Label	Element	Value
Risk/Return:	rr_RiskReturnAbstract
Registrant Name	dei_EntityRegistrantName	JANUS INVESTMENT FUND
Prospectus Date	rr_ProspectusDate	Oct. 28, 2016
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 99% of the average value of its portfolio.
Portfolio Turnover, Rate	rr_PortfolioTurnoverRate	99.00%
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 77 of the Fund’s Prospectus and in the “Purchases” section on page 80 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 (plus any borrowings for investment purposes) 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, 2016, the Fund’s weighted average maturity was 8.8 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, commercial 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. Additionally, 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 futures, including interest rate futures and Treasury bond futures, to manage portfolio risk and manage interest rate exposure. 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 portfolio managers additionally consider the expected risk-adjusted return on a particular investment and the Fund’s overall risk allocations and volatility. The Fund may lend portfolio securities on a short-term or long-term basis, in an amount equal to up to one-third 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. For example, while securities with longer maturities and durations tend to produce higher yields, they also tend to be more sensitive to changes in prevailing interest rates and are therefore more volatile than shorter-term securities and are subject to greater market fluctuations as a result of changes in interest rates. Further, during periods of very low or negative interest rates, the Fund may not be able to maintain positive returns. The Fund may be subject to heightened interest rate risk because the Federal Reserve has ended its monetary stimulus program known as quantitative easing and interest rates are at historically low levels. The conclusion of quantitative easing and/or rising interest rates may expose fixed-income markets to increased volatility and may reduce the liquidity of certain Fund investments. These developments could cause the Fund’s net asset value to fluctuate or make it more difficult for the Fund to accurately value its securities. These developments or others also could cause the Fund to face increased shareholder redemptions, which could force the Fund to liquidate investments at disadvantageous times or prices, therefore adversely affecting the Fund as well as the value of your investment. The amount of assets deemed illiquid remaining within the Fund may also increase, making it more difficult to meet shareholder redemptions and further adversely affecting the value of the Fund. 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. Liquidity risk may be increased to the extent that the Fund invests in Rule 144A and restricted securities. Sovereign Debt Risk.  The Fund may invest in U.S. and non-U.S. 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. In addition, to the extent the Fund invests in non-U.S. sovereign debt, it may be subject to currency risk. Mortgage- and Asset-Backed Securities Risk.  Mortgage- and asset-backed securities represent interests in “pools” of commercial or residential mortgages or other assets, including consumer loans or receivables. Mortgage- and asset-backed securities tend to be more sensitive to changes in interest rates than other types of debt securities. Investments in mortgage- and asset-backed securities are subject to both extension risk, where borrowers pay off their debt obligations more slowly in times of rising interest rates, and prepayment risk, where borrowers pay off their debt obligations sooner than expected in times of declining interest rates. These risks may reduce the Fund’s returns. In addition, investments in mortgage- and asset-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 (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. 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. Loan Risk.  The Fund may invest in a variety of loans. 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. 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. Participation interests and assignments involve credit, interest rate, and liquidity risk. 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. Management Risk.  The Fund is an actively managed investment portfolio and is therefore subject to the risk that the investment strategies employed for the Fund may fail to produce the intended results. The Fund may underperform its benchmark index or other mutual funds with similar investment objectives. 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:  3rd Quarter 2009  5.58%          Worst Quarter:  2nd Quarter 2013  – 2.10%
Year to Date Return, Label	rr_YearToDateReturnLabel	The Fund’s year-to-date return as of the calendar quarter ended September 30, 2016 was 5.32%.
Performance Table Heading	rr_PerformanceTableHeading	Average Annual Total Returns (periods ended 12/31/15)
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 Fund’s primary benchmark index is the Bloomberg Barclays U.S. Aggregate Bond Index. The index is described below. The Bloomberg Barclays U.S. Aggregate Bond Index is made up of the Bloomberg Barclays U.S. Government/Corporate Bond Index, Mortgage-Backed Securities Index, and Asset-Backed Securities Index, including securities that are of investment grade quality or better, have at least one year to maturity, and have an outstanding par value of at least $100 million. 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	0.16%
Total Annual Fund Operating Expenses	rr_ExpensesOverAssets	0.81%
Expense Example, By Year, Column [Text]	rr_ExpenseExampleByYearColumnName	Class A Shares
1 Year	rr_ExpenseExampleYear01	$ 554
3 Years	rr_ExpenseExampleYear03	721
5 Years	rr_ExpenseExampleYear05	903
10 Years	rr_ExpenseExampleYear10	$ 1,429
Expense Example, No Redemption, By Year, Column [Text]	rr_ExpenseExampleNoRedemptionByYearColumnName	Class A Shares
1 Year	rr_ExpenseExampleNoRedemptionYear01	$ 554
3 Years	rr_ExpenseExampleNoRedemptionYear03	721
5 Years	rr_ExpenseExampleNoRedemptionYear05	903
10 Years	rr_ExpenseExampleNoRedemptionYear10	$ 1,429
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	0.13%
Total Annual Fund Operating Expenses	rr_ExpensesOverAssets	1.53%
Expense Example, By Year, Column [Text]	rr_ExpenseExampleByYearColumnName	Class C Shares
1 Year	rr_ExpenseExampleYear01	$ 256
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 C Shares
1 Year	rr_ExpenseExampleNoRedemptionYear01	$ 156
3 Years	rr_ExpenseExampleNoRedemptionYear03	483
5 Years	rr_ExpenseExampleNoRedemptionYear05	834
10 Years	rr_ExpenseExampleNoRedemptionYear10	$ 1,824
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	0.29%
Total Annual Fund Operating Expenses	rr_ExpensesOverAssets	0.94%
Expense Example, By Year, Column [Text]	rr_ExpenseExampleByYearColumnName	Class S 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 S Shares
1 Year	rr_ExpenseExampleNoRedemptionYear01	$ 96
3 Years	rr_ExpenseExampleNoRedemptionYear03	300
5 Years	rr_ExpenseExampleNoRedemptionYear05	520
10 Years	rr_ExpenseExampleNoRedemptionYear10	$ 1,155
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	0.30%
Total Annual Fund Operating Expenses	rr_ExpensesOverAssets	1.20%
Expense Example, By Year, Column [Text]	rr_ExpenseExampleByYearColumnName	Class R 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 R Shares
1 Year	rr_ExpenseExampleNoRedemptionYear01	$ 122
3 Years	rr_ExpenseExampleNoRedemptionYear03	381
5 Years	rr_ExpenseExampleNoRedemptionYear05	660
10 Years	rr_ExpenseExampleNoRedemptionYear10	$ 1,455
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	0.29%
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
Expense Example, No Redemption, By Year, Column [Text]	rr_ExpenseExampleNoRedemptionByYearColumnName	Class T Shares
1 Year	rr_ExpenseExampleNoRedemptionYear01	$ 70
3 Years	rr_ExpenseExampleNoRedemptionYear03	221
5 Years	rr_ExpenseExampleNoRedemptionYear05	384
10 Years	rr_ExpenseExampleNoRedemptionYear10	$ 859
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%
2013	rr_AnnualReturn2013	(0.17%)
2014	rr_AnnualReturn2014	4.72%
2015	rr_AnnualReturn2015	0.09%
Bar Chart, Year to Date Return, Date	rr_BarChartYearToDateReturnDate	Sep. 30, 2016
Bar Chart, Year to Date Return	rr_BarChartYearToDateReturn	5.32%
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, 2013
Lowest Quarterly Return	rr_BarChartLowestQuarterlyReturn	(2.10%)
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	(4.90%)
5 Years	rr_AverageAnnualReturnYear05	2.66%
10 Years	rr_AverageAnnualReturnYear10	4.93%
Since Inception	rr_AverageAnnualReturnSinceInception	6.69%
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	(1.70%)
5 Years	rr_AverageAnnualReturnYear05	2.91%
10 Years	rr_AverageAnnualReturnYear10	4.71%
Since Inception	rr_AverageAnnualReturnSinceInception	6.19%
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	(0.17%)
5 Years	rr_AverageAnnualReturnYear05	3.50%
10 Years	rr_AverageAnnualReturnYear10	5.27%
Since Inception	rr_AverageAnnualReturnSinceInception	6.73%
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	0.11%
5 Years	rr_AverageAnnualReturnYear05	3.89%
10 Years	rr_AverageAnnualReturnYear10	5.51%
Since Inception	rr_AverageAnnualReturnSinceInception	6.90%
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	0.33%
5 Years	rr_AverageAnnualReturnYear05	3.76%
10 Years	rr_AverageAnnualReturnYear10	5.51%
Since Inception	rr_AverageAnnualReturnSinceInception	6.90%
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	(0.52%)
5 Years	rr_AverageAnnualReturnYear05	3.24%
10 Years	rr_AverageAnnualReturnYear10	5.01%
Since Inception	rr_AverageAnnualReturnSinceInception	6.47%
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	0.09%
5 Years	rr_AverageAnnualReturnYear05	3.76%
10 Years	rr_AverageAnnualReturnYear10	5.51%
Since Inception	rr_AverageAnnualReturnSinceInception	6.90%
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	(0.97%)
5 Years	rr_AverageAnnualReturnYear05	2.32%
10 Years	rr_AverageAnnualReturnYear10	3.86%
Since Inception	rr_AverageAnnualReturnSinceInception	4.46%
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	[3]
1 Year	rr_AverageAnnualReturnYear01	0.07%
5 Years	rr_AverageAnnualReturnYear05	2.39%
10 Years	rr_AverageAnnualReturnYear10	3.71%
Since Inception	rr_AverageAnnualReturnSinceInception	4.42%
Inception Date	rr_AverageAnnualReturnInceptionDate	Jul. 07, 1987
Janus Flexible Bond Fund | Class A, C, S, I, N, R, T Shares | Bloomberg Barclays U.S. Aggregate Bond Index (reflects no deduction for expenses, fees, or taxes)
Risk/Return:	rr_RiskReturnAbstract
Label	rr_AverageAnnualReturnLabel	Bloomberg Barclays U.S. Aggregate Bond Index
1 Year	rr_AverageAnnualReturnYear01	0.55%
5 Years	rr_AverageAnnualReturnYear05	3.25%
10 Years	rr_AverageAnnualReturnYear10	4.51%
Since Inception	rr_AverageAnnualReturnSinceInception	6.59%
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.

[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.