerformanceTableClosingTextBlock

Updated performance information is available at janus.com/advisor/mutual-funds or by calling 1-877-335-2687.

Money Market Seven Day Yield, Caption [Text]

rr_MoneyMarketSevenDayYieldCaption

The 7-day yield on December 31, 2012 was 0.01% for Janus Government Money Market Fund.

Money Market Seven Day Yield

rr_MoneyMarketSevenDayYield

0.01%

Janus Government Money Market Fund | Class T Shares | Class T

Risk/Return:

rr_RiskReturnAbstract

Operating Expenses Column [Text]

rr_OperatingExpensesColumnName

Class T

Management Fees

rr_ManagementFeesOverAssets

0.20%

Other Expenses

rr_OtherExpensesOverAssets

0.53%

Total Annual Fund Operating Expenses

rr_ExpensesOverAssets

0.73%

Expense Example, By Year, Column [Text]

rr_ExpenseExampleByYearColumnName

Class T Shares

1 Year

rr_ExpenseExampleYear01

$ 75

3 Years

rr_ExpenseExampleYear03

233

5 Years

rr_ExpenseExampleYear05

406

10 Years

rr_ExpenseExampleYear10

$ 906

2003

rr_AnnualReturn2003

0.65%

2004

rr_AnnualReturn2004

0.85%

2005

rr_AnnualReturn2005

2.70%

2006

rr_AnnualReturn2006

4.52%

2007

rr_AnnualReturn2007

4.66%

2008

rr_AnnualReturn2008

1.83%

2009

rr_AnnualReturn2009

0.01%

2010

rr_AnnualReturn2010

0.02%

2011

rr_AnnualReturn2011

0.00%

2012

rr_AnnualReturn2012

0.00%

Bar Chart, Year to Date Return, Date

rr_BarChartYearToDateReturnDate

Sep. 30, 2013

Bar Chart, Year to Date Return

rr_BarChartYearToDateReturn

0.00%

Highest Quarterly Return, Label

rr_HighestQuarterlyReturnLabel

Best Quarter:

Highest Quarterly Return, Date

rr_BarChartHighestQuarterlyReturnDate

Dec. 31, 2006

Highest Quarterly Return

rr_BarChartHighestQuarterlyReturn

1.21%

Lowest Quarterly Return, Label

rr_LowestQuarterlyReturnLabel

Worst Quarter:

Lowest Quarterly Return, Date

rr_BarChartLowestQuarterlyReturnDate

Sep. 30, 2011

Lowest Quarterly Return

rr_BarChartLowestQuarterlyReturn

0.00%

Janus Government Money Market Fund | Class T Shares | Return Before Taxes | Class T

Risk/Return:

rr_RiskReturnAbstract

Column

rr_AverageAnnualReturnColumnName

Class T Shares

Label

rr_AverageAnnualReturnLabel

Return Before Taxes

1 Year

rr_AverageAnnualReturnYear01

none

5 Years

rr_AverageAnnualReturnYear05

0.37%

10 Years

rr_AverageAnnualReturnYear10

1.51%

Since Inception

rr_AverageAnnualReturnSinceInception

2.82%

Inception Date

rr_AverageAnnualReturnInceptionDate

Feb. 14, 1995

XML

Label	Element	Value
Risk/Return:	rr_RiskReturnAbstract
Registrant Name	dei_EntityRegistrantName	JANUS INVESTMENT FUND
Prospectus Date	rr_ProspectusDate	Oct. 28, 2013
Perkins Select Value Fund | Class A, C, S, I, N, T Shares
Risk/Return:	rr_RiskReturnAbstract
Risk/Return [Heading]	rr_RiskReturnHeading	FUND SUMMARY Perkins Select Value Fund
Objective [Heading]	rr_ObjectiveHeading	INVESTMENT OBJECTIVE
Objective, Primary [Text Block]	rr_ObjectivePrimaryTextBlock	Perkins Select Value Fund seeks capital appreciation.
Expense [Heading]	rr_ExpenseHeading	FEES AND EXPENSES OF THE FUND
Expense Narrative [Text Block]	rr_ExpenseNarrativeTextBlock	This table describes the fees and expenses that you may pay if you buy and hold Shares of the Fund. Each share class has different expenses, but represents an investment in the same Fund.
Shareholder Fees Caption [Text]	rr_ShareholderFeesCaption	SHAREHOLDER FEES (fees paid directly from your investment)
Operating Expenses Caption [Text]	rr_OperatingExpensesCaption	ANNUAL FUND OPERATING EXPENSES (expenses that you pay each year as a percentage of the value of your investment)
Fee Waiver or Reimbursement over Assets, Date of Termination	rr_FeeWaiverOrReimbursementOverAssetsDateOfTermination	November 1, 2014
Portfolio Turnover [Heading]	rr_PortfolioTurnoverHeading	Portfolio Turnover:
Portfolio Turnover [Text Block]	rr_PortfolioTurnoverTextBlock	The Fund pays transaction costs, such as commissions, when it buys and sells securities (or “turns over” its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when Fund shares are held in a taxable account. These costs, which are not reflected in annual fund operating expenses or in the Example, affect the Fund’s performance. During the most recent fiscal year, the Fund’s portfolio turnover rate was 62% of the average value of its portfolio.
Portfolio Turnover, Rate	rr_PortfolioTurnoverRate	62.00%
Expense Breakpoint Discounts [Text]	rr_ExpenseBreakpointDiscounts	For Class A Shares, you may qualify for sales charge discounts if you and your family invest, or agree to invest in the future, at least $50,000 in the Fund or in other Janus mutual funds. More information about these and other discounts, as well as eligibility requirements for each share class, is available from your financial professional and in the “Purchases” section on page 66 of the Fund’s Prospectus and in the “Purchases” section on page 70 of the Fund’s Statement of Additional Information.
Expense Breakpoint, Minimum Investment Required [Amount]	rr_ExpenseBreakpointMinimumInvestmentRequiredAmount	$ 50,000
Expense Example [Heading]	rr_ExpenseExampleHeading	EXAMPLE:
Expense Example by Year [Heading]	rr_ExpenseExampleByYearHeading	The Example assumes that you invest $10,000 in the Fund for the time periods indicated and reinvest all dividends and distributions. The Example also assumes that your investment has a 5% return each year and that the Fund’s operating expenses without waivers remain the same. Although your actual costs may be higher or lower, based on these assumptions your costs would be:
Expense Example Narrative [Text Block]	rr_ExpenseExampleNarrativeTextBlock	The following Example is based on expenses without waivers. The Example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds.
Expense Example by, Year, Caption [Text]	rr_ExpenseExampleByYearCaption	If Shares are redeemed:
Expense Example, No Redemption, By Year, Caption [Text]	rr_ExpenseExampleNoRedemptionByYearCaption	If Shares are not redeemed:
Strategy [Heading]	rr_StrategyHeading	PRINCIPAL INVESTMENT STRATEGIES
Strategy Narrative [Text Block]	rr_StrategyNarrativeTextBlock	The Fund pursues its investment objective by investing primarily in common stocks in all capitalization ranges selected for their capital appreciation potential. The Fund primarily invests in the common stocks of companies of any size whose stock prices the portfolio managers believe to be undervalued. The Fund may also invest in foreign equity and debt securities, which may include investments in emerging markets. In addition, when the portfolio managers believe that market conditions are unfavorable for investing, or when they are otherwise unable to locate attractive investment opportunities, the Fund’s cash or similar investments may increase. The Fund focuses on companies that have fallen out of favor with the market or that appear to be temporarily misunderstood by the investment community. The Fund’s portfolio managers generally look for companies with: strong balance sheets and solid recurring free cash flows attractive relative and absolute valuation ratios or that have underperformed recently favorable reward to risk characteristics The Fund may invest its assets in derivatives, which are instruments that have a value derived from, or directly linked to, an underlying asset, such as equity securities, fixed-income securities, commodities, currencies, interest rates, or market indices, as substitutes for securities in which the Fund invests. The Fund may invest in derivative instruments (by taking long and/or short positions) for different purposes, including hedging (to offset risks associated with an investment, currency exposure, or market conditions) and to earn income and enhance returns.
Risk [Heading]	rr_RiskHeading	PRINCIPAL INVESTMENT RISKS
Risk Narrative [Text Block]	rr_RiskNarrativeTextBlock	The biggest risk is that the Fund’s returns will vary, and you could lose money. The Fund is designed for long-term investors seeking an equity portfolio, including common stocks. Common stocks tend to be more volatile than many other investment choices. Value Investing Risk. Because different types of stocks tend to shift in and out of favor depending on market and economic conditions, “value” stocks may perform differently than other types of stocks and from the market as a whole, and can continue to be undervalued by the market for long periods of time. It is also possible that a value stock will never appreciate to the extent expected by the portfolio managers. When the Fund’s investments in cash or similar investments increase due to a lack of favorable investment opportunities or other extraordinary factors, the Fund may not participate in market advances or declines to the same extent that it would if the Fund had been fully invested. Market Risk. The value of the Fund’s portfolio may decrease if the value of an individual company or security, or multiple companies or securities, in the portfolio decreases or if the portfolio managers’ belief about a company’s intrinsic worth is incorrect. Further, regardless of how well individual companies or securities perform, the value of the Fund’s portfolio could also decrease if there are deteriorating economic or market conditions. It is important to understand that the value of your investment may fall, sometimes sharply, in response to changes in the market, and you could lose money. Foreign Exposure Risk. The Fund may have significant exposure to foreign markets as a result of its investments in foreign securities, including investments in emerging markets, which can be more volatile than the U.S. markets. As a result, its returns and net asset value may be affected to a large degree by fluctuations in currency exchange rates or political or economic conditions in a particular country. In some foreign markets, there may not be protection against failure by other parties to complete transactions. It may not be possible for the Fund to repatriate capital, dividends, interest, and other income from a particular country or governmental entity. In addition, a market swing in one or more countries or regions where the Fund has invested a significant amount of its assets may have a greater effect on the Fund’s performance than it would in a more geographically diversified portfolio. To the extent the Fund invests in foreign debt securities, such investments are sensitive to changes in interest rates. Additionally, investments in securities of foreign governments involve the risk that a foreign government may not be willing or able to pay interest or repay principal when due. Eurozone Risk. A number of countries in the European Union (“EU”) have experienced severe economic and financial difficulties. As a result, financial markets in the EU have been subject to extreme volatility and declines in asset values and liquidity. Responses to these financial problems by European governments, central banks, and others, including austerity measures and reforms, may not work, may result in social unrest, and may limit future growth and economic recovery or have other unintended consequences. Further defaults or restructurings by governments and others of their debt could have additional adverse effects on economies, financial markets, and asset valuations around the world. To the extent that the Fund has exposure to European markets or to transactions tied to the value of the euro, these events could negatively affect the value and liquidity of the Fund’s investments. Real Estate Securities Risk. The Fund’s performance may be affected by the risks associated with investments in real estate-related companies. The value of real estate-related companies’ securities is sensitive to changes in real estate values and rental income, property taxes, interest rates, tax and regulatory requirements, supply and demand, and the management skill and creditworthiness of the company. Investments in real estate investment trusts (“REITs”) involve the same risks as other real estate investments. In addition, a REIT could fail to qualify for tax-free pass-through of its income under the Internal Revenue Code or fail to maintain its exemption from registration under the Investment Company Act of 1940, as amended, which could produce adverse economic consequences for the REIT and its investors, including the Fund. Derivatives Risk. Derivatives can be highly volatile and involve risks in addition to the risks of the underlying referenced securities. Gains or losses from a derivative investment can be substantially greater than the derivative’s original cost, and can therefore involve leverage. Leverage may cause the Fund to be more volatile than if it had not used leverage. Derivatives can be less liquid than other types of investments and entail the risk that the counterparty will default on its payment obligations. An investment in the Fund is not a bank deposit and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency.
Risk Lose Money [Text]	rr_RiskLoseMoney	The biggest risk is that the Fund’s returns will vary, and you could lose money.
Risk Not Insured Depository Institution [Text]	rr_RiskNotInsuredDepositoryInstitution	An investment in the Fund is not a bank deposit and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency.
Bar Chart and Performance Table [Heading]	rr_BarChartAndPerformanceTableHeading	PERFORMANCE INFORMATION
Performance Narrative [Text Block]	rr_PerformanceNarrativeTextBlock	The following information provides some indication of the risks of investing in the Fund by showing how the Fund’s performance has varied over time. Class A Shares, Class C Shares, Class S Shares, Class I Shares, and Class T Shares of the Fund commenced operations with the Fund’s inception. The performance shown for Class A Shares, Class C Shares, Class S Shares, Class I Shares, and Class T Shares is calculated using the fees and expenses of each respective share class, net of any applicable fee and expense limitations or waivers. The performance shown for Class N Shares reflects the performance of the Fund’s Class I Shares, calculated using the fees and expenses of Class N Shares, without the effect of any fee and expense limitations or waivers. If Class N Shares of the Fund had been available during the periods shown, the performance may have been different. The bar chart depicts the Fund’s performance during the period indicated. The bar chart figures do not include any applicable sales charges that an investor may pay when they buy or sell Class A Shares or Class C Shares of the Fund. If sales charges were included, the returns would be lower. The table compares the Fund’s average annual returns for the periods indicated to a broad-based securities market index. The index is not actively managed and is not available for direct investment. All figures assume reinvestment of dividends and distributions. For certain periods, the Fund’s performance reflects the effect of expense waivers. Without the effect of these expense waivers, the performance shown would have been lower. The Fund’s past performance (before and after taxes) does not necessarily indicate how it will perform in the future. Updated performance information is available at janus.com/advisor/mutual-funds or by calling 1-877-335-2687.
Performance Information Illustrates Variability of Returns [Text]	rr_PerformanceInformationIllustratesVariabilityOfReturns	The following information provides some indication of the risks of investing in the Fund by showing how the Fund’s performance has varied over time. The bar chart depicts the Fund’s performance during the period indicated.
Performance Additional Market Index [Text]	rr_PerformanceAdditionalMarketIndex	The table compares the Fund’s average annual returns for the periods indicated to a broad-based securities market index. The index is not actively managed and is not available for direct investment. All figures assume reinvestment of dividends and distributions.
Performance Availability Phone [Text]	rr_PerformanceAvailabilityPhone	1-877-335-2687
Performance Availability Website Address [Text]	rr_PerformanceAvailabilityWebSiteAddress	janus.com/advisor/mutual-funds
Performance Past Does Not Indicate Future [Text]	rr_PerformancePastDoesNotIndicateFuture	The Fund’s past performance (before and after taxes) does not necessarily indicate how it will perform in the future.
Bar Chart [Heading]	rr_BarChartHeading	Annual Total Returns for Class I Shares (calendar year-end)
Bar Chart Does Not Reflect Sales Loads [Text]	rr_BarChartDoesNotReflectSalesLoads	The bar chart figures do not include any applicable sales charges that an investor may pay when they buy or sell Class A Shares or Class C Shares of the Fund. If sales charges were included, the returns would be lower.
Bar Chart Closing [Text Block]	rr_BarChartClosingTextBlock	Best Quarter:  First Quarter 2012  11.14%          Worst Quarter:  Second Quarter 2012  −4.75%
Year to Date Return, Label	rr_YearToDateReturnLabel	The Fund’s year-to-date return as of the calendar quarter ended September 30, 2013 was 15.57%.
Performance Table Heading	rr_PerformanceTableHeading	Average Annual Total Returns (periods ended 12/31/12)
Performance Table Uses Highest Federal Rate	rr_PerformanceTableUsesHighestFederalRate	After-tax returns are calculated using the historically highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes.
Performance Table Not Relevant to Tax Deferred	rr_PerformanceTableNotRelevantToTaxDeferred	Actual after-tax returns depend on your individual tax situation and may differ from those shown in the preceding table. The after-tax return information shown above does not apply to Fund shares held through a tax-deferred account, such as a 401(k) plan or an IRA.
Performance Table One Class of after Tax Shown [Text]	rr_PerformanceTableOneClassOfAfterTaxShown	After-tax returns are only shown for Class I Shares of the Fund. After-tax returns for the other classes of Shares will vary from those shown for Class I Shares due to varying sales charges (as applicable), fees, and expenses among the classes.
Performance Table Narrative	rr_PerformanceTableNarrativeTextBlock	The Russell 3000® Value Index measures the performance of those Russell 3000® companies with lower price-to-book ratios and lower forecasted growth values. The stocks in the Russell 3000® Value Index are also members of either the Russell 1000® Value Index or the Russell 2000® Value Index. This index is used to calculate the performance fee adjustment. After-tax returns are calculated using the historically highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes. Actual after-tax returns depend on your individual tax situation and may differ from those shown in the preceding table. The after-tax return information shown above does not apply to Fund shares held through a tax-deferred account, such as a 401(k) plan or an IRA. After-tax returns are only shown for Class I Shares of the Fund. After-tax returns for the other classes of Shares will vary from those shown for Class I Shares due to varying sales charges (as applicable), fees, and expenses among the classes.
Performance Table Closing [Text Block]	rr_PerformanceTableClosingTextBlock	Updated performance information is available at janus.com/advisor/mutual-funds or by calling 1-877-335-2687.
Perkins Select Value Fund | Class A, C, S, I, N, T Shares | Class A
Risk/Return:	rr_RiskReturnAbstract
Shareholder Fees Column [Text]	rr_ShareholderFeesColumnName	Class A
Maximum Sales Charge (load) Imposed on Purchases (as a percentage of offering price)	rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice	5.75%
Maximum Deferred Sales Charge (load) (as a percentage of the lower of original purchase price or redemption proceeds)	rr_MaximumDeferredSalesChargeOverOther	none
Operating Expenses Column [Text]	rr_OperatingExpensesColumnName	Class A
Management Fees (may adjust up or down)	rr_ManagementFeesOverAssets	0.63%
Distribution/Service (12b-1) Fees	rr_DistributionAndService12b1FeesOverAssets	0.25%
Other Expenses	rr_OtherExpensesOverAssets	0.45%
Total Annual Fund Operating Expenses	rr_ExpensesOverAssets	1.33%	[1]
Fee Waiver	rr_FeeWaiverOrReimbursementOverAssets	0.19%	[1]
Total Annual Fund Operating Expenses After Fee Waiver	rr_NetExpensesOverAssets	1.14%	[1]
Expense Example, By Year, Column [Text]	rr_ExpenseExampleByYearColumnName	Class A Shares
1 Year	rr_ExpenseExampleYear01	703
3 Years	rr_ExpenseExampleYear03	972
5 Years	rr_ExpenseExampleYear05	1,262
10 Years	rr_ExpenseExampleYear10	2,084
Expense Example, No Redemption, By Year, Column [Text]	rr_ExpenseExampleNoRedemptionByYearColumnName	Class A Shares
1 Year	rr_ExpenseExampleNoRedemptionYear01	703
3 Years	rr_ExpenseExampleNoRedemptionYear03	972
5 Years	rr_ExpenseExampleNoRedemptionYear05	1,262
10 Years	rr_ExpenseExampleNoRedemptionYear10	2,084
Perkins Select Value Fund | Class A, C, S, I, N, T Shares | Class C
Risk/Return:	rr_RiskReturnAbstract
Shareholder Fees Column [Text]	rr_ShareholderFeesColumnName	Class C
Maximum Sales Charge (load) Imposed on Purchases (as a percentage of offering price)	rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice	none
Maximum Deferred Sales Charge (load) (as a percentage of the lower of original purchase price or redemption proceeds)	rr_MaximumDeferredSalesChargeOverOther	1.00%
Operating Expenses Column [Text]	rr_OperatingExpensesColumnName	Class C
Management Fees (may adjust up or down)	rr_ManagementFeesOverAssets	0.63%
Distribution/Service (12b-1) Fees	rr_DistributionAndService12b1FeesOverAssets	1.00%
Other Expenses	rr_OtherExpensesOverAssets	0.40%
Total Annual Fund Operating Expenses	rr_ExpensesOverAssets	2.03%	[1]
Fee Waiver	rr_FeeWaiverOrReimbursementOverAssets	0.20%	[1]
Total Annual Fund Operating Expenses After Fee Waiver	rr_NetExpensesOverAssets	1.83%	[1]
Expense Example, By Year, Column [Text]	rr_ExpenseExampleByYearColumnName	Class C Shares
1 Year	rr_ExpenseExampleYear01	306
3 Years	rr_ExpenseExampleYear03	637
5 Years	rr_ExpenseExampleYear05	1,093
10 Years	rr_ExpenseExampleYear10	2,358
Expense Example, No Redemption, By Year, Column [Text]	rr_ExpenseExampleNoRedemptionByYearColumnName	Class C Shares
1 Year	rr_ExpenseExampleNoRedemptionYear01	206
3 Years	rr_ExpenseExampleNoRedemptionYear03	637
5 Years	rr_ExpenseExampleNoRedemptionYear05	1,093
10 Years	rr_ExpenseExampleNoRedemptionYear10	2,358
Perkins Select Value Fund | Class A, C, S, I, N, T Shares | Class S
Risk/Return:	rr_RiskReturnAbstract
Shareholder Fees Column [Text]	rr_ShareholderFeesColumnName	Class S
Maximum Sales Charge (load) Imposed on Purchases (as a percentage of offering price)	rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice	none
Maximum Deferred Sales Charge (load) (as a percentage of the lower of original purchase price or redemption proceeds)	rr_MaximumDeferredSalesChargeOverOther	none
Operating Expenses Column [Text]	rr_OperatingExpensesColumnName	Class S
Management Fees (may adjust up or down)	rr_ManagementFeesOverAssets	0.63%
Distribution/Service (12b-1) Fees	rr_DistributionAndService12b1FeesOverAssets	0.25%
Other Expenses	rr_OtherExpensesOverAssets	0.50%
Total Annual Fund Operating Expenses	rr_ExpensesOverAssets	1.38%	[1]
Fee Waiver	rr_FeeWaiverOrReimbursementOverAssets	0.18%	[1]
Total Annual Fund Operating Expenses After Fee Waiver	rr_NetExpensesOverAssets	1.20%	[1]
Expense Example, By Year, Column [Text]	rr_ExpenseExampleByYearColumnName	Class S Shares
1 Year	rr_ExpenseExampleYear01	140
3 Years	rr_ExpenseExampleYear03	437
5 Years	rr_ExpenseExampleYear05	755
10 Years	rr_ExpenseExampleYear10	1,657
Expense Example, No Redemption, By Year, Column [Text]	rr_ExpenseExampleNoRedemptionByYearColumnName	Class S Shares
1 Year	rr_ExpenseExampleNoRedemptionYear01	140
3 Years	rr_ExpenseExampleNoRedemptionYear03	437
5 Years	rr_ExpenseExampleNoRedemptionYear05	755
10 Years	rr_ExpenseExampleNoRedemptionYear10	1,657
Perkins Select Value Fund | Class A, C, S, I, N, T Shares | Class I
Risk/Return:	rr_RiskReturnAbstract
Shareholder Fees Column [Text]	rr_ShareholderFeesColumnName	Class I
Maximum Sales Charge (load) Imposed on Purchases (as a percentage of offering price)	rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice	none
Maximum Deferred Sales Charge (load) (as a percentage of the lower of original purchase price or redemption proceeds)	rr_MaximumDeferredSalesChargeOverOther	none
Operating Expenses Column [Text]	rr_OperatingExpensesColumnName	Class I
Management Fees (may adjust up or down)	rr_ManagementFeesOverAssets	0.63%
Distribution/Service (12b-1) Fees	rr_DistributionAndService12b1FeesOverAssets	none
Other Expenses	rr_OtherExpensesOverAssets	0.24%
Total Annual Fund Operating Expenses	rr_ExpensesOverAssets	0.87%	[1]
Fee Waiver	rr_FeeWaiverOrReimbursementOverAssets	0.17%	[1]
Total Annual Fund Operating Expenses After Fee Waiver	rr_NetExpensesOverAssets	0.70%	[1]
Expense Example, By Year, Column [Text]	rr_ExpenseExampleByYearColumnName	Class I Shares
1 Year	rr_ExpenseExampleYear01	89
3 Years	rr_ExpenseExampleYear03	278
5 Years	rr_ExpenseExampleYear05	482
10 Years	rr_ExpenseExampleYear10	1,073
Expense Example, No Redemption, By Year, Column [Text]	rr_ExpenseExampleNoRedemptionByYearColumnName	Class I Shares
1 Year	rr_ExpenseExampleNoRedemptionYear01	89
3 Years	rr_ExpenseExampleNoRedemptionYear03	278
5 Years	rr_ExpenseExampleNoRedemptionYear05	482
10 Years	rr_ExpenseExampleNoRedemptionYear10	1,073
2012	rr_AnnualReturn2012	12.48%
Bar Chart, Year to Date Return, Date	rr_BarChartYearToDateReturnDate	Sep. 30, 2013
Bar Chart, Year to Date Return	rr_BarChartYearToDateReturn	15.57%
Highest Quarterly Return, Label	rr_HighestQuarterlyReturnLabel	Best Quarter:
Highest Quarterly Return, Date	rr_BarChartHighestQuarterlyReturnDate	Mar. 31, 2012
Highest Quarterly Return	rr_BarChartHighestQuarterlyReturn	11.14%
Lowest Quarterly Return, Label	rr_LowestQuarterlyReturnLabel	Worst Quarter:
Lowest Quarterly Return, Date	rr_BarChartLowestQuarterlyReturnDate	Jun. 30, 2012
Lowest Quarterly Return	rr_BarChartLowestQuarterlyReturn	(4.75%)
Perkins Select Value Fund | Class A, C, S, I, N, T Shares | Class N
Risk/Return:	rr_RiskReturnAbstract
Shareholder Fees Column [Text]	rr_ShareholderFeesColumnName	Class N
Maximum Sales Charge (load) Imposed on Purchases (as a percentage of offering price)	rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice	none
Maximum Deferred Sales Charge (load) (as a percentage of the lower of original purchase price or redemption proceeds)	rr_MaximumDeferredSalesChargeOverOther	none
Operating Expenses Column [Text]	rr_OperatingExpensesColumnName	Class N
Management Fees (may adjust up or down)	rr_ManagementFeesOverAssets	0.63%
Distribution/Service (12b-1) Fees	rr_DistributionAndService12b1FeesOverAssets	none
Other Expenses	rr_OtherExpensesOverAssets	0.24%	[2]
Total Annual Fund Operating Expenses	rr_ExpensesOverAssets	0.87%	[1]
Fee Waiver	rr_FeeWaiverOrReimbursementOverAssets	0.17%	[1]
Total Annual Fund Operating Expenses After Fee Waiver	rr_NetExpensesOverAssets	0.70%	[1]
Expense Example, By Year, Column [Text]	rr_ExpenseExampleByYearColumnName	Class N Shares
1 Year	rr_ExpenseExampleYear01	89
3 Years	rr_ExpenseExampleYear03	278
5 Years	rr_ExpenseExampleYear05	482
10 Years	rr_ExpenseExampleYear10	1,073
Expense Example, No Redemption, By Year, Column [Text]	rr_ExpenseExampleNoRedemptionByYearColumnName	Class N Shares
1 Year	rr_ExpenseExampleNoRedemptionYear01	89
3 Years	rr_ExpenseExampleNoRedemptionYear03	278
5 Years	rr_ExpenseExampleNoRedemptionYear05	482
10 Years	rr_ExpenseExampleNoRedemptionYear10	1,073
Perkins Select Value Fund | Class A, C, S, I, N, T Shares | Class T
Risk/Return:	rr_RiskReturnAbstract
Shareholder Fees Column [Text]	rr_ShareholderFeesColumnName	Class T
Maximum Sales Charge (load) Imposed on Purchases (as a percentage of offering price)	rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice	none
Maximum Deferred Sales Charge (load) (as a percentage of the lower of original purchase price or redemption proceeds)	rr_MaximumDeferredSalesChargeOverOther	none
Operating Expenses Column [Text]	rr_OperatingExpensesColumnName	Class T
Management Fees (may adjust up or down)	rr_ManagementFeesOverAssets	0.63%
Distribution/Service (12b-1) Fees	rr_DistributionAndService12b1FeesOverAssets	none
Other Expenses	rr_OtherExpensesOverAssets	0.48%
Total Annual Fund Operating Expenses	rr_ExpensesOverAssets	1.11%	[1]
Fee Waiver	rr_FeeWaiverOrReimbursementOverAssets	0.16%	[1]
Total Annual Fund Operating Expenses After Fee Waiver	rr_NetExpensesOverAssets	0.95%	[1]
Expense Example, By Year, Column [Text]	rr_ExpenseExampleByYearColumnName	Class T Shares
1 Year	rr_ExpenseExampleYear01	113
3 Years	rr_ExpenseExampleYear03	353
5 Years	rr_ExpenseExampleYear05	612
10 Years	rr_ExpenseExampleYear10	1,352
Expense Example, No Redemption, By Year, Column [Text]	rr_ExpenseExampleNoRedemptionByYearColumnName	Class T Shares
1 Year	rr_ExpenseExampleNoRedemptionYear01	113
3 Years	rr_ExpenseExampleNoRedemptionYear03	353
5 Years	rr_ExpenseExampleNoRedemptionYear05	612
10 Years	rr_ExpenseExampleNoRedemptionYear10	$ 1,352
Perkins Select Value Fund | Class A, C, S, I, N, T Shares | Return Before Taxes | Class A
Risk/Return:	rr_RiskReturnAbstract
Column	rr_AverageAnnualReturnColumnName	Class A Shares
Label	rr_AverageAnnualReturnLabel	Return Before Taxes	[3]
1 Year	rr_AverageAnnualReturnYear01	5.80%
Since Inception	rr_AverageAnnualReturnSinceInception	7.75%
Inception Date	rr_AverageAnnualReturnInceptionDate	Dec. 15, 2011
Perkins Select Value Fund | Class A, C, S, I, N, T Shares | Return Before Taxes | Class C
Risk/Return:	rr_RiskReturnAbstract
Column	rr_AverageAnnualReturnColumnName	Class C Shares
Label	rr_AverageAnnualReturnLabel	Return Before Taxes	[4]
1 Year	rr_AverageAnnualReturnYear01	10.34%
Since Inception	rr_AverageAnnualReturnSinceInception	13.21%
Inception Date	rr_AverageAnnualReturnInceptionDate	Dec. 15, 2011
Perkins Select Value Fund | Class A, C, S, I, N, T Shares | Return Before Taxes | Class S
Risk/Return:	rr_RiskReturnAbstract
Column	rr_AverageAnnualReturnColumnName	Class S Shares
Label	rr_AverageAnnualReturnLabel	Return Before Taxes
1 Year	rr_AverageAnnualReturnYear01	11.89%
Since Inception	rr_AverageAnnualReturnSinceInception	13.71%
Inception Date	rr_AverageAnnualReturnInceptionDate	Dec. 15, 2011
Perkins Select Value Fund | Class A, C, S, I, N, T Shares | Return Before Taxes | Class I
Risk/Return:	rr_RiskReturnAbstract
Column	rr_AverageAnnualReturnColumnName	Class I Shares
Label	rr_AverageAnnualReturnLabel	Return Before Taxes
1 Year	rr_AverageAnnualReturnYear01	12.48%
Since Inception	rr_AverageAnnualReturnSinceInception	14.39%
Inception Date	rr_AverageAnnualReturnInceptionDate	Dec. 15, 2011
Perkins Select Value Fund | Class A, C, S, I, N, T Shares | Return Before Taxes | Class N
Risk/Return:	rr_RiskReturnAbstract
Column	rr_AverageAnnualReturnColumnName	Class N Shares
Label	rr_AverageAnnualReturnLabel	Return Before Taxes
1 Year	rr_AverageAnnualReturnYear01	11.78%
Since Inception	rr_AverageAnnualReturnSinceInception	13.68%
Inception Date	rr_AverageAnnualReturnInceptionDate	Dec. 15, 2011
Perkins Select Value Fund | Class A, C, S, I, N, T Shares | Return Before Taxes | Class T
Risk/Return:	rr_RiskReturnAbstract
Column	rr_AverageAnnualReturnColumnName	Class T Shares
Label	rr_AverageAnnualReturnLabel	Return Before Taxes
1 Year	rr_AverageAnnualReturnYear01	12.32%
Since Inception	rr_AverageAnnualReturnSinceInception	14.13%
Inception Date	rr_AverageAnnualReturnInceptionDate	Dec. 15, 2011
Perkins Select Value Fund | Class A, C, S, I, N, T Shares | Return After Taxes on Distributions | Class I
Risk/Return:	rr_RiskReturnAbstract
Column	rr_AverageAnnualReturnColumnName	Class I Shares
Label	rr_AverageAnnualReturnLabel	Return After Taxes on Distributions
1 Year	rr_AverageAnnualReturnYear01	9.75%
Since Inception	rr_AverageAnnualReturnSinceInception	11.73%
Inception Date	rr_AverageAnnualReturnInceptionDate	Dec. 15, 2011
Perkins Select Value Fund | Class A, C, S, I, N, T Shares | Return After Taxes on Distributions and Sale of Fund Shares | Class I
Risk/Return:	rr_RiskReturnAbstract
Column	rr_AverageAnnualReturnColumnName	Class I Shares
Label	rr_AverageAnnualReturnLabel	Return After Taxes on Distributions and Sale of Fund Shares
1 Year	rr_AverageAnnualReturnYear01	8.30%
Since Inception	rr_AverageAnnualReturnSinceInception	10.79%
Inception Date	rr_AverageAnnualReturnInceptionDate	Dec. 15, 2011
Perkins Select Value Fund | Class A, C, S, I, N, T Shares | Russell 3000® Value Index (reflects no deduction for expenses, fees, or taxes)
Risk/Return:	rr_RiskReturnAbstract
Label	rr_AverageAnnualReturnLabel	Russell 3000® Value Index
1 Year	rr_AverageAnnualReturnYear01	17.55%
Since Inception	rr_AverageAnnualReturnSinceInception	21.33%
Inception Date	rr_AverageAnnualReturnInceptionDate	Dec. 15, 2011

[1] Janus Capital has contractually agreed to waive its investment advisory fee and/or reimburse Fund expenses to the extent that the Fund’s total annual fund operating expenses (excluding any performance adjustments to management fees, the distribution and shareholder servicing fees – applicable to Class A Shares, Class C Shares, and Class S Shares; administrative services fees payable pursuant to the Transfer Agency Agreement; brokerage commissions; interest; dividends; taxes; acquired fund fees and expenses; and extraordinary expenses) exceed 0.77% until at least November 1, 2014. The contractual waiver may be terminated or modified prior to this date only at the discretion of the Board of Trustees.

[2] Other Expenses for Class N Shares are based on the estimated annualized expenses that the Shares expect to incur.

[3] Calculated assuming maximum permitted sales loads.

[4] The one year return is calculated to include the contingent deferred sales charge.

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INTECH U.S. Value Fund | Class A, C, S, I, T Shares

FUND SUMMARY

INTECH U.S. Value Fund

INVESTMENT OBJECTIVE

INTECH U.S. Value Fund seeks long-term growth of capital.

FEES AND EXPENSES OF THE FUND

This table describes the fees and expenses that you may pay if you buy and hold Shares of the Fund. Each share class has different expenses, but represents an investment in the same Fund.

For Class A Shares, you may qualify for sales charge discounts if you and your family invest, or agree to invest in the future, at least $50,000 in the Fund or in other Janus mutual funds. More information about these and other discounts, as well as eligibility requirements for each share class, is available from your financial professional and in the “Purchases” section on page 51 of the Fund’s Prospectus and in the “Purchases” section on page 70 of the Fund’s Statement of Additional Information.

SHAREHOLDER FEES
(fees paid directly from your investment)

Shareholder Fees INTECH U.S. Value Fund Class A, C, S, I, T Shares	Class A	Class C	Class S	Class I	Class T
Shareholder Fees Column [Text]	Class A	Class C	Class S	Class I	Class T
Maximum Sales Charge (load) Imposed on Purchases (as a percentage of offering price)	5.75%	none	none	none	none
Maximum Deferred Sales Charge (load) (as a percentage of the lower of original purchase price or redemption proceeds)	none	1.00%	none	none	none

ANNUAL FUND OPERATING EXPENSES
(expenses that you pay each year as a percentage of the value of your investment)

Annual Fund Operating Expenses INTECH U.S. Value Fund Class A, C, S, I, T Shares	Class A	Class C	Class S	Class I	Class T
Operating Expenses Column [Text]	Class A	Class C	Class S	Class I	Class T
Management Fees	0.50%	0.50%	0.50%	0.50%	0.50%
Distribution/Service (12b-1) Fees	0.25%	1.00%	0.25%	none	none
Other Expenses	0.22%	0.20%	0.41%	0.17%	0.41%
Acquired Fund Fees and Expenses	0.04%	0.04%	0.04%	0.04%	0.04%
Total Annual Fund Operating Expenses	1.01%	1.74%	1.20%	0.71%	0.95%

EXAMPLE:

The Example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds.

The Example assumes that you invest $10,000 in the Fund for the time periods indicated and reinvest all dividends and distributions. The Example also assumes that your investment has a 5% return each year and that the Fund’s operating expenses remain the same. Although your actual costs may be higher or lower, based on these assumptions your costs would be:

If Shares are redeemed:

Expense Example INTECH U.S. Value Fund Class A, C, S, I, T Shares (USD $)	Expense Example, By Year, Column [Text]	1 Year	3 Years	5 Years	10 Years
Class A	Class A Shares	672	878	1,101	1,740
Class C	Class C Shares	277	548	944	2,052
Class S	Class S Shares	122	381	660	1,455
Class I	Class I Shares	73	227	395	883
Class T	Class T Shares	97	303	525	1,166

If Shares are not redeemed:

Expense Example, No Redemption INTECH U.S. Value Fund Class A, C, S, I, T Shares (USD $)	Expense Example, No Redemption, By Year, Column [Text]	1 Year	3 Years	5 Years	10 Years
Class A	Class A Shares	672	878	1,101	1,740
Class C	Class C Shares	177	548	944	2,052
Class S	Class S Shares	122	381	660	1,455
Class I	Class I Shares	73	227	395	883
Class T	Class T Shares	97	303	525	1,166

Portfolio Turnover: 

The Fund pays transaction costs, such as commissions, when it buys and sells securities (or “turns over” its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when Fund shares are held in a taxable account. These costs, which are not reflected in annual fund operating expenses or in the Example, affect the Fund’s performance. During the most recent fiscal year, the Fund’s portfolio turnover rate was 100% of the average value of its portfolio.

PRINCIPAL INVESTMENT STRATEGIES

The Fund invests, under normal circumstances, at least 80% of its net assets in U.S. common stocks from the universe of the Russell 1000^® Value Index, utilizing INTECH’s mathematical investment process. The Russell 1000^® Value Index is an unmanaged index that measures the performance of those Russell 1000 companies with lower price-to-book ratios and lower forecasted growth values.

The Fund pursues its investment objective by applying a mathematical investment process to construct an investment portfolio from the universe of common stocks within its named benchmark index. The goal of this process is to build a portfolio of stocks in a more efficient combination than the named benchmark index. The process seeks to capitalize on the natural volatility of the market by searching for stocks within the index that have high relative volatility (providing the potential for excess returns) but that essentially move in opposite directions or have low correlation to each other (providing the potential for lower relative risk). By constructing the portfolio in this manner and periodically rebalancing the portfolio to maintain potentially more efficient weightings, INTECH’s mathematical investment process seeks to create a portfolio that, over time, produces returns in excess of its named benchmark index with risks similar to that of the benchmark index. The rebalancing techniques used by INTECH may result in a higher portfolio turnover compared to a “buy and hold” fund strategy.

The Fund may lend portfolio securities on a short-term or long-term basis, in an amount equal to up to 1/3 of its total assets as determined at the time of the loan origination.

PRINCIPAL INVESTMENT RISKS

The biggest risk is that the Fund’s returns will vary, and you could lose money. The Fund is designed for long-term investors seeking an equity portfolio, including common stocks. Common stocks tend to be more volatile than many other investment choices.

Value Investing Risk. Because different types of stocks tend to shift in and out of favor depending on market and economic conditions, “value” stocks may perform differently than other types of stocks and from the market as a whole, and can continue to be undervalued by the market for long periods of time.

Market Risk. The value of the Fund’s portfolio may decrease if the value of an individual company or security, or multiple companies or securities, in the portfolio decreases. Further, regardless of how well individual companies or securities perform, the value of the Fund’s portfolio could also decrease if there are deteriorating economic or market conditions. It is important to understand that the value of your investment may fall, sometimes sharply, in response to changes in the market, and you could lose money.

Investment Process Risk. The proprietary mathematical investment process used by INTECH may not achieve the desired results. There is a risk that INTECH’s method of identifying stocks with higher volatility than the named benchmark index or its method of identifying stocks that tend to move in the same or opposite direction relative to each other (correlation) will not result in selecting stocks with continuing volatility or the expected correlation. In INTECH’s history, which spans more than 25 years, INTECH’s mathematical investment process has experienced periods of both underperformance and outperformance relative to an identified benchmark. Even when the proprietary mathematical investment process is working appropriately, INTECH expects that there will be periods of underperformance relative to the benchmark. On an occasional basis, INTECH makes changes to its mathematical investment process. These changes may result in changes to the portfolio, might not provide the intended results, and may adversely impact the Fund’s performance.

Real Estate Securities Risk. The Fund’s performance may be affected by the risks associated with investments in real estate-related companies. The value of real estate-related companies’ securities is sensitive to changes in real estate values and rental income, property taxes, interest rates, tax and regulatory requirements, supply and demand, and the management skill and creditworthiness of the company. Investments in real estate investment trusts (“REITs”) involve the same risks as other real estate investments. In addition, a REIT could fail to qualify for tax-free pass-through of its income under the Internal Revenue Code or fail to maintain its exemption from registration under the Investment Company Act of 1940, as amended, which could produce adverse economic consequences for the REIT and its investors, including the Fund.

Portfolio Turnover Risk. Increased portfolio turnover may result in higher costs, which may have a negative effect on the Fund’s performance. In addition, higher portfolio turnover may result in the acceleration of capital gains and the recognition of greater levels of short-term capital gains, which are taxed at ordinary federal income tax rates when distributed to shareholders.

Securities Lending Risk. The Fund may seek to earn additional income through lending its securities to certain qualified broker-dealers and institutions. There is the risk that when portfolio securities are lent, the securities may not be returned on a timely basis, and the Fund may experience delays and costs in recovering the security or gaining access to the collateral provided to the Fund to collateralize the loan. If the Fund is unable to recover a security on loan, the Fund may use the collateral to purchase replacement securities in the market. There is a risk that the value of the collateral could decrease below the cost of the replacement security by the time the replacement investment is made, resulting in a loss to the Fund.

An investment in the Fund is not a bank deposit and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency.

PERFORMANCE INFORMATION

The following information provides some indication of the risks of investing in the Fund by showing how the Fund’s performance has varied over time. Class I Shares, Class A Shares, Class C Shares, and Class S Shares of the Fund commenced operations on July 6, 2009, after the reorganization of each corresponding class of shares of Janus Adviser INTECH Risk-Managed Value Fund (“JAD predecessor fund”) into each respective share class of the Fund. Class T Shares of the Fund commenced operations on July 6, 2009.

• The performance shown for Class I Shares, Class A Shares, Class C Shares, and Class S Shares for periods prior to July 6, 2009, reflects the historical performance of the JAD predecessor fund’s Class I Shares, Class A Shares, Class C Shares, and Class S Shares prior to the reorganization, calculated using the fees and expenses of each respective share class of the JAD predecessor fund, net of any applicable fee and expense limitations or waivers.
• The performance shown for Class T Shares for periods prior to July 6, 2009, reflects the historical performance of the JAD predecessor fund’s Class I Shares prior to the reorganization, calculated using the fees and expenses of Class T Shares, without the effect of any fee and expense limitations or waivers.

If Class T Shares of the Fund had been available during periods prior to July 6, 2009, the performance shown may have been different. The performance shown for periods following the Fund’s commencement of Class I Shares, Class A Shares, Class C Shares, Class S Shares, and Class T Shares reflects the fees and expenses of each respective share class, net of any applicable fee and expense limitations or waivers.

The bar chart depicts the change in performance from year to year during the periods indicated. The bar chart figures do not include any applicable sales charges that an investor may pay when they buy or sell Class A Shares or Class C Shares of the Fund. If sales charges were included, the returns would be lower. The table compares the Fund’s average annual returns for the periods indicated to a broad-based securities market index. The index is not actively managed and is not available for direct investment. All figures assume reinvestment of dividends and distributions. For certain periods, the Fund’s performance reflects the effect of expense waivers. Without the effect of these expense waivers, the performance shown would have been lower.

The Fund’s past performance (before and after taxes) does not necessarily indicate how it will perform in the future. Updated performance information is available at janus.com/advisor/mutual-funds or by calling 1-877-335-2687.

Annual Total Returns for Class I Shares (calendar year-end)

Best Quarter:  Third Quarter 2009  17.79%          Worst Quarter:  Fourth Quarter 2008  −21.39%

The Fund’s year-to-date return as of the calendar quarter ended September 30, 2013 was 21.91%.

Average Annual Total Returns (periods ended 12/31/12)

Average Annual Total Returns INTECH U.S. Value Fund Class A, C, S, I, T Shares	Column	Label		1 Year	5 Years	Since Inception of Predecessor Fund	Inception Date
Class I Return Before Taxes	Class I Shares	Return Before Taxes		15.64%	0.99%	3.29%	Dec. 30, 2005
Class I Return After Taxes on Distributions	Class I Shares	Return After Taxes on Distributions		15.30%	0.66%	2.89%	Dec. 30, 2005
Class I Return After Taxes on Distributions and Sale of Fund Shares	Class I Shares	Return After Taxes on Distributions and Sale of Fund Shares	[1]	10.63%	0.77%	2.72%	Dec. 30, 2005
Class A Return Before Taxes	Class A Shares	Return Before Taxes	[2]	8.68%	(0.42%)	2.18%	Dec. 30, 2005
Class C Return Before Taxes	Class C Shares	Return Before Taxes	[3]	13.43%	none	2.28%	Dec. 30, 2005
Class S Return Before Taxes	Class S Shares	Return Before Taxes		15.14%	0.54%	2.81%	Dec. 30, 2005
Class T Return Before Taxes	Class T Shares	Return Before Taxes		15.34%	0.67%	2.90%	Dec. 30, 2005
Russell 1000® Value Index (reflects no deduction for expenses, fees, or taxes)		Russell 1000® Value Index		17.51%	0.59%	3.32%	Dec. 30, 2005

After-tax returns are calculated using distributions for the Fund’s Class I Shares for periods following July 6, 2009; and for the JAD predecessor fund’s Class I Shares for periods prior to July 6, 2009. After-tax returns are calculated using the historically highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes. Actual after-tax returns depend on your individual tax situation and may differ from those shown in the preceding table. The after-tax return information shown above does not apply to Fund shares held through a tax-deferred account, such as a 401(k) plan or an IRA.

After-tax returns are only shown for Class I Shares of the Fund. After-tax returns for the other classes of Shares will vary from those shown for Class I Shares due to varying sales charges (as applicable), fees, and expenses among the classes.

[1] If the Fund incurs a loss, which generates a tax benefit, the Return After Taxes on Distributions and Sale of Fund Shares may exceed the Fund's other return figures.

[2] Calculated assuming maximum permitted sales loads.

[3] The one year return is calculated to include the contingent deferred sales charge.

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Janus Diversified Alternatives Fund | Class A, C, S, I, N, T Shares

FUND SUMMARY

Janus Diversified Alternatives Fund

INVESTMENT OBJECTIVE

Janus Diversified Alternatives Fund seeks absolute return with low correlation to stocks and bonds.

FEES AND EXPENSES OF THE FUND

This table describes the fees and expenses that you may pay if you buy and hold Shares of the Fund. Each share class has different expenses, but represents an investment in the same Fund.

For Class A Shares, you may qualify for sales charge discounts if you and your family invest, or agree to invest in the future, at least $50,000 in the Fund or in other Janus mutual funds. More information about these and other discounts, as well as eligibility requirements for each share class, is available from your financial professional and in the “Purchases” section on page 36 of the Fund’s Prospectus and in the “Purchases” section on page 49 of the Fund’s Statement of Additional Information.

SHAREHOLDER FEES
(fees paid directly from your investment)

Shareholder Fees Janus Diversified Alternatives Fund Class A, C, S, I, N, T Shares	Class A	Class C	Class S	Class I	Class N	Class T
Shareholder Fees Column [Text]	Class A	Class C	Class S	Class I	Class N	Class T
Maximum Sales Charge (load) Imposed on Purchases (as a percentage of offering price)	5.75%	none	none	none	none	none
Maximum Deferred Sales Charge (load) (as a percentage of the lower of original purchase price or redemption proceeds)	none	1.00%	none	none	none	none

ANNUAL FUND OPERATING EXPENSES
(expenses that you pay each year as a percentage of the value of your investment)

Annual Fund Operating Expenses Janus Diversified Alternatives Fund Class A, C, S, I, N, T Shares		Class A	Class C	Class S	Class I	Class N	Class T
Operating Expenses Column [Text]		Class A	Class C	Class S	Class I	Class N	Class T
Management Fees of the Fund and the Subsidiary	[1]	1.00%	1.00%	1.00%	1.00%	1.00%	1.00%
Distribution/Service (12b-1) Fees		0.25%	1.00%	0.25%	none	none	none
Other Expenses		0.63%	0.76%	0.76%	0.53%	0.53%	0.76%
Other Expenses of the Fund	[2]	0.61%	0.74%	0.74%	0.51%	0.51%	0.74%
Other Expenses of the Subsidiary		0.02%	0.02%	0.02%	0.02%	0.02%	0.02%
Total Annual Fund Operating Expenses	[3]	1.88%	2.76%	2.01%	1.53%	1.53%	1.76%
Fee Waiver	[3]	0.35%	0.47%	0.24%	0.26%	0.26%	0.24%
Total Annual Fund Operating Expenses After Fee Waiver	[3]	1.53%	2.29%	1.77%	1.27%	1.27%	1.52%

EXAMPLE:

The following Example is based on expenses without waivers. The Example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds.

The Example assumes that you invest $10,000 in the Fund for the time periods indicated and reinvest all dividends and distributions. The Example also assumes that your investment has a 5% return each year and that the Fund’s operating expenses without waivers or recoupments (if applicable) remain the same. Although your actual costs may be higher or lower, based on these assumptions your costs would be:

If Shares are redeemed:

Expense Example Janus Diversified Alternatives Fund Class A, C, S, I, N, T Shares (USD $)	Expense Example, By Year, Column [Text]	1 Year	3 Years	5 Years	10 Years
Class A	Class A Shares	755	1,132	1,533	2,649
Class C	Class C Shares	379	856	1,459	3,090
Class S	Class S Shares	204	630	1,083	2,338
Class I	Class I Shares	156	483	834	1,824
Class N	Class N Shares	156	483	834	1,824
Class T	Class T Shares	179	554	954	2,073

If Shares are not redeemed:

Expense Example, No Redemption Janus Diversified Alternatives Fund Class A, C, S, I, N, T Shares (USD $)	Expense Example, No Redemption, By Year, Column [Text]	1 Year	3 Years	5 Years	10 Years
Class A	Class A Shares	755	1,132	1,533	2,649
Class C	Class C Shares	279	856	1,459	3,090
Class S	Class S Shares	204	630	1,083	2,338
Class I	Class I Shares	156	483	834	1,824
Class N	Class N Shares	156	483	834	1,824
Class T	Class T Shares	179	554	954	2,073

Portfolio Turnover: 

The Fund pays transaction costs, such as commissions, when it buys and sells securities (or “turns over” its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when Fund shares are held in a taxable account. These costs, which are not reflected in annual fund operating expenses or in the Example, affect the Fund’s performance. During the period December 28, 2012 to June 30, 2013, the Fund’s portfolio turnover rate was 38% of the average value of its portfolio.

PRINCIPAL INVESTMENT STRATEGIES

Under normal market conditions, the Fund pursues its investment objective by investing in a diverse group of return drivers, each a type of risk premium (collectively, “risk premia”), across equity, fixed income, commodity, and currency asset classes. Risk premia refers to the return that is expected for assuming a particular market risk. For example, investors expect a higher return in exchange for the perceived risks associated with investing in emerging markets as compared to investing in developed markets. Accordingly, a belief that emerging market equities may outperform developed market equities presents a risk premia opportunity. The Fund seeks to generate returns by identifying and isolating diverse sources of potential risk premia, and combining risk premia into a liquid portfolio that seeks to deliver consistent, absolute returns with a low correlation to the returns generated by investments in stocks and bonds. There is no guarantee that the portfolio will be successful in meeting this objective.

The Fund employs a proprietary multi-factor process to allocate the Fund’s assets across the various risk premia. The process begins with an approximate equal-weighted risk to each risk premium in which the Fund invests, so that no individual risk premium contributes disproportionately to the Fund’s overall risk profile and expected returns over the long term. Next, the Fund applies additional advanced allocation methodologies to the portfolio to tactically adjust the weights of risk premia. The Fund’s portfolio managers generally rebalance risk premia allocations quarterly, but may rebalance such allocations more often from time to time to adjust the Fund’s relative risk premia exposures. The rebalancing techniques used by the Fund’s portfolio managers may result in a higher portfolio turnover rate and related expenses compared to a “buy and hold” fund strategy. The Fund may not utilize all identified risk premia in its investment process at all times. Janus Capital believes that this allocation process may provide better risk adjusted returns than a traditional asset allocation strategy that employs fixed weights for asset classes.

The Fund employs various strategies within the equity, fixed income, commodity, and currency asset classes to identify risk premia and generate returns, including, but not limited to, relative value, momentum, credit, size, roll yield, systematic, and currency carry.

Relative Value – Relative Value investing seeks to capture the spread between a relatively undervalued asset and a more expensive one. For example, one pool of equities often outperforms another pool of equities in a different sector or investment style. Relative value attempts to identify the difference in valuation associated with those assets and favors investments in the relatively undervalued pool to generate return.

Momentum – Momentum investing seeks to capitalize on the expected continuance of trends in the market. For example, if interest rates are increasing, a momentum investor would invest in securities that would generate positive returns if rates continue to increase in the near term.

Credit – Credit investing seeks to invest in fixed-income securities to realize the additional rate of return that corporate debt provides as compared to U.S. Treasuries.

Size – Size investing seeks to generate returns by investing in small capitalization equity securities over large capitalization equity securities. The basis for this strategy is that over time, less liquid equities (small capitalization) will outperform more liquid equities (large capitalization).

Roll Yield – Roll Yield investing seeks to capture returns from favoring certain maturities of commodity futures contracts over others. This strategy typically combines offsetting long and short exposures on various sets of individual commodity futures contracts that have different expiration dates.

Systematic – Systematic investing seeks to invest in one or more asset classes, or a subset of a specific asset class, to generate the associated market return. For example, the Fund may invest a portion of the portfolio in global equities to generate the market returns associated with that type of investment.

Currency Carry – Currency Carry investing seeks to generate returns by investing in higher yielding currencies versus lower yielding currencies. In a carry trade, low interest rate currencies may be sold, and high interest rate currencies may be purchased.

As part of the process to identify and isolate specific risk premia and generate returns, the Fund may have both long and short exposure to securities in which it invests with respect to risk premia. The Fund’s exposure to U.S. and non-U.S. investments, which may include emerging markets, will vary based on perceived investment opportunities and the portfolio managers’ global investment outlook. The Fund will make significant use of derivative instruments, which are instruments that have a value derived from or directly linked to an underlying asset, such as equity securities, fixed-income securities, commodities, currencies, interest rates, or market indices. Derivatives will be used to gain exposure to the various asset classes in which the Fund may invest, to generate returns, for hedging purposes (to offset risks associated with an investment, currency exposure, or market conditions), to adjust currency exposure relative to a benchmark index, and to earn income and enhance returns. The Fund may utilize swaps, including equity, interest rate, currency, and total return swaps. The Fund may utilize options and futures, including forward commodity and currency contracts and U.S. Treasury, interest rate, and market index futures. The Fund’s use of options includes options purchased and sold (written). The Fund’s exposure to derivatives will vary and is not limited to those derivatives listed.

The Fund’s exposure to derivatives will create a leveraging effect on the portfolio where market exposure exceeds amounts invested. This leverage will vary over time and may at times be significant. The Fund may have a substantial cash position due to margin and collateral requirements related to the Fund’s use of derivatives. Such margin and collateral requirements may limit the Fund’s ability to take advantage of other investment opportunities and may negatively affect the Fund’s ability to achieve its investment objective.

The Fund’s equity and fixed-income exposure may be obtained through direct investment in equity and fixed-income securities or through investment in other mutual funds or exchange-traded funds (“ETFs”). The Fund may also utilize exchange-traded notes (“ETNs”). The equity securities in which the Fund invests may involve exposure to common stocks of companies of any size located anywhere in the world, from larger, well-established companies to smaller, emerging growth companies. The fixed-income securities in which the Fund invests may include securities of any maturity and of any credit quality, and may include exposure to government bonds, corporate bonds, convertible bonds, mortgage-backed securities, zero-coupon bonds, and high-yield/high-risk bonds, also known as “junk” bonds. The Fund’s investment in ETFs and ETNs may be used to gain exposure to market indices, a basket of securities, commodities, currencies, or a particular commodity or currency.

The Fund’s exposure to the commodity markets, in whole or in part, may be made through investment in a wholly-owned subsidiary of the Fund organized under the laws of the Cayman Islands (the “Subsidiary”), which is generally subject to the same investment policies and restrictions as the Fund. The Subsidiary will invest in commodity-related derivatives such as futures and swaps, ETNs, and other investments such as cash or U.S. Treasuries which may serve as margin or collateral for the Subsidiary’s commodity-linked derivative positions.

PRINCIPAL INVESTMENT RISKS

The biggest risk is that the Fund’s returns will vary, and you could lose money. The Fund is designed for long-term investors seeking a portfolio which includes exposure to equity (such as stocks or any other security representing an ownership interest), fixed-income (such as bonds, notes, and debentures), commodities, and currency asset classes, and which involves the use of derivatives. Such investments, and derivatives in particular, tend to be more volatile than many other investment choices.

Management Risk. The Fund’s ability to achieve its investment objective depends largely upon the portfolio managers’ successful evaluation of the risks, potential returns, and correlation properties with respect to the various risk premia in which the Fund invests. There is a risk that the returns provided by an individual risk premium may be subject to high volatility and that the portfolio managers’ beliefs about the risk, expected returns and correlation properties of various risk premia may be incorrect. Further, the Fund’s ability to achieve its investment objective also depends on the successful allocation of the Fund’s assets among various risk premia and asset classes, and you could lose money on your investment in the Fund as a result of these allocations. There is also a risk that the Fund’s investments will correlate with the performance of stocks and bonds to a greater degree than anticipated, and the Fund will not meet its investment objective. Finally, Janus Capital does not have prior experience managing a risk premia investment strategy, and there is no guarantee that the investment techniques and analysis used by the Fund’s portfolio managers will produce the desired results.

Market Risk. The value of the Fund’s portfolio may decrease if the value of an individual investment, or multiple investments, in the portfolio decreases at the same time. Further, while the Fund’s goal is to produce returns that have a low correlation to the stock and bond markets, you should understand that regardless of how well the Fund’s individual investments perform, the value of the Fund’s portfolio could also decrease if there are deteriorating economic or market conditions. The value of your investment in the Fund may fall, sometimes sharply, in response to changes in the market, and you could lose money. Because the Fund seeks to produce returns that have a low correlation to the returns generated by the stock and bond markets, the Fund may underperform these markets when these markets rise sharply or experience prolonged periods of outperformance. Additionally, the Fund’s performance may be negatively affected during prolonged periods when the returns provided by the risk premia are consistently low.

Derivatives Risk. Derivatives can be highly volatile and involve risks in addition to the risks of the underlying referenced securities. Gains or losses from a derivative investment can be substantially greater than the derivative’s original cost, and can therefore involve leverage. Leverage may cause the Fund to be more volatile than if it had not used leverage. Derivatives can be complex instruments and may involve analysis that differs from that required for other investment types used by the Fund. If the value of a derivative does not correlate well with the particular market or other asset class to which the derivative is intended to provide exposure, the derivative may not produce the anticipated result. Derivatives can also reduce the opportunity for gain or result in losses by offsetting positive returns in other investments. Derivatives can be less liquid than other types of investments and entail the risk that the counterparty will default on its payment obligations. If the counterparty to a derivative transaction defaults, the Fund would risk the loss of the net amount of the payments that it contractually is entitled to receive. To the extent the Fund enters into short derivative positions, the Fund may be exposed to risks similar to those associated with short sales, including the risk that the Fund’s losses are theoretically unlimited.

Leverage Risk. Engaging in transactions using leverage or those having a leveraging effect subjects the Fund to certain risks. Leverage can magnify the effect of any gains or losses, causing the Fund to be more volatile than if it had not been leveraged. Certain commodity-linked derivative investments may subject the Fund to leveraged market exposure to commodities. In addition, the Fund’s assets that are used as collateral to secure short sale transactions may decrease in value while the short positions are outstanding, which may force the Fund to use its other assets to increase collateral. There is no assurance that a leveraging strategy will be successful.

Short Sales Risk. Short sales are speculative transactions and involve special risks, including a greater reliance on the portfolio managers’ ability to accurately anticipate the future value of a security. The Fund will suffer a loss if it sells a security short and the value of the security rises rather than falls. The Fund’s losses are potentially unlimited in a short sale transaction. The use of short sales may also cause the Fund to have higher expenses than those of other funds. In addition, due to the investment process of long and short positions, the Fund may be subject to additional transaction costs that may lower the Fund’s returns. The Fund’s use of short sales may also have a leveraging effect on the Fund’s portfolio.

Counterparty Risk. Certain derivative and “over-the-counter” instruments, such as swaps and forwards, are subject to the risk that the other party to a contract will not fulfill its contractual obligations.

Commodity-Linked Investments Risk. The Fund may invest, directly or indirectly, in various commodity-linked investments that provide exposure to the commodities markets. Such exposure may subject the Fund to greater volatility than investments in traditional securities. The value of a given commodity-linked derivative investment typically is based upon the price movements of a physical commodity (such as heating oil, livestock, or agricultural products), a commodity futures contract or commodity index, or some other readily measurable economic variable. The value of commodity-linked derivative instruments may therefore be affected by changes in overall market movements, volatility of the underlying benchmark, changes in interest rates, or other factors affecting a particular industry or commodity such as drought, floods, weather, livestock disease, embargoes, tariffs, and international economic, political, and regulatory developments.

Subsidiary Risk. By investing in the Subsidiary, the Fund will be indirectly exposed to the risks associated with the Subsidiary’s investments, which are generally similar to those that are permitted to be held by the Fund. The Subsidiary is not registered under the Investment Company Act of 1940, as amended (the “1940 Act”), and is not subject to all of the provisions of the 1940 Act. The Internal Revenue Service (“IRS”) has previously issued a number of private letter rulings to mutual funds (but not the Fund), in which it ruled that income from a fund’s investment in a wholly-owned foreign subsidiary that invests in commodity-linked derivatives, such as the Subsidiary, constitutes qualifying income. The IRS has suspended issuance of any further private letter rulings pending a review of its position. A change in the IRS’ position or changes in the laws of the United States and/or the Cayman Islands could result in the inability of the Fund and/or the Subsidiary to operate as described in the Fund’s Prospectus and the Statement of Additional Information. Such changes could adversely affect the Fund’s ability to meet its investment objective and jeopardize the Fund’s status as a regulated investment company under the U.S. tax code, which in turn may subject the Fund to higher tax rates and/or penalties.

Foreign Exposure Risk. The Fund normally has exposure to foreign markets as a result of its investments in foreign securities, including investments in emerging markets, which can be more volatile than the U.S. markets. As a result, its returns and net asset value may be affected to a large degree by fluctuations in currency exchange rates or political or economic conditions in a particular country. In some foreign markets, there may not be protection against failure by other parties to complete transactions. It may not be possible for the Fund to repatriate capital, dividends, interest, and other income from a particular country or governmental entity. In addition, a market swing in one or more countries or regions where the Fund has invested a significant amount of its assets may have a greater effect on the Fund’s performance than it would in a more geographically diversified portfolio. To the extent the Fund invests in foreign debt securities, such investments are sensitive to changes in interest rates. Additionally, investments in securities of foreign governments involve the risk that a foreign government may not be willing or able to pay interest or repay principal when due. The Fund’s exposure to emerging market countries may involve risks greater than, or in addition to, the risks of investing in more developed countries.

Eurozone Risk. A number of countries in the European Union (“EU”) have experienced severe economic and financial difficulties. As a result, financial markets in the EU have been subject to extreme volatility and declines in asset values and liquidity. Responses to these financial problems by European governments, central banks, and others, including austerity measures and reforms, may not work, may result in social unrest, and may limit future growth and economic recovery or have other unintended consequences. Further defaults or restructurings by governments and others of their debt could have additional adverse effects on economies, financial markets, and asset valuations around the world. To the extent that the Fund has exposure to European markets or to transactions tied to the value of the euro, these events could negatively affect the value and liquidity of the Fund’s investments.

Emerging Markets Risk. The risks of foreign investing mentioned above are heightened when investing in emerging markets. Emerging markets securities involve a number of additional risks, which may result from less government supervision and regulation of business and industry practices (including the potential lack of strict finance and accounting controls and standards), stock exchanges, brokers, and listed companies, making these investments potentially more volatile in price and less liquid than investments in developed securities markets, resulting in greater risk to investors. There is a risk in developing countries that a future economic or political crisis could lead to price controls, forced mergers of companies, expropriation or confiscatory taxation, imposition or enforcement of foreign ownership limits, seizure, nationalization, or creation of government monopolies, any of which may have a detrimental effect on the Fund’s investments. In addition, the Fund’s investments may be denominated in foreign currencies and therefore, changes in the value of a country’s currency compared to the U.S. dollar may affect the value of the Fund’s investments. To the extent that the Fund invests a significant portion of its assets in the securities of issuers in or companies of a single country or region, it is more likely to be impacted by events or conditions affecting that country or region, which could have a negative impact on the Fund’s performance. Some of the risks of investing directly in foreign and emerging market securities may be reduced when the Fund invests indirectly in foreign securities through various other investment vehicles including derivatives, which also involve other risks.

Growth Securities Risk. The Fund invests in companies after assessing their growth potential. Securities of companies perceived to be “growth” companies may be more volatile than other stocks and may involve special risks. If the portfolio managers’ perception of a company’s growth potential is not realized, the securities purchased may not perform as expected, reducing the Fund’s returns. In addition, because different types of stocks tend to shift in and out of favor depending on market and economic conditions, “growth” stocks may perform differently from the market as a whole and other types of securities.

Fixed-Income Securities Risk. The Fund invests in a variety of fixed-income securities. Typically, the values of fixed-income securities change inversely with prevailing interest rates. Therefore, a fundamental risk of fixed-income securities is interest rate risk, which is the risk that the value of such securities will generally decline as prevailing interest rates rise, which may cause the Fund’s net asset value to likewise decrease. How specific fixed-income securities may react to changes in interest rates will depend on the specific characteristics of each security. Fixed-income securities are also subject to credit risk, prepayment risk, valuation risk, and liquidity risk. Credit risk is the risk that the credit strength of an issuer of a fixed-income security will weaken and/or that the issuer will be unable to make timely principal and interest payments and that the security may go into default. Prepayment risk is the risk that during periods of falling interest rates, certain fixed-income securities with higher interest rates, such as mortgage- and asset-backed securities, may be prepaid by their issuers thereby reducing the amount of interest payments. Valuation risk is the risk that one or more of the fixed-income securities in which the Fund invests are priced differently than the value realized upon such security’s sale. In times of market instability, valuation may be more difficult. Liquidity risk is the risk that fixed-income securities may be difficult or impossible to sell at the time that the portfolio managers would like or at the price the portfolio managers believe the security is currently worth.

Mortgage-Backed Securities Risk. Mortgage-backed securities are classified generally as either commercial mortgage-backed securities or residential mortgage-backed securities, each of which is subject to certain specific risks. Mortgage-backed securities tend to be more sensitive to changes in interest rates than other types of debt securities. Investments in mortgage-backed securities are subject to both extension risk, where borrowers extend the duration of their mortgages in times of rising interest rates, and prepayment risk, where borrowers pay off their mortgages sooner than expected in times of declining interest rates. These risks may reduce the Fund’s returns. In addition, investments in mortgage-backed securities, including those comprised of subprime mortgages, may be subject to a higher degree of credit risk, valuation risk, and liquidity risk than various other types of fixed-income securities.

Currency Risk. The Fund’s investments and strategies will involve exposure to foreign currencies. Currency risk is the risk that changes in the exchange rate between currencies will adversely affect the value (in U.S. dollar terms) of an investment. As long as the Fund holds a foreign security, its value will be affected by the value of the local currency relative to the U.S. dollar. When the Fund sells a foreign currency denominated security, its value may be worth less in U.S. dollars even if the security increases in value in its home country. U.S. dollar-denominated securities of foreign issuers may also be affected by currency risk, as the value of these securities may also be affected by changes in the issuer’s local currency. Additionally, and as a result of the Fund’s use of currency investment strategies, the Fund’s net currency positions may expose the Fund to losses independent of any securities positions.

High-Yield/High-Risk Bond Risk. High-yield/high-risk bonds may be more sensitive than other types of bonds to economic changes, political changes, or adverse developments specific to the company that issued the bond, which may adversely affect their value.

Portfolio Turnover Risk. Increased portfolio turnover may result in higher costs, which may have a negative effect on the Fund’s performance. In addition, higher portfolio turnover may result in the acceleration of capital gains and the recognition of greater levels of short-term capital gains, which are taxed at ordinary federal income tax rates when distributed to shareholders.

Exchange-Traded Funds Risk. The Fund may invest in ETFs, which are typically open-end investment companies that are traded on a national securities exchange. ETFs typically incur fees, such as investment advisory fees and other operating expenses that are separate from those of the Fund, which will be indirectly paid by the Fund. As a result, the cost of investing in the Fund may be higher than the cost of investing directly in ETFs and may be higher than other mutual funds that invest directly in stocks and bonds. Further, the price movement of an ETF may fluctuate against the underlying securities or commodities it tracks and may result in a loss. Because the value of ETF shares depends on the demand in the market, the Fund may not be able to purchase or sell an ETF at the most optimal time, which could adversely affect the Fund’s performance.

The ETFs in which the Fund invests are subject to specific risks, depending on the investment strategy of the ETF. In turn, the Fund will be subject to substantially the same risks as those associated with direct exposure to the securities or commodities held by the ETF. Because the Fund may invest in a broad range of ETFs, such risks may include, but are not limited to, leverage risk, foreign exposure risk, fixed-income risk, and commodity-linked investments risk.

Exchange-Traded Notes Risk. The Fund may invest in ETNs, which are debt securities whose returns are linked to a particular index. ETNs are typically linked to the performance of a commodities index that reflects the potential return on unleveraged investments in futures contracts of physical commodities, plus a specified rate of interest that could be earned on cash collateral. ETNs are subject to credit risk and counterparty risk. The value of an ETN may vary and may be influenced by time to maturity, level of supply and demand for the ETN, volatility and lack of liquidity in underlying commodities markets, changes in the applicable interest rates, changes in the issuer’s credit rating, and economic, legal, political, or geographic events that affect the referenced commodity. When the Fund invests in ETNs it will bear its proportionate share of any fees and expenses borne by the ETN. There may be restrictions on the Fund’s right to redeem its investment in an ETN, which is meant to be held until maturity. The Fund’s decision to sell its ETN holdings may be limited by the availability of a secondary market.

Nondiversification Risk. Although the Fund seeks diverse sources of potential return or risk premia, the Fund is classified as nondiversified under the 1940 Act. This gives the Fund’s portfolio managers more flexibility to hold larger positions in a smaller number of securities. As a result, an increase or decrease in the value of a single security held by the Fund may have a greater impact on the Fund’s net asset value and total return.

An investment in the Fund is not a bank deposit and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency.

PERFORMANCE INFORMATION

The Fund does not have a full calendar year of operations. Performance information for certain periods is included in the Fund’s first annual and/or semiannual report.

[1] The Fund may invest in commodity-linked investments through a wholly-owned subsidiary of the Fund that invests in commodity-linked investments. Janus Capital has contractually agreed that to the extent the Fund invests in the subsidiary, it shall not collect advisory fees from the Fund in an amount equal to the fee it collects from the subsidiary. The management fee waiver arrangement may not be discontinued by Janus Capital as long as its contract with the subsidiary is in place.

[2] Other Expenses are based on the estimated expenses that the Fund expects to incur.

[3] Janus Capital has contractually agreed to waive its investment advisory fee and/or reimburse Fund expenses to the extent that the Fund's total annual fund operating expenses, which include the other expenses of the subsidiary shown above (excluding the distribution and shareholder servicing fees – applicable to Class A Shares, Class C Shares, and Class S Shares; administrative services fees payable pursuant to the Transfer Agency Agreement; brokerage commissions; interest; dividends; taxes; acquired fund fees and expenses; and extraordinary expenses) exceed 1.25% until at least November 1, 2014. The contractual waiver may be terminated or modified prior to this date only at the discretion of the Board of Trustees. For a period of three years subsequent to the Fund's commencement of operations (December 28, 2012) or until the Fund's assets exceed the first breakpoint in the investment advisory fee schedule, whichever occurs first, Janus Capital may recover from the Fund fees and expenses previously waived or reimbursed, which could then be considered a deferral, if the Fund's expense ratio, including recovered expenses, falls below the expense limit.

XML

Label	Element	Value
Risk/Return:	rr_RiskReturnAbstract
Registrant Name	dei_EntityRegistrantName	JANUS INVESTMENT FUND
Prospectus Date	rr_ProspectusDate	Oct. 28, 2013
Janus High-Yield Fund | Class A, C, S, I, N, R, T Shares
Risk/Return:	rr_RiskReturnAbstract
Risk/Return [Heading]	rr_RiskReturnHeading	FUND SUMMARY Janus High-Yield Fund
Objective [Heading]	rr_ObjectiveHeading	INVESTMENT OBJECTIVES
Objective, Primary [Text Block]	rr_ObjectivePrimaryTextBlock	Janus High-Yield Fund seeks to obtain high current income.
Objective, Secondary [Text Block]	rr_ObjectiveSecondaryTextBlock	Capital appreciation is a secondary investment objective when consistent with its primary investment objective.
Expense [Heading]	rr_ExpenseHeading	FEES AND EXPENSES OF THE FUND
Expense Narrative [Text Block]	rr_ExpenseNarrativeTextBlock	This table describes the fees and expenses that you may pay if you buy and hold Shares of the Fund. Each share class has different expenses, but represents an investment in the same Fund.
Shareholder Fees Caption [Text]	rr_ShareholderFeesCaption	SHAREHOLDER FEES (fees paid directly from your investment)
Operating Expenses Caption [Text]	rr_OperatingExpensesCaption	ANNUAL FUND OPERATING EXPENSES (expenses that you pay each year as a percentage of the value of your investment)
Portfolio Turnover [Heading]	rr_PortfolioTurnoverHeading	Portfolio Turnover:
Portfolio Turnover [Text Block]	rr_PortfolioTurnoverTextBlock	The Fund pays transaction costs, such as commissions, when it buys and sells securities (or “turns over” its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when Fund shares are held in a taxable account. These costs, which are not reflected in annual fund operating expenses or in the Example, affect the Fund’s performance. During the most recent fiscal year, the Fund’s portfolio turnover rate was 93% of the average value of its portfolio.
Portfolio Turnover, Rate	rr_PortfolioTurnoverRate	93.00%
Expense Breakpoint Discounts [Text]	rr_ExpenseBreakpointDiscounts	For Class A Shares, you may qualify for sales charge discounts if you and your family invest, or agree to invest in the future, at least $50,000 in the Fund or in other Janus mutual funds. More information about these and other discounts, as well as eligibility requirements for each share class, is available from your financial professional and in the “Purchases” section on page 64 of the Fund’s Prospectus and in the “Purchases” section on page 70 of the Fund’s Statement of Additional Information.
Expense Breakpoint, Minimum Investment Required [Amount]	rr_ExpenseBreakpointMinimumInvestmentRequiredAmount	$ 50,000
Expense Example [Heading]	rr_ExpenseExampleHeading	EXAMPLE:
Expense Example by Year [Heading]	rr_ExpenseExampleByYearHeading	The Example assumes that you invest $10,000 in the Fund for the time periods indicated and reinvest all dividends and distributions. The Example also assumes that your investment has a 5% return each year and that the Fund’s operating expenses remain the same. Although your actual costs may be higher or lower, based on these assumptions your costs would be:
Expense Example Narrative [Text Block]	rr_ExpenseExampleNarrativeTextBlock	The Example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds.
Expense Example by, Year, Caption [Text]	rr_ExpenseExampleByYearCaption	If Shares are redeemed:
Expense Example, No Redemption, By Year, Caption [Text]	rr_ExpenseExampleNoRedemptionByYearCaption	If Shares are not redeemed:
Strategy [Heading]	rr_StrategyHeading	PRINCIPAL INVESTMENT STRATEGIES
Strategy Narrative [Text Block]	rr_StrategyNarrativeTextBlock	The Fund pursues its investment objectives by investing, under normal circumstances, at least 80% of its net assets in high-yield/high-risk securities rated below investment grade. Securities rated below investment grade may include their unrated equivalents or other high-yielding securities the portfolio managers believe offer attractive risk/return characteristics. The Fund may at times invest all of its assets in such securities. The Fund may also invest in bank loans, money market instruments, and foreign debt securities (which may include investments in emerging markets). Due to the nature of securities in which the Fund invests, it may have relatively high portfolio turnover compared to other funds. In addition, the Fund may invest its assets in derivatives, which are instruments that have a value derived from, or directly linked to, an underlying asset, such as equity securities, fixed-income securities, commodities, currencies, interest rates, or market indices. In particular, the Fund may use interest rate futures to manage portfolio risk. The Fund’s exposure to derivatives will vary. For purposes of meeting its 80% investment policy, the Fund may include derivatives that have characteristics similar to the securities in which the Fund may directly invest. In addition to considering economic factors such as the effect of interest rates on the Fund’s investments, the portfolio managers apply a “bottom up” approach in choosing investments. This means that the portfolio managers look at income-producing securities one at a time to determine if a security is an attractive investment opportunity and if it is consistent with the Fund’s investment policies. The Fund may lend portfolio securities on a short-term or long-term basis, in an amount equal to up to 1/3 of its total assets as determined at the time of the loan origination.
Risk [Heading]	rr_RiskHeading	PRINCIPAL INVESTMENT RISKS
Risk Narrative [Text Block]	rr_RiskNarrativeTextBlock	Although the Fund may be less volatile than funds that invest most of their assets in common stocks, the Fund’s returns and yields will vary, and you could lose money. Fixed-Income Securities Risk. The Fund invests in a variety of fixed-income securities. Typically, the values of fixed-income securities change inversely with prevailing interest rates. Therefore, a fundamental risk of fixed-income securities is interest rate risk, which is the risk that the value of such securities will generally decline as prevailing interest rates rise, which may cause the Fund’s net asset value to likewise decrease. How specific fixed-income securities may react to changes in interest rates will depend on the specific characteristics of each security. Fixed-income securities are also subject to credit risk, prepayment risk, valuation risk, and liquidity risk. Credit risk is the risk that the credit strength of an issuer of a fixed-income security will weaken and/or that the issuer will be unable to make timely principal and interest payments and that the security may go into default. Prepayment risk is the risk that during periods of falling interest rates, certain fixed-income securities with higher interest rates, such as mortgage- and asset-backed securities, may be prepaid by their issuers thereby reducing the amount of interest payments. Valuation risk is the risk that one or more of the fixed-income securities in which the Fund invests are priced differently than the value realized upon such security’s sale. In times of market instability, valuation may be more difficult. Liquidity risk is the risk that fixed-income securities may be difficult or impossible to sell at the time that the portfolio managers would like or at the price the portfolio managers believe the security is currently worth. High-Yield/High-Risk Bond Risk. The Fund may invest without limit in higher-yielding/higher-risk bonds, also known as “junk” bonds. High-yield/high-risk bonds may be more sensitive than other types of bonds to economic changes, political changes, or adverse developments specific to the company that issued the bond, which may adversely affect their value. Bank Loan Risk. Bank loans are obligations of companies or other entities entered into in connection with recapitalizations, acquisitions, and refinancings. The Fund’s investments in bank loans are generally acquired as a participation interest in, or assignment of, loans originated by a lender or other financial institution. These investments may include institutionally-traded floating and fixed-rate debt securities. Participation interests and assignments involve credit, interest rate, and liquidity risk. In addition, the bank loans underlying these securities often involve borrowers with low credit ratings whose financial conditions are troubled or uncertain, including companies that are highly leveraged or in bankruptcy proceedings. Foreign Exposure Risk. The Fund may have exposure to foreign markets as a result of its investments in foreign securities, including investments in emerging markets, which can be more volatile than the U.S. markets. As a result, its returns and net asset value may be affected to a large degree by fluctuations in currency exchange rates or political or economic conditions in a particular country. In some foreign markets, there may not be protection against failure by other parties to complete transactions. It may not be possible for the Fund to repatriate capital, dividends, interest, and other income from a particular country or governmental entity. In addition, a market swing in one or more countries or regions where the Fund has invested a significant amount of its assets may have a greater effect on the Fund’s performance than it would in a more geographically diversified portfolio. To the extent the Fund invests in foreign debt securities, such investments are sensitive to changes in interest rates. Additionally, investments in securities of foreign governments involve the risk that a foreign government may not be willing or able to pay interest or repay principal when due. The Fund’s investments in emerging market countries may involve risks greater than, or in addition to, the risks of investing in more developed countries. Portfolio Turnover Risk. Increased portfolio turnover may result in higher costs, which may have a negative effect on the Fund’s performance. In addition, higher portfolio turnover may result in the acceleration of capital gains and the recognition of greater levels of short-term capital gains, which are taxed at ordinary federal income tax rates when distributed to shareholders. Derivatives Risk. Derivatives can be highly volatile and involve risks in addition to the risks of the underlying referenced securities. Gains or losses from a derivative investment can be substantially greater than the derivative’s original cost, and can therefore involve leverage. Leverage may cause the Fund to be more volatile than if it had not used leverage. Derivatives can be less liquid than other types of investments and entail the risk that the counterparty will default on its payment obligations. Securities Lending Risk. The Fund may seek to earn additional income through lending its securities to certain qualified broker-dealers and institutions. There is the risk that when portfolio securities are lent, the securities may not be returned on a timely basis, and the Fund may experience delays and costs in recovering the security or gaining access to the collateral provided to the Fund to collateralize the loan. If the Fund is unable to recover a security on loan, the Fund may use the collateral to purchase replacement securities in the market. There is a risk that the value of the collateral could decrease below the cost of the replacement security by the time the replacement investment is made, resulting in a loss to the Fund. An investment in the Fund is not a bank deposit and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency.
Risk Lose Money [Text]	rr_RiskLoseMoney	Although the Fund may be less volatile than funds that invest most of their assets in common stocks, the Fund’s returns and yields will vary, and you could lose money.
Risk Not Insured Depository Institution [Text]	rr_RiskNotInsuredDepositoryInstitution	An investment in the Fund is not a bank deposit and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency.
Bar Chart and Performance Table [Heading]	rr_BarChartAndPerformanceTableHeading	PERFORMANCE INFORMATION
Performance Narrative [Text Block]	rr_PerformanceNarrativeTextBlock	The following information provides some indication of the risks of investing in the Fund by showing how the Fund’s performance has varied over time. Class T Shares (formerly named Class J Shares, the initial share class) of the Fund commenced operations with the Fund’s inception. Class A Shares, Class C Shares, Class S Shares, Class I Shares, and Class R Shares of the Fund commenced operations on July 6, 2009. Class N Shares of the Fund commenced operations on May 31, 2012. The performance shown for Class T Shares is calculated using the fees and expenses of Class T Shares in effect during the periods shown, net of any applicable fee and expense limitations or waivers. The performance shown for Class A Shares, Class C Shares, Class S Shares, and Class R Shares for periods prior to July 6, 2009, reflects the performance of the Fund’s former Class J Shares, calculated using the fees and expenses of each respective share class, without the effect of any fee and expense limitations or waivers. The performance shown for Class I Shares for periods prior to July 6, 2009, reflects the performance of the Fund’s former Class J Shares, calculated using the fees and expenses of Class J Shares, net of any applicable fee and expense limitations or waivers. The performance shown for Class N Shares for periods prior to May 31, 2012, reflects the performance of the Fund’s Class T Shares, calculated using the fees and expenses of Class T Shares, net of any applicable fee and expense limitations or waivers. If Class A Shares, Class C Shares, Class S Shares, Class I Shares, and Class R Shares of the Fund had been available during periods prior to July 6, 2009, or Class N Shares of the Fund had been available during periods prior to May 31, 2012, the performance shown for each respective share class may have been different. The performance shown for periods following the Fund’s commencement of Class A Shares, Class C Shares, Class S Shares, Class I Shares, Class N Shares, and Class R Shares reflects the fees and expenses of each respective share class, net of any applicable fee and expense limitations or waivers. The bar chart depicts the change in performance from year to year during the periods indicated. The bar chart figures do not include any applicable sales charges that an investor may pay when they buy or sell Class A Shares or Class C Shares of the Fund. If sales charges were included, the returns would be lower. The table compares the Fund’s average annual returns for the periods indicated to a broad-based securities market index. The index is not actively managed and is not available for direct investment. All figures assume reinvestment of dividends and distributions. For certain periods, the Fund’s performance reflects the effect of expense waivers. Without the effect of these expense waivers, the performance shown would have been lower. The Fund’s past performance (before and after taxes) does not necessarily indicate how it will perform in the future. Updated performance information is available at janus.com/advisor/mutual-funds or by calling 1-877-335-2687.
Performance Information Illustrates Variability of Returns [Text]	rr_PerformanceInformationIllustratesVariabilityOfReturns	The following information provides some indication of the risks of investing in the Fund by showing how the Fund’s performance has varied over time. The bar chart depicts the change in performance from year to year during the periods indicated.
Performance Additional Market Index [Text]	rr_PerformanceAdditionalMarketIndex	The table compares the Fund’s average annual returns for the periods indicated to a broad-based securities market index. The index is not actively managed and is not available for direct investment. All figures assume reinvestment of dividends and distributions.
Performance Availability Phone [Text]	rr_PerformanceAvailabilityPhone	1-877-335-2687
Performance Availability Website Address [Text]	rr_PerformanceAvailabilityWebSiteAddress	janus.com/advisor/mutual-funds
Performance Past Does Not Indicate Future [Text]	rr_PerformancePastDoesNotIndicateFuture	The Fund’s past performance (before and after taxes) does not necessarily indicate how it will perform in the future.
Bar Chart [Heading]	rr_BarChartHeading	Annual Total Returns for Class T Shares (calendar year-end)
Bar Chart Does Not Reflect Sales Loads [Text]	rr_BarChartDoesNotReflectSalesLoads	The bar chart figures do not include any applicable sales charges that an investor may pay when they buy or sell Class A Shares or Class C Shares of the Fund. If sales charges were included, the returns would be lower.
Bar Chart Closing [Text Block]	rr_BarChartClosingTextBlock	Best Quarter:  Second Quarter 2009  14.93%          Worst Quarter:  Fourth Quarter 2008  −12.96%
Year to Date Return, Label	rr_YearToDateReturnLabel	The Fund’s year-to-date return as of the calendar quarter ended September 30, 2013 was 3.54%.
Performance Table Heading	rr_PerformanceTableHeading	Average Annual Total Returns (periods ended 12/31/12)
Performance Table Uses Highest Federal Rate	rr_PerformanceTableUsesHighestFederalRate	After-tax returns are calculated using the historically highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes.
Performance Table Not Relevant to Tax Deferred	rr_PerformanceTableNotRelevantToTaxDeferred	Actual after-tax returns depend on your individual tax situation and may differ from those shown in the preceding table. The after-tax return information shown above does not apply to Fund shares held through a tax-deferred account, such as a 401(k) plan or an IRA.
Performance Table One Class of after Tax Shown [Text]	rr_PerformanceTableOneClassOfAfterTaxShown	After-tax returns are only shown for Class T Shares of the Fund. After-tax returns for the other classes of Shares will vary from those shown for Class T Shares due to varying sales charges (as applicable), fees, and expenses among the classes.
Performance Table Explanation after Tax Higher	rr_PerformanceTableExplanationAfterTaxHigher	If the Fund incurs a loss, which generates a tax benefit, the Return After Taxes on Distributions and Sale of Fund Shares may exceed the Fund’s other return figures.
Performance Table Narrative	rr_PerformanceTableNarrativeTextBlock	After-tax returns are calculated using distributions for the Fund’s Class T Shares (formerly named Class J Shares, the initial share class). After-tax returns are calculated using the historically highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes. Actual after-tax returns depend on your individual tax situation and may differ from those shown in the preceding table. The after-tax return information shown above does not apply to Fund shares held through a tax-deferred account, such as a 401(k) plan or an IRA. After-tax returns are only shown for Class T Shares of the Fund. After-tax returns for the other classes of Shares will vary from those shown for Class T Shares due to varying sales charges (as applicable), fees, and expenses among the classes.
Performance Table Closing [Text Block]	rr_PerformanceTableClosingTextBlock	Updated performance information is available at janus.com/advisor/mutual-funds or by calling 1-877-335-2687.
Janus High-Yield Fund | Class A, C, S, I, N, R, T Shares | Class A
Risk/Return:	rr_RiskReturnAbstract
Shareholder Fees Column [Text]	rr_ShareholderFeesColumnName	Class A
Maximum Sales Charge (load) Imposed on Purchases (as a percentage of offering price)	rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice	4.75%
Maximum Deferred Sales Charge (load) (as a percentage of the lower of original purchase price or redemption proceeds)	rr_MaximumDeferredSalesChargeOverOther	none
Operating Expenses Column [Text]	rr_OperatingExpensesColumnName	Class A
Management Fees	rr_ManagementFeesOverAssets	0.56%
Distribution/Service (12b-1) Fees	rr_DistributionAndService12b1FeesOverAssets	0.25%
Other Expenses	rr_OtherExpensesOverAssets	0.16%
Total Annual Fund Operating Expenses	rr_ExpensesOverAssets	0.97%
Expense Example, By Year, Column [Text]	rr_ExpenseExampleByYearColumnName	Class A Shares
1 Year	rr_ExpenseExampleYear01	569
3 Years	rr_ExpenseExampleYear03	769
5 Years	rr_ExpenseExampleYear05	986
10 Years	rr_ExpenseExampleYear10	1,608
Expense Example, No Redemption, By Year, Column [Text]	rr_ExpenseExampleNoRedemptionByYearColumnName	Class A Shares
1 Year	rr_ExpenseExampleNoRedemptionYear01	569
3 Years	rr_ExpenseExampleNoRedemptionYear03	769
5 Years	rr_ExpenseExampleNoRedemptionYear05	986
10 Years	rr_ExpenseExampleNoRedemptionYear10	1,608
Janus High-Yield Fund | Class A, C, S, I, N, R, T Shares | Class C
Risk/Return:	rr_RiskReturnAbstract
Shareholder Fees Column [Text]	rr_ShareholderFeesColumnName	Class C
Maximum Sales Charge (load) Imposed on Purchases (as a percentage of offering price)	rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice	none
Maximum Deferred Sales Charge (load) (as a percentage of the lower of original purchase price or redemption proceeds)	rr_MaximumDeferredSalesChargeOverOther	1.00%
Operating Expenses Column [Text]	rr_OperatingExpensesColumnName	Class C
Management Fees	rr_ManagementFeesOverAssets	0.56%
Distribution/Service (12b-1) Fees	rr_DistributionAndService12b1FeesOverAssets	1.00%
Other Expenses	rr_OtherExpensesOverAssets	0.16%
Total Annual Fund Operating Expenses	rr_ExpensesOverAssets	1.72%
Expense Example, By Year, Column [Text]	rr_ExpenseExampleByYearColumnName	Class C Shares
1 Year	rr_ExpenseExampleYear01	275
3 Years	rr_ExpenseExampleYear03	542
5 Years	rr_ExpenseExampleYear05	933
10 Years	rr_ExpenseExampleYear10	2,030
Expense Example, No Redemption, By Year, Column [Text]	rr_ExpenseExampleNoRedemptionByYearColumnName	Class C Shares
1 Year	rr_ExpenseExampleNoRedemptionYear01	175
3 Years	rr_ExpenseExampleNoRedemptionYear03	542
5 Years	rr_ExpenseExampleNoRedemptionYear05	933
10 Years	rr_ExpenseExampleNoRedemptionYear10	2,030
Janus High-Yield Fund | Class A, C, S, I, N, R, T Shares | Class S
Risk/Return:	rr_RiskReturnAbstract
Shareholder Fees Column [Text]	rr_ShareholderFeesColumnName	Class S
Maximum Sales Charge (load) Imposed on Purchases (as a percentage of offering price)	rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice	none
Maximum Deferred Sales Charge (load) (as a percentage of the lower of original purchase price or redemption proceeds)	rr_MaximumDeferredSalesChargeOverOther	none
Operating Expenses Column [Text]	rr_OperatingExpensesColumnName	Class S
Management Fees	rr_ManagementFeesOverAssets	0.56%
Distribution/Service (12b-1) Fees	rr_DistributionAndService12b1FeesOverAssets	0.25%
Other Expenses	rr_OtherExpensesOverAssets	0.31%
Total Annual Fund Operating Expenses	rr_ExpensesOverAssets	1.12%
Expense Example, By Year, Column [Text]	rr_ExpenseExampleByYearColumnName	Class S Shares
1 Year	rr_ExpenseExampleYear01	114
3 Years	rr_ExpenseExampleYear03	356
5 Years	rr_ExpenseExampleYear05	617
10 Years	rr_ExpenseExampleYear10	1,363
Expense Example, No Redemption, By Year, Column [Text]	rr_ExpenseExampleNoRedemptionByYearColumnName	Class S Shares
1 Year	rr_ExpenseExampleNoRedemptionYear01	114
3 Years	rr_ExpenseExampleNoRedemptionYear03	356
5 Years	rr_ExpenseExampleNoRedemptionYear05	617
10 Years	rr_ExpenseExampleNoRedemptionYear10	1,363
Janus High-Yield Fund | Class A, C, S, I, N, R, T Shares | Class I
Risk/Return:	rr_RiskReturnAbstract
Shareholder Fees Column [Text]	rr_ShareholderFeesColumnName	Class I
Maximum Sales Charge (load) Imposed on Purchases (as a percentage of offering price)	rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice	none
Maximum Deferred Sales Charge (load) (as a percentage of the lower of original purchase price or redemption proceeds)	rr_MaximumDeferredSalesChargeOverOther	none
Operating Expenses Column [Text]	rr_OperatingExpensesColumnName	Class I
Management Fees	rr_ManagementFeesOverAssets	0.56%
Distribution/Service (12b-1) Fees	rr_DistributionAndService12b1FeesOverAssets	none
Other Expenses	rr_OtherExpensesOverAssets	0.12%
Total Annual Fund Operating Expenses	rr_ExpensesOverAssets	0.68%
Expense Example, By Year, Column [Text]	rr_ExpenseExampleByYearColumnName	Class I Shares
1 Year	rr_ExpenseExampleYear01	69
3 Years	rr_ExpenseExampleYear03	218
5 Years	rr_ExpenseExampleYear05	379
10 Years	rr_ExpenseExampleYear10	847
Expense Example, No Redemption, By Year, Column [Text]	rr_ExpenseExampleNoRedemptionByYearColumnName	Class I Shares
1 Year	rr_ExpenseExampleNoRedemptionYear01	69
3 Years	rr_ExpenseExampleNoRedemptionYear03	218
5 Years	rr_ExpenseExampleNoRedemptionYear05	379
10 Years	rr_ExpenseExampleNoRedemptionYear10	847
Janus High-Yield Fund | Class A, C, S, I, N, R, T Shares | Class N
Risk/Return:	rr_RiskReturnAbstract
Shareholder Fees Column [Text]	rr_ShareholderFeesColumnName	Class N
Maximum Sales Charge (load) Imposed on Purchases (as a percentage of offering price)	rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice	none
Maximum Deferred Sales Charge (load) (as a percentage of the lower of original purchase price or redemption proceeds)	rr_MaximumDeferredSalesChargeOverOther	none
Operating Expenses Column [Text]	rr_OperatingExpensesColumnName	Class N
Management Fees	rr_ManagementFeesOverAssets	0.56%
Distribution/Service (12b-1) Fees	rr_DistributionAndService12b1FeesOverAssets	none
Other Expenses	rr_OtherExpensesOverAssets	0.05%
Total Annual Fund Operating Expenses	rr_ExpensesOverAssets	0.61%
Expense Example, By Year, Column [Text]	rr_ExpenseExampleByYearColumnName	Class N Shares
1 Year	rr_ExpenseExampleYear01	62
3 Years	rr_ExpenseExampleYear03	195
5 Years	rr_ExpenseExampleYear05	340
10 Years	rr_ExpenseExampleYear10	762
Expense Example, No Redemption, By Year, Column [Text]	rr_ExpenseExampleNoRedemptionByYearColumnName	Class N Shares
1 Year	rr_ExpenseExampleNoRedemptionYear01	62
3 Years	rr_ExpenseExampleNoRedemptionYear03	195
5 Years	rr_ExpenseExampleNoRedemptionYear05	340
10 Years	rr_ExpenseExampleNoRedemptionYear10	762
Janus High-Yield Fund | Class A, C, S, I, N, R, T Shares | Class R
Risk/Return:	rr_RiskReturnAbstract
Shareholder Fees Column [Text]	rr_ShareholderFeesColumnName	Class R
Maximum Sales Charge (load) Imposed on Purchases (as a percentage of offering price)	rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice	none
Maximum Deferred Sales Charge (load) (as a percentage of the lower of original purchase price or redemption proceeds)	rr_MaximumDeferredSalesChargeOverOther	none
Operating Expenses Column [Text]	rr_OperatingExpensesColumnName	Class R
Management Fees	rr_ManagementFeesOverAssets	0.56%
Distribution/Service (12b-1) Fees	rr_DistributionAndService12b1FeesOverAssets	0.50%
Other Expenses	rr_OtherExpensesOverAssets	0.31%
Total Annual Fund Operating Expenses	rr_ExpensesOverAssets	1.37%
Expense Example, By Year, Column [Text]	rr_ExpenseExampleByYearColumnName	Class R Shares
1 Year	rr_ExpenseExampleYear01	139
3 Years	rr_ExpenseExampleYear03	434
5 Years	rr_ExpenseExampleYear05	750
10 Years	rr_ExpenseExampleYear10	1,646
Expense Example, No Redemption, By Year, Column [Text]	rr_ExpenseExampleNoRedemptionByYearColumnName	Class R Shares
1 Year	rr_ExpenseExampleNoRedemptionYear01	139
3 Years	rr_ExpenseExampleNoRedemptionYear03	434
5 Years	rr_ExpenseExampleNoRedemptionYear05	750
10 Years	rr_ExpenseExampleNoRedemptionYear10	1,646
Janus High-Yield Fund | Class A, C, S, I, N, R, T Shares | Class T
Risk/Return:	rr_RiskReturnAbstract
Shareholder Fees Column [Text]	rr_ShareholderFeesColumnName	Class T
Maximum Sales Charge (load) Imposed on Purchases (as a percentage of offering price)	rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice	none
Maximum Deferred Sales Charge (load) (as a percentage of the lower of original purchase price or redemption proceeds)	rr_MaximumDeferredSalesChargeOverOther	none
Operating Expenses Column [Text]	rr_OperatingExpensesColumnName	Class T
Management Fees	rr_ManagementFeesOverAssets	0.56%
Distribution/Service (12b-1) Fees	rr_DistributionAndService12b1FeesOverAssets	none
Other Expenses	rr_OtherExpensesOverAssets	0.31%
Total Annual Fund Operating Expenses	rr_ExpensesOverAssets	0.87%
Expense Example, By Year, Column [Text]	rr_ExpenseExampleByYearColumnName	Class T Shares
1 Year	rr_ExpenseExampleYear01	89
3 Years	rr_ExpenseExampleYear03	278
5 Years	rr_ExpenseExampleYear05	482
10 Years	rr_ExpenseExampleYear10	1,073
Expense Example, No Redemption, By Year, Column [Text]	rr_ExpenseExampleNoRedemptionByYearColumnName	Class T Shares
1 Year	rr_ExpenseExampleNoRedemptionYear01	89
3 Years	rr_ExpenseExampleNoRedemptionYear03	278
5 Years	rr_ExpenseExampleNoRedemptionYear05	482
10 Years	rr_ExpenseExampleNoRedemptionYear10	$ 1,073
2003	rr_AnnualReturn2003	16.04%
2004	rr_AnnualReturn2004	9.42%
2005	rr_AnnualReturn2005	2.77%
2006	rr_AnnualReturn2006	11.10%
2007	rr_AnnualReturn2007	1.35%
2008	rr_AnnualReturn2008	(19.32%)
2009	rr_AnnualReturn2009	40.86%
2010	rr_AnnualReturn2010	15.72%
2011	rr_AnnualReturn2011	3.20%
2012	rr_AnnualReturn2012	14.30%
Bar Chart, Year to Date Return, Date	rr_BarChartYearToDateReturnDate	Sep. 30, 2013
Bar Chart, Year to Date Return	rr_BarChartYearToDateReturn	3.54%
Highest Quarterly Return, Label	rr_HighestQuarterlyReturnLabel	Best Quarter:
Highest Quarterly Return, Date	rr_BarChartHighestQuarterlyReturnDate	Jun. 30, 2009
Highest Quarterly Return	rr_BarChartHighestQuarterlyReturn	14.93%
Lowest Quarterly Return, Label	rr_LowestQuarterlyReturnLabel	Worst Quarter:
Lowest Quarterly Return, Date	rr_BarChartLowestQuarterlyReturnDate	Dec. 31, 2008
Lowest Quarterly Return	rr_BarChartLowestQuarterlyReturn	(12.96%)
Janus High-Yield Fund | Class A, C, S, I, N, R, T Shares | Return Before Taxes | Class A
Risk/Return:	rr_RiskReturnAbstract
Column	rr_AverageAnnualReturnColumnName	Class A Shares
Label	rr_AverageAnnualReturnLabel	Return Before Taxes	[1]
1 Year	rr_AverageAnnualReturnYear01	8.65%
5 Years	rr_AverageAnnualReturnYear05	8.00%
10 Years	rr_AverageAnnualReturnYear10	7.97%
Since Inception	rr_AverageAnnualReturnSinceInception	7.84%
Inception Date	rr_AverageAnnualReturnInceptionDate	Dec. 29, 1995
Janus High-Yield Fund | Class A, C, S, I, N, R, T Shares | Return Before Taxes | Class C
Risk/Return:	rr_RiskReturnAbstract
Column	rr_AverageAnnualReturnColumnName	Class C Shares
Label	rr_AverageAnnualReturnLabel	Return Before Taxes	[2]
1 Year	rr_AverageAnnualReturnYear01	12.25%
5 Years	rr_AverageAnnualReturnYear05	8.28%
10 Years	rr_AverageAnnualReturnYear10	7.74%
Since Inception	rr_AverageAnnualReturnSinceInception	7.38%
Inception Date	rr_AverageAnnualReturnInceptionDate	Dec. 29, 1995
Janus High-Yield Fund | Class A, C, S, I, N, R, T Shares | Return Before Taxes | Class S
Risk/Return:	rr_RiskReturnAbstract
Column	rr_AverageAnnualReturnColumnName	Class S Shares
Label	rr_AverageAnnualReturnLabel	Return Before Taxes
1 Year	rr_AverageAnnualReturnYear01	13.88%
5 Years	rr_AverageAnnualReturnYear05	8.87%
10 Years	rr_AverageAnnualReturnYear10	8.28%
Since Inception	rr_AverageAnnualReturnSinceInception	7.92%
Inception Date	rr_AverageAnnualReturnInceptionDate	Dec. 29, 1995
Janus High-Yield Fund | Class A, C, S, I, N, R, T Shares | Return Before Taxes | Class I
Risk/Return:	rr_RiskReturnAbstract
Column	rr_AverageAnnualReturnColumnName	Class I Shares
Label	rr_AverageAnnualReturnLabel	Return Before Taxes
1 Year	rr_AverageAnnualReturnYear01	14.37%
5 Years	rr_AverageAnnualReturnYear05	9.18%
10 Years	rr_AverageAnnualReturnYear10	8.59%
Since Inception	rr_AverageAnnualReturnSinceInception	8.20%
Inception Date	rr_AverageAnnualReturnInceptionDate	Dec. 29, 1995
Janus High-Yield Fund | Class A, C, S, I, N, R, T Shares | Return Before Taxes | Class N
Risk/Return:	rr_RiskReturnAbstract
Column	rr_AverageAnnualReturnColumnName	Class N Shares
Label	rr_AverageAnnualReturnLabel	Return Before Taxes
1 Year	rr_AverageAnnualReturnYear01	14.30%
5 Years	rr_AverageAnnualReturnYear05	9.18%
10 Years	rr_AverageAnnualReturnYear10	8.59%
Since Inception	rr_AverageAnnualReturnSinceInception	8.20%
Inception Date	rr_AverageAnnualReturnInceptionDate	Dec. 29, 1995
Janus High-Yield Fund | Class A, C, S, I, N, R, T Shares | Return Before Taxes | Class R
Risk/Return:	rr_RiskReturnAbstract
Column	rr_AverageAnnualReturnColumnName	Class R Shares
Label	rr_AverageAnnualReturnLabel	Return Before Taxes
1 Year	rr_AverageAnnualReturnYear01	13.69%
5 Years	rr_AverageAnnualReturnYear05	8.58%
10 Years	rr_AverageAnnualReturnYear10	8.01%
Since Inception	rr_AverageAnnualReturnSinceInception	7.65%
Inception Date	rr_AverageAnnualReturnInceptionDate	Dec. 29, 1995
Janus High-Yield Fund | Class A, C, S, I, N, R, T Shares | Return Before Taxes | Class T
Risk/Return:	rr_RiskReturnAbstract
Column	rr_AverageAnnualReturnColumnName	Class T Shares
Label	rr_AverageAnnualReturnLabel	Return Before Taxes
1 Year	rr_AverageAnnualReturnYear01	14.30%
5 Years	rr_AverageAnnualReturnYear05	9.18%
10 Years	rr_AverageAnnualReturnYear10	8.59%
Since Inception	rr_AverageAnnualReturnSinceInception	8.20%
Inception Date	rr_AverageAnnualReturnInceptionDate	Dec. 29, 1995
Janus High-Yield Fund | Class A, C, S, I, N, R, T Shares | Return After Taxes on Distributions | Class T
Risk/Return:	rr_RiskReturnAbstract
Column	rr_AverageAnnualReturnColumnName	Class T Shares
Label	rr_AverageAnnualReturnLabel	Return After Taxes on Distributions
1 Year	rr_AverageAnnualReturnYear01	11.64%
5 Years	rr_AverageAnnualReturnYear05	5.95%
10 Years	rr_AverageAnnualReturnYear10	5.65%
Since Inception	rr_AverageAnnualReturnSinceInception	4.95%
Inception Date	rr_AverageAnnualReturnInceptionDate	Dec. 29, 1995
Janus High-Yield Fund | Class A, C, S, I, N, R, T Shares | Return After Taxes on Distributions and Sale of Fund Shares | Class T
Risk/Return:	rr_RiskReturnAbstract
Column	rr_AverageAnnualReturnColumnName	Class T Shares
Label	rr_AverageAnnualReturnLabel	Return After Taxes on Distributions and Sale of Fund Shares	[3]
1 Year	rr_AverageAnnualReturnYear01	9.23%
5 Years	rr_AverageAnnualReturnYear05	5.85%
10 Years	rr_AverageAnnualReturnYear10	5.58%
Since Inception	rr_AverageAnnualReturnSinceInception	4.98%
Inception Date	rr_AverageAnnualReturnInceptionDate	Dec. 29, 1995
Janus High-Yield Fund | Class A, C, S, I, N, R, T Shares | Barclays U.S. Corporate High-Yield Bond Index (reflects no deduction for expenses, fees, or taxes)
Risk/Return:	rr_RiskReturnAbstract
Label	rr_AverageAnnualReturnLabel	Barclays U.S. Corporate High-Yield Bond Index
1 Year	rr_AverageAnnualReturnYear01	15.81%
5 Years	rr_AverageAnnualReturnYear05	10.34%
10 Years	rr_AverageAnnualReturnYear10	10.62%
Since Inception	rr_AverageAnnualReturnSinceInception	7.66%
Inception Date	rr_AverageAnnualReturnInceptionDate	Dec. 29, 1995

[1] Calculated assuming maximum permitted sales loads.

[2] The one year return is calculated to include the contingent deferred sales charge.

[3] If the Fund incurs a loss, which generates a tax benefit, the Return After Taxes on Distributions and Sale of Fund Shares may exceed the Fund’s other return figures.

XML

Label	Element	Value
Risk/Return:	rr_RiskReturnAbstract
Registrant Name	dei_EntityRegistrantName	JANUS INVESTMENT FUND
Prospectus Date	rr_ProspectusDate	Oct. 28, 2013
Janus Real Return Fund | Class D Shares
Risk/Return:	rr_RiskReturnAbstract
Risk/Return [Heading]	rr_RiskReturnHeading	FUND SUMMARY Janus Real Return Fund
Objective [Heading]	rr_ObjectiveHeading	INVESTMENT OBJECTIVE
Objective, Primary [Text Block]	rr_ObjectivePrimaryTextBlock	Janus Real Return Fund seeks real return consistent with preservation of capital.
Expense [Heading]	rr_ExpenseHeading	FEES AND EXPENSES OF THE FUND
Expense Narrative [Text Block]	rr_ExpenseNarrativeTextBlock	This table describes the fees and expenses that you may pay if you buy and hold Shares of the Fund.
Operating Expenses Caption [Text]	rr_OperatingExpensesCaption	ANNUAL FUND OPERATING EXPENSES (expenses that you pay each year as a percentage of the value of your investment)
Fee Waiver or Reimbursement over Assets, Date of Termination	rr_FeeWaiverOrReimbursementOverAssetsDateOfTermination	November 1, 2014
Portfolio Turnover [Heading]	rr_PortfolioTurnoverHeading	Portfolio Turnover:
Portfolio Turnover [Text Block]	rr_PortfolioTurnoverTextBlock	The Fund pays transaction costs, such as commissions, when it buys and sells securities (or “turns over” its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when Fund shares are held in a taxable account. These costs, which are not reflected in annual fund operating expenses or in the Example, affect the Fund’s performance. During the most recent fiscal year, the Fund’s portfolio turnover rate was 112% of the average value of its portfolio.
Portfolio Turnover, Rate	rr_PortfolioTurnoverRate	112.00%
Expense Example [Heading]	rr_ExpenseExampleHeading	EXAMPLE:
Expense Example by Year [Heading]	rr_ExpenseExampleByYearHeading	The Example assumes that you invest $10,000 in the Fund for the time periods indicated, reinvest all dividends and distributions, and then redeem all of your Shares at the end of each period. The Example also assumes that your investment has a 5% return each year and that the Fund’s operating expenses without waivers or recoupments (if applicable) remain the same. Although your actual costs may be higher or lower, based on these assumptions your costs would be:
Expense Example Narrative [Text Block]	rr_ExpenseExampleNarrativeTextBlock	The following Example is based on expenses without waivers. The Example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds.
Strategy [Heading]	rr_StrategyHeading	PRINCIPAL INVESTMENT STRATEGIES
Strategy Narrative [Text Block]	rr_StrategyNarrativeTextBlock	The Fund pursues its investment objective by primarily investing in U.S. Treasury securities, short-duration high-yield/high-risk debt, commodity-linked investments, and equity securities. The Fund’s investments in U.S. Treasury securities may also include Treasury Inflation-Protected Securities, also known as TIPS. As utilized by the Fund, each of these types of investments may be considered an “inflation-related investment,” which are those that may provide what is known as “real return,” or a rate of return above the rate of inflation over a full market cycle. Due to the nature of securities in which the Fund invests, it may have relatively high portfolio turnover compared to other funds. The Fund may invest up to 90% of its net assets in short-duration high-yield/high-risk debt securities. The Fund’s investments in short-duration high-yield/high-risk securities include debt rated below investment grade, also known as “junk” bonds. Securities rated below investment grade may include their unrated equivalents or other high-yielding securities the portfolio managers believe offer attractive risk/return characteristics. The Fund may also invest in certain investment grade debt instruments, including corporate bonds, government bonds, municipal bonds, mortgage-backed securities, zero-coupon bonds, and agency securities. The Fund may invest in foreign debt securities. To seek exposure to the commodities markets, the Fund may invest in commodity-linked investments such as commodity-related exchange-traded funds (“ETFs”), commodity index-linked swap agreements, commodity options and futures, and options on futures that provide exposure to the investment returns of the commodities markets. The Fund may also invest in other commodity-linked derivative instruments, such as commodity-linked notes (“structured notes”). The Fund’s investments in equity securities may include common stock, preferred stock, and convertible securities, all of which may include exposure to foreign markets. The Fund may invest in companies of any market capitalization. The Fund’s equity investments may also include securities of real estate-related companies, including, but not limited to, real estate investment trusts (“REITs”) and similar REIT-like entities, such as foreign entities that have REIT characteristics. The Fund may also invest in derivative instruments (by taking long and/or short positions) for various purposes, including hedging by shorting interest rate futures against long positions in TIPS, using inflation index swaps to hedge against unexpected changes in the rate of inflation, using interest rate swaps to hedge against changes in interest rates, using currency swaps to adjust its currency exposure, to increase or decrease the Fund’s exposure to a particular market, to manage or adjust the risk profile of the Fund related to an investment, and to earn income and enhance returns. The Fund’s exposure to derivatives will vary, is not limited to those derivatives listed, and could be significant at times. The Fund may also use reverse repurchase agreements to generate income as part of its inflation-related strategies. Proceeds from reverse repurchase agreement transactions may be invested in other securities or instruments to attempt to increase the Fund’s investment return. The Fund may also invest in money market instruments, buy backs or dollar rolls, other securitized debt products, bank loans, various when-issued securities, exchange-traded notes, and other investment companies. In addition to considering economic factors such as the rate of inflation and the effect of interest rates on the Fund’s investments, the portfolio managers apply a “bottom up” approach in choosing investments. This means that the portfolio managers look at securities one at a time to determine if a security is an attractive investment opportunity and if it is consistent with the Fund’s investment policies. The Fund may lend portfolio securities on a short-term or long-term basis, in an amount equal to up to 1/3 of its total assets as determined at the time of the loan origination.
Risk [Heading]	rr_RiskHeading	PRINCIPAL INVESTMENT RISKS
Risk Narrative [Text Block]	rr_RiskNarrativeTextBlock	Although the Fund may be less volatile than funds that invest most of their assets in common stocks, the Fund’s returns and yields will vary, and you could lose money. Fixed-Income Securities Risk. The Fund invests in a variety of fixed-income securities. Typically, the values of fixed-income securities change inversely with prevailing interest rates. Therefore, a fundamental risk of fixed-income securities is interest rate risk, which is the risk that the value of such securities will generally decline as prevailing interest rates rise, which may cause the Fund’s net asset value to likewise decrease. How specific fixed-income securities may react to changes in interest rates will depend on the specific characteristics of each security. Fixed-income securities are also subject to credit risk, prepayment risk, valuation risk, and liquidity risk. Credit risk is the risk that the credit strength of an issuer of a fixed-income security will weaken and/or that the issuer will be unable to make timely principal and interest payments and that the security may go into default. Prepayment risk is the risk that during periods of falling interest rates, certain fixed-income securities with higher interest rates, such as mortgage- and asset-backed securities, may be prepaid by their issuers thereby reducing the amount of interest payments. Valuation risk is the risk that one or more of the fixed-income securities in which the Fund invests are priced differently than the value realized upon such security’s sale. In times of market instability, valuation may be more difficult. Liquidity risk is the risk that fixed-income securities may be difficult or impossible to sell at the time that the portfolio managers would like or at the price the portfolio managers believe the security is currently worth. High-Yield/High-Risk Bond Risk. The Fund may invest up to 90% of its net assets in higher-yielding/higher-risk bonds, also known as “junk” bonds. High-yield/high-risk bonds may be more sensitive than other types of bonds to economic changes, political changes, or adverse developments specific to the company that issued the bond, which may adversely affect their value. Sovereign Debt Risk. The Fund may invest in U.S. and foreign government debt securities (“sovereign debt”). Investments in U.S. sovereign debt are considered low risk. However, investments in non-U.S. sovereign debt can involve a high degree of risk, including the risk that the governmental entity that controls the repayment of sovereign debt may not be willing or able to repay the principal and/or to pay the interest on its sovereign debt in a timely manner. A sovereign debtor’s willingness or ability to satisfy its debt obligation may be affected by various factors including, but not limited to, its cash flow situation, the extent of its foreign currency reserves, the availability of foreign exchange when a payment is due, and the relative size of its debt position in relation to its economy as a whole. In the event of default, there may be limited or no legal remedies for collecting sovereign debt and there may be no bankruptcy proceedings through which the Fund may collect all or part of the sovereign debt that a governmental entity has not repaid. Foreign Exposure Risk. The Fund may have exposure to foreign markets as a result of its investments in foreign securities, including investments in emerging markets, which can be more volatile than the U.S. markets. As a result, its returns and net asset value may be affected to a large degree by fluctuations in currency exchange rates or political or economic conditions in a particular country. In some foreign markets, there may not be protection against failure by other parties to complete transactions. It may not be possible for the Fund to repatriate capital, dividends, interest, and other income from a particular country or governmental entity. In addition, a market swing in one or more countries or regions where the Fund has invested a significant amount of its assets may have a greater effect on the Fund’s performance than it would in a more geographically diversified portfolio. To the extent the Fund invests in foreign debt securities, such investments are sensitive to changes in interest rates. Additionally, investments in securities of foreign governments involve the risk that a foreign government may not be willing or able to pay interest or repay principal when due. Real Estate Securities Risk. The Fund’s performance may be affected by the risks associated with investments in real estate-related companies. The value of real estate-related companies’ securities is sensitive to changes in real estate values and rental income, property taxes, interest rates, tax and regulatory requirements, supply and demand, and the management skill and creditworthiness of the company. Investments in REITs involve the same risks as other real estate investments. In addition, a REIT could fail to qualify for tax-free pass-through of its income under the Internal Revenue Code or fail to maintain its exemption from registration under the Investment Company Act of 1940, as amended, which could produce adverse economic consequences for the REIT and its investors, including the Fund. Inflation-Related Investment Risk. Inflation index swaps, inflation-linked bonds (including Treasury Inflation-Protected Securities (“TIPS”)), and other inflation-linked securities are subject to inflation risk. A swap held long by the Fund can potentially lose value if the rate of inflation over the life of the swap is less than the fixed rate that the Fund agrees to pay at the initiation of the swap. Except for the Fund’s investments in TIPS, which are guaranteed as to principal by the U.S. Treasury, the inflation-adjusted principal value of inflation-linked bonds repaid at maturity may be less than the original principal. Because of their inflation-linked adjustment feature, inflation-linked bonds typically have lower yields than conventional fixed-rate securities. In the event of deflation, where prices decline over time, the principal and income of inflation-linked bonds will likely decline, resulting in losses to the Fund. Commodity-Linked Investments Risk. The Fund may invest in various commodity-linked investments that provide exposure to the commodities markets. Such exposure may subject the Fund to greater volatility than investments in traditional securities. The value of a given commodity-linked derivative investment typically is based upon the price movements of a physical commodity (such as heating oil, livestock, or agricultural products), a commodity futures contract or commodity index, or some other readily measurable economic variable. The value of commodity-linked derivative instruments may therefore be affected by changes in overall market movements, volatility of the underlying benchmark, changes in interest rates, or other factors affecting a particular industry or commodity such as drought, floods, weather, livestock disease, embargoes, tariffs, and international economic, political, and regulatory developments. Derivatives Risk. Derivatives can be highly volatile and involve risks in addition to the risks of the underlying referenced securities. Gains or losses from a derivative investment can be substantially greater than the derivative’s original cost, and can therefore involve leverage. Leverage may cause the Fund to be more volatile than if it had not used leverage. Derivatives can be complex instruments and may involve analysis that differs from that required for other investment types used by the Fund. If the value of a derivative does not correlate well with the particular market or other asset class to which the derivative is intended to provide exposure, the derivative may not produce the anticipated result. Derivatives can also reduce the opportunity for gain or result in losses by offsetting positive returns in other investments. Derivatives can be less liquid than other types of investments and entail the risk that the counterparty will default on its payment obligations. If the counterparty to a derivative transaction defaults, the Fund would risk the loss of the net amount of the payments that it contractually is entitled to receive. To the extent the Fund enters into short derivative positions, the Fund may be exposed to risks similar to those associated with short sales, including the risk that the Fund’s losses are theoretically unlimited. Counterparty Risk. Certain derivative and “over-the-counter” instruments, such as swaps and forwards, are subject to the risk that the other party to a contract will not fulfill its contractual obligations. Exchange-Traded Funds Risk. The Fund may invest in ETFs, which are typically open-end investment companies that are traded on a national securities exchange. ETFs typically incur fees, such as investment advisory fees and other operating expenses that are separate from those of the Fund, which will be indirectly paid by the Fund. As a result, the cost of investing in the Fund may be higher than the cost of investing directly in ETFs and may be higher than other mutual funds that invest directly in stocks and bonds. Further, the price movement of an ETF may fluctuate against the underlying securities or commodities it tracks and may result in a loss. Because the value of ETF shares depends on the demand in the market, the Fund may not be able to purchase or sell an ETF at the most optimal time, which could adversely affect the Fund’s performance. The ETFs in which the Fund invests are subject to specific risks, depending on the investment strategy of the ETF. In turn, the Fund will be subject to substantially the same risks as those associated with direct exposure to the securities or commodities held by the ETF. Because the Fund may invest in a broad range of ETFs, such risks may include, but are not limited to, leverage risk, foreign exposure risk, and commodities risk. Mortgage-Backed Securities Risk. Mortgage-backed securities are classified generally as either commercial mortgage-backed securities or residential mortgage-backed securities, each of which is subject to certain specific risks. Mortgage-backed securities tend to be more sensitive to changes in interest rates than other types of debt securities. Investments in mortgage-backed securities are subject to both extension risk, where borrowers extend the duration of their mortgages in times of rising interest rates, and prepayment risk, where borrowers pay off their mortgages sooner than expected in times of declining interest rates. These risks may reduce the Fund’s returns. In addition, investments in mortgage-backed securities, including those comprised of subprime mortgages, may be subject to a higher degree of credit risk, valuation risk, and liquidity risk than various other types of fixed-income securities. Reverse Repurchase Agreement Risk. Reverse repurchase agreements involve leverage risk, counterparty risk, and the risk that the value of securities that the Fund is obligated to repurchase under the agreement may decline below the repurchase price. When the Fund invests reverse repurchase transaction proceeds, the Fund is at risk for any fluctuations in the value of securities in which the proceeds are invested. To the extent the Fund uses reverse repurchase agreements, the value of an investment in the Fund may be more volatile, and such transactions may increase the Fund’s overall investment exposure. Additionally, interest expenses related to reverse repurchase transactions could exceed the rate of return on debt obligations and other investments held by the Fund, thereby reducing returns to shareholders. Nondiversification Risk. The Fund is classified as nondiversified under the Investment Company Act of 1940, as amended. This gives the Fund’s portfolio managers more flexibility to hold larger positions in a smaller number of securities. As a result, an increase or decrease in the value of a single security held by the Fund may have a greater impact on the Fund’s net asset value and total return. Portfolio Turnover Risk. Increased portfolio turnover may result in higher costs, which may have a negative effect on the Fund’s performance. In addition, higher portfolio turnover may result in the acceleration of capital gains and the recognition of greater levels of short-term capital gains, which are taxed at ordinary federal income tax rates when distributed to shareholders. Securities Lending Risk. The Fund may seek to earn additional income through lending its securities to certain qualified broker-dealers and institutions. There is the risk that when portfolio securities are lent, the securities may not be returned on a timely basis, and the Fund may experience delays and costs in recovering the security or gaining access to the collateral provided to the Fund to collateralize the loan. If the Fund is unable to recover a security on loan, the Fund may use the collateral to purchase replacement securities in the market. There is a risk that the value of the collateral could decrease below the cost of the replacement security by the time the replacement investment is made, resulting in a loss to the Fund. An investment in the Fund is not a bank deposit and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency.
Risk Lose Money [Text]	rr_RiskLoseMoney	Although the Fund may be less volatile than funds that invest most of their assets in common stocks, the Fund’s returns and yields will vary, and you could lose money.
Risk Nondiversified Status [Text]	rr_RiskNondiversifiedStatus	Nondiversification Risk. The Fund is classified as nondiversified under the Investment Company Act of 1940, as amended. This gives the Fund’s portfolio managers more flexibility to hold larger positions in a smaller number of securities. As a result, an increase or decrease in the value of a single security held by the Fund may have a greater impact on the Fund’s net asset value and total return.
Risk Not Insured Depository Institution [Text]	rr_RiskNotInsuredDepositoryInstitution	An investment in the Fund is not a bank deposit and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency.
Bar Chart and Performance Table [Heading]	rr_BarChartAndPerformanceTableHeading	PERFORMANCE INFORMATION
Performance Narrative [Text Block]	rr_PerformanceNarrativeTextBlock	The following information provides some indication of the risks of investing in the Fund by showing how the Fund’s performance has varied over time. The bar chart depicts the Fund’s performance during the period indicated. The table compares the Fund’s average annual returns for the periods indicated to broad-based securities market indices. The indices are not actively managed and are not available for direct investment. All figures assume reinvestment of dividends and distributions. For certain periods, the Fund’s performance reflects the effect of expense waivers. Without the effect of these expense waivers, the performance shown would have been lower. The Fund’s past performance (before and after taxes) does not necessarily indicate how it will perform in the future. Updated performance information is available at janus.com/allfunds or by calling 1-800-525-3713.
Performance Information Illustrates Variability of Returns [Text]	rr_PerformanceInformationIllustratesVariabilityOfReturns	The following information provides some indication of the risks of investing in the Fund by showing how the Fund’s performance has varied over time. The bar chart depicts the Fund’s performance during the period indicated.
Performance Additional Market Index [Text]	rr_PerformanceAdditionalMarketIndex	The table compares the Fund’s average annual returns for the periods indicated to broad-based securities market indices. The indices are not actively managed and are not available for direct investment. All figures assume reinvestment of dividends and distributions.
Performance Availability Phone [Text]	rr_PerformanceAvailabilityPhone	1-800-525-3713
Performance Availability Website Address [Text]	rr_PerformanceAvailabilityWebSiteAddress	janus.com/allfunds
Performance Past Does Not Indicate Future [Text]	rr_PerformancePastDoesNotIndicateFuture	The Fund’s past performance (before and after taxes) does not necessarily indicate how it will perform in the future.
Bar Chart [Heading]	rr_BarChartHeading	Annual Total Returns for Class D Shares (calendar year-end)
Bar Chart Closing [Text Block]	rr_BarChartClosingTextBlock	Best Quarter:  First Quarter 2012  5.63%          Worst Quarter:  Second Quarter 2012  −3.82%
Year to Date Return, Label	rr_YearToDateReturnLabel	The Fund’s year-to-date return as of the calendar quarter ended September 30, 2013 was 1.16%.
Performance Table Heading	rr_PerformanceTableHeading	Average Annual Total Returns (periods ended 12/31/12)
Performance Table Uses Highest Federal Rate	rr_PerformanceTableUsesHighestFederalRate	After-tax returns are calculated using the historically highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes.
Performance Table Not Relevant to Tax Deferred	rr_PerformanceTableNotRelevantToTaxDeferred	Actual after-tax returns depend on your individual tax situation and may differ from those shown in the preceding table. The after-tax return information shown above does not apply to Fund shares held through a tax-deferred account, such as a 401(k) plan or an IRA.
Performance Table Explanation after Tax Higher	rr_PerformanceTableExplanationAfterTaxHigher	If the Fund incurs a loss, which generates a tax benefit, the Return After Taxes on Distributions and Sale of Fund Shares may exceed the Fund’s other return figures.
Performance Table Narrative	rr_PerformanceTableNarrativeTextBlock	Effective October 15, 2012, the Fund’s primary benchmark index changed from the Barclays U.S. TIPS Index to the Barclays U.S. 1-5 Year TIPS Index. Additionally, the Fund changed its secondary benchmark index from the Consumer Price Index +400 to the Consumer Price Index +200. Janus Capital believes that the foregoing benchmark index changes provide a more appropriate representation of the Fund’s investment strategy. After-tax returns are calculated using the historically highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes. Actual after-tax returns depend on your individual tax situation and may differ from those shown in the preceding table. The after-tax return information shown above does not apply to Fund shares held through a tax-deferred account, such as a 401(k) plan or an IRA.
Performance Table Closing [Text Block]	rr_PerformanceTableClosingTextBlock	Updated performance information is available at janus.com/allfunds or by calling 1-800-525-3713.
Janus Real Return Fund | Class D Shares | Class D
Risk/Return:	rr_RiskReturnAbstract
Operating Expenses Column [Text]	rr_OperatingExpensesColumnName	Class D
Management Fees	rr_ManagementFeesOverAssets	0.55%
Other Expenses	rr_OtherExpensesOverAssets	2.53%	[1]
Total Annual Fund Operating Expenses	rr_ExpensesOverAssets	3.08%	[2]
Fee Waiver	rr_FeeWaiverOrReimbursementOverAssets	2.20%	[2]
Total Annual Fund Operating Expenses After Fee Waiver	rr_NetExpensesOverAssets	0.88%	[2]
Expense Example, By Year, Column [Text]	rr_ExpenseExampleByYearColumnName	Class D Shares
1 Year	rr_ExpenseExampleYear01	$ 311
3 Years	rr_ExpenseExampleYear03	951
5 Years	rr_ExpenseExampleYear05	1,616
10 Years	rr_ExpenseExampleYear10	$ 3,392
2012	rr_AnnualReturn2012	4.87%
Bar Chart, Year to Date Return, Date	rr_BarChartYearToDateReturnDate	Sep. 30, 2013
Bar Chart, Year to Date Return	rr_BarChartYearToDateReturn	1.16%
Highest Quarterly Return, Label	rr_HighestQuarterlyReturnLabel	Best Quarter:
Highest Quarterly Return, Date	rr_BarChartHighestQuarterlyReturnDate	Mar. 31, 2012
Highest Quarterly Return	rr_BarChartHighestQuarterlyReturn	5.63%
Lowest Quarterly Return, Label	rr_LowestQuarterlyReturnLabel	Worst Quarter:
Lowest Quarterly Return, Date	rr_BarChartLowestQuarterlyReturnDate	Jun. 30, 2012
Lowest Quarterly Return	rr_BarChartLowestQuarterlyReturn	(3.82%)
Janus Real Return Fund | Class D Shares | Return Before Taxes | Class D
Risk/Return:	rr_RiskReturnAbstract
Column	rr_AverageAnnualReturnColumnName	Class D Shares
Label	rr_AverageAnnualReturnLabel	Return Before Taxes
1 Year	rr_AverageAnnualReturnYear01	4.87%
Since Inception	rr_AverageAnnualReturnSinceInception	(0.24%)
Inception Date	rr_AverageAnnualReturnInceptionDate	May 13, 2011
Janus Real Return Fund | Class D Shares | Return After Taxes on Distributions | Class D
Risk/Return:	rr_RiskReturnAbstract
Column	rr_AverageAnnualReturnColumnName	Class D Shares
Label	rr_AverageAnnualReturnLabel	Return After Taxes on Distributions
1 Year	rr_AverageAnnualReturnYear01	4.69%
Since Inception	rr_AverageAnnualReturnSinceInception	(0.48%)
Inception Date	rr_AverageAnnualReturnInceptionDate	May 13, 2011
Janus Real Return Fund | Class D Shares | Return After Taxes on Distributions and Sale of Fund Shares | Class D
Risk/Return:	rr_RiskReturnAbstract
Column	rr_AverageAnnualReturnColumnName	Class D Shares
Label	rr_AverageAnnualReturnLabel	Return After Taxes on Distributions and Sale of Fund Shares	[3]
1 Year	rr_AverageAnnualReturnYear01	3.27%
Since Inception	rr_AverageAnnualReturnSinceInception	(0.29%)
Inception Date	rr_AverageAnnualReturnInceptionDate	May 13, 2011
Janus Real Return Fund | Class D Shares | Barclays U.S. 1-5 Year TIPS Index (reflects no deduction for expenses, fees, or taxes)
Risk/Return:	rr_RiskReturnAbstract
Label	rr_AverageAnnualReturnLabel	Barclays U.S. 1-5 Year TIPS Index
1 Year	rr_AverageAnnualReturnYear01	2.66%
Since Inception	rr_AverageAnnualReturnSinceInception	2.44%
Inception Date	rr_AverageAnnualReturnInceptionDate	May 13, 2011
Janus Real Return Fund | Class D Shares | Consumer Price Index +200 (reflects no deduction for expenses, fees, or taxes)
Risk/Return:	rr_RiskReturnAbstract
Label	rr_AverageAnnualReturnLabel	Consumer Price Index +200
1 Year	rr_AverageAnnualReturnYear01	4.02%
Since Inception	rr_AverageAnnualReturnSinceInception	2.99%
Inception Date	rr_AverageAnnualReturnInceptionDate	May 13, 2011
Janus Real Return Fund | Class D Shares | Barclays U.S. TIPS Index (reflects no deduction for expenses, fees, or taxes)
Risk/Return:	rr_RiskReturnAbstract
Label	rr_AverageAnnualReturnLabel	Barclays U.S. TIPS Index
1 Year	rr_AverageAnnualReturnYear01	6.98%
Since Inception	rr_AverageAnnualReturnSinceInception	9.76%
Inception Date	rr_AverageAnnualReturnInceptionDate	May 13, 2011
Janus Real Return Fund | Class D Shares | Consumer Price Index +400 (reflects no deduction for expenses, fees, or taxes)
Risk/Return:	rr_RiskReturnAbstract
Label	rr_AverageAnnualReturnLabel	Consumer Price Index +400
1 Year	rr_AverageAnnualReturnYear01	6.02%
Since Inception	rr_AverageAnnualReturnSinceInception	4.97%
Inception Date	rr_AverageAnnualReturnInceptionDate	May 13, 2011

[1] Other Expenses are based on the estimated expenses that the Fund expects to incur.

[2] Janus Capital has contractually agreed to waive its investment advisory fee and/or reimburse Fund expenses to the extent that the Fund’s total annual fund operating expenses (excluding administrative services fees payable pursuant to the Transfer Agency Agreement, brokerage commissions, interest, dividends, taxes, acquired fund fees and expenses, and extraordinary expenses) exceed 0.76% until at least November 1, 2014. The contractual waiver may be terminated or modified prior to this date only at the discretion of the Board of Trustees. For a period of three years subsequent to the Fund’s commencement of operations (May 13, 2011) or until the Fund’s assets exceed the first breakpoint in the investment advisory fee schedule that was effective at commencement of operations, whichever occurs first, Janus Capital may recover from the Fund fees and expenses previously waived or reimbursed, which could then be considered a deferral, if the Fund’s expense ratio, including recovered expenses, falls below the expense limit.

[3] If the Fund incurs a loss, which generates a tax benefit, the Return After Taxes on Distributions and Sale of Fund Shares may exceed the Fund’s other return figures.

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Janus Flexible Bond Fund | Class A, C, S, I, N, R, T Shares

FUND SUMMARY

Janus Flexible Bond Fund

INVESTMENT OBJECTIVE

Janus Flexible Bond Fund seeks to obtain maximum total return, consistent with preservation of capital.

FEES AND EXPENSES OF THE FUND

This table describes the fees and expenses that you may pay if you buy and hold Shares of the Fund. Each share class has different expenses, but represents an investment in the same Fund.

For Class A Shares, you may qualify for sales charge discounts if you and your family invest, or agree to invest in the future, at least $50,000 in the Fund or in other Janus mutual funds. More information about these and other discounts, as well as eligibility requirements for each share class, is available from your financial professional and in the “Purchases” section on page 64 of the Fund’s Prospectus and in the “Purchases” section on page 70 of the Fund’s Statement of Additional Information.

SHAREHOLDER FEES
(fees paid directly from your investment)

Shareholder Fees Janus Flexible Bond Fund Class A, C, S, I, N, R, T Shares	Class A	Class C	Class S	Class I	Class N	Class R	Class T
Shareholder Fees Column [Text]	Class A	Class C	Class S	Class I	Class N	Class R	Class T
Maximum Sales Charge (load) Imposed on Purchases (as a percentage of offering price)	4.75%	none	none	none	none	none	none
Maximum Deferred Sales Charge (load) (as a percentage of the lower of original purchase price or redemption proceeds)	none	1.00%	none	none	none	none	none

ANNUAL FUND OPERATING EXPENSES
(expenses that you pay each year as a percentage of the value of your investment)

Annual Fund Operating Expenses Janus Flexible Bond Fund Class A, C, S, I, N, R, T Shares	Class A	Class C	Class S	Class I	Class N	Class R	Class T
Operating Expenses Column [Text]	Class A	Class C	Class S	Class I	Class N	Class R	Class T
Management Fees	0.40%	0.40%	0.40%	0.40%	0.40%	0.40%	0.40%
Distribution/Service (12b-1) Fees	0.25%	1.00%	0.25%	none	none	0.50%	none
Other Expenses	0.10%	0.15%	0.30%	0.16%	0.04%	0.29%	0.30%
Total Annual Fund Operating Expenses	0.75%	1.55%	0.95%	0.56%	0.44%	1.19%	0.70%

EXAMPLE:

The Example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds.

The Example assumes that you invest $10,000 in the Fund for the time periods indicated and reinvest all dividends and distributions. The Example also assumes that your investment has a 5% return each year and that the Fund’s operating expenses remain the same. Although your actual costs may be higher or lower, based on these assumptions your costs would be:

If Shares are redeemed:

Expense Example Janus Flexible Bond Fund Class A, C, S, I, N, R, T Shares (USD $)	Expense Example, By Year, Column [Text]	1 Year	3 Years	5 Years	10 Years
Class A	Class A Shares	548	703	872	1,361
Class C	Class C Shares	258	490	845	1,845
Class S	Class S Shares	97	303	525	1,166
Class I	Class I Shares	57	179	313	701
Class N	Class N Shares	45	141	246	555
Class R	Class R Shares	121	378	654	1,443
Class T	Class T Shares	72	224	390	871

If Shares are not redeemed:

Expense Example, No Redemption Janus Flexible Bond Fund Class A, C, S, I, N, R, T Shares (USD $)	Expense Example, No Redemption, By Year, Column [Text]	1 Year	3 Years	5 Years	10 Years
Class A	Class A Shares	548	703	872	1,361
Class C	Class C Shares	158	490	845	1,845
Class S	Class S Shares	97	303	525	1,166
Class I	Class I Shares	57	179	313	701
Class N	Class N Shares	45	141	246	555
Class R	Class R Shares	121	378	654	1,443
Class T	Class T Shares	72	224	390	871

Portfolio Turnover:

The Fund pays transaction costs, such as commissions, when it buys and sells securities (or “turns over” its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when Fund shares are held in a taxable account. These costs, which are not reflected in annual fund operating expenses or in the Example, affect the Fund’s performance. During the most recent fiscal year, the Fund’s portfolio turnover rate was 118% of the average value of its portfolio.

PRINCIPAL INVESTMENT STRATEGIES

The Fund pursues its investment objective by primarily investing, under normal circumstances, at least 80% of its net assets in bonds. Bonds include, but are not limited to, government notes and bonds, corporate bonds, convertible bonds, commercial and residential mortgage-backed securities, and zero-coupon bonds. The Fund will invest at least 65% of its assets in investment grade debt securities. As of June 30, 2013, the Fund’s weighted average maturity was 6.9 years. The Fund will limit its investment in high-yield/high-risk bonds, also known as “junk” bonds, to 35% or less of its net assets. The Fund generates total return from a combination of current income and capital appreciation, but income is usually the dominant portion. The Fund may also invest in asset-backed securities, money market instruments, bank loans, and foreign debt securities (which may include investments in emerging markets). Due to the nature of the securities in which the Fund invests, it may have relatively high portfolio turnover compared to other Funds.

In addition, the Fund may invest its assets in derivatives, which are instruments that have a value derived from, or directly linked to, an underlying asset, such as equity securities, fixed-income securities, commodities, currencies, interest rates, or market indices. In particular, the Fund may use interest rate futures to manage portfolio risk. The Fund’s exposure to derivatives will vary. For purposes of meeting its 80% investment policy, the Fund may include derivatives that have characteristics similar to the securities in which the Fund may directly invest.

In addition to considering economic factors such as the effect of interest rates on the Fund’s investments, the portfolio managers apply a “bottom up” approach in choosing investments. This means that the portfolio managers look at income-producing securities one at a time to determine if a security is an attractive investment opportunity and if it is consistent with the Fund’s investment policies.

The Fund may lend portfolio securities on a short-term or long-term basis, in an amount equal to up to 1/3 of its total assets as determined at the time of the loan origination.

PRINCIPAL INVESTMENT RISKS

Although the Fund may be less volatile than funds that invest most of their assets in common stocks, the Fund’s returns and yields will vary, and you could lose money.

Fixed-Income Securities Risk. The Fund invests in a variety of fixed-income securities. Typically, the values of fixed-income securities change inversely with prevailing interest rates. Therefore, a fundamental risk of fixed-income securities is interest rate risk, which is the risk that the value of such securities will generally decline as prevailing interest rates rise, which may cause the Fund’s net asset value to likewise decrease. How specific fixed-income securities may react to changes in interest rates will depend on the specific characteristics of each security. Fixed-income securities are also subject to credit risk, prepayment risk, valuation risk, and liquidity risk. Credit risk is the risk that the credit strength of an issuer of a fixed-income security will weaken and/or that the issuer will be unable to make timely principal and interest payments and that the security may go into default. Prepayment risk is the risk that during periods of falling interest rates, certain fixed-income securities with higher interest rates, such as mortgage- and asset-backed securities, may be prepaid by their issuers thereby reducing the amount of interest payments. Valuation risk is the risk that one or more of the fixed-income securities in which the Fund invests are priced differently than the value realized upon such security’s sale. In times of market instability, valuation may be more difficult. Liquidity risk is the risk that fixed-income securities may be difficult or impossible to sell at the time that the portfolio managers would like or at the price the portfolio managers believe the security is currently worth.

Mortgage-Backed Securities Risk. Mortgage-backed securities are classified generally as either commercial mortgage-backed securities or residential mortgage-backed securities, each of which is subject to certain specific risks. Mortgage-backed securities tend to be more sensitive to changes in interest rates than other types of debt securities. Investments in mortgage-backed securities are subject to both extension risk, where borrowers extend the duration of their mortgages in times of rising interest rates, and prepayment risk, where borrowers pay off their mortgages sooner than expected in times of declining interest rates. These risks may reduce the Fund’s returns. In addition, investments in mortgage-backed securities, including those comprised of subprime mortgages, may be subject to a higher degree of credit risk, valuation risk, and liquidity risk than various other types of fixed-income securities.

Sovereign Debt Risk. The Fund may invest in U.S. and foreign government debt securities (“sovereign debt”). Investments in U.S. sovereign debt are considered low risk. However, investments in non-U.S. sovereign debt can involve a high degree of risk, including the risk that the governmental entity that controls the repayment of sovereign debt may not be willing or able to repay the principal and/or to pay the interest on its sovereign debt in a timely manner. A sovereign debtor’s willingness or ability to satisfy its debt obligation may be affected by various factors including, but not limited to, its cash flow situation, the extent of its foreign currency reserves, the availability of foreign exchange when a payment is due, and the relative size of its debt position in relation to its economy as a whole. In the event of default, there may be limited or no legal remedies for collecting sovereign debt and there may be no bankruptcy proceedings through which the Fund may collect all or part of the sovereign debt that a governmental entity has not repaid.

High-Yield/High-Risk Bond Risk. High-yield/high-risk bonds may be more sensitive than other types of bonds to economic changes, political changes, or adverse developments specific to the company that issued the bond, which may adversely affect their value.

Bank Loan Risk. Bank loans are obligations of companies or other entities entered into in connection with recapitalizations, acquisitions, and refinancings. The Fund’s investments in bank loans are generally acquired as a participation interest in, or assignment of, loans originated by a lender or other financial institution. These investments may include institutionally-traded floating and fixed-rate debt securities. Participation interests and assignments involve credit, interest rate, and liquidity risk. In addition, the bank loans underlying these securities often involve borrowers with low credit ratings whose financial conditions are troubled or uncertain, including companies that are highly leveraged or in bankruptcy proceedings.

Foreign Exposure Risk. The Fund may have exposure to foreign markets as a result of its investments in foreign securities, including investments in emerging markets, which can be more volatile than the U.S. markets. As a result, its returns and net asset value may be affected to a large degree by fluctuations in currency exchange rates or political or economic conditions in a particular country. In some foreign markets, there may not be protection against failure by other parties to complete transactions. It may not be possible for the Fund to repatriate capital, dividends, interest, and other income from a particular country or governmental entity. In addition, a market swing in one or more countries or regions where the Fund has invested a significant amount of its assets may have a greater effect on the Fund’s performance than it would in a more geographically diversified portfolio. To the extent the Fund invests in foreign debt securities, such investments are sensitive to changes in interest rates. Additionally, investments in securities of foreign governments involve the risk that a foreign government may not be willing or able to pay interest or repay principal when due. The Fund’s investments in emerging market countries may involve risks greater than, or in addition to, the risks of investing in more developed countries.

Portfolio Turnover Risk. Increased portfolio turnover may result in higher costs, which may have a negative effect on the Fund’s performance. In addition, higher portfolio turnover may result in the acceleration of capital gains and the recognition of greater levels of short-term capital gains, which are taxed at ordinary federal income tax rates when distributed to shareholders.

Derivatives Risk. Derivatives can be highly volatile and involve risks in addition to the risks of the underlying referenced securities. Gains or losses from a derivative investment can be substantially greater than the derivative’s original cost, and can therefore involve leverage. Leverage may cause the Fund to be more volatile than if it had not used leverage. Derivatives can be less liquid than other types of investments and entail the risk that the counterparty will default on its payment obligations.

Securities Lending Risk. The Fund may seek to earn additional income through lending its securities to certain qualified broker-dealers and institutions. There is the risk that when portfolio securities are lent, the securities may not be returned on a timely basis, and the Fund may experience delays and costs in recovering the security or gaining access to the collateral provided to the Fund to collateralize the loan. If the Fund is unable to recover a security on loan, the Fund may use the collateral to purchase replacement securities in the market. There is a risk that the value of the collateral could decrease below the cost of the replacement security by the time the replacement investment is made, resulting in a loss to the Fund.

An investment in the Fund is not a bank deposit and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency.

PERFORMANCE INFORMATION

The following information provides some indication of the risks of investing in the Fund by showing how the Fund’s performance has varied over time. Class T Shares (formerly named Class J Shares, the initial share class) of the Fund commenced operations with the Fund’s inception. Class A Shares, Class C Shares, Class S Shares, Class I Shares, and Class R Shares of the Fund commenced operations on July 6, 2009. Class N Shares of the Fund commenced operations on May 31, 2012.

• The performance shown for Class T Shares is calculated using the fees and expenses of Class T Shares in effect during the periods shown, net of any applicable fee and expense limitations or waivers.
• The performance shown for Class A Shares, Class C Shares, Class S Shares, and Class R Shares for periods prior to July 6, 2009, reflects the performance of the Fund’s former Class J Shares, calculated using the fees and expenses of each respective share class, without the effect of any fee and expense limitations or waivers.
• The performance shown for Class I Shares for periods prior to July 6, 2009, reflects the performance of the Fund’s former Class J Shares, calculated using the fees and expenses of Class J Shares, net of any applicable fee and expense limitations or waivers.
• The performance shown for Class N Shares for periods prior to May 31, 2012, reflects the performance of the Fund’s Class T Shares, calculated using the fees and expenses of Class T Shares, net of any applicable fee and expense limitations or waivers.

If Class A Shares, Class C Shares, Class S Shares, Class I Shares, and Class R Shares of the Fund had been available during periods prior to July 6, 2009, or Class N Shares of the Fund had been available during periods prior to May 31, 2012, the performance shown for each respective share class may have been different. The performance shown for periods following the Fund’s commencement of Class A Shares, Class C Shares, Class S Shares, Class I Shares, Class N Shares, and Class R Shares reflects the fees and expenses of each respective share class, net of any applicable fee and expense limitations or waivers.

The bar chart depicts the change in performance from year to year during the periods indicated. The bar chart figures do not include any applicable sales charges that an investor may pay when they buy or sell Class A Shares or Class C Shares of the Fund. If sales charges were included, the returns would be lower. The table compares the Fund’s average annual returns for the periods indicated to a broad-based securities market index. The index is not actively managed and is not available for direct investment. All figures assume reinvestment of dividends and distributions. For certain periods, the Fund’s performance reflects the effect of expense waivers. Without the effect of these expense waivers, the performance shown would have been lower.

The Fund’s past performance (before and after taxes) does not necessarily indicate how it will perform in the future. Updated performance information is available at janus.com/advisor/mutual-funds or by calling 1-877-335-2687.

Annual Total Returns for Class T Shares (calendar year-end)

Best Quarter:  Third Quarter 2009  5.58%          Worst Quarter:  Second Quarter 2004  −2.99%

The Fund’s year-to-date return as of the calendar quarter ended September 30, 2013 was −0.95%.

Average Annual Total Returns (periods ended 12/31/12)

Average Annual Total Returns Janus Flexible Bond Fund Class A, C, S, I, N, R, T Shares	Column	Label		1 Year	5 Years	10 Years	Since Inception	Inception Date
Class T Return Before Taxes	Class T Shares	Return Before Taxes		7.91%	7.98%	6.27%	7.55%	Jul. 07, 1987
Class T Return After Taxes on Distributions	Class T Shares	Return After Taxes on Distributions		6.24%	6.14%	4.52%	4.97%	Jul. 07, 1987
Class T Return After Taxes on Distributions and Sale of Fund Shares	Class T Shares	Return After Taxes on Distributions and Sale of Fund Shares		5.31%	5.82%	4.36%	4.91%	Jul. 07, 1987
Class A Return Before Taxes	Class A Shares	Return Before Taxes	[1]	2.66%	6.87%	5.71%	7.33%	Jul. 07, 1987
Class C Return Before Taxes	Class C Shares	Return Before Taxes	[2]	5.97%	7.14%	5.48%	6.85%	Jul. 07, 1987
Class S Return Before Taxes	Class S Shares	Return Before Taxes		7.54%	7.71%	6.03%	7.39%	Jul. 07, 1987
Class I Return Before Taxes	Class I Shares	Return Before Taxes		8.06%	7.98%	6.27%	7.55%	Jul. 07, 1987
Class N Return Before Taxes	Class N Shares	Return Before Taxes		7.91%	7.98%	6.27%	7.55%	Jul. 07, 1987
Class R Return Before Taxes	Class R Shares	Return Before Taxes		7.40%	7.46%	5.77%	7.13%	Jul. 07, 1987
Barclays U.S. Aggregate Bond Index (reflects no deduction for expenses, fees, or taxes)		Barclays U.S. Aggregate Bond Index		4.21%	5.95%	5.18%	7.21%	Jul. 07, 1987

After-tax returns are calculated using distributions for the Fund's Class T Shares (formerly named Class J Shares, the initial share class). After-tax returns are calculated using the historically highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes. Actual after-tax returns depend on your individual tax situation and may differ from those shown in the preceding table. The after-tax return information shown above does not apply to Fund shares held through a tax-deferred account, such as a 401(k) plan or an IRA.

After-tax returns are only shown for Class T Shares of the Fund. After-tax returns for the other classes of Shares will vary from those shown for Class T Shares due to varying sales charges (as applicable), fees, and expenses among the classes.

[1] Calculated assuming maximum permitted sales loads.

[2] The one year return is calculated to include the contingent deferred sales charge.

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INTECH U.S. Core Fund | Class A, C, S, I, T Shares

FUND SUMMARY

INTECH U.S. Core Fund

INVESTMENT OBJECTIVE

INTECH U.S. Core Fund seeks long-term growth of capital.

FEES AND EXPENSES OF THE FUND

This table describes the fees and expenses that you may pay if you buy and hold Shares of the Fund. Each share class has different expenses, but represents an investment in the same Fund.

For Class A Shares, you may qualify for sales charge discounts if you and your family invest, or agree to invest in the future, at least $50,000 in the Fund or in other Janus mutual funds. More information about these and other discounts, as well as eligibility requirements for each share class, is available from your financial professional and in the “Purchases” section on page 51 of the Fund’s Prospectus and in the “Purchases” section on page 70 of the Fund’s Statement of Additional Information.

SHAREHOLDER FEES
(fees paid directly from your investment)

Shareholder Fees INTECH U.S. Core Fund Class A, C, S, I, T Shares	Class A	Class C	Class S	Class I	Class T
Shareholder Fees Column [Text]	Class A	Class C	Class S	Class I	Class T
Maximum Sales Charge (load) Imposed on Purchases (as a percentage of offering price)	5.75%	none	none	none	none
Maximum Deferred Sales Charge (load) (as a percentage of the lower of original purchase price or redemption proceeds)	none	1.00%	none	none	none

ANNUAL FUND OPERATING EXPENSES
(expenses that you pay each year as a percentage of the value of your investment)

Annual Fund Operating Expenses INTECH U.S. Core Fund Class A, C, S, I, T Shares	Class A	Class C	Class S	Class I	Class T
Operating Expenses Column [Text]	Class A	Class C	Class S	Class I	Class T
Management Fees (may adjust up or down)	0.60%	0.60%	0.60%	0.60%	0.60%
Distribution/Service (12b-1) Fees	0.25%	1.00%	0.25%	none	none
Other Expenses	0.13%	0.17%	0.32%	0.15%	0.32%
Total Annual Fund Operating Expenses	0.98%	1.77%	1.17%	0.75%	0.92%

EXAMPLE:

The Example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds.

The Example assumes that you invest $10,000 in the Fund for the time periods indicated and reinvest all dividends and distributions. The Example also assumes that your investment has a 5% return each year and that the Fund’s operating expenses remain the same. Although your actual costs may be higher or lower, based on these assumptions your costs would be:

If Shares are redeemed:

Expense Example INTECH U.S. Core Fund Class A, C, S, I, T Shares (USD $)	Expense Example, By Year, Column [Text]	1 Year	3 Years	5 Years	10 Years
Class A	Class A Shares	669	869	1,086	1,707
Class C	Class C Shares	280	557	959	2,084
Class S	Class S Shares	119	372	644	1,420
Class I	Class I Shares	77	240	417	930
Class T	Class T Shares	94	293	509	1,131

If Shares are not redeemed:

Expense Example, No Redemption INTECH U.S. Core Fund Class A, C, S, I, T Shares (USD $)	Expense Example, No Redemption, By Year, Column [Text]	1 Year	3 Years	5 Years	10 Years
Class A	Class A Shares	669	869	1,086	1,707
Class C	Class C Shares	180	557	959	2,084
Class S	Class S Shares	119	372	644	1,420
Class I	Class I Shares	77	240	417	930
Class T	Class T Shares	94	293	509	1,131

Portfolio Turnover: 

The Fund pays transaction costs, such as commissions, when it buys and sells securities (or “turns over” its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when Fund shares are held in a taxable account. These costs, which are not reflected in annual fund operating expenses or in the Example, affect the Fund’s performance. During the most recent fiscal year, the Fund’s portfolio turnover rate was 67% of the average value of its portfolio.

PRINCIPAL INVESTMENT STRATEGIES

The Fund invests, under normal circumstances, at least 80% of its net assets in U.S. common stocks from the universe of the S&P 500^® Index, utilizing INTECH’s mathematical investment process. The S&P 500^® Index is an unmanaged index of 500 stocks that is generally representative of the performance of larger companies in the United States.

The Fund pursues its investment objective by applying a mathematical investment process to construct an investment portfolio from the universe of common stocks within its named benchmark index. The goal of this process is to build a portfolio of stocks in a more efficient combination than the named benchmark index. The process seeks to capitalize on the natural volatility of the market by searching for stocks within the index that have high relative volatility (providing the potential for excess returns) but that essentially move in opposite directions or have low correlation to each other (providing the potential for lower relative risk). By constructing the portfolio in this manner and periodically rebalancing the portfolio to maintain potentially more efficient weightings, INTECH’s mathematical investment process seeks to create a portfolio that, over time, produces returns in excess of its named benchmark index with risks similar to that of the benchmark index. The rebalancing techniques used by INTECH may result in a higher portfolio turnover compared to a “buy and hold” fund strategy.

The Fund may lend portfolio securities on a short-term or long-term basis, in an amount equal to up to 1/3 of its total assets as determined at the time of the loan origination.

PRINCIPAL INVESTMENT RISKS

The biggest risk is that the Fund’s returns will vary, and you could lose money. The Fund is designed for long-term investors seeking an equity portfolio, including common stocks. Common stocks tend to be more volatile than many other investment choices.

Market Risk. The value of the Fund’s portfolio may decrease if the value of an individual company or security, or multiple companies or securities, in the portfolio decreases. Further, regardless of how well individual companies or securities perform, the value of the Fund’s portfolio could also decrease if there are deteriorating economic or market conditions. It is important to understand that the value of your investment may fall, sometimes sharply, in response to changes in the market, and you could lose money.

Investment Process Risk. The proprietary mathematical investment process used by INTECH may not achieve the desired results. There is a risk that INTECH’s method of identifying stocks with higher volatility than the named benchmark index or its method of identifying stocks that tend to move in the same or opposite direction relative to each other (correlation) will not result in selecting stocks with continuing volatility or the expected correlation. In INTECH’s history, which spans more than 25 years, INTECH’s mathematical investment process has experienced periods of both underperformance and outperformance relative to an identified benchmark. Even when the proprietary mathematical investment process is working appropriately, INTECH expects that there will be periods of underperformance relative to the benchmark. On an occasional basis, INTECH makes changes to its mathematical investment process. These changes may result in changes to the portfolio, might not provide the intended results, and may adversely impact the Fund’s performance.

Portfolio Turnover Risk. Increased portfolio turnover may result in higher costs, which may have a negative effect on the Fund’s performance. In addition, higher portfolio turnover may result in the acceleration of capital gains and the recognition of greater levels of short-term capital gains, which are taxed at ordinary federal income tax rates when distributed to shareholders.

Securities Lending Risk. The Fund may seek to earn additional income through lending its securities to certain qualified broker-dealers and institutions. There is the risk that when portfolio securities are lent, the securities may not be returned on a timely basis, and the Fund may experience delays and costs in recovering the security or gaining access to the collateral provided to the Fund to collateralize the loan. If the Fund is unable to recover a security on loan, the Fund may use the collateral to purchase replacement securities in the market. There is a risk that the value of the collateral could decrease below the cost of the replacement security by the time the replacement investment is made, resulting in a loss to the Fund.

An investment in the Fund is not a bank deposit and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency.

PERFORMANCE INFORMATION

The following information provides some indication of the risks of investing in the Fund by showing how the Fund’s performance has varied over time. Class T Shares (formerly named Class J Shares, the initial share class) of the Fund commenced operations with the Fund’s inception. Class A Shares, Class C Shares, Class S Shares, and Class I Shares of the Fund commenced operations on July 6, 2009.

• The performance shown for Class T Shares is calculated using the fees and expenses of Class T Shares in effect during the periods shown, net of any applicable fee and expense limitations or waivers.
• The performance shown for Class A Shares, Class C Shares, and Class S Shares for periods prior to July 6, 2009, reflects the performance of the Fund’s former Class J Shares, calculated using the fees and expenses of each respective share class, without the effect of any fee and expense limitations or waivers.
• The performance shown for Class I Shares for periods prior to July 6, 2009, reflects the performance of the Fund’s former Class J Shares, calculated using the fees and expenses of Class J Shares, net of any applicable fee and expense limitations or waivers.

If Class A Shares, Class C Shares, Class S Shares, and Class I Shares of the Fund had been available during periods prior to July 6, 2009, the performance shown for each respective share class may have been different. The performance shown for periods following the Fund’s commencement of Class A Shares, Class C Shares, Class S Shares, and Class I Shares reflects the fees and expenses of each respective share class, net of any applicable fee and expense limitations or waivers.

The bar chart depicts the change in performance from year to year during the periods indicated. The bar chart figures do not include any applicable sales charges that an investor may pay when they buy or sell Class A Shares or Class C Shares of the Fund. If sales charges were included, the returns would be lower. The table compares the Fund’s average annual returns for the periods indicated to a broad-based securities market index. The index is not actively managed and is not available for direct investment. All figures assume reinvestment of dividends and distributions. For certain periods, the Fund’s performance reflects the effect of expense waivers. Without the effect of these expense waivers, the performance shown would have been lower.

The Fund’s past performance (before and after taxes) does not necessarily indicate how it will perform in the future. Updated performance information is available at janus.com/advisor/mutual-funds or by calling 1-877-335-2687.

Annual Total Returns for Class T Shares (calendar year-end)

Best Quarter:  Second Quarter 2009  14.79%          Worst Quarter:  Fourth Quarter 2008  −21.49%

The Fund’s year-to-date return as of the calendar quarter ended September 30, 2013 was 21.68%.

Average Annual Total Returns (periods ended 12/31/12)

Average Annual Total Returns INTECH U.S. Core Fund Class A, C, S, I, T Shares	Column	Label		1 Year	5 Years	Since Inception	Inception Date
Class T Return Before Taxes	Class T Shares	Return Before Taxes		14.62%	1.75%	8.47%	Feb. 28, 2003
Class T Return After Taxes on Distributions	Class T Shares	Return After Taxes on Distributions		14.38%	1.54%	7.79%	Feb. 28, 2003
Class T Return After Taxes on Distributions and Sale of Fund Shares	Class T Shares	Return After Taxes on Distributions and Sale of Fund Shares		9.83%	1.45%	7.32%	Feb. 28, 2003
Class A Return Before Taxes	Class A Shares	Return Before Taxes	[1]	7.97%	0.36%	7.55%	Feb. 28, 2003
Class C Return Before Taxes	Class C Shares	Return Before Taxes	[2]	12.46%	0.79%	7.39%	Feb. 28, 2003
Class S Return Before Taxes	Class S Shares	Return Before Taxes		14.33%	1.40%	8.01%	Feb. 28, 2003
Class I Return Before Taxes	Class I Shares	Return Before Taxes		14.80%	1.75%	8.47%	Feb. 28, 2003
S&P 500® Index (reflects no deduction for expenses, fees, or taxes)		S&P 500® Index		16.00%	1.66%	7.68%	Feb. 28, 2003

The Standard & Poor’s (“S&P”) 500^® Index is a commonly recognized, market-capitalization weighted index of 500 widely held equity securities, designed to measure broad U.S. equity performance. This index is used to calculate the performance fee adjustment.

After-tax returns are calculated using distributions for the Fund’s Class T Shares (formerly named Class J Shares, the initial share class). After-tax returns are calculated using the historically highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes. Actual after-tax returns depend on your individual tax situation and may differ from those shown in the preceding table. The after-tax return information shown above does not apply to Fund shares held through a tax-deferred account, such as a 401(k) plan or an IRA.

After-tax returns are only shown for Class T Shares of the Fund. After-tax returns for the other classes of Shares will vary from those shown for Class T Shares due to varying sales charges (as applicable), fees, and expenses among the classes.

[1] Calculated assuming maximum permitted sales loads.

[2] The one year return is calculated to include the contingent deferred sales charge.

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Janus Global Bond Fund | Class A, C, S, I, N, T Shares

FUND SUMMARY

Janus Global Bond Fund

INVESTMENT OBJECTIVE

Janus Global Bond Fund seeks total return, consistent with preservation of capital.

FEES AND EXPENSES OF THE FUND

This table describes the fees and expenses that you may pay if you buy and hold Shares of the Fund. Each share class has different expenses, but represents an investment in the same Fund.

For Class A Shares, you may qualify for sales charge discounts if you and your family invest, or agree to invest in the future, at least $50,000 in the Fund or in other Janus mutual funds. More information about these and other discounts, as well as eligibility requirements for each share class, is available from your financial professional and in the “Purchases” section on page 64 of the Fund’s Prospectus and in the “Purchases” section on page 70 of the Fund’s Statement of Additional Information.

SHAREHOLDER FEES
(fees paid directly from your investment)

Shareholder Fees Janus Global Bond Fund Class A, C, S, I, N, T Shares	Class A	Class C	Class S	Class I	Class N	Class T
Shareholder Fees Column [Text]	Class A	Class C	Class S	Class I	Class N	Class T
Maximum Sales Charge (load) Imposed on Purchases (as a percentage of offering price)	4.75%	none	none	none	none	none
Maximum Deferred Sales Charge (load) (as a percentage of the lower of original purchase price or redemption proceeds)	none	1.00%	none	none	none	none

ANNUAL FUND OPERATING EXPENSES
(expenses that you pay each year as a percentage of the value of your investment)

Annual Fund Operating Expenses Janus Global Bond Fund Class A, C, S, I, N, T Shares		Class A	Class C	Class S	Class I	Class N	Class T
Operating Expenses Column [Text]		Class A	Class C	Class S	Class I	Class N	Class T
Management Fees		0.60%	0.60%	0.60%	0.60%	0.60%	0.60%
Distribution/Service (12b-1) Fees		0.25%	1.00%	0.25%	none	none	none
Other Expenses	[1]	0.24%	0.25%	0.45%	0.20%	0.20%	0.45%
Total Annual Fund Operating Expenses	[2]	1.09%	1.85%	1.30%	0.80%	0.80%	1.05%
Fee Waiver	[2]	0.06%	0.08%	0.05%	0.05%	0.05%	0.05%
Total Annual Fund Operating Expenses After Fee Waiver	[2]	1.03%	1.77%	1.25%	0.75%	0.75%	1.00%

EXAMPLE:

The following Example is based on expenses without waivers. The Example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds.

The Example assumes that you invest $10,000 in the Fund for the time periods indicated and reinvest all dividends and distributions. The Example also assumes that your investment has a 5% return each year and that the Fund’s operating expenses without waivers or recoupments (if applicable) remain the same. Although your actual costs may be higher or lower, based on these assumptions your costs would be:

If Shares are redeemed:

Expense Example Janus Global Bond Fund Class A, C, S, I, N, T Shares (USD $)	Expense Example, By Year, Column [Text]	1 Year	3 Years	5 Years	10 Years
Class A	Class A Shares	581	805	1,047	1,741
Class C	Class C Shares	288	582	1,001	2,169
Class S	Class S Shares	132	412	713	1,568
Class I	Class I Shares	82	255	444	990
Class N	Class N Shares	82	255	444	990
Class T	Class T Shares	107	334	579	1,283

If Shares are not redeemed:

Expense Example, No Redemption Janus Global Bond Fund Class A, C, S, I, N, T Shares (USD $)	Expense Example, No Redemption, By Year, Column [Text]	1 Year	3 Years	5 Years	10 Years
Class A	Class A Shares	581	805	1,047	1,741
Class C	Class C Shares	188	582	1,001	2,169
Class S	Class S Shares	132	412	713	1,568
Class I	Class I Shares	82	255	444	990
Class N	Class N Shares	82	255	444	990
Class T	Class T Shares	107	334	579	1,283

Portfolio Turnover: 

The Fund pays transaction costs, such as commissions, when it buys and sells securities (or “turns over” its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when Fund shares are held in a taxable account. These costs, which are not reflected in annual fund operating expenses or in the Example, affect the Fund’s performance. During the most recent fiscal year, the Fund’s portfolio turnover rate was 182% of the average value of its portfolio.

PRINCIPAL INVESTMENT STRATEGIES

The Fund pursues its investment objective by investing, under normal circumstances, at least 80% of its net assets in bonds. Bonds include, but are not limited to, corporate bonds, government notes and bonds, convertible bonds, mortgage-backed securities, and zero-coupon bonds. The Fund invests in corporate debt securities of issuers in a number of different countries, which may include the United States. The Fund invests in securities of issuers that are economically tied to developed and emerging market countries. The Fund may invest across all fixed-income sectors, including U.S. and non-U.S. government securities. The Fund’s investments may be denominated in local currency or U.S. dollar-denominated. The Fund may invest in debt securities with a range of maturities from short- to long-term. The Fund may invest up to 35% of its net assets in high-yield/high-risk debt securities. The Fund may also invest in preferred and common stock, money market instruments, municipal bonds, commercial and residential mortgage-backed securities, asset-backed securities, other securitized and structured debt products, private placements, and other investment companies, including exchange-traded funds (“ETFs”). The Fund may also invest in bank loans, euro-denominated obligations, buy backs or dollar rolls, when-issued securities, and reverse repurchase agreements. Due to the nature of securities in which the Fund invests, it may have relatively high portfolio turnover compared to other funds.

In addition, the Fund may invest its assets in derivatives, which are instruments that have a value derived from, or directly linked to, an underlying asset, such as equity securities, fixed-income securities, commodities, currencies, interest rates, or market indices, as substitutes for securities in which the Fund invests. The Fund has invested in and is expected to continue to invest in collateralized forward foreign currency exchange contracts, futures, options, and swaps (including interest rate swaps, total return swaps, and credit default swaps) for hedging purposes (to offset risks associated with an investment, currency exposure, or market conditions) and to increase or decrease the Fund’s exposure to a particular market, to manage or adjust the risk profile of the Fund related to an investment or currency exposure, to adjust its currency exposure relative to its benchmark index, and to earn income and enhance returns. In particular, the Fund may use interest rate futures to manage portfolio risk. The Fund’s exposure to derivatives will vary, is not limited to those derivatives listed, and could be significant at times. For purposes of meeting its 80% investment policy, the Fund may include derivatives that have characteristics similar to the securities in which the Fund may directly invest.

In addition to considering economic factors such as the effect of interest rates on the Fund’s investments, the portfolio managers apply a “bottom up” approach in choosing investments. This means that the portfolio managers look at income-producing securities one at a time to determine if a security is an attractive investment opportunity and if it is consistent with the Fund’s investment policies.

The Fund may lend portfolio securities on a short-term or long-term basis, in an amount equal to up to 1/3 of its total assets as determined at the time of the loan origination.

PRINCIPAL INVESTMENT RISKS

Although the Fund may be less volatile than funds that invest most of their assets in common stocks, the Fund’s returns and yields will vary, and you could lose money.

Fixed-Income Securities Risk. The Fund invests in a variety of fixed-income securities. Typically, the values of fixed-income securities change inversely with prevailing interest rates. Therefore, a fundamental risk of fixed-income securities is interest rate risk, which is the risk that the value of such securities will generally decline as prevailing interest rates rise, which may cause the Fund’s net asset value to likewise decrease. How specific fixed-income securities may react to changes in interest rates will depend on the specific characteristics of each security. Fixed-income securities are also subject to credit risk, prepayment risk, valuation risk, and liquidity risk. Credit risk is the risk that the credit strength of an issuer of a fixed-income security will weaken and/or that the issuer will be unable to make timely principal and interest payments and that the security may go into default. Prepayment risk is the risk that during periods of falling interest rates, certain fixed-income securities with higher interest rates, such as mortgage- and asset-backed securities, may be prepaid by their issuers thereby reducing the amount of interest payments. Valuation risk is the risk that one or more of the fixed-income securities in which the Fund invests are priced differently than the value realized upon such security’s sale. In times of market instability, valuation may be more difficult. Liquidity risk is the risk that fixed-income securities may be difficult or impossible to sell at the time that the portfolio managers would like or at the price the portfolio managers believe the security is currently worth.

Foreign Exposure Risk. The Fund normally has significant exposure to foreign markets as a result of its investments in foreign securities, including investments in emerging markets, which can be more volatile than the U.S. markets. As a result, its returns and net asset value may be affected to a large degree by fluctuations in currency exchange rates or political or economic conditions in a particular country. In some foreign markets, there may not be protection against failure by other parties to complete transactions. It may not be possible for the Fund to repatriate capital, dividends, interest, and other income from a particular country or governmental entity. In addition, a market swing in one or more countries or regions where the Fund has invested a significant amount of its assets may have a greater effect on the Fund’s performance than it would in a more geographically diversified portfolio. The Fund’s investments in emerging market countries may involve risks greater than, or in addition to, the risks of investing in more developed countries. To the extent the Fund invests in foreign debt securities, such investments are sensitive to changes in interest rates. Additionally, investments in securities of foreign governments involve the risk that a foreign government may not be willing or able to pay interest or repay principal when due.

Eurozone Risk. A number of countries in the European Union (“EU”) have experienced severe economic and financial difficulties. As a result, financial markets in the EU have been subject to extreme volatility and declines in asset values and liquidity. Responses to these financial problems by European governments, central banks, and others, including austerity measures and reforms, may not work, may result in social unrest, and may limit future growth and economic recovery or have other unintended consequences. Further defaults or restructurings by governments and others of their debt could have additional adverse effects on economies, financial markets, and asset valuations around the world. To the extent that the Fund has exposure to European markets or to transactions tied to the value of the euro, these events could negatively affect the value and liquidity of the Fund’s investments.

Emerging Markets Risk. The risks of foreign investing mentioned above are heightened when investing in emerging markets. Emerging markets securities involve a number of additional risks, which may result from less government supervision and regulation of business and industry practices (including the potential lack of strict finance and accounting controls and standards), stock exchanges, brokers, and listed companies, making these investments potentially more volatile in price and less liquid than investments in developed securities markets, resulting in greater risk to investors. There is a risk in developing countries that a future economic or political crisis could lead to price controls, forced mergers of companies, expropriation or confiscatory taxation, imposition or enforcement of foreign ownership limits, seizure, nationalization, or creation of government monopolies, any of which may have a detrimental effect on the Fund’s investments. In addition, the Fund’s investments may be denominated in foreign currencies and therefore, changes in the value of a country’s currency compared to the U.S. dollar may affect the value of the Fund’s investments. To the extent that the Fund invests a significant portion of its assets in the securities of issuers in or companies of a single country or region, it is more likely to be impacted by events or conditions affecting that country or region, which could have a negative impact on the Fund’s performance. Some of the risks of investing directly in foreign and emerging market securities may be reduced when the Fund invests indirectly in foreign securities through various other investment vehicles including derivatives, which also involve other risks. As of June 30, 2013, approximately 4.2% of the Fund’s investments were in emerging markets.

Mortgage-Backed Securities Risk. Mortgage-backed securities are classified generally as either commercial mortgage-backed securities or residential mortgage-backed securities, each of which is subject to certain specific risks. Mortgage-backed securities tend to be more sensitive to changes in interest rates than other types of debt securities. Investments in mortgage-backed securities are subject to both extension risk, where borrowers extend the duration of their mortgages in times of rising interest rates, and prepayment risk, where borrowers pay off their mortgages sooner than expected in times of declining interest rates. These risks may reduce the Fund’s returns. In addition, investments in mortgage-backed securities, including those comprised of subprime mortgages, may be subject to a higher degree of credit risk, valuation risk, and liquidity risk than various other types of fixed-income securities.

Sovereign Debt Risk. The Fund may invest in U.S. and foreign government debt securities (“sovereign debt”). Investments in U.S. sovereign debt are considered low risk. However, investments in non-U.S. sovereign debt can involve a high degree of risk, including the risk that the governmental entity that controls the repayment of sovereign debt may not be willing or able to repay the principal and/or to pay the interest on its sovereign debt in a timely manner. A sovereign debtor’s willingness or ability to satisfy its debt obligation may be affected by various factors including, but not limited to, its cash flow situation, the extent of its foreign currency reserves, the availability of foreign exchange when a payment is due, and the relative size of its debt position in relation to its economy as a whole. In the event of default, there may be limited or no legal remedies for collecting sovereign debt and there may be no bankruptcy proceedings through which the Fund may collect all or part of the sovereign debt that a governmental entity has not repaid.

High-Yield/High-Risk Bond Risk. High-yield/high-risk bonds (also known as “junk” bonds) may be more sensitive than other types of bonds to economic changes, political changes, or adverse developments specific to the company that issued the bond, which may adversely affect their value.

Bank Loan Risk. Bank loans are obligations of companies or other entities entered into in connection with recapitalizations, acquisitions, and refinancings. The Fund’s investments in bank loans are generally acquired as a participation interest in, or assignment of, loans originated by a lender or other financial institution. These investments may include institutionally-traded floating and fixed-rate debt securities. Participation interests and assignments involve credit, interest rate, and liquidity risk. In addition, the bank loans underlying these securities often involve borrowers with low credit ratings whose financial conditions are troubled or uncertain, including companies that are highly leveraged or in bankruptcy proceedings.

Exchange-Traded Funds Risk. The Fund may purchase shares of exchange-traded funds (“ETFs”) to gain exposure to a particular portion of the market. ETFs are pooled investment vehicles, which may be managed or unmanaged, that generally seek to track the performance of a specific index. ETFs are traded on an exchange at market prices that may vary from the net asset value of their underlying investments. When the Fund invests in an ETF, in addition to directly bearing the expenses associated with its own operations, it will bear a pro rata portion of the ETF’s expenses. ETFs have certain inherent risks generally associated with investments in a portfolio of securities in which the ETF is invested, including the risk that the general level of stock prices may decline, thereby adversely affecting the value of each unit of the ETF. ETFs also involve the risk that an active trading market for an ETF’s shares may not develop or be maintained.

Derivatives Risk. Derivatives can be highly volatile and involve risks in addition to the risks of the underlying referenced securities. Gains or losses from a derivative investment can be substantially greater than the derivative’s original cost, and can therefore involve leverage. Leverage may cause the Fund to be more volatile than if it had not used leverage. Derivatives can be complex instruments and may involve analysis that differs from that required for other investment types used by the Fund. If the value of a derivative does not correlate well with the particular market or other asset class to which the derivative is intended to provide exposure, the derivative may not produce the anticipated result. Derivatives can also reduce the opportunity for gain or result in losses by offsetting positive returns in other investments. Derivatives can be less liquid than other types of investments and entail the risk that the counterparty will default on its payment obligations. If the counterparty to a derivative transaction defaults, the Fund would risk the loss of the net amount of the payments that it contractually is entitled to receive. To the extent the Fund enters into short derivative positions, the Fund may be exposed to risks similar to those associated with short sales, including the risk that the Fund’s losses are theoretically unlimited.

Portfolio Turnover Risk. Increased portfolio turnover may result in higher costs, which may have a negative effect on the Fund’s performance. In addition, higher portfolio turnover may result in the acceleration of capital gains and the recognition of greater levels of short-term capital gains, which are taxed at ordinary federal income tax rates when distributed to shareholders.

Securities Lending Risk. The Fund may seek to earn additional income through lending its securities to certain qualified broker-dealers and institutions. There is the risk that when portfolio securities are lent, the securities may not be returned on a timely basis, and the Fund may experience delays and costs in recovering the security or gaining access to the collateral provided to the Fund to collateralize the loan. If the Fund is unable to recover a security on loan, the Fund may use the collateral to purchase replacement securities in the market. There is a risk that the value of the collateral could decrease below the cost of the replacement security by the time the replacement investment is made, resulting in a loss to the Fund.

An investment in the Fund is not a bank deposit and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency.

PERFORMANCE INFORMATION

The following information provides some indication of the risks of investing in the Fund by showing how the Fund’s performance has varied over time. Class A Shares, Class C Shares, Class S Shares, Class I Shares, and Class T Shares of the Fund commenced operations with the Fund’s inception. Class N Shares of the Fund commenced operations on October 28, 2013.

• The performance shown for Class A Shares, Class C Shares, Class S Shares, Class I Shares, and Class T Shares is calculated using the fees and expenses of each respective share class, net of any applicable fee and expense limitations or waivers.
• The performance shown for Class N Shares for periods prior to December 31, 2012, reflects the performance of the Fund’s Class I Shares, calculated using the fees and expenses of Class N Shares, without the effect of any fee and expense limitations or waivers. If Class N Shares of the Fund had been available during periods prior to December 31, 2012, the performance shown may have been different.

The bar chart depicts the change in performance from year to year during the periods indicated. The bar chart figures do not include any applicable sales charges that an investor may pay when they buy or sell Class A Shares or Class C Shares of the Fund. If sales charges were included, the returns would be lower. The table compares the Fund’s average annual returns for the periods indicated to broad-based securities market indices. The indices are not actively managed and are not available for direct investment. All figures assume reinvestment of dividends and distributions. For certain periods, the Fund’s performance reflects the effect of expense waivers. Without the effect of these expense waivers, the performance shown would have been lower.

The Fund’s past performance (before and after taxes) does not necessarily indicate how it will perform in the future. Updated performance information is available at janus.com/advisor/mutual-funds or by calling 1-877-335-2687.

Annual Total Returns for Class I Shares (calendar year-end)

Best Quarter:  Third Quarter 2012  4.26%          Worst Quarter:  Fourth Quarter 2012  0.32%

The Fund’s year-to-date return as of the calendar quarter ended September 30, 2013 was −3.22%.

Average Annual Total Returns (periods ended 12/31/12)

Average Annual Total Returns Janus Global Bond Fund Class A, C, S, I, N, T Shares	Column	Label		1 Year	Since Inception	Inception Date
Class I Return Before Taxes	Class I Shares	Return Before Taxes		8.28%	7.44%	Dec. 28, 2010
Class I Return After Taxes on Distributions	Class I Shares	Return After Taxes on Distributions		6.39%	5.81%	Dec. 28, 2010
Class I Return After Taxes on Distributions and Sale of Fund Shares	Class I Shares	Return After Taxes on Distributions and Sale of Fund Shares		5.50%	5.43%	Dec. 28, 2010
Class A Return Before Taxes	Class A Shares	Return Before Taxes	[1]	2.91%	4.66%	Dec. 28, 2010
Class C Return Before Taxes	Class C Shares	Return Before Taxes	[2]	6.19%	6.48%	Dec. 28, 2010
Class S Return Before Taxes	Class S Shares	Return Before Taxes		7.81%	7.04%	Dec. 28, 2010
Class N Return Before Taxes	Class N Shares	Return Before Taxes		7.87%	7.04%	Dec. 28, 2010
Class T Return Before Taxes	Class T Shares	Return Before Taxes		8.03%	7.24%	Dec. 28, 2010
Barclays Global Aggregate Bond Index (reflects no deduction for expenses, fees, or taxes)		Barclays Global Aggregate Bond Index		4.32%	5.74%	Dec. 28, 2010
Barclays Global Aggregate Corporate Bond Index (reflects no deduction for expenses, fees, or taxes)		Barclays Global Aggregate Corporate Bond Index		11.21%	8.59%	Dec. 28, 2010

After-tax returns are calculated using the historically highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes. Actual after-tax returns depend on your individual tax situation and may differ from those shown in the preceding table. The after-tax return information shown above does not apply to Fund shares held through a tax-deferred account, such as a 401(k) plan or an IRA.

After-tax returns are only shown for Class I Shares of the Fund. After-tax returns for the other classes of Shares will vary from those shown for Class I Shares due to varying sales charges (as applicable), fees, and expenses among the classes.

[1] Other Expenses are based on the estimated expenses that the Fund expects to incur.

[2] Janus Capital has contractually agreed to waive its investment advisory fee and/or reimburse Fund expenses to the extent that the Fund’s total annual fund operating expenses (excluding the distribution and shareholder servicing fees – applicable to Class A Shares, Class C Shares, and Class S Shares; administrative services fees payable pursuant to the Transfer Agency Agreement; brokerage commissions; interest; dividends; taxes; acquired fund fees and expenses; and extraordinary expenses) exceed 0.75% until at least November 1, 2014. The contractual waiver may be terminated or modified prior to this date only at the discretion of the Board of Trustees. For a period of three years subsequent to the Fund’s commencement of operations (December 28, 2010) or until the Fund’s assets exceed the first breakpoint in the investment advisory fee schedule, whichever occurs first, Janus Capital may recover from the Fund fees and expenses previously waived or reimbursed, which could then be considered a deferral, if the Fund’s expense ratio, including recovered expenses, falls below the expense limit.

[1] Calculated assuming maximum permitted sales loads.

[2] The one year return is calculated to include the contingent deferred sales charge.

XML

Perkins Small Cap Value Fund | Class L Shares

FUND SUMMARY

Perkins Small Cap Value Fund

INVESTMENT OBJECTIVE

Perkins Small Cap Value Fund seeks capital appreciation.

FEES AND EXPENSES OF THE FUND

This table describes the fees and expenses that you may pay if you buy and hold Shares of the Fund.

ANNUAL FUND OPERATING EXPENSES
(expenses that you pay each year as a percentage of the value of your investment)

Annual Fund Operating Expenses	Perkins Small Cap Value Fund Class L Shares Class L
Operating Expenses Column [Text]	Class L
Management Fees (may adjust up or down)	0.56%
Other Expenses	0.27%
Total Annual Fund Operating Expenses	0.83%

EXAMPLE:

The Example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds.

The Example assumes that you invest $10,000 in the Fund for the time periods indicated, reinvest all dividends and distributions, and then redeem all of your Shares at the end of each period. The Example also assumes that your investment has a 5% return each year and that the Fund’s operating expenses remain the same. Although your actual costs may be higher or lower, based on these assumptions your costs would be:

Expense Example (USD $)	Expense Example, By Year, Column [Text]	1 Year	3 Years	5 Years	10 Years
Perkins Small Cap Value Fund Class L Shares Class L	Class L Shares	85	265	460	1,025

Portfolio Turnover:

The Fund pays transaction costs, such as commissions, when it buys and sells securities (or “turns over” its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when Fund shares are held in a taxable account. These costs, which are not reflected in annual fund operating expenses or in the Example, affect the Fund’s performance. During the most recent fiscal year, the Fund’s portfolio turnover rate was 60% of the average value of its portfolio.

PRINCIPAL INVESTMENT STRATEGIES

The Fund pursues its investment objective by investing primarily in the common stocks of small companies whose stock prices are believed to be undervalued by the Fund’s portfolio managers. The Fund invests, under normal circumstances, at least 80% of its net assets in equity securities of small companies whose market capitalization, at the time of initial purchase, is less than the 12-month average of the maximum market capitalization for companies included in the Russell 2000^® Value Index. This average is updated monthly. The market capitalizations within the index will vary, but as of June 30, 2013, they ranged from approximately $23 million to $5.6 billion. The Fund may also invest in foreign equity and debt securities, which may include investments in emerging markets. The Fund may invest, under normal circumstances, up to 20% of its net assets in securities of companies having market capitalizations outside of the aforementioned market capitalization ranges. In addition, when the portfolio managers believe that market conditions are unfavorable for investing, or when they are otherwise unable to locate attractive investment opportunities, the Fund may invest up to 20% of its net assets in cash or similar investments.

The Fund’s securities selection focuses on companies that are out of favor with markets or have not yet been discovered by the broader investment community. The Fund’s portfolio managers generally look for companies with:

• strong balance sheets and solid recurring free cash flows
• attractive relative and absolute valuation ratios or that have underperformed recently
• favorable reward to risk characteristics

The portfolio managers’ philosophy is to weigh a security’s downside risk before considering its upside potential, which may help provide an element of capital preservation.

PRINCIPAL INVESTMENT RISKS

The biggest risk is that the Fund’s returns will vary, and you could lose money. The Fund is designed for long-term investors seeking an equity portfolio, including common stocks. Common stocks tend to be more volatile than many other investment choices.

Value Investing Risk. Because different types of stocks tend to shift in and out of favor depending on market and economic conditions, “value” stocks may perform differently than other types of stocks and from the market as a whole, and can continue to be undervalued by the market for long periods of time. It is also possible that a value stock will never appreciate to the extent expected by the portfolio managers. When the Fund’s investments in cash or similar investments increase due to a lack of favorable investment opportunities or other extraordinary factors, the Fund may not participate in market advances or declines to the same extent that it would if the Fund had been fully invested.

Market Risk. The value of the Fund’s portfolio may decrease if the value of an individual company or security, or multiple companies or securities, in the portfolio decreases or if the portfolio managers’ belief about a company’s intrinsic worth is incorrect. Further, regardless of how well individual companies or securities perform, the value of the Fund’s portfolio could also decrease if there are deteriorating economic or market conditions. It is important to understand that the value of your investment may fall, sometimes sharply, in response to changes in the market, and you could lose money.

Small-Sized Companies Risk. The Fund’s investments in securities issued by small-sized companies, which can include smaller, start-up companies offering emerging products or services, may involve greater risks than are customarily associated with larger, more established companies. Securities issued by small-sized companies tend to be more volatile and somewhat more speculative than securities issued by larger or more established companies and may underperform as compared to the securities of larger companies.

Real Estate Securities Risk. The Fund’s performance may be affected by the risks associated with investments in real estate-related companies. The value of real estate-related companies’ securities is sensitive to changes in real estate values and rental income, property taxes, interest rates, tax and regulatory requirements, supply and demand, and the management skill and creditworthiness of the company. Investments in real estate investment trusts (“REITs”) involve the same risks as other real estate investments. In addition, a REIT could fail to qualify for tax-free pass-through of its income under the Internal Revenue Code or fail to maintain its exemption from registration under the Investment Company Act of 1940, as amended, which could produce adverse economic consequences for the REIT and its investors, including the Fund.

An investment in the Fund is not a bank deposit and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency.

PERFORMANCE INFORMATION

The following information provides some indication of the risks of investing in the Fund by showing how the Fund’s performance has varied over time. The performance shown for periods following April 21, 2003, reflects the fees and expenses of Class L Shares (formerly named Institutional Shares), net of any applicable fee and expense limitations or waivers. For the periods prior to April 21, 2003, the performance shown for Class L Shares reflects the historical performance of Berger Small Cap Value Fund – Institutional Shares (as a result of a prior reorganization of Berger Small Cap Value Fund – Institutional Shares into the Fund’s Class L Shares).

The bar chart depicts the change in performance from year to year during the periods indicated. The table compares the Fund’s average annual returns for the periods indicated to a broad-based securities market index. The index is not actively managed and is not available for direct investment. All figures assume reinvestment of dividends and distributions. For certain periods, the Fund’s performance reflects the effect of expense waivers. Without the effect of these expense waivers, the performance shown would have been lower.

The Fund’s past performance (before and after taxes) does not necessarily indicate how it will perform in the future. Updated performance information is available at janus.com/advisor/mutual-funds or by calling 1-877-335-2687.

Annual Total Returns for Class L Shares (calendar year-end)

Best Quarter:  Second Quarter 2009  23.27%          Worst Quarter:  Fourth Quarter 2008  −18.78%

The Fund’s year-to-date return as of the calendar quarter ended September 30, 2013 was 18.62%.

Average Annual Total Returns (periods ended 12/31/12)

Average Annual Total Returns Perkins Small Cap Value Fund Class L Shares	Column	Label		1 Year	5 Years	10 Years
Class L Return Before Taxes	Class L Shares	Return Before Taxes		9.25%	6.05%	10.26%
Class L Return After Taxes on Distributions	Class L Shares	Return After Taxes on Distributions		8.35%	4.80%	8.31%
Class L Return After Taxes on Distributions and Sale of Fund Shares	Class L Shares	Return After Taxes on Distributions and Sale of Fund Shares	[1]	7.22%	4.84%	8.43%
Russell 2000® Value Index (reflects no deduction for expenses, fees, or taxes)		Russell 2000® Value Index		18.05%	3.55%	9.50%

The Russell 2000^® Value Index measures the performance of those Russell 2000^® companies with lower price-to-book ratios and lower forecasted growth values. This index is used to calculate the performance fee adjustment.

After-tax returns are calculated using distributions for the Fund’s Class L Shares (formerly named Institutional Shares) for the periods following April 21, 2003; and for Berger Small Cap Value Fund – Institutional Shares for periods prior to April 21, 2003. If Class L Shares of the Fund had been available during these earlier periods, distributions may have been different and thus, after-tax returns may have been different from those shown. After-tax returns are calculated using the historically highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes. Actual after-tax returns depend on your individual tax situation and may differ from those shown in the preceding table. The after-tax return information shown above does not apply to Fund shares held through a tax-deferred account, such as a 401(k) plan or an IRA.

[1] If the Fund incurs a loss, which generates a tax benefit, the Return After Taxes on Distributions and Sale of Fund Shares may exceed the Fund’s other return figures.

XML

Perkins Mid Cap Value Fund | Class L Shares

FUND SUMMARY

Perkins Mid Cap Value Fund

INVESTMENT OBJECTIVE

Perkins Mid Cap Value Fund seeks capital appreciation.

FEES AND EXPENSES OF THE FUND

This table describes the fees and expenses that you may pay if you buy and hold Shares of the Fund.

ANNUAL FUND OPERATING EXPENSES
(expenses that you pay each year as a percentage of the value of your investment)

Annual Fund Operating Expenses	Perkins Mid Cap Value Fund Class L Shares Class L
Operating Expenses Column [Text]	Class L
Management Fees (may adjust up or down)	0.48%
Other Expenses	0.29%
Total Annual Fund Operating Expenses	0.77%

EXAMPLE:

The Example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds.

The Example assumes that you invest $10,000 in the Fund for the time periods indicated, reinvest all dividends and distributions, and then redeem all of your Shares at the end of each period. The Example also assumes that your investment has a 5% return each year and that the Fund’s operating expenses remain the same. Although your actual costs may be higher or lower, based on these assumptions your costs would be:

Expense Example (USD $)	Expense Example, By Year, Column [Text]	1 Year	3 Years	5 Years	10 Years
Perkins Mid Cap Value Fund Class L Shares Class L	Class L Shares	79	246	428	954

Portfolio Turnover: 

The Fund pays transaction costs, such as commissions, when it buys and sells securities (or “turns over” its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when Fund shares are held in a taxable account. These costs, which are not reflected in annual fund operating expenses or in the Example, affect the Fund’s performance. During the most recent fiscal year, the Fund’s portfolio turnover rate was 60% of the average value of its portfolio.

PRINCIPAL INVESTMENT STRATEGIES

The Fund pursues its investment objective by investing primarily in common stocks selected for their capital appreciation potential. The Fund primarily invests in the common stocks of mid-sized companies whose stock prices the portfolio managers believe to be undervalued. The Fund invests, under normal circumstances, at least 80% of its net assets in equity securities of companies whose market capitalization falls, at the time of purchase, within the 12-month average of the capitalization range of the Russell Midcap^® Value Index. This average is updated monthly. The market capitalizations within the index will vary, but as of June 30, 2013, they ranged from approximately $487 million to $30.3 billion. The Fund may also invest in foreign equity and debt securities, which may include investments in emerging markets. The Fund may invest, under normal circumstances, up to 20% of its net assets in securities of companies having market capitalizations outside of the aforementioned market capitalization ranges. In addition, when the portfolio managers believe that market conditions are unfavorable for investing, or when they are otherwise unable to locate attractive investment opportunities, the Fund may invest up to 20% of its net assets in cash or similar investments.

The Fund focuses on companies that have fallen out of favor with the market or that appear to be temporarily misunderstood by the investment community. The Fund’s portfolio managers generally look for companies with:

• strong balance sheets and solid recurring free cash flows
• attractive relative and absolute valuation ratios or that have underperformed recently
• favorable reward to risk characteristics

The Fund may invest in equity and debt securities of real estate-related companies. Such companies may include those in the real estate industry or real estate-related industries. These securities may include common stocks, preferred stocks, and other equity securities, including, but not limited to, mortgage-backed securities, real estate-backed securities, securities of real estate investment trusts (“REITs”) and similar REIT-like entities. A REIT is a trust that invests in real estate-related projects, such as properties, mortgage loans, and construction loans. REITs are generally categorized as equity, mortgage, or hybrid REITs. A REIT may be listed on an exchange or traded over-the-counter.

The Fund may also invest its assets in derivatives, which are instruments that have a value derived from, or directly linked to, an underlying asset, such as equity securities, fixed-income securities, commodities, currencies, interest rates, or market indices. The Fund from time to time may buy and sell put and call options, particularly on market indices, for hedging purposes (to offset risks associated with an investment, currency exposure, or market conditions) and to enhance returns. The Fund’s exposure to derivatives will vary, is not limited to those derivatives listed, and could be significant at times. For purposes of meeting its 80% investment policy, the Fund may include derivatives that have characteristics similar to the securities in which the Fund may directly invest.

PRINCIPAL INVESTMENT RISKS

The biggest risk is that the Fund’s returns will vary, and you could lose money. The Fund is designed for long-term investors seeking an equity portfolio, including common stocks. Common stocks tend to be more volatile than many other investment choices.

Value Investing Risk. Because different types of stocks tend to shift in and out of favor depending on market and economic conditions, “value” stocks may perform differently than other types of stocks and from the market as a whole, and can continue to be undervalued by the market for long periods of time. It is also possible that a value stock will never appreciate to the extent expected by the portfolio managers. When the Fund’s investments in cash or similar investments increase due to a lack of favorable investment opportunities or other extraordinary factors, the Fund may not participate in market advances or declines to the same extent that it would if the Fund had been fully invested.

Market Risk. The value of the Fund’s portfolio may decrease if the value of an individual company or security, or multiple companies or securities, in the portfolio decreases or if the portfolio managers’ belief about a company’s intrinsic worth is incorrect. Further, regardless of how well individual companies or securities perform, the value of the Fund’s portfolio could also decrease if there are deteriorating economic or market conditions. It is important to understand that the value of your investment may fall, sometimes sharply, in response to changes in the market, and you could lose money.

Mid-Sized Companies Risk. The Fund’s investments in securities issued by mid-sized companies may involve greater risks than are customarily associated with larger, more established companies. Securities issued by mid-sized companies tend to be more volatile than securities issued by larger or more established companies and may underperform as compared to the securities of larger companies.

Real Estate Securities Risk. The Fund’s performance may be affected by the risks associated with investments in real estate-related companies. The value of real estate-related companies’ securities is sensitive to changes in real estate values and rental income, property taxes, interest rates, tax and regulatory requirements, supply and demand, and the management skill and creditworthiness of the company. Investments in REITs involve the same risks as other real estate investments. In addition, a REIT could fail to qualify for tax-free pass-through of its income under the Internal Revenue Code or fail to maintain its exemption from registration under the Investment Company Act of 1940, as amended, which could produce adverse economic consequences for the REIT and its investors, including the Fund.

Foreign Exposure Risk. The Fund may have exposure to foreign markets as a result of its investments in foreign securities, including investments in emerging markets, which can be more volatile than the U.S. markets. As a result, its returns and net asset value may be affected to a large degree by fluctuations in currency exchange rates or political or economic conditions in a particular country. In some foreign markets, there may not be protection against failure by other parties to complete transactions. It may not be possible for the Fund to repatriate capital, dividends, interest, and other income from a particular country or governmental entity. In addition, a market swing in one or more countries or regions where the Fund has invested a significant amount of its assets may have a greater effect on the Fund’s performance than it would in a more geographically diversified portfolio. To the extent the Fund invests in foreign debt securities, such investments are sensitive to changes in interest rates. Additionally, investments in securities of foreign governments involve the risk that a foreign government may not be willing or able to pay interest or repay principal when due.

Derivatives Risk. Derivatives can be highly volatile and involve risks in addition to the risks of the underlying referenced securities. Gains or losses from a derivative investment can be substantially greater than the derivative’s original cost, and can therefore involve leverage. Leverage may cause the Fund to be more volatile than if it had not used leverage. Derivatives can be complex instruments and may involve analysis that differs from that required for other investment types used by the Fund. If the value of a derivative does not correlate well with the particular market or other asset class to which the derivative is intended to provide exposure, the derivative may not produce the anticipated result. Derivatives can also reduce the opportunity for gain or result in losses by offsetting positive returns in other investments. Derivatives can be less liquid than other types of investments and entail the risk that the counterparty will default on its payment obligations. If the counterparty to a derivative transaction defaults, the Fund would risk the loss of the net amount of the payments that it contractually is entitled to receive. To the extent the Fund enters into short derivative positions, the Fund may be exposed to risks similar to those associated with short sales, including the risk that the Fund’s losses are theoretically unlimited.

An investment in the Fund is not a bank deposit and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency.

PERFORMANCE INFORMATION

The following information provides some indication of the risks of investing in the Fund by showing how the Fund’s performance has varied over time. The performance shown for periods following April 21, 2003, reflects the fees and expenses of Class L Shares (formerly named Institutional Shares), net of any applicable fee and expense limitations or waivers. The performance shown for Class L Shares for the periods from May 17, 2002 to April 17, 2003, reflects the historical performance of Berger Mid Cap Value Fund – Institutional Shares (as a result of a prior reorganization of Berger Mid Cap Value Fund – Institutional Shares into the Fund’s Class L Shares). For the periods prior to May 17, 2002, the performance shown reflects the historical performance of Berger Mid Cap Value Fund – Investor Shares.

The bar chart depicts the change in performance from year to year during the periods indicated. The table compares the Fund’s average annual returns for the periods indicated to a broad-based securities market index. The index is not actively managed and is not available for direct investment. All figures assume reinvestment of dividends and distributions. For certain periods, the Fund’s performance reflects the effect of expense waivers. Without the effect of these expense waivers, the performance shown would have been lower.

The Fund’s past performance (before and after taxes) does not necessarily indicate how it will perform in the future. Updated performance information is available at janus.com/advisor/mutual-funds or by calling 1-877-335-2687.

Annual Total Returns for Class L Shares (calendar year-end)

Best Quarter:  Second Quarter 2003  17.19%          Worst Quarter:  Fourth Quarter 2008  −19.56%

The Fund’s year-to-date return as of the calendar quarter ended September 30, 2013 was 17.54%.

Average Annual Total Returns (periods ended 12/31/12)

^[1]

Average Annual Total Returns Perkins Mid Cap Value Fund Class L Shares	Column	Label		1 Year	5 Years	10 Years	Since Inception of Predecessor Fund	Inception Date
Return Before Taxes Class L	Class L Shares	Return Before Taxes		10.47%	3.39%	10.39%	11.82%	Aug. 12, 1998
Return After Taxes on Distributions Class L	Class L Shares	Return After Taxes on Distributions		9.79%	2.72%	9.18%	10.40%	Aug. 12, 1998
Return After Taxes on Distributions and Sale of Fund Shares Class L	Class L Shares	Return After Taxes on Distributions and Sale of Fund Shares	[1]	7.72%	2.78%	8.84%	10.03%	Aug. 12, 1998
Russell Midcap® Value Index (reflects no deduction for expenses, fees, or taxes)		Russell Midcap® Value Index		18.51%	3.79%	10.63%	8.42%	Aug. 12, 1998

The Russell Midcap^® Value Index measures the performance of those Russell Midcap^® companies with lower price-to-book ratios and lower forecasted growth values. The stocks are also members of the Russell 1000^® Value Index. This index is used to calculate the performance fee adjustment.

After-tax returns are calculated using distributions for the Fund’s Class L Shares (formerly named Institutional Shares) for the periods following April 21, 2003; for Berger Mid Cap Value Fund – Institutional Shares for the period May 17, 2002 to April 17, 2003; and for Berger Mid Cap Value Fund – Investor Shares for periods prior to May 17, 2002. If Class L Shares of the Fund had been available during these earlier periods, distributions may have been different and thus, after-tax returns may have been different from those shown. After-tax returns are calculated using the historically highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes. Actual after-tax returns depend on your individual tax situation and may differ from those shown in the preceding table. The after-tax return information shown above does not apply to Fund shares held through a tax-deferred account, such as a 401(k) plan or an IRA.

[1] If the Fund incurs a loss, which generates a tax benefit, the Return After Taxes on Distributions and Sale of Fund Shares may exceed the Fund’s other return figures.

[1] Fund returns for periods prior to the Fund's adoption of share classes reflect a 0.25% 12b-1 fee, which has not been paid by the Class L Shares (formerly named Institutional Shares) since the class commenced investment operations on May 17, 2002.

XML

Label	Element	Value
Risk/Return:	rr_RiskReturnAbstract
Registrant Name	dei_EntityRegistrantName	JANUS INVESTMENT FUND
Prospectus Date	rr_ProspectusDate	Oct. 28, 2013
Perkins Small Cap Value Fund | Class A, C, S, I, N, R, T Shares
Risk/Return:	rr_RiskReturnAbstract
Risk/Return [Heading]	rr_RiskReturnHeading	FUND SUMMARY Perkins Small Cap Value Fund
Objective [Heading]	rr_ObjectiveHeading	INVESTMENT OBJECTIVE
Objective, Primary [Text Block]	rr_ObjectivePrimaryTextBlock	Perkins Small Cap Value Fund seeks capital appreciation.
Expense [Heading]	rr_ExpenseHeading	FEES AND EXPENSES OF THE FUND
Expense Narrative [Text Block]	rr_ExpenseNarrativeTextBlock	This table describes the fees and expenses that you may pay if you buy and hold Shares of the Fund. Each share class has different expenses, but represents an investment in the same Fund.
Shareholder Fees Caption [Text]	rr_ShareholderFeesCaption	SHAREHOLDER FEES (fees paid directly from your investment)
Operating Expenses Caption [Text]	rr_OperatingExpensesCaption	ANNUAL FUND OPERATING EXPENSES (expenses that you pay each year as a percentage of the value of your investment)
Portfolio Turnover [Heading]	rr_PortfolioTurnoverHeading	Portfolio Turnover:
Portfolio Turnover [Text Block]	rr_PortfolioTurnoverTextBlock	The Fund pays transaction costs, such as commissions, when it buys and sells securities (or “turns over” its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when Fund shares are held in a taxable account. These costs, which are not reflected in annual fund operating expenses or in the Example, affect the Fund’s performance. During the most recent fiscal year, the Fund’s portfolio turnover rate was 60% of the average value of its portfolio.
Portfolio Turnover, Rate	rr_PortfolioTurnoverRate	60.00%
Expense Breakpoint Discounts [Text]	rr_ExpenseBreakpointDiscounts	For Class A Shares, you may qualify for sales charge discounts if you and your family invest, or agree to invest in the future, at least $50,000 in the Fund or in other Janus mutual funds. More information about these and other discounts, as well as eligibility requirements for each share class, is available from your financial professional and in the “Purchases” section on page 66 of the Fund’s Prospectus and in the “Purchases” section on page 70 of the Fund’s Statement of Additional Information.
Expense Breakpoint, Minimum Investment Required [Amount]	rr_ExpenseBreakpointMinimumInvestmentRequiredAmount	$ 50,000
Expense Example [Heading]	rr_ExpenseExampleHeading	EXAMPLE:
Expense Example by Year [Heading]	rr_ExpenseExampleByYearHeading	The Example assumes that you invest $10,000 in the Fund for the time periods indicated and reinvest all dividends and distributions. The Example also assumes that your investment has a 5% return each year and that the Fund’s operating expenses remain the same. Although your actual costs may be higher or lower, based on these assumptions your costs would be:
Expense Example Narrative [Text Block]	rr_ExpenseExampleNarrativeTextBlock	The Example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds.
Expense Example by, Year, Caption [Text]	rr_ExpenseExampleByYearCaption	If Shares are redeemed:
Expense Example, No Redemption, By Year, Caption [Text]	rr_ExpenseExampleNoRedemptionByYearCaption	If Shares are not redeemed:
Strategy [Heading]	rr_StrategyHeading	PRINCIPAL INVESTMENT STRATEGIES
Strategy Narrative [Text Block]	rr_StrategyNarrativeTextBlock	The Fund pursues its investment objective by investing primarily in the common stocks of small companies whose stock prices are believed to be undervalued by the Fund’s portfolio managers. The Fund invests, under normal circumstances, at least 80% of its net assets in equity securities of small companies whose market capitalization, at the time of initial purchase, is less than the 12-month average of the maximum market capitalization for companies included in the Russell 2000® Value Index. This average is updated monthly. The market capitalizations within the index will vary, but as of June 30, 2013, they ranged from approximately $23 million to $5.6 billion. The Fund may also invest in foreign equity and debt securities, which may include investments in emerging markets. The Fund may invest, under normal circumstances, up to 20% of its net assets in securities of companies having market capitalizations outside of the aforementioned market capitalization ranges. In addition, when the portfolio managers believe that market conditions are unfavorable for investing, or when they are otherwise unable to locate attractive investment opportunities, the Fund may invest up to 20% of its net assets in cash or similar investments. The Fund’s securities selection focuses on companies that are out of favor with markets or have not yet been discovered by the broader investment community. The Fund’s portfolio managers generally look for companies with: strong balance sheets and solid recurring free cash flows attractive relative and absolute valuation ratios or that have underperformed recently favorable reward to risk characteristics The portfolio managers’ philosophy is to weigh a security’s downside risk before considering its upside potential, which may help provide an element of capital preservation.
Risk [Heading]	rr_RiskHeading	PRINCIPAL INVESTMENT RISKS
Risk Narrative [Text Block]	rr_RiskNarrativeTextBlock	The biggest risk is that the Fund’s returns will vary, and you could lose money. The Fund is designed for long-term investors seeking an equity portfolio, including common stocks. Common stocks tend to be more volatile than many other investment choices. Value Investing Risk. Because different types of stocks tend to shift in and out of favor depending on market and economic conditions, “value” stocks may perform differently than other types of stocks and from the market as a whole, and can continue to be undervalued by the market for long periods of time. It is also possible that a value stock will never appreciate to the extent expected by the portfolio managers. When the Fund’s investments in cash or similar investments increase due to a lack of favorable investment opportunities or other extraordinary factors, the Fund may not participate in market advances or declines to the same extent that it would if the Fund had been fully invested. Market Risk. The value of the Fund’s portfolio may decrease if the value of an individual company or security, or multiple companies or securities, in the portfolio decreases or if the portfolio managers’ belief about a company’s intrinsic worth is incorrect. Further, regardless of how well individual companies or securities perform, the value of the Fund’s portfolio could also decrease if there are deteriorating economic or market conditions. It is important to understand that the value of your investment may fall, sometimes sharply, in response to changes in the market, and you could lose money. Small-Sized Companies Risk. The Fund’s investments in securities issued by small-sized companies, which can include smaller, start-up companies offering emerging products or services, may involve greater risks than are customarily associated with larger, more established companies. Securities issued by small-sized companies tend to be more volatile and somewhat more speculative than securities issued by larger or more established companies and may underperform as compared to the securities of larger companies. Real Estate Securities Risk. The Fund’s performance may be affected by the risks associated with investments in real estate-related companies. The value of real estate-related companies’ securities is sensitive to changes in real estate values and rental income, property taxes, interest rates, tax and regulatory requirements, supply and demand, and the management skill and creditworthiness of the company. Investments in real estate investment trusts (“REITs”) involve the same risks as other real estate investments. In addition, a REIT could fail to qualify for tax-free pass-through of its income under the Internal Revenue Code or fail to maintain its exemption from registration under the Investment Company Act of 1940, as amended, which could produce adverse economic consequences for the REIT and its investors, including the Fund. An investment in the Fund is not a bank deposit and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency.
Risk Lose Money [Text]	rr_RiskLoseMoney	The biggest risk is that the Fund's returns will vary, and you could lose money.
Risk Not Insured Depository Institution [Text]	rr_RiskNotInsuredDepositoryInstitution	An investment in the Fund is not a bank deposit and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency.
Bar Chart and Performance Table [Heading]	rr_BarChartAndPerformanceTableHeading	PERFORMANCE INFORMATION
Performance Narrative [Text Block]	rr_PerformanceNarrativeTextBlock	The following information provides some indication of the risks of investing in the Fund by showing how the Fund’s performance has varied over time. Class T Shares (formerly named Class J Shares) of the Fund commenced operations with the Fund’s inception. Class A Shares, Class C Shares, Class S Shares, Class I Shares, and Class R Shares of the Fund commenced operations on July 6, 2009. Class N Shares of the Fund commenced operations on May 31, 2012. The performance shown for Class T Shares for periods following April 21, 2003, reflects the fees and expenses of Class T Shares in effect during the periods shown, net of any applicable fee and expense limitations or waivers. For the periods prior to April 21, 2003, the performance shown for Class T Shares reflects the historical performance of Berger Small Cap Value Fund – Investor Shares (as a result of a prior reorganization of Berger Small Cap Value Fund – Investor Shares into the Fund’s former Class J Shares). The performance shown for Class A Shares, Class C Shares, Class S Shares, and Class R Shares reflects the performance of the Fund’s Class J Shares (formerly named Investor Shares) from April 21, 2003 to July 6, 2009, calculated using the fees and expenses of each respective share class, without the effect of any fee and expense limitations or waivers. For periods prior to April 21, 2003, the performance shown for Class A Shares, Class C Shares, Class S Shares, and Class R Shares reflects the historical performance of Berger Small Cap Value Fund – Investor Shares (as a result of a prior reorganization of Berger Small Cap Value Fund – Investor Shares into the Fund’s former Class J Shares), calculated using the fees and expenses of each respective share class, without the effect of any fee and expense limitations or waivers. The performance shown for Class I Shares reflects the performance of the Fund’s Class J Shares (formerly named Investor Shares) from April 21, 2003 to July 6, 2009, calculated using the fees and expenses of Class J Shares, net of any applicable fee and expense limitations or waivers. For the periods prior to April 21, 2003, the performance shown for Class I Shares reflects the historical performance of Berger Small Cap Value Fund – Investor Shares (as a result of a prior reorganization of Berger Small Cap Value Fund – Investor Shares into the Fund’s former Class J Shares), calculated using the fees and expenses of Class J Shares, net of any applicable fee and expense limitations or waivers. The performance shown for Class N Shares reflects the performance of the Fund’s Class T Shares from July 6, 2009 to May 31, 2012, calculated using the fees and expenses of Class T Shares, net of any applicable fee and expense limitations or waivers. For the period from April 21, 2003 to July 6, 2009, the performance shown for Class N Shares reflects the performance of the Fund’s Class J Shares (formerly named Investor Shares), calculated using the fees and expenses of Class J Shares, net of any applicable fee and expense limitations or waivers. For the periods prior to April 21, 2003, the performance shown for Class N Shares reflects the historical performance of Berger Small Cap Value Fund – Investor Shares (as a result of a prior reorganization of Berger Small Cap Value Fund – Investor Shares into the Fund’s former Class J Shares), calculated using the fees and expenses of Class J Shares, net of any applicable fee and expense limitations or waivers. If Class A Shares, Class C Shares, Class S Shares, Class I Shares, and Class R Shares of the Fund had been available during periods prior to July 6, 2009, or Class N Shares of the Fund had been available during periods prior to May 31, 2012, the performance shown for each respective share class may have been different. The performance shown for periods following the Fund’s commencement of Class A Shares, Class C Shares, Class S Shares, Class I Shares, Class N Shares, and Class R Shares reflects the fees and expenses of each respective share class, net of any applicable fee and expense limitations or waivers. The bar chart depicts the change in performance from year to year during the periods indicated. The bar chart figures do not include any applicable sales charges that an investor may pay when they buy or sell Class A Shares or Class C Shares of the Fund. If sales charges were included, the returns would be lower. The table compares the Fund’s average annual returns for the periods indicated to a broad-based securities market index. The index is not actively managed and is not available for direct investment. All figures assume reinvestment of dividends and distributions. For certain periods, the Fund’s performance reflects the effect of expense waivers. Without the effect of these expense waivers, the performance shown would have been lower. The Fund’s past performance (before and after taxes) does not necessarily indicate how it will perform in the future. Updated performance information is available at janus.com/advisor/mutual-funds or by calling 1-877-335-2687.
Performance Information Illustrates Variability of Returns [Text]	rr_PerformanceInformationIllustratesVariabilityOfReturns	The following information provides some indication of the risks of investing in the Fund by showing how the Fund’s performance has varied over time. The bar chart depicts the change in performance from year to year during the periods indicated.
Performance Additional Market Index [Text]	rr_PerformanceAdditionalMarketIndex	The table compares the Fund’s average annual returns for the periods indicated to a broad-based securities market index. The index is not actively managed and is not available for direct investment. All figures assume reinvestment of dividends and distributions.
Performance Availability Phone [Text]	rr_PerformanceAvailabilityPhone	1-877-335-2687
Performance Availability Website Address [Text]	rr_PerformanceAvailabilityWebSiteAddress	janus.com/advisor/mutual-funds
Performance Past Does Not Indicate Future [Text]	rr_PerformancePastDoesNotIndicateFuture	The Fund’s past performance (before and after taxes) does not necessarily indicate how it will perform in the future.
Bar Chart [Heading]	rr_BarChartHeading	Annual Total Returns for Class T Shares (calendar year-end)
Bar Chart Does Not Reflect Sales Loads [Text]	rr_BarChartDoesNotReflectSalesLoads	The bar chart figures do not include any applicable sales charges that an investor may pay when they buy or sell Class A Shares or Class C Shares of the Fund. If sales charges were included, the returns would be lower.
Bar Chart Closing [Text Block]	rr_BarChartClosingTextBlock	Best Quarter:  Second Quarter 2009  23.04%          Worst Quarter:  Fourth Quarter 2008  −18.83%
Year to Date Return, Label	rr_YearToDateReturnLabel	The Fund’s year-to-date return as of the calendar quarter ended September 30, 2013 was 18.46%.
Performance Table Heading	rr_PerformanceTableHeading	Average Annual Total Returns (periods ended 12/31/12)
Performance Table Uses Highest Federal Rate	rr_PerformanceTableUsesHighestFederalRate	After-tax returns are calculated using the historically highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes.
Performance Table Not Relevant to Tax Deferred	rr_PerformanceTableNotRelevantToTaxDeferred	Actual after-tax returns depend on your individual tax situation and may differ from those shown in the preceding table. The after-tax return information shown above does not apply to Fund shares held through a tax-deferred account, such as a 401(k) plan or an IRA.
Performance Table One Class of after Tax Shown [Text]	rr_PerformanceTableOneClassOfAfterTaxShown	After-tax returns are only shown for Class T Shares of the Fund. After-tax returns for the other classes of Shares will vary from those shown for Class T Shares due to varying sales charges (as applicable), fees, and expenses among the classes.
Performance Table Explanation after Tax Higher	rr_PerformanceTableExplanationAfterTaxHigher	If the Fund incurs a loss, which generates a tax benefit, the Return After Taxes on Distributions and Sale of Fund Shares may exceed the Fund’s other return figures.
Performance Table Narrative	rr_PerformanceTableNarrativeTextBlock	The Russell 2000® Value Index measures the performance of those Russell 2000® companies with lower price-to-book ratios and lower forecasted growth values. This index is used to calculate the performance fee adjustment. After-tax returns are calculated using distributions for the Fund’s Class T Shares (formerly named Class J Shares) for the periods following April 21, 2003; and for Berger Small Cap Value Fund – Investor Shares for periods prior to April 21, 2003. If Class T Shares of the Fund had been available during the periods prior to April 21, 2003, distributions may have been different and thus, after-tax returns may have been different from those shown. After-tax returns are calculated using the historically highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes. Actual after-tax returns depend on your individual tax situation and may differ from those shown in the preceding table. The after-tax return information shown above does not apply to Fund shares held through a tax-deferred account, such as a 401(k) plan or an IRA. After-tax returns are only shown for Class T Shares of the Fund. After-tax returns for the other classes of Shares will vary from those shown for Class T Shares due to varying sales charges (as applicable), fees, and expenses among the classes.
Performance Table Closing [Text Block]	rr_PerformanceTableClosingTextBlock	Updated performance information is available at janus.com/advisor/mutual-funds or by calling 1-877-335-2687.
Perkins Small Cap Value Fund | Class A, C, S, I, N, R, T Shares | Class A
Risk/Return:	rr_RiskReturnAbstract
Shareholder Fees Column [Text]	rr_ShareholderFeesColumnName	Class A
Maximum Sales Charge (load) Imposed on Purchases (as a percentage of offering price)	rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice	5.75%
Maximum Deferred Sales Charge (load) (as a percentage of the lower of original purchase price or redemption proceeds)	rr_MaximumDeferredSalesChargeOverOther	none
Operating Expenses Column [Text]	rr_OperatingExpensesColumnName	Class A
Management Fees (may adjust up or down)	rr_ManagementFeesOverAssets	0.56%
Distribution/Service (12b-1) Fees	rr_DistributionAndService12b1FeesOverAssets	0.25%
Other Expenses	rr_OtherExpensesOverAssets	0.19%
Total Annual Fund Operating Expenses	rr_ExpensesOverAssets	1.00%
Expense Example, By Year, Column [Text]	rr_ExpenseExampleByYearColumnName	Class A Shares
1 Year	rr_ExpenseExampleYear01	671
3 Years	rr_ExpenseExampleYear03	875
5 Years	rr_ExpenseExampleYear05	1,096
10 Years	rr_ExpenseExampleYear10	1,729
Expense Example, No Redemption, By Year, Column [Text]	rr_ExpenseExampleNoRedemptionByYearColumnName	Class A Shares
1 Year	rr_ExpenseExampleNoRedemptionYear01	671
3 Years	rr_ExpenseExampleNoRedemptionYear03	875
5 Years	rr_ExpenseExampleNoRedemptionYear05	1,096
10 Years	rr_ExpenseExampleNoRedemptionYear10	1,729
Perkins Small Cap Value Fund | Class A, C, S, I, N, R, T Shares | Class C
Risk/Return:	rr_RiskReturnAbstract
Shareholder Fees Column [Text]	rr_ShareholderFeesColumnName	Class C
Maximum Sales Charge (load) Imposed on Purchases (as a percentage of offering price)	rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice	none
Maximum Deferred Sales Charge (load) (as a percentage of the lower of original purchase price or redemption proceeds)	rr_MaximumDeferredSalesChargeOverOther	1.00%
Operating Expenses Column [Text]	rr_OperatingExpensesColumnName	Class C
Management Fees (may adjust up or down)	rr_ManagementFeesOverAssets	0.56%
Distribution/Service (12b-1) Fees	rr_DistributionAndService12b1FeesOverAssets	1.00%
Other Expenses	rr_OtherExpensesOverAssets	0.30%
Total Annual Fund Operating Expenses	rr_ExpensesOverAssets	1.86%
Expense Example, By Year, Column [Text]	rr_ExpenseExampleByYearColumnName	Class C Shares
1 Year	rr_ExpenseExampleYear01	289
3 Years	rr_ExpenseExampleYear03	585
5 Years	rr_ExpenseExampleYear05	1,006
10 Years	rr_ExpenseExampleYear10	2,180
Expense Example, No Redemption, By Year, Column [Text]	rr_ExpenseExampleNoRedemptionByYearColumnName	Class C Shares
1 Year	rr_ExpenseExampleNoRedemptionYear01	189
3 Years	rr_ExpenseExampleNoRedemptionYear03	585
5 Years	rr_ExpenseExampleNoRedemptionYear05	1,006
10 Years	rr_ExpenseExampleNoRedemptionYear10	2,180
Perkins Small Cap Value Fund | Class A, C, S, I, N, R, T Shares | Class S
Risk/Return:	rr_RiskReturnAbstract
Shareholder Fees Column [Text]	rr_ShareholderFeesColumnName	Class S
Maximum Sales Charge (load) Imposed on Purchases (as a percentage of offering price)	rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice	none
Maximum Deferred Sales Charge (load) (as a percentage of the lower of original purchase price or redemption proceeds)	rr_MaximumDeferredSalesChargeOverOther	none
Operating Expenses Column [Text]	rr_OperatingExpensesColumnName	Class S
Management Fees (may adjust up or down)	rr_ManagementFeesOverAssets	0.56%
Distribution/Service (12b-1) Fees	rr_DistributionAndService12b1FeesOverAssets	0.25%
Other Expenses	rr_OtherExpensesOverAssets	0.29%
Total Annual Fund Operating Expenses	rr_ExpensesOverAssets	1.10%
Expense Example, By Year, Column [Text]	rr_ExpenseExampleByYearColumnName	Class S Shares
1 Year	rr_ExpenseExampleYear01	112
3 Years	rr_ExpenseExampleYear03	350
5 Years	rr_ExpenseExampleYear05	606
10 Years	rr_ExpenseExampleYear10	1,340
Expense Example, No Redemption, By Year, Column [Text]	rr_ExpenseExampleNoRedemptionByYearColumnName	Class S Shares
1 Year	rr_ExpenseExampleNoRedemptionYear01	112
3 Years	rr_ExpenseExampleNoRedemptionYear03	350
5 Years	rr_ExpenseExampleNoRedemptionYear05	606
10 Years	rr_ExpenseExampleNoRedemptionYear10	1,340
Perkins Small Cap Value Fund | Class A, C, S, I, N, R, T Shares | Class I
Risk/Return:	rr_RiskReturnAbstract
Shareholder Fees Column [Text]	rr_ShareholderFeesColumnName	Class I
Maximum Sales Charge (load) Imposed on Purchases (as a percentage of offering price)	rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice	none
Maximum Deferred Sales Charge (load) (as a percentage of the lower of original purchase price or redemption proceeds)	rr_MaximumDeferredSalesChargeOverOther	none
Operating Expenses Column [Text]	rr_OperatingExpensesColumnName	Class I
Management Fees (may adjust up or down)	rr_ManagementFeesOverAssets	0.56%
Distribution/Service (12b-1) Fees	rr_DistributionAndService12b1FeesOverAssets	none
Other Expenses	rr_OtherExpensesOverAssets	0.15%
Total Annual Fund Operating Expenses	rr_ExpensesOverAssets	0.71%
Expense Example, By Year, Column [Text]	rr_ExpenseExampleByYearColumnName	Class I Shares
1 Year	rr_ExpenseExampleYear01	73
3 Years	rr_ExpenseExampleYear03	227
5 Years	rr_ExpenseExampleYear05	395
10 Years	rr_ExpenseExampleYear10	883
Expense Example, No Redemption, By Year, Column [Text]	rr_ExpenseExampleNoRedemptionByYearColumnName	Class I Shares
1 Year	rr_ExpenseExampleNoRedemptionYear01	73
3 Years	rr_ExpenseExampleNoRedemptionYear03	227
5 Years	rr_ExpenseExampleNoRedemptionYear05	395
10 Years	rr_ExpenseExampleNoRedemptionYear10	883
Perkins Small Cap Value Fund | Class A, C, S, I, N, R, T Shares | Class N
Risk/Return:	rr_RiskReturnAbstract
Shareholder Fees Column [Text]	rr_ShareholderFeesColumnName	Class N
Maximum Sales Charge (load) Imposed on Purchases (as a percentage of offering price)	rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice	none
Maximum Deferred Sales Charge (load) (as a percentage of the lower of original purchase price or redemption proceeds)	rr_MaximumDeferredSalesChargeOverOther	none
Operating Expenses Column [Text]	rr_OperatingExpensesColumnName	Class N
Management Fees (may adjust up or down)	rr_ManagementFeesOverAssets	0.56%
Distribution/Service (12b-1) Fees	rr_DistributionAndService12b1FeesOverAssets	none
Other Expenses	rr_OtherExpensesOverAssets	0.04%
Total Annual Fund Operating Expenses	rr_ExpensesOverAssets	0.60%
Expense Example, By Year, Column [Text]	rr_ExpenseExampleByYearColumnName	Class N Shares
1 Year	rr_ExpenseExampleYear01	61
3 Years	rr_ExpenseExampleYear03	192
5 Years	rr_ExpenseExampleYear05	335
10 Years	rr_ExpenseExampleYear10	750
Expense Example, No Redemption, By Year, Column [Text]	rr_ExpenseExampleNoRedemptionByYearColumnName	Class N Shares
1 Year	rr_ExpenseExampleNoRedemptionYear01	61
3 Years	rr_ExpenseExampleNoRedemptionYear03	192
5 Years	rr_ExpenseExampleNoRedemptionYear05	335
10 Years	rr_ExpenseExampleNoRedemptionYear10	750
Perkins Small Cap Value Fund | Class A, C, S, I, N, R, T Shares | Class R
Risk/Return:	rr_RiskReturnAbstract
Shareholder Fees Column [Text]	rr_ShareholderFeesColumnName	Class R
Maximum Sales Charge (load) Imposed on Purchases (as a percentage of offering price)	rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice	none
Maximum Deferred Sales Charge (load) (as a percentage of the lower of original purchase price or redemption proceeds)	rr_MaximumDeferredSalesChargeOverOther	none
Operating Expenses Column [Text]	rr_OperatingExpensesColumnName	Class R
Management Fees (may adjust up or down)	rr_ManagementFeesOverAssets	0.56%
Distribution/Service (12b-1) Fees	rr_DistributionAndService12b1FeesOverAssets	0.50%
Other Expenses	rr_OtherExpensesOverAssets	0.29%
Total Annual Fund Operating Expenses	rr_ExpensesOverAssets	1.35%
Expense Example, By Year, Column [Text]	rr_ExpenseExampleByYearColumnName	Class R Shares
1 Year	rr_ExpenseExampleYear01	137
3 Years	rr_ExpenseExampleYear03	428
5 Years	rr_ExpenseExampleYear05	739
10 Years	rr_ExpenseExampleYear10	1,624
Expense Example, No Redemption, By Year, Column [Text]	rr_ExpenseExampleNoRedemptionByYearColumnName	Class R Shares
1 Year	rr_ExpenseExampleNoRedemptionYear01	137
3 Years	rr_ExpenseExampleNoRedemptionYear03	428
5 Years	rr_ExpenseExampleNoRedemptionYear05	739
10 Years	rr_ExpenseExampleNoRedemptionYear10	1,624
Perkins Small Cap Value Fund | Class A, C, S, I, N, R, T Shares | Class T
Risk/Return:	rr_RiskReturnAbstract
Shareholder Fees Column [Text]	rr_ShareholderFeesColumnName	Class T
Maximum Sales Charge (load) Imposed on Purchases (as a percentage of offering price)	rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice	none
Maximum Deferred Sales Charge (load) (as a percentage of the lower of original purchase price or redemption proceeds)	rr_MaximumDeferredSalesChargeOverOther	none
Operating Expenses Column [Text]	rr_OperatingExpensesColumnName	Class T
Management Fees (may adjust up or down)	rr_ManagementFeesOverAssets	0.56%
Distribution/Service (12b-1) Fees	rr_DistributionAndService12b1FeesOverAssets	none
Other Expenses	rr_OtherExpensesOverAssets	0.29%
Total Annual Fund Operating Expenses	rr_ExpensesOverAssets	0.85%
Expense Example, By Year, Column [Text]	rr_ExpenseExampleByYearColumnName	Class T Shares
1 Year	rr_ExpenseExampleYear01	87
3 Years	rr_ExpenseExampleYear03	271
5 Years	rr_ExpenseExampleYear05	471
10 Years	rr_ExpenseExampleYear10	1,049
Expense Example, No Redemption, By Year, Column [Text]	rr_ExpenseExampleNoRedemptionByYearColumnName	Class T Shares
1 Year	rr_ExpenseExampleNoRedemptionYear01	87
3 Years	rr_ExpenseExampleNoRedemptionYear03	271
5 Years	rr_ExpenseExampleNoRedemptionYear05	471
10 Years	rr_ExpenseExampleNoRedemptionYear10	$ 1,049
2003	rr_AnnualReturn2003	36.78%
2004	rr_AnnualReturn2004	13.57%
2005	rr_AnnualReturn2005	8.90%
2006	rr_AnnualReturn2006	12.37%
2007	rr_AnnualReturn2007	2.97%
2008	rr_AnnualReturn2008	(21.79%)
2009	rr_AnnualReturn2009	36.59%
2010	rr_AnnualReturn2010	17.87%
2011	rr_AnnualReturn2011	(3.43%)
2012	rr_AnnualReturn2012	8.99%
Bar Chart, Year to Date Return, Date	rr_BarChartYearToDateReturnDate	Sep. 30, 2013
Bar Chart, Year to Date Return	rr_BarChartYearToDateReturn	18.46%
Highest Quarterly Return, Label	rr_HighestQuarterlyReturnLabel	Best Quarter:
Highest Quarterly Return, Date	rr_BarChartHighestQuarterlyReturnDate	Jun. 30, 2009
Highest Quarterly Return	rr_BarChartHighestQuarterlyReturn	23.04%
Lowest Quarterly Return, Label	rr_LowestQuarterlyReturnLabel	Worst Quarter:
Lowest Quarterly Return, Date	rr_BarChartLowestQuarterlyReturnDate	Dec. 31, 2008
Lowest Quarterly Return	rr_BarChartLowestQuarterlyReturn	(18.83%)
Perkins Small Cap Value Fund | Class A, C, S, I, N, R, T Shares | Return Before Taxes | Class A
Risk/Return:	rr_RiskReturnAbstract
Column	rr_AverageAnnualReturnColumnName	Class A Shares
Label	rr_AverageAnnualReturnLabel	Return Before Taxes	[1]
1 Year	rr_AverageAnnualReturnYear01	2.52%
5 Years	rr_AverageAnnualReturnYear05	4.36%
10 Years	rr_AverageAnnualReturnYear10	9.09%
Perkins Small Cap Value Fund | Class A, C, S, I, N, R, T Shares | Return Before Taxes | Class C
Risk/Return:	rr_RiskReturnAbstract
Column	rr_AverageAnnualReturnColumnName	Class C Shares
Label	rr_AverageAnnualReturnLabel	Return Before Taxes	[2]
1 Year	rr_AverageAnnualReturnYear01	6.95%
5 Years	rr_AverageAnnualReturnYear05	4.77%
10 Years	rr_AverageAnnualReturnYear10	8.96%
Perkins Small Cap Value Fund | Class A, C, S, I, N, R, T Shares | Return Before Taxes | Class S
Risk/Return:	rr_RiskReturnAbstract
Column	rr_AverageAnnualReturnColumnName	Class S Shares
Label	rr_AverageAnnualReturnLabel	Return Before Taxes
1 Year	rr_AverageAnnualReturnYear01	8.76%
5 Years	rr_AverageAnnualReturnYear05	5.55%
10 Years	rr_AverageAnnualReturnYear10	9.74%
Perkins Small Cap Value Fund | Class A, C, S, I, N, R, T Shares | Return Before Taxes | Class I
Risk/Return:	rr_RiskReturnAbstract
Column	rr_AverageAnnualReturnColumnName	Class I Shares
Label	rr_AverageAnnualReturnLabel	Return Before Taxes
1 Year	rr_AverageAnnualReturnYear01	9.13%
5 Years	rr_AverageAnnualReturnYear05	5.80%
10 Years	rr_AverageAnnualReturnYear10	10.00%
Perkins Small Cap Value Fund | Class A, C, S, I, N, R, T Shares | Return Before Taxes | Class N
Risk/Return:	rr_RiskReturnAbstract
Column	rr_AverageAnnualReturnColumnName	Class N Shares
Label	rr_AverageAnnualReturnLabel	Return Before Taxes
1 Year	rr_AverageAnnualReturnYear01	8.99%
5 Years	rr_AverageAnnualReturnYear05	5.80%
10 Years	rr_AverageAnnualReturnYear10	10.00%
Perkins Small Cap Value Fund | Class A, C, S, I, N, R, T Shares | Return Before Taxes | Class R
Risk/Return:	rr_RiskReturnAbstract
Column	rr_AverageAnnualReturnColumnName	Class R Shares
Label	rr_AverageAnnualReturnLabel	Return Before Taxes
1 Year	rr_AverageAnnualReturnYear01	8.43%
5 Years	rr_AverageAnnualReturnYear05	5.27%
10 Years	rr_AverageAnnualReturnYear10	9.47%
Perkins Small Cap Value Fund | Class A, C, S, I, N, R, T Shares | Return Before Taxes | Class T
Risk/Return:	rr_RiskReturnAbstract
Column	rr_AverageAnnualReturnColumnName	Class T Shares
Label	rr_AverageAnnualReturnLabel	Return Before Taxes
1 Year	rr_AverageAnnualReturnYear01	8.99%
5 Years	rr_AverageAnnualReturnYear05	5.80%
10 Years	rr_AverageAnnualReturnYear10	10.00%
Perkins Small Cap Value Fund | Class A, C, S, I, N, R, T Shares | Return After Taxes on Distributions | Class T
Risk/Return:	rr_RiskReturnAbstract
Column	rr_AverageAnnualReturnColumnName	Class T Shares
Label	rr_AverageAnnualReturnLabel	Return After Taxes on Distributions
1 Year	rr_AverageAnnualReturnYear01	8.13%
5 Years	rr_AverageAnnualReturnYear05	4.59%
10 Years	rr_AverageAnnualReturnYear10	8.09%
Perkins Small Cap Value Fund | Class A, C, S, I, N, R, T Shares | Return After Taxes on Distributions and Sale of Fund Shares | Class T
Risk/Return:	rr_RiskReturnAbstract
Column	rr_AverageAnnualReturnColumnName	Class T Shares
Label	rr_AverageAnnualReturnLabel	Return After Taxes on Distributions and Sale of Fund Shares	[3]
1 Year	rr_AverageAnnualReturnYear01	7.01%
5 Years	rr_AverageAnnualReturnYear05	4.65%
10 Years	rr_AverageAnnualReturnYear10	8.23%
Perkins Small Cap Value Fund | Class A, C, S, I, N, R, T Shares | Russell 2000® Value Index (reflects no deduction for expenses, fees, or taxes)
Risk/Return:	rr_RiskReturnAbstract
Label	rr_AverageAnnualReturnLabel	Russell 2000® Value Index
1 Year	rr_AverageAnnualReturnYear01	18.05%
5 Years	rr_AverageAnnualReturnYear05	3.55%
10 Years	rr_AverageAnnualReturnYear10	9.50%

[1] Calculated assuming maximum permitted sales loads.

[2] The one year return is calculated to include the contingent deferred sales charge.

[3] If the Fund incurs a loss, which generates a tax benefit, the Return After Taxes on Distributions and Sale of Fund Shares may exceed the Fund’s other return figures.

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Janus Government Money Market Fund | Class T Shares

FUND SUMMARY

Janus Government Money Market Fund

INVESTMENT OBJECTIVES

Janus Government Money Market Fund seeks capital preservation and liquidity with current income as a secondary objective.

FEES AND EXPENSES OF THE FUND

This table describes the fees and expenses that you may pay if you buy and hold Shares of the Fund.

ANNUAL FUND OPERATING EXPENSES
(expenses that you pay each year as a percentage of the value of your investment)

Annual Fund Operating Expenses	Janus Government Money Market Fund Class T Shares Class T
Operating Expenses Column [Text]	Class T
Management Fees	0.20%
Other Expenses	0.53%
Total Annual Fund Operating Expenses	0.73%

EXAMPLE:

The Example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds.

The Example assumes that you invest $10,000 in the Fund for the time periods indicated, reinvest all dividends and distributions, and then redeem all of your Shares at the end of each period. The Example also assumes that your investment has a 5% return each year and that the Fund’s operating expenses remain the same. Although your actual costs may be higher or lower, based on these assumptions your costs would be:

Expense Example (USD $)	Expense Example, By Year, Column [Text]	1 Year	3 Years	5 Years	10 Years
Janus Government Money Market Fund Class T Shares Class T	Class T Shares	75	233	406	906

PRINCIPAL INVESTMENT STRATEGIES

The Fund pursues its investment objectives by investing exclusively in obligations issued and/or guaranteed as to principal and interest by the United States Government or by its agencies and instrumentalities, and repurchase agreements secured by such obligations. Although U.S. Government agencies and instrumentalities may be chartered or sponsored by Acts of Congress, their securities are not issued by, and may not be guaranteed by (i.e., backed by the full faith and credit of), the United States Treasury. Some government agency and instrumentality securities not backed by the full faith and credit of the United States are supported by the issuer’s ability to borrow from the U.S. Treasury, some are supported only by the credit of the issuer, and some are supported by the United States in some other way. For securities not backed by the full faith and credit of the U.S. Treasury, the Fund must look principally to the agency or instrumentality issuing or guaranteeing the securities for repayment and may not be able to assert a claim against the United States if the agency or instrumentality does not meet its commitment. The Fund’s investments in securities issued by U.S. Government agencies and instrumentalities may be significant.

The Fund will:

• invest in high quality, short-term money market instruments that present minimal credit risks, as determined by Janus Capital

• invest only in U.S. dollar-denominated instruments that have a remaining maturity of 397 days or less (as calculated pursuant to Rule 2a-7 under the Investment Company Act of 1940, as amended)

• maintain a dollar-weighted average portfolio maturity of 60 days or less and maintain a dollar-weighted average portfolio life (portfolio maturity measured without reference to any maturity shortening provisions of adjustable rate securities by reference to their interest rate reset dates) of 120 days or less

PRINCIPAL INVESTMENT RISKS

Market Risk. The Fund’s yield will vary as the short-term securities in its portfolio mature and the proceeds are reinvested in securities with different interest rates. For capital preservation and liquidity, the Fund may have a greater concentration in short-term securities including, but not limited to, investing up to all of its assets in overnight securities, which may result in a reduction of the Fund’s yield. Over time, the real value of the Fund’s yield may be eroded by inflation. Although the Fund invests only in high-quality, short-term money market instruments, there is a risk that the value of the securities it holds will fall as a result of changes in interest rates, an issuer’s actual or perceived creditworthiness, or an issuer’s ability to meet its obligations. The credit quality of the Fund’s holdings can change rapidly in certain market environments and any downgrade or default of a portfolio security could cause the Fund’s share price or yield to fall.

Collateral Risk. With respect to collateral received in repurchase transactions or other investments, the Fund may have significant exposure to government agencies not secured by the full faith and credit of the United States. Such exposure, depending on market conditions, could have a negative impact on the Fund, including minimizing the value of any collateral.

Money Market Risk. An investment in the Fund is not a bank deposit and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency. Although the Fund seeks to preserve the value of your investment at $1.00 per share, it is possible to lose money by investing in the Fund.

PERFORMANCE INFORMATION

The following information provides some indication of the risks of investing in the Fund by showing how the Fund’s performance has varied over time. Class T Shares (formerly named Class J Shares, the initial share class) of the Fund commenced operations with the Fund’s inception. The performance shown for Class T Shares is calculated using the fees and expenses of Class T Shares in effect during the periods shown, net of any applicable fee and expense limitations or waivers.

The bar chart depicts the change in performance from year to year during the periods indicated. The table shows how the Fund’s returns over different periods average out. All figures assume reinvestment of dividends and distributions. For certain periods, the Fund’s performance reflects the effect of expense waivers. Without the effect of these expense waivers, the performance shown would have been lower.

The Fund’s past performance does not necessarily indicate how it will perform in the future. Updated performance information is available at janus.com/advisor/mutual-funds or by calling 1-877-335-2687.

Annual Total Returns for Class T Shares (calendar year-end)

Best Quarter:  Fourth Quarter 2006  1.21%          Worst Quarter:  Third Quarter 2011  0.00%

The Fund’s year-to-date return as of the calendar quarter ended September 30, 2013 was 0.00%.

Average Annual Total Returns (periods ended 12/31/12)

Average Annual Total Returns	Column	Label	1 Year	5 Years	10 Years	Since Inception	Inception Date
Janus Government Money Market Fund Class T Shares Class T Return Before Taxes	Class T Shares	Return Before Taxes	none	0.37%	1.51%	2.82%	Feb. 14, 1995

The 7-day yield on December 31, 2012 was 0.01% for Janus Government Money Market Fund.

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INTECH U.S. Core Fund | Class D Shares

FUND SUMMARY

INTECH U.S. Core Fund

INVESTMENT OBJECTIVE

INTECH U.S. Core Fund seeks long-term growth of capital.

FEES AND EXPENSES OF THE FUND

This table describes the fees and expenses that you may pay if you buy and hold Shares of the Fund.

ANNUAL FUND OPERATING EXPENSES
(expenses that you pay each year as a percentage of the value of your investment)

Annual Fund Operating Expenses	INTECH U.S. Core Fund Class D Shares Class D
Operating Expenses Column [Text]	Class D
Management Fees (may adjust up or down)	0.60%
Other Expenses	0.25%
Total Annual Fund Operating Expenses	0.85%

EXAMPLE:

The Example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds.

The Example assumes that you invest $10,000 in the Fund for the time periods indicated, reinvest all dividends and distributions, and then redeem all of your Shares at the end of each period. The Example also assumes that your investment has a 5% return each year and that the Fund’s operating expenses remain the same. Although your actual costs may be higher or lower, based on these assumptions your costs would be:

Expense Example (USD $)	Expense Example, By Year, Column [Text]	1 Year	3 Years	5 Years	10 Years
INTECH U.S. Core Fund Class D Shares	Class D Shares	87	271	471	1,049

Portfolio Turnover:

The Fund pays transaction costs, such as commissions, when it buys and sells securities (or “turns over” its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when Fund shares are held in a taxable account. These costs, which are not reflected in annual fund operating expenses or in the Example, affect the Fund’s performance. During the most recent fiscal year, the Fund’s portfolio turnover rate was 67% of the average value of its portfolio.

PRINCIPAL INVESTMENT STRATEGIES

The Fund invests, under normal circumstances, at least 80% of its net assets in U.S. common stocks from the universe of the S&P 500^® Index, utilizing INTECH’s mathematical investment process. The S&P 500^® Index is an unmanaged index of 500 stocks that is generally representative of the performance of larger companies in the United States.

The Fund pursues its investment objective by applying a mathematical investment process to construct an investment portfolio from the universe of common stocks within its named benchmark index. The goal of this process is to build a portfolio of stocks in a more efficient combination than the named benchmark index. The process seeks to capitalize on the natural volatility of the market by searching for stocks within the index that have high relative volatility (providing the potential for excess returns) but that essentially move in opposite directions or have low correlation to each other (providing the potential for lower relative risk). By constructing the portfolio in this manner and periodically rebalancing the portfolio to maintain potentially more efficient weightings, INTECH’s mathematical investment process seeks to create a portfolio that, over time, produces returns in excess of its named benchmark index with risks similar to that of the benchmark index. The rebalancing techniques used by INTECH may result in a higher portfolio turnover compared to a “buy and hold” fund strategy.

The Fund may lend portfolio securities on a short-term or long-term basis, in an amount equal to up to 1/3 of its total assets as determined at the time of the loan origination.

PRINCIPAL INVESTMENT RISKS

The biggest risk is that the Fund’s returns will vary, and you could lose money. The Fund is designed for long-term investors seeking an equity portfolio, including common stocks. Common stocks tend to be more volatile than many other investment choices.

Market Risk. The value of the Fund’s portfolio may decrease if the value of an individual company or security, or multiple companies or securities, in the portfolio decreases. Further, regardless of how well individual companies or securities perform, the value of the Fund’s portfolio could also decrease if there are deteriorating economic or market conditions. It is important to understand that the value of your investment may fall, sometimes sharply, in response to changes in the market, and you could lose money.

Investment Process Risk. The proprietary mathematical investment process used by INTECH may not achieve the desired results. There is a risk that INTECH’s method of identifying stocks with higher volatility than the named benchmark index or its method of identifying stocks that tend to move in the same or opposite direction relative to each other (correlation) will not result in selecting stocks with continuing volatility or the expected correlation. In INTECH’s history, which spans more than 25 years, INTECH’s mathematical investment process has experienced periods of both underperformance and outperformance relative to an identified benchmark. Even when the proprietary mathematical investment process is working appropriately, INTECH expects that there will be periods of underperformance relative to the benchmark. On an occasional basis, INTECH makes changes to its mathematical investment process. These changes may result in changes to the portfolio, might not provide the intended results, and may adversely impact the Fund’s performance.

Portfolio Turnover Risk. Increased portfolio turnover may result in higher costs, which may have a negative effect on the Fund’s performance. In addition, higher portfolio turnover may result in the acceleration of capital gains and the recognition of greater levels of short-term capital gains, which are taxed at ordinary federal income tax rates when distributed to shareholders.

Securities Lending Risk. The Fund may seek to earn additional income through lending its securities to certain qualified broker-dealers and institutions. There is the risk that when portfolio securities are lent, the securities may not be returned on a timely basis, and the Fund may experience delays and costs in recovering the security or gaining access to the collateral provided to the Fund to collateralize the loan. If the Fund is unable to recover a security on loan, the Fund may use the collateral to purchase replacement securities in the market. There is a risk that the value of the collateral could decrease below the cost of the replacement security by the time the replacement investment is made, resulting in a loss to the Fund.

An investment in the Fund is not a bank deposit and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency.

PERFORMANCE INFORMATION

The following information provides some indication of the risks of investing in the Fund by showing how the Fund’s performance has varied over time. Class D Shares of the Fund commenced operations on February 16, 2010, as a result of the restructuring of Class J Shares, the predecessor share class. The performance shown for Class D Shares for periods prior to February 16, 2010, reflects the performance of the Fund’s former Class J Shares, calculated using the fees and expenses in effect during the periods shown, net of any applicable fee and expense limitations or waivers. If Class D Shares of the Fund had been available during periods prior to February 16, 2010, the performance shown may have been different. The performance shown for periods following the Fund’s commencement of Class D Shares reflects the fees and expenses of Class D Shares, net of any applicable fee and expense limitations or waivers.

The bar chart depicts the change in performance from year to year during the periods indicated. The table compares the Fund’s average annual returns for the periods indicated to a broad-based securities market index. The index is not actively managed and is not available for direct investment. All figures assume reinvestment of dividends and distributions. For certain periods, the Fund’s performance reflects the effect of expense waivers. Without the effect of these expense waivers, the performance shown would have been lower.

The Fund’s past performance (before and after taxes) does not necessarily indicate how it will perform in the future. Updated performance information is available at janus.com/allfunds or by calling 1-800-525-3713.

Annual Total Returns for Class D Shares (calendar year-end)

Best Quarter:  Second Quarter 2009  14.79%          Worst Quarter:  Fourth Quarter 2008  −21.49%

The Fund’s year-to-date return as of the calendar quarter ended September 30, 2013 was 21.75%.

Average Annual Total Returns (periods ended 12/31/12)

Average Annual Total Returns INTECH U.S. Core Fund Class D Shares	Column	Label	1 Year	5 Years	Since Inception	Inception Date
Return Before Taxes	Class D Shares	Return Before Taxes	14.66%	1.80%	8.49%	Feb. 28, 2003
Return After Taxes on Distributions	Class D Shares	Return After Taxes on Distributions	14.42%	1.58%	7.81%	Feb. 28, 2003
Return After Taxes on Distributions and Sale of Fund Shares	Class D Shares	Return After Taxes on Distributions and Sale of Fund Shares	9.86%	1.49%	7.34%	Feb. 28, 2003
S&P 500® Index (reflects no deduction for expenses, fees, or taxes)		S&P 500® Index	16.00%	1.66%	7.68%	Feb. 28, 2003

The Standard & Poor’s (“S&P”) 500^® Index is a commonly recognized, market-capitalization weighted index of 500 widely held equity securities, designed to measure broad U.S. equity performance. This index is used to calculate the performance fee adjustment.

After-tax returns are calculated using distributions for the Fund’s Class D Shares for the periods following February 16, 2010; and for the Fund’s Class J Shares, the predecessor share class, for the periods prior to February 16, 2010. If Class D Shares of the Fund had been available during these earlier periods, distributions may have been different and thus, after-tax returns may have been different from those shown. After-tax returns are calculated using the historically highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes. Actual after-tax returns depend on your individual tax situation and may differ from those shown in the preceding table. The after-tax return information shown above does not apply to Fund shares held through a tax-deferred account, such as a 401(k) plan or an IRA.

XML

Label	Element	Value
Risk/Return:	rr_RiskReturnAbstract
Registrant Name	dei_EntityRegistrantName	JANUS INVESTMENT FUND
Prospectus Date	rr_ProspectusDate	Oct. 28, 2013
Janus Government Money Market Fund | Class D Shares
Risk/Return:	rr_RiskReturnAbstract
Risk/Return [Heading]	rr_RiskReturnHeading	FUND SUMMARY Janus Government Money Market Fund
Objective [Heading]	rr_ObjectiveHeading	INVESTMENT OBJECTIVES
Objective, Primary [Text Block]	rr_ObjectivePrimaryTextBlock	Janus Government Money Market Fund seeks capital preservation and liquidity with current income as a secondary objective.
Expense [Heading]	rr_ExpenseHeading	FEES AND EXPENSES OF THE FUND
Expense Narrative [Text Block]	rr_ExpenseNarrativeTextBlock	This table describes the fees and expenses that you may pay if you buy and hold Shares of the Fund.
Operating Expenses Caption [Text]	rr_OperatingExpensesCaption	ANNUAL FUND OPERATING EXPENSES (expenses that you pay each year as a percentage of the value of your investment)
Expense Example [Heading]	rr_ExpenseExampleHeading	EXAMPLE:
Expense Example by Year [Heading]	rr_ExpenseExampleByYearHeading	The Example assumes that you invest $10,000 in the Fund for the time periods indicated, reinvest all dividends and distributions, and then redeem all of your Shares at the end of each period. The Example also assumes that your investment has a 5% return each year and that the Fund’s operating expenses remain the same. Although your actual costs may be higher or lower, based on these assumptions your costs would be:
Expense Example Narrative [Text Block]	rr_ExpenseExampleNarrativeTextBlock	The Example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds.
Strategy [Heading]	rr_StrategyHeading	PRINCIPAL INVESTMENT STRATEGIES
Strategy Narrative [Text Block]	rr_StrategyNarrativeTextBlock	The Fund pursues its investment objectives by investing exclusively in obligations issued and/or guaranteed as to principal and interest by the United States Government or by its agencies and instrumentalities, and repurchase agreements secured by such obligations. Although U.S. Government agencies and instrumentalities may be chartered or sponsored by Acts of Congress, their securities are not issued by, and may not be guaranteed by (i.e., backed by the full faith and credit of), the United States Treasury. Some government agency and instrumentality securities not backed by the full faith and credit of the United States are supported by the issuer’s ability to borrow from the U.S. Treasury, some are supported only by the credit of the issuer, and some are supported by the United States in some other way. For securities not backed by the full faith and credit of the U.S. Treasury, the Fund must look principally to the agency or instrumentality issuing or guaranteeing the securities for repayment and may not be able to assert a claim against the United States if the agency or instrumentality does not meet its commitment. The Fund’s investments in securities issued by U.S. Government agencies and instrumentalities may be significant. The Fund will: invest in high quality, short-term money market instruments that present minimal credit risks, as determined by Janus Capital invest only in U.S. dollar-denominated instruments that have a remaining maturity of 397 days or less (as calculated pursuant to Rule 2a-7 under the Investment Company Act of 1940, as amended) maintain a dollar-weighted average portfolio maturity of 60 days or less and maintain a dollar-weighted average portfolio life (portfolio maturity measured without reference to any maturity shortening provisions of adjustable rate securities by reference to their interest rate reset dates) of 120 days or less
Risk [Heading]	rr_RiskHeading	PRINCIPAL INVESTMENT RISKS
Risk Narrative [Text Block]	rr_RiskNarrativeTextBlock	Market Risk. The Fund’s yield will vary as the short-term securities in its portfolio mature and the proceeds are reinvested in securities with different interest rates. For capital preservation and liquidity, the Fund may have a greater concentration in short-term securities including, but not limited to, investing up to all of its assets in overnight securities, which may result in a reduction of the Fund’s yield. Over time, the real value of the Fund’s yield may be eroded by inflation. Although the Fund invests only in high-quality, short-term money market instruments, there is a risk that the value of the securities it holds will fall as a result of changes in interest rates, an issuer’s actual or perceived creditworthiness, or an issuer’s ability to meet its obligations. The credit quality of the Fund’s holdings can change rapidly in certain market environments and any downgrade or default of a portfolio security could cause the Fund’s share price or yield to fall. Collateral Risk. With respect to collateral received in repurchase transactions or other investments, the Fund may have significant exposure to government agencies not secured by the full faith and credit of the United States. Such exposure, depending on market conditions, could have a negative impact on the Fund, including minimizing the value of any collateral. Money Market Risk. An investment in the Fund is not a bank deposit and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency. Although the Fund seeks to preserve the value of your investment at $1.00 per share, it is possible to lose money by investing in the Fund.
Risk Money Market Fund [Text]	rr_RiskMoneyMarketFund	Money Market Risk. An investment in the Fund is not a bank deposit and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency. Although the Fund seeks to preserve the value of your investment at $1.00 per share, it is possible to lose money by investing in the Fund.
Bar Chart and Performance Table [Heading]	rr_BarChartAndPerformanceTableHeading	PERFORMANCE INFORMATION
Performance Narrative [Text Block]	rr_PerformanceNarrativeTextBlock	The following information provides some indication of the risks of investing in the Fund by showing how the Fund’s performance has varied over time. Class D Shares of the Fund commenced operations on February 16, 2010, as a result of the restructuring of Class J Shares, the predecessor share class. The performance shown for Class D Shares for periods prior to February 16, 2010, reflects the performance of the Fund’s former Class J Shares, calculated using the fees and expenses in effect during the periods shown, net of any applicable fee and expense limitations or waivers. If Class D Shares of the Fund had been available during periods prior to February 16, 2010, the performance shown may have been different. The performance shown for periods following the Fund’s commencement of Class D Shares reflects the fees and expenses of Class D Shares, net of any applicable fee and expense limitations or waivers. The bar chart depicts the change in performance from year to year during the periods indicated. The table shows how the Fund’s returns over different periods average out. All figures assume reinvestment of dividends and distributions. For certain periods, the Fund’s performance reflects the effect of expense waivers. Without the effect of these expense waivers, the performance shown would have been lower. The Fund’s past performance does not necessarily indicate how it will perform in the future. Updated performance information is available at janus.com/allfunds or by calling 1-800-525-3713.
Performance Information Illustrates Variability of Returns [Text]	rr_PerformanceInformationIllustratesVariabilityOfReturns	The following information provides some indication of the risks of investing in the Fund by showing how the Fund’s performance has varied over time. The bar chart depicts the change in performance from year to year during the periods indicated.
Performance Availability Phone [Text]	rr_PerformanceAvailabilityPhone	1-800-525-3713
Performance Availability Website Address [Text]	rr_PerformanceAvailabilityWebSiteAddress	janus.com/allfunds
Performance Past Does Not Indicate Future [Text]	rr_PerformancePastDoesNotIndicateFuture	The Fund’s past performance does not necessarily indicate how it will perform in the future.
Bar Chart [Heading]	rr_BarChartHeading	Annual Total Returns for Class D Shares (calendar year-end)
Bar Chart Closing [Text Block]	rr_BarChartClosingTextBlock	Best Quarter:  Fourth Quarter 2006  1.21%          Worst Quarter:  Third Quarter 2011  0.00%
Year to Date Return, Label	rr_YearToDateReturnLabel	The Fund’s year-to-date return as of the calendar quarter ended September 30, 2013 was 0.00%.
Performance Table Heading	rr_PerformanceTableHeading	Average Annual Total Returns (periods ended 12/31/12)
Performance Table Closing [Text Block]	rr_PerformanceTableClosingTextBlock	Updated performance information is available at janus.com/allfunds or by calling 1-800-525-3713.
Money Market Seven Day Yield, Caption [Text]	rr_MoneyMarketSevenDayYieldCaption	The 7-day yield on December 31, 2012 was 0.01% for Janus Government Money Market Fund.
Money Market Seven Day Yield	rr_MoneyMarketSevenDayYield	0.01%
Janus Government Money Market Fund | Class D Shares | Class D
Risk/Return:	rr_RiskReturnAbstract
Operating Expenses Column [Text]	rr_OperatingExpensesColumnName	Class D
Management Fees	rr_ManagementFeesOverAssets	0.20%
Other Expenses	rr_OtherExpensesOverAssets	0.49%
Total Annual Fund Operating Expenses	rr_ExpensesOverAssets	0.69%
Expense Example, By Year, Column [Text]	rr_ExpenseExampleByYearColumnName	Class D Shares
1 Year	rr_ExpenseExampleYear01	$ 70
3 Years	rr_ExpenseExampleYear03	221
5 Years	rr_ExpenseExampleYear05	384
10 Years	rr_ExpenseExampleYear10	$ 859
2003	rr_AnnualReturn2003	0.65%
2004	rr_AnnualReturn2004	0.85%
2005	rr_AnnualReturn2005	2.70%
2006	rr_AnnualReturn2006	4.52%
2007	rr_AnnualReturn2007	4.66%
2008	rr_AnnualReturn2008	1.83%
2009	rr_AnnualReturn2009	0.01%
2010	rr_AnnualReturn2010	0.02%
2011	rr_AnnualReturn2011	0.00%
2012	rr_AnnualReturn2012	0.00%
Bar Chart, Year to Date Return, Date	rr_BarChartYearToDateReturnDate	Sep. 30, 2013
Bar Chart, Year to Date Return	rr_BarChartYearToDateReturn	0.00%
Highest Quarterly Return, Label	rr_HighestQuarterlyReturnLabel	Best Quarter:
Highest Quarterly Return, Date	rr_BarChartHighestQuarterlyReturnDate	Dec. 31, 2006
Highest Quarterly Return	rr_BarChartHighestQuarterlyReturn	1.21%
Lowest Quarterly Return, Label	rr_LowestQuarterlyReturnLabel	Worst Quarter:
Lowest Quarterly Return, Date	rr_BarChartLowestQuarterlyReturnDate	Sep. 30, 2011
Lowest Quarterly Return	rr_BarChartLowestQuarterlyReturn	0.00%
Janus Government Money Market Fund | Class D Shares | Return Before Taxes | Class D
Risk/Return:	rr_RiskReturnAbstract
Column	rr_AverageAnnualReturnColumnName	Class D Shares
Label	rr_AverageAnnualReturnLabel	Return Before Taxes
1 Year	rr_AverageAnnualReturnYear01	none
5 Years	rr_AverageAnnualReturnYear05	0.37%
10 Years	rr_AverageAnnualReturnYear10	1.51%
Since Inception	rr_AverageAnnualReturnSinceInception	2.82%
Inception Date	rr_AverageAnnualReturnInceptionDate	Feb. 14, 1995

XML

INTECH Global Dividend Fund | Class A, C, S, I, T Shares

FUND SUMMARY

INTECH Global Dividend Fund

INVESTMENT OBJECTIVE

INTECH Global Dividend Fund seeks long-term growth of capital and income.

FEES AND EXPENSES OF THE FUND

This table describes the fees and expenses that you may pay if you buy and hold Shares of the Fund. Each share class has different expenses, but represents an investment in the same Fund.

For Class A Shares, you may qualify for sales charge discounts if you and your family invest, or agree to invest in the future, at least $50,000 in the Fund or in other Janus mutual funds. More information about these and other discounts, as well as eligibility requirements for each share class, is available from your financial professional and in the “Purchases” section on page 51 of the Fund’s Prospectus and in the “Purchases” section on page 70 of the Fund’s Statement of Additional Information.

SHAREHOLDER FEES
(fees paid directly from your investment)

Shareholder Fees INTECH Global Dividend Fund Class A, C, S, I, T Shares	Class A	Class C	Class S	Class I	Class T
Shareholder Fees Column [Text]	Class A	Class C	Class S	Class I	Class T
Maximum Sales Charge (load) Imposed on Purchases (as a percentage of offering price)	5.75%	none	none	none	none
Maximum Deferred Sales Charge (load) (as a percentage of the lower of original purchase price or redemption proceeds)	none	1.00%	none	none	none

ANNUAL FUND OPERATING EXPENSES
(expenses that you pay each year as a percentage of the value of your investment)

Annual Fund Operating Expenses INTECH Global Dividend Fund Class A, C, S, I, T Shares		Class A	Class C	Class S	Class I	Class T
Operating Expenses Column [Text]		Class A	Class C	Class S	Class I	Class T
Management Fees		0.55%	0.55%	0.55%	0.55%	0.55%
Distribution/Service (12b-1) Fees		0.25%	1.00%	0.25%	none	none
Other Expenses		1.89%	1.95%	2.16%	1.90%	2.14%
Total Annual Fund Operating Expenses	[1]	2.69%	3.50%	2.96%	2.45%	2.69%
Fee Waiver	[1]	1.92%	2.00%	1.96%	1.93%	1.94%
Total Annual Fund Operating Expenses After Fee Waiver	[1]	0.77%	1.50%	1.00%	0.52%	0.75%

EXAMPLE:

The following Example is based on expenses without waivers. The Example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds.

The Example assumes that you invest $10,000 in the Fund for the time periods indicated and reinvest all dividends and distributions. The Example also assumes that your investment has a 5% return each year and that the Fund’s operating expenses without waivers or recoupments (if applicable) remain the same. Although your actual costs may be higher or lower, based on these assumptions your costs would be:

If Shares are redeemed:

Expense Example INTECH Global Dividend Fund Class A, C, S, I, T Shares (USD $)	Expense Example, By Year, Column [Text]	1 Year	3 Years	5 Years	10 Years
Class A	Class A Shares	831	1,362	1,918	3,423
Class C	Class C Shares	453	1,074	1,817	3,774
Class S	Class S Shares	299	915	1,557	3,280
Class I	Class I Shares	248	764	1,306	2,786
Class T	Class T Shares	272	835	1,425	3,022

If Shares are not redeemed:

Expense Example, No Redemption INTECH Global Dividend Fund Class A, C, S, I, T Shares (USD $)	Expense Example, No Redemption, By Year, Column [Text]	1 Year	3 Years	5 Years	10 Years
Class A	Class A Shares	831	1,362	1,918	3,423
Class C	Class C Shares	353	1,074	1,817	3,774
Class S	Class S Shares	299	915	1,557	3,280
Class I	Class I Shares	248	764	1,306	2,786
Class T	Class T Shares	272	835	1,425	3,022

Portfolio Turnover: 

The Fund pays transaction costs, such as commissions, when it buys and sells securities (or “turns over” its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when Fund shares are held in a taxable account. These costs, which are not reflected in annual fund operating expenses or in the Example, affect the Fund’s performance. During the most recent fiscal year, the Fund’s portfolio turnover rate was 116% of the average value of its portfolio.

PRINCIPAL INVESTMENT STRATEGIES

The Fund invests, under normal circumstances, at least 80% of its net assets in dividend-paying securities. The Fund invests primarily in common stocks from the universe of the Morgan Stanley Capital International (“MSCI”) World High Dividend Yield Index, utilizing INTECH’s mathematical investment process. The MSCI World High Dividend Yield Index is designed to reflect the performance of the high dividend yield securities contained within the broader MSCI World Index^SM. The Fund may also invest in foreign equity and debt securities.

The Fund pursues its investment objective by applying a mathematical investment process to construct an investment portfolio from the universe of common stocks within its named benchmark index. The goal of this process is to build a portfolio of stocks in a more efficient combination than the named benchmark index. The process seeks to capitalize on the natural volatility of the market by searching for stocks within the index that have high relative volatility (providing the potential for excess returns) but that essentially move in opposite directions or have low correlation to each other (providing the potential for lower relative risk). By constructing the portfolio in this manner and periodically rebalancing the portfolio to maintain potentially more efficient weightings, INTECH’s mathematical investment process seeks to create a portfolio that, over time, produces returns in excess of its named benchmark index with risks similar to that of the benchmark index. The rebalancing techniques used by INTECH may result in a higher portfolio turnover compared to a “buy and hold” fund strategy.

The Fund may lend portfolio securities on a short-term or long-term basis, in an amount equal to up to 1/3 of its total assets as determined at the time of the loan origination.

PRINCIPAL INVESTMENT RISKS

The biggest risk is that the Fund’s returns will vary, and you could lose money. The Fund is designed for long-term investors seeking an equity portfolio, including common stocks. Common stocks tend to be more volatile than many other investment choices.

Foreign Exposure Risk. The Fund normally has significant exposure to foreign markets as a result of its investments in foreign securities, which can be more volatile than the U.S. markets. As a result, its returns and net asset value may be affected to a large degree by fluctuations in currency exchange rates or political or economic conditions in a particular country. In some foreign markets, there may not be protection against failure by other parties to complete transactions. It may not be possible for the Fund to repatriate capital, dividends, interest, and other income from a particular country or governmental entity. In addition, a market swing in one or more countries or regions where the Fund has invested a significant amount of its assets may have a greater effect on the Fund’s performance than it would in a more geographically diversified portfolio. To the extent the Fund invests in foreign debt securities, such investments are sensitive to changes in interest rates. Additionally, investments in securities of foreign governments involve the risk that a foreign government may not be willing or able to pay interest or repay principal when due.

Eurozone Risk. A number of countries in the European Union (“EU”) have experienced severe economic and financial difficulties. As a result, financial markets in the EU have been subject to extreme volatility and declines in asset values and liquidity. Responses to these financial problems by European governments, central banks, and others, including austerity measures and reforms, may not work, may result in social unrest, and may limit future growth and economic recovery or have other unintended consequences. Further defaults or restructurings by governments and others of their debt could have additional adverse effects on economies, financial markets, and asset valuations around the world. To the extent that the Fund has exposure to European markets or to transactions tied to the value of the euro, these events could negatively affect the value and liquidity of the Fund’s investments.

Dividend Risk. Companies that issue dividend-yielding securities are not required to continue to pay dividends on such securities. Therefore, there is the possibility that such companies could reduce or eliminate the payment of dividends in the future.

Market Risk. The value of the Fund’s portfolio may decrease if the value of an individual company or security, or multiple companies or securities, in the portfolio decreases. Further, regardless of how well individual companies or securities perform, the value of the Fund’s portfolio could also decrease if there are deteriorating economic or market conditions. It is important to understand that the value of your investment may fall, sometimes sharply, in response to changes in the market, and you could lose money.

Investment Process Risk. The proprietary mathematical investment process used by INTECH may not achieve the desired results. There is a risk that INTECH’s method of identifying stocks with higher volatility than the named benchmark index or its method of identifying stocks that tend to move in the same or opposite direction relative to each other (correlation) will not result in selecting stocks with continuing volatility or the expected correlation. In INTECH’s history, which spans more than 25 years, INTECH’s mathematical investment process has experienced periods of both underperformance and outperformance relative to an identified benchmark. Even when the proprietary mathematical investment process is working appropriately, INTECH expects that there will be periods of underperformance relative to the benchmark. On an occasional basis, INTECH makes changes to its mathematical investment process. These changes may result in changes to the portfolio, might not provide the intended results, and may adversely impact the Fund’s performance.

Portfolio Turnover Risk. Increased portfolio turnover may result in higher costs, which may have a negative effect on the Fund’s performance. In addition, higher portfolio turnover may result in the acceleration of capital gains and the recognition of greater levels of short-term capital gains, which are taxed at ordinary federal income tax rates when distributed to shareholders.

Securities Lending Risk. The Fund may seek to earn additional income through lending its securities to certain qualified broker-dealers and institutions. There is the risk that when portfolio securities are lent, the securities may not be returned on a timely basis, and the Fund may experience delays and costs in recovering the security or gaining access to the collateral provided to the Fund to collateralize the loan. If the Fund is unable to recover a security on loan, the Fund may use the collateral to purchase replacement securities in the market. There is a risk that the value of the collateral could decrease below the cost of the replacement security by the time the replacement investment is made, resulting in a loss to the Fund.

An investment in the Fund is not a bank deposit and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency.

PERFORMANCE INFORMATION

The following information provides some indication of the risks of investing in the Fund by showing how the Fund’s performance has varied over time. The bar chart depicts the Fund’s performance during the period indicated. The bar chart figures do not include any applicable sales charges that an investor may pay when they buy or sell Class A Shares or Class C Shares of the Fund. If sales charges were included, the returns would be lower. The table compares the Fund’s average annual returns for the periods indicated to broad-based securities market indices. The indices are not actively managed and are not available for direct investment. All figures assume reinvestment of dividends and distributions. For certain periods, the Fund’s performance reflects the effect of expense waivers. Without the effect of these expense waivers, the performance shown would have been lower.

The Fund’s past performance (before and after taxes) does not necessarily indicate how it will perform in the future. Updated performance information is available at janus.com/advisor/mutual-funds or by calling 1-877-335-2687.

Annual Total Returns for Class I Shares (calendar year-end)

Best Quarter:  Third Quarter 2012  5.98%          Worst Quarter:  Second Quarter 2012  −2.66%

The Fund’s year-to-date return as of the calendar quarter ended September 30, 2013 was 12.88%.

Average Annual Total Returns (periods ended 12/31/12)

Average Annual Total Returns INTECH Global Dividend Fund Class A, C, S, I, T Shares	Column	Label		1 Year	Since Inception	Inception Date
Class I Return Before Taxes	Class I Shares	Return Before Taxes		12.35%	15.14%	Dec. 15, 2011
Class I Return After Taxes on Distributions	Class I Shares	Return After Taxes on Distributions		11.63%	14.39%	Dec. 15, 2011
Class I Return After Taxes on Distributions and Sale of Fund Shares	Class I Shares	Return After Taxes on Distributions and Sale of Fund Shares		8.63%	12.67%	Dec. 15, 2011
Class A Return Before Taxes	Class A Shares	Return Before Taxes	[1]	5.59%	8.50%	Dec. 15, 2011
Class C Return Before Taxes	Class C Shares	Return Before Taxes	[2]	10.10%	13.98%	Dec. 15, 2011
Class S Return Before Taxes	Class S Shares	Return Before Taxes		11.73%	14.53%	Dec. 15, 2011
Class T Return Before Taxes	Class T Shares	Return Before Taxes		12.05%	14.84%	Dec. 15, 2011
Morgan Stanley Capital International World Index℠ (net of foreign withholding taxes) (reflects no deduction for expenses, fees, or taxes, except foreign withholding taxes)		Morgan Stanley Capital International World IndexSM (net of foreign withholding taxes)		15.83%	19.02%	Dec. 15, 2011
Morgan Stanley Capital International World High Dividend Yield Index (net of foreign withholding taxes) (reflects no deduction for expenses, fees, or taxes, except foreign withholding taxes)		Morgan Stanley Capital International World High Dividend Yield Index (net of foreign withholding taxes)		12.24%	15.80%	Dec. 15, 2011

After-tax returns are calculated using the historically highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes. Actual after-tax returns depend on your individual tax situation and may differ from those shown in the preceding table. The after-tax return information shown above does not apply to Fund shares held through a tax-deferred account, such as a 401(k) plan or an IRA.

After-tax returns are only shown for Class I Shares of the Fund. After-tax returns for the other classes of Shares will vary from those shown for Class I Shares due to varying sales charges (as applicable), fees, and expenses among the classes.

[1] Janus Capital has contractually agreed to waive its investment advisory fee and/or reimburse Fund expenses to the extent that the Fund’s total annual fund operating expenses (excluding the distribution and shareholder servicing fees – applicable to Class A Shares, Class C Shares, and Class S Shares; administrative services fees payable pursuant to the Transfer Agency Agreement; brokerage commissions; interest; dividends; taxes; acquired fund fees and expenses; and extraordinary expenses) exceed 0.50% until at least November 1, 2014. The contractual waiver may be terminated or modified prior to this date only at the discretion of the Board of Trustees. For a period of three years subsequent to the Fund’s commencement of operations (December 15, 2011), Janus Capital may recover from the Fund fees and expenses previously waived or reimbursed, which could then be considered a deferral, if the Fund’s expense ratio, including recovered expenses, falls below the expense limit.

[1] Calculated assuming maximum permitted sales loads.

[2] The one year return is calculated to include the contingent deferred sales charge.

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Label	Element	Value
Risk/Return:	rr_RiskReturnAbstract
Registrant Name	dei_EntityRegistrantName	JANUS INVESTMENT FUND
Prospectus Date	rr_ProspectusDate	Oct. 28, 2013
Perkins Large Cap Value Fund | Class D Shares
Risk/Return:	rr_RiskReturnAbstract
Risk/Return [Heading]	rr_RiskReturnHeading	FUND SUMMARY Perkins Large Cap Value Fund
Objective [Heading]	rr_ObjectiveHeading	INVESTMENT OBJECTIVE
Objective, Primary [Text Block]	rr_ObjectivePrimaryTextBlock	Perkins Large Cap Value Fund seeks capital appreciation.
Expense [Heading]	rr_ExpenseHeading	FEES AND EXPENSES OF THE FUND
Expense Narrative [Text Block]	rr_ExpenseNarrativeTextBlock	This table describes the fees and expenses that you may pay if you buy and hold Shares of the Fund.
Operating Expenses Caption [Text]	rr_OperatingExpensesCaption	ANNUAL FUND OPERATING EXPENSES (expenses that you pay each year as a percentage of the value of your investment)
Fee Waiver or Reimbursement over Assets, Date of Termination	rr_FeeWaiverOrReimbursementOverAssetsDateOfTermination	November 1, 2014
Portfolio Turnover [Heading]	rr_PortfolioTurnoverHeading	Portfolio Turnover:
Portfolio Turnover [Text Block]	rr_PortfolioTurnoverTextBlock	The Fund pays transaction costs, such as commissions, when it buys and sells securities (or “turns over” its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when Fund shares are held in a taxable account. These costs, which are not reflected in annual fund operating expenses or in the Example, affect the Fund’s performance. During the most recent fiscal year, the Fund’s portfolio turnover rate was 45% of the average value of its portfolio.
Portfolio Turnover, Rate	rr_PortfolioTurnoverRate	45.00%
Expense Example [Heading]	rr_ExpenseExampleHeading	EXAMPLE:
Expense Example by Year [Heading]	rr_ExpenseExampleByYearHeading	The Example assumes that you invest $10,000 in the Fund for the time periods indicated, reinvest all dividends and distributions, and then redeem all of your Shares at the end of each period. The Example also assumes that your investment has a 5% return each year and that the Fund’s operating expenses without waivers remain the same. Although your actual costs may be higher or lower, based on these assumptions your costs would be:
Expense Example Narrative [Text Block]	rr_ExpenseExampleNarrativeTextBlock	The following Example is based on expenses without waivers. The Example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds.
Strategy [Heading]	rr_StrategyHeading	PRINCIPAL INVESTMENT STRATEGIES
Strategy Narrative [Text Block]	rr_StrategyNarrativeTextBlock	The Fund pursues its investment objective by investing primarily in common stocks selected for their capital appreciation potential. The Fund primarily invests in the common stocks of large-sized companies whose stock prices the portfolio managers believe to be undervalued. The Fund invests, under normal circumstances, at least 80% of its net assets in equity securities of companies having, at the time of purchase, market capitalizations equal to or greater than the median market capitalization of companies included in the Russell 1000® Value Index. The market capitalizations within the index will vary, but as of June 30, 2013, they ranged from approximately $487 million to $422.5 billion, and the median market capitalization was $5.9 billion. The Fund may also invest in foreign equity and debt securities, which may include investments in emerging markets. The Fund may invest, under normal circumstances, up to 20% of its net assets in securities of companies having market capitalizations outside of the aforementioned market capitalization ranges. In addition, when the portfolio managers believe that market conditions are unfavorable for investing, or when they are otherwise unable to locate attractive investment opportunities, the Fund may invest up to 20% of its net assets in exchange-traded funds (“ETFs”), including commodity-related ETFs, cash, or similar investments. The Fund focuses on companies that have fallen out of favor with the market or that appear to be temporarily misunderstood by the investment community. The Fund’s portfolio managers generally look for companies with: strong balance sheets and solid recurring free cash flows attractive relative and absolute valuation ratios or that have underperformed recently favorable reward to risk characteristics The Fund may invest its assets in derivatives, which are instruments that have a value derived from, or directly linked to, an underlying asset, such as equity securities, fixed-income securities, commodities, currencies, interest rates, or market indices, as substitutes for securities in which the Fund invests. The Fund may invest in derivative instruments (by taking long and/or short positions) for different purposes, including hedging (to offset risks associated with an investment, currency exposure, or market conditions) and to earn income and enhance returns.
Risk [Heading]	rr_RiskHeading	PRINCIPAL INVESTMENT RISKS
Risk Narrative [Text Block]	rr_RiskNarrativeTextBlock	The biggest risk is that the Fund’s returns will vary, and you could lose money. The Fund is designed for long-term investors seeking an equity portfolio, including common stocks. Common stocks tend to be more volatile than many other investment choices. Value Investing Risk. Because different types of stocks tend to shift in and out of favor depending on market and economic conditions, “value” stocks may perform differently than other types of stocks and from the market as a whole, and can continue to be undervalued by the market for long periods of time. It is also possible that a value stock will never appreciate to the extent expected by the portfolio managers. When the Fund’s investments in cash or similar investments increase due to a lack of favorable investment opportunities or other extraordinary factors, the Fund may not participate in market advances or declines to the same extent that it would if the Fund had been fully invested. Market Risk. The value of the Fund’s portfolio may decrease if the value of an individual company or security, or multiple companies or securities, in the portfolio decreases or if the portfolio managers’ belief about a company’s intrinsic worth is incorrect. Further, regardless of how well individual companies or securities perform, the value of the Fund’s portfolio could also decrease if there are deteriorating economic or market conditions. It is important to understand that the value of your investment may fall, sometimes sharply, in response to changes in the market, and you could lose money. Foreign Exposure Risk. The Fund may have exposure to foreign markets as a result of its investments in foreign securities, including investments in emerging markets, which can be more volatile than the U.S. markets. As a result, its returns and net asset value may be affected to a large degree by fluctuations in currency exchange rates or political or economic conditions in a particular country. In some foreign markets, there may not be protection against failure by other parties to complete transactions. It may not be possible for the Fund to repatriate capital, dividends, interest, and other income from a particular country or governmental entity. In addition, a market swing in one or more countries or regions where the Fund has invested a significant amount of its assets may have a greater effect on the Fund’s performance than it would in a more geographically diversified portfolio. To the extent the Fund invests in foreign debt securities, such investments are sensitive to changes in interest rates. Additionally, investments in securities of foreign governments involve the risk that a foreign government may not be willing or able to pay interest or repay principal when due. Eurozone Risk. A number of countries in the European Union (“EU”) have experienced severe economic and financial difficulties. As a result, financial markets in the EU have been subject to extreme volatility and declines in asset values and liquidity. Responses to these financial problems by European governments, central banks, and others, including austerity measures and reforms, may not work, may result in social unrest, and may limit future growth and economic recovery or have other unintended consequences. Further defaults or restructurings by governments and others of their debt could have additional adverse effects on economies, financial markets, and asset valuations around the world. To the extent that the Fund has exposure to European markets or to transactions tied to the value of the euro, these events could negatively affect the value and liquidity of the Fund’s investments. Exchange-Traded Funds Risk. The Fund may invest in ETFs, which are typically open-end investment companies that are traded on a national securities exchange. ETFs typically incur fees, such as investment advisory fees and other operating expenses that are separate from those of the Fund, which will be indirectly paid by the Fund. As a result, the cost of investing in the Fund may be higher than the cost of investing directly in ETFs and may be higher than other mutual funds that invest directly in stocks and bonds. Further, the price movement of an ETF may fluctuate against the underlying securities or commodities it tracks and may result in a loss. Because the value of ETF shares depends on the demand in the market, the Fund may not be able to purchase or sell an ETF at the most optimal time, which could adversely affect the Fund’s performance. The ETFs in which the Fund invests are subject to specific risks, depending on the investment strategy of the ETF. In turn, the Fund will be subject to substantially the same risks as those associated with direct exposure to the securities or commodities held by the ETF. Because the Fund may invest in a broad range of ETFs, such risks may include, but are not limited to, leverage risk, foreign exposure risk, and commodities risk. Derivatives Risk. Derivatives can be highly volatile and involve risks in addition to the risks of the underlying referenced securities. Gains or losses from a derivative investment can be substantially greater than the derivative’s original cost, and can therefore involve leverage. Leverage may cause the Fund to be more volatile than if it had not used leverage. Derivatives can be less liquid than other types of investments and entail the risk that the counterparty will default on its payment obligations. An investment in the Fund is not a bank deposit and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency.
Risk Lose Money [Text]	rr_RiskLoseMoney	The biggest risk is that the Fund’s returns will vary, and you could lose money.
Risk Not Insured Depository Institution [Text]	rr_RiskNotInsuredDepositoryInstitution	An investment in the Fund is not a bank deposit and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency.
Bar Chart and Performance Table [Heading]	rr_BarChartAndPerformanceTableHeading	PERFORMANCE INFORMATION
Performance Narrative [Text Block]	rr_PerformanceNarrativeTextBlock	The following information provides some indication of the risks of investing in the Fund by showing how the Fund’s performance has varied over time. Class D Shares of the Fund commenced operations on February 16, 2010. The performance shown for Class D Shares for the period July 6, 2009 to February 16, 2010, reflects the performance of the Fund’s Class I Shares, calculated using the fees and expenses of Class D Shares, without the effect of any fee and expense limitations or waivers. Performance shown for the period prior to July 6, 2009, reflects the historical performance of the Janus Adviser Perkins Large Cap Value Fund’s (“JAD predecessor fund”) Class I Shares prior to the reorganization of Class I Shares of the JAD predecessor fund into Class I Shares of the Fund, calculated using the fees and expenses of Class D Shares, without the effect of any fee and expense limitations or waivers. If Class D Shares of the Fund had been available during periods prior to February 16, 2010, the performance shown may have been different. The performance shown for periods following the Fund’s commencement of Class D Shares reflects the fees and expenses of Class D Shares, net of any applicable fee and expense limitations or waivers. The bar chart depicts the change in performance from year to year during the periods indicated. The table compares the Fund’s average annual returns for the periods indicated to a broad-based securities market index. The index is not actively managed and is not available for direct investment. All figures assume reinvestment of dividends and distributions. For certain periods, the Fund’s performance reflects the effect of expense waivers. Without the effect of these expense waivers, the performance shown would have been lower. The Fund’s past performance (before and after taxes) does not necessarily indicate how it will perform in the future. Updated performance information is available at janus.com/allfunds or by calling 1-800-525-3713.
Performance Information Illustrates Variability of Returns [Text]	rr_PerformanceInformationIllustratesVariabilityOfReturns	The following information provides some indication of the risks of investing in the Fund by showing how the Fund’s performance has varied over time. The bar chart depicts the change in performance from year to year during the periods indicated.
Performance Additional Market Index [Text]	rr_PerformanceAdditionalMarketIndex	The table compares the Fund’s average annual returns for the periods indicated to a broad-based securities market index. The index is not actively managed and is not available for direct investment. All figures assume reinvestment of dividends and distributions.
Performance Availability Phone [Text]	rr_PerformanceAvailabilityPhone	1-800-525-3713
Performance Availability Website Address [Text]	rr_PerformanceAvailabilityWebSiteAddress	janus.com/allfunds
Performance Past Does Not Indicate Future [Text]	rr_PerformancePastDoesNotIndicateFuture	The Fund’s past performance (before and after taxes) does not necessarily indicate how it will perform in the future.
Bar Chart [Heading]	rr_BarChartHeading	Annual Total Returns for Class D Shares (calendar year-end)
Bar Chart Closing [Text Block]	rr_BarChartClosingTextBlock	Best Quarter:  Second Quarter 2009  15.02%          Worst Quarter:  Third Quarter 2011  −14.77%
Year to Date Return, Label	rr_YearToDateReturnLabel	The Fund’s year-to-date return as of the calendar quarter ended September 30, 2013 was 17.90%.
Performance Table Heading	rr_PerformanceTableHeading	Average Annual Total Returns (periods ended 12/31/12)
Performance Table Uses Highest Federal Rate	rr_PerformanceTableUsesHighestFederalRate	After-tax returns are calculated using the historically highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes.
Performance Table Not Relevant to Tax Deferred	rr_PerformanceTableNotRelevantToTaxDeferred	Actual after-tax returns depend on your individual tax situation and may differ from those shown in the preceding table. The after-tax return information shown above does not apply to Fund shares held through a tax-deferred account, such as a 401(k) plan or an IRA.
Performance Table Narrative	rr_PerformanceTableNarrativeTextBlock	The Russell 1000® Value Index measures the performance of those Russell 1000® companies with lower price-to-book ratios and lower forecasted growth values. This index is used to calculate the performance fee adjustment. After-tax returns are calculated using distributions for the Fund’s Class D Shares for the periods following February 16, 2010; for the Fund’s Class I Shares for the period following July 6, 2009; and for the JAD predecessor fund’s Class I Shares for the period prior to July 6, 2009. If Class D Shares of the Fund had been available during these earlier periods, distributions may have been different and thus, after-tax returns may have been different from those shown. After-tax returns are calculated using the historically highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes. Actual after-tax returns depend on your individual tax situation and may differ from those shown in the preceding table. The after-tax return information shown above does not apply to Fund shares held through a tax-deferred account, such as a 401(k) plan or an IRA.
Performance Table Closing [Text Block]	rr_PerformanceTableClosingTextBlock	Updated performance information is available at janus.com/allfunds or by calling 1-800-525-3713.
Perkins Large Cap Value Fund | Class D Shares | Class D
Risk/Return:	rr_RiskReturnAbstract
Operating Expenses Column [Text]	rr_OperatingExpensesColumnName	Class D
Management Fees (may adjust up or down)	rr_ManagementFeesOverAssets	0.52%
Other Expenses	rr_OtherExpensesOverAssets	0.32%
Total Annual Fund Operating Expenses	rr_ExpensesOverAssets	0.84%	[1]
Fee Waiver	rr_FeeWaiverOrReimbursementOverAssets	0.08%	[1]
Total Annual Fund Operating Expenses After Fee Waiver	rr_NetExpensesOverAssets	0.76%	[1]
Expense Example, By Year, Column [Text]	rr_ExpenseExampleByYearColumnName	Class D Shares
1 Year	rr_ExpenseExampleYear01	$ 86
3 Years	rr_ExpenseExampleYear03	268
5 Years	rr_ExpenseExampleYear05	466
10 Years	rr_ExpenseExampleYear10	$ 1,037
2009	rr_AnnualReturn2009	23.61%
2010	rr_AnnualReturn2010	11.94%
2011	rr_AnnualReturn2011	(0.37%)
2012	rr_AnnualReturn2012	13.12%
Bar Chart, Year to Date Return, Date	rr_BarChartYearToDateReturnDate	Sep. 30, 2013
Bar Chart, Year to Date Return	rr_BarChartYearToDateReturn	17.90%
Highest Quarterly Return, Label	rr_HighestQuarterlyReturnLabel	Best Quarter:
Highest Quarterly Return, Date	rr_BarChartHighestQuarterlyReturnDate	Jun. 30, 2009
Highest Quarterly Return	rr_BarChartHighestQuarterlyReturn	15.02%
Lowest Quarterly Return, Label	rr_LowestQuarterlyReturnLabel	Worst Quarter:
Lowest Quarterly Return, Date	rr_BarChartLowestQuarterlyReturnDate	Sep. 30, 2011
Lowest Quarterly Return	rr_BarChartLowestQuarterlyReturn	(14.77%)
Perkins Large Cap Value Fund | Class D Shares | Return Before Taxes | Class D
Risk/Return:	rr_RiskReturnAbstract
Column	rr_AverageAnnualReturnColumnName	Class D Shares
Label	rr_AverageAnnualReturnLabel	Return Before Taxes
1 Year	rr_AverageAnnualReturnYear01	13.12%
Since Inception of Predecessor Fund	rr_AverageAnnualReturnSinceInception	11.75%
Inception Date	rr_AverageAnnualReturnInceptionDate	Dec. 31, 2008
Perkins Large Cap Value Fund | Class D Shares | Return After Taxes on Distributions | Class D
Risk/Return:	rr_RiskReturnAbstract
Column	rr_AverageAnnualReturnColumnName	Class D Shares
Label	rr_AverageAnnualReturnLabel	Return After Taxes on Distributions
1 Year	rr_AverageAnnualReturnYear01	12.56%
Since Inception of Predecessor Fund	rr_AverageAnnualReturnSinceInception	11.01%
Inception Date	rr_AverageAnnualReturnInceptionDate	Dec. 31, 2008
Perkins Large Cap Value Fund | Class D Shares | Return After Taxes on Distributions and Sale of Fund Shares | Class D
Risk/Return:	rr_RiskReturnAbstract
Column	rr_AverageAnnualReturnColumnName	Class D Shares
Label	rr_AverageAnnualReturnLabel	Return After Taxes on Distributions and Sale of Fund Shares
1 Year	rr_AverageAnnualReturnYear01	9.29%
Since Inception of Predecessor Fund	rr_AverageAnnualReturnSinceInception	10.00%
Inception Date	rr_AverageAnnualReturnInceptionDate	Dec. 31, 2008
Perkins Large Cap Value Fund | Class D Shares | Russell 1000® Value Index (reflects no deduction for expenses, fees, or taxes)
Risk/Return:	rr_RiskReturnAbstract
Label	rr_AverageAnnualReturnLabel	Russell 1000® Value Index
1 Year	rr_AverageAnnualReturnYear01	17.51%
Since Inception of Predecessor Fund	rr_AverageAnnualReturnSinceInception	13.01%
Inception Date	rr_AverageAnnualReturnInceptionDate	Dec. 31, 2008

[1] Janus Capital has contractually agreed to waive its investment advisory fee and/or reimburse Fund expenses to the extent that the Fund’s total annual fund operating expenses (excluding any performance adjustments to management fees, administrative services fees payable pursuant to the Transfer Agency Agreement, brokerage commissions, interest, dividends, taxes, acquired fund fees and expenses, and extraordinary expenses) exceed 0.75% until at least November 1, 2014. The contractual waiver may be terminated or modified prior to this date only at the discretion of the Board of Trustees.

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Perkins Mid Cap Value Fund | Class A, C, S, I, N, R, T Shares

FUND SUMMARY

Perkins Mid Cap Value Fund

INVESTMENT OBJECTIVE

Perkins Mid Cap Value Fund seeks capital appreciation.

FEES AND EXPENSES OF THE FUND

This table describes the fees and expenses that you may pay if you buy and hold Shares of the Fund. Each share class has different expenses, but represents an investment in the same Fund.

For Class A Shares, you may qualify for sales charge discounts if you and your family invest, or agree to invest in the future, at least $50,000 in the Fund or in other Janus mutual funds. More information about these and other discounts, as well as eligibility requirements for each share class, is available from your financial professional and in the “Purchases” section on page 66 of the Fund’s Prospectus and in the “Purchases” section on page 70 of the Fund’s Statement of Additional Information.

SHAREHOLDER FEES
(fees paid directly from your investment)

Shareholder Fees Perkins Mid Cap Value Fund Class A, C, S, I, N, R, T Shares	Class A	Class C	Class S	Class I	Class N	Class R	Class T
Shareholder Fees Column [Text]	Class A	Class C	Class S	Class I	Class N	Class R	Class T
Maximum Sales Charge (load) Imposed on Purchases (as a percentage of offering price)	5.75%	none	none	none	none	none	none
Maximum Deferred Sales Charge (load) (as a percentage of the lower of original purchase price or redemption proceeds)	none	1.00%	none	none	none	none	none

ANNUAL FUND OPERATING EXPENSES
(expenses that you pay each year as a percentage of the value of your investment)

Annual Fund Operating Expenses Perkins Mid Cap Value Fund Class A, C, S, I, N, R, T Shares	Class A	Class C	Class S	Class I	Class N	Class R	Class T
Operating Expenses Column [Text]	Class A	Class C	Class S	Class I	Class N	Class R	Class T
Management Fees (may adjust up or down)	0.48%	0.48%	0.48%	0.48%	0.48%	0.48%	0.48%
Distribution/Service (12b-1) Fees	0.25%	1.00%	0.25%	none	none	0.50%	none
Other Expenses	0.27%	0.24%	0.29%	0.15%	0.04%	0.28%	0.29%
Total Annual Fund Operating Expenses	1.00%	1.72%	1.02%	0.63%	0.52%	1.26%	0.77%

EXAMPLE:

The Example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds.

The Example assumes that you invest $10,000 in the Fund for the time periods indicated and reinvest all dividends and distributions. The Example also assumes that your investment has a 5% return each year and that the Fund’s operating expenses remain the same. Although your actual costs may be higher or lower, based on these assumptions your costs would be:

If Shares are redeemed:

Expense Example Perkins Mid Cap Value Fund Class A, C, S, I, N, R, T Shares (USD $)	Expense Example, By Year, Column [Text]	1 Year	3 Years	5 Years	10 Years
Class A	Class A Shares	671	875	1,096	1,729
Class C	Class C Shares	275	542	933	2,030
Class S	Class S Shares	104	325	563	1,248
Class I	Class I Shares	64	202	351	786
Class N	Class N Shares	53	167	291	653
Class R	Class R Shares	128	400	692	1,523
Class T	Class T Shares	79	246	428	954

If Shares are not redeemed:

Expense Example, No Redemption Perkins Mid Cap Value Fund Class A, C, S, I, N, R, T Shares (USD $)	Expense Example, No Redemption, By Year, Column [Text]	1 Year	3 Years	5 Years	10 Years
Class A	Class A Shares	671	875	1,096	1,729
Class C	Class C Shares	175	542	933	2,030
Class S	Class S Shares	104	325	563	1,248
Class I	Class I Shares	64	202	351	786
Class N	Class N Shares	53	167	291	653
Class R	Class R Shares	128	400	692	1,523
Class T	Class T Shares	79	246	428	954

Portfolio Turnover:

The Fund pays transaction costs, such as commissions, when it buys and sells securities (or “turns over” its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when Fund shares are held in a taxable account. These costs, which are not reflected in annual fund operating expenses or in the Example, affect the Fund’s performance. During the most recent fiscal year, the Fund’s portfolio turnover rate was 60% of the average value of its portfolio.

PRINCIPAL INVESTMENT STRATEGIES

The Fund pursues its investment objective by investing primarily in common stocks selected for their capital appreciation potential. The Fund primarily invests in the common stocks of mid-sized companies whose stock prices the portfolio managers believe to be undervalued. The Fund invests, under normal circumstances, at least 80% of its net assets in equity securities of companies whose market capitalization falls, at the time of purchase, within the 12-month average of the capitalization range of the Russell Midcap^® Value Index. This average is updated monthly. The market capitalizations within the index will vary, but as of June 30, 2013, they ranged from approximately $487 million to $30.3 billion. The Fund may also invest in foreign equity and debt securities, which may include investments in emerging markets. The Fund may invest, under normal circumstances, up to 20% of its net assets in securities of companies having market capitalizations outside of the aforementioned market capitalization ranges. In addition, when the portfolio managers believe that market conditions are unfavorable for investing, or when they are otherwise unable to locate attractive investment opportunities, the Fund may invest up to 20% of its net assets in cash or similar investments.

The Fund focuses on companies that have fallen out of favor with the market or that appear to be temporarily misunderstood by the investment community. The Fund’s portfolio managers generally look for companies with:

• strong balance sheets and solid recurring free cash flows
• attractive relative and absolute valuation ratios or that have underperformed recently
• favorable reward to risk characteristics

The Fund may invest in equity and debt securities of real estate-related companies. Such companies may include those in the real estate industry or real estate-related industries. These securities may include common stocks, preferred stocks, and other equity securities, including, but not limited to, mortgage-backed securities, real estate-backed securities, securities of real estate investment trusts (“REITs”) and similar REIT-like entities. A REIT is a trust that invests in real estate-related projects, such as properties, mortgage loans, and construction loans. REITs are generally categorized as equity, mortgage, or hybrid REITs. A REIT may be listed on an exchange or traded over-the-counter.

The Fund may also invest its assets in derivatives, which are instruments that have a value derived from, or directly linked to, an underlying asset, such as equity securities, fixed-income securities, commodities, currencies, interest rates, or market indices. The Fund from time to time may buy and sell put and call options, particularly on market indices, for hedging purposes (to offset risks associated with an investment, currency exposure, or market conditions) and to enhance returns. The Fund’s exposure to derivatives will vary, is not limited to those derivatives listed, and could be significant at times. For purposes of meeting its 80% investment policy, the Fund may include derivatives that have characteristics similar to the securities in which the Fund may directly invest.

PRINCIPAL INVESTMENT RISKS

The biggest risk is that the Fund’s returns will vary, and you could lose money. The Fund is designed for long-term investors seeking an equity portfolio, including common stocks. Common stocks tend to be more volatile than many other investment choices.

Value Investing Risk. Because different types of stocks tend to shift in and out of favor depending on market and economic conditions, “value” stocks may perform differently than other types of stocks and from the market as a whole, and can continue to be undervalued by the market for long periods of time. It is also possible that a value stock will never appreciate to the extent expected by the portfolio managers. When the Fund’s investments in cash or similar investments increase due to a lack of favorable investment opportunities or other extraordinary factors, the Fund may not participate in market advances or declines to the same extent that it would if the Fund had been fully invested.

Market Risk. The value of the Fund’s portfolio may decrease if the value of an individual company or security, or multiple companies or securities, in the portfolio decreases or if the portfolio managers’ belief about a company’s intrinsic worth is incorrect. Further, regardless of how well individual companies or securities perform, the value of the Fund’s portfolio could also decrease if there are deteriorating economic or market conditions. It is important to understand that the value of your investment may fall, sometimes sharply, in response to changes in the market, and you could lose money.

Mid-Sized Companies Risk. The Fund’s investments in securities issued by mid-sized companies may involve greater risks than are customarily associated with larger, more established companies. Securities issued by mid-sized companies tend to be more volatile than securities issued by larger or more established companies and may underperform as compared to the securities of larger companies.

Real Estate Securities Risk. The Fund’s performance may be affected by the risks associated with investments in real estate-related companies. The value of real estate-related companies’ securities is sensitive to changes in real estate values and rental income, property taxes, interest rates, tax and regulatory requirements, supply and demand, and the management skill and creditworthiness of the company. Investments in REITs involve the same risks as other real estate investments. In addition, a REIT could fail to qualify for tax-free pass-through of its income under the Internal Revenue Code or fail to maintain its exemption from registration under the Investment Company Act of 1940, as amended, which could produce adverse economic consequences for the REIT and its investors, including the Fund.

Foreign Exposure Risk. The Fund may have exposure to foreign markets as a result of its investments in foreign securities, including investments in emerging markets, which can be more volatile than the U.S. markets. As a result, its returns and net asset value may be affected to a large degree by fluctuations in currency exchange rates or political or economic conditions in a particular country. In some foreign markets, there may not be protection against failure by other parties to complete transactions. It may not be possible for the Fund to repatriate capital, dividends, interest, and other income from a particular country or governmental entity. In addition, a market swing in one or more countries or regions where the Fund has invested a significant amount of its assets may have a greater effect on the Fund’s performance than it would in a more geographically diversified portfolio. To the extent the Fund invests in foreign debt securities, such investments are sensitive to changes in interest rates. Additionally, investments in securities of foreign governments involve the risk that a foreign government may not be willing or able to pay interest or repay principal when due.

Derivatives Risk. Derivatives can be highly volatile and involve risks in addition to the risks of the underlying referenced securities. Gains or losses from a derivative investment can be substantially greater than the derivative’s original cost, and can therefore involve leverage. Leverage may cause the Fund to be more volatile than if it had not used leverage. Derivatives can be complex instruments and may involve analysis that differs from that required for other investment types used by the Fund. If the value of a derivative does not correlate well with the particular market or other asset class to which the derivative is intended to provide exposure, the derivative may not produce the anticipated result. Derivatives can also reduce the opportunity for gain or result in losses by offsetting positive returns in other investments. Derivatives can be less liquid than other types of investments and entail the risk that the counterparty will default on its payment obligations. If the counterparty to a derivative transaction defaults, the Fund would risk the loss of the net amount of the payments that it contractually is entitled to receive. To the extent the Fund enters into short derivative positions, the Fund may be exposed to risks similar to those associated with short sales, including the risk that the Fund’s losses are theoretically unlimited.

An investment in the Fund is not a bank deposit and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency.

PERFORMANCE INFORMATION

The following information provides some indication of the risks of investing in the Fund by showing how the Fund’s performance has varied over time. Class T Shares (formerly named Class J Shares) of the Fund commenced operations with the Fund’s inception. Class A Shares, Class C Shares, Class S Shares, Class I Shares, and Class R Shares of the Fund commenced operations on July 6, 2009. Class N Shares of the Fund commenced operations on May 31, 2012.

• The performance shown for Class T Shares for periods following April 21, 2003, reflects the fees and expenses of Class T Shares in effect during the periods shown, net of any applicable fee and expense limitations or waivers. For the periods prior to April 21, 2003, the performance shown for Class T Shares reflects the historical performance of Berger Mid Cap Value Fund – Investor Shares (as a result of a prior reorganization of Berger Mid Cap Value Fund – Investor Shares into the Fund’s former Class J Shares).
• The performance shown for Class A Shares, Class C Shares, Class S Shares, and Class R Shares reflects the performance of the Fund’s Class J Shares (formerly named Investor Shares) from April 21, 2003 to July 6, 2009, calculated using the fees and expenses of each respective share class, without the effect of any fee and expense limitations or waivers. For periods prior to April 21, 2003, the performance shown for Class A Shares, Class C Shares, Class S Shares, and Class R Shares reflects the historical performance of Berger Mid Cap Value Fund – Investor Shares (as a result of a prior reorganization of Berger Mid Cap Value Fund – Investor Shares into the Fund’s former Class J Shares), calculated using the fees and expenses of each respective share class, without the effect of any fee and expense limitations or waivers.
• The performance shown for Class I Shares reflects the performance of the Fund’s Class J Shares (formerly named Investor Shares) from April 21, 2003 to July 6, 2009, calculated using the fees and expenses of Class J Shares, net of any applicable fee and expense limitations or waivers. For the periods prior to April 21, 2003, the performance shown for Class I Shares reflects the historical performance of Berger Mid Cap Value Fund – Investor Shares (as a result of a prior reorganization of Berger Mid Cap Value Fund – Investor Shares into the Fund’s former Class J Shares), calculated using the fees and expenses of Class J Shares, net of any applicable fee and expense limitations or waivers.
• The performance shown for Class N Shares reflects the performance of the Fund’s Class T Shares from July 6, 2009 to May 31, 2012, calculated using the fees and expenses of Class T Shares, net of any applicable fee and expense limitations or waivers. For the period from April 21, 2003 to July 6, 2009, the performance shown for Class N Shares reflects the performance of the Fund’s Class J Shares (formerly named Investor Shares), calculated using the fees and expenses of Class J Shares, net of any applicable fee and expense limitations or waivers. For the periods prior to April 21, 2003, the performance shown for Class N Shares reflects the historical performance of Berger Mid Cap Value Fund – Investor Shares (as a result of a prior reorganization of Berger Mid Cap Value Fund – Investor Shares into the Fund’s former Class J Shares), calculated using the fees and expenses of Class J Shares, net of any applicable fee and expense limitations or waivers.

If Class A Shares, Class C Shares, Class S Shares, Class I Shares, and Class R Shares of the Fund had been available during periods prior to July 6, 2009, or Class N Shares of the Fund had been available during periods prior to May 31, 2012, the performance shown for each respective share class may have been different. The performance shown for periods following the Fund’s commencement of Class A Shares, Class C Shares, Class S Shares, Class I Shares, Class N Shares, and Class R Shares reflects the fees and expenses of each respective share class, net of any applicable fee and expense limitations or waivers.

The bar chart depicts the change in performance from year to year during the periods indicated. The bar chart figures do not include any applicable sales charges that an investor may pay when they buy or sell Class A Shares or Class C Shares of the Fund. If sales charges were included, the returns would be lower. The table compares the Fund’s average annual returns for the periods indicated to a broad-based securities market index. The index is not actively managed and is not available for direct investment. All figures assume reinvestment of dividends and distributions. For certain periods, the Fund’s performance reflects the effect of expense waivers. Without the effect of these expense waivers, the performance shown would have been lower.

The Fund’s past performance (before and after taxes) does not necessarily indicate how it will perform in the future. Updated performance information is available at janus.com/advisor/mutual-funds or by calling 1-877-335-2687.

Annual Total Returns for Class T Shares (calendar year-end)

Best Quarter:  Second Quarter 2003  17.17%          Worst Quarter:  Fourth Quarter 2008  −19.63%

The Fund’s year-to-date return as of the calendar quarter ended September 30, 2013 was 17.43%.

Average Annual Total Returns (periods ended 12/31/12)

Average Annual Total Returns Perkins Mid Cap Value Fund Class A, C, S, I, N, R, T Shares	Column	Label		1 Year	5 Years	10 Years	Since Inception of Predecessor Fund	Inception Date
Class T Return Before Taxes	Class T Shares	Return Before Taxes		10.32%	3.18%	10.17%	11.66%	Aug. 12, 1998
Class T Return After Taxes on Distributions	Class T Shares	Return After Taxes on Distributions		9.63%	2.53%	8.99%	10.26%	Aug. 12, 1998
Class T Return After Taxes on Distributions and Sale of Fund Shares	Class T Shares	Return After Taxes on Distributions and Sale of Fund Shares	[1]	7.65%	2.60%	8.67%	9.89%	Aug. 12, 1998
Class A Return Before Taxes	Class A Shares	Return Before Taxes	[2]	3.75%	1.77%	9.31%	11.05%	Aug. 12, 1998
Class C Return Before Taxes	Class C Shares	Return Before Taxes	[3]	8.20%	2.21%	9.17%	10.79%	Aug. 12, 1998
Class S Return Before Taxes	Class S Shares	Return Before Taxes		9.99%	2.89%	9.84%	11.41%	Aug. 12, 1998
Class I Return Before Taxes	Class I Shares	Return Before Taxes		10.41%	3.18%	10.17%	11.66%	Aug. 12, 1998
Class N Return Before Taxes	Class N Shares	Return Before Taxes		10.32%	3.18%	10.17%	11.66%	Aug. 12, 1998
Class R Return Before Taxes	Class R Shares	Return Before Taxes		9.72%	2.62%	9.57%	11.18%	Aug. 12, 1998
Russell Midcap® Value Index (reflects no deduction for expenses, fees, or taxes)		Russell Midcap® Value Index		18.51%	3.79%	10.63%	8.42%	Aug. 12, 1998

The Russell Midcap^® Value Index measures the performance of those Russell Midcap^® companies with lower price-to-book ratios and lower forecasted growth values. The stocks are also members of the Russell 1000^® Value Index. This index is used to calculate the performance fee adjustment.

After-tax returns are calculated using distributions for the Fund's Class T Shares (formerly named Class J Shares) for the periods following April 21, 2003; and for Berger Mid Cap Value Fund - Investor Shares for periods prior to April 21, 2003. If Class T Shares of the Fund had been available during the periods prior to April 21, 2003, distributions may have been different and thus, after-tax returns may have been different from those shown. After-tax returns are calculated using the historically highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes. Actual after-tax returns depend on your individual tax situation and may differ from those shown in the preceding table. The after-tax return information shown above does not apply to Fund shares held through a tax-deferred account, such as a 401(k) plan or an IRA.

After-tax returns are only shown for Class T Shares of the Fund. After-tax returns for the other classes of Shares will vary from those shown for Class T Shares due to varying sales charges (as applicable), fees, and expenses among the classes.

[1] If the Fund incurs a loss, which generates a tax benefit, the Return After Taxes on Distributions and Sale of Fund Shares may exceed the Fund's other return figures.

[2] Calculated assuming maximum permitted sales loads.

[3] The one year return is calculated to include the contingent deferred sales charge.

XML

Label	Element	Value
Risk/Return:	rr_RiskReturnAbstract
Registrant Name	dei_EntityRegistrantName	JANUS INVESTMENT FUND
Prospectus Date	rr_ProspectusDate	Oct. 28, 2013
Perkins Mid Cap Value Fund | Class A, C, S, I, N, R, T Shares
Risk/Return:	rr_RiskReturnAbstract
Risk/Return [Heading]	rr_RiskReturnHeading	FUND SUMMARY Perkins Mid Cap Value Fund
Objective [Heading]	rr_ObjectiveHeading	INVESTMENT OBJECTIVE
Objective, Primary [Text Block]	rr_ObjectivePrimaryTextBlock	Perkins Mid Cap Value Fund seeks capital appreciation.
Expense [Heading]	rr_ExpenseHeading	FEES AND EXPENSES OF THE FUND
Expense Narrative [Text Block]	rr_ExpenseNarrativeTextBlock	This table describes the fees and expenses that you may pay if you buy and hold Shares of the Fund. Each share class has different expenses, but represents an investment in the same Fund.
Shareholder Fees Caption [Text]	rr_ShareholderFeesCaption	SHAREHOLDER FEES (fees paid directly from your investment)
Operating Expenses Caption [Text]	rr_OperatingExpensesCaption	ANNUAL FUND OPERATING EXPENSES (expenses that you pay each year as a percentage of the value of your investment)
Portfolio Turnover [Heading]	rr_PortfolioTurnoverHeading	Portfolio Turnover:
Portfolio Turnover [Text Block]	rr_PortfolioTurnoverTextBlock	The Fund pays transaction costs, such as commissions, when it buys and sells securities (or “turns over” its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when Fund shares are held in a taxable account. These costs, which are not reflected in annual fund operating expenses or in the Example, affect the Fund’s performance. During the most recent fiscal year, the Fund’s portfolio turnover rate was 60% of the average value of its portfolio.
Portfolio Turnover, Rate	rr_PortfolioTurnoverRate	60.00%
Expense Breakpoint Discounts [Text]	rr_ExpenseBreakpointDiscounts	For Class A Shares, you may qualify for sales charge discounts if you and your family invest, or agree to invest in the future, at least $50,000 in the Fund or in other Janus mutual funds. More information about these and other discounts, as well as eligibility requirements for each share class, is available from your financial professional and in the “Purchases” section on page 66 of the Fund’s Prospectus and in the “Purchases” section on page 70 of the Fund’s Statement of Additional Information.
Expense Breakpoint, Minimum Investment Required [Amount]	rr_ExpenseBreakpointMinimumInvestmentRequiredAmount	$ 50,000
Expense Example [Heading]	rr_ExpenseExampleHeading	EXAMPLE:
Expense Example by Year [Heading]	rr_ExpenseExampleByYearHeading	The Example assumes that you invest $10,000 in the Fund for the time periods indicated and reinvest all dividends and distributions. The Example also assumes that your investment has a 5% return each year and that the Fund’s operating expenses remain the same. Although your actual costs may be higher or lower, based on these assumptions your costs would be:
Expense Example Narrative [Text Block]	rr_ExpenseExampleNarrativeTextBlock	The Example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds.
Expense Example by, Year, Caption [Text]	rr_ExpenseExampleByYearCaption	If Shares are redeemed:
Expense Example, No Redemption, By Year, Caption [Text]	rr_ExpenseExampleNoRedemptionByYearCaption	If Shares are not redeemed:
Strategy [Heading]	rr_StrategyHeading	PRINCIPAL INVESTMENT STRATEGIES
Strategy Narrative [Text Block]	rr_StrategyNarrativeTextBlock	The Fund pursues its investment objective by investing primarily in common stocks selected for their capital appreciation potential. The Fund primarily invests in the common stocks of mid-sized companies whose stock prices the portfolio managers believe to be undervalued. The Fund invests, under normal circumstances, at least 80% of its net assets in equity securities of companies whose market capitalization falls, at the time of purchase, within the 12-month average of the capitalization range of the Russell Midcap® Value Index. This average is updated monthly. The market capitalizations within the index will vary, but as of June 30, 2013, they ranged from approximately $487 million to $30.3 billion. The Fund may also invest in foreign equity and debt securities, which may include investments in emerging markets. The Fund may invest, under normal circumstances, up to 20% of its net assets in securities of companies having market capitalizations outside of the aforementioned market capitalization ranges. In addition, when the portfolio managers believe that market conditions are unfavorable for investing, or when they are otherwise unable to locate attractive investment opportunities, the Fund may invest up to 20% of its net assets in cash or similar investments. The Fund focuses on companies that have fallen out of favor with the market or that appear to be temporarily misunderstood by the investment community. The Fund’s portfolio managers generally look for companies with: strong balance sheets and solid recurring free cash flows attractive relative and absolute valuation ratios or that have underperformed recently favorable reward to risk characteristics The Fund may invest in equity and debt securities of real estate-related companies. Such companies may include those in the real estate industry or real estate-related industries. These securities may include common stocks, preferred stocks, and other equity securities, including, but not limited to, mortgage-backed securities, real estate-backed securities, securities of real estate investment trusts (“REITs”) and similar REIT-like entities. A REIT is a trust that invests in real estate-related projects, such as properties, mortgage loans, and construction loans. REITs are generally categorized as equity, mortgage, or hybrid REITs. A REIT may be listed on an exchange or traded over-the-counter. The Fund may also invest its assets in derivatives, which are instruments that have a value derived from, or directly linked to, an underlying asset, such as equity securities, fixed-income securities, commodities, currencies, interest rates, or market indices. The Fund from time to time may buy and sell put and call options, particularly on market indices, for hedging purposes (to offset risks associated with an investment, currency exposure, or market conditions) and to enhance returns. The Fund’s exposure to derivatives will vary, is not limited to those derivatives listed, and could be significant at times. For purposes of meeting its 80% investment policy, the Fund may include derivatives that have characteristics similar to the securities in which the Fund may directly invest.
Risk [Heading]	rr_RiskHeading	PRINCIPAL INVESTMENT RISKS
Risk Narrative [Text Block]	rr_RiskNarrativeTextBlock	The biggest risk is that the Fund’s returns will vary, and you could lose money. The Fund is designed for long-term investors seeking an equity portfolio, including common stocks. Common stocks tend to be more volatile than many other investment choices. Value Investing Risk. Because different types of stocks tend to shift in and out of favor depending on market and economic conditions, “value” stocks may perform differently than other types of stocks and from the market as a whole, and can continue to be undervalued by the market for long periods of time. It is also possible that a value stock will never appreciate to the extent expected by the portfolio managers. When the Fund’s investments in cash or similar investments increase due to a lack of favorable investment opportunities or other extraordinary factors, the Fund may not participate in market advances or declines to the same extent that it would if the Fund had been fully invested. Market Risk. The value of the Fund’s portfolio may decrease if the value of an individual company or security, or multiple companies or securities, in the portfolio decreases or if the portfolio managers’ belief about a company’s intrinsic worth is incorrect. Further, regardless of how well individual companies or securities perform, the value of the Fund’s portfolio could also decrease if there are deteriorating economic or market conditions. It is important to understand that the value of your investment may fall, sometimes sharply, in response to changes in the market, and you could lose money. Mid-Sized Companies Risk. The Fund’s investments in securities issued by mid-sized companies may involve greater risks than are customarily associated with larger, more established companies. Securities issued by mid-sized companies tend to be more volatile than securities issued by larger or more established companies and may underperform as compared to the securities of larger companies. Real Estate Securities Risk. The Fund’s performance may be affected by the risks associated with investments in real estate-related companies. The value of real estate-related companies’ securities is sensitive to changes in real estate values and rental income, property taxes, interest rates, tax and regulatory requirements, supply and demand, and the management skill and creditworthiness of the company. Investments in REITs involve the same risks as other real estate investments. In addition, a REIT could fail to qualify for tax-free pass-through of its income under the Internal Revenue Code or fail to maintain its exemption from registration under the Investment Company Act of 1940, as amended, which could produce adverse economic consequences for the REIT and its investors, including the Fund. Foreign Exposure Risk. The Fund may have exposure to foreign markets as a result of its investments in foreign securities, including investments in emerging markets, which can be more volatile than the U.S. markets. As a result, its returns and net asset value may be affected to a large degree by fluctuations in currency exchange rates or political or economic conditions in a particular country. In some foreign markets, there may not be protection against failure by other parties to complete transactions. It may not be possible for the Fund to repatriate capital, dividends, interest, and other income from a particular country or governmental entity. In addition, a market swing in one or more countries or regions where the Fund has invested a significant amount of its assets may have a greater effect on the Fund’s performance than it would in a more geographically diversified portfolio. To the extent the Fund invests in foreign debt securities, such investments are sensitive to changes in interest rates. Additionally, investments in securities of foreign governments involve the risk that a foreign government may not be willing or able to pay interest or repay principal when due. Derivatives Risk. Derivatives can be highly volatile and involve risks in addition to the risks of the underlying referenced securities. Gains or losses from a derivative investment can be substantially greater than the derivative’s original cost, and can therefore involve leverage. Leverage may cause the Fund to be more volatile than if it had not used leverage. Derivatives can be complex instruments and may involve analysis that differs from that required for other investment types used by the Fund. If the value of a derivative does not correlate well with the particular market or other asset class to which the derivative is intended to provide exposure, the derivative may not produce the anticipated result. Derivatives can also reduce the opportunity for gain or result in losses by offsetting positive returns in other investments. Derivatives can be less liquid than other types of investments and entail the risk that the counterparty will default on its payment obligations. If the counterparty to a derivative transaction defaults, the Fund would risk the loss of the net amount of the payments that it contractually is entitled to receive. To the extent the Fund enters into short derivative positions, the Fund may be exposed to risks similar to those associated with short sales, including the risk that the Fund’s losses are theoretically unlimited. An investment in the Fund is not a bank deposit and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency.
Risk Lose Money [Text]	rr_RiskLoseMoney	The biggest risk is that the Fund's returns will vary, and you could lose money.
Risk Not Insured Depository Institution [Text]	rr_RiskNotInsuredDepositoryInstitution	An investment in the Fund is not a bank deposit and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency.
Bar Chart and Performance Table [Heading]	rr_BarChartAndPerformanceTableHeading	PERFORMANCE INFORMATION
Performance Narrative [Text Block]	rr_PerformanceNarrativeTextBlock	The following information provides some indication of the risks of investing in the Fund by showing how the Fund’s performance has varied over time. Class T Shares (formerly named Class J Shares) of the Fund commenced operations with the Fund’s inception. Class A Shares, Class C Shares, Class S Shares, Class I Shares, and Class R Shares of the Fund commenced operations on July 6, 2009. Class N Shares of the Fund commenced operations on May 31, 2012. The performance shown for Class T Shares for periods following April 21, 2003, reflects the fees and expenses of Class T Shares in effect during the periods shown, net of any applicable fee and expense limitations or waivers. For the periods prior to April 21, 2003, the performance shown for Class T Shares reflects the historical performance of Berger Mid Cap Value Fund – Investor Shares (as a result of a prior reorganization of Berger Mid Cap Value Fund – Investor Shares into the Fund’s former Class J Shares). The performance shown for Class A Shares, Class C Shares, Class S Shares, and Class R Shares reflects the performance of the Fund’s Class J Shares (formerly named Investor Shares) from April 21, 2003 to July 6, 2009, calculated using the fees and expenses of each respective share class, without the effect of any fee and expense limitations or waivers. For periods prior to April 21, 2003, the performance shown for Class A Shares, Class C Shares, Class S Shares, and Class R Shares reflects the historical performance of Berger Mid Cap Value Fund – Investor Shares (as a result of a prior reorganization of Berger Mid Cap Value Fund – Investor Shares into the Fund’s former Class J Shares), calculated using the fees and expenses of each respective share class, without the effect of any fee and expense limitations or waivers. The performance shown for Class I Shares reflects the performance of the Fund’s Class J Shares (formerly named Investor Shares) from April 21, 2003 to July 6, 2009, calculated using the fees and expenses of Class J Shares, net of any applicable fee and expense limitations or waivers. For the periods prior to April 21, 2003, the performance shown for Class I Shares reflects the historical performance of Berger Mid Cap Value Fund – Investor Shares (as a result of a prior reorganization of Berger Mid Cap Value Fund – Investor Shares into the Fund’s former Class J Shares), calculated using the fees and expenses of Class J Shares, net of any applicable fee and expense limitations or waivers. The performance shown for Class N Shares reflects the performance of the Fund’s Class T Shares from July 6, 2009 to May 31, 2012, calculated using the fees and expenses of Class T Shares, net of any applicable fee and expense limitations or waivers. For the period from April 21, 2003 to July 6, 2009, the performance shown for Class N Shares reflects the performance of the Fund’s Class J Shares (formerly named Investor Shares), calculated using the fees and expenses of Class J Shares, net of any applicable fee and expense limitations or waivers. For the periods prior to April 21, 2003, the performance shown for Class N Shares reflects the historical performance of Berger Mid Cap Value Fund – Investor Shares (as a result of a prior reorganization of Berger Mid Cap Value Fund – Investor Shares into the Fund’s former Class J Shares), calculated using the fees and expenses of Class J Shares, net of any applicable fee and expense limitations or waivers. If Class A Shares, Class C Shares, Class S Shares, Class I Shares, and Class R Shares of the Fund had been available during periods prior to July 6, 2009, or Class N Shares of the Fund had been available during periods prior to May 31, 2012, the performance shown for each respective share class may have been different. The performance shown for periods following the Fund’s commencement of Class A Shares, Class C Shares, Class S Shares, Class I Shares, Class N Shares, and Class R Shares reflects the fees and expenses of each respective share class, net of any applicable fee and expense limitations or waivers. The bar chart depicts the change in performance from year to year during the periods indicated. The bar chart figures do not include any applicable sales charges that an investor may pay when they buy or sell Class A Shares or Class C Shares of the Fund. If sales charges were included, the returns would be lower. The table compares the Fund’s average annual returns for the periods indicated to a broad-based securities market index. The index is not actively managed and is not available for direct investment. All figures assume reinvestment of dividends and distributions. For certain periods, the Fund’s performance reflects the effect of expense waivers. Without the effect of these expense waivers, the performance shown would have been lower. The Fund’s past performance (before and after taxes) does not necessarily indicate how it will perform in the future. Updated performance information is available at janus.com/advisor/mutual-funds or by calling 1-877-335-2687.
Performance Information Illustrates Variability of Returns [Text]	rr_PerformanceInformationIllustratesVariabilityOfReturns	The following information provides some indication of the risks of investing in the Fund by showing how the Fund’s performance has varied over time. The bar chart depicts the change in performance from year to year during the periods indicated.
Performance Additional Market Index [Text]	rr_PerformanceAdditionalMarketIndex	The table compares the Fund’s average annual returns for the periods indicated to a broad-based securities market index. The index is not actively managed and is not available for direct investment. All figures assume reinvestment of dividends and distributions.
Performance Availability Phone [Text]	rr_PerformanceAvailabilityPhone	1-877-335-2687
Performance Availability Website Address [Text]	rr_PerformanceAvailabilityWebSiteAddress	janus.com/advisor/mutual-funds
Performance Past Does Not Indicate Future [Text]	rr_PerformancePastDoesNotIndicateFuture	The Fund’s past performance (before and after taxes) does not necessarily indicate how it will perform in the future.
Bar Chart [Heading]	rr_BarChartHeading	Annual Total Returns for Class T Shares (calendar year-end)
Bar Chart Does Not Reflect Sales Loads [Text]	rr_BarChartDoesNotReflectSalesLoads	The bar chart figures do not include any applicable sales charges that an investor may pay when they buy or sell Class A Shares or Class C Shares of the Fund. If sales charges were included, the returns would be lower.
Bar Chart Closing [Text Block]	rr_BarChartClosingTextBlock	Best Quarter:  Second Quarter 2003  17.17%          Worst Quarter:  Fourth Quarter 2008  −19.63%
Year to Date Return, Label	rr_YearToDateReturnLabel	The Fund’s year-to-date return as of the calendar quarter ended September 30, 2013 was 17.43%.
Performance Table Heading	rr_PerformanceTableHeading	Average Annual Total Returns (periods ended 12/31/12)
Performance Table Uses Highest Federal Rate	rr_PerformanceTableUsesHighestFederalRate	After-tax returns are calculated using the historically highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes.
Performance Table Not Relevant to Tax Deferred	rr_PerformanceTableNotRelevantToTaxDeferred	Actual after-tax returns depend on your individual tax situation and may differ from those shown in the preceding table. The after-tax return information shown above does not apply to Fund shares held through a tax-deferred account, such as a 401(k) plan or an IRA.
Performance Table One Class of after Tax Shown [Text]	rr_PerformanceTableOneClassOfAfterTaxShown	After-tax returns are only shown for Class T Shares of the Fund. After-tax returns for the other classes of Shares will vary from those shown for Class T Shares due to varying sales charges (as applicable), fees, and expenses among the classes.
Performance Table Explanation after Tax Higher	rr_PerformanceTableExplanationAfterTaxHigher	If the Fund incurs a loss, which generates a tax benefit, the Return After Taxes on Distributions and Sale of Fund Shares may exceed the Fund's other return figures.
Performance Table Narrative	rr_PerformanceTableNarrativeTextBlock	The Russell Midcap® Value Index measures the performance of those Russell Midcap® companies with lower price-to-book ratios and lower forecasted growth values. The stocks are also members of the Russell 1000® Value Index. This index is used to calculate the performance fee adjustment. After-tax returns are calculated using distributions for the Fund's Class T Shares (formerly named Class J Shares) for the periods following April 21, 2003; and for Berger Mid Cap Value Fund - Investor Shares for periods prior to April 21, 2003. If Class T Shares of the Fund had been available during the periods prior to April 21, 2003, distributions may have been different and thus, after-tax returns may have been different from those shown. After-tax returns are calculated using the historically highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes. Actual after-tax returns depend on your individual tax situation and may differ from those shown in the preceding table. The after-tax return information shown above does not apply to Fund shares held through a tax-deferred account, such as a 401(k) plan or an IRA. After-tax returns are only shown for Class T Shares of the Fund. After-tax returns for the other classes of Shares will vary from those shown for Class T Shares due to varying sales charges (as applicable), fees, and expenses among the classes.
Performance Table Closing [Text Block]	rr_PerformanceTableClosingTextBlock	Updated performance information is available at janus.com/advisor/mutual-funds or by calling 1-877-335-2687.
Perkins Mid Cap Value Fund | Class A, C, S, I, N, R, T Shares | Class A
Risk/Return:	rr_RiskReturnAbstract
Shareholder Fees Column [Text]	rr_ShareholderFeesColumnName	Class A
Maximum Sales Charge (load) Imposed on Purchases (as a percentage of offering price)	rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice	5.75%
Maximum Deferred Sales Charge (load) (as a percentage of the lower of original purchase price or redemption proceeds)	rr_MaximumDeferredSalesChargeOverOther	none
Operating Expenses Column [Text]	rr_OperatingExpensesColumnName	Class A
Management Fees (may adjust up or down)	rr_ManagementFeesOverAssets	0.48%
Distribution/Service (12b-1) Fees	rr_DistributionAndService12b1FeesOverAssets	0.25%
Other Expenses	rr_OtherExpensesOverAssets	0.27%
Total Annual Fund Operating Expenses	rr_ExpensesOverAssets	1.00%
Expense Example, By Year, Column [Text]	rr_ExpenseExampleByYearColumnName	Class A Shares
1 Year	rr_ExpenseExampleYear01	671
3 Years	rr_ExpenseExampleYear03	875
5 Years	rr_ExpenseExampleYear05	1,096
10 Years	rr_ExpenseExampleYear10	1,729
Expense Example, No Redemption, By Year, Column [Text]	rr_ExpenseExampleNoRedemptionByYearColumnName	Class A Shares
1 Year	rr_ExpenseExampleNoRedemptionYear01	671
3 Years	rr_ExpenseExampleNoRedemptionYear03	875
5 Years	rr_ExpenseExampleNoRedemptionYear05	1,096
10 Years	rr_ExpenseExampleNoRedemptionYear10	1,729
Perkins Mid Cap Value Fund | Class A, C, S, I, N, R, T Shares | Class C
Risk/Return:	rr_RiskReturnAbstract
Shareholder Fees Column [Text]	rr_ShareholderFeesColumnName	Class C
Maximum Sales Charge (load) Imposed on Purchases (as a percentage of offering price)	rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice	none
Maximum Deferred Sales Charge (load) (as a percentage of the lower of original purchase price or redemption proceeds)	rr_MaximumDeferredSalesChargeOverOther	1.00%
Operating Expenses Column [Text]	rr_OperatingExpensesColumnName	Class C
Management Fees (may adjust up or down)	rr_ManagementFeesOverAssets	0.48%
Distribution/Service (12b-1) Fees	rr_DistributionAndService12b1FeesOverAssets	1.00%
Other Expenses	rr_OtherExpensesOverAssets	0.24%
Total Annual Fund Operating Expenses	rr_ExpensesOverAssets	1.72%
Expense Example, By Year, Column [Text]	rr_ExpenseExampleByYearColumnName	Class C Shares
1 Year	rr_ExpenseExampleYear01	275
3 Years	rr_ExpenseExampleYear03	542
5 Years	rr_ExpenseExampleYear05	933
10 Years	rr_ExpenseExampleYear10	2,030
Expense Example, No Redemption, By Year, Column [Text]	rr_ExpenseExampleNoRedemptionByYearColumnName	Class C Shares
1 Year	rr_ExpenseExampleNoRedemptionYear01	175
3 Years	rr_ExpenseExampleNoRedemptionYear03	542
5 Years	rr_ExpenseExampleNoRedemptionYear05	933
10 Years	rr_ExpenseExampleNoRedemptionYear10	2,030
Perkins Mid Cap Value Fund | Class A, C, S, I, N, R, T Shares | Class S
Risk/Return:	rr_RiskReturnAbstract
Shareholder Fees Column [Text]	rr_ShareholderFeesColumnName	Class S
Maximum Sales Charge (load) Imposed on Purchases (as a percentage of offering price)	rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice	none
Maximum Deferred Sales Charge (load) (as a percentage of the lower of original purchase price or redemption proceeds)	rr_MaximumDeferredSalesChargeOverOther	none
Operating Expenses Column [Text]	rr_OperatingExpensesColumnName	Class S
Management Fees (may adjust up or down)	rr_ManagementFeesOverAssets	0.48%
Distribution/Service (12b-1) Fees	rr_DistributionAndService12b1FeesOverAssets	0.25%
Other Expenses	rr_OtherExpensesOverAssets	0.29%
Total Annual Fund Operating Expenses	rr_ExpensesOverAssets	1.02%
Expense Example, By Year, Column [Text]	rr_ExpenseExampleByYearColumnName	Class S Shares
1 Year	rr_ExpenseExampleYear01	104
3 Years	rr_ExpenseExampleYear03	325
5 Years	rr_ExpenseExampleYear05	563
10 Years	rr_ExpenseExampleYear10	1,248
Expense Example, No Redemption, By Year, Column [Text]	rr_ExpenseExampleNoRedemptionByYearColumnName	Class S Shares
1 Year	rr_ExpenseExampleNoRedemptionYear01	104
3 Years	rr_ExpenseExampleNoRedemptionYear03	325
5 Years	rr_ExpenseExampleNoRedemptionYear05	563
10 Years	rr_ExpenseExampleNoRedemptionYear10	1,248
Perkins Mid Cap Value Fund | Class A, C, S, I, N, R, T Shares | Class I
Risk/Return:	rr_RiskReturnAbstract
Shareholder Fees Column [Text]	rr_ShareholderFeesColumnName	Class I
Maximum Sales Charge (load) Imposed on Purchases (as a percentage of offering price)	rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice	none
Maximum Deferred Sales Charge (load) (as a percentage of the lower of original purchase price or redemption proceeds)	rr_MaximumDeferredSalesChargeOverOther	none
Operating Expenses Column [Text]	rr_OperatingExpensesColumnName	Class I
Management Fees (may adjust up or down)	rr_ManagementFeesOverAssets	0.48%
Distribution/Service (12b-1) Fees	rr_DistributionAndService12b1FeesOverAssets	none
Other Expenses	rr_OtherExpensesOverAssets	0.15%
Total Annual Fund Operating Expenses	rr_ExpensesOverAssets	0.63%
Expense Example, By Year, Column [Text]	rr_ExpenseExampleByYearColumnName	Class I Shares
1 Year	rr_ExpenseExampleYear01	64
3 Years	rr_ExpenseExampleYear03	202
5 Years	rr_ExpenseExampleYear05	351
10 Years	rr_ExpenseExampleYear10	786
Expense Example, No Redemption, By Year, Column [Text]	rr_ExpenseExampleNoRedemptionByYearColumnName	Class I Shares
1 Year	rr_ExpenseExampleNoRedemptionYear01	64
3 Years	rr_ExpenseExampleNoRedemptionYear03	202
5 Years	rr_ExpenseExampleNoRedemptionYear05	351
10 Years	rr_ExpenseExampleNoRedemptionYear10	786
Perkins Mid Cap Value Fund | Class A, C, S, I, N, R, T Shares | Class N
Risk/Return:	rr_RiskReturnAbstract
Shareholder Fees Column [Text]	rr_ShareholderFeesColumnName	Class N
Maximum Sales Charge (load) Imposed on Purchases (as a percentage of offering price)	rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice	none
Maximum Deferred Sales Charge (load) (as a percentage of the lower of original purchase price or redemption proceeds)	rr_MaximumDeferredSalesChargeOverOther	none
Operating Expenses Column [Text]	rr_OperatingExpensesColumnName	Class N
Management Fees (may adjust up or down)	rr_ManagementFeesOverAssets	0.48%
Distribution/Service (12b-1) Fees	rr_DistributionAndService12b1FeesOverAssets	none
Other Expenses	rr_OtherExpensesOverAssets	0.04%
Total Annual Fund Operating Expenses	rr_ExpensesOverAssets	0.52%
Expense Example, By Year, Column [Text]	rr_ExpenseExampleByYearColumnName	Class N Shares
1 Year	rr_ExpenseExampleYear01	53
3 Years	rr_ExpenseExampleYear03	167
5 Years	rr_ExpenseExampleYear05	291
10 Years	rr_ExpenseExampleYear10	653
Expense Example, No Redemption, By Year, Column [Text]	rr_ExpenseExampleNoRedemptionByYearColumnName	Class N Shares
1 Year	rr_ExpenseExampleNoRedemptionYear01	53
3 Years	rr_ExpenseExampleNoRedemptionYear03	167
5 Years	rr_ExpenseExampleNoRedemptionYear05	291
10 Years	rr_ExpenseExampleNoRedemptionYear10	653
Perkins Mid Cap Value Fund | Class A, C, S, I, N, R, T Shares | Class R
Risk/Return:	rr_RiskReturnAbstract
Shareholder Fees Column [Text]	rr_ShareholderFeesColumnName	Class R
Maximum Sales Charge (load) Imposed on Purchases (as a percentage of offering price)	rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice	none
Maximum Deferred Sales Charge (load) (as a percentage of the lower of original purchase price or redemption proceeds)	rr_MaximumDeferredSalesChargeOverOther	none
Operating Expenses Column [Text]	rr_OperatingExpensesColumnName	Class R
Management Fees (may adjust up or down)	rr_ManagementFeesOverAssets	0.48%
Distribution/Service (12b-1) Fees	rr_DistributionAndService12b1FeesOverAssets	0.50%
Other Expenses	rr_OtherExpensesOverAssets	0.28%
Total Annual Fund Operating Expenses	rr_ExpensesOverAssets	1.26%
Expense Example, By Year, Column [Text]	rr_ExpenseExampleByYearColumnName	Class R Shares
1 Year	rr_ExpenseExampleYear01	128
3 Years	rr_ExpenseExampleYear03	400
5 Years	rr_ExpenseExampleYear05	692
10 Years	rr_ExpenseExampleYear10	1,523
Expense Example, No Redemption, By Year, Column [Text]	rr_ExpenseExampleNoRedemptionByYearColumnName	Class R Shares
1 Year	rr_ExpenseExampleNoRedemptionYear01	128
3 Years	rr_ExpenseExampleNoRedemptionYear03	400
5 Years	rr_ExpenseExampleNoRedemptionYear05	692
10 Years	rr_ExpenseExampleNoRedemptionYear10	1,523
Perkins Mid Cap Value Fund | Class A, C, S, I, N, R, T Shares | Class T
Risk/Return:	rr_RiskReturnAbstract
Shareholder Fees Column [Text]	rr_ShareholderFeesColumnName	Class T
Maximum Sales Charge (load) Imposed on Purchases (as a percentage of offering price)	rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice	none
Maximum Deferred Sales Charge (load) (as a percentage of the lower of original purchase price or redemption proceeds)	rr_MaximumDeferredSalesChargeOverOther	none
Operating Expenses Column [Text]	rr_OperatingExpensesColumnName	Class T
Management Fees (may adjust up or down)	rr_ManagementFeesOverAssets	0.48%
Distribution/Service (12b-1) Fees	rr_DistributionAndService12b1FeesOverAssets	none
Other Expenses	rr_OtherExpensesOverAssets	0.29%
Total Annual Fund Operating Expenses	rr_ExpensesOverAssets	0.77%
Expense Example, By Year, Column [Text]	rr_ExpenseExampleByYearColumnName	Class T Shares
1 Year	rr_ExpenseExampleYear01	79
3 Years	rr_ExpenseExampleYear03	246
5 Years	rr_ExpenseExampleYear05	428
10 Years	rr_ExpenseExampleYear10	954
Expense Example, No Redemption, By Year, Column [Text]	rr_ExpenseExampleNoRedemptionByYearColumnName	Class T Shares
1 Year	rr_ExpenseExampleNoRedemptionYear01	79
3 Years	rr_ExpenseExampleNoRedemptionYear03	246
5 Years	rr_ExpenseExampleNoRedemptionYear05	428
10 Years	rr_ExpenseExampleNoRedemptionYear10	$ 954
2003	rr_AnnualReturn2003	39.33%
2004	rr_AnnualReturn2004	18.36%
2005	rr_AnnualReturn2005	10.36%
2006	rr_AnnualReturn2006	15.25%
2007	rr_AnnualReturn2007	7.43%
2008	rr_AnnualReturn2008	(27.33%)
2009	rr_AnnualReturn2009	30.37%
2010	rr_AnnualReturn2010	14.81%
2011	rr_AnnualReturn2011	(2.55%)
2012	rr_AnnualReturn2012	10.32%
Bar Chart, Year to Date Return, Date	rr_BarChartYearToDateReturnDate	Sep. 30, 2013
Bar Chart, Year to Date Return	rr_BarChartYearToDateReturn	17.43%
Highest Quarterly Return, Label	rr_HighestQuarterlyReturnLabel	Best Quarter:
Highest Quarterly Return, Date	rr_BarChartHighestQuarterlyReturnDate	Jun. 30, 2003
Highest Quarterly Return	rr_BarChartHighestQuarterlyReturn	17.17%
Lowest Quarterly Return, Label	rr_LowestQuarterlyReturnLabel	Worst Quarter:
Lowest Quarterly Return, Date	rr_BarChartLowestQuarterlyReturnDate	Dec. 31, 2008
Lowest Quarterly Return	rr_BarChartLowestQuarterlyReturn	(19.63%)
Perkins Mid Cap Value Fund | Class A, C, S, I, N, R, T Shares | Return Before Taxes | Class A
Risk/Return:	rr_RiskReturnAbstract
Column	rr_AverageAnnualReturnColumnName	Class A Shares
Label	rr_AverageAnnualReturnLabel	Return Before Taxes	[1]
1 Year	rr_AverageAnnualReturnYear01	3.75%
5 Years	rr_AverageAnnualReturnYear05	1.77%
10 Years	rr_AverageAnnualReturnYear10	9.31%
Since Inception of Predecessor Fund	rr_AverageAnnualReturnSinceInception	11.05%
Inception Date	rr_AverageAnnualReturnInceptionDate	Aug. 12, 1998
Perkins Mid Cap Value Fund | Class A, C, S, I, N, R, T Shares | Return Before Taxes | Class C
Risk/Return:	rr_RiskReturnAbstract
Column	rr_AverageAnnualReturnColumnName	Class C Shares
Label	rr_AverageAnnualReturnLabel	Return Before Taxes	[2]
1 Year	rr_AverageAnnualReturnYear01	8.20%
5 Years	rr_AverageAnnualReturnYear05	2.21%
10 Years	rr_AverageAnnualReturnYear10	9.17%
Since Inception of Predecessor Fund	rr_AverageAnnualReturnSinceInception	10.79%
Inception Date	rr_AverageAnnualReturnInceptionDate	Aug. 12, 1998
Perkins Mid Cap Value Fund | Class A, C, S, I, N, R, T Shares | Return Before Taxes | Class S
Risk/Return:	rr_RiskReturnAbstract
Column	rr_AverageAnnualReturnColumnName	Class S Shares
Label	rr_AverageAnnualReturnLabel	Return Before Taxes
1 Year	rr_AverageAnnualReturnYear01	9.99%
5 Years	rr_AverageAnnualReturnYear05	2.89%
10 Years	rr_AverageAnnualReturnYear10	9.84%
Since Inception of Predecessor Fund	rr_AverageAnnualReturnSinceInception	11.41%
Inception Date	rr_AverageAnnualReturnInceptionDate	Aug. 12, 1998
Perkins Mid Cap Value Fund | Class A, C, S, I, N, R, T Shares | Return Before Taxes | Class I
Risk/Return:	rr_RiskReturnAbstract
Column	rr_AverageAnnualReturnColumnName	Class I Shares
Label	rr_AverageAnnualReturnLabel	Return Before Taxes
1 Year	rr_AverageAnnualReturnYear01	10.41%
5 Years	rr_AverageAnnualReturnYear05	3.18%
10 Years	rr_AverageAnnualReturnYear10	10.17%
Since Inception of Predecessor Fund	rr_AverageAnnualReturnSinceInception	11.66%
Inception Date	rr_AverageAnnualReturnInceptionDate	Aug. 12, 1998
Perkins Mid Cap Value Fund | Class A, C, S, I, N, R, T Shares | Return Before Taxes | Class N
Risk/Return:	rr_RiskReturnAbstract
Column	rr_AverageAnnualReturnColumnName	Class N Shares
Label	rr_AverageAnnualReturnLabel	Return Before Taxes
1 Year	rr_AverageAnnualReturnYear01	10.32%
5 Years	rr_AverageAnnualReturnYear05	3.18%
10 Years	rr_AverageAnnualReturnYear10	10.17%
Since Inception of Predecessor Fund	rr_AverageAnnualReturnSinceInception	11.66%
Inception Date	rr_AverageAnnualReturnInceptionDate	Aug. 12, 1998
Perkins Mid Cap Value Fund | Class A, C, S, I, N, R, T Shares | Return Before Taxes | Class R
Risk/Return:	rr_RiskReturnAbstract
Column	rr_AverageAnnualReturnColumnName	Class R Shares
Label	rr_AverageAnnualReturnLabel	Return Before Taxes
1 Year	rr_AverageAnnualReturnYear01	9.72%
5 Years	rr_AverageAnnualReturnYear05	2.62%
10 Years	rr_AverageAnnualReturnYear10	9.57%
Since Inception of Predecessor Fund	rr_AverageAnnualReturnSinceInception	11.18%
Inception Date	rr_AverageAnnualReturnInceptionDate	Aug. 12, 1998
Perkins Mid Cap Value Fund | Class A, C, S, I, N, R, T Shares | Return Before Taxes | Class T
Risk/Return:	rr_RiskReturnAbstract
Column	rr_AverageAnnualReturnColumnName	Class T Shares
Label	rr_AverageAnnualReturnLabel	Return Before Taxes
1 Year	rr_AverageAnnualReturnYear01	10.32%
5 Years	rr_AverageAnnualReturnYear05	3.18%
10 Years	rr_AverageAnnualReturnYear10	10.17%
Since Inception of Predecessor Fund	rr_AverageAnnualReturnSinceInception	11.66%
Inception Date	rr_AverageAnnualReturnInceptionDate	Aug. 12, 1998
Perkins Mid Cap Value Fund | Class A, C, S, I, N, R, T Shares | Return After Taxes on Distributions | Class T
Risk/Return:	rr_RiskReturnAbstract
Column	rr_AverageAnnualReturnColumnName	Class T Shares
Label	rr_AverageAnnualReturnLabel	Return After Taxes on Distributions
1 Year	rr_AverageAnnualReturnYear01	9.63%
5 Years	rr_AverageAnnualReturnYear05	2.53%
10 Years	rr_AverageAnnualReturnYear10	8.99%
Since Inception of Predecessor Fund	rr_AverageAnnualReturnSinceInception	10.26%
Inception Date	rr_AverageAnnualReturnInceptionDate	Aug. 12, 1998
Perkins Mid Cap Value Fund | Class A, C, S, I, N, R, T Shares | Return After Taxes on Distributions and Sale of Fund Shares | Class T
Risk/Return:	rr_RiskReturnAbstract
Column	rr_AverageAnnualReturnColumnName	Class T Shares
Label	rr_AverageAnnualReturnLabel	Return After Taxes on Distributions and Sale of Fund Shares	[3]
1 Year	rr_AverageAnnualReturnYear01	7.65%
5 Years	rr_AverageAnnualReturnYear05	2.60%
10 Years	rr_AverageAnnualReturnYear10	8.67%
Since Inception of Predecessor Fund	rr_AverageAnnualReturnSinceInception	9.89%
Inception Date	rr_AverageAnnualReturnInceptionDate	Aug. 12, 1998
Perkins Mid Cap Value Fund | Class A, C, S, I, N, R, T Shares | Russell Midcap® Value Index (reflects no deduction for expenses, fees, or taxes)
Risk/Return:	rr_RiskReturnAbstract
Label	rr_AverageAnnualReturnLabel	Russell Midcap® Value Index
1 Year	rr_AverageAnnualReturnYear01	18.51%
5 Years	rr_AverageAnnualReturnYear05	3.79%
10 Years	rr_AverageAnnualReturnYear10	10.63%
Since Inception of Predecessor Fund	rr_AverageAnnualReturnSinceInception	8.42%
Inception Date	rr_AverageAnnualReturnInceptionDate	Aug. 12, 1998

[1] Calculated assuming maximum permitted sales loads.

[2] The one year return is calculated to include the contingent deferred sales charge.

[3] If the Fund incurs a loss, which generates a tax benefit, the Return After Taxes on Distributions and Sale of Fund Shares may exceed the Fund's other return figures.

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Perkins Large Cap Value Fund | Class A, C, S, I, N, T Shares

FUND SUMMARY

Perkins Large Cap Value Fund

INVESTMENT OBJECTIVE

Perkins Large Cap Value Fund seeks capital appreciation.

FEES AND EXPENSES OF THE FUND

This table describes the fees and expenses that you may pay if you buy and hold Shares of the Fund. Each share class has different expenses, but represents an investment in the same Fund.

For Class A Shares, you may qualify for sales charge discounts if you and your family invest, or agree to invest in the future, at least $50,000 in the Fund or in other Janus mutual funds. More information about these and other discounts, as well as eligibility requirements for each share class, is available from your financial professional and in the “Purchases” section on page 66 of the Fund’s Prospectus and in the “Purchases” section on page 70 of the Fund’s Statement of Additional Information.

SHAREHOLDER FEES
(fees paid directly from your investment)

Shareholder Fees Perkins Large Cap Value Fund Class A, C, S, I, N, T Shares	Class A	Class C	Class S	Class I	Class N	Class T
Shareholder Fees Column [Text]	Class A	Class C	Class S	Class I	Class N	Class T
Maximum Sales Charge (load) Imposed on Purchases (as a percentage of offering price)	5.75%	none	none	none	none	none
Maximum Deferred Sales Charge (load) (as a percentage of the lower of original purchase price or redemption proceeds)	none	1.00%	none	none	none	none

ANNUAL FUND OPERATING EXPENSES
(expenses that you pay each year as a percentage of the value of your investment)

Annual Fund Operating Expenses Perkins Large Cap Value Fund Class A, C, S, I, N, T Shares		Class A	Class C	Class S	Class I	Class N	Class T
Operating Expenses Column [Text]		Class A	Class C	Class S	Class I	Class N	Class T
Management Fees (may adjust up or down)		0.52%	0.52%	0.52%	0.52%	0.52%	0.52%
Distribution/Service (12b-1) Fees		0.25%	1.00%	0.25%	none	none	none
Other Expenses		0.38%	0.29%	0.42%	0.19%	0.16%	0.42%
Total Annual Fund Operating Expenses	[1]	1.15%	1.81%	1.19%	0.71%	0.68%	0.94%
Fee Waiver	[1]	0.07%	0.08%	0.06%	0.07%	0.05%	0.06%
Total Annual Fund Operating Expenses After Fee Waiver	[1]	1.08%	1.73%	1.13%	0.64%	0.63%	0.88%

EXAMPLE:

The following Example is based on expenses without waivers. The Example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds.

The Example assumes that you invest $10,000 in the Fund for the time periods indicated and reinvest all dividends and distributions. The Example also assumes that your investment has a 5% return each year and that the Fund’s operating expenses without waivers remain the same. Although your actual costs may be higher or lower, based on these assumptions your costs would be:

If Shares are redeemed:

Expense Example Perkins Large Cap Value Fund Class A, C, S, I, N, T Shares (USD $)	Expense Example, By Year, Column [Text]	1 Year	3 Years	5 Years	10 Years
Class A	Class A Shares	685	919	1,172	1,892
Class C	Class C Shares	284	569	980	2,127
Class S	Class S Shares	121	378	654	1,443
Class I	Class I Shares	73	227	395	883
Class N	Class N Shares	69	218	379	847
Class T	Class T Shares	96	300	520	1,155

If Shares are not redeemed:

Expense Example, No Redemption Perkins Large Cap Value Fund Class A, C, S, I, N, T Shares (USD $)	Expense Example, No Redemption, By Year, Column [Text]	1 Year	3 Years	5 Years	10 Years
Class A	Class A Shares	685	919	1,172	1,892
Class C	Class C Shares	184	569	980	2,127
Class S	Class S Shares	121	378	654	1,433
Class I	Class I Shares	73	227	395	883
Class N	Class N Shares	69	218	379	847
Class T	Class T Shares	96	300	520	1,155

Portfolio Turnover:

The Fund pays transaction costs, such as commissions, when it buys and sells securities (or “turns over” its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when Fund shares are held in a taxable account. These costs, which are not reflected in annual fund operating expenses or in the Example, affect the Fund’s performance. During the most recent fiscal year, the Fund’s portfolio turnover rate was 45% of the average value of its portfolio.

PRINCIPAL INVESTMENT STRATEGIES

The Fund pursues its investment objective by investing primarily in common stocks selected for their capital appreciation potential. The Fund primarily invests in the common stocks of large-sized companies whose stock prices the portfolio managers believe to be undervalued. The Fund invests, under normal circumstances, at least 80% of its net assets in equity securities of companies having, at the time of purchase, market capitalizations equal to or greater than the median market capitalization of companies included in the Russell 1000^® Value Index. The market capitalizations within the index will vary, but as of June 30, 2013, they ranged from approximately $487 million to $422.5 billion, and the median market capitalization was $5.9 billion. The Fund may also invest in foreign equity and debt securities, which may include investments in emerging markets. The Fund may invest, under normal circumstances, up to 20% of its net assets in securities of companies having market capitalizations outside of the aforementioned market capitalization ranges. In addition, when the portfolio managers believe that market conditions are unfavorable for investing, or when they are otherwise unable to locate attractive investment opportunities, the Fund may invest up to 20% of its net assets in exchange-traded funds ("ETFs"), including commodity-related ETFs, cash, or similar investments.

The Fund focuses on companies that have fallen out of favor with the market or that appear to be temporarily misunderstood by the investment community. The Fund's portfolio managers generally look for companies with:

• strong balance sheets and solid recurring free cash flows
• attractive relative and absolute valuation ratios or that have underperformed recently
• favorable reward to risk characteristics

The Fund may invest its assets in derivatives, which are instruments that have a value derived from, or directly linked to, an underlying asset, such as equity securities, fixed-income securities, commodities, currencies, interest rates, or market indices, as substitutes for securities in which the Fund invests. The Fund may invest in derivative instruments (by taking long and/or short positions) for different purposes, including hedging (to offset risks associated with an investment, currency exposure, or market conditions) and to earn income and enhance returns.

PRINCIPAL INVESTMENT RISKS

The biggest risk is that the Fund's returns will vary, and you could lose money. The Fund is designed for long-term investors seeking an equity portfolio, including common stocks. Common stocks tend to be more volatile than many other investment choices.

Value Investing Risk. Because different types of stocks tend to shift in and out of favor depending on market and economic conditions, "value" stocks may perform differently than other types of stocks and from the market as a whole, and can continue to be undervalued by the market for long periods of time. It is also possible that a value stock will never appreciate to the extent expected by the portfolio managers. When the Fund's investments in cash or similar investments increase due to a lack of favorable investment opportunities or other extraordinary factors, the Fund may not participate in market advances or declines to the same extent that it would if the Fund had been fully invested.

Market Risk. The value of the Fund's portfolio may decrease if the value of an individual company or security, or multiple companies or securities, in the portfolio decreases or if the portfolio managers' belief about a company's intrinsic worth is incorrect. Further, regardless of how well individual companies or securities perform, the value of the Fund's portfolio could also decrease if there are deteriorating economic or market conditions. It is important to understand that the value of your investment may fall, sometimes sharply, in response to changes in the market, and you could lose money.

Foreign Exposure Risk. The Fund may have exposure to foreign markets as a result of its investments in foreign securities, including investments in emerging markets, which can be more volatile than the U.S. markets. As a result, its returns and net asset value may be affected to a large degree by fluctuations in currency exchange rates or political or economic conditions in a particular country. In some foreign markets, there may not be protection against failure by other parties to complete transactions. It may not be possible for the Fund to repatriate capital, dividends, interest, and other income from a particular country or governmental entity. In addition, a market swing in one or more countries or regions where the Fund has invested a significant amount of its assets may have a greater effect on the Fund's performance than it would in a more geographically diversified portfolio. To the extent the Fund invests in foreign debt securities, such investments are sensitive to changes in interest rates. Additionally, investments in securities of foreign governments involve the risk that a foreign government may not be willing or able to pay interest or repay principal when due.

Eurozone Risk. A number of countries in the European Union ("EU") have experienced severe economic and financial difficulties. As a result, financial markets in the EU have been subject to extreme volatility and declines in asset values and liquidity. Responses to these financial problems by European governments, central banks, and others, including austerity measures and reforms, may not work, may result in social unrest, and may limit future growth and economic recovery or have other unintended consequences. Further defaults or restructurings by governments and others of their debt could have additional adverse effects on economies, financial markets, and asset valuations around the world. To the extent that the Fund has exposure to European markets or to transactions tied to the value of the euro, these events could negatively affect the value and liquidity of the Fund's investments.

Exchange-Traded Funds Risk. The Fund may invest in ETFs, which are typically open-end investment companies that are traded on a national securities exchange. ETFs typically incur fees, such as investment advisory fees and other operating expenses that are separate from those of the Fund, which will be indirectly paid by the Fund. As a result, the cost of investing in the Fund may be higher than the cost of investing directly in ETFs and may be higher than other mutual funds that invest directly in stocks and bonds. Further, the price movement of an ETF may fluctuate against the underlying securities or commodities it tracks and may result in a loss. Because the value of ETF shares depends on the demand in the market, the Fund may not be able to purchase or sell an ETF at the most optimal time, which could adversely affect the Fund's performance.

The ETFs in which the Fund invests are subject to specific risks, depending on the investment strategy of the ETF. In turn, the Fund will be subject to substantially the same risks as those associated with direct exposure to the securities or commodities held by the ETF. Because the Fund may invest in a broad range of ETFs, such risks may include, but are not limited to, leverage risk, foreign exposure risk, and commodities risk.

Derivatives Risk. Derivatives can be highly volatile and involve risks in addition to the risks of the underlying referenced securities. Gains or losses from a derivative investment can be substantially greater than the derivative's original cost, and can therefore involve leverage. Leverage may cause the Fund to be more volatile than if it had not used leverage. Derivatives can be less liquid than other types of investments and entail the risk that the counterparty will default on its payment obligations.

An investment in the Fund is not a bank deposit and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency.

PERFORMANCE INFORMATION

The following information provides some indication of the risks of investing in the Fund by showing how the Fund’s performance has varied over time. Class I Shares, Class A Shares, Class C Shares, and Class S Shares of the Fund commenced operations on July 6, 2009, after the reorganization of each corresponding class of shares of Janus Adviser Perkins Large Cap Value Fund (“JAD predecessor fund”) into each respective share class of the Fund. Class T Shares of the Fund commenced operations on July 6, 2009. Class N Shares of the Fund commenced operations on May 31, 2012.

• The performance shown for Class I Shares, Class A Shares, Class C Shares, and Class S Shares for periods prior to July 6, 2009, reflects the historical performance of the JAD predecessor fund’s Class I Shares, Class A Shares, Class C Shares, and Class S Shares prior to the reorganization, calculated using the fees and expenses of each respective share class of the JAD predecessor fund, net of any applicable fee and expense limitations or waivers.
• The performance shown for Class N Shares reflects the performance of the Fund’s Class I Shares from July 6, 2009 to May 31, 2012, calculated using the fees and expenses of Class I Shares, net of any applicable fee and expense limitations or waivers. The performance shown for Class N Shares for periods prior to July 6, 2009, reflects the historical performance of the JAD predecessor fund’s Class I Shares prior to the reorganization, calculated using the fees and expenses of Class I Shares of the JAD predecessor fund, net of any applicable fee and expense limitations or waivers.
• The performance shown for Class T Shares for periods prior to July 6, 2009, reflects the historical performance of the JAD predecessor fund’s Class I Shares prior to the reorganization, calculated using the fees and expenses of Class T Shares, without the effect of any fee and expense limitations or waivers.

If Class T Shares of the Fund had been available during periods prior to July 6, 2009, or Class N Shares of the Fund had been available during periods prior to May 31, 2012, the performance shown for each respective share class may have been different. The performance shown for periods following the Fund’s commencement of Class I Shares, Class A Shares, Class C Shares, Class S Shares, Class N Shares, and Class T Shares reflects the fees and expenses of each respective share class, net of any applicable fee and expense limitations or waivers.

The bar chart depicts the change in performance from year to year during the periods indicated. The bar chart figures do not include any applicable sales charges that an investor may pay when they buy or sell Class A Shares or Class C Shares of the Fund. If sales charges were included, the returns would be lower. The table compares the Fund’s average annual returns for the periods indicated to a broad-based securities market index. The index is not actively managed and is not available for direct investment. All figures assume reinvestment of dividends and distributions. For certain periods, the Fund’s performance reflects the effect of expense waivers. Without the effect of these expense waivers, the performance shown would have been lower.

The Fund’s past performance (before and after taxes) does not necessarily indicate how it will perform in the future. Updated performance information is available at janus.com/advisor/mutual-funds or by calling 1-877-335-2687.

Annual Total Returns for Class I Shares (calendar year-end)

Best Quarter:  Second Quarter 2009  15.40%          Worst Quarter:  Third Quarter 2011  −14.75%

The Fund’s year-to-date return as of the calendar quarter ended September 30, 2013 was 18.00%.

Average Annual Total Returns (periods ended 12/31/12)

Average Annual Total Returns Perkins Large Cap Value Fund Class A, C, S, I, N, T Shares	Column	Label		1 Year	Since Inception of Predecessor Fund	Inception Date
Class I Return Before Taxes	Class I Shares	Return Before Taxes		13.33%	12.26%	Dec. 31, 2008
Class I Return After Taxes on Distributions	Class I Shares	Return After Taxes on Distributions		12.76%	11.51%	Dec. 31, 2008
Class I Return After Taxes on Distributions and Sale of Fund Shares	Class I Shares	Return After Taxes on Distributions and Sale of Fund Shares		9.44%	10.45%	Dec. 31, 2008
Class A Return Before Taxes	Class A Shares	Return Before Taxes	[1]	6.45%	10.27%	Dec. 31, 2008
Class C Return Before Taxes	Class C Shares	Return Before Taxes	[2]	10.90%	11.05%	Dec. 31, 2008
Class S Return Before Taxes	Class S Shares	Return Before Taxes		12.93%	11.75%	Dec. 31, 2008
Class N Return Before Taxes	Class N Shares	Return Before Taxes		13.33%	12.26%	Dec. 31, 2008
Class T Return Before Taxes	Class T Shares	Return Before Taxes		13.08%	11.88%	Dec. 31, 2008
Russell 1000® Value Index (reflects no deduction for expenses, fees, or taxes)		Russell 1000® Value Index		17.51%	13.01%	Dec. 31, 2008

The Russell 1000^® Value Index measures the performance of those Russell 1000^® companies with lower price-to-book ratios and lower forecasted growth values. This index is used to calculate the performance fee adjustment.

After-tax returns are calculated using distributions for the Fund’s Class I Shares for periods following July 6, 2009; and for the JAD predecessor fund’s Class I Shares for periods prior to July 6, 2009. After-tax returns are calculated using the historically highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes. Actual after-tax returns depend on your individual tax situation and may differ from those shown in the preceding table. The after-tax return information shown above does not apply to Fund shares held through a tax-deferred account, such as a 401(k) plan or an IRA.

After-tax returns are only shown for Class I Shares of the Fund. After-tax returns for the other classes of Shares will vary from those shown for Class I Shares due to varying sales charges (as applicable), fees, and expenses among the classes.

[1] Janus Capital has contractually agreed to waive its investment advisory fee and/or reimburse Fund expenses to the extent that the Fund's total annual fund operating expenses (excluding any performance adjustments to management fees, the distribution and shareholder servicing fees– applicable to Class A Shares, Class C Shares, and Class S Shares; administrative services fees payable pursuant to the Transfer Agency Agreement; brokerage commissions; interest; dividends; taxes; acquired fund fees and expenses; and extraordinary expenses) exceed 0.75% until at least November 1, 2014. The contractual waiver may be terminated or modified prior to this date only at the discretion of the Board of Trustees.

[1] Calculated assuming maximum permitted sales loads.

[2] The one year return is calculated to include the contingent deferred sales charge.

XML

Label	Element	Value
Risk/Return:	rr_RiskReturnAbstract
Registrant Name	dei_EntityRegistrantName	JANUS INVESTMENT FUND
Prospectus Date	rr_ProspectusDate	Oct. 28, 2013
Janus High-Yield Fund | Class D Shares
Risk/Return:	rr_RiskReturnAbstract
Risk/Return [Heading]	rr_RiskReturnHeading	FUND SUMMARY Janus High-Yield Fund
Objective [Heading]	rr_ObjectiveHeading	INVESTMENT OBJECTIVES
Objective, Primary [Text Block]	rr_ObjectivePrimaryTextBlock	Janus High-Yield Fund seeks to obtain high current income.
Objective, Secondary [Text Block]	rr_ObjectiveSecondaryTextBlock	Capital appreciation is a secondary investment objective when consistent with its primary investment objective.
Expense [Heading]	rr_ExpenseHeading	FEES AND EXPENSES OF THE FUND
Expense Narrative [Text Block]	rr_ExpenseNarrativeTextBlock	This table describes the fees and expenses that you may pay if you buy and hold Shares of the Fund.
Operating Expenses Caption [Text]	rr_OperatingExpensesCaption	ANNUAL FUND OPERATING EXPENSES (expenses that you pay each year as a percentage of the value of your investment)
Portfolio Turnover [Heading]	rr_PortfolioTurnoverHeading	Portfolio Turnover:
Portfolio Turnover [Text Block]	rr_PortfolioTurnoverTextBlock	The Fund pays transaction costs, such as commissions, when it buys and sells securities (or “turns over” its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when Fund shares are held in a taxable account. These costs, which are not reflected in annual fund operating expenses or in the Example, affect the Fund’s performance. During the most recent fiscal year, the Fund’s portfolio turnover rate was 93% of the average value of its portfolio.
Portfolio Turnover, Rate	rr_PortfolioTurnoverRate	93.00%
Expense Example [Heading]	rr_ExpenseExampleHeading	EXAMPLE:
Expense Example by Year [Heading]	rr_ExpenseExampleByYearHeading	The Example assumes that you invest $10,000 in the Fund for the time periods indicated, reinvest all dividends and distributions, and then redeem all of your Shares at the end of each period. The Example also assumes that your investment has a 5% return each year and that the Fund’s operating expenses remain the same. Although your actual costs may be higher or lower, based on these assumptions your costs would be:
Expense Example Narrative [Text Block]	rr_ExpenseExampleNarrativeTextBlock	The Example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds.
Strategy [Heading]	rr_StrategyHeading	PRINCIPAL INVESTMENT STRATEGIES
Strategy Narrative [Text Block]	rr_StrategyNarrativeTextBlock	The Fund pursues its investment objectives by investing, under normal circumstances, at least 80% of its net assets in high-yield/high-risk securities rated below investment grade. Securities rated below investment grade may include their unrated equivalents or other high-yielding securities the portfolio managers believe offer attractive risk/return characteristics. The Fund may at times invest all of its assets in such securities. The Fund may also invest in bank loans, money market instruments, and foreign debt securities (which may include investments in emerging markets). Due to the nature of securities in which the Fund invests, it may have relatively high portfolio turnover compared to other funds. In addition, the Fund may invest its assets in derivatives, which are instruments that have a value derived from, or directly linked to, an underlying asset, such as equity securities, fixed-income securities, commodities, currencies, interest rates, or market indices. In particular, the Fund may use interest rate futures to manage portfolio risk. The Fund’s exposure to derivatives will vary. For purposes of meeting its 80% investment policy, the Fund may include derivatives that have characteristics similar to the securities in which the Fund may directly invest. In addition to considering economic factors such as the effect of interest rates on the Fund’s investments, the portfolio managers apply a “bottom up” approach in choosing investments. This means that the portfolio managers look at income-producing securities one at a time to determine if a security is an attractive investment opportunity and if it is consistent with the Fund’s investment policies. The Fund may lend portfolio securities on a short-term or long-term basis, in an amount equal to up to 1/3 of its total assets as determined at the time of the loan origination.
Risk [Heading]	rr_RiskHeading	PRINCIPAL INVESTMENT RISKS
Risk Narrative [Text Block]	rr_RiskNarrativeTextBlock	Although the Fund may be less volatile than funds that invest most of their assets in common stocks, the Fund’s returns and yields will vary, and you could lose money. Fixed-Income Securities Risk. The Fund invests in a variety of fixed-income securities. Typically, the values of fixed-income securities change inversely with prevailing interest rates. Therefore, a fundamental risk of fixed-income securities is interest rate risk, which is the risk that the value of such securities will generally decline as prevailing interest rates rise, which may cause the Fund’s net asset value to likewise decrease. How specific fixed-income securities may react to changes in interest rates will depend on the specific characteristics of each security. Fixed-income securities are also subject to credit risk, prepayment risk, valuation risk, and liquidity risk. Credit risk is the risk that the credit strength of an issuer of a fixed-income security will weaken and/or that the issuer will be unable to make timely principal and interest payments and that the security may go into default. Prepayment risk is the risk that during periods of falling interest rates, certain fixed-income securities with higher interest rates, such as mortgage- and asset-backed securities, may be prepaid by their issuers thereby reducing the amount of interest payments. Valuation risk is the risk that one or more of the fixed-income securities in which the Fund invests are priced differently than the value realized upon such security’s sale. In times of market instability, valuation may be more difficult. Liquidity risk is the risk that fixed-income securities may be difficult or impossible to sell at the time that the portfolio managers would like or at the price the portfolio managers believe the security is currently worth. High-Yield/High-Risk Bond Risk. The Fund may invest without limit in higher-yielding/higher-risk bonds, also known as “junk” bonds. High-yield/high-risk bonds may be more sensitive than other types of bonds to economic changes, political changes, or adverse developments specific to the company that issued the bond, which may adversely affect their value. Bank Loan Risk. Bank loans are obligations of companies or other entities entered into in connection with recapitalizations, acquisitions, and refinancings. The Fund’s investments in bank loans are generally acquired as a participation interest in, or assignment of, loans originated by a lender or other financial institution. These investments may include institutionally-traded floating and fixed-rate debt securities. Participation interests and assignments involve credit, interest rate, and liquidity risk. In addition, the bank loans underlying these securities often involve borrowers with low credit ratings whose financial conditions are troubled or uncertain, including companies that are highly leveraged or in bankruptcy proceedings. Foreign Exposure Risk. The Fund may have exposure to foreign markets as a result of its investments in foreign securities, including investments in emerging markets, which can be more volatile than the U.S. markets. As a result, its returns and net asset value may be affected to a large degree by fluctuations in currency exchange rates or political or economic conditions in a particular country. In some foreign markets, there may not be protection against failure by other parties to complete transactions. It may not be possible for the Fund to repatriate capital, dividends, interest, and other income from a particular country or governmental entity. In addition, a market swing in one or more countries or regions where the Fund has invested a significant amount of its assets may have a greater effect on the Fund’s performance than it would in a more geographically diversified portfolio. To the extent the Fund invests in foreign debt securities, such investments are sensitive to changes in interest rates. Additionally, investments in securities of foreign governments involve the risk that a foreign government may not be willing or able to pay interest or repay principal when due. The Fund’s investments in emerging market countries may involve risks greater than, or in addition to, the risks of investing in more developed countries. Portfolio Turnover Risk. Increased portfolio turnover may result in higher costs, which may have a negative effect on the Fund’s performance. In addition, higher portfolio turnover may result in the acceleration of capital gains and the recognition of greater levels of short-term capital gains, which are taxed at ordinary federal income tax rates when distributed to shareholders. Derivatives Risk. Derivatives can be highly volatile and involve risks in addition to the risks of the underlying referenced securities. Gains or losses from a derivative investment can be substantially greater than the derivative’s original cost, and can therefore involve leverage. Leverage may cause the Fund to be more volatile than if it had not used leverage. Derivatives can be less liquid than other types of investments and entail the risk that the counterparty will default on its payment obligations. Securities Lending Risk. The Fund may seek to earn additional income through lending its securities to certain qualified broker-dealers and institutions. There is the risk that when portfolio securities are lent, the securities may not be returned on a timely basis, and the Fund may experience delays and costs in recovering the security or gaining access to the collateral provided to the Fund to collateralize the loan. If the Fund is unable to recover a security on loan, the Fund may use the collateral to purchase replacement securities in the market. There is a risk that the value of the collateral could decrease below the cost of the replacement security by the time the replacement investment is made, resulting in a loss to the Fund. An investment in the Fund is not a bank deposit and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency.
Risk Lose Money [Text]	rr_RiskLoseMoney	Although the Fund may be less volatile than funds that invest most of their assets in common stocks, the Fund’s returns and yields will vary, and you could lose money.
Risk Not Insured Depository Institution [Text]	rr_RiskNotInsuredDepositoryInstitution	An investment in the Fund is not a bank deposit and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency.
Bar Chart and Performance Table [Heading]	rr_BarChartAndPerformanceTableHeading	PERFORMANCE INFORMATION
Performance Narrative [Text Block]	rr_PerformanceNarrativeTextBlock	The following information provides some indication of the risks of investing in the Fund by showing how the Fund’s performance has varied over time. Class D Shares of the Fund commenced operations on February 16, 2010, as a result of the restructuring of Class J Shares, the predecessor share class. The performance shown for Class D Shares for periods prior to February 16, 2010, reflects the performance of the Fund’s former Class J Shares, calculated using the fees and expenses in effect during the periods shown, net of any applicable fee and expense limitations or waivers. If Class D Shares of the Fund had been available during periods prior to February 16, 2010, the performance shown may have been different. The performance shown for periods following the Fund’s commencement of Class D Shares reflects the fees and expenses of Class D Shares, net of any applicable fee and expense limitations or waivers. The bar chart depicts the change in performance from year to year during the periods indicated. The table compares the Fund’s average annual returns for the periods indicated to a broad-based securities market index. The index is not actively managed and is not available for direct investment. All figures assume reinvestment of dividends and distributions. For certain periods, the Fund’s performance reflects the effect of expense waivers. Without the effect of these expense waivers, the performance shown would have been lower. The Fund’s past performance (before and after taxes) does not necessarily indicate how it will perform in the future. Updated performance information is available at janus.com/allfunds or by calling 1-800-525-3713.
Performance Information Illustrates Variability of Returns [Text]	rr_PerformanceInformationIllustratesVariabilityOfReturns	The following information provides some indication of the risks of investing in the Fund by showing how the Fund’s performance has varied over time. The bar chart depicts the change in performance from year to year during the periods indicated.
Performance Additional Market Index [Text]	rr_PerformanceAdditionalMarketIndex	The table compares the Fund’s average annual returns for the periods indicated to a broad-based securities market index. The index is not actively managed and is not available for direct investment. All figures assume reinvestment of dividends and distributions.
Performance Availability Phone [Text]	rr_PerformanceAvailabilityPhone	1-800-525-3713
Performance Availability Website Address [Text]	rr_PerformanceAvailabilityWebSiteAddress	janus.com/allfunds
Performance Past Does Not Indicate Future [Text]	rr_PerformancePastDoesNotIndicateFuture	The Fund’s past performance (before and after taxes) does not necessarily indicate how it will perform in the future.
Bar Chart [Heading]	rr_BarChartHeading	Annual Total Returns for Class D Shares (calendar year-end)
Bar Chart Closing [Text Block]	rr_BarChartClosingTextBlock	Best Quarter:  Second Quarter 2009  14.93%          Worst Quarter:  Fourth Quarter 2008  −12.96%
Year to Date Return, Label	rr_YearToDateReturnLabel	The Fund’s year-to-date return as of the calendar quarter ended September 30, 2013 was 3.61%.
Performance Table Heading	rr_PerformanceTableHeading	Average Annual Total Returns (periods ended 12/31/12)
Performance Table Uses Highest Federal Rate	rr_PerformanceTableUsesHighestFederalRate	After-tax returns are calculated using the historically highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes.
Performance Table Not Relevant to Tax Deferred	rr_PerformanceTableNotRelevantToTaxDeferred	Actual after-tax returns depend on your individual tax situation and may differ from those shown in the preceding table. The after-tax return information shown above does not apply to Fund shares held through a tax-deferred account, such as a 401(k) plan or an IRA.
Performance Table Explanation after Tax Higher	rr_PerformanceTableExplanationAfterTaxHigher	If the Fund incurs a loss, which generates a tax benefit, the Return After Taxes on Distributions and Sale of Fund Shares may exceed the Fund’s other return figures.
Performance Table Narrative	rr_PerformanceTableNarrativeTextBlock	After-tax returns are calculated using distributions for the Fund’s Class D Shares for the periods following February 16, 2010; and for the Fund’s Class J Shares, the predecessor share class, for the periods prior to February 16, 2010. If Class D Shares of the Fund had been available during these earlier periods, distributions may have been different and thus, after-tax returns may have been different from those shown. After-tax returns are calculated using the historically highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes. Actual after-tax returns depend on your individual tax situation and may differ from those shown in the preceding table. The after-tax return information shown above does not apply to Fund shares held through a tax-deferred account, such as a 401(k) plan or an IRA.
Performance Table Closing [Text Block]	rr_PerformanceTableClosingTextBlock	Updated performance information is available at janus.com/allfunds or by calling 1-800-525-3713.
Janus High-Yield Fund | Class D Shares | Class D
Risk/Return:	rr_RiskReturnAbstract
Operating Expenses Column [Text]	rr_OperatingExpensesColumnName	Class D
Management Fees	rr_ManagementFeesOverAssets	0.56%
Other Expenses	rr_OtherExpensesOverAssets	0.21%
Total Annual Fund Operating Expenses	rr_ExpensesOverAssets	0.77%
Expense Example, By Year, Column [Text]	rr_ExpenseExampleByYearColumnName	Class D Shares
1 Year	rr_ExpenseExampleYear01	$ 79
3 Years	rr_ExpenseExampleYear03	246
5 Years	rr_ExpenseExampleYear05	428
10 Years	rr_ExpenseExampleYear10	$ 954
2003	rr_AnnualReturn2003	16.04%
2004	rr_AnnualReturn2004	9.42%
2005	rr_AnnualReturn2005	2.77%
2006	rr_AnnualReturn2006	11.10%
2007	rr_AnnualReturn2007	1.35%
2008	rr_AnnualReturn2008	(19.32%)
2009	rr_AnnualReturn2009	40.86%
2010	rr_AnnualReturn2010	15.80%
2011	rr_AnnualReturn2011	3.32%
2012	rr_AnnualReturn2012	14.40%
Bar Chart, Year to Date Return, Date	rr_BarChartYearToDateReturnDate	Sep. 30, 2013
Bar Chart, Year to Date Return	rr_BarChartYearToDateReturn	3.61%
Highest Quarterly Return, Label	rr_HighestQuarterlyReturnLabel	Best Quarter:
Highest Quarterly Return, Date	rr_BarChartHighestQuarterlyReturnDate	Jun. 30, 2009
Highest Quarterly Return	rr_BarChartHighestQuarterlyReturn	14.93%
Lowest Quarterly Return, Label	rr_LowestQuarterlyReturnLabel	Worst Quarter:
Lowest Quarterly Return, Date	rr_BarChartLowestQuarterlyReturnDate	Dec. 31, 2008
Lowest Quarterly Return	rr_BarChartLowestQuarterlyReturn	(12.96%)
Janus High-Yield Fund | Class D Shares | Return Before Taxes | Class D
Risk/Return:	rr_RiskReturnAbstract
Column	rr_AverageAnnualReturnColumnName	Class D Shares
Label	rr_AverageAnnualReturnLabel	Return Before Taxes
1 Year	rr_AverageAnnualReturnYear01	14.40%
5 Years	rr_AverageAnnualReturnYear05	9.24%
10 Years	rr_AverageAnnualReturnYear10	8.62%
Since Inception	rr_AverageAnnualReturnSinceInception	8.22%
Inception Date	rr_AverageAnnualReturnInceptionDate	Dec. 29, 1995
Janus High-Yield Fund | Class D Shares | Return After Taxes on Distributions | Class D
Risk/Return:	rr_RiskReturnAbstract
Column	rr_AverageAnnualReturnColumnName	Class D Shares
Label	rr_AverageAnnualReturnLabel	Return After Taxes on Distributions
1 Year	rr_AverageAnnualReturnYear01	11.70%
5 Years	rr_AverageAnnualReturnYear05	5.99%
10 Years	rr_AverageAnnualReturnYear10	5.67%
Since Inception	rr_AverageAnnualReturnSinceInception	4.96%
Inception Date	rr_AverageAnnualReturnInceptionDate	Dec. 29, 1995
Janus High-Yield Fund | Class D Shares | Return After Taxes on Distributions and Sale of Fund Shares | Class D
Risk/Return:	rr_RiskReturnAbstract
Column	rr_AverageAnnualReturnColumnName	Class D Shares
Label	rr_AverageAnnualReturnLabel	Return After Taxes on Distributions and Sale of Fund Shares	[1]
1 Year	rr_AverageAnnualReturnYear01	9.30%
5 Years	rr_AverageAnnualReturnYear05	5.89%
10 Years	rr_AverageAnnualReturnYear10	5.60%
Since Inception	rr_AverageAnnualReturnSinceInception	4.99%
Inception Date	rr_AverageAnnualReturnInceptionDate	Dec. 29, 1995
Janus High-Yield Fund | Class D Shares | Barclays U.S. Corporate High-Yield Bond Index (reflects no deduction for expenses, fees, or taxes)
Risk/Return:	rr_RiskReturnAbstract
Label	rr_AverageAnnualReturnLabel	Barclays U.S. Corporate High-Yield Bond Index
1 Year	rr_AverageAnnualReturnYear01	15.81%
5 Years	rr_AverageAnnualReturnYear05	10.34%
10 Years	rr_AverageAnnualReturnYear10	10.62%
Since Inception	rr_AverageAnnualReturnSinceInception	7.66%
Inception Date	rr_AverageAnnualReturnInceptionDate	Dec. 29, 1995

[1] If the Fund incurs a loss, which generates a tax benefit, the Return After Taxes on Distributions and Sale of Fund Shares may exceed the Fund’s other return figures.

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Janus Global Bond Fund | Class D Shares

FUND SUMMARY

Janus Global Bond Fund

INVESTMENT OBJECTIVE

Janus Global Bond Fund seeks total return, consistent with preservation of capital.

FEES AND EXPENSES OF THE FUND

This table describes the fees and expenses that you may pay if you buy and hold Shares of the Fund.

ANNUAL FUND OPERATING EXPENSES
(expenses that you pay each year as a percentage of the value of your investment)

Annual Fund Operating Expenses		Janus Global Bond Fund Class D Shares Class D
Operating Expenses Column [Text]		Class D
Management Fees		0.60%
Other Expenses	[1]	0.38%
Total Annual Fund Operating Expenses	[2]	0.98%
Fee Waiver	[2]	0.10%
Total Annual Fund Operating Expenses After Fee Waiver	[2]	0.88%

EXAMPLE:

The following Example is based on expenses without waivers. The Example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds.

The Example assumes that you invest $10,000 in the Fund for the time periods indicated, reinvest all dividends and distributions, and then redeem all of your Shares at the end of each period. The Example also assumes that your investment has a 5% return each year and that the Fund’s operating expenses without waivers or recoupments (if applicable) remain the same. Although your actual costs may be higher or lower, based on these assumptions your costs would be:

Expense Example (USD $)	Expense Example, By Year, Column [Text]	1 Year	3 Years	5 Years	10 Years
Janus Global Bond Fund Class D Shares Class D	Class D Shares	100	312	542	1,201

Portfolio Turnover: 

The Fund pays transaction costs, such as commissions, when it buys and sells securities (or “turns over” its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when Fund shares are held in a taxable account. These costs, which are not reflected in annual fund operating expenses or in the Example, affect the Fund’s performance. During the most recent fiscal year, the Fund’s portfolio turnover rate was 182% of the average value of its portfolio.

PRINCIPAL INVESTMENT STRATEGIES

The Fund pursues its investment objective by investing, under normal circumstances, at least 80% of its net assets in bonds. Bonds include, but are not limited to, corporate bonds, government notes and bonds, convertible bonds, mortgage-backed securities, and zero-coupon bonds. The Fund invests in corporate debt securities of issuers in a number of different countries, which may include the United States. The Fund invests in securities of issuers that are economically tied to developed and emerging market countries. The Fund may invest across all fixed-income sectors, including U.S. and non-U.S. government securities. The Fund’s investments may be denominated in local currency or U.S. dollar-denominated. The Fund may invest in debt securities with a range of maturities from short- to long-term. The Fund may invest up to 35% of its net assets in high-yield/high-risk debt securities. The Fund may also invest in preferred and common stock, money market instruments, municipal bonds, commercial and residential mortgage-backed securities, asset-backed securities, other securitized and structured debt products, private placements, and other investment companies, including exchange-traded funds (“ETFs”). The Fund may also invest in bank loans, euro-denominated obligations, buy backs or dollar rolls, when-issued securities, and reverse repurchase agreements. Due to the nature of securities in which the Fund invests, it may have relatively high portfolio turnover compared to other funds.

In addition, the Fund may invest its assets in derivatives, which are instruments that have a value derived from, or directly linked to, an underlying asset, such as equity securities, fixed-income securities, commodities, currencies, interest rates, or market indices, as substitutes for securities in which the Fund invests. The Fund has invested in and is expected to continue to invest in collateralized forward foreign currency exchange contracts, futures, options, and swaps (including interest rate swaps, total return swaps, and credit default swaps) for hedging purposes (to offset risks associated with an investment, currency exposure, or market conditions) and to increase or decrease the Fund’s exposure to a particular market, to manage or adjust the risk profile of the Fund related to an investment or currency exposure, to adjust its currency exposure relative to its benchmark index, and to earn income and enhance returns. In particular, the Fund may use interest rate futures to manage portfolio risk. The Fund’s exposure to derivatives will vary, is not limited to those derivatives listed, and could be significant at times. For purposes of meeting its 80% investment policy, the Fund may include derivatives that have characteristics similar to the securities in which the Fund may directly invest.

In addition to considering economic factors such as the effect of interest rates on the Fund’s investments, the portfolio managers apply a “bottom up” approach in choosing investments. This means that the portfolio managers look at income-producing securities one at a time to determine if a security is an attractive investment opportunity and if it is consistent with the Fund’s investment policies.

The Fund may lend portfolio securities on a short-term or long-term basis, in an amount equal to up to 1/3 of its total assets as determined at the time of the loan origination.

PRINCIPAL INVESTMENT RISKS

Although the Fund may be less volatile than funds that invest most of their assets in common stocks, the Fund’s returns and yields will vary, and you could lose money.

Fixed-Income Securities Risk. The Fund invests in a variety of fixed-income securities. Typically, the values of fixed-income securities change inversely with prevailing interest rates. Therefore, a fundamental risk of fixed-income securities is interest rate risk, which is the risk that the value of such securities will generally decline as prevailing interest rates rise, which may cause the Fund’s net asset value to likewise decrease. How specific fixed-income securities may react to changes in interest rates will depend on the specific characteristics of each security. Fixed-income securities are also subject to credit risk, prepayment risk, valuation risk, and liquidity risk. Credit risk is the risk that the credit strength of an issuer of a fixed-income security will weaken and/or that the issuer will be unable to make timely principal and interest payments and that the security may go into default. Prepayment risk is the risk that during periods of falling interest rates, certain fixed-income securities with higher interest rates, such as mortgage- and asset-backed securities, may be prepaid by their issuers thereby reducing the amount of interest payments. Valuation risk is the risk that one or more of the fixed-income securities in which the Fund invests are priced differently than the value realized upon such security’s sale. In times of market instability, valuation may be more difficult. Liquidity risk is the risk that fixed-income securities may be difficult or impossible to sell at the time that the portfolio managers would like or at the price the portfolio managers believe the security is currently worth.

Foreign Exposure Risk. The Fund normally has significant exposure to foreign markets as a result of its investments in foreign securities, including investments in emerging markets, which can be more volatile than the U.S. markets. As a result, its returns and net asset value may be affected to a large degree by fluctuations in currency exchange rates or political or economic conditions in a particular country. In some foreign markets, there may not be protection against failure by other parties to complete transactions. It may not be possible for the Fund to repatriate capital, dividends, interest, and other income from a particular country or governmental entity. In addition, a market swing in one or more countries or regions where the Fund has invested a significant amount of its assets may have a greater effect on the Fund’s performance than it would in a more geographically diversified portfolio. The Fund’s investments in emerging market countries may involve risks greater than, or in addition to, the risks of investing in more developed countries. To the extent the Fund invests in foreign debt securities, such investments are sensitive to changes in interest rates. Additionally, investments in securities of foreign governments involve the risk that a foreign government may not be willing or able to pay interest or repay principal when due.

Eurozone Risk. A number of countries in the European Union (“EU”) have experienced severe economic and financial difficulties. As a result, financial markets in the EU have been subject to extreme volatility and declines in asset values and liquidity. Responses to these financial problems by European governments, central banks, and others, including austerity measures and reforms, may not work, may result in social unrest, and may limit future growth and economic recovery or have other unintended consequences. Further defaults or restructurings by governments and others of their debt could have additional adverse effects on economies, financial markets, and asset valuations around the world. To the extent that the Fund has exposure to European markets or to transactions tied to the value of the euro, these events could negatively affect the value and liquidity of the Fund’s investments.

Emerging Markets Risk. The risks of foreign investing mentioned above are heightened when investing in emerging markets. Emerging markets securities involve a number of additional risks, which may result from less government supervision and regulation of business and industry practices (including the potential lack of strict finance and accounting controls and standards), stock exchanges, brokers, and listed companies, making these investments potentially more volatile in price and less liquid than investments in developed securities markets, resulting in greater risk to investors. There is a risk in developing countries that a future economic or political crisis could lead to price controls, forced mergers of companies, expropriation or confiscatory taxation, imposition or enforcement of foreign ownership limits, seizure, nationalization, or creation of government monopolies, any of which may have a detrimental effect on the Fund’s investments. In addition, the Fund’s investments may be denominated in foreign currencies and therefore, changes in the value of a country’s currency compared to the U.S. dollar may affect the value of the Fund’s investments. To the extent that the Fund invests a significant portion of its assets in the securities of issuers in or companies of a single country or region, it is more likely to be impacted by events or conditions affecting that country or region, which could have a negative impact on the Fund’s performance. Some of the risks of investing directly in foreign and emerging market securities may be reduced when the Fund invests indirectly in foreign securities through various other investment vehicles including derivatives, which also involve other risks. As of June 30, 2013, approximately 4.2% of the Fund’s investments were in emerging markets.

Mortgage-Backed Securities Risk. Mortgage-backed securities are classified generally as either commercial mortgage-backed securities or residential mortgage-backed securities, each of which is subject to certain specific risks. Mortgage-backed securities tend to be more sensitive to changes in interest rates than other types of debt securities. Investments in mortgage-backed securities are subject to both extension risk, where borrowers extend the duration of their mortgages in times of rising interest rates, and prepayment risk, where borrowers pay off their mortgages sooner than expected in times of declining interest rates. These risks may reduce the Fund’s returns. In addition, investments in mortgage-backed securities, including those comprised of subprime mortgages, may be subject to a higher degree of credit risk, valuation risk, and liquidity risk than various other types of fixed-income securities.

Sovereign Debt Risk. The Fund may invest in U.S. and foreign government debt securities (“sovereign debt”). Investments in U.S. sovereign debt are considered low risk. However, investments in non-U.S. sovereign debt can involve a high degree of risk, including the risk that the governmental entity that controls the repayment of sovereign debt may not be willing or able to repay the principal and/or to pay the interest on its sovereign debt in a timely manner. A sovereign debtor’s willingness or ability to satisfy its debt obligation may be affected by various factors including, but not limited to, its cash flow situation, the extent of its foreign currency reserves, the availability of foreign exchange when a payment is due, and the relative size of its debt position in relation to its economy as a whole. In the event of default, there may be limited or no legal remedies for collecting sovereign debt and there may be no bankruptcy proceedings through which the Fund may collect all or part of the sovereign debt that a governmental entity has not repaid.

High-Yield/High-Risk Bond Risk. High-yield/high-risk bonds (also known as “junk” bonds) may be more sensitive than other types of bonds to economic changes, political changes, or adverse developments specific to the company that issued the bond, which may adversely affect their value.

Bank Loan Risk. Bank loans are obligations of companies or other entities entered into in connection with recapitalizations, acquisitions, and refinancings. The Fund’s investments in bank loans are generally acquired as a participation interest in, or assignment of, loans originated by a lender or other financial institution. These investments may include institutionally-traded floating and fixed-rate debt securities. Participation interests and assignments involve credit, interest rate, and liquidity risk. In addition, the bank loans underlying these securities often involve borrowers with low credit ratings whose financial conditions are troubled or uncertain, including companies that are highly leveraged or in bankruptcy proceedings.

Exchange-Traded Funds Risk. The Fund may purchase shares of exchange-traded funds (“ETFs”) to gain exposure to a particular portion of the market. ETFs are pooled investment vehicles, which may be managed or unmanaged, that generally seek to track the performance of a specific index. ETFs are traded on an exchange at market prices that may vary from the net asset value of their underlying investments. When the Fund invests in an ETF, in addition to directly bearing the expenses associated with its own operations, it will bear a pro rata portion of the ETF’s expenses. ETFs have certain inherent risks generally associated with investments in a portfolio of securities in which the ETF is invested, including the risk that the general level of stock prices may decline, thereby adversely affecting the value of each unit of the ETF. ETFs also involve the risk that an active trading market for an ETF’s shares may not develop or be maintained.

Derivatives Risk. Derivatives can be highly volatile and involve risks in addition to the risks of the underlying referenced securities. Gains or losses from a derivative investment can be substantially greater than the derivative’s original cost, and can therefore involve leverage. Leverage may cause the Fund to be more volatile than if it had not used leverage. Derivatives can be complex instruments and may involve analysis that differs from that required for other investment types used by the Fund. If the value of a derivative does not correlate well with the particular market or other asset class to which the derivative is intended to provide exposure, the derivative may not produce the anticipated result. Derivatives can also reduce the opportunity for gain or result in losses by offsetting positive returns in other investments. Derivatives can be less liquid than other types of investments and entail the risk that the counterparty will default on its payment obligations. If the counterparty to a derivative transaction defaults, the Fund would risk the loss of the net amount of the payments that it contractually is entitled to receive. To the extent the Fund enters into short derivative positions, the Fund may be exposed to risks similar to those associated with short sales, including the risk that the Fund’s losses are theoretically unlimited.

Portfolio Turnover Risk. Increased portfolio turnover may result in higher costs, which may have a negative effect on the Fund’s performance. In addition, higher portfolio turnover may result in the acceleration of capital gains and the recognition of greater levels of short-term capital gains, which are taxed at ordinary federal income tax rates when distributed to shareholders.

Securities Lending Risk. The Fund may seek to earn additional income through lending its securities to certain qualified broker-dealers and institutions. There is the risk that when portfolio securities are lent, the securities may not be returned on a timely basis, and the Fund may experience delays and costs in recovering the security or gaining access to the collateral provided to the Fund to collateralize the loan. If the Fund is unable to recover a security on loan, the Fund may use the collateral to purchase replacement securities in the market. There is a risk that the value of the collateral could decrease below the cost of the replacement security by the time the replacement investment is made, resulting in a loss to the Fund.

An investment in the Fund is not a bank deposit and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency.

PERFORMANCE INFORMATION

The following information provides some indication of the risks of investing in the Fund by showing how the Fund’s performance has varied over time. The bar chart depicts the change in performance from year to year during the periods indicated. The table compares the Fund’s average annual returns for the periods indicated to broad-based securities market indices. The indices are not actively managed and are not available for direct investment. All figures assume reinvestment of dividends and distributions. For certain periods, the Fund’s performance reflects the effect of expense waivers. Without the effect of these expense waivers, the performance shown would have been lower.

The Fund’s past performance (before and after taxes) does not necessarily indicate how it will perform in the future. Updated performance information is available at janus.com/allfunds or by calling 1-800-525-3713.

Annual Total Returns for Class D Shares (calendar year-end)

Best Quarter:  Third Quarter 2012  4.33%          Worst Quarter:  Fourth Quarter 2012  0.18%

The Fund’s year-to-date return as of the calendar quarter ended September 30, 2013 was −3.24%.

Average Annual Total Returns (periods ended 12/31/12)

Average Annual Total Returns Janus Global Bond Fund Class D Shares	Column	Label	1 Year	Since Inception	Inception Date
Class D Return Before Taxes	Class D Shares	Return Before Taxes	8.01%	7.30%	Dec. 28, 2010
Class D Return After Taxes on Distributions	Class D Shares	Return After Taxes on Distributions	6.18%	5.72%	Dec. 28, 2010
Class D Return After Taxes on Distributions and Sale of Fund Shares	Class D Shares	Return After Taxes on Distributions and Sale of Fund Shares	5.33%	5.34%	Dec. 28, 2010
Barclays Global Aggregate Bond Index (reflects no deduction for expenses, fees, or taxes)		Barclays Global Aggregate Bond Index	4.32%	5.74%	Dec. 28, 2010
Barclays Global Aggregate Corporate Bond Index (reflects no deduction for expenses, fees, or taxes)		Barclays Global Aggregate Corporate Bond Index	11.21%	8.59%	Dec. 28, 2010

After-tax returns are calculated using the historically highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes. Actual after-tax returns depend on your individual tax situation and may differ from those shown in the preceding table. The after-tax return information shown above does not apply to Fund shares held through a tax-deferred account, such as a 401(k) plan or an IRA.

[1] Other Expenses are based on the estimated expenses that the Fund expects to incur.

[2] Janus Capital has contractually agreed to waive its investment advisory fee and/or reimburse Fund expenses to the extent that the Fund’s total annual fund operating expenses (excluding administrative services fees payable pursuant to the Transfer Agency Agreement, brokerage commissions, interest, dividends, taxes, acquired fund fees and expenses, and extraordinary expenses) exceed 0.75% until at least November 1, 2014. The contractual waiver may be terminated or modified prior to this date only at the discretion of the Board of Trustees. For a period of three years subsequent to the Fund’s commencement of operations (December 28, 2010) or until the Fund’s assets exceed the first breakpoint in the investment advisory fee schedule, whichever occurs first, Janus Capital may recover from the Fund fees and expenses previously waived or reimbursed, which could then be considered a deferral, if the Fund’s expense ratio, including recovered expenses, falls below the expense limit.

XML

Label	Element	Value
Risk/Return:	rr_RiskReturnAbstract
Registrant Name	dei_EntityRegistrantName	JANUS INVESTMENT FUND
Prospectus Date	rr_ProspectusDate	Oct. 28, 2013
INTECH Global Dividend Fund | Class D Shares
Risk/Return:	rr_RiskReturnAbstract
Risk/Return [Heading]	rr_RiskReturnHeading	FUND SUMMARY INTECH Global Dividend Fund
Objective [Heading]	rr_ObjectiveHeading	INVESTMENT OBJECTIVE
Objective, Primary [Text Block]	rr_ObjectivePrimaryTextBlock	INTECH Global Dividend Fund seeks long-term growth of capital and income.
Expense [Heading]	rr_ExpenseHeading	FEES AND EXPENSES OF THE FUND
Expense Narrative [Text Block]	rr_ExpenseNarrativeTextBlock	This table describes the fees and expenses that you may pay if you buy and hold Shares of the Fund.
Operating Expenses Caption [Text]	rr_OperatingExpensesCaption	ANNUAL FUND OPERATING EXPENSES (expenses that you pay each year as a percentage of the value of your investment)
Fee Waiver or Reimbursement over Assets, Date of Termination	rr_FeeWaiverOrReimbursementOverAssetsDateOfTermination	November 1, 2014
Portfolio Turnover [Heading]	rr_PortfolioTurnoverHeading	Portfolio Turnover:
Portfolio Turnover [Text Block]	rr_PortfolioTurnoverTextBlock	The Fund pays transaction costs, such as commissions, when it buys and sells securities (or “turns over” its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when Fund shares are held in a taxable account. These costs, which are not reflected in annual fund operating expenses or in the Example, affect the Fund’s performance. During the most recent fiscal year, the Fund’s portfolio turnover rate was 116% of the average value of its portfolio.
Portfolio Turnover, Rate	rr_PortfolioTurnoverRate	116.00%
Expense Example [Heading]	rr_ExpenseExampleHeading	EXAMPLE:
Expense Example by Year [Heading]	rr_ExpenseExampleByYearHeading	The Example assumes that you invest $10,000 in the Fund for the time periods indicated, reinvest all dividends and distributions, and then redeem all of your Shares at the end of each period. The Example also assumes that your investment has a 5% return each year and that the Fund’s operating expenses without waivers or recoupments (if applicable) remain the same. Although your actual costs may be higher or lower, based on these assumptions your costs would be:
Expense Example Narrative [Text Block]	rr_ExpenseExampleNarrativeTextBlock	The following Example is based on expenses without waivers. The Example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds.
Strategy [Heading]	rr_StrategyHeading	PRINCIPAL INVESTMENT STRATEGIES
Strategy Narrative [Text Block]	rr_StrategyNarrativeTextBlock	The Fund invests, under normal circumstances, at least 80% of its net assets in dividend-paying securities. The Fund invests primarily in common stocks from the universe of the Morgan Stanley Capital International (“MSCI”) World High Dividend Yield Index, utilizing INTECH’s mathematical investment process. The MSCI World High Dividend Yield Index is designed to reflect the performance of the high dividend yield securities contained within the broader MSCI World IndexSM. The Fund may also invest in foreign equity and debt securities. The Fund pursues its investment objective by applying a mathematical investment process to construct an investment portfolio from the universe of common stocks within its named benchmark index. The goal of this process is to build a portfolio of stocks in a more efficient combination than the named benchmark index. The process seeks to capitalize on the natural volatility of the market by searching for stocks within the index that have high relative volatility (providing the potential for excess returns) but that essentially move in opposite directions or have low correlation to each other (providing the potential for lower relative risk). By constructing the portfolio in this manner and periodically rebalancing the portfolio to maintain potentially more efficient weightings, INTECH’s mathematical investment process seeks to create a portfolio that, over time, produces returns in excess of its named benchmark index with risks similar to that of the benchmark index. The rebalancing techniques used by INTECH may result in a higher portfolio turnover compared to a “buy and hold” fund strategy. The Fund may lend portfolio securities on a short-term or long-term basis, in an amount equal to up to 1/3 of its total assets as determined at the time of the loan origination.
Risk [Heading]	rr_RiskHeading	PRINCIPAL INVESTMENT RISKS
Risk Narrative [Text Block]	rr_RiskNarrativeTextBlock	The biggest risk is that the Fund’s returns will vary, and you could lose money. The Fund is designed for long-term investors seeking an equity portfolio, including common stocks. Common stocks tend to be more volatile than many other investment choices. Foreign Exposure Risk. The Fund normally has significant exposure to foreign markets as a result of its investments in foreign securities, which can be more volatile than the U.S. markets. As a result, its returns and net asset value may be affected to a large degree by fluctuations in currency exchange rates or political or economic conditions in a particular country. In some foreign markets, there may not be protection against failure by other parties to complete transactions. It may not be possible for the Fund to repatriate capital, dividends, interest, and other income from a particular country or governmental entity. In addition, a market swing in one or more countries or regions where the Fund has invested a significant amount of its assets may have a greater effect on the Fund’s performance than it would in a more geographically diversified portfolio. To the extent the Fund invests in foreign debt securities, such investments are sensitive to changes in interest rates. Additionally, investments in securities of foreign governments involve the risk that a foreign government may not be willing or able to pay interest or repay principal when due. Eurozone Risk. A number of countries in the European Union (“EU”) have experienced severe economic and financial difficulties. As a result, financial markets in the EU have been subject to extreme volatility and declines in asset values and liquidity. Responses to these financial problems by European governments, central banks, and others, including austerity measures and reforms, may not work, may result in social unrest, and may limit future growth and economic recovery or have other unintended consequences. Further defaults or restructurings by governments and others of their debt could have additional adverse effects on economies, financial markets, and asset valuations around the world. To the extent that the Fund has exposure to European markets or to transactions tied to the value of the euro, these events could negatively affect the value and liquidity of the Fund’s investments. Dividend Risk. Companies that issue dividend-yielding securities are not required to continue to pay dividends on such securities. Therefore, there is the possibility that such companies could reduce or eliminate the payment of dividends in the future. Market Risk. The value of the Fund’s portfolio may decrease if the value of an individual company or security, or multiple companies or securities, in the portfolio decreases. Further, regardless of how well individual companies or securities perform, the value of the Fund’s portfolio could also decrease if there are deteriorating economic or market conditions. It is important to understand that the value of your investment may fall, sometimes sharply, in response to changes in the market, and you could lose money. Investment Process Risk. The proprietary mathematical investment process used by INTECH may not achieve the desired results. There is a risk that INTECH’s method of identifying stocks with higher volatility than the named benchmark index or its method of identifying stocks that tend to move in the same or opposite direction relative to each other (correlation) will not result in selecting stocks with continuing volatility or the expected correlation. In INTECH’s history, which spans more than 25 years, INTECH’s mathematical investment process has experienced periods of both underperformance and outperformance relative to an identified benchmark. Even when the proprietary mathematical investment process is working appropriately, INTECH expects that there will be periods of underperformance relative to the benchmark. On an occasional basis, INTECH makes changes to its mathematical investment process. These changes may result in changes to the portfolio, might not provide the intended results, and may adversely impact the Fund’s performance. Portfolio Turnover Risk. Increased portfolio turnover may result in higher costs, which may have a negative effect on the Fund’s performance. In addition, higher portfolio turnover may result in the acceleration of capital gains and the recognition of greater levels of short-term capital gains, which are taxed at ordinary federal income tax rates when distributed to shareholders. Securities Lending Risk. The Fund may seek to earn additional income through lending its securities to certain qualified broker-dealers and institutions. There is the risk that when portfolio securities are lent, the securities may not be returned on a timely basis, and the Fund may experience delays and costs in recovering the security or gaining access to the collateral provided to the Fund to collateralize the loan. If the Fund is unable to recover a security on loan, the Fund may use the collateral to purchase replacement securities in the market. There is a risk that the value of the collateral could decrease below the cost of the replacement security by the time the replacement investment is made, resulting in a loss to the Fund. An investment in the Fund is not a bank deposit and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency.
Risk Lose Money [Text]	rr_RiskLoseMoney	The biggest risk is that the Fund's returns will vary, and you could lose money.
Risk Not Insured Depository Institution [Text]	rr_RiskNotInsuredDepositoryInstitution	An investment in the Fund is not a bank deposit and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency.
Bar Chart and Performance Table [Heading]	rr_BarChartAndPerformanceTableHeading	PERFORMANCE INFORMATION
Performance Narrative [Text Block]	rr_PerformanceNarrativeTextBlock	The following information provides some indication of the risks of investing in the Fund by showing how the Fund’s performance has varied over time. The bar chart depicts the Fund’s performance during the period indicated. The table compares the Fund’s average annual returns for the periods indicated to broad-based securities market indices. The indices are not actively managed and are not available for direct investment. All figures assume reinvestment of dividends and distributions. For certain periods, the Fund’s performance reflects the effect of expense waivers. Without the effect of these expense waivers, the performance shown would have been lower. The Fund’s past performance (before and after taxes) does not necessarily indicate how it will perform in the future. Updated performance information is available at janus.com/allfunds or by calling 1-800-525-3713.
Performance Information Illustrates Variability of Returns [Text]	rr_PerformanceInformationIllustratesVariabilityOfReturns	The following information provides some indication of the risks of investing in the Fund by showing how the Fund’s performance has varied over time. The bar chart depicts the Fund’s performance during the period indicated.
Performance Additional Market Index [Text]	rr_PerformanceAdditionalMarketIndex	The table compares the Fund’s average annual returns for the periods indicated to broad-based securities market indices. The indices are not actively managed and are not available for direct investment. All figures assume reinvestment of dividends and distributions.
Performance Availability Phone [Text]	rr_PerformanceAvailabilityPhone	1-800-525-3713
Performance Availability Website Address [Text]	rr_PerformanceAvailabilityWebSiteAddress	janus.com/allfunds
Performance Past Does Not Indicate Future [Text]	rr_PerformancePastDoesNotIndicateFuture	The Fund’s past performance (before and after taxes) does not necessarily indicate how it will perform in the future.
Bar Chart [Heading]	rr_BarChartHeading	Annual Total Returns for Class D Shares (calendar year-end)
Bar Chart Closing [Text Block]	rr_BarChartClosingTextBlock	Best Quarter:  Third Quarter 2012  5.87%          Worst Quarter:  Second Quarter 2012  −2.75%
Year to Date Return, Label	rr_YearToDateReturnLabel	The Fund’s year-to-date return as of the calendar quarter ended September 30, 2013 was 12.74%.
Performance Table Heading	rr_PerformanceTableHeading	Average Annual Total Returns (periods ended 12/31/12)
Performance Table Uses Highest Federal Rate	rr_PerformanceTableUsesHighestFederalRate	After-tax returns are calculated using the historically highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes.
Performance Table Not Relevant to Tax Deferred	rr_PerformanceTableNotRelevantToTaxDeferred	Actual after-tax returns depend on your individual tax situation and may differ from those shown in the preceding table. The after-tax return information shown above does not apply to Fund shares held through a tax-deferred account, such as a 401(k) plan or an IRA.
Performance Table Narrative	rr_PerformanceTableNarrativeTextBlock	After-tax returns are calculated using the historically highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes. Actual after-tax returns depend on your individual tax situation and may differ from those shown in the preceding table. The after-tax return information shown above does not apply to Fund shares held through a tax-deferred account, such as a 401(k) plan or an IRA.
Performance Table Closing [Text Block]	rr_PerformanceTableClosingTextBlock	Updated performance information is available at janus.com/allfunds or by calling 1-800-525-3713.
INTECH Global Dividend Fund | Class D Shares | Class D
Risk/Return:	rr_RiskReturnAbstract
Operating Expenses Column [Text]	rr_OperatingExpensesColumnName	Class D
Management Fees	rr_ManagementFeesOverAssets	0.55%
Other Expenses	rr_OtherExpensesOverAssets	2.02%
Total Annual Fund Operating Expenses	rr_ExpensesOverAssets	2.57%	[1]
Fee Waiver	rr_FeeWaiverOrReimbursementOverAssets	1.92%	[1]
Total Annual Fund Operating Expenses After Fee Waiver	rr_NetExpensesOverAssets	0.65%	[1]
Expense Example, By Year, Column [Text]	rr_ExpenseExampleByYearColumnName	Class D Shares
1 Year	rr_ExpenseExampleYear01	$ 260
3 Years	rr_ExpenseExampleYear03	799
5 Years	rr_ExpenseExampleYear05	1,365
10 Years	rr_ExpenseExampleYear10	$ 2,905
2012	rr_AnnualReturn2012	11.90%
Bar Chart, Year to Date Return, Date	rr_BarChartYearToDateReturnDate	Sep. 30, 2013
Bar Chart, Year to Date Return	rr_BarChartYearToDateReturn	12.74%
Highest Quarterly Return, Label	rr_HighestQuarterlyReturnLabel	Best Quarter:
Highest Quarterly Return, Date	rr_BarChartHighestQuarterlyReturnDate	Sep. 30, 2012
Highest Quarterly Return	rr_BarChartHighestQuarterlyReturn	5.87%
Lowest Quarterly Return, Label	rr_LowestQuarterlyReturnLabel	Worst Quarter:
Lowest Quarterly Return, Date	rr_BarChartLowestQuarterlyReturnDate	Jun. 30, 2012
Lowest Quarterly Return	rr_BarChartLowestQuarterlyReturn	(2.75%)
INTECH Global Dividend Fund | Class D Shares | Return Before Taxes | Class D
Risk/Return:	rr_RiskReturnAbstract
Column	rr_AverageAnnualReturnColumnName	Class D Shares
Label	rr_AverageAnnualReturnLabel	Return Before Taxes
1 Year	rr_AverageAnnualReturnYear01	11.90%
Since Inception	rr_AverageAnnualReturnSinceInception	14.70%
Inception Date	rr_AverageAnnualReturnInceptionDate	Dec. 15, 2011
INTECH Global Dividend Fund | Class D Shares | Return After Taxes on Distributions | Class D
Risk/Return:	rr_RiskReturnAbstract
Column	rr_AverageAnnualReturnColumnName	Class D Shares
Label	rr_AverageAnnualReturnLabel	Return After Taxes on Distributions
1 Year	rr_AverageAnnualReturnYear01	11.19%
Since Inception	rr_AverageAnnualReturnSinceInception	13.96%
Inception Date	rr_AverageAnnualReturnInceptionDate	Dec. 15, 2011
INTECH Global Dividend Fund | Class D Shares | Return After Taxes on Distributions and Sale of Fund Shares | Class D
Risk/Return:	rr_RiskReturnAbstract
Column	rr_AverageAnnualReturnColumnName	Class D Shares
Label	rr_AverageAnnualReturnLabel	Return After Taxes on Distributions and Sale of Fund Shares
1 Year	rr_AverageAnnualReturnYear01	8.33%
Since Inception	rr_AverageAnnualReturnSinceInception	12.30%
Inception Date	rr_AverageAnnualReturnInceptionDate	Dec. 15, 2011
INTECH Global Dividend Fund | Class D Shares | Morgan Stanley Capital International World Index℠ (net of foreign withholding taxes) (reflects no deduction for expenses, fees, or taxes, except foreign withholding taxes)
Risk/Return:	rr_RiskReturnAbstract
Label	rr_AverageAnnualReturnLabel	Morgan Stanley Capital International World Index℠ (net of foreign withholding taxes)
1 Year	rr_AverageAnnualReturnYear01	15.83%
Since Inception	rr_AverageAnnualReturnSinceInception	19.02%
Inception Date	rr_AverageAnnualReturnInceptionDate	Dec. 15, 2011
INTECH Global Dividend Fund | Class D Shares | Morgan Stanley Capital International World High Dividend Yield Index (net of foreign withholding taxes) (reflects no deduction for expenses, fees, or taxes, except foreign withholding taxes)
Risk/Return:	rr_RiskReturnAbstract
Label	rr_AverageAnnualReturnLabel	Morgan Stanley Capital International World High Dividend Yield Index (net of foreign withholding taxes)
1 Year	rr_AverageAnnualReturnYear01	12.24%
Since Inception	rr_AverageAnnualReturnSinceInception	15.80%
Inception Date	rr_AverageAnnualReturnInceptionDate	Dec. 15, 2011

[1] Janus Capital has contractually agreed to waive its investment advisory fee and/or reimburse Fund expenses to the extent that the Fund’s total annual fund operating expenses (excluding administrative services fees payable pursuant to the Transfer Agency Agreement, brokerage commissions, interest, dividends, taxes, acquired fund fees and expenses, and extraordinary expenses) exceed 0.50% until at least November 1, 2014. The contractual waiver may be terminated or modified prior to this date only at the discretion of the Board of Trustees. For a period of three years subsequent to the Fund’s commencement of operations (December 15, 2011), Janus Capital may recover from the Fund fees and expenses previously waived or reimbursed, which could then be considered a deferral, if the Fund’s expense ratio, including recovered expenses, falls below the expense limit.

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Perkins Select Value Fund | Class A, C, S, I, N, T Shares

FUND SUMMARY

Perkins Select Value Fund

INVESTMENT OBJECTIVE

Perkins Select Value Fund seeks capital appreciation.

FEES AND EXPENSES OF THE FUND

This table describes the fees and expenses that you may pay if you buy and hold Shares of the Fund. Each share class has different expenses, but represents an investment in the same Fund.

For Class A Shares, you may qualify for sales charge discounts if you and your family invest, or agree to invest in the future, at least $50,000 in the Fund or in other Janus mutual funds. More information about these and other discounts, as well as eligibility requirements for each share class, is available from your financial professional and in the “Purchases” section on page 66 of the Fund’s Prospectus and in the “Purchases” section on page 70 of the Fund’s Statement of Additional Information.

SHAREHOLDER FEES
(fees paid directly from your investment)

Shareholder Fees Perkins Select Value Fund Class A, C, S, I, N, T Shares	Class A	Class C	Class S	Class I	Class N	Class T
Shareholder Fees Column [Text]	Class A	Class C	Class S	Class I	Class N	Class T
Maximum Sales Charge (load) Imposed on Purchases (as a percentage of offering price)	5.75%	none	none	none	none	none
Maximum Deferred Sales Charge (load) (as a percentage of the lower of original purchase price or redemption proceeds)	none	1.00%	none	none	none	none

ANNUAL FUND OPERATING EXPENSES
(expenses that you pay each year as a percentage of the value of your investment)

Annual Fund Operating Expenses Perkins Select Value Fund Class A, C, S, I, N, T Shares		Class A	Class C	Class S	Class I	Class N		Class T
Operating Expenses Column [Text]		Class A	Class C	Class S	Class I	Class N		Class T
Management Fees (may adjust up or down)		0.63%	0.63%	0.63%	0.63%	0.63%		0.63%
Distribution/Service (12b-1) Fees		0.25%	1.00%	0.25%	none	none		none
Other Expenses		0.45%	0.40%	0.50%	0.24%	0.24%	[1]	0.48%
Total Annual Fund Operating Expenses	[2]	1.33%	2.03%	1.38%	0.87%	0.87%		1.11%
Fee Waiver	[2]	0.19%	0.20%	0.18%	0.17%	0.17%		0.16%
Total Annual Fund Operating Expenses After Fee Waiver	[2]	1.14%	1.83%	1.20%	0.70%	0.70%		0.95%

EXAMPLE:

The following Example is based on expenses without waivers. The Example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds.

The Example assumes that you invest $10,000 in the Fund for the time periods indicated and reinvest all dividends and distributions. The Example also assumes that your investment has a 5% return each year and that the Fund’s operating expenses without waivers remain the same. Although your actual costs may be higher or lower, based on these assumptions your costs would be:

If Shares are redeemed:

Expense Example Perkins Select Value Fund Class A, C, S, I, N, T Shares (USD $)	Expense Example, By Year, Column [Text]	1 Year	3 Years	5 Years	10 Years
Class A	Class A Shares	703	972	1,262	2,084
Class C	Class C Shares	306	637	1,093	2,358
Class S	Class S Shares	140	437	755	1,657
Class I	Class I Shares	89	278	482	1,073
Class N	Class N Shares	89	278	482	1,073
Class T	Class T Shares	113	353	612	1,352

If Shares are not redeemed:

Expense Example, No Redemption Perkins Select Value Fund Class A, C, S, I, N, T Shares (USD $)	Expense Example, No Redemption, By Year, Column [Text]	1 Year	3 Years	5 Years	10 Years
Class A	Class A Shares	703	972	1,262	2,084
Class C	Class C Shares	206	637	1,093	2,358
Class S	Class S Shares	140	437	755	1,657
Class I	Class I Shares	89	278	482	1,073
Class N	Class N Shares	89	278	482	1,073
Class T	Class T Shares	113	353	612	1,352

Portfolio Turnover:

The Fund pays transaction costs, such as commissions, when it buys and sells securities (or “turns over” its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when Fund shares are held in a taxable account. These costs, which are not reflected in annual fund operating expenses or in the Example, affect the Fund’s performance. During the most recent fiscal year, the Fund’s portfolio turnover rate was 62% of the average value of its portfolio.

PRINCIPAL INVESTMENT STRATEGIES

The Fund pursues its investment objective by investing primarily in common stocks in all capitalization ranges selected for their capital appreciation potential. The Fund primarily invests in the common stocks of companies of any size whose stock prices the portfolio managers believe to be undervalued. The Fund may also invest in foreign equity and debt securities, which may include investments in emerging markets. In addition, when the portfolio managers believe that market conditions are unfavorable for investing, or when they are otherwise unable to locate attractive investment opportunities, the Fund’s cash or similar investments may increase.

The Fund focuses on companies that have fallen out of favor with the market or that appear to be temporarily misunderstood by the investment community. The Fund’s portfolio managers generally look for companies with:

• strong balance sheets and solid recurring free cash flows
• attractive relative and absolute valuation ratios or that have underperformed recently
• favorable reward to risk characteristics

The Fund may invest its assets in derivatives, which are instruments that have a value derived from, or directly linked to, an underlying asset, such as equity securities, fixed-income securities, commodities, currencies, interest rates, or market indices, as substitutes for securities in which the Fund invests. The Fund may invest in derivative instruments (by taking long and/or short positions) for different purposes, including hedging (to offset risks associated with an investment, currency exposure, or market conditions) and to earn income and enhance returns.

PRINCIPAL INVESTMENT RISKS

The biggest risk is that the Fund’s returns will vary, and you could lose money. The Fund is designed for long-term investors seeking an equity portfolio, including common stocks. Common stocks tend to be more volatile than many other investment choices.

Value Investing Risk. Because different types of stocks tend to shift in and out of favor depending on market and economic conditions, “value” stocks may perform differently than other types of stocks and from the market as a whole, and can continue to be undervalued by the market for long periods of time. It is also possible that a value stock will never appreciate to the extent expected by the portfolio managers. When the Fund’s investments in cash or similar investments increase due to a lack of favorable investment opportunities or other extraordinary factors, the Fund may not participate in market advances or declines to the same extent that it would if the Fund had been fully invested.

Market Risk. The value of the Fund’s portfolio may decrease if the value of an individual company or security, or multiple companies or securities, in the portfolio decreases or if the portfolio managers’ belief about a company’s intrinsic worth is incorrect. Further, regardless of how well individual companies or securities perform, the value of the Fund’s portfolio could also decrease if there are deteriorating economic or market conditions. It is important to understand that the value of your investment may fall, sometimes sharply, in response to changes in the market, and you could lose money.

Foreign Exposure Risk. The Fund may have significant exposure to foreign markets as a result of its investments in foreign securities, including investments in emerging markets, which can be more volatile than the U.S. markets. As a result, its returns and net asset value may be affected to a large degree by fluctuations in currency exchange rates or political or economic conditions in a particular country. In some foreign markets, there may not be protection against failure by other parties to complete transactions. It may not be possible for the Fund to repatriate capital, dividends, interest, and other income from a particular country or governmental entity. In addition, a market swing in one or more countries or regions where the Fund has invested a significant amount of its assets may have a greater effect on the Fund’s performance than it would in a more geographically diversified portfolio. To the extent the Fund invests in foreign debt securities, such investments are sensitive to changes in interest rates. Additionally, investments in securities of foreign governments involve the risk that a foreign government may not be willing or able to pay interest or repay principal when due.

Eurozone Risk. A number of countries in the European Union (“EU”) have experienced severe economic and financial difficulties. As a result, financial markets in the EU have been subject to extreme volatility and declines in asset values and liquidity. Responses to these financial problems by European governments, central banks, and others, including austerity measures and reforms, may not work, may result in social unrest, and may limit future growth and economic recovery or have other unintended consequences. Further defaults or restructurings by governments and others of their debt could have additional adverse effects on economies, financial markets, and asset valuations around the world. To the extent that the Fund has exposure to European markets or to transactions tied to the value of the euro, these events could negatively affect the value and liquidity of the Fund’s investments.

Real Estate Securities Risk. The Fund’s performance may be affected by the risks associated with investments in real estate-related companies. The value of real estate-related companies’ securities is sensitive to changes in real estate values and rental income, property taxes, interest rates, tax and regulatory requirements, supply and demand, and the management skill and creditworthiness of the company. Investments in real estate investment trusts (“REITs”) involve the same risks as other real estate investments. In addition, a REIT could fail to qualify for tax-free pass-through of its income under the Internal Revenue Code or fail to maintain its exemption from registration under the Investment Company Act of 1940, as amended, which could produce adverse economic consequences for the REIT and its investors, including the Fund.

Derivatives Risk. Derivatives can be highly volatile and involve risks in addition to the risks of the underlying referenced securities. Gains or losses from a derivative investment can be substantially greater than the derivative’s original cost, and can therefore involve leverage. Leverage may cause the Fund to be more volatile than if it had not used leverage. Derivatives can be less liquid than other types of investments and entail the risk that the counterparty will default on its payment obligations.

An investment in the Fund is not a bank deposit and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency.

PERFORMANCE INFORMATION

The following information provides some indication of the risks of investing in the Fund by showing how the Fund’s performance has varied over time. Class A Shares, Class C Shares, Class S Shares, Class I Shares, and Class T Shares of the Fund commenced operations with the Fund’s inception.

• The performance shown for Class A Shares, Class C Shares, Class S Shares, Class I Shares, and Class T Shares is calculated using the fees and expenses of each respective share class, net of any applicable fee and expense limitations or waivers.
• The performance shown for Class N Shares reflects the performance of the Fund’s Class I Shares, calculated using the fees and expenses of Class N Shares, without the effect of any fee and expense limitations or waivers. If Class N Shares of the Fund had been available during the periods shown, the performance may have been different.

The bar chart depicts the Fund’s performance during the period indicated. The bar chart figures do not include any applicable sales charges that an investor may pay when they buy or sell Class A Shares or Class C Shares of the Fund. If sales charges were included, the returns would be lower. The table compares the Fund’s average annual returns for the periods indicated to a broad-based securities market index. The index is not actively managed and is not available for direct investment. All figures assume reinvestment of dividends and distributions. For certain periods, the Fund’s performance reflects the effect of expense waivers. Without the effect of these expense waivers, the performance shown would have been lower.

The Fund’s past performance (before and after taxes) does not necessarily indicate how it will perform in the future. Updated performance information is available at janus.com/advisor/mutual-funds or by calling 1-877-335-2687.

Annual Total Returns for Class I Shares (calendar year-end)

Best Quarter:  First Quarter 2012  11.14%          Worst Quarter:  Second Quarter 2012  −4.75%

The Fund’s year-to-date return as of the calendar quarter ended September 30, 2013 was 15.57%.

Average Annual Total Returns (periods ended 12/31/12)

Average Annual Total Returns Perkins Select Value Fund Class A, C, S, I, N, T Shares	Column	Label		1 Year	Since Inception	Inception Date
Class I Return Before Taxes	Class I Shares	Return Before Taxes		12.48%	14.39%	Dec. 15, 2011
Class I Return After Taxes on Distributions	Class I Shares	Return After Taxes on Distributions		9.75%	11.73%	Dec. 15, 2011
Class I Return After Taxes on Distributions and Sale of Fund Shares	Class I Shares	Return After Taxes on Distributions and Sale of Fund Shares		8.30%	10.79%	Dec. 15, 2011
Class A Return Before Taxes	Class A Shares	Return Before Taxes	[1]	5.80%	7.75%	Dec. 15, 2011
Class C Return Before Taxes	Class C Shares	Return Before Taxes	[2]	10.34%	13.21%	Dec. 15, 2011
Class S Return Before Taxes	Class S Shares	Return Before Taxes		11.89%	13.71%	Dec. 15, 2011
Class N Return Before Taxes	Class N Shares	Return Before Taxes		11.78%	13.68%	Dec. 15, 2011
Class T Return Before Taxes	Class T Shares	Return Before Taxes		12.32%	14.13%	Dec. 15, 2011
Russell 3000® Value Index (reflects no deduction for expenses, fees, or taxes)		Russell 3000® Value Index		17.55%	21.33%	Dec. 15, 2011

The Russell 3000^® Value Index measures the performance of those Russell 3000^® companies with lower price-to-book ratios and lower forecasted growth values. The stocks in the Russell 3000^® Value Index are also members of either the Russell 1000^® Value Index or the Russell 2000^® Value Index. This index is used to calculate the performance fee adjustment.

After-tax returns are calculated using the historically highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes. Actual after-tax returns depend on your individual tax situation and may differ from those shown in the preceding table. The after-tax return information shown above does not apply to Fund shares held through a tax-deferred account, such as a 401(k) plan or an IRA.

After-tax returns are only shown for Class I Shares of the Fund. After-tax returns for the other classes of Shares will vary from those shown for Class I Shares due to varying sales charges (as applicable), fees, and expenses among the classes.

[1] Other Expenses for Class N Shares are based on the estimated annualized expenses that the Shares expect to incur.

[2] Janus Capital has contractually agreed to waive its investment advisory fee and/or reimburse Fund expenses to the extent that the Fund’s total annual fund operating expenses (excluding any performance adjustments to management fees, the distribution and shareholder servicing fees – applicable to Class A Shares, Class C Shares, and Class S Shares; administrative services fees payable pursuant to the Transfer Agency Agreement; brokerage commissions; interest; dividends; taxes; acquired fund fees and expenses; and extraordinary expenses) exceed 0.77% until at least November 1, 2014. The contractual waiver may be terminated or modified prior to this date only at the discretion of the Board of Trustees.

[1] Calculated assuming maximum permitted sales loads.

[2] The one year return is calculated to include the contingent deferred sales charge.

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Perkins Value Plus Income Fund | Class A, C, S, I, N, T Shares

FUND SUMMARY

Perkins Value Plus Income Fund

INVESTMENT OBJECTIVE

Perkins Value Plus Income Fund seeks capital appreciation and current income.

FEES AND EXPENSES OF THE FUND

This table describes the fees and expenses that you may pay if you buy and hold Shares of the Fund. Each share class has different expenses, but represents an investment in the same Fund.

For Class A Shares, you may qualify for sales charge discounts if you and your family invest, or agree to invest in the future, at least $50,000 in the Fund or in other Janus mutual funds. More information about these and other discounts, as well as eligibility requirements for each share class, is available from your financial professional and in the “Purchases” section on page 66 of the Fund’s Prospectus and in the “Purchases” section on page 70 of the Fund’s Statement of Additional Information.

SHAREHOLDER FEES
(fees paid directly from your investment)

Shareholder Fees Perkins Value Plus Income Fund Class A, C, S, I, N, T Shares	Class A	Class C	Class S	Class I	Class N	Class T
Shareholder Fees Column [Text]	Class A	Class C	Class S	Class I	Class N	Class T
Maximum Sales Charge (load) Imposed on Purchases (as a percentage of offering price)	5.75%	none	none	none	none	none
Maximum Deferred Sales Charge (load) (as a percentage of the lower of original purchase price or redemption proceeds)	none	1.00%	none	none	none	none

ANNUAL FUND OPERATING EXPENSES
(expenses that you pay each year as a percentage of the value of your investment)

Annual Fund Operating Expenses Perkins Value Plus Income Fund Class A, C, S, I, N, T Shares		Class A	Class C	Class S	Class I	Class N		Class T
Operating Expenses Column [Text]		Class A	Class C	Class S	Class I	Class N		Class T
Management Fees		0.60%	0.60%	0.60%	0.60%	0.60%		0.60%
Distribution/Service (12b-1) Fees		0.25%	1.00%	0.25%	none	none		none
Other Expenses		0.51%	0.53%	0.74%	0.50%	0.50%	[1]	0.73%
Total Annual Fund Operating Expenses	[2]	1.36%	2.13%	1.59%	1.10%	1.10%		1.33%
Fee Waiver	[2]	0.41%	0.44%	0.41%	0.42%	0.42%		0.40%
Total Annual Fund Operating Expenses After Fee Waiver	[2]	0.95%	1.69%	1.18%	0.68%	0.68%		0.93%

EXAMPLE:

The following Example is based on expenses without waivers. The Example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds.

The Example assumes that you invest $10,000 in the Fund for the time periods indicated and reinvest all dividends and distributions. The Example also assumes that your investment has a 5% return each year and that the Fund’s operating expenses without waivers or recoupments (if applicable) remain the same. Although your actual costs may be higher or lower, based on these assumptions your costs would be:

If Shares are redeemed:

Expense Example Perkins Value Plus Income Fund Class A, C, S, I, N, T Shares (USD $)	Expense Example, By Year, Column [Text]	1 Year	3 Years	5 Years	10 Years
Class A	Class A Shares	706	981	1,277	2,116
Class C	Class C Shares	316	667	1,144	2,462
Class S	Class S Shares	162	502	866	1,889
Class I	Class I Shares	112	350	606	1,340
Class N	Class N Shares	112	350	606	1,340
Class T	Class T Shares	135	421	729	1,601

If Shares are not redeemed:

Expense Example, No Redemption Perkins Value Plus Income Fund Class A, C, S, I, N, T Shares (USD $)	Expense Example, No Redemption, By Year, Column [Text]	1 Year	3 Years	5 Years	10 Years
Class A	Class A Shares	706	981	1,277	2,116
Class C	Class C Shares	216	667	1,144	2,462
Class S	Class S Shares	162	502	866	1,889
Class I	Class I Shares	112	350	606	1,340
Class N	Class N Shares	112	350	606	1,340
Class T	Class T Shares	135	421	729	1,601

Portfolio Turnover:

The Fund pays transaction costs, such as commissions, when it buys and sells securities (or “turns over” its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when Fund shares are held in a taxable account. These costs, which are not reflected in annual fund operating expenses or in the Example, affect the Fund’s performance. During the most recent fiscal year, the Fund’s portfolio turnover rate was 97% of the average value of its portfolio.

PRINCIPAL INVESTMENT STRATEGIES

The Fund pursues its investment objective by normally investing 40-60% of its assets in equity securities selected primarily for capital appreciation and investing the remainder in fixed-income securities and cash equivalents.

Equity Securities. The Fund’s equity investments generate total return from a combination of capital appreciation and, to a lesser degree, current income. Such equity investments may include companies of any size, but the Fund will invest primarily in large- and mid-sized companies whose stock prices the portfolio managers believe to be undervalued or have the potential for high relative dividend yields, or both. The Fund’s equity portfolio managers invest in companies which have fallen out of favor with the market or that appear to be temporarily misunderstood by the investment community. The Fund’s equity portfolio managers generally look for companies with:

• strong balance sheets and solid recurring free cash flows
• attractive relative and absolute valuation ratios or that have underperformed recently
• favorable reward to risk characteristics

Fixed-Income Securities. The Fund’s fixed-income investments generate total return from a combination of current income and capital appreciation, but income is usually the dominant portion. The Fund normally invests the portion of its assets allocated to fixed-income investments in debt securities (including, but not limited to, government bonds, corporate bonds, mortgage-backed securities, asset-backed securities, zero-coupon bonds, and bank loans), convertible securities, and short-term securities. The Fund invests at least 50% of the fixed-income portion of its assets in investment grade debt securities. The Fund will limit its investment in high-yield/high-risk bonds, also known as “junk” bonds, to 50% or less of the fixed-income portion of its net assets.

In addition to considering economic factors such as the effect of interest rates on the Fund’s fixed-income investments, the Fund’s fixed-income portfolio managers apply a “bottom up” approach in choosing investments. This means that the portfolio managers look at income-producing securities one at a time to determine if a security is an attractive investment opportunity and if it is consistent with the Fund’s investment policies.

The Fund may also invest in foreign equity and debt securities, which may include investments in emerging markets.

The Fund may also invest its assets in derivatives, which are instruments that have a value derived from, or directly linked to, an underlying asset, such as equity securities, fixed-income securities, commodities, currencies, interest rates, or market indices. The Fund has and is expected to continue to buy and sell put and call options to enhance returns. The Fund’s exposure to derivatives will vary, is not limited to those derivatives listed, and could be significant at times.

Janus Capital is primarily responsible for the overall asset allocation of the Fund and manages the Fund’s fixed-income investments. Cash positions are considered a part of the Fund’s fixed-income allocation and will be managed by the Fund’s fixed-income portfolio managers. Perkins manages the Fund’s equity investments and assists the adviser in determining the Fund’s overall asset allocation. The Fund may periodically adjust its mix of equity and fixed-income investments in response to changing economic and market conditions, including outside the range of 40-60% of its assets in equity securities. Due to the nature of the fixed-income securities in which the Fund invests, it may have relatively high portfolio turnover compared to other funds.

The Fund’s fixed-income portfolio managers may lend portfolio securities on a short-term or long-term basis, in an amount equal to up to 1/3 of its total assets as determined at the time of the loan origination.

PRINCIPAL INVESTMENT RISKS

The biggest risk is that the Fund’s returns and yields will vary, and you could lose money. The Fund is designed for long-term investors seeking a portfolio including common stocks and bonds selected for their potential to produce capital appreciation and current income. Common stocks tend to be more volatile than many other investment choices.

Market Risk. The value of the Fund’s portfolio may decrease if the value of an individual company or security, or multiple companies or securities, in the portfolio decreases or if the portfolio managers’ belief about a company’s intrinsic worth is incorrect. Further, regardless of how well individual companies or securities perform, the value of the Fund’s portfolio could also decrease if there are deteriorating economic or market conditions. It is important to understand that the value of your investment may fall, sometimes sharply, in response to changes in the market, and you could lose money.

Value Investing Risk. Because different types of stocks tend to shift in and out of favor depending on market and economic conditions, “value” stocks may perform differently than other types of stocks and from the market as a whole, and can continue to be undervalued by the market for long periods of time. It is also possible that a value stock will never appreciate to the extent expected by the equity portfolio managers.

Mid-Sized Companies Risk. The Fund’s investments in securities issued by mid-sized companies may involve greater risks than are customarily associated with larger, more established companies. Securities issued by mid-sized companies tend to be more volatile than securities issued by larger or more established companies and may underperform as compared to the securities of larger companies.

Fixed-Income Securities Risk. The Fund invests in a variety of fixed-income securities. Typically, the values of fixed-income securities change inversely with prevailing interest rates. Therefore, a fundamental risk of fixed-income securities is interest rate risk, which is the risk that the value of such securities will generally decline as prevailing interest rates rise, which may cause the Fund’s net asset value to likewise decrease. How specific fixed-income securities may react to changes in interest rates will depend on the specific characteristics of each security. Fixed-income securities are also subject to credit risk, prepayment risk, valuation risk, and liquidity risk. Credit risk is the risk that the credit strength of an issuer of a fixed-income security will weaken and/or that the issuer will be unable to make timely principal and interest payments and that the security may go into default. Prepayment risk is the risk that during periods of falling interest rates, certain fixed-income securities with higher interest rates, such as mortgage- and asset-backed securities, may be prepaid by their issuers thereby reducing the amount of interest payments. Valuation risk is the risk that one or more of the fixed-income securities in which the Fund invests are priced differently than the value realized upon such security’s sale. In times of market instability, valuation may be more difficult. Liquidity risk is the risk that fixed-income securities may be difficult or impossible to sell at the time that the portfolio managers would like or at the price the portfolio managers believe the security is currently worth.

Mortgage-Backed Securities Risk. Mortgage-backed securities are classified generally as either commercial mortgage-backed securities or residential mortgage-backed securities, each of which is subject to certain specific risks. Mortgage-backed securities tend to be more sensitive to changes in interest rates than other types of debt securities. Investments in mortgage-backed securities are subject to both extension risk, where borrowers extend the duration of their mortgages in times of rising interest rates, and prepayment risk, where borrowers pay off their mortgages sooner than expected in times of declining interest rates. These risks may reduce the Fund’s returns. In addition, investments in mortgage-backed securities, including those comprised of subprime mortgages, may be subject to a higher degree of credit risk, valuation risk, and liquidity risk than various other types of fixed-income securities.

High-Yield/High-Risk Bond Risk. High-yield/high-risk bonds may be more sensitive than other types of bonds to economic changes, political changes, or adverse developments specific to the company that issued the bond, which may adversely affect their value.

Bank Loan Risk. Bank loans are obligations of companies or other entities entered into in connection with recapitalizations, acquisitions, and refinancings. The Fund’s investments in bank loans are generally acquired as a participation interest in, or assignment of, loans originated by a lender or other financial institution. These investments may include institutionally-traded floating and fixed-rate debt securities. Participation interests and assignments involve credit, interest rate, and liquidity risk. In addition, the bank loans underlying these securities often involve borrowers with low credit ratings whose financial conditions are troubled or uncertain, including companies that are highly leveraged or in bankruptcy proceedings.

Foreign Exposure Risk. The Fund may have exposure to foreign markets as a result of its investments in foreign securities, including investments in emerging markets, which can be more volatile than the U.S. markets. As a result, its returns and net asset value may be affected to a large degree by fluctuations in currency exchange rates or political or economic conditions in a particular country. In some foreign markets, there may not be protection against failure by other parties to complete transactions. It may not be possible for the Fund to repatriate capital, dividends, interest, and other income from a particular country or governmental entity. In addition, a market swing in one or more countries or regions where the Fund has invested a significant amount of its assets may have a greater effect on the Fund’s performance than it would in a more geographically diversified portfolio. To the extent the Fund invests in foreign debt securities, such investments are sensitive to changes in interest rates. Additionally, investments in securities of foreign governments involve the risk that a foreign government may not be willing or able to pay interest or repay principal when due. The Fund’s investments in emerging market countries may involve risks greater than, or in addition to, the risks of investing in more developed countries.

Eurozone Risk. A number of countries in the European Union (“EU”) have experienced severe economic and financial difficulties. As a result, financial markets in the EU have been subject to extreme volatility and declines in asset values and liquidity. Responses to these financial problems by European governments, central banks, and others, including austerity measures and reforms, may not work, may result in social unrest, and may limit future growth and economic recovery or have other unintended consequences. Further defaults or restructurings by governments and others of their debt could have additional adverse effects on economies, financial markets, and asset valuations around the world. To the extent that the Fund has exposure to European markets or to transactions tied to the value of the euro, these events could negatively affect the value and liquidity of the Fund’s investments.

Sovereign Debt Risk. The Fund may invest in U.S. and foreign government debt securities (“sovereign debt”). Investments in U.S. sovereign debt are considered low risk. However, investments in non-U.S. sovereign debt can involve a high degree of risk, including the risk that the governmental entity that controls the repayment of sovereign debt may not be willing or able to repay the principal and/or to pay the interest on its sovereign debt in a timely manner. A sovereign debtor’s willingness or ability to satisfy its debt obligation may be affected by various factors including, but not limited to, its cash flow situation, the extent of its foreign currency reserves, the availability of foreign exchange when a payment is due, and the relative size of its debt position in relation to its economy as a whole. In the event of default, there may be limited or no legal remedies for collecting sovereign debt and there may be no bankruptcy proceedings through which the Fund may collect all or part of the sovereign debt that a governmental entity has not repaid.

Real Estate Securities Risk. The Fund’s performance may be affected by the risks associated with investments in real estate-related companies. The value of real estate-related companies’ securities is sensitive to changes in real estate values and rental income, property taxes, interest rates, tax and regulatory requirements, supply and demand, and the management skill and creditworthiness of the company. Investments in real estate investment trusts (“REITs”) involve the same risks as other real estate investments. In addition, a REIT could fail to qualify for tax-free pass-through of its income under the Internal Revenue Code or fail to maintain its exemption from registration under the Investment Company Act of 1940, as amended, which could produce adverse economic consequences for the REIT and its investors, including the Fund.

Derivatives Risk. Derivatives can be highly volatile and involve risks in addition to the risks of the underlying referenced securities. Gains or losses from a derivative investment can be substantially greater than the derivative’s original cost, and can therefore involve leverage. Leverage may cause the Fund to be more volatile than if it had not used leverage. Derivatives can be complex instruments and may involve analysis that differs from that required for other investment types used by the Fund. If the value of a derivative does not correlate well with the particular market or other asset class to which the derivative is intended to provide exposure, the derivative may not produce the anticipated result. Derivatives can also reduce the opportunity for gain or result in losses by offsetting positive returns in other investments. Derivatives can be less liquid than other types of investments and entail the risk that the counterparty will default on its payment obligations. If the counterparty to a derivative transaction defaults, the Fund would risk the loss of the net amount of the payments that it contractually is entitled to receive. To the extent the Fund enters into short derivative positions, the Fund may be exposed to risks similar to those associated with short sales, including the risk that the Fund’s losses are theoretically unlimited.

Allocation Risk. The Fund’s ability to achieve its investment objective depends largely upon the allocation of assets among the equity and fixed asset categories. You could lose money on your investment in the Fund as a result of these allocations. Portfolio management may favor an asset category that underperforms relative to other asset categories. For example, the Fund may be overweighted in equity securities when the stock market is falling and the fixed-income market is rising. Additionally, periodic rebalancing of Fund assets among asset categories may result in increased transaction costs, which may have a negative effect on the Fund’s performance.

Portfolio Turnover Risk. Increased portfolio turnover may result in higher costs, which may have a negative effect on the Fund’s performance. In addition, higher portfolio turnover may result in the acceleration of capital gains and the recognition of greater levels of short-term capital gains, which are taxed at ordinary federal income tax rates when distributed to shareholders.

Securities Lending Risk. The Fund’s fixed-income portfolio managers may seek to earn additional income through lending its securities to certain qualified broker-dealers and institutions. There is the risk that when portfolio securities are lent, the securities may not be returned on a timely basis, and the Fund may experience delays and costs in recovering the security or gaining access to the collateral provided to the Fund to collateralize the loan. If the Fund is unable to recover a security on loan, the Fund may use the collateral to purchase replacement securities in the market. There is a risk that the value of the collateral could decrease below the cost of the replacement security by the time the replacement investment is made, resulting in a loss to the Fund.

An investment in the Fund is not a bank deposit and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency.

PERFORMANCE INFORMATION

The following information provides some indication of the risks of investing in the Fund by showing how the Fund’s performance has varied over time. Class A Shares, Class C Shares, Class S Shares, Class I Shares, and Class T Shares of the Fund commenced operations with the Fund’s inception.

• The performance shown for Class A Shares, Class C Shares, Class S Shares, Class I Shares, and Class T Shares is calculated using the fees and expenses of each respective share class, net of any applicable fee and expense limitations or waivers.
• The performance shown for Class N Shares reflects the performance of the Fund’s Class I Shares, calculated using the fees and expenses of Class N Shares, without the effect of any fee and expense limitations or waivers. If Class N Shares of the Fund had been available during the periods shown, the performance may have been different.

The bar chart depicts the change in performance from year to year during the periods indicated. The bar chart figures do not include any applicable sales charges that an investor may pay when they buy or sell Class A Shares or Class C Shares of the Fund. If sales charges were included, the returns would be lower. The table compares the Fund’s average annual returns for the periods indicated to broad-based securities market indices. The indices are not actively managed and are not available for direct investment. All figures assume reinvestment of dividends and distributions. For certain periods, the Fund’s performance reflects the effect of expense waivers. Without the effect of these expense waivers, the performance shown would have been lower.

The Fund’s past performance (before and after taxes) does not necessarily indicate how it will perform in the future. Updated performance information is available at janus.com/advisor/mutual-funds or by calling 1-877-335-2687.

Annual Total Returns for Class I Shares (calendar year-end)

Best Quarter:  Fourth Quarter 2011  7.22%          Worst Quarter:  Third Quarter 2011  −7.73%

The Fund’s year-to-date return as of the calendar quarter ended September 30, 2013 was 9.16%.

Average Annual Total Returns (periods ended 12/31/12)

Average Annual Total Returns Perkins Value Plus Income Fund Class A, C, S, I, N, T Shares	Column	Label		1 Year	Since Inception	Inception Date
Class I Return Before Taxes	Class I Shares	Return Before Taxes		11.75%	10.29%	Jul. 30, 2010
Class I Return After Taxes on Distributions	Class I Shares	Return After Taxes on Distributions		10.31%	8.61%	Jul. 30, 2010
Class I Return After Taxes on Distributions and Sale of Fund Shares	Class I Shares	Return After Taxes on Distributions and Sale of Fund Shares		8.20%	7.99%	Jul. 30, 2010
Class A Return Before Taxes	Class A Shares	Return Before Taxes	[1]	5.05%	7.40%	Jul. 30, 2010
Class C Return Before Taxes	Class C Shares	Return Before Taxes	[2]	9.94%	9.39%	Jul. 30, 2010
Class S Return Before Taxes	Class S Shares	Return Before Taxes		11.25%	9.81%	Jul. 30, 2010
Class N Return Before Taxes	Class N Shares	Return Before Taxes		11.26%	9.82%	Jul. 30, 2010
Class T Return Before Taxes	Class T Shares	Return Before Taxes		11.57%	10.10%	Jul. 30, 2010
Russell 1000® Value Index (reflects no deduction for expenses, fees, or taxes)		Russell 1000® Value Index		17.51%	13.02%	Jul. 30, 2010
Barclays U.S. Aggregate Bond Index (reflects no deduction for expenses, fees, or taxes)		Barclays U.S. Aggregate Bond Index		4.21%	4.97%	Jul. 30, 2010
Value Income Index (reflects no deduction for expenses, fees, or taxes)		Value Income Index		10.84%	9.26%	Jul. 30, 2010

The Value Income Index is an internally-calculated, hypothetical combination of unmanaged indices that combines total returns from the Russell 1000^® Value Index (50%) and the Barclays U.S. Aggregate Bond Index (50%).

After-tax returns are calculated using the historically highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes. Actual after-tax returns depend on your individual tax situation and may differ from those shown in the preceding table. The after-tax return information shown above does not apply to Fund shares held through a tax-deferred account, such as a 401(k) plan or an IRA.

After-tax returns are only shown for Class I Shares of the Fund. After-tax returns for the other classes of Shares will vary from those shown for Class I Shares due to varying sales charges (as applicable), fees, and expenses among the classes.

[1] Other Expenses for Class N Shares are based on the estimated annualized expenses that the Shares expect to incur.

[2] Janus Capital has contractually agreed to waive its investment advisory fee and/or reimburse Fund expenses to the extent that the Fund’s total annual fund operating expenses (excluding the distribution and shareholder servicing fees – applicable to Class A Shares, Class C Shares, and Class S Shares; administrative services fees payable pursuant to the Transfer Agency Agreement; brokerage commissions; interest; dividends; taxes; acquired fund fees and expenses; and extraordinary expenses) exceed 0.68% until at least November 1, 2014. The contractual waiver may be terminated or modified prior to this date only at the discretion of the Board of Trustees. For a period of three years subsequent to the Fund’s commencement of operations (July 30, 2010), Janus Capital may recover from the Fund fees and expenses previously waived or reimbursed, which could then be considered a deferral, if the Fund’s expense ratio, including recovered expenses, falls below the expense limit.

[1] Calculated assuming maximum permitted sales loads.

[2] The one year return is calculated to include the contingent deferred sales charge.

XML

Label	Element	Value
Risk/Return:	rr_RiskReturnAbstract
Registrant Name	dei_EntityRegistrantName	JANUS INVESTMENT FUND
Prospectus Date	rr_ProspectusDate	Oct. 28, 2013
Janus Global Bond Fund | Class D Shares
Risk/Return:	rr_RiskReturnAbstract
Risk/Return [Heading]	rr_RiskReturnHeading	FUND SUMMARY Janus Global Bond Fund
Objective [Heading]	rr_ObjectiveHeading	INVESTMENT OBJECTIVE
Objective, Primary [Text Block]	rr_ObjectivePrimaryTextBlock	Janus Global Bond Fund seeks total return, consistent with preservation of capital.
Expense [Heading]	rr_ExpenseHeading	FEES AND EXPENSES OF THE FUND
Expense Narrative [Text Block]	rr_ExpenseNarrativeTextBlock	This table describes the fees and expenses that you may pay if you buy and hold Shares of the Fund.
Operating Expenses Caption [Text]	rr_OperatingExpensesCaption	ANNUAL FUND OPERATING EXPENSES (expenses that you pay each year as a percentage of the value of your investment)
Fee Waiver or Reimbursement over Assets, Date of Termination	rr_FeeWaiverOrReimbursementOverAssetsDateOfTermination	November 1, 2014
Portfolio Turnover [Heading]	rr_PortfolioTurnoverHeading	Portfolio Turnover:
Portfolio Turnover [Text Block]	rr_PortfolioTurnoverTextBlock	The Fund pays transaction costs, such as commissions, when it buys and sells securities (or “turns over” its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when Fund shares are held in a taxable account. These costs, which are not reflected in annual fund operating expenses or in the Example, affect the Fund’s performance. During the most recent fiscal year, the Fund’s portfolio turnover rate was 182% of the average value of its portfolio.
Portfolio Turnover, Rate	rr_PortfolioTurnoverRate	182.00%
Expense Example [Heading]	rr_ExpenseExampleHeading	EXAMPLE:
Expense Example by Year [Heading]	rr_ExpenseExampleByYearHeading	The Example assumes that you invest $10,000 in the Fund for the time periods indicated, reinvest all dividends and distributions, and then redeem all of your Shares at the end of each period. The Example also assumes that your investment has a 5% return each year and that the Fund’s operating expenses without waivers or recoupments (if applicable) remain the same. Although your actual costs may be higher or lower, based on these assumptions your costs would be:
Expense Example Narrative [Text Block]	rr_ExpenseExampleNarrativeTextBlock	The following Example is based on expenses without waivers. The Example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds.
Strategy [Heading]	rr_StrategyHeading	PRINCIPAL INVESTMENT STRATEGIES
Strategy Narrative [Text Block]	rr_StrategyNarrativeTextBlock	The Fund pursues its investment objective by investing, under normal circumstances, at least 80% of its net assets in bonds. Bonds include, but are not limited to, corporate bonds, government notes and bonds, convertible bonds, mortgage-backed securities, and zero-coupon bonds. The Fund invests in corporate debt securities of issuers in a number of different countries, which may include the United States. The Fund invests in securities of issuers that are economically tied to developed and emerging market countries. The Fund may invest across all fixed-income sectors, including U.S. and non-U.S. government securities. The Fund’s investments may be denominated in local currency or U.S. dollar-denominated. The Fund may invest in debt securities with a range of maturities from short- to long-term. The Fund may invest up to 35% of its net assets in high-yield/high-risk debt securities. The Fund may also invest in preferred and common stock, money market instruments, municipal bonds, commercial and residential mortgage-backed securities, asset-backed securities, other securitized and structured debt products, private placements, and other investment companies, including exchange-traded funds (“ETFs”). The Fund may also invest in bank loans, euro-denominated obligations, buy backs or dollar rolls, when-issued securities, and reverse repurchase agreements. Due to the nature of securities in which the Fund invests, it may have relatively high portfolio turnover compared to other funds. In addition, the Fund may invest its assets in derivatives, which are instruments that have a value derived from, or directly linked to, an underlying asset, such as equity securities, fixed-income securities, commodities, currencies, interest rates, or market indices, as substitutes for securities in which the Fund invests. The Fund has invested in and is expected to continue to invest in collateralized forward foreign currency exchange contracts, futures, options, and swaps (including interest rate swaps, total return swaps, and credit default swaps) for hedging purposes (to offset risks associated with an investment, currency exposure, or market conditions) and to increase or decrease the Fund’s exposure to a particular market, to manage or adjust the risk profile of the Fund related to an investment or currency exposure, to adjust its currency exposure relative to its benchmark index, and to earn income and enhance returns. In particular, the Fund may use interest rate futures to manage portfolio risk. The Fund’s exposure to derivatives will vary, is not limited to those derivatives listed, and could be significant at times. For purposes of meeting its 80% investment policy, the Fund may include derivatives that have characteristics similar to the securities in which the Fund may directly invest. In addition to considering economic factors such as the effect of interest rates on the Fund’s investments, the portfolio managers apply a “bottom up” approach in choosing investments. This means that the portfolio managers look at income-producing securities one at a time to determine if a security is an attractive investment opportunity and if it is consistent with the Fund’s investment policies. The Fund may lend portfolio securities on a short-term or long-term basis, in an amount equal to up to 1/3 of its total assets as determined at the time of the loan origination.
Risk [Heading]	rr_RiskHeading	PRINCIPAL INVESTMENT RISKS
Risk Narrative [Text Block]	rr_RiskNarrativeTextBlock	Although the Fund may be less volatile than funds that invest most of their assets in common stocks, the Fund’s returns and yields will vary, and you could lose money. Fixed-Income Securities Risk. The Fund invests in a variety of fixed-income securities. Typically, the values of fixed-income securities change inversely with prevailing interest rates. Therefore, a fundamental risk of fixed-income securities is interest rate risk, which is the risk that the value of such securities will generally decline as prevailing interest rates rise, which may cause the Fund’s net asset value to likewise decrease. How specific fixed-income securities may react to changes in interest rates will depend on the specific characteristics of each security. Fixed-income securities are also subject to credit risk, prepayment risk, valuation risk, and liquidity risk. Credit risk is the risk that the credit strength of an issuer of a fixed-income security will weaken and/or that the issuer will be unable to make timely principal and interest payments and that the security may go into default. Prepayment risk is the risk that during periods of falling interest rates, certain fixed-income securities with higher interest rates, such as mortgage- and asset-backed securities, may be prepaid by their issuers thereby reducing the amount of interest payments. Valuation risk is the risk that one or more of the fixed-income securities in which the Fund invests are priced differently than the value realized upon such security’s sale. In times of market instability, valuation may be more difficult. Liquidity risk is the risk that fixed-income securities may be difficult or impossible to sell at the time that the portfolio managers would like or at the price the portfolio managers believe the security is currently worth. Foreign Exposure Risk. The Fund normally has significant exposure to foreign markets as a result of its investments in foreign securities, including investments in emerging markets, which can be more volatile than the U.S. markets. As a result, its returns and net asset value may be affected to a large degree by fluctuations in currency exchange rates or political or economic conditions in a particular country. In some foreign markets, there may not be protection against failure by other parties to complete transactions. It may not be possible for the Fund to repatriate capital, dividends, interest, and other income from a particular country or governmental entity. In addition, a market swing in one or more countries or regions where the Fund has invested a significant amount of its assets may have a greater effect on the Fund’s performance than it would in a more geographically diversified portfolio. The Fund’s investments in emerging market countries may involve risks greater than, or in addition to, the risks of investing in more developed countries. To the extent the Fund invests in foreign debt securities, such investments are sensitive to changes in interest rates. Additionally, investments in securities of foreign governments involve the risk that a foreign government may not be willing or able to pay interest or repay principal when due. Eurozone Risk. A number of countries in the European Union (“EU”) have experienced severe economic and financial difficulties. As a result, financial markets in the EU have been subject to extreme volatility and declines in asset values and liquidity. Responses to these financial problems by European governments, central banks, and others, including austerity measures and reforms, may not work, may result in social unrest, and may limit future growth and economic recovery or have other unintended consequences. Further defaults or restructurings by governments and others of their debt could have additional adverse effects on economies, financial markets, and asset valuations around the world. To the extent that the Fund has exposure to European markets or to transactions tied to the value of the euro, these events could negatively affect the value and liquidity of the Fund’s investments. Emerging Markets Risk. The risks of foreign investing mentioned above are heightened when investing in emerging markets. Emerging markets securities involve a number of additional risks, which may result from less government supervision and regulation of business and industry practices (including the potential lack of strict finance and accounting controls and standards), stock exchanges, brokers, and listed companies, making these investments potentially more volatile in price and less liquid than investments in developed securities markets, resulting in greater risk to investors. There is a risk in developing countries that a future economic or political crisis could lead to price controls, forced mergers of companies, expropriation or confiscatory taxation, imposition or enforcement of foreign ownership limits, seizure, nationalization, or creation of government monopolies, any of which may have a detrimental effect on the Fund’s investments. In addition, the Fund’s investments may be denominated in foreign currencies and therefore, changes in the value of a country’s currency compared to the U.S. dollar may affect the value of the Fund’s investments. To the extent that the Fund invests a significant portion of its assets in the securities of issuers in or companies of a single country or region, it is more likely to be impacted by events or conditions affecting that country or region, which could have a negative impact on the Fund’s performance. Some of the risks of investing directly in foreign and emerging market securities may be reduced when the Fund invests indirectly in foreign securities through various other investment vehicles including derivatives, which also involve other risks. As of June 30, 2013, approximately 4.2% of the Fund’s investments were in emerging markets. Mortgage-Backed Securities Risk. Mortgage-backed securities are classified generally as either commercial mortgage-backed securities or residential mortgage-backed securities, each of which is subject to certain specific risks. Mortgage-backed securities tend to be more sensitive to changes in interest rates than other types of debt securities. Investments in mortgage-backed securities are subject to both extension risk, where borrowers extend the duration of their mortgages in times of rising interest rates, and prepayment risk, where borrowers pay off their mortgages sooner than expected in times of declining interest rates. These risks may reduce the Fund’s returns. In addition, investments in mortgage-backed securities, including those comprised of subprime mortgages, may be subject to a higher degree of credit risk, valuation risk, and liquidity risk than various other types of fixed-income securities. Sovereign Debt Risk. The Fund may invest in U.S. and foreign government debt securities (“sovereign debt”). Investments in U.S. sovereign debt are considered low risk. However, investments in non-U.S. sovereign debt can involve a high degree of risk, including the risk that the governmental entity that controls the repayment of sovereign debt may not be willing or able to repay the principal and/or to pay the interest on its sovereign debt in a timely manner. A sovereign debtor’s willingness or ability to satisfy its debt obligation may be affected by various factors including, but not limited to, its cash flow situation, the extent of its foreign currency reserves, the availability of foreign exchange when a payment is due, and the relative size of its debt position in relation to its economy as a whole. In the event of default, there may be limited or no legal remedies for collecting sovereign debt and there may be no bankruptcy proceedings through which the Fund may collect all or part of the sovereign debt that a governmental entity has not repaid. High-Yield/High-Risk Bond Risk. High-yield/high-risk bonds (also known as “junk” bonds) may be more sensitive than other types of bonds to economic changes, political changes, or adverse developments specific to the company that issued the bond, which may adversely affect their value. Bank Loan Risk. Bank loans are obligations of companies or other entities entered into in connection with recapitalizations, acquisitions, and refinancings. The Fund’s investments in bank loans are generally acquired as a participation interest in, or assignment of, loans originated by a lender or other financial institution. These investments may include institutionally-traded floating and fixed-rate debt securities. Participation interests and assignments involve credit, interest rate, and liquidity risk. In addition, the bank loans underlying these securities often involve borrowers with low credit ratings whose financial conditions are troubled or uncertain, including companies that are highly leveraged or in bankruptcy proceedings. Exchange-Traded Funds Risk. The Fund may purchase shares of exchange-traded funds (“ETFs”) to gain exposure to a particular portion of the market. ETFs are pooled investment vehicles, which may be managed or unmanaged, that generally seek to track the performance of a specific index. ETFs are traded on an exchange at market prices that may vary from the net asset value of their underlying investments. When the Fund invests in an ETF, in addition to directly bearing the expenses associated with its own operations, it will bear a pro rata portion of the ETF’s expenses. ETFs have certain inherent risks generally associated with investments in a portfolio of securities in which the ETF is invested, including the risk that the general level of stock prices may decline, thereby adversely affecting the value of each unit of the ETF. ETFs also involve the risk that an active trading market for an ETF’s shares may not develop or be maintained. Derivatives Risk. Derivatives can be highly volatile and involve risks in addition to the risks of the underlying referenced securities. Gains or losses from a derivative investment can be substantially greater than the derivative’s original cost, and can therefore involve leverage. Leverage may cause the Fund to be more volatile than if it had not used leverage. Derivatives can be complex instruments and may involve analysis that differs from that required for other investment types used by the Fund. If the value of a derivative does not correlate well with the particular market or other asset class to which the derivative is intended to provide exposure, the derivative may not produce the anticipated result. Derivatives can also reduce the opportunity for gain or result in losses by offsetting positive returns in other investments. Derivatives can be less liquid than other types of investments and entail the risk that the counterparty will default on its payment obligations. If the counterparty to a derivative transaction defaults, the Fund would risk the loss of the net amount of the payments that it contractually is entitled to receive. To the extent the Fund enters into short derivative positions, the Fund may be exposed to risks similar to those associated with short sales, including the risk that the Fund’s losses are theoretically unlimited. Portfolio Turnover Risk. Increased portfolio turnover may result in higher costs, which may have a negative effect on the Fund’s performance. In addition, higher portfolio turnover may result in the acceleration of capital gains and the recognition of greater levels of short-term capital gains, which are taxed at ordinary federal income tax rates when distributed to shareholders. Securities Lending Risk. The Fund may seek to earn additional income through lending its securities to certain qualified broker-dealers and institutions. There is the risk that when portfolio securities are lent, the securities may not be returned on a timely basis, and the Fund may experience delays and costs in recovering the security or gaining access to the collateral provided to the Fund to collateralize the loan. If the Fund is unable to recover a security on loan, the Fund may use the collateral to purchase replacement securities in the market. There is a risk that the value of the collateral could decrease below the cost of the replacement security by the time the replacement investment is made, resulting in a loss to the Fund. An investment in the Fund is not a bank deposit and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency.
Risk Lose Money [Text]	rr_RiskLoseMoney	Although the Fund may be less volatile than funds that invest most of their assets in common stocks, the Fund’s returns and yields will vary, and you could lose money.
Risk Not Insured Depository Institution [Text]	rr_RiskNotInsuredDepositoryInstitution	An investment in the Fund is not a bank deposit and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency.
Bar Chart and Performance Table [Heading]	rr_BarChartAndPerformanceTableHeading	PERFORMANCE INFORMATION
Performance Narrative [Text Block]	rr_PerformanceNarrativeTextBlock	The following information provides some indication of the risks of investing in the Fund by showing how the Fund’s performance has varied over time. The bar chart depicts the change in performance from year to year during the periods indicated. The table compares the Fund’s average annual returns for the periods indicated to broad-based securities market indices. The indices are not actively managed and are not available for direct investment. All figures assume reinvestment of dividends and distributions. For certain periods, the Fund’s performance reflects the effect of expense waivers. Without the effect of these expense waivers, the performance shown would have been lower. The Fund’s past performance (before and after taxes) does not necessarily indicate how it will perform in the future. Updated performance information is available at janus.com/allfunds or by calling 1-800-525-3713.
Performance Information Illustrates Variability of Returns [Text]	rr_PerformanceInformationIllustratesVariabilityOfReturns	The following information provides some indication of the risks of investing in the Fund by showing how the Fund’s performance has varied over time. The bar chart depicts the change in performance from year to year during the periods indicated.
Performance Additional Market Index [Text]	rr_PerformanceAdditionalMarketIndex	The table compares the Fund’s average annual returns for the periods indicated to broad-based securities market indices. The indices are not actively managed and are not available for direct investment. All figures assume reinvestment of dividends and distributions.
Performance Availability Phone [Text]	rr_PerformanceAvailabilityPhone	1-800-525-3713
Performance Availability Website Address [Text]	rr_PerformanceAvailabilityWebSiteAddress	janus.com/allfunds
Performance Past Does Not Indicate Future [Text]	rr_PerformancePastDoesNotIndicateFuture	The Fund’s past performance (before and after taxes) does not necessarily indicate how it will perform in the future.
Bar Chart [Heading]	rr_BarChartHeading	Annual Total Returns for Class D Shares (calendar year-end)
Bar Chart Closing [Text Block]	rr_BarChartClosingTextBlock	Best Quarter:  Third Quarter 2012  4.33%          Worst Quarter:  Fourth Quarter 2012  0.18%
Year to Date Return, Label	rr_YearToDateReturnLabel	The Fund’s year-to-date return as of the calendar quarter ended September 30, 2013 was −3.24%.
Performance Table Heading	rr_PerformanceTableHeading	Average Annual Total Returns (periods ended 12/31/12)
Performance Table Uses Highest Federal Rate	rr_PerformanceTableUsesHighestFederalRate	After-tax returns are calculated using the historically highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes.
Performance Table Not Relevant to Tax Deferred	rr_PerformanceTableNotRelevantToTaxDeferred	Actual after-tax returns depend on your individual tax situation and may differ from those shown in the preceding table. The after-tax return information shown above does not apply to Fund shares held through a tax-deferred account, such as a 401(k) plan or an IRA.
Performance Table Narrative	rr_PerformanceTableNarrativeTextBlock	After-tax returns are calculated using the historically highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes. Actual after-tax returns depend on your individual tax situation and may differ from those shown in the preceding table. The after-tax return information shown above does not apply to Fund shares held through a tax-deferred account, such as a 401(k) plan or an IRA.
Performance Table Closing [Text Block]	rr_PerformanceTableClosingTextBlock	Updated performance information is available at janus.com/allfunds or by calling 1-800-525-3713.
Janus Global Bond Fund | Class D Shares | Class D
Risk/Return:	rr_RiskReturnAbstract
Operating Expenses Column [Text]	rr_OperatingExpensesColumnName	Class D
Management Fees	rr_ManagementFeesOverAssets	0.60%
Other Expenses	rr_OtherExpensesOverAssets	0.38%	[1]
Total Annual Fund Operating Expenses	rr_ExpensesOverAssets	0.98%	[2]
Fee Waiver	rr_FeeWaiverOrReimbursementOverAssets	0.10%	[2]
Total Annual Fund Operating Expenses After Fee Waiver	rr_NetExpensesOverAssets	0.88%	[2]
Expense Example, By Year, Column [Text]	rr_ExpenseExampleByYearColumnName	Class D Shares
1 Year	rr_ExpenseExampleYear01	$ 100
3 Years	rr_ExpenseExampleYear03	312
5 Years	rr_ExpenseExampleYear05	542
10 Years	rr_ExpenseExampleYear10	$ 1,201
2011	rr_AnnualReturn2011	6.65%
2012	rr_AnnualReturn2012	8.01%
Bar Chart, Year to Date Return, Date	rr_BarChartYearToDateReturnDate	Sep. 30, 2013
Bar Chart, Year to Date Return	rr_BarChartYearToDateReturn	(3.24%)
Highest Quarterly Return, Label	rr_HighestQuarterlyReturnLabel	Best Quarter:
Highest Quarterly Return, Date	rr_BarChartHighestQuarterlyReturnDate	Sep. 30, 2012
Highest Quarterly Return	rr_BarChartHighestQuarterlyReturn	4.33%
Lowest Quarterly Return, Label	rr_LowestQuarterlyReturnLabel	Worst Quarter:
Lowest Quarterly Return, Date	rr_BarChartLowestQuarterlyReturnDate	Dec. 31, 2012
Lowest Quarterly Return	rr_BarChartLowestQuarterlyReturn	0.18%
Janus Global Bond Fund | Class D Shares | Return Before Taxes | Class D
Risk/Return:	rr_RiskReturnAbstract
Column	rr_AverageAnnualReturnColumnName	Class D Shares
Label	rr_AverageAnnualReturnLabel	Return Before Taxes
1 Year	rr_AverageAnnualReturnYear01	8.01%
Since Inception	rr_AverageAnnualReturnSinceInception	7.30%
Inception Date	rr_AverageAnnualReturnInceptionDate	Dec. 28, 2010
Janus Global Bond Fund | Class D Shares | Return After Taxes on Distributions | Class D
Risk/Return:	rr_RiskReturnAbstract
Column	rr_AverageAnnualReturnColumnName	Class D Shares
Label	rr_AverageAnnualReturnLabel	Return After Taxes on Distributions
1 Year	rr_AverageAnnualReturnYear01	6.18%
Since Inception	rr_AverageAnnualReturnSinceInception	5.72%
Inception Date	rr_AverageAnnualReturnInceptionDate	Dec. 28, 2010
Janus Global Bond Fund | Class D Shares | Return After Taxes on Distributions and Sale of Fund Shares | Class D
Risk/Return:	rr_RiskReturnAbstract
Column	rr_AverageAnnualReturnColumnName	Class D Shares
Label	rr_AverageAnnualReturnLabel	Return After Taxes on Distributions and Sale of Fund Shares
1 Year	rr_AverageAnnualReturnYear01	5.33%
Since Inception	rr_AverageAnnualReturnSinceInception	5.34%
Inception Date	rr_AverageAnnualReturnInceptionDate	Dec. 28, 2010
Janus Global Bond Fund | Class D Shares | Barclays Global Aggregate Bond Index (reflects no deduction for expenses, fees, or taxes)
Risk/Return:	rr_RiskReturnAbstract
Label	rr_AverageAnnualReturnLabel	Barclays Global Aggregate Bond Index
1 Year	rr_AverageAnnualReturnYear01	4.32%
Since Inception	rr_AverageAnnualReturnSinceInception	5.74%
Inception Date	rr_AverageAnnualReturnInceptionDate	Dec. 28, 2010
Janus Global Bond Fund | Class D Shares | Barclays Global Aggregate Corporate Bond Index (reflects no deduction for expenses, fees, or taxes)
Risk/Return:	rr_RiskReturnAbstract
Label	rr_AverageAnnualReturnLabel	Barclays Global Aggregate Corporate Bond Index
1 Year	rr_AverageAnnualReturnYear01	11.21%
Since Inception	rr_AverageAnnualReturnSinceInception	8.59%
Inception Date	rr_AverageAnnualReturnInceptionDate	Dec. 28, 2010

[1] Other Expenses are based on the estimated expenses that the Fund expects to incur.

[2] Janus Capital has contractually agreed to waive its investment advisory fee and/or reimburse Fund expenses to the extent that the Fund’s total annual fund operating expenses (excluding administrative services fees payable pursuant to the Transfer Agency Agreement, brokerage commissions, interest, dividends, taxes, acquired fund fees and expenses, and extraordinary expenses) exceed 0.75% until at least November 1, 2014. The contractual waiver may be terminated or modified prior to this date only at the discretion of the Board of Trustees. For a period of three years subsequent to the Fund’s commencement of operations (December 28, 2010) or until the Fund’s assets exceed the first breakpoint in the investment advisory fee schedule, whichever occurs first, Janus Capital may recover from the Fund fees and expenses previously waived or reimbursed, which could then be considered a deferral, if the Fund’s expense ratio, including recovered expenses, falls below the expense limit.

XML

Label	Element	Value
Risk/Return:	rr_RiskReturnAbstract
Document Type	dei_DocumentType	485BPOS
Document Period End Date	dei_DocumentPeriodEndDate	Jun. 30, 2013
Registrant Name	dei_EntityRegistrantName	JANUS INVESTMENT FUND
Central Index Key	dei_EntityCentralIndexKey	0000277751
Amendment Flag	dei_AmendmentFlag	false
Document Creation Date	dei_DocumentCreationDate	Oct. 28, 2013
Document Effective Date	dei_DocumentEffectiveDate	Oct. 28, 2013
Prospectus Date	rr_ProspectusDate	Oct. 28, 2013

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Label	Element	Value
Risk/Return:	rr_RiskReturnAbstract
Registrant Name	dei_EntityRegistrantName	JANUS INVESTMENT FUND
Prospectus Date	rr_ProspectusDate	Oct. 28, 2013
Document Creation Date	dei_DocumentCreationDate	Oct. 28, 2013

XML

Perkins Select Value Fund | Class D Shares

FUND SUMMARY

Perkins Select Value Fund

INVESTMENT OBJECTIVE

Perkins Select Value Fund seeks capital appreciation.

FEES AND EXPENSES OF THE FUND

This table describes the fees and expenses that you may pay if you buy and hold Shares of the Fund.

ANNUAL FUND OPERATING EXPENSES
(expenses that you pay each year as a percentage of the value of your investment)

Annual Fund Operating Expenses		Perkins Select Value Fund Class D Shares Class D
Operating Expenses Column [Text]		Class D
Management Fees (may adjust up or down)		0.63%
Other Expenses		0.38%
Total Annual Fund Operating Expenses	[1]	1.01%
Fee Waiver	[1]	0.19%
Total Annual Fund Operating Expenses After Fee Waiver	[1]	0.82%

EXAMPLE:

The following Example is based on expenses without waivers. The Example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds.

The Example assumes that you invest $10,000 in the Fund for the time periods indicated, reinvest all dividends and distributions, and then redeem all of your Shares at the end of each period. The Example also assumes that your investment has a 5% return each year and that the Fund’s operating expenses without waivers remain the same. Although your actual costs may be higher or lower, based on these assumptions your costs would be:

Expense Example (USD $)	Expense Example, By Year, Column [Text]	1 Year	3 Years	5 Years	10 Years
Perkins Select Value Fund Class D Shares Class D	Class D Shares	103	322	558	1,236

Portfolio Turnover:

The Fund pays transaction costs, such as commissions, when it buys and sells securities (or “turns over” its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when Fund shares are held in a taxable account. These costs, which are not reflected in annual fund operating expenses or in the Example, affect the Fund’s performance. During the most recent fiscal year, the Fund’s portfolio turnover rate was 62% of the average value of its portfolio.

PRINCIPAL INVESTMENT STRATEGIES

The Fund pursues its investment objective by investing primarily in common stocks in all capitalization ranges selected for their capital appreciation potential. The Fund primarily invests in the common stocks of companies of any size whose stock prices the portfolio managers believe to be undervalued. The Fund may also invest in foreign equity and debt securities, which may include investments in emerging markets. In addition, when the portfolio managers believe that market conditions are unfavorable for investing, or when they are otherwise unable to locate attractive investment opportunities, the Fund’s cash or similar investments may increase.

The Fund focuses on companies that have fallen out of favor with the market or that appear to be temporarily misunderstood by the investment community. The Fund’s portfolio managers generally look for companies with:

• strong balance sheets and solid recurring free cash flows
• attractive relative and absolute valuation ratios or that have underperformed recently
• favorable reward to risk characteristics

The Fund may invest its assets in derivatives, which are instruments that have a value derived from, or directly linked to, an underlying asset, such as equity securities, fixed-income securities, commodities, currencies, interest rates, or market indices, as substitutes for securities in which the Fund invests. The Fund may invest in derivative instruments (by taking long and/or short positions) for different purposes, including hedging (to offset risks associated with an investment, currency exposure, or market conditions) and to earn income and enhance returns.

PRINCIPAL INVESTMENT RISKS

The biggest risk is that the Fund’s returns will vary, and you could lose money. The Fund is designed for long-term investors seeking an equity portfolio, including common stocks. Common stocks tend to be more volatile than many other investment choices.

Value Investing Risk. Because different types of stocks tend to shift in and out of favor depending on market and economic conditions, “value” stocks may perform differently than other types of stocks and from the market as a whole, and can continue to be undervalued by the market for long periods of time. It is also possible that a value stock will never appreciate to the extent expected by the portfolio managers. When the Fund’s investments in cash or similar investments increase due to a lack of favorable investment opportunities or other extraordinary factors, the Fund may not participate in market advances or declines to the same extent that it would if the Fund had been fully invested.

Market Risk. The value of the Fund’s portfolio may decrease if the value of an individual company or security, or multiple companies or securities, in the portfolio decreases or if the portfolio managers’ belief about a company’s intrinsic worth is incorrect. Further, regardless of how well individual companies or securities perform, the value of the Fund’s portfolio could also decrease if there are deteriorating economic or market conditions. It is important to understand that the value of your investment may fall, sometimes sharply, in response to changes in the market, and you could lose money.

Foreign Exposure Risk. The Fund may have significant exposure to foreign markets as a result of its investments in foreign securities, including investments in emerging markets, which can be more volatile than the U.S. markets. As a result, its returns and net asset value may be affected to a large degree by fluctuations in currency exchange rates or political or economic conditions in a particular country. In some foreign markets, there may not be protection against failure by other parties to complete transactions. It may not be possible for the Fund to repatriate capital, dividends, interest, and other income from a particular country or governmental entity. In addition, a market swing in one or more countries or regions where the Fund has invested a significant amount of its assets may have a greater effect on the Fund’s performance than it would in a more geographically diversified portfolio. To the extent the Fund invests in foreign debt securities, such investments are sensitive to changes in interest rates. Additionally, investments in securities of foreign governments involve the risk that a foreign government may not be willing or able to pay interest or repay principal when due.

Eurozone Risk. A number of countries in the European Union (“EU”) have experienced severe economic and financial difficulties. As a result, financial markets in the EU have been subject to extreme volatility and declines in asset values and liquidity. Responses to these financial problems by European governments, central banks, and others, including austerity measures and reforms, may not work, may result in social unrest, and may limit future growth and economic recovery or have other unintended consequences. Further defaults or restructurings by governments and others of their debt could have additional adverse effects on economies, financial markets, and asset valuations around the world. To the extent that the Fund has exposure to European markets or to transactions tied to the value of the euro, these events could negatively affect the value and liquidity of the Fund’s investments.

Real Estate Securities Risk. The Fund’s performance may be affected by the risks associated with investments in real estate-related companies. The value of real estate-related companies’ securities is sensitive to changes in real estate values and rental income, property taxes, interest rates, tax and regulatory requirements, supply and demand, and the management skill and creditworthiness of the company. Investments in real estate investment trusts (“REITs”) involve the same risks as other real estate investments. In addition, a REIT could fail to qualify for tax-free pass-through of its income under the Internal Revenue Code or fail to maintain its exemption from registration under the Investment Company Act of 1940, as amended, which could produce adverse economic consequences for the REIT and its investors, including the Fund.

Derivatives Risk. Derivatives can be highly volatile and involve risks in addition to the risks of the underlying referenced securities. Gains or losses from a derivative investment can be substantially greater than the derivative’s original cost, and can therefore involve leverage. Leverage may cause the Fund to be more volatile than if it had not used leverage. Derivatives can be less liquid than other types of investments and entail the risk that the counterparty will default on its payment obligations.

An investment in the Fund is not a bank deposit and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency.

PERFORMANCE INFORMATION

The following information provides some indication of the risks of investing in the Fund by showing how the Fund’s performance has varied over time. The bar chart depicts the Fund’s performance during the period indicated. The table compares the Fund’s average annual returns for the periods indicated to a broad-based securities market index. The index is not actively managed and is not available for direct investment. All figures assume reinvestment of dividends and distributions. For certain periods, the Fund’s performance reflects the effect of expense waivers. Without the effect of these expense waivers, the performance shown would have been lower.

The Fund’s past performance (before and after taxes) does not necessarily indicate how it will perform in the future. Updated performance information is available at janus.com/allfunds or by calling 1-800-525-3713.

Annual Total Returns for Class D Shares (calendar year-end)

Best Quarter:  First Quarter 2012  11.14%          Worst Quarter:  Second Quarter 2012  −4.75%

The Fund’s year-to-date return as of the calendar quarter ended September 30, 2013 was 15.49%.

Average Annual Total Returns (periods ended 12/31/12)

Average Annual Total Returns Perkins Select Value Fund Class D Shares	Column	Label	1 Year	Since Inception	Inception Date
Return Before Taxes	Class D Shares	Return Before Taxes	12.30%	14.22%	Dec. 15, 2011
Return After Taxes on Distributions	Class D Shares	Return After Taxes on Distributions	9.60%	11.58%	Dec. 15, 2011
Return After Taxes on Distributions and Sale of Fund Shares	Class D Shares	Return After Taxes on Distributions and Sale of Fund Shares	8.18%	10.66%	Dec. 15, 2011
Russell 3000® Value Index (reflects no deduction for expenses, fees, or taxes)		Russell 3000® Value Index	17.55%	21.33%	Dec. 15, 2011

The Russell 3000^® Value Index measures the performance of those Russell 3000^® companies with lower price-to-book ratios and lower forecasted growth values. The stocks in the Russell 3000^® Value Index are also members of either the Russell 1000^® Value Index or the Russell 2000^® Value Index. This index is used to calculate the performance fee adjustment.

After-tax returns are calculated using the historically highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes. Actual after-tax returns depend on your individual tax situation and may differ from those shown in the preceding table. The after-tax return information shown above does not apply to Fund shares held through a tax-deferred account, such as a 401(k) plan or an IRA.

[1] Janus Capital has contractually agreed to waive its investment advisory fee and/or reimburse Fund expenses to the extent that the Fund’s total annual fund operating expenses (excluding any performance adjustments to management fees, administrative services fees payable pursuant to the Transfer Agency Agreement, brokerage commissions, interest, dividends, taxes, acquired fund fees and expenses, and extraordinary expenses) exceed 0.77% until at least November 1, 2014. The contractual waiver may be terminated or modified prior to this date only at the discretion of the Board of Trustees.

XML

Label	Element	Value
Risk/Return:	rr_RiskReturnAbstract
Registrant Name	dei_EntityRegistrantName	JANUS INVESTMENT FUND
Prospectus Date	rr_ProspectusDate	Oct. 28, 2013
Janus Flexible Bond Fund | Class A, C, S, I, N, R, T Shares
Risk/Return:	rr_RiskReturnAbstract
Risk/Return [Heading]	rr_RiskReturnHeading	FUND SUMMARY Janus Flexible Bond Fund
Objective [Heading]	rr_ObjectiveHeading	INVESTMENT OBJECTIVE
Objective, Primary [Text Block]	rr_ObjectivePrimaryTextBlock	Janus Flexible Bond Fund seeks to obtain maximum total return, consistent with preservation of capital.
Expense [Heading]	rr_ExpenseHeading	FEES AND EXPENSES OF THE FUND
Expense Narrative [Text Block]	rr_ExpenseNarrativeTextBlock	This table describes the fees and expenses that you may pay if you buy and hold Shares of the Fund. Each share class has different expenses, but represents an investment in the same Fund.
Shareholder Fees Caption [Text]	rr_ShareholderFeesCaption	SHAREHOLDER FEES (fees paid directly from your investment)
Operating Expenses Caption [Text]	rr_OperatingExpensesCaption	ANNUAL FUND OPERATING EXPENSES (expenses that you pay each year as a percentage of the value of your investment)
Portfolio Turnover [Heading]	rr_PortfolioTurnoverHeading	Portfolio Turnover:
Portfolio Turnover [Text Block]	rr_PortfolioTurnoverTextBlock	The Fund pays transaction costs, such as commissions, when it buys and sells securities (or “turns over” its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when Fund shares are held in a taxable account. These costs, which are not reflected in annual fund operating expenses or in the Example, affect the Fund’s performance. During the most recent fiscal year, the Fund’s portfolio turnover rate was 118% of the average value of its portfolio.
Portfolio Turnover, Rate	rr_PortfolioTurnoverRate	118.00%
Expense Breakpoint Discounts [Text]	rr_ExpenseBreakpointDiscounts	For Class A Shares, you may qualify for sales charge discounts if you and your family invest, or agree to invest in the future, at least $50,000 in the Fund or in other Janus mutual funds. More information about these and other discounts, as well as eligibility requirements for each share class, is available from your financial professional and in the “Purchases” section on page 64 of the Fund’s Prospectus and in the “Purchases” section on page 70 of the Fund’s Statement of Additional Information.
Expense Breakpoint, Minimum Investment Required [Amount]	rr_ExpenseBreakpointMinimumInvestmentRequiredAmount	$ 50,000
Expense Example [Heading]	rr_ExpenseExampleHeading	EXAMPLE:
Expense Example by Year [Heading]	rr_ExpenseExampleByYearHeading	The Example assumes that you invest $10,000 in the Fund for the time periods indicated and reinvest all dividends and distributions. The Example also assumes that your investment has a 5% return each year and that the Fund’s operating expenses remain the same. Although your actual costs may be higher or lower, based on these assumptions your costs would be:
Expense Example Narrative [Text Block]	rr_ExpenseExampleNarrativeTextBlock	The Example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds.
Expense Example by, Year, Caption [Text]	rr_ExpenseExampleByYearCaption	If Shares are redeemed:
Expense Example, No Redemption, By Year, Caption [Text]	rr_ExpenseExampleNoRedemptionByYearCaption	If Shares are not redeemed:
Strategy [Heading]	rr_StrategyHeading	PRINCIPAL INVESTMENT STRATEGIES
Strategy Narrative [Text Block]	rr_StrategyNarrativeTextBlock	The Fund pursues its investment objective by primarily investing, under normal circumstances, at least 80% of its net assets in bonds. Bonds include, but are not limited to, government notes and bonds, corporate bonds, convertible bonds, commercial and residential mortgage-backed securities, and zero-coupon bonds. The Fund will invest at least 65% of its assets in investment grade debt securities. As of June 30, 2013, the Fund’s weighted average maturity was 6.9 years. The Fund will limit its investment in high-yield/high-risk bonds, also known as “junk” bonds, to 35% or less of its net assets. The Fund generates total return from a combination of current income and capital appreciation, but income is usually the dominant portion. The Fund may also invest in asset-backed securities, money market instruments, bank loans, and foreign debt securities (which may include investments in emerging markets). Due to the nature of the securities in which the Fund invests, it may have relatively high portfolio turnover compared to other Funds. In addition, the Fund may invest its assets in derivatives, which are instruments that have a value derived from, or directly linked to, an underlying asset, such as equity securities, fixed-income securities, commodities, currencies, interest rates, or market indices. In particular, the Fund may use interest rate futures to manage portfolio risk. The Fund’s exposure to derivatives will vary. For purposes of meeting its 80% investment policy, the Fund may include derivatives that have characteristics similar to the securities in which the Fund may directly invest. In addition to considering economic factors such as the effect of interest rates on the Fund’s investments, the portfolio managers apply a “bottom up” approach in choosing investments. This means that the portfolio managers look at income-producing securities one at a time to determine if a security is an attractive investment opportunity and if it is consistent with the Fund’s investment policies. The Fund may lend portfolio securities on a short-term or long-term basis, in an amount equal to up to 1/3 of its total assets as determined at the time of the loan origination.
Risk [Heading]	rr_RiskHeading	PRINCIPAL INVESTMENT RISKS
Risk Narrative [Text Block]	rr_RiskNarrativeTextBlock	Although the Fund may be less volatile than funds that invest most of their assets in common stocks, the Fund’s returns and yields will vary, and you could lose money. Fixed-Income Securities Risk. The Fund invests in a variety of fixed-income securities. Typically, the values of fixed-income securities change inversely with prevailing interest rates. Therefore, a fundamental risk of fixed-income securities is interest rate risk, which is the risk that the value of such securities will generally decline as prevailing interest rates rise, which may cause the Fund’s net asset value to likewise decrease. How specific fixed-income securities may react to changes in interest rates will depend on the specific characteristics of each security. Fixed-income securities are also subject to credit risk, prepayment risk, valuation risk, and liquidity risk. Credit risk is the risk that the credit strength of an issuer of a fixed-income security will weaken and/or that the issuer will be unable to make timely principal and interest payments and that the security may go into default. Prepayment risk is the risk that during periods of falling interest rates, certain fixed-income securities with higher interest rates, such as mortgage- and asset-backed securities, may be prepaid by their issuers thereby reducing the amount of interest payments. Valuation risk is the risk that one or more of the fixed-income securities in which the Fund invests are priced differently than the value realized upon such security’s sale. In times of market instability, valuation may be more difficult. Liquidity risk is the risk that fixed-income securities may be difficult or impossible to sell at the time that the portfolio managers would like or at the price the portfolio managers believe the security is currently worth. Mortgage-Backed Securities Risk. Mortgage-backed securities are classified generally as either commercial mortgage-backed securities or residential mortgage-backed securities, each of which is subject to certain specific risks. Mortgage-backed securities tend to be more sensitive to changes in interest rates than other types of debt securities. Investments in mortgage-backed securities are subject to both extension risk, where borrowers extend the duration of their mortgages in times of rising interest rates, and prepayment risk, where borrowers pay off their mortgages sooner than expected in times of declining interest rates. These risks may reduce the Fund’s returns. In addition, investments in mortgage-backed securities, including those comprised of subprime mortgages, may be subject to a higher degree of credit risk, valuation risk, and liquidity risk than various other types of fixed-income securities. Sovereign Debt Risk. The Fund may invest in U.S. and foreign government debt securities (“sovereign debt”). Investments in U.S. sovereign debt are considered low risk. However, investments in non-U.S. sovereign debt can involve a high degree of risk, including the risk that the governmental entity that controls the repayment of sovereign debt may not be willing or able to repay the principal and/or to pay the interest on its sovereign debt in a timely manner. A sovereign debtor’s willingness or ability to satisfy its debt obligation may be affected by various factors including, but not limited to, its cash flow situation, the extent of its foreign currency reserves, the availability of foreign exchange when a payment is due, and the relative size of its debt position in relation to its economy as a whole. In the event of default, there may be limited or no legal remedies for collecting sovereign debt and there may be no bankruptcy proceedings through which the Fund may collect all or part of the sovereign debt that a governmental entity has not repaid. High-Yield/High-Risk Bond Risk. High-yield/high-risk bonds may be more sensitive than other types of bonds to economic changes, political changes, or adverse developments specific to the company that issued the bond, which may adversely affect their value. Bank Loan Risk. Bank loans are obligations of companies or other entities entered into in connection with recapitalizations, acquisitions, and refinancings. The Fund’s investments in bank loans are generally acquired as a participation interest in, or assignment of, loans originated by a lender or other financial institution. These investments may include institutionally-traded floating and fixed-rate debt securities. Participation interests and assignments involve credit, interest rate, and liquidity risk. In addition, the bank loans underlying these securities often involve borrowers with low credit ratings whose financial conditions are troubled or uncertain, including companies that are highly leveraged or in bankruptcy proceedings. Foreign Exposure Risk. The Fund may have exposure to foreign markets as a result of its investments in foreign securities, including investments in emerging markets, which can be more volatile than the U.S. markets. As a result, its returns and net asset value may be affected to a large degree by fluctuations in currency exchange rates or political or economic conditions in a particular country. In some foreign markets, there may not be protection against failure by other parties to complete transactions. It may not be possible for the Fund to repatriate capital, dividends, interest, and other income from a particular country or governmental entity. In addition, a market swing in one or more countries or regions where the Fund has invested a significant amount of its assets may have a greater effect on the Fund’s performance than it would in a more geographically diversified portfolio. To the extent the Fund invests in foreign debt securities, such investments are sensitive to changes in interest rates. Additionally, investments in securities of foreign governments involve the risk that a foreign government may not be willing or able to pay interest or repay principal when due. The Fund’s investments in emerging market countries may involve risks greater than, or in addition to, the risks of investing in more developed countries. Portfolio Turnover Risk. Increased portfolio turnover may result in higher costs, which may have a negative effect on the Fund’s performance. In addition, higher portfolio turnover may result in the acceleration of capital gains and the recognition of greater levels of short-term capital gains, which are taxed at ordinary federal income tax rates when distributed to shareholders. Derivatives Risk. Derivatives can be highly volatile and involve risks in addition to the risks of the underlying referenced securities. Gains or losses from a derivative investment can be substantially greater than the derivative’s original cost, and can therefore involve leverage. Leverage may cause the Fund to be more volatile than if it had not used leverage. Derivatives can be less liquid than other types of investments and entail the risk that the counterparty will default on its payment obligations. Securities Lending Risk. The Fund may seek to earn additional income through lending its securities to certain qualified broker-dealers and institutions. There is the risk that when portfolio securities are lent, the securities may not be returned on a timely basis, and the Fund may experience delays and costs in recovering the security or gaining access to the collateral provided to the Fund to collateralize the loan. If the Fund is unable to recover a security on loan, the Fund may use the collateral to purchase replacement securities in the market. There is a risk that the value of the collateral could decrease below the cost of the replacement security by the time the replacement investment is made, resulting in a loss to the Fund. An investment in the Fund is not a bank deposit and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency.
Risk Lose Money [Text]	rr_RiskLoseMoney	Although the Fund may be less volatile than funds that invest most of their assets in common stocks, the Fund’s returns and yields will vary, and you could lose money.
Risk Not Insured Depository Institution [Text]	rr_RiskNotInsuredDepositoryInstitution	An investment in the Fund is not a bank deposit and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency.
Bar Chart and Performance Table [Heading]	rr_BarChartAndPerformanceTableHeading	PERFORMANCE INFORMATION
Performance Narrative [Text Block]	rr_PerformanceNarrativeTextBlock	The following information provides some indication of the risks of investing in the Fund by showing how the Fund’s performance has varied over time. Class T Shares (formerly named Class J Shares, the initial share class) of the Fund commenced operations with the Fund’s inception. Class A Shares, Class C Shares, Class S Shares, Class I Shares, and Class R Shares of the Fund commenced operations on July 6, 2009. Class N Shares of the Fund commenced operations on May 31, 2012. The performance shown for Class T Shares is calculated using the fees and expenses of Class T Shares in effect during the periods shown, net of any applicable fee and expense limitations or waivers. The performance shown for Class A Shares, Class C Shares, Class S Shares, and Class R Shares for periods prior to July 6, 2009, reflects the performance of the Fund’s former Class J Shares, calculated using the fees and expenses of each respective share class, without the effect of any fee and expense limitations or waivers. The performance shown for Class I Shares for periods prior to July 6, 2009, reflects the performance of the Fund’s former Class J Shares, calculated using the fees and expenses of Class J Shares, net of any applicable fee and expense limitations or waivers. The performance shown for Class N Shares for periods prior to May 31, 2012, reflects the performance of the Fund’s Class T Shares, calculated using the fees and expenses of Class T Shares, net of any applicable fee and expense limitations or waivers. If Class A Shares, Class C Shares, Class S Shares, Class I Shares, and Class R Shares of the Fund had been available during periods prior to July 6, 2009, or Class N Shares of the Fund had been available during periods prior to May 31, 2012, the performance shown for each respective share class may have been different. The performance shown for periods following the Fund’s commencement of Class A Shares, Class C Shares, Class S Shares, Class I Shares, Class N Shares, and Class R Shares reflects the fees and expenses of each respective share class, net of any applicable fee and expense limitations or waivers. The bar chart depicts the change in performance from year to year during the periods indicated. The bar chart figures do not include any applicable sales charges that an investor may pay when they buy or sell Class A Shares or Class C Shares of the Fund. If sales charges were included, the returns would be lower. The table compares the Fund’s average annual returns for the periods indicated to a broad-based securities market index. The index is not actively managed and is not available for direct investment. All figures assume reinvestment of dividends and distributions. For certain periods, the Fund’s performance reflects the effect of expense waivers. Without the effect of these expense waivers, the performance shown would have been lower. The Fund’s past performance (before and after taxes) does not necessarily indicate how it will perform in the future. Updated performance information is available at janus.com/advisor/mutual-funds or by calling 1-877-335-2687.
Performance Information Illustrates Variability of Returns [Text]	rr_PerformanceInformationIllustratesVariabilityOfReturns	The following information provides some indication of the risks of investing in the Fund by showing how the Fund’s performance has varied over time. The bar chart depicts the change in performance from year to year during the periods indicated.
Performance Additional Market Index [Text]	rr_PerformanceAdditionalMarketIndex	The table compares the Fund’s average annual returns for the periods indicated to a broad-based securities market index. The index is not actively managed and is not available for direct investment. All figures assume reinvestment of dividends and distributions.
Performance Availability Phone [Text]	rr_PerformanceAvailabilityPhone	1-877-335-2687
Performance Availability Website Address [Text]	rr_PerformanceAvailabilityWebSiteAddress	janus.com/advisor/mutual-funds
Performance Past Does Not Indicate Future [Text]	rr_PerformancePastDoesNotIndicateFuture	The Fund’s past performance (before and after taxes) does not necessarily indicate how it will perform in the future.
Bar Chart [Heading]	rr_BarChartHeading	Annual Total Returns for Class T Shares (calendar year-end)
Bar Chart Does Not Reflect Sales Loads [Text]	rr_BarChartDoesNotReflectSalesLoads	The bar chart figures do not include any applicable sales charges that an investor may pay when they buy or sell Class A Shares or Class C Shares of the Fund. If sales charges were included, the returns would be lower.
Bar Chart Closing [Text Block]	rr_BarChartClosingTextBlock	Best Quarter:  Third Quarter 2009  5.58%          Worst Quarter:  Second Quarter 2004  −2.99%
Year to Date Return, Label	rr_YearToDateReturnLabel	The Fund’s year-to-date return as of the calendar quarter ended September 30, 2013 was −0.95%.
Performance Table Heading	rr_PerformanceTableHeading	Average Annual Total Returns (periods ended 12/31/12)
Performance Table Uses Highest Federal Rate	rr_PerformanceTableUsesHighestFederalRate	After-tax returns are calculated using the historically highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes.
Performance Table Not Relevant to Tax Deferred	rr_PerformanceTableNotRelevantToTaxDeferred	Actual after-tax returns depend on your individual tax situation and may differ from those shown in the preceding table. The after-tax return information shown above does not apply to Fund shares held through a tax-deferred account, such as a 401(k) plan or an IRA.
Performance Table One Class of after Tax Shown [Text]	rr_PerformanceTableOneClassOfAfterTaxShown	After-tax returns are only shown for Class T Shares of the Fund. After-tax returns for the other classes of Shares will vary from those shown for Class T Shares due to varying sales charges (as applicable), fees, and expenses among the classes.
Performance Table Narrative	rr_PerformanceTableNarrativeTextBlock	After-tax returns are calculated using distributions for the Fund's Class T Shares (formerly named Class J Shares, the initial share class). After-tax returns are calculated using the historically highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes. Actual after-tax returns depend on your individual tax situation and may differ from those shown in the preceding table. The after-tax return information shown above does not apply to Fund shares held through a tax-deferred account, such as a 401(k) plan or an IRA. After-tax returns are only shown for Class T Shares of the Fund. After-tax returns for the other classes of Shares will vary from those shown for Class T Shares due to varying sales charges (as applicable), fees, and expenses among the classes.
Performance Table Closing [Text Block]	rr_PerformanceTableClosingTextBlock	Updated performance information is available at janus.com/advisor/mutual-funds or by calling 1-877-335-2687.
Janus Flexible Bond Fund | Class A, C, S, I, N, R, T Shares | Class A
Risk/Return:	rr_RiskReturnAbstract
Shareholder Fees Column [Text]	rr_ShareholderFeesColumnName	Class A
Maximum Sales Charge (load) Imposed on Purchases (as a percentage of offering price)	rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice	4.75%
Maximum Deferred Sales Charge (load) (as a percentage of the lower of original purchase price or redemption proceeds)	rr_MaximumDeferredSalesChargeOverOther	none
Operating Expenses Column [Text]	rr_OperatingExpensesColumnName	Class A
Management Fees	rr_ManagementFeesOverAssets	0.40%
Distribution/Service (12b-1) Fees	rr_DistributionAndService12b1FeesOverAssets	0.25%
Other Expenses	rr_OtherExpensesOverAssets	0.10%
Total Annual Fund Operating Expenses	rr_ExpensesOverAssets	0.75%
Expense Example, By Year, Column [Text]	rr_ExpenseExampleByYearColumnName	Class A Shares
1 Year	rr_ExpenseExampleYear01	548
3 Years	rr_ExpenseExampleYear03	703
5 Years	rr_ExpenseExampleYear05	872
10 Years	rr_ExpenseExampleYear10	1,361
Expense Example, No Redemption, By Year, Column [Text]	rr_ExpenseExampleNoRedemptionByYearColumnName	Class A Shares
1 Year	rr_ExpenseExampleNoRedemptionYear01	548
3 Years	rr_ExpenseExampleNoRedemptionYear03	703
5 Years	rr_ExpenseExampleNoRedemptionYear05	872
10 Years	rr_ExpenseExampleNoRedemptionYear10	1,361
Janus Flexible Bond Fund | Class A, C, S, I, N, R, T Shares | Class C
Risk/Return:	rr_RiskReturnAbstract
Shareholder Fees Column [Text]	rr_ShareholderFeesColumnName	Class C
Maximum Sales Charge (load) Imposed on Purchases (as a percentage of offering price)	rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice	none
Maximum Deferred Sales Charge (load) (as a percentage of the lower of original purchase price or redemption proceeds)	rr_MaximumDeferredSalesChargeOverOther	1.00%
Operating Expenses Column [Text]	rr_OperatingExpensesColumnName	Class C
Management Fees	rr_ManagementFeesOverAssets	0.40%
Distribution/Service (12b-1) Fees	rr_DistributionAndService12b1FeesOverAssets	1.00%
Other Expenses	rr_OtherExpensesOverAssets	0.15%
Total Annual Fund Operating Expenses	rr_ExpensesOverAssets	1.55%
Expense Example, By Year, Column [Text]	rr_ExpenseExampleByYearColumnName	Class C Shares
1 Year	rr_ExpenseExampleYear01	258
3 Years	rr_ExpenseExampleYear03	490
5 Years	rr_ExpenseExampleYear05	845
10 Years	rr_ExpenseExampleYear10	1,845
Expense Example, No Redemption, By Year, Column [Text]	rr_ExpenseExampleNoRedemptionByYearColumnName	Class C Shares
1 Year	rr_ExpenseExampleNoRedemptionYear01	158
3 Years	rr_ExpenseExampleNoRedemptionYear03	490
5 Years	rr_ExpenseExampleNoRedemptionYear05	845
10 Years	rr_ExpenseExampleNoRedemptionYear10	1,845
Janus Flexible Bond Fund | Class A, C, S, I, N, R, T Shares | Class S
Risk/Return:	rr_RiskReturnAbstract
Shareholder Fees Column [Text]	rr_ShareholderFeesColumnName	Class S
Maximum Sales Charge (load) Imposed on Purchases (as a percentage of offering price)	rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice	none
Maximum Deferred Sales Charge (load) (as a percentage of the lower of original purchase price or redemption proceeds)	rr_MaximumDeferredSalesChargeOverOther	none
Operating Expenses Column [Text]	rr_OperatingExpensesColumnName	Class S
Management Fees	rr_ManagementFeesOverAssets	0.40%
Distribution/Service (12b-1) Fees	rr_DistributionAndService12b1FeesOverAssets	0.25%
Other Expenses	rr_OtherExpensesOverAssets	0.30%
Total Annual Fund Operating Expenses	rr_ExpensesOverAssets	0.95%
Expense Example, By Year, Column [Text]	rr_ExpenseExampleByYearColumnName	Class S Shares
1 Year	rr_ExpenseExampleYear01	97
3 Years	rr_ExpenseExampleYear03	303
5 Years	rr_ExpenseExampleYear05	525
10 Years	rr_ExpenseExampleYear10	1,166
Expense Example, No Redemption, By Year, Column [Text]	rr_ExpenseExampleNoRedemptionByYearColumnName	Class S Shares
1 Year	rr_ExpenseExampleNoRedemptionYear01	97
3 Years	rr_ExpenseExampleNoRedemptionYear03	303
5 Years	rr_ExpenseExampleNoRedemptionYear05	525
10 Years	rr_ExpenseExampleNoRedemptionYear10	1,166
Janus Flexible Bond Fund | Class A, C, S, I, N, R, T Shares | Class I
Risk/Return:	rr_RiskReturnAbstract
Shareholder Fees Column [Text]	rr_ShareholderFeesColumnName	Class I
Maximum Sales Charge (load) Imposed on Purchases (as a percentage of offering price)	rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice	none
Maximum Deferred Sales Charge (load) (as a percentage of the lower of original purchase price or redemption proceeds)	rr_MaximumDeferredSalesChargeOverOther	none
Operating Expenses Column [Text]	rr_OperatingExpensesColumnName	Class I
Management Fees	rr_ManagementFeesOverAssets	0.40%
Distribution/Service (12b-1) Fees	rr_DistributionAndService12b1FeesOverAssets	none
Other Expenses	rr_OtherExpensesOverAssets	0.16%
Total Annual Fund Operating Expenses	rr_ExpensesOverAssets	0.56%
Expense Example, By Year, Column [Text]	rr_ExpenseExampleByYearColumnName	Class I Shares
1 Year	rr_ExpenseExampleYear01	57
3 Years	rr_ExpenseExampleYear03	179
5 Years	rr_ExpenseExampleYear05	313
10 Years	rr_ExpenseExampleYear10	701
Expense Example, No Redemption, By Year, Column [Text]	rr_ExpenseExampleNoRedemptionByYearColumnName	Class I Shares
1 Year	rr_ExpenseExampleNoRedemptionYear01	57
3 Years	rr_ExpenseExampleNoRedemptionYear03	179
5 Years	rr_ExpenseExampleNoRedemptionYear05	313
10 Years	rr_ExpenseExampleNoRedemptionYear10	701
Janus Flexible Bond Fund | Class A, C, S, I, N, R, T Shares | Class N
Risk/Return:	rr_RiskReturnAbstract
Shareholder Fees Column [Text]	rr_ShareholderFeesColumnName	Class N
Maximum Sales Charge (load) Imposed on Purchases (as a percentage of offering price)	rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice	none
Maximum Deferred Sales Charge (load) (as a percentage of the lower of original purchase price or redemption proceeds)	rr_MaximumDeferredSalesChargeOverOther	none
Operating Expenses Column [Text]	rr_OperatingExpensesColumnName	Class N
Management Fees	rr_ManagementFeesOverAssets	0.40%
Distribution/Service (12b-1) Fees	rr_DistributionAndService12b1FeesOverAssets	none
Other Expenses	rr_OtherExpensesOverAssets	0.04%
Total Annual Fund Operating Expenses	rr_ExpensesOverAssets	0.44%
Expense Example, By Year, Column [Text]	rr_ExpenseExampleByYearColumnName	Class N Shares
1 Year	rr_ExpenseExampleYear01	45
3 Years	rr_ExpenseExampleYear03	141
5 Years	rr_ExpenseExampleYear05	246
10 Years	rr_ExpenseExampleYear10	555
Expense Example, No Redemption, By Year, Column [Text]	rr_ExpenseExampleNoRedemptionByYearColumnName	Class N Shares
1 Year	rr_ExpenseExampleNoRedemptionYear01	45
3 Years	rr_ExpenseExampleNoRedemptionYear03	141
5 Years	rr_ExpenseExampleNoRedemptionYear05	246
10 Years	rr_ExpenseExampleNoRedemptionYear10	555
Janus Flexible Bond Fund | Class A, C, S, I, N, R, T Shares | Class R
Risk/Return:	rr_RiskReturnAbstract
Shareholder Fees Column [Text]	rr_ShareholderFeesColumnName	Class R
Maximum Sales Charge (load) Imposed on Purchases (as a percentage of offering price)	rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice	none
Maximum Deferred Sales Charge (load) (as a percentage of the lower of original purchase price or redemption proceeds)	rr_MaximumDeferredSalesChargeOverOther	none
Operating Expenses Column [Text]	rr_OperatingExpensesColumnName	Class R
Management Fees	rr_ManagementFeesOverAssets	0.40%
Distribution/Service (12b-1) Fees	rr_DistributionAndService12b1FeesOverAssets	0.50%
Other Expenses	rr_OtherExpensesOverAssets	0.29%
Total Annual Fund Operating Expenses	rr_ExpensesOverAssets	1.19%
Expense Example, By Year, Column [Text]	rr_ExpenseExampleByYearColumnName	Class R Shares
1 Year	rr_ExpenseExampleYear01	121
3 Years	rr_ExpenseExampleYear03	378
5 Years	rr_ExpenseExampleYear05	654
10 Years	rr_ExpenseExampleYear10	1,443
Expense Example, No Redemption, By Year, Column [Text]	rr_ExpenseExampleNoRedemptionByYearColumnName	Class R Shares
1 Year	rr_ExpenseExampleNoRedemptionYear01	121
3 Years	rr_ExpenseExampleNoRedemptionYear03	378
5 Years	rr_ExpenseExampleNoRedemptionYear05	654
10 Years	rr_ExpenseExampleNoRedemptionYear10	1,443
Janus Flexible Bond Fund | Class A, C, S, I, N, R, T Shares | Class T
Risk/Return:	rr_RiskReturnAbstract
Shareholder Fees Column [Text]	rr_ShareholderFeesColumnName	Class T
Maximum Sales Charge (load) Imposed on Purchases (as a percentage of offering price)	rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice	none
Maximum Deferred Sales Charge (load) (as a percentage of the lower of original purchase price or redemption proceeds)	rr_MaximumDeferredSalesChargeOverOther	none
Operating Expenses Column [Text]	rr_OperatingExpensesColumnName	Class T
Management Fees	rr_ManagementFeesOverAssets	0.40%
Distribution/Service (12b-1) Fees	rr_DistributionAndService12b1FeesOverAssets	none
Other Expenses	rr_OtherExpensesOverAssets	0.30%
Total Annual Fund Operating Expenses	rr_ExpensesOverAssets	0.70%
Expense Example, By Year, Column [Text]	rr_ExpenseExampleByYearColumnName	Class T Shares
1 Year	rr_ExpenseExampleYear01	72
3 Years	rr_ExpenseExampleYear03	224
5 Years	rr_ExpenseExampleYear05	390
10 Years	rr_ExpenseExampleYear10	871
Expense Example, No Redemption, By Year, Column [Text]	rr_ExpenseExampleNoRedemptionByYearColumnName	Class T Shares
1 Year	rr_ExpenseExampleNoRedemptionYear01	72
3 Years	rr_ExpenseExampleNoRedemptionYear03	224
5 Years	rr_ExpenseExampleNoRedemptionYear05	390
10 Years	rr_ExpenseExampleNoRedemptionYear10	$ 871
2003	rr_AnnualReturn2003	6.37%
2004	rr_AnnualReturn2004	3.82%
2005	rr_AnnualReturn2005	1.79%
2006	rr_AnnualReturn2006	4.12%
2007	rr_AnnualReturn2007	6.87%
2008	rr_AnnualReturn2008	5.64%
2009	rr_AnnualReturn2009	12.54%
2010	rr_AnnualReturn2010	7.45%
2011	rr_AnnualReturn2011	6.50%
2012	rr_AnnualReturn2012	7.91%
Bar Chart, Year to Date Return, Date	rr_BarChartYearToDateReturnDate	Sep. 30, 2013
Bar Chart, Year to Date Return	rr_BarChartYearToDateReturn	(0.95%)
Highest Quarterly Return, Label	rr_HighestQuarterlyReturnLabel	Best Quarter:
Highest Quarterly Return, Date	rr_BarChartHighestQuarterlyReturnDate	Sep. 30, 2009
Highest Quarterly Return	rr_BarChartHighestQuarterlyReturn	5.58%
Lowest Quarterly Return, Label	rr_LowestQuarterlyReturnLabel	Worst Quarter
Lowest Quarterly Return, Date	rr_BarChartLowestQuarterlyReturnDate	Jun. 30, 2004
Lowest Quarterly Return	rr_BarChartLowestQuarterlyReturn	(2.99%)
Janus Flexible Bond Fund | Class A, C, S, I, N, R, T Shares | Return Before Taxes | Class A
Risk/Return:	rr_RiskReturnAbstract
Column	rr_AverageAnnualReturnColumnName	Class A Shares
Label	rr_AverageAnnualReturnLabel	Return Before Taxes	[1]
1 Year	rr_AverageAnnualReturnYear01	2.66%
5 Years	rr_AverageAnnualReturnYear05	6.87%
10 Years	rr_AverageAnnualReturnYear10	5.71%
Since Inception	rr_AverageAnnualReturnSinceInception	7.33%
Inception Date	rr_AverageAnnualReturnInceptionDate	Jul. 07, 1987
Janus Flexible Bond Fund | Class A, C, S, I, N, R, T Shares | Return Before Taxes | Class C
Risk/Return:	rr_RiskReturnAbstract
Column	rr_AverageAnnualReturnColumnName	Class C Shares
Label	rr_AverageAnnualReturnLabel	Return Before Taxes	[2]
1 Year	rr_AverageAnnualReturnYear01	5.97%
5 Years	rr_AverageAnnualReturnYear05	7.14%
10 Years	rr_AverageAnnualReturnYear10	5.48%
Since Inception	rr_AverageAnnualReturnSinceInception	6.85%
Inception Date	rr_AverageAnnualReturnInceptionDate	Jul. 07, 1987
Janus Flexible Bond Fund | Class A, C, S, I, N, R, T Shares | Return Before Taxes | Class S
Risk/Return:	rr_RiskReturnAbstract
Column	rr_AverageAnnualReturnColumnName	Class S Shares
Label	rr_AverageAnnualReturnLabel	Return Before Taxes
1 Year	rr_AverageAnnualReturnYear01	7.54%
5 Years	rr_AverageAnnualReturnYear05	7.71%
10 Years	rr_AverageAnnualReturnYear10	6.03%
Since Inception	rr_AverageAnnualReturnSinceInception	7.39%
Inception Date	rr_AverageAnnualReturnInceptionDate	Jul. 07, 1987
Janus Flexible Bond Fund | Class A, C, S, I, N, R, T Shares | Return Before Taxes | Class I
Risk/Return:	rr_RiskReturnAbstract
Column	rr_AverageAnnualReturnColumnName	Class I Shares
Label	rr_AverageAnnualReturnLabel	Return Before Taxes
1 Year	rr_AverageAnnualReturnYear01	8.06%
5 Years	rr_AverageAnnualReturnYear05	7.98%
10 Years	rr_AverageAnnualReturnYear10	6.27%
Since Inception	rr_AverageAnnualReturnSinceInception	7.55%
Inception Date	rr_AverageAnnualReturnInceptionDate	Jul. 07, 1987
Janus Flexible Bond Fund | Class A, C, S, I, N, R, T Shares | Return Before Taxes | Class N
Risk/Return:	rr_RiskReturnAbstract
Column	rr_AverageAnnualReturnColumnName	Class N Shares
Label	rr_AverageAnnualReturnLabel	Return Before Taxes
1 Year	rr_AverageAnnualReturnYear01	7.91%
5 Years	rr_AverageAnnualReturnYear05	7.98%
10 Years	rr_AverageAnnualReturnYear10	6.27%
Since Inception	rr_AverageAnnualReturnSinceInception	7.55%
Inception Date	rr_AverageAnnualReturnInceptionDate	Jul. 07, 1987
Janus Flexible Bond Fund | Class A, C, S, I, N, R, T Shares | Return Before Taxes | Class R
Risk/Return:	rr_RiskReturnAbstract
Column	rr_AverageAnnualReturnColumnName	Class R Shares
Label	rr_AverageAnnualReturnLabel	Return Before Taxes
1 Year	rr_AverageAnnualReturnYear01	7.40%
5 Years	rr_AverageAnnualReturnYear05	7.46%
10 Years	rr_AverageAnnualReturnYear10	5.77%
Since Inception	rr_AverageAnnualReturnSinceInception	7.13%
Inception Date	rr_AverageAnnualReturnInceptionDate	Jul. 07, 1987
Janus Flexible Bond Fund | Class A, C, S, I, N, R, T Shares | Return Before Taxes | Class T
Risk/Return:	rr_RiskReturnAbstract
Column	rr_AverageAnnualReturnColumnName	Class T Shares
Label	rr_AverageAnnualReturnLabel	Return Before Taxes
1 Year	rr_AverageAnnualReturnYear01	7.91%
5 Years	rr_AverageAnnualReturnYear05	7.98%
10 Years	rr_AverageAnnualReturnYear10	6.27%
Since Inception	rr_AverageAnnualReturnSinceInception	7.55%
Inception Date	rr_AverageAnnualReturnInceptionDate	Jul. 07, 1987
Janus Flexible Bond Fund | Class A, C, S, I, N, R, T Shares | Return After Taxes on Distributions | Class T
Risk/Return:	rr_RiskReturnAbstract
Column	rr_AverageAnnualReturnColumnName	Class T Shares
Label	rr_AverageAnnualReturnLabel	Return After Taxes on Distributions
1 Year	rr_AverageAnnualReturnYear01	6.24%
5 Years	rr_AverageAnnualReturnYear05	6.14%
10 Years	rr_AverageAnnualReturnYear10	4.52%
Since Inception	rr_AverageAnnualReturnSinceInception	4.97%
Inception Date	rr_AverageAnnualReturnInceptionDate	Jul. 07, 1987
Janus Flexible Bond Fund | Class A, C, S, I, N, R, T Shares | Return After Taxes on Distributions and Sale of Fund Shares | Class T
Risk/Return:	rr_RiskReturnAbstract
Column	rr_AverageAnnualReturnColumnName	Class T Shares
Label	rr_AverageAnnualReturnLabel	Return After Taxes on Distributions and Sale of Fund Shares
1 Year	rr_AverageAnnualReturnYear01	5.31%
5 Years	rr_AverageAnnualReturnYear05	5.82%
10 Years	rr_AverageAnnualReturnYear10	4.36%
Since Inception	rr_AverageAnnualReturnSinceInception	4.91%
Inception Date	rr_AverageAnnualReturnInceptionDate	Jul. 07, 1987
Janus Flexible Bond Fund | Class A, C, S, I, N, R, T Shares | Barclays U.S. Aggregate Bond Index (reflects no deduction for expenses, fees, or taxes)
Risk/Return:	rr_RiskReturnAbstract
Label	rr_AverageAnnualReturnLabel	Barclays U.S. Aggregate Bond Index
1 Year	rr_AverageAnnualReturnYear01	4.21%
5 Years	rr_AverageAnnualReturnYear05	5.95%
10 Years	rr_AverageAnnualReturnYear10	5.18%
Since Inception	rr_AverageAnnualReturnSinceInception	7.21%
Inception Date	rr_AverageAnnualReturnInceptionDate	Jul. 07, 1987

[1] Calculated assuming maximum permitted sales loads.

[2] The one year return is calculated to include the contingent deferred sales charge.

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Perkins Small Cap Value Fund | Class D Shares

FUND SUMMARY

Perkins Small Cap Value Fund

INVESTMENT OBJECTIVE

Perkins Small Cap Value Fund seeks capital appreciation.

FEES AND EXPENSES OF THE FUND

This table describes the fees and expenses that you may pay if you buy and hold Shares of the Fund.

ANNUAL FUND OPERATING EXPENSES
(expenses that you pay each year as a percentage of the value of your investment)

Annual Fund Operating Expenses	Perkins Small Cap Value Fund Class D Shares Class D
Operating Expenses Column [Text]	Class D
Management Fees (may adjust up or down)	0.56%
Other Expenses	0.21%
Total Annual Fund Operating Expenses	0.77%

EXAMPLE:

The Example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds.

The Example assumes that you invest $10,000 in the Fund for the time periods indicated, reinvest all dividends and distributions, and then redeem all of your Shares at the end of each period. The Example also assumes that your investment has a 5% return each year and that the Fund’s operating expenses remain the same. Although your actual costs may be higher or lower, based on these assumptions your costs would be:

Expense Example (USD $)	Expense Example, By Year, Column [Text]	1 Year	3 Years	5 Years	10 Years
Perkins Small Cap Value Fund Class D Shares Class D	Class D Shares	79	246	428	954

Portfolio Turnover:

The Fund pays transaction costs, such as commissions, when it buys and sells securities (or “turns over” its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when Fund shares are held in a taxable account. These costs, which are not reflected in annual fund operating expenses or in the Example, affect the Fund’s performance. During the most recent fiscal year, the Fund’s portfolio turnover rate was 60% of the average value of its portfolio.

PRINCIPAL INVESTMENT STRATEGIES

The Fund pursues its investment objective by investing primarily in the common stocks of small companies whose stock prices are believed to be undervalued by the Fund’s portfolio managers. The Fund invests, under normal circumstances, at least 80% of its net assets in equity securities of small companies whose market capitalization, at the time of initial purchase, is less than the 12-month average of the maximum market capitalization for companies included in the Russell 2000^® Value Index. This average is updated monthly. The market capitalizations within the index will vary, but as of June 30, 2013, they ranged from approximately $23 million to $5.6 billion. The Fund may also invest in foreign equity and debt securities, which may include investments in emerging markets. The Fund may invest, under normal circumstances, up to 20% of its net assets in securities of companies having market capitalizations outside of the aforementioned market capitalization ranges. In addition, when the portfolio managers believe that market conditions are unfavorable for investing, or when they are otherwise unable to locate attractive investment opportunities, the Fund may invest up to 20% of its net assets in cash or similar investments.

The Fund’s securities selection focuses on companies that are out of favor with markets or have not yet been discovered by the broader investment community. The Fund’s portfolio managers generally look for companies with:

• strong balance sheets and solid recurring free cash flows
• attractive relative and absolute valuation ratios or that have underperformed recently
• favorable reward to risk characteristics

The portfolio managers’ philosophy is to weigh a security’s downside risk before considering its upside potential, which may help provide an element of capital preservation.

PRINCIPAL INVESTMENT RISKS

The biggest risk is that the Fund’s returns will vary, and you could lose money. The Fund is designed for long-term investors seeking an equity portfolio, including common stocks. Common stocks tend to be more volatile than many other investment choices.

Value Investing Risk. Because different types of stocks tend to shift in and out of favor depending on market and economic conditions, “value” stocks may perform differently than other types of stocks and from the market as a whole, and can continue to be undervalued by the market for long periods of time. It is also possible that a value stock will never appreciate to the extent expected by the portfolio managers. When the Fund’s investments in cash or similar investments increase due to a lack of favorable investment opportunities or other extraordinary factors, the Fund may not participate in market advances or declines to the same extent that it would if the Fund had been fully invested.

Market Risk. The value of the Fund’s portfolio may decrease if the value of an individual company or security, or multiple companies or securities, in the portfolio decreases or if the portfolio managers’ belief about a company’s intrinsic worth is incorrect. Further, regardless of how well individual companies or securities perform, the value of the Fund’s portfolio could also decrease if there are deteriorating economic or market conditions. It is important to understand that the value of your investment may fall, sometimes sharply, in response to changes in the market, and you could lose money.

Small-Sized Companies Risk. The Fund’s investments in securities issued by small-sized companies, which can include smaller, start-up companies offering emerging products or services, may involve greater risks than are customarily associated with larger, more established companies. Securities issued by small-sized companies tend to be more volatile and somewhat more speculative than securities issued by larger or more established companies and may underperform as compared to the securities of larger companies.

Real Estate Securities Risk. The Fund’s performance may be affected by the risks associated with investments in real estate-related companies. The value of real estate-related companies’ securities is sensitive to changes in real estate values and rental income, property taxes, interest rates, tax and regulatory requirements, supply and demand, and the management skill and creditworthiness of the company. Investments in real estate investment trusts (“REITs”) involve the same risks as other real estate investments. In addition, a REIT could fail to qualify for tax-free pass-through of its income under the Internal Revenue Code or fail to maintain its exemption from registration under the Investment Company Act of 1940, as amended, which could produce adverse economic consequences for the REIT and its investors, including the Fund.

An investment in the Fund is not a bank deposit and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency.

PERFORMANCE INFORMATION

The following information provides some indication of the risks of investing in the Fund by showing how the Fund’s performance has varied over time. Class D Shares of the Fund commenced operations on February 16, 2010, as a result of the restructuring of Class J Shares. The performance shown for Class D Shares for periods prior to February 16, 2010, reflects the performance of the Fund’s former Class J Shares (formerly named Investor Shares). For the periods prior to April 21, 2003, the performance shown for Class D Shares reflects the historical performance of Berger Small Cap Value Fund – Investor Shares (as a result of a prior reorganization of Berger Small Cap Value Fund – Investor Shares into the Fund’s former Class J Shares). If Class D Shares of the Fund had been available during periods prior to February 16, 2010, the performance shown may have been different. The performance shown for periods following the Fund’s commencement of Class D Shares reflects the fees and expenses of Class D Shares, net of any applicable fee and expense limitations or waivers.

The bar chart depicts the change in performance from year to year during the periods indicated. The table compares the Fund’s average annual returns for the periods indicated to a broad-based securities market index. The index is not actively managed and is not available for direct investment. All figures assume reinvestment of dividends and distributions. For certain periods, the Fund’s performance reflects the effect of expense waivers. Without the effect of these expense waivers, the performance shown would have been lower.

The Fund’s past performance (before and after taxes) does not necessarily indicate how it will perform in the future. Updated performance information is available at janus.com/allfunds or by calling 1-800-525-3713.

Annual Total Returns for Class D Shares (calendar year-end)

Best Quarter:  Second Quarter 2009  23.04%          Worst Quarter:  Fourth Quarter 2008  −18.83%

The Fund’s year-to-date return as of the calendar quarter ended September 30, 2013 was 18.51%.

Average Annual Total Returns (periods ended 12/31/12)

Average Annual Total Returns Perkins Small Cap Value Fund Class D Shares	Column	Label		1 Year	5 Years	10 Years
Class D Return Before Taxes	Class D Shares	Return Before Taxes		9.07%	5.86%	10.03%
Class D Return After Taxes on Distributions	Class D Shares	Return After Taxes on Distributions		8.19%	4.63%	8.12%
Class D Return After Taxes on Distributions and Sale of Fund Shares	Class D Shares	Return After Taxes on Distributions and Sale of Fund Shares	[1]	7.09%	4.69%	8.25%
Russell 2000® Value Index (reflects no deduction for expenses, fees, or taxes)		Russell 2000® Value Index		18.05%	3.55%	9.50%

The Russell 2000^® Value Index measures the performance of those Russell 2000^® companies with lower price-to-book ratios and lower forecasted growth values. This index is used to calculate the performance fee adjustment.

After-tax returns are calculated using distributions for the Fund’s Class D Shares for the periods following February 16, 2010; for the Fund’s Class J Shares (formerly named Investor Shares) for the period April 21, 2003 to February 16, 2010; and for Berger Small Cap Value Fund – Investor Shares for periods prior to April 21, 2003. If Class D Shares of the Fund had been available during these earlier periods, distributions may have been different and thus, after-tax returns may have been different from those shown. After-tax returns are calculated using the historically highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes. Actual after-tax returns depend on your individual tax situation and may differ from those shown in the preceding table. The after-tax return information shown above does not apply to Fund shares held through a tax-deferred account, such as a 401(k) plan or an IRA.

[1] If the Fund incurs a loss, which generates a tax benefit, the Return After Taxes on Distributions and Sale of Fund Shares may exceed the Fund’s other return figures.

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Label	Element	Value
Risk/Return:	rr_RiskReturnAbstract
Registrant Name	dei_EntityRegistrantName	JANUS INVESTMENT FUND
Prospectus Date	rr_ProspectusDate	Oct. 28, 2013
Janus Real Return Fund | Class A, C, S, I, T Shares
Risk/Return:	rr_RiskReturnAbstract
Risk/Return [Heading]	rr_RiskReturnHeading	FUND SUMMARY Janus Real Return Fund
Objective [Heading]	rr_ObjectiveHeading	INVESTMENT OBJECTIVE
Objective, Primary [Text Block]	rr_ObjectivePrimaryTextBlock	Janus Real Return Fund seeks real return consistent with preservation of capital.
Expense [Heading]	rr_ExpenseHeading	FEES AND EXPENSES OF THE FUND
Expense Narrative [Text Block]	rr_ExpenseNarrativeTextBlock	This table describes the fees and expenses that you may pay if you buy and hold Shares of the Fund. Each share class has different expenses, but represents an investment in the same Fund.
Shareholder Fees Caption [Text]	rr_ShareholderFeesCaption	SHAREHOLDER FEES (fees paid directly from your investment)
Operating Expenses Caption [Text]	rr_OperatingExpensesCaption	ANNUAL FUND OPERATING EXPENSES (expenses that you pay each year as a percentage of the value of your investment)
Fee Waiver or Reimbursement over Assets, Date of Termination	rr_FeeWaiverOrReimbursementOverAssetsDateOfTermination	November 1, 2014
Portfolio Turnover [Heading]	rr_PortfolioTurnoverHeading	Portfolio Turnover:
Portfolio Turnover [Text Block]	rr_PortfolioTurnoverTextBlock	The Fund pays transaction costs, such as commissions, when it buys and sells securities (or “turns over” its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when Fund shares are held in a taxable account. These costs, which are not reflected in annual fund operating expenses or in the Example, affect the Fund’s performance. During the most recent fiscal year, the Fund’s portfolio turnover rate was 112% of the average value of its portfolio.
Portfolio Turnover, Rate	rr_PortfolioTurnoverRate	112.00%
Expense Breakpoint Discounts [Text]	rr_ExpenseBreakpointDiscounts	For Class A Shares, you may qualify for sales charge discounts if you and your family invest, or agree to invest in the future, at least $50,000 in the Fund or in other Janus mutual funds. More information about these and other discounts, as well as eligibility requirements for each share class, is available from your financial professional and in the “Purchases” section on page 64 of the Fund’s Prospectus and in the “Purchases” section on page 70 of the Fund’s Statement of Additional Information.
Expense Breakpoint, Minimum Investment Required [Amount]	rr_ExpenseBreakpointMinimumInvestmentRequiredAmount	$ 50,000
Expense Example [Heading]	rr_ExpenseExampleHeading	EXAMPLE:
Expense Example by Year [Heading]	rr_ExpenseExampleByYearHeading	The Example assumes that you invest $10,000 in the Fund for the time periods indicated and reinvest all dividends and distributions. The Example also assumes that your investment has a 5% return each year and that the Fund’s operating expenses without waivers or recoupments (if applicable) remain the same. Although your actual costs may be higher or lower, based on these assumptions your costs would be:
Expense Example Narrative [Text Block]	rr_ExpenseExampleNarrativeTextBlock	The following Example is based on expenses without waivers. The Example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds.
Expense Example by, Year, Caption [Text]	rr_ExpenseExampleByYearCaption	If Shares are redeemed:
Expense Example, No Redemption, By Year, Caption [Text]	rr_ExpenseExampleNoRedemptionByYearCaption	If Shares are not redeemed:
Strategy [Heading]	rr_StrategyHeading	PRINCIPAL INVESTMENT STRATEGIES
Strategy Narrative [Text Block]	rr_StrategyNarrativeTextBlock	The Fund pursues its investment objective by primarily investing in U.S. Treasury securities, short-duration high-yield/high-risk debt, commodity-linked investments, and equity securities. The Fund’s investments in U.S. Treasury securities may also include Treasury Inflation-Protected Securities, also known as TIPS. As utilized by the Fund, each of these types of investments may be considered an “inflation-related investment,” which are those that may provide what is known as “real return,” or a rate of return above the rate of inflation over a full market cycle. Due to the nature of securities in which the Fund invests, it may have relatively high portfolio turnover compared to other funds. The Fund may invest up to 90% of its net assets in short-duration high-yield/high-risk debt securities. The Fund’s investments in short-duration high-yield/high-risk securities include debt rated below investment grade, also known as “junk” bonds. Securities rated below investment grade may include their unrated equivalents or other high-yielding securities the portfolio managers believe offer attractive risk/return characteristics. The Fund may also invest in certain investment grade debt instruments, including corporate bonds, government bonds, municipal bonds, mortgage-backed securities, zero-coupon bonds, and agency securities. The Fund may invest in foreign debt securities. To seek exposure to the commodities markets, the Fund may invest in commodity-linked investments such as commodity-related exchange-traded funds (“ETFs”), commodity index-linked swap agreements, commodity options and futures, and options on futures that provide exposure to the investment returns of the commodities markets. The Fund may also invest in other commodity-linked derivative instruments, such as commodity-linked notes (“structured notes”). The Fund’s investments in equity securities may include common stock, preferred stock, and convertible securities, all of which may include exposure to foreign markets. The Fund may invest in companies of any market capitalization. The Fund’s equity investments may also include securities of real estate-related companies, including, but not limited to, real estate investment trusts (“REITs”) and similar REIT-like entities, such as foreign entities that have REIT characteristics. The Fund may also invest in derivative instruments (by taking long and/or short positions) for various purposes, including hedging by shorting interest rate futures against long positions in TIPS, using inflation index swaps to hedge against unexpected changes in the rate of inflation, using interest rate swaps to hedge against changes in interest rates, using currency swaps to adjust its currency exposure, to increase or decrease the Fund’s exposure to a particular market, to manage or adjust the risk profile of the Fund related to an investment, and to earn income and enhance returns. The Fund’s exposure to derivatives will vary, is not limited to those derivatives listed, and could be significant at times. The Fund may also use reverse repurchase agreements to generate income as part of its inflation-related strategies. Proceeds from reverse repurchase agreement transactions may be invested in other securities or instruments to attempt to increase the Fund’s investment return. The Fund may also invest in money market instruments, buy backs or dollar rolls, other securitized debt products, bank loans, various when-issued securities, exchange-traded notes, and other investment companies. In addition to considering economic factors such as the rate of inflation and the effect of interest rates on the Fund’s investments, the portfolio managers apply a “bottom up” approach in choosing investments. This means that the portfolio managers look at securities one at a time to determine if a security is an attractive investment opportunity and if it is consistent with the Fund’s investment policies. The Fund may lend portfolio securities on a short-term or long-term basis, in an amount equal to up to 1/3 of its total assets as determined at the time of the loan origination.
Risk [Heading]	rr_RiskHeading	PRINCIPAL INVESTMENT RISKS
Risk Narrative [Text Block]	rr_RiskNarrativeTextBlock	Although the Fund may be less volatile than funds that invest most of their assets in common stocks, the Fund’s returns and yields will vary, and you could lose money. Fixed-Income Securities Risk. The Fund invests in a variety of fixed-income securities. Typically, the values of fixed-income securities change inversely with prevailing interest rates. Therefore, a fundamental risk of fixed-income securities is interest rate risk, which is the risk that the value of such securities will generally decline as prevailing interest rates rise, which may cause the Fund’s net asset value to likewise decrease. How specific fixed-income securities may react to changes in interest rates will depend on the specific characteristics of each security. Fixed-income securities are also subject to credit risk, prepayment risk, valuation risk, and liquidity risk. Credit risk is the risk that the credit strength of an issuer of a fixed-income security will weaken and/or that the issuer will be unable to make timely principal and interest payments and that the security may go into default. Prepayment risk is the risk that during periods of falling interest rates, certain fixed-income securities with higher interest rates, such as mortgage- and asset-backed securities, may be prepaid by their issuers thereby reducing the amount of interest payments. Valuation risk is the risk that one or more of the fixed-income securities in which the Fund invests are priced differently than the value realized upon such security’s sale. In times of market instability, valuation may be more difficult. Liquidity risk is the risk that fixed-income securities may be difficult or impossible to sell at the time that the portfolio managers would like or at the price the portfolio managers believe the security is currently worth. High-Yield/High-Risk Bond Risk. The Fund may invest up to 90% of its net assets in higher-yielding/higher-risk bonds, also known as “junk” bonds. High-yield/high-risk bonds may be more sensitive than other types of bonds to economic changes, political changes, or adverse developments specific to the company that issued the bond, which may adversely affect their value. Sovereign Debt Risk. The Fund may invest in U.S. and foreign government debt securities (“sovereign debt”). Investments in U.S. sovereign debt are considered low risk. However, investments in non-U.S. sovereign debt can involve a high degree of risk, including the risk that the governmental entity that controls the repayment of sovereign debt may not be willing or able to repay the principal and/or to pay the interest on its sovereign debt in a timely manner. A sovereign debtor’s willingness or ability to satisfy its debt obligation may be affected by various factors including, but not limited to, its cash flow situation, the extent of its foreign currency reserves, the availability of foreign exchange when a payment is due, and the relative size of its debt position in relation to its economy as a whole. In the event of default, there may be limited or no legal remedies for collecting sovereign debt and there may be no bankruptcy proceedings through which the Fund may collect all or part of the sovereign debt that a governmental entity has not repaid. Foreign Exposure Risk. The Fund may have exposure to foreign markets as a result of its investments in foreign securities, including investments in emerging markets, which can be more volatile than the U.S. markets. As a result, its returns and net asset value may be affected to a large degree by fluctuations in currency exchange rates or political or economic conditions in a particular country. In some foreign markets, there may not be protection against failure by other parties to complete transactions. It may not be possible for the Fund to repatriate capital, dividends, interest, and other income from a particular country or governmental entity. In addition, a market swing in one or more countries or regions where the Fund has invested a significant amount of its assets may have a greater effect on the Fund’s performance than it would in a more geographically diversified portfolio. To the extent the Fund invests in foreign debt securities, such investments are sensitive to changes in interest rates. Additionally, investments in securities of foreign governments involve the risk that a foreign government may not be willing or able to pay interest or repay principal when due. Real Estate Securities Risk. The Fund’s performance may be affected by the risks associated with investments in real estate-related companies. The value of real estate-related companies’ securities is sensitive to changes in real estate values and rental income, property taxes, interest rates, tax and regulatory requirements, supply and demand, and the management skill and creditworthiness of the company. Investments in REITs involve the same risks as other real estate investments. In addition, a REIT could fail to qualify for tax-free pass-through of its income under the Internal Revenue Code or fail to maintain its exemption from registration under the Investment Company Act of 1940, as amended, which could produce adverse economic consequences for the REIT and its investors, including the Fund. Inflation-Related Investment Risk. Inflation index swaps, inflation-linked bonds (including Treasury Inflation-Protected Securities (“TIPS”)), and other inflation-linked securities are subject to inflation risk. A swap held long by the Fund can potentially lose value if the rate of inflation over the life of the swap is less than the fixed rate that the Fund agrees to pay at the initiation of the swap. Except for the Fund’s investments in TIPS, which are guaranteed as to principal by the U.S. Treasury, the inflation-adjusted principal value of inflation-linked bonds repaid at maturity may be less than the original principal. Because of their inflation-linked adjustment feature, inflation-linked bonds typically have lower yields than conventional fixed-rate securities. In the event of deflation, where prices decline over time, the principal and income of inflation-linked bonds will likely decline, resulting in losses to the Fund. Commodity-Linked Investments Risk. The Fund may invest in various commodity-linked investments that provide exposure to the commodities markets. Such exposure may subject the Fund to greater volatility than investments in traditional securities. The value of a given commodity-linked derivative investment typically is based upon the price movements of a physical commodity (such as heating oil, livestock, or agricultural products), a commodity futures contract or commodity index, or some other readily measurable economic variable. The value of commodity-linked derivative instruments may therefore be affected by changes in overall market movements, volatility of the underlying benchmark, changes in interest rates, or other factors affecting a particular industry or commodity such as drought, floods, weather, livestock disease, embargoes, tariffs, and international economic, political, and regulatory developments. Derivatives Risk. Derivatives can be highly volatile and involve risks in addition to the risks of the underlying referenced securities. Gains or losses from a derivative investment can be substantially greater than the derivative’s original cost, and can therefore involve leverage. Leverage may cause the Fund to be more volatile than if it had not used leverage. Derivatives can be complex instruments and may involve analysis that differs from that required for other investment types used by the Fund. If the value of a derivative does not correlate well with the particular market or other asset class to which the derivative is intended to provide exposure, the derivative may not produce the anticipated result. Derivatives can also reduce the opportunity for gain or result in losses by offsetting positive returns in other investments. Derivatives can be less liquid than other types of investments and entail the risk that the counterparty will default on its payment obligations. If the counterparty to a derivative transaction defaults, the Fund would risk the loss of the net amount of the payments that it contractually is entitled to receive. To the extent the Fund enters into short derivative positions, the Fund may be exposed to risks similar to those associated with short sales, including the risk that the Fund’s losses are theoretically unlimited. Counterparty Risk. Certain derivative and “over-the-counter” instruments, such as swaps and forwards, are subject to the risk that the other party to a contract will not fulfill its contractual obligations. Exchange-Traded Funds Risk. The Fund may invest in ETFs, which are typically open-end investment companies that are traded on a national securities exchange. ETFs typically incur fees, such as investment advisory fees and other operating expenses that are separate from those of the Fund, which will be indirectly paid by the Fund. As a result, the cost of investing in the Fund may be higher than the cost of investing directly in ETFs and may be higher than other mutual funds that invest directly in stocks and bonds. Further, the price movement of an ETF may fluctuate against the underlying securities or commodities it tracks and may result in a loss. Because the value of ETF shares depends on the demand in the market, the Fund may not be able to purchase or sell an ETF at the most optimal time, which could adversely affect the Fund’s performance. The ETFs in which the Fund invests are subject to specific risks, depending on the investment strategy of the ETF. In turn, the Fund will be subject to substantially the same risks as those associated with direct exposure to the securities or commodities held by the ETF. Because the Fund may invest in a broad range of ETFs, such risks may include, but are not limited to, leverage risk, foreign exposure risk, and commodities risk. Mortgage-Backed Securities Risk. Mortgage-backed securities are classified generally as either commercial mortgage-backed securities or residential mortgage-backed securities, each of which is subject to certain specific risks. Mortgage-backed securities tend to be more sensitive to changes in interest rates than other types of debt securities. Investments in mortgage-backed securities are subject to both extension risk, where borrowers extend the duration of their mortgages in times of rising interest rates, and prepayment risk, where borrowers pay off their mortgages sooner than expected in times of declining interest rates. These risks may reduce the Fund’s returns. In addition, investments in mortgage-backed securities, including those comprised of subprime mortgages, may be subject to a higher degree of credit risk, valuation risk, and liquidity risk than various other types of fixed-income securities. Reverse Repurchase Agreement Risk. Reverse repurchase agreements involve leverage risk, counterparty risk, and the risk that the value of securities that the Fund is obligated to repurchase under the agreement may decline below the repurchase price. When the Fund invests reverse repurchase transaction proceeds, the Fund is at risk for any fluctuations in the value of securities in which the proceeds are invested. To the extent the Fund uses reverse repurchase agreements, the value of an investment in the Fund may be more volatile, and such transactions may increase the Fund’s overall investment exposure. Additionally, interest expenses related to reverse repurchase transactions could exceed the rate of return on debt obligations and other investments held by the Fund, thereby reducing returns to shareholders. Nondiversification Risk. The Fund is classified as nondiversified under the Investment Company Act of 1940, as amended. This gives the Fund’s portfolio managers more flexibility to hold larger positions in a smaller number of securities. As a result, an increase or decrease in the value of a single security held by the Fund may have a greater impact on the Fund’s net asset value and total return. Portfolio Turnover Risk. Increased portfolio turnover may result in higher costs, which may have a negative effect on the Fund’s performance. In addition, higher portfolio turnover may result in the acceleration of capital gains and the recognition of greater levels of short-term capital gains, which are taxed at ordinary federal income tax rates when distributed to shareholders. Securities Lending Risk. The Fund may seek to earn additional income through lending its securities to certain qualified broker-dealers and institutions. There is the risk that when portfolio securities are lent, the securities may not be returned on a timely basis, and the Fund may experience delays and costs in recovering the security or gaining access to the collateral provided to the Fund to collateralize the loan. If the Fund is unable to recover a security on loan, the Fund may use the collateral to purchase replacement securities in the market. There is a risk that the value of the collateral could decrease below the cost of the replacement security by the time the replacement investment is made, resulting in a loss to the Fund. An investment in the Fund is not a bank deposit and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency.
Risk Lose Money [Text]	rr_RiskLoseMoney	Although the Fund may be less volatile than funds that invest most of their assets in common stocks, the Fund’s returns and yields will vary, and you could lose money.
Risk Nondiversified Status [Text]	rr_RiskNondiversifiedStatus	Nondiversification Risk. The Fund is classified as nondiversified under the Investment Company Act of 1940, as amended. This gives the Fund’s portfolio managers more flexibility to hold larger positions in a smaller number of securities. As a result, an increase or decrease in the value of a single security held by the Fund may have a greater impact on the Fund’s net asset value and total return.
Risk Not Insured Depository Institution [Text]	rr_RiskNotInsuredDepositoryInstitution	An investment in the Fund is not a bank deposit and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency.
Bar Chart and Performance Table [Heading]	rr_BarChartAndPerformanceTableHeading	PERFORMANCE INFORMATION
Performance Narrative [Text Block]	rr_PerformanceNarrativeTextBlock	The following information provides some indication of the risks of investing in the Fund by showing how the Fund’s performance has varied over time. The bar chart depicts the Fund’s performance during the period indicated. The bar chart figures do not include any applicable sales charges that an investor may pay when they buy or sell Class A Shares or Class C Shares of the Fund. If sales charges were included, the returns would be lower. The table compares the Fund’s average annual returns for the periods indicated to broad-based securities market indices. The indices are not actively managed and are not available for direct investment. All figures assume reinvestment of dividends and distributions. For certain periods, the Fund’s performance reflects the effect of expense waivers. Without the effect of these expense waivers, the performance shown would have been lower. The Fund’s past performance (before and after taxes) does not necessarily indicate how it will perform in the future. Updated performance information is available at janus.com/advisor/mutual-funds or by calling 1-877-335-2687.
Performance Information Illustrates Variability of Returns [Text]	rr_PerformanceInformationIllustratesVariabilityOfReturns	The following information provides some indication of the risks of investing in the Fund by showing how the Fund’s performance has varied over time. The bar chart depicts the Fund’s performance during the period indicated.
Performance Additional Market Index [Text]	rr_PerformanceAdditionalMarketIndex	The table compares the Fund’s average annual returns for the periods indicated to broad-based securities market indices. The indices are not actively managed and are not available for direct investment. All figures assume reinvestment of dividends and distributions.
Performance Availability Phone [Text]	rr_PerformanceAvailabilityPhone	1-877-335-2687
Performance Availability Website Address [Text]	rr_PerformanceAvailabilityWebSiteAddress	janus.com/advisor/mutual-funds
Performance Past Does Not Indicate Future [Text]	rr_PerformancePastDoesNotIndicateFuture	The Fund’s past performance (before and after taxes) does not necessarily indicate how it will perform in the future.
Bar Chart [Heading]	rr_BarChartHeading	Annual Total Returns for Class I Shares (calendar year-end)
Bar Chart Does Not Reflect Sales Loads [Text]	rr_BarChartDoesNotReflectSalesLoads	The bar chart figures do not include any applicable sales charges that an investor may pay when they buy or sell Class A Shares or Class C Shares of the Fund. If sales charges were included, the returns would be lower.
Bar Chart Closing [Text Block]	rr_BarChartClosingTextBlock	Best Quarter:  First Quarter 2012  5.52%          Worst Quarter:  Second Quarter 2012  −3.72%
Year to Date Return, Label	rr_YearToDateReturnLabel	The Fund’s year-to-date return as of the calendar quarter ended September 30, 2013 was 1.36%.
Performance Table Heading	rr_PerformanceTableHeading	Average Annual Total Returns (periods ended 12/31/12)
Performance Table Uses Highest Federal Rate	rr_PerformanceTableUsesHighestFederalRate	After-tax returns are calculated using the historically highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes.
Performance Table Not Relevant to Tax Deferred	rr_PerformanceTableNotRelevantToTaxDeferred	Actual after-tax returns depend on your individual tax situation and may differ from those shown in the preceding table. The after-tax return information shown above does not apply to Fund shares held through a tax-deferred account, such as a 401(k) plan or an IRA.
Performance Table One Class of after Tax Shown [Text]	rr_PerformanceTableOneClassOfAfterTaxShown	After-tax returns are only shown for Class I Shares of the Fund. After-tax returns for the other classes of Shares will vary from those shown for Class I Shares due to varying sales charges (as applicable), fees, and expenses among the classes.
Performance Table Explanation after Tax Higher	rr_PerformanceTableExplanationAfterTaxHigher	If the Fund incurs a loss, which generates a tax benefit, the Return After Taxes on Distributions and Sale of Fund Shares may exceed the Fund’s other return figures.
Performance Table Narrative	rr_PerformanceTableNarrativeTextBlock	Effective October 15, 2012, the Fund’s primary benchmark index changed from the Barclays U.S. TIPS Index to the Barclays U.S. 1-5 Year TIPS Index. Additionally, the Fund changed its secondary benchmark index from the Consumer Price Index +400 to the Consumer Price Index +200. Janus Capital believes that the foregoing benchmark index changes provide a more appropriate representation of the Fund’s investment strategy. After-tax returns are calculated using the historically highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes. Actual after-tax returns depend on your individual tax situation and may differ from those shown in the preceding table. The after-tax return information shown above does not apply to Fund shares held through a tax-deferred account, such as a 401(k) plan or an IRA. After-tax returns are only shown for Class I Shares of the Fund. After-tax returns for the other classes of Shares will vary from those shown for Class I Shares due to varying sales charges (as applicable), fees, and expenses among the classes.
Performance Table Closing [Text Block]	rr_PerformanceTableClosingTextBlock	Updated performance information is available at janus.com/advisor/mutual-funds or by calling 1-877-335-2687.
Janus Real Return Fund | Class A, C, S, I, T Shares | Class A
Risk/Return:	rr_RiskReturnAbstract
Shareholder Fees Column [Text]	rr_ShareholderFeesColumnName	Class A
Maximum Sales Charge (load) Imposed on Purchases (as a percentage of offering price)	rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice	4.75%
Maximum Deferred Sales Charge (load) (as a percentage of the lower of original purchase price or redemption proceeds)	rr_MaximumDeferredSalesChargeOverOther	none
Operating Expenses Column [Text]	rr_OperatingExpensesColumnName	Class A
Management Fees	rr_ManagementFeesOverAssets	0.55%
Distribution/Service (12b-1) Fees	rr_DistributionAndService12b1FeesOverAssets	0.25%
Other Expenses	rr_OtherExpensesOverAssets	2.17%	[1]
Total Annual Fund Operating Expenses	rr_ExpensesOverAssets	2.97%	[2]
Fee Waiver	rr_FeeWaiverOrReimbursementOverAssets	1.96%	[2]
Total Annual Fund Operating Expenses After Fee Waiver	rr_NetExpensesOverAssets	1.01%	[2]
Expense Example, By Year, Column [Text]	rr_ExpenseExampleByYearColumnName	Class A Shares
1 Year	rr_ExpenseExampleYear01	761
3 Years	rr_ExpenseExampleYear03	1,350
5 Years	rr_ExpenseExampleYear05	1,963
10 Years	rr_ExpenseExampleYear10	3,608
Expense Example, No Redemption, By Year, Column [Text]	rr_ExpenseExampleNoRedemptionByYearColumnName	Class A Shares
1 Year	rr_ExpenseExampleNoRedemptionYear01	761
3 Years	rr_ExpenseExampleNoRedemptionYear03	1,350
5 Years	rr_ExpenseExampleNoRedemptionYear05	1,963
10 Years	rr_ExpenseExampleNoRedemptionYear10	3,608
Janus Real Return Fund | Class A, C, S, I, T Shares | Class C
Risk/Return:	rr_RiskReturnAbstract
Shareholder Fees Column [Text]	rr_ShareholderFeesColumnName	Class C
Maximum Sales Charge (load) Imposed on Purchases (as a percentage of offering price)	rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice	none
Maximum Deferred Sales Charge (load) (as a percentage of the lower of original purchase price or redemption proceeds)	rr_MaximumDeferredSalesChargeOverOther	1.00%
Operating Expenses Column [Text]	rr_OperatingExpensesColumnName	Class C
Management Fees	rr_ManagementFeesOverAssets	0.55%
Distribution/Service (12b-1) Fees	rr_DistributionAndService12b1FeesOverAssets	1.00%
Other Expenses	rr_OtherExpensesOverAssets	2.24%	[1]
Total Annual Fund Operating Expenses	rr_ExpensesOverAssets	3.79%	[2]
Fee Waiver	rr_FeeWaiverOrReimbursementOverAssets	2.03%	[2]
Total Annual Fund Operating Expenses After Fee Waiver	rr_NetExpensesOverAssets	1.76%	[2]
Expense Example, By Year, Column [Text]	rr_ExpenseExampleByYearColumnName	Class C Shares
1 Year	rr_ExpenseExampleYear01	481
3 Years	rr_ExpenseExampleYear03	1,158
5 Years	rr_ExpenseExampleYear05	1,953
10 Years	rr_ExpenseExampleYear10	4,027
Expense Example, No Redemption, By Year, Column [Text]	rr_ExpenseExampleNoRedemptionByYearColumnName	Class C Shares
1 Year	rr_ExpenseExampleNoRedemptionYear01	381
3 Years	rr_ExpenseExampleNoRedemptionYear03	1,158
5 Years	rr_ExpenseExampleNoRedemptionYear05	1,953
10 Years	rr_ExpenseExampleNoRedemptionYear10	4,027
Janus Real Return Fund | Class A, C, S, I, T Shares | Class S
Risk/Return:	rr_RiskReturnAbstract
Shareholder Fees Column [Text]	rr_ShareholderFeesColumnName	Class S
Maximum Sales Charge (load) Imposed on Purchases (as a percentage of offering price)	rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice	none
Maximum Deferred Sales Charge (load) (as a percentage of the lower of original purchase price or redemption proceeds)	rr_MaximumDeferredSalesChargeOverOther	none
Operating Expenses Column [Text]	rr_OperatingExpensesColumnName	Class S
Management Fees	rr_ManagementFeesOverAssets	0.55%
Distribution/Service (12b-1) Fees	rr_DistributionAndService12b1FeesOverAssets	0.25%
Other Expenses	rr_OtherExpensesOverAssets	2.38%	[1]
Total Annual Fund Operating Expenses	rr_ExpensesOverAssets	3.18%	[2]
Fee Waiver	rr_FeeWaiverOrReimbursementOverAssets	1.92%	[2]
Total Annual Fund Operating Expenses After Fee Waiver	rr_NetExpensesOverAssets	1.26%	[2]
Expense Example, By Year, Column [Text]	rr_ExpenseExampleByYearColumnName	Class S Shares
1 Year	rr_ExpenseExampleYear01	321
3 Years	rr_ExpenseExampleYear03	980
5 Years	rr_ExpenseExampleYear05	1,664
10 Years	rr_ExpenseExampleYear10	3,485
Expense Example, No Redemption, By Year, Column [Text]	rr_ExpenseExampleNoRedemptionByYearColumnName	Class S Shares
1 Year	rr_ExpenseExampleNoRedemptionYear01	321
3 Years	rr_ExpenseExampleNoRedemptionYear03	980
5 Years	rr_ExpenseExampleNoRedemptionYear05	1,664
10 Years	rr_ExpenseExampleNoRedemptionYear10	3,485
Janus Real Return Fund | Class A, C, S, I, T Shares | Class I
Risk/Return:	rr_RiskReturnAbstract
Shareholder Fees Column [Text]	rr_ShareholderFeesColumnName	Class I
Maximum Sales Charge (load) Imposed on Purchases (as a percentage of offering price)	rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice	none
Maximum Deferred Sales Charge (load) (as a percentage of the lower of original purchase price or redemption proceeds)	rr_MaximumDeferredSalesChargeOverOther	none
Operating Expenses Column [Text]	rr_OperatingExpensesColumnName	Class I
Management Fees	rr_ManagementFeesOverAssets	0.55%
Distribution/Service (12b-1) Fees	rr_DistributionAndService12b1FeesOverAssets	none
Other Expenses	rr_OtherExpensesOverAssets	2.15%	[1]
Total Annual Fund Operating Expenses	rr_ExpensesOverAssets	2.70%	[2]
Fee Waiver	rr_FeeWaiverOrReimbursementOverAssets	1.94%	[2]
Total Annual Fund Operating Expenses After Fee Waiver	rr_NetExpensesOverAssets	0.76%	[2]
Expense Example, By Year, Column [Text]	rr_ExpenseExampleByYearColumnName	Class I Shares
1 Year	rr_ExpenseExampleYear01	273
3 Years	rr_ExpenseExampleYear03	838
5 Years	rr_ExpenseExampleYear05	1,430
10 Years	rr_ExpenseExampleYear10	3,032
Expense Example, No Redemption, By Year, Column [Text]	rr_ExpenseExampleNoRedemptionByYearColumnName	Class I Shares
1 Year	rr_ExpenseExampleNoRedemptionYear01	273
3 Years	rr_ExpenseExampleNoRedemptionYear03	838
5 Years	rr_ExpenseExampleNoRedemptionYear05	1,430
10 Years	rr_ExpenseExampleNoRedemptionYear10	3,032
2012	rr_AnnualReturn2012	4.89%
Bar Chart, Year to Date Return, Date	rr_BarChartYearToDateReturnDate	Sep. 30, 2013
Bar Chart, Year to Date Return	rr_BarChartYearToDateReturn	1.36%
Highest Quarterly Return, Label	rr_HighestQuarterlyReturnLabel	Best Quarter:
Highest Quarterly Return, Date	rr_BarChartHighestQuarterlyReturnDate	Mar. 31, 2012
Highest Quarterly Return	rr_BarChartHighestQuarterlyReturn	5.52%
Lowest Quarterly Return, Label	rr_LowestQuarterlyReturnLabel	Worst Quarter:
Lowest Quarterly Return, Date	rr_BarChartLowestQuarterlyReturnDate	Jun. 30, 2012
Lowest Quarterly Return	rr_BarChartLowestQuarterlyReturn	(3.72%)
Janus Real Return Fund | Class A, C, S, I, T Shares | Class T
Risk/Return:	rr_RiskReturnAbstract
Shareholder Fees Column [Text]	rr_ShareholderFeesColumnName	Class T
Maximum Sales Charge (load) Imposed on Purchases (as a percentage of offering price)	rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice	none
Maximum Deferred Sales Charge (load) (as a percentage of the lower of original purchase price or redemption proceeds)	rr_MaximumDeferredSalesChargeOverOther	none
Operating Expenses Column [Text]	rr_OperatingExpensesColumnName	Class T
Management Fees	rr_ManagementFeesOverAssets	0.55%
Distribution/Service (12b-1) Fees	rr_DistributionAndService12b1FeesOverAssets	none
Other Expenses	rr_OtherExpensesOverAssets	2.38%	[1]
Total Annual Fund Operating Expenses	rr_ExpensesOverAssets	2.93%	[2]
Fee Waiver	rr_FeeWaiverOrReimbursementOverAssets	1.92%	[2]
Total Annual Fund Operating Expenses After Fee Waiver	rr_NetExpensesOverAssets	1.01%	[2]
Expense Example, By Year, Column [Text]	rr_ExpenseExampleByYearColumnName	Class T Shares
1 Year	rr_ExpenseExampleYear01	296
3 Years	rr_ExpenseExampleYear03	907
5 Years	rr_ExpenseExampleYear05	1,543
10 Years	rr_ExpenseExampleYear10	3,252
Expense Example, No Redemption, By Year, Column [Text]	rr_ExpenseExampleNoRedemptionByYearColumnName	Class T Shares
1 Year	rr_ExpenseExampleNoRedemptionYear01	296
3 Years	rr_ExpenseExampleNoRedemptionYear03	907
5 Years	rr_ExpenseExampleNoRedemptionYear05	1,543
10 Years	rr_ExpenseExampleNoRedemptionYear10	$ 3,252
Janus Real Return Fund | Class A, C, S, I, T Shares | Return Before Taxes | Class A
Risk/Return:	rr_RiskReturnAbstract
Column	rr_AverageAnnualReturnColumnName	Class A Shares
Label	rr_AverageAnnualReturnLabel	Return Before Taxes	[3]
1 Year	rr_AverageAnnualReturnYear01	(1.39%)
Since Inception	rr_AverageAnnualReturnSinceInception	(3.93%)
Inception Date	rr_AverageAnnualReturnInceptionDate	May 13, 2011
Janus Real Return Fund | Class A, C, S, I, T Shares | Return Before Taxes | Class C
Risk/Return:	rr_RiskReturnAbstract
Column	rr_AverageAnnualReturnColumnName	Class C Shares
Label	rr_AverageAnnualReturnLabel	Return Before Taxes	[4]
1 Year	rr_AverageAnnualReturnYear01	2.80%
Since Inception	rr_AverageAnnualReturnSinceInception	(1.14%)
Inception Date	rr_AverageAnnualReturnInceptionDate	May 13, 2011
Janus Real Return Fund | Class A, C, S, I, T Shares | Return Before Taxes | Class S
Risk/Return:	rr_RiskReturnAbstract
Column	rr_AverageAnnualReturnColumnName	Class S Shares
Label	rr_AverageAnnualReturnLabel	Return Before Taxes
1 Year	rr_AverageAnnualReturnYear01	4.48%
Since Inception	rr_AverageAnnualReturnSinceInception	(0.60%)
Inception Date	rr_AverageAnnualReturnInceptionDate	May 13, 2011
Janus Real Return Fund | Class A, C, S, I, T Shares | Return Before Taxes | Class I
Risk/Return:	rr_RiskReturnAbstract
Column	rr_AverageAnnualReturnColumnName	Class I Shares
Label	rr_AverageAnnualReturnLabel	Return Before Taxes
1 Year	rr_AverageAnnualReturnYear01	4.89%
Since Inception	rr_AverageAnnualReturnSinceInception	(0.12%)
Inception Date	rr_AverageAnnualReturnInceptionDate	May 13, 2011
Janus Real Return Fund | Class A, C, S, I, T Shares | Return Before Taxes | Class T
Risk/Return:	rr_RiskReturnAbstract
Column	rr_AverageAnnualReturnColumnName	Class T Shares
Label	rr_AverageAnnualReturnLabel	Return Before Taxes
1 Year	rr_AverageAnnualReturnYear01	4.67%
Since Inception	rr_AverageAnnualReturnSinceInception	(0.34%)
Inception Date	rr_AverageAnnualReturnInceptionDate	May 13, 2011
Janus Real Return Fund | Class A, C, S, I, T Shares | Return After Taxes on Distributions | Class I
Risk/Return:	rr_RiskReturnAbstract
Column	rr_AverageAnnualReturnColumnName	Class I Shares
Label	rr_AverageAnnualReturnLabel	Return After Taxes on Distributions
1 Year	rr_AverageAnnualReturnYear01	4.52%
Since Inception	rr_AverageAnnualReturnSinceInception	(0.49%)
Inception Date	rr_AverageAnnualReturnInceptionDate	May 13, 2011
Janus Real Return Fund | Class A, C, S, I, T Shares | Return After Taxes on Distributions and Sale of Fund Shares | Class I
Risk/Return:	rr_RiskReturnAbstract
Column	rr_AverageAnnualReturnColumnName	Class I Shares
Label	rr_AverageAnnualReturnLabel	Return After Taxes on Distributions and Sale of Fund Shares	[5]
1 Year	rr_AverageAnnualReturnYear01	3.40%
Since Inception	rr_AverageAnnualReturnSinceInception	(0.23%)
Inception Date	rr_AverageAnnualReturnInceptionDate	May 13, 2011
Janus Real Return Fund | Class A, C, S, I, T Shares | Barclays U.S. 1-5 Year TIPS Index (reflects no deduction for expenses, fees, or taxes)
Risk/Return:	rr_RiskReturnAbstract
Label	rr_AverageAnnualReturnLabel	Barclays U.S. 1-5 Year TIPS Index
1 Year	rr_AverageAnnualReturnYear01	2.66%
Since Inception	rr_AverageAnnualReturnSinceInception	2.44%
Inception Date	rr_AverageAnnualReturnInceptionDate	May 13, 2011
Janus Real Return Fund | Class A, C, S, I, T Shares | Consumer Price Index +200 (reflects no deduction for expenses, fees, or taxes)
Risk/Return:	rr_RiskReturnAbstract
Label	rr_AverageAnnualReturnLabel	Consumer Price Index +200
1 Year	rr_AverageAnnualReturnYear01	4.02%
Since Inception	rr_AverageAnnualReturnSinceInception	2.99%
Inception Date	rr_AverageAnnualReturnInceptionDate	May 13, 2011
Janus Real Return Fund | Class A, C, S, I, T Shares | Barclays U.S. TIPS Index (reflects no deduction for expenses, fees, or taxes)
Risk/Return:	rr_RiskReturnAbstract
Label	rr_AverageAnnualReturnLabel	Barclays U.S. TIPS Index
1 Year	rr_AverageAnnualReturnYear01	6.98%
Since Inception	rr_AverageAnnualReturnSinceInception	9.76%
Inception Date	rr_AverageAnnualReturnInceptionDate	May 13, 2011
Janus Real Return Fund | Class A, C, S, I, T Shares | Consumer Price Index +400 (reflects no deduction for expenses, fees, or taxes)
Risk/Return:	rr_RiskReturnAbstract
Label	rr_AverageAnnualReturnLabel	Consumer Price Index +400
1 Year	rr_AverageAnnualReturnYear01	6.02%
Since Inception	rr_AverageAnnualReturnSinceInception	4.97%
Inception Date	rr_AverageAnnualReturnInceptionDate	May 13, 2011

[1] Other Expenses are based on the estimated expenses that the Fund expects to incur.

[2] Janus Capital has contractually agreed to waive its investment advisory fee and/or reimburse Fund expenses to the extent that the Fund’s total annual fund operating expenses (excluding the distribution and shareholder servicing fees – applicable to Class A Shares, Class C Shares, and Class S Shares; administrative services fees payable pursuant to the Transfer Agency Agreement; brokerage commissions; interest; dividends; taxes; acquired fund fees and expenses; and extraordinary expenses) exceed 0.76% until at least November 1, 2014. The contractual waiver may be terminated or modified prior to this date only at the discretion of the Board of Trustees. For a period of three years subsequent to the Fund’s commencement of operations (May 13, 2011) or until the Fund’s assets exceed the first breakpoint in the investment advisory fee schedule that was effective at commencement of operations, whichever occurs first, Janus Capital may recover from the Fund fees and expenses previously waived or reimbursed, which could then be considered a deferral, if the Fund’s expense ratio, including recovered expenses, falls below the expense limit.

[3] Calculated assuming maximum permitted sales loads.

[4] The one year return is calculated to include the contingent deferred sales charge.

[5] If the Fund incurs a loss, which generates a tax benefit, the Return After Taxes on Distributions and Sale of Fund Shares may exceed the Fund’s other return figures.