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Risk/Return:rr_RiskReturnAbstract 
Document Typedei_DocumentType485BPOS
Document Period End Datedei_DocumentPeriodEndDateJun. 30, 2011
Registrant Namedei_EntityRegistrantNameJANUS INVESTMENT FUND
Central Index Keydei_EntityCentralIndexKey0000277751
Amendment Flagdei_AmendmentFlagfalse
Document Creation Datedei_DocumentCreationDateOct. 27, 2011
Document Effective Datedei_DocumentEffectiveDateOct. 28, 2011
Prospectus Daterr_ProspectusDateOct. 28, 2011
Janus Conservative Allocation Fund | Class A, C, S, I, T Shares
 
Risk/Return:rr_RiskReturnAbstract 
Risk/Return [Heading]rr_RiskReturnHeadingFUND SUMMARY Janus Conservative Allocation Fund
Objective [Heading]rr_ObjectiveHeadingINVESTMENT OBJECTIVE
Objective, Primary [Text Block]rr_ObjectivePrimaryTextBlockJanus Conservative Allocation Fund seeks total return through a primary emphasis on income with a secondary emphasis on growth of capital.[1]
FEES AND EXPENSES OF THE FUNDjif277751_FundFeesAndExpensesAbstract 
Expense [Heading]rr_ExpenseHeadingFEES AND EXPENSES OF THE FUND
Expense Narrative [Text Block]rr_ExpenseNarrativeTextBlockThis 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.
Expense Breakpoint Discountsjif277751_ExpenseBreakpointDiscountsAbstract 
Expense Breakpoint Discounts [Text]rr_ExpenseBreakpointDiscountsFor 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 44 of the Fund’s Prospectus and in the “Purchases” section on page 64 of the Fund’s Statement of Additional Information.
Expense Breakpoint, Minimum Investment Required [Amount]rr_ExpenseBreakpointMinimumInvestmentRequiredAmount 50,000
SHAREHOLDER FEESrr_ShareholderFeesAbstract 
Shareholder Fees Caption [Text]rr_ShareholderFeesCaptionSHAREHOLDER FEES (fees paid directly from your investment)
ANNUAL FUND OPERATING EXPENSESrr_OperatingExpensesAbstract 
Operating Expenses Caption [Text]rr_OperatingExpensesCaptionANNUAL 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 Terminationrr_FeeWaiverOrReimbursementOverAssetsDateOfTerminationNovember 1, 2012
EXAMPLE:rr_ExpenseExampleAbstract 
Expense Example [Heading]rr_ExpenseExampleHeadingEXAMPLE:
Expense Example Narrative [Text Block]rr_ExpenseExampleNarrativeTextBlockThe 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 [Heading]rr_ExpenseExampleByYearHeadingThe 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) without waivers remain the same. Although your actual costs may be higher or lower, based on these assumptions your costs would be:
Expense Example by, Year, Caption [Text]rr_ExpenseExampleByYearCaptionIf Shares are redeemed:
Expense Example, No Redemption:rr_ExpenseExampleNoRedemptionAbstract 
Expense Example, No Redemption, By Year, Caption [Text]rr_ExpenseExampleNoRedemptionByYearCaptionIf Shares are not redeemed:
Portfolio Turnover:jif277751_PortfolioTurnoverAltAbstract 
Portfolio Turnover [Heading]rr_PortfolioTurnoverHeadingPortfolio Turnover:
Portfolio Turnover [Text Block]rr_PortfolioTurnoverTextBlockThe 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 period, the Fund’s portfolio turnover rate was 12% of the average value of its portfolio.
Portfolio Turnover, Raterr_PortfolioTurnoverRate12.00%
Principal Investment Strategiesjif277751_PrincipalInvestmentStrategiesAbstract 
Strategy [Heading]rr_StrategyHeadingPRINCIPAL 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. 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 40% to stocks and 60% to bonds and money market securities. 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 among stocks, bonds, and cash equivalents. The portfolio manager 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. The portfolio manager continually monitors asset class allocations and periodically rebalances the Fund’s investments in the underlying funds. 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 60% of its investments to underlying bond funds and money market instruments; and approximately 40% of its investments to underlying funds that provide varying exposure to large U.S.-based companies, small- to mid-capitalization companies, and international companies (including those with exposure to emerging markets). 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 Risksjif277751_PrincipalInvestmentRisksAbstract 
Risk [Heading]rr_RiskHeadingPRINCIPAL 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 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 Janus Capital’s allocation of assets among the underlying funds and other securities, using the optimization process 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 concentrates.

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 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 60% 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 their value 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.

Mortgage-Backed Securities Risk. Mortgage-backed securities tend to be more sensitive to changes in interest rates than other types of 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, including 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 are exposed to 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 specialized risks.

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 common stocks, 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. 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.

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 can be substantially greater than the derivative’s original cost, and can therefore involve 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. Certain underlying funds may seek to earn additional income through lending their 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 underlying fund may experience delays and costs in recovering the security or gaining access to the collateral provided to collateralize the loan. If the underlying fund is unable to recover a security on loan, the underlying 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 underlying 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_RiskLoseMoneyThe biggest risk is that the Fund’s returns will vary, and you could lose money.
Risk Not Insured Depository Institution [Text]rr_RiskNotInsuredDepositoryInstitutionAn 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 INFORMATIONjif277751_FundPastPerformanceAbstract 
Bar Chart and Performance Table [Heading]rr_BarChartAndPerformanceTableHeadingPERFORMANCE 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.

Bar Chart Does Not Reflect Sales Loads [Text]rr_BarChartDoesNotReflectSalesLoadsThe 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.
Performance Additional Market Index [Text]rr_PerformanceAdditionalMarketIndexThe 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 Past Does Not Indicate Future [Text]rr_PerformancePastDoesNotIndicateFutureThe Fund’s past performance (before and after taxes) does not necessarily indicate how it will perform in the future.
Performance Table Closing [Text Block]rr_PerformanceTableClosingTextBlockUpdated performance information is available at janus.com/advisor/mutual-funds or by calling 1-877-335-2687.
Performance Availability Website Address [Text]rr_PerformanceAvailabilityWebSiteAddressjanus.com/advisor/mutual-funds
Performance Availability Phone [Text]rr_PerformanceAvailabilityPhone1-877-335-2687
Annual Total Returnsrr_BarChartTableAbstract 
Bar Chart [Heading]rr_BarChartHeadingAnnual Total Returns for Class T 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, Labelrr_YearToDateReturnLabelThe Fund’s year-to-date return as of the calendar quarter ended September 30, 2011 was -2.59%.
Bar Chart, Year to Date Return, Daterr_BarChartYearToDateReturnDateSep. 30, 2011
Bar Chart, Year to Date Returnrr_BarChartYearToDateReturn(2.59%)
Average Annual Total Returnsrr_AverageAnnualReturnAbstract 
Captionrr_AverageAnnualReturnCaptionAverage Annual Total Returns (periods ended 12/31/10)
Performance Table Narrativerr_PerformanceTableNarrativeTextBlock

The Conservative Allocation Index is an internally-calculated, hypothetical combination of unmanaged indices that combines total returns from the Barclays Capital 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%).

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 Uses Highest Federal Raterr_PerformanceTableUsesHighestFederalRateAfter-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 Deferredrr_PerformanceTableNotRelevantToTaxDeferredActual 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_PerformanceTableOneClassOfAfterTaxShownAfter-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.
Janus Conservative Allocation Fund | Class A, C, S, I, T Shares | Class A
 
SHAREHOLDER FEESrr_ShareholderFeesAbstract 
Shareholder Fees Column [Text]rr_ShareholderFeesColumnNameClass A
Maximum Sales Charge (load) Imposed on Purchases (as a percentage of offering price)rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice5.75%
Maximum Deferred Sales Charge (load) (as a percentage of the lower of original purchase price or redemption proceeds)rr_MaximumDeferredSalesChargeOverOther none
ANNUAL FUND OPERATING EXPENSESrr_OperatingExpensesAbstract 
Operating Expenses Column [Text]rr_OperatingExpensesColumnNameClass A
Management Feesrr_ManagementFeesOverAssets0.05%
Distribution/Service (12b-1) Feesrr_DistributionAndService12b1FeesOverAssets0.25%
Other Expensesrr_OtherExpensesOverAssets0.08%
Acquired Fund Fees and Expensesrr_AcquiredFundFeesAndExpensesOverAssets0.59%
Total Annual Fund Operating Expensesrr_ExpensesOverAssets0.97%[2]
EXAMPLE:rr_ExpenseExampleAbstract 
Expense Example, By Year, Column [Text]rr_ExpenseExampleByYearColumnNameClass A Shares
1 Yearrr_ExpenseExampleYear01668
3 Yearsrr_ExpenseExampleYear03866
5 Yearsrr_ExpenseExampleYear051,080
10 Yearsrr_ExpenseExampleYear101,696
Expense Example, No Redemption:rr_ExpenseExampleNoRedemptionAbstract 
Expense Example, No Redemption, By Year, Column [Text]rr_ExpenseExampleNoRedemptionByYearColumnNameClass A Shares
1 Yearrr_ExpenseExampleNoRedemptionYear01668
3 Yearsrr_ExpenseExampleNoRedemptionYear03866
5 Yearsrr_ExpenseExampleNoRedemptionYear051,080
10 Yearsrr_ExpenseExampleNoRedemptionYear101,696
Janus Conservative Allocation Fund | Class A, C, S, I, T Shares | Class C
 
SHAREHOLDER FEESrr_ShareholderFeesAbstract 
Shareholder Fees Column [Text]rr_ShareholderFeesColumnNameClass 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_MaximumDeferredSalesChargeOverOther1.00%
ANNUAL FUND OPERATING EXPENSESrr_OperatingExpensesAbstract 
Operating Expenses Column [Text]rr_OperatingExpensesColumnNameClass C
Management Feesrr_ManagementFeesOverAssets0.05%
Distribution/Service (12b-1) Feesrr_DistributionAndService12b1FeesOverAssets1.00%
Other Expensesrr_OtherExpensesOverAssets0.09%
Acquired Fund Fees and Expensesrr_AcquiredFundFeesAndExpensesOverAssets0.59%
Total Annual Fund Operating Expensesrr_ExpensesOverAssets1.73%[2]
EXAMPLE:rr_ExpenseExampleAbstract 
Expense Example, By Year, Column [Text]rr_ExpenseExampleByYearColumnNameClass C Shares
1 Yearrr_ExpenseExampleYear01276
3 Yearsrr_ExpenseExampleYear03545
5 Yearsrr_ExpenseExampleYear05939
10 Yearsrr_ExpenseExampleYear102,041
Expense Example, No Redemption:rr_ExpenseExampleNoRedemptionAbstract 
Expense Example, No Redemption, By Year, Column [Text]rr_ExpenseExampleNoRedemptionByYearColumnNameClass C Shares
1 Yearrr_ExpenseExampleNoRedemptionYear01176
3 Yearsrr_ExpenseExampleNoRedemptionYear03545
5 Yearsrr_ExpenseExampleNoRedemptionYear05939
10 Yearsrr_ExpenseExampleNoRedemptionYear102,041
Janus Conservative Allocation Fund | Class A, C, S, I, T Shares | Class S
 
SHAREHOLDER FEESrr_ShareholderFeesAbstract 
Shareholder Fees Column [Text]rr_ShareholderFeesColumnNameClass 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
ANNUAL FUND OPERATING EXPENSESrr_OperatingExpensesAbstract 
Operating Expenses Column [Text]rr_OperatingExpensesColumnNameClass S
Management Feesrr_ManagementFeesOverAssets0.05%
Distribution/Service (12b-1) Feesrr_DistributionAndService12b1FeesOverAssets0.25%
Other Expensesrr_OtherExpensesOverAssets0.32%
Acquired Fund Fees and Expensesrr_AcquiredFundFeesAndExpensesOverAssets0.59%
Total Annual Fund Operating Expensesrr_ExpensesOverAssets1.21%[2]
EXAMPLE:rr_ExpenseExampleAbstract 
Expense Example, By Year, Column [Text]rr_ExpenseExampleByYearColumnNameClass S Shares
1 Yearrr_ExpenseExampleYear01123
3 Yearsrr_ExpenseExampleYear03384
5 Yearsrr_ExpenseExampleYear05665
10 Yearsrr_ExpenseExampleYear101,466
Expense Example, No Redemption:rr_ExpenseExampleNoRedemptionAbstract 
Expense Example, No Redemption, By Year, Column [Text]rr_ExpenseExampleNoRedemptionByYearColumnNameClass S Shares
1 Yearrr_ExpenseExampleNoRedemptionYear01123
3 Yearsrr_ExpenseExampleNoRedemptionYear03384
5 Yearsrr_ExpenseExampleNoRedemptionYear05665
10 Yearsrr_ExpenseExampleNoRedemptionYear101,466
Janus Conservative Allocation Fund | Class A, C, S, I, T Shares | Class I
 
SHAREHOLDER FEESrr_ShareholderFeesAbstract 
Shareholder Fees Column [Text]rr_ShareholderFeesColumnNameClass 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
ANNUAL FUND OPERATING EXPENSESrr_OperatingExpensesAbstract 
Operating Expenses Column [Text]rr_OperatingExpensesColumnNameClass I
Management Feesrr_ManagementFeesOverAssets0.05%
Distribution/Service (12b-1) Feesrr_DistributionAndService12b1FeesOverAssets none
Other Expensesrr_OtherExpensesOverAssets0.13%
Acquired Fund Fees and Expensesrr_AcquiredFundFeesAndExpensesOverAssets0.59%
Total Annual Fund Operating Expensesrr_ExpensesOverAssets0.77%[2]
EXAMPLE:rr_ExpenseExampleAbstract 
Expense Example, By Year, Column [Text]rr_ExpenseExampleByYearColumnNameClass I Shares
1 Yearrr_ExpenseExampleYear0179
3 Yearsrr_ExpenseExampleYear03246
5 Yearsrr_ExpenseExampleYear05428
10 Yearsrr_ExpenseExampleYear10954
Expense Example, No Redemption:rr_ExpenseExampleNoRedemptionAbstract 
Expense Example, No Redemption, By Year, Column [Text]rr_ExpenseExampleNoRedemptionByYearColumnNameClass I Shares
1 Yearrr_ExpenseExampleNoRedemptionYear0179
3 Yearsrr_ExpenseExampleNoRedemptionYear03246
5 Yearsrr_ExpenseExampleNoRedemptionYear05428
10 Yearsrr_ExpenseExampleNoRedemptionYear10954
Janus Conservative Allocation Fund | Class A, C, S, I, T Shares | Class T
 
SHAREHOLDER FEESrr_ShareholderFeesAbstract 
Shareholder Fees Column [Text]rr_ShareholderFeesColumnNameClass 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
ANNUAL FUND OPERATING EXPENSESrr_OperatingExpensesAbstract 
Operating Expenses Column [Text]rr_OperatingExpensesColumnNameClass T
Management Feesrr_ManagementFeesOverAssets0.05%
Distribution/Service (12b-1) Feesrr_DistributionAndService12b1FeesOverAssets none
Other Expensesrr_OtherExpensesOverAssets0.31%
Acquired Fund Fees and Expensesrr_AcquiredFundFeesAndExpensesOverAssets0.59%
Total Annual Fund Operating Expensesrr_ExpensesOverAssets0.95%[2]
EXAMPLE:rr_ExpenseExampleAbstract 
Expense Example, By Year, Column [Text]rr_ExpenseExampleByYearColumnNameClass T Shares
1 Yearrr_ExpenseExampleYear0197
3 Yearsrr_ExpenseExampleYear03303
5 Yearsrr_ExpenseExampleYear05525
10 Yearsrr_ExpenseExampleYear101,166
Expense Example, No Redemption:rr_ExpenseExampleNoRedemptionAbstract 
Expense Example, No Redemption, By Year, Column [Text]rr_ExpenseExampleNoRedemptionByYearColumnNameClass T Shares
1 Yearrr_ExpenseExampleNoRedemptionYear0197
3 Yearsrr_ExpenseExampleNoRedemptionYear03303
5 Yearsrr_ExpenseExampleNoRedemptionYear05525
10 Yearsrr_ExpenseExampleNoRedemptionYear101,166
Annual Total Returnsrr_BarChartTableAbstract 
2006rr_AnnualReturn200611.09%
2007rr_AnnualReturn200710.19%
2008rr_AnnualReturn2008(16.01%)
2009rr_AnnualReturn200923.37%
2010rr_AnnualReturn201010.60%
Highest Quarterly Return, Labelrr_HighestQuarterlyReturnLabelBest Quarter:
Highest Quarterly Return, Daterr_BarChartHighestQuarterlyReturnDateJun. 30, 2009
Highest Quarterly Returnrr_BarChartHighestQuarterlyReturn10.64%
Lowest Quarterly Return, Labelrr_LowestQuarterlyReturnLabelWorst Quarter:
Lowest Quarterly Return, Daterr_BarChartLowestQuarterlyReturnDateSep. 30, 2008
Lowest Quarterly Returnrr_BarChartLowestQuarterlyReturn(6.58%)
Janus Conservative Allocation Fund | Class A, C, S, I, T Shares | Return Before Taxes | Class A
 
Average Annual Total Returnsrr_AverageAnnualReturnAbstract 
Columnrr_AverageAnnualReturnColumnNameClass A Shares
Labelrr_AverageAnnualReturnLabelReturn Before Taxes[3]
1 Yearrr_AverageAnnualReturnYear014.19%
5 Yearsrr_AverageAnnualReturnYear055.53%
Since Inceptionrr_AverageAnnualReturnSinceInception5.52%
Inception Daterr_AverageAnnualReturnInceptionDateDec. 30, 2005
Janus Conservative Allocation Fund | Class A, C, S, I, T Shares | Return Before Taxes | Class C
 
Average Annual Total Returnsrr_AverageAnnualReturnAbstract 
Columnrr_AverageAnnualReturnColumnNameClass C Shares
Labelrr_AverageAnnualReturnLabelReturn Before Taxes[4]
1 Yearrr_AverageAnnualReturnYear018.58%
5 Yearsrr_AverageAnnualReturnYear056.00%
Since Inceptionrr_AverageAnnualReturnSinceInception6.00%
Inception Daterr_AverageAnnualReturnInceptionDateDec. 30, 2005
Janus Conservative Allocation Fund | Class A, C, S, I, T Shares | Return Before Taxes | Class S
 
Average Annual Total Returnsrr_AverageAnnualReturnAbstract 
Columnrr_AverageAnnualReturnColumnNameClass S Shares
Labelrr_AverageAnnualReturnLabelReturn Before Taxes
1 Yearrr_AverageAnnualReturnYear0110.35%
5 Yearsrr_AverageAnnualReturnYear056.51%
Since Inceptionrr_AverageAnnualReturnSinceInception6.51%
Inception Daterr_AverageAnnualReturnInceptionDateDec. 30, 2005
Janus Conservative Allocation Fund | Class A, C, S, I, T Shares | Return Before Taxes | Class I
 
Average Annual Total Returnsrr_AverageAnnualReturnAbstract 
Columnrr_AverageAnnualReturnColumnNameClass I Shares
Labelrr_AverageAnnualReturnLabelReturn Before Taxes
1 Yearrr_AverageAnnualReturnYear0110.79%
5 Yearsrr_AverageAnnualReturnYear057.00%
Since Inceptionrr_AverageAnnualReturnSinceInception7.00%
Inception Daterr_AverageAnnualReturnInceptionDateDec. 30, 2005
Janus Conservative Allocation Fund | Class A, C, S, I, T Shares | Return Before Taxes | Class T
 
Average Annual Total Returnsrr_AverageAnnualReturnAbstract 
Columnrr_AverageAnnualReturnColumnNameClass T Shares
Labelrr_AverageAnnualReturnLabelReturn Before Taxes
1 Yearrr_AverageAnnualReturnYear0110.60%
5 Yearsrr_AverageAnnualReturnYear057.00%
Since Inceptionrr_AverageAnnualReturnSinceInception7.00%
Inception Daterr_AverageAnnualReturnInceptionDateDec. 30, 2005
Janus Conservative Allocation Fund | Class A, C, S, I, T Shares | Return After Taxes on Distributions | Class T
 
Average Annual Total Returnsrr_AverageAnnualReturnAbstract 
Columnrr_AverageAnnualReturnColumnNameClass T Shares
Labelrr_AverageAnnualReturnLabelReturn After Taxes on Distributions
1 Yearrr_AverageAnnualReturnYear019.36%
5 Yearsrr_AverageAnnualReturnYear055.94%
Since Inceptionrr_AverageAnnualReturnSinceInception5.94%
Inception Daterr_AverageAnnualReturnInceptionDateDec. 30, 2005
Janus Conservative Allocation Fund | Class A, C, S, I, T Shares | Return After Taxes on Distributions and Sale of Fund Shares | Class T
 
Average Annual Total Returnsrr_AverageAnnualReturnAbstract 
Columnrr_AverageAnnualReturnColumnNameClass T Shares
Labelrr_AverageAnnualReturnLabelReturn After Taxes on Distributions and Sale of Fund Shares[5]
1 Yearrr_AverageAnnualReturnYear016.96%
5 Yearsrr_AverageAnnualReturnYear055.44%
Since Inceptionrr_AverageAnnualReturnSinceInception5.44%
Inception Daterr_AverageAnnualReturnInceptionDateDec. 30, 2005
Janus Conservative Allocation Fund | Class A, C, S, I, T Shares | S&P 500® Index
 
Average Annual Total Returnsrr_AverageAnnualReturnAbstract 
Labelrr_AverageAnnualReturnLabelS&P 500® Index
Index No Deduction for Fees, Expenses, Taxes [Text]rr_IndexNoDeductionForFeesExpensesTaxes(reflects no deduction for expenses, fees, or taxes)
1 Yearrr_AverageAnnualReturnYear0115.06%
5 Yearsrr_AverageAnnualReturnYear052.29%
Since Inceptionrr_AverageAnnualReturnSinceInception2.29%
Inception Daterr_AverageAnnualReturnInceptionDateDec. 30, 2005
Janus Conservative Allocation Fund | Class A, C, S, I, T Shares | Conservative Allocation Index
 
Average Annual Total Returnsrr_AverageAnnualReturnAbstract 
Labelrr_AverageAnnualReturnLabelConservative Allocation Index
Index No Deduction for Fees, Expenses, Taxes [Text]rr_IndexNoDeductionForFeesExpensesTaxes(reflects no deduction for expenses, fees, or taxes)
1 Yearrr_AverageAnnualReturnYear0110.38%
5 Yearsrr_AverageAnnualReturnYear055.15%
Since Inceptionrr_AverageAnnualReturnSinceInception5.14%
Inception Daterr_AverageAnnualReturnInceptionDateDec. 30, 2005
Janus Conservative Allocation Fund | Class D Shares
 
Risk/Return:rr_RiskReturnAbstract 
Risk/Return [Heading]rr_RiskReturnHeadingFUND SUMMARY Janus Conservative Allocation Fund
Objective [Heading]rr_ObjectiveHeadingINVESTMENT OBJECTIVE
Objective, Primary [Text Block]rr_ObjectivePrimaryTextBlockJanus Conservative Allocation Fund seeks total return through a primary emphasis on income with a secondary emphasis on growth of capital.[1]
FEES AND EXPENSES OF THE FUNDjif277751_FundFeesAndExpensesAbstract 
Expense [Heading]rr_ExpenseHeadingFEES AND EXPENSES OF THE FUND
Expense Narrative [Text Block]rr_ExpenseNarrativeTextBlockThis table describes the fees and expenses that you may pay if you buy and hold Shares of the Fund.
ANNUAL FUND OPERATING EXPENSESrr_OperatingExpensesAbstract 
Operating Expenses Caption [Text]rr_OperatingExpensesCaptionANNUAL 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 Terminationrr_FeeWaiverOrReimbursementOverAssetsDateOfTerminationNovember 1, 2012
EXAMPLE:rr_ExpenseExampleAbstract 
Expense Example [Heading]rr_ExpenseExampleHeadingEXAMPLE:
Expense Example Narrative [Text Block]rr_ExpenseExampleNarrativeTextBlockThe 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 [Heading]rr_ExpenseExampleByYearHeadingThe 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) without waivers remain the same. Although your actual costs may be higher or lower, based on these assumptions your costs would be:
Portfolio Turnover:jif277751_PortfolioTurnoverAltAbstract 
Portfolio Turnover [Heading]rr_PortfolioTurnoverHeadingPortfolio Turnover:
Portfolio Turnover [Text Block]rr_PortfolioTurnoverTextBlockThe 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 period, the Fund’s portfolio turnover rate was 12% of the average value of its portfolio.
Portfolio Turnover, Raterr_PortfolioTurnoverRate12.00%
Principal Investment Strategiesjif277751_PrincipalInvestmentStrategiesAbstract 
Strategy [Heading]rr_StrategyHeadingPRINCIPAL 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. 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 40% to stocks and 60% to bonds and money market securities. 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 among stocks, bonds, and cash equivalents. The portfolio manager 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. The portfolio manager continually monitors asset class allocations and periodically rebalances the Fund’s investments in the underlying funds. 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 60% of its investments to underlying bond funds and money market instruments; and approximately 40% of its investments to underlying funds that provide varying exposure to large U.S.-based companies, small- to mid-capitalization companies, and international companies (including those with exposure to emerging markets). 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 Risksjif277751_PrincipalInvestmentRisksAbstract 
Risk [Heading]rr_RiskHeadingPRINCIPAL 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 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 Janus Capital’s allocation of assets among the underlying funds and other securities, using the optimization process 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 concentrates.

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 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 60% 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 their value 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.

Mortgage-Backed Securities Risk. Mortgage-backed securities tend to be more sensitive to changes in interest rates than other types of 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, including 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 are exposed to 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 specialized risks.

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 common stocks, 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. 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.

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 can be substantially greater than the derivative’s original cost, and can therefore involve 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. Certain underlying funds may seek to earn additional income through lending their 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 underlying fund may experience delays and costs in recovering the security or gaining access to the collateral provided to collateralize the loan. If the underlying fund is unable to recover a security on loan, the underlying 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 underlying 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_RiskLoseMoneyThe biggest risk is that the Fund’s returns will vary, and you could lose money.
Risk Not Insured Depository Institution [Text]rr_RiskNotInsuredDepositoryInstitutionAn 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 INFORMATIONjif277751_FundPastPerformanceAbstract 
Bar Chart and Performance Table [Heading]rr_BarChartAndPerformanceTableHeadingPERFORMANCE 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_PerformanceAdditionalMarketIndexThe 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 Past Does Not Indicate Future [Text]rr_PerformancePastDoesNotIndicateFutureThe Fund’s past performance (before and after taxes) does not necessarily indicate how it will perform in the future.
Performance Table Closing [Text Block]rr_PerformanceTableClosingTextBlockUpdated performance information is available at janus.com/allfunds or by calling 1-800-525-3713.
Performance Availability Website Address [Text]rr_PerformanceAvailabilityWebSiteAddressjanus.com/allfunds
Performance Availability Phone [Text]rr_PerformanceAvailabilityPhone1-800-525-3713
Annual Total Returnsrr_BarChartTableAbstract 
Bar Chart [Heading]rr_BarChartHeadingAnnual 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, Labelrr_YearToDateReturnLabelThe Fund’s year-to-date return as of the calendar quarter ended September 30, 2011 was -2.50%.
Bar Chart, Year to Date Return, Daterr_BarChartYearToDateReturnDateSep. 30, 2011
Bar Chart, Year to Date Returnrr_BarChartYearToDateReturn(2.50%)
Average Annual Total Returnsrr_AverageAnnualReturnAbstract 
Captionrr_AverageAnnualReturnCaptionAverage Annual Total Returns (periods ended 12/31/10)
Performance Table Narrativerr_PerformanceTableNarrativeTextBlock

The Conservative Allocation Index is an internally-calculated, hypothetical combination of unmanaged indices that combines total returns from the Barclays Capital 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%).

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 Uses Highest Federal Raterr_PerformanceTableUsesHighestFederalRateAfter-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 Deferredrr_PerformanceTableNotRelevantToTaxDeferredActual 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.
Janus Conservative Allocation Fund | Class D Shares | Class D
 
ANNUAL FUND OPERATING EXPENSESrr_OperatingExpensesAbstract 
Operating Expenses Column [Text]rr_OperatingExpensesColumnNameClass D
Management Feesrr_ManagementFeesOverAssets0.05%
Other Expensesrr_OtherExpensesOverAssets0.20%
Acquired Fund Fees and Expensesrr_AcquiredFundFeesAndExpensesOverAssets0.59%
Total Annual Fund Operating Expensesrr_ExpensesOverAssets0.84%[6]
EXAMPLE:rr_ExpenseExampleAbstract 
Expense Example, By Year, Column [Text]rr_ExpenseExampleByYearColumnNameClass D Shares
1 Yearrr_ExpenseExampleYear0186
3 Yearsrr_ExpenseExampleYear03268
5 Yearsrr_ExpenseExampleYear05466
10 Yearsrr_ExpenseExampleYear101,037
Annual Total Returnsrr_BarChartTableAbstract 
2006rr_AnnualReturn200611.09%
2007rr_AnnualReturn200710.19%
2008rr_AnnualReturn2008(16.01%)
2009rr_AnnualReturn200923.37%
2010rr_AnnualReturn201010.69%
Highest Quarterly Return, Labelrr_HighestQuarterlyReturnLabelBest Quarter:
Highest Quarterly Return, Daterr_BarChartHighestQuarterlyReturnDateJun. 30, 2009
Highest Quarterly Returnrr_BarChartHighestQuarterlyReturn10.64%
Lowest Quarterly Return, Labelrr_LowestQuarterlyReturnLabelWorst Quarter:
Lowest Quarterly Return, Daterr_BarChartLowestQuarterlyReturnDateSep. 30, 2008
Lowest Quarterly Returnrr_BarChartLowestQuarterlyReturn(6.58%)
Janus Conservative Allocation Fund | Class D Shares | Return Before Taxes | Class D
 
Average Annual Total Returnsrr_AverageAnnualReturnAbstract 
Columnrr_AverageAnnualReturnColumnNameClass D Shares
Labelrr_AverageAnnualReturnLabelReturn Before Taxes
1 Yearrr_AverageAnnualReturnYear0110.69%
5 Yearsrr_AverageAnnualReturnYear057.02%
Since Inceptionrr_AverageAnnualReturnSinceInception7.02%
Inception Daterr_AverageAnnualReturnInceptionDateDec. 30, 2005
Janus Conservative Allocation Fund | Class D Shares | Return After Taxes on Distributions | Class D
 
Average Annual Total Returnsrr_AverageAnnualReturnAbstract 
Columnrr_AverageAnnualReturnColumnNameClass D Shares
Labelrr_AverageAnnualReturnLabelReturn After Taxes on Distributions
1 Yearrr_AverageAnnualReturnYear019.43%
5 Yearsrr_AverageAnnualReturnYear055.96%
Since Inceptionrr_AverageAnnualReturnSinceInception5.95%
Inception Daterr_AverageAnnualReturnInceptionDateDec. 30, 2005
Janus Conservative Allocation Fund | Class D Shares | Return After Taxes on Distributions and Sale of Fund Shares | Class D
 
Average Annual Total Returnsrr_AverageAnnualReturnAbstract 
Columnrr_AverageAnnualReturnColumnNameClass D Shares
Labelrr_AverageAnnualReturnLabelReturn After Taxes on Distributions and Sale of Fund Shares[5]
1 Yearrr_AverageAnnualReturnYear017.02%
5 Yearsrr_AverageAnnualReturnYear055.45%
Since Inceptionrr_AverageAnnualReturnSinceInception5.45%
Inception Daterr_AverageAnnualReturnInceptionDateDec. 30, 2005
Janus Conservative Allocation Fund | Class D Shares | S&P 500® Index
 
Average Annual Total Returnsrr_AverageAnnualReturnAbstract 
Labelrr_AverageAnnualReturnLabelS&P 500® Index
Index No Deduction for Fees, Expenses, Taxes [Text]rr_IndexNoDeductionForFeesExpensesTaxes(reflects no deduction for expenses, fees, or taxes)
1 Yearrr_AverageAnnualReturnYear0115.06%
5 Yearsrr_AverageAnnualReturnYear052.29%
Since Inceptionrr_AverageAnnualReturnSinceInception2.29%
Inception Daterr_AverageAnnualReturnInceptionDateDec. 30, 2005
Janus Conservative Allocation Fund | Class D Shares | Conservative Allocation Index
 
Average Annual Total Returnsrr_AverageAnnualReturnAbstract 
Labelrr_AverageAnnualReturnLabelConservative Allocation Index
Index No Deduction for Fees, Expenses, Taxes [Text]rr_IndexNoDeductionForFeesExpensesTaxes(reflects no deduction for expenses, fees, or taxes)
1 Yearrr_AverageAnnualReturnYear0110.38%
5 Yearsrr_AverageAnnualReturnYear055.15%
Since Inceptionrr_AverageAnnualReturnSinceInception5.14%
Inception Daterr_AverageAnnualReturnInceptionDateDec. 30, 2005
Janus Moderate Allocation Fund | Class A, C, S, I, T Shares
 
Risk/Return:rr_RiskReturnAbstract 
Risk/Return [Heading]rr_RiskReturnHeadingFUND SUMMARY Janus Moderate Allocation Fund
Objective [Heading]rr_ObjectiveHeadingINVESTMENT OBJECTIVE
Objective, Primary [Text Block]rr_ObjectivePrimaryTextBlockJanus Moderate Allocation Fund seeks total return through growth of capital and income.[1]
FEES AND EXPENSES OF THE FUNDjif277751_FundFeesAndExpensesAbstract 
Expense [Heading]rr_ExpenseHeadingFEES AND EXPENSES OF THE FUND
Expense Narrative [Text Block]rr_ExpenseNarrativeTextBlockThis 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.
Expense Breakpoint Discountsjif277751_ExpenseBreakpointDiscountsAbstract 
Expense Breakpoint Discounts [Text]rr_ExpenseBreakpointDiscountsFor 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 44 of the Fund’s Prospectus and in the “Purchases” section on page 64 of the Fund’s Statement of Additional Information.
Expense Breakpoint, Minimum Investment Required [Amount]rr_ExpenseBreakpointMinimumInvestmentRequiredAmount50,000
SHAREHOLDER FEESrr_ShareholderFeesAbstract 
Shareholder Fees Caption [Text]rr_ShareholderFeesCaptionSHAREHOLDER FEES (fees paid directly from your investment)
ANNUAL FUND OPERATING EXPENSESrr_OperatingExpensesAbstract 
Operating Expenses Caption [Text]rr_OperatingExpensesCaptionANNUAL 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 Terminationrr_FeeWaiverOrReimbursementOverAssetsDateOfTerminationNovember 1, 2012
EXAMPLE:rr_ExpenseExampleAbstract 
Expense Example [Heading]rr_ExpenseExampleHeadingEXAMPLE:
Expense Example Narrative [Text Block]rr_ExpenseExampleNarrativeTextBlockThe 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 [Heading]rr_ExpenseExampleByYearHeadingThe 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) without waivers remain the same. Although your actual costs may be higher or lower, based on these assumptions your costs would be:
Expense Example by, Year, Caption [Text]rr_ExpenseExampleByYearCaptionIf Shares are redeemed:
Expense Example, No Redemption:rr_ExpenseExampleNoRedemptionAbstract 
Expense Example, No Redemption, By Year, Caption [Text]rr_ExpenseExampleNoRedemptionByYearCaptionIf Shares are not redeemed:
Portfolio Turnover:jif277751_PortfolioTurnoverAltAbstract 
Portfolio Turnover [Heading]rr_PortfolioTurnoverHeadingPortfolio Turnover:
Portfolio Turnover [Text Block]rr_PortfolioTurnoverTextBlockThe 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 period, the Fund’s portfolio turnover rate was 15% of the average value of its portfolio.
Portfolio Turnover, Raterr_PortfolioTurnoverRate15.00%
Principal Investment Strategiesjif277751_PrincipalInvestmentStrategiesAbstract 
Strategy [Heading]rr_StrategyHeadingPRINCIPAL 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. 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 60% to stocks and 40% to bonds and money market securities. 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 among stocks, bonds, and cash equivalents. The portfolio manager 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. The portfolio manager continually monitors asset class allocations and periodically rebalances the Fund’s investments in the underlying funds. 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 60% of its investments to underlying funds that provide varying exposure to large U.S.-based companies, small- to mid-capitalization companies, and international companies (including those with exposure to emerging markets); and approximately 40% of its investments to underlying bond funds and money market instruments. 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 Risksjif277751_PrincipalInvestmentRisksAbstract 
Risk [Heading]rr_RiskHeadingPRINCIPAL 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 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 Janus Capital’s allocation of assets among the underlying funds and other securities, using the optimization process 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 concentrates.

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 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 60% 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 40% 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 their value 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.

Foreign Exposure Risk. Certain underlying funds may have significant exposure to foreign markets, including 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 are exposed to 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 specialized risks.

Mortgage-Backed Securities Risk. Mortgage-backed securities tend to be more sensitive to changes in interest rates than other types of 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.

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 common stocks, 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. 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.

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 can be substantially greater than the derivative’s original cost, and can therefore involve 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. Certain underlying funds may seek to earn additional income through lending their 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 underlying fund may experience delays and costs in recovering the security or gaining access to the collateral provided to collateralize the loan. If the underlying fund is unable to recover a security on loan, the underlying 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 underlying 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_RiskLoseMoneyThe biggest risk is that the Fund’s returns will vary, and you could lose money.
Risk Not Insured Depository Institution [Text]rr_RiskNotInsuredDepositoryInstitutionAn 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 INFORMATIONjif277751_FundPastPerformanceAbstract 
Bar Chart and Performance Table [Heading]rr_BarChartAndPerformanceTableHeadingPERFORMANCE 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, 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.

Bar Chart Does Not Reflect Sales Loads [Text]rr_BarChartDoesNotReflectSalesLoadsThe 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.
Performance Additional Market Index [Text]rr_PerformanceAdditionalMarketIndexThe 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 Past Does Not Indicate Future [Text]rr_PerformancePastDoesNotIndicateFutureThe Fund’s past performance (before and after taxes) does not necessarily indicate how it will perform in the future.
Performance Table Closing [Text Block]rr_PerformanceTableClosingTextBlockUpdated performance information is available at janus.com/advisor/mutual-funds or by calling 1-877-335-2687.
Performance Availability Website Address [Text]rr_PerformanceAvailabilityWebSiteAddressjanus.com/advisor/mutual-funds
Performance Availability Phone [Text]rr_PerformanceAvailabilityPhone1-877-335-2687
Annual Total Returnsrr_BarChartTableAbstract 
Bar Chart [Heading]rr_BarChartHeadingAnnual Total Returns for Class T 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, Labelrr_YearToDateReturnLabelThe Fund’s year-to-date return as of the calendar quarter ended September 30, 2011 was -7.53%.
Bar Chart, Year to Date Return, Daterr_BarChartYearToDateReturnDateSep. 30, 2011
Bar Chart, Year to Date Returnrr_BarChartYearToDateReturn(7.53%)
Average Annual Total Returnsrr_AverageAnnualReturnAbstract 
Captionrr_AverageAnnualReturnCaptionAverage Annual Total Returns (periods ended 12/31/10)
Performance Table Narrativerr_PerformanceTableNarrativeTextBlock

The Moderate Allocation Index is an internally-calculated, hypothetical combination of unmanaged indices that combines total returns from the Dow Jones Wilshire 5000 Index (40%), the Barclays Capital U.S. Aggregate Bond Index (40%), the MSCI EAFE® Index (18%), and the Morgan Stanley Capital International Emerging Markets Free IndexSM (2%).

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 Uses Highest Federal Raterr_PerformanceTableUsesHighestFederalRateAfter-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 Deferredrr_PerformanceTableNotRelevantToTaxDeferredActual 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_PerformanceTableOneClassOfAfterTaxShownAfter-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.
Janus Moderate Allocation Fund | Class A, C, S, I, T Shares | Class A
 
SHAREHOLDER FEESrr_ShareholderFeesAbstract 
Shareholder Fees Column [Text]rr_ShareholderFeesColumnNameClass A
Maximum Sales Charge (load) Imposed on Purchases (as a percentage of offering price)rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice5.75%
Maximum Deferred Sales Charge (load) (as a percentage of the lower of original purchase price or redemption proceeds)rr_MaximumDeferredSalesChargeOverOther none
ANNUAL FUND OPERATING EXPENSESrr_OperatingExpensesAbstract 
Operating Expenses Column [Text]rr_OperatingExpensesColumnNameClass A
Management Feesrr_ManagementFeesOverAssets0.05%
Distribution/Service (12b-1) Feesrr_DistributionAndService12b1FeesOverAssets0.25%
Other Expensesrr_OtherExpensesOverAssets0.20%
Acquired Fund Fees and Expensesrr_AcquiredFundFeesAndExpensesOverAssets0.63%
Total Annual Fund Operating Expensesrr_ExpensesOverAssets1.13%[7]
EXAMPLE:rr_ExpenseExampleAbstract 
Expense Example, By Year, Column [Text]rr_ExpenseExampleByYearColumnNameClass A Shares
1 Yearrr_ExpenseExampleYear01684
3 Yearsrr_ExpenseExampleYear03913
5 Yearsrr_ExpenseExampleYear051,161
10 Yearsrr_ExpenseExampleYear101,871
Expense Example, No Redemption:rr_ExpenseExampleNoRedemptionAbstract 
Expense Example, No Redemption, By Year, Column [Text]rr_ExpenseExampleNoRedemptionByYearColumnNameClass A Shares
1 Yearrr_ExpenseExampleNoRedemptionYear01684
3 Yearsrr_ExpenseExampleNoRedemptionYear03913
5 Yearsrr_ExpenseExampleNoRedemptionYear051,161
10 Yearsrr_ExpenseExampleNoRedemptionYear101,871
Janus Moderate Allocation Fund | Class A, C, S, I, T Shares | Class C
 
SHAREHOLDER FEESrr_ShareholderFeesAbstract 
Shareholder Fees Column [Text]rr_ShareholderFeesColumnNameClass 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_MaximumDeferredSalesChargeOverOther1.00%
ANNUAL FUND OPERATING EXPENSESrr_OperatingExpensesAbstract 
Operating Expenses Column [Text]rr_OperatingExpensesColumnNameClass C
Management Feesrr_ManagementFeesOverAssets0.05%
Distribution/Service (12b-1) Feesrr_DistributionAndService12b1FeesOverAssets1.00%
Other Expensesrr_OtherExpensesOverAssets0.11%
Acquired Fund Fees and Expensesrr_AcquiredFundFeesAndExpensesOverAssets0.63%
Total Annual Fund Operating Expensesrr_ExpensesOverAssets1.79%[7]
EXAMPLE:rr_ExpenseExampleAbstract 
Expense Example, By Year, Column [Text]rr_ExpenseExampleByYearColumnNameClass C Shares
1 Yearrr_ExpenseExampleYear01282
3 Yearsrr_ExpenseExampleYear03563
5 Yearsrr_ExpenseExampleYear05970
10 Yearsrr_ExpenseExampleYear102,105
Expense Example, No Redemption:rr_ExpenseExampleNoRedemptionAbstract 
Expense Example, No Redemption, By Year, Column [Text]rr_ExpenseExampleNoRedemptionByYearColumnNameClass C Shares
1 Yearrr_ExpenseExampleNoRedemptionYear01182
3 Yearsrr_ExpenseExampleNoRedemptionYear03563
5 Yearsrr_ExpenseExampleNoRedemptionYear05970
10 Yearsrr_ExpenseExampleNoRedemptionYear102,105
Janus Moderate Allocation Fund | Class A, C, S, I, T Shares | Class S
 
SHAREHOLDER FEESrr_ShareholderFeesAbstract 
Shareholder Fees Column [Text]rr_ShareholderFeesColumnNameClass 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
ANNUAL FUND OPERATING EXPENSESrr_OperatingExpensesAbstract 
Operating Expenses Column [Text]rr_OperatingExpensesColumnNameClass S
Management Feesrr_ManagementFeesOverAssets0.05%
Distribution/Service (12b-1) Feesrr_DistributionAndService12b1FeesOverAssets0.25%
Other Expensesrr_OtherExpensesOverAssets0.34%
Acquired Fund Fees and Expensesrr_AcquiredFundFeesAndExpensesOverAssets0.63%
Total Annual Fund Operating Expensesrr_ExpensesOverAssets1.27%[7]
EXAMPLE:rr_ExpenseExampleAbstract 
Expense Example, By Year, Column [Text]rr_ExpenseExampleByYearColumnNameClass S Shares
1 Yearrr_ExpenseExampleYear01129
3 Yearsrr_ExpenseExampleYear03403
5 Yearsrr_ExpenseExampleYear05697
10 Yearsrr_ExpenseExampleYear101,534
Expense Example, No Redemption:rr_ExpenseExampleNoRedemptionAbstract 
Expense Example, No Redemption, By Year, Column [Text]rr_ExpenseExampleNoRedemptionByYearColumnNameClass S Shares
1 Yearrr_ExpenseExampleNoRedemptionYear01129
3 Yearsrr_ExpenseExampleNoRedemptionYear03403
5 Yearsrr_ExpenseExampleNoRedemptionYear05697
10 Yearsrr_ExpenseExampleNoRedemptionYear101,534
Janus Moderate Allocation Fund | Class A, C, S, I, T Shares | Class I
 
SHAREHOLDER FEESrr_ShareholderFeesAbstract 
Shareholder Fees Column [Text]rr_ShareholderFeesColumnNameClass 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
ANNUAL FUND OPERATING EXPENSESrr_OperatingExpensesAbstract 
Operating Expenses Column [Text]rr_OperatingExpensesColumnNameClass I
Management Feesrr_ManagementFeesOverAssets0.05%
Distribution/Service (12b-1) Feesrr_DistributionAndService12b1FeesOverAssets none
Other Expensesrr_OtherExpensesOverAssets0.12%
Acquired Fund Fees and Expensesrr_AcquiredFundFeesAndExpensesOverAssets0.63%
Total Annual Fund Operating Expensesrr_ExpensesOverAssets0.80%[7]
EXAMPLE:rr_ExpenseExampleAbstract 
Expense Example, By Year, Column [Text]rr_ExpenseExampleByYearColumnNameClass I Shares
1 Yearrr_ExpenseExampleYear0182
3 Yearsrr_ExpenseExampleYear03255
5 Yearsrr_ExpenseExampleYear05444
10 Yearsrr_ExpenseExampleYear10990
Expense Example, No Redemption:rr_ExpenseExampleNoRedemptionAbstract 
Expense Example, No Redemption, By Year, Column [Text]rr_ExpenseExampleNoRedemptionByYearColumnNameClass I Shares
1 Yearrr_ExpenseExampleNoRedemptionYear0182
3 Yearsrr_ExpenseExampleNoRedemptionYear03255
5 Yearsrr_ExpenseExampleNoRedemptionYear05444
10 Yearsrr_ExpenseExampleNoRedemptionYear10990
Janus Moderate Allocation Fund | Class A, C, S, I, T Shares | Class T
 
SHAREHOLDER FEESrr_ShareholderFeesAbstract 
Shareholder Fees Column [Text]rr_ShareholderFeesColumnNameClass 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
ANNUAL FUND OPERATING EXPENSESrr_OperatingExpensesAbstract 
Operating Expenses Column [Text]rr_OperatingExpensesColumnNameClass T
Management Feesrr_ManagementFeesOverAssets0.05%
Distribution/Service (12b-1) Feesrr_DistributionAndService12b1FeesOverAssets none
Other Expensesrr_OtherExpensesOverAssets0.30%
Acquired Fund Fees and Expensesrr_AcquiredFundFeesAndExpensesOverAssets0.63%
Total Annual Fund Operating Expensesrr_ExpensesOverAssets0.98%[7]
EXAMPLE:rr_ExpenseExampleAbstract 
Expense Example, By Year, Column [Text]rr_ExpenseExampleByYearColumnNameClass T Shares
1 Yearrr_ExpenseExampleYear01100
3 Yearsrr_ExpenseExampleYear03312
5 Yearsrr_ExpenseExampleYear05542
10 Yearsrr_ExpenseExampleYear101,201
Expense Example, No Redemption:rr_ExpenseExampleNoRedemptionAbstract 
Expense Example, No Redemption, By Year, Column [Text]rr_ExpenseExampleNoRedemptionByYearColumnNameClass T Shares
1 Yearrr_ExpenseExampleNoRedemptionYear01100
3 Yearsrr_ExpenseExampleNoRedemptionYear03312
5 Yearsrr_ExpenseExampleNoRedemptionYear05542
10 Yearsrr_ExpenseExampleNoRedemptionYear101,201
Annual Total Returnsrr_BarChartTableAbstract 
2006rr_AnnualReturn200614.28%
2007rr_AnnualReturn200712.71%
2008rr_AnnualReturn2008(25.28%)
2009rr_AnnualReturn200930.34%
2010rr_AnnualReturn201012.19%
Highest Quarterly Return, Labelrr_HighestQuarterlyReturnLabelBest Quarter:
Highest Quarterly Return, Daterr_BarChartHighestQuarterlyReturnDateJun. 30, 2009
Highest Quarterly Returnrr_BarChartHighestQuarterlyReturn14.27%
Lowest Quarterly Return, Labelrr_LowestQuarterlyReturnLabelWorst Quarter:
Lowest Quarterly Return, Daterr_BarChartLowestQuarterlyReturnDateDec. 31, 2008
Lowest Quarterly Returnrr_BarChartLowestQuarterlyReturn(11.62%)
Janus Moderate Allocation Fund | Class A, C, S, I, T Shares | Return Before Taxes | Class A
 
Average Annual Total Returnsrr_AverageAnnualReturnAbstract 
Columnrr_AverageAnnualReturnColumnNameClass A Shares
Labelrr_AverageAnnualReturnLabelReturn Before Taxes[3]
1 Yearrr_AverageAnnualReturnYear015.55%
5 Yearsrr_AverageAnnualReturnYear055.63%
Since Inceptionrr_AverageAnnualReturnSinceInception5.63%
Inception Daterr_AverageAnnualReturnInceptionDateDec. 30, 2005
Janus Moderate Allocation Fund | Class A, C, S, I, T Shares | Return Before Taxes | Class C
 
Average Annual Total Returnsrr_AverageAnnualReturnAbstract 
Columnrr_AverageAnnualReturnColumnNameClass C Shares
Labelrr_AverageAnnualReturnLabelReturn Before Taxes[4]
1 Yearrr_AverageAnnualReturnYear0110.23%
5 Yearsrr_AverageAnnualReturnYear056.11%
Since Inceptionrr_AverageAnnualReturnSinceInception6.10%
Inception Daterr_AverageAnnualReturnInceptionDateDec. 30, 2005
Janus Moderate Allocation Fund | Class A, C, S, I, T Shares | Return Before Taxes | Class S
 
Average Annual Total Returnsrr_AverageAnnualReturnAbstract 
Columnrr_AverageAnnualReturnColumnNameClass S Shares
Labelrr_AverageAnnualReturnLabelReturn Before Taxes
1 Yearrr_AverageAnnualReturnYear0111.93%
5 Yearsrr_AverageAnnualReturnYear056.62%
Since Inceptionrr_AverageAnnualReturnSinceInception6.62%
Inception Daterr_AverageAnnualReturnInceptionDateDec. 30, 2005
Janus Moderate Allocation Fund | Class A, C, S, I, T Shares | Return Before Taxes | Class I
 
Average Annual Total Returnsrr_AverageAnnualReturnAbstract 
Columnrr_AverageAnnualReturnColumnNameClass I Shares
Labelrr_AverageAnnualReturnLabelReturn Before Taxes
1 Yearrr_AverageAnnualReturnYear0112.42%
5 Yearsrr_AverageAnnualReturnYear057.07%
Since Inceptionrr_AverageAnnualReturnSinceInception7.07%
Inception Daterr_AverageAnnualReturnInceptionDateDec. 30, 2005
Janus Moderate Allocation Fund | Class A, C, S, I, T Shares | Return Before Taxes | Class T
 
Average Annual Total Returnsrr_AverageAnnualReturnAbstract 
Columnrr_AverageAnnualReturnColumnNameClass T Shares
Labelrr_AverageAnnualReturnLabelReturn Before Taxes
1 Yearrr_AverageAnnualReturnYear0112.19%
5 Yearsrr_AverageAnnualReturnYear057.07%
Since Inceptionrr_AverageAnnualReturnSinceInception7.07%
Inception Daterr_AverageAnnualReturnInceptionDateDec. 30, 2005
Janus Moderate Allocation Fund | Class A, C, S, I, T Shares | Return After Taxes on Distributions | Class T
 
Average Annual Total Returnsrr_AverageAnnualReturnAbstract 
Columnrr_AverageAnnualReturnColumnNameClass T Shares
Labelrr_AverageAnnualReturnLabelReturn After Taxes on Distributions
1 Yearrr_AverageAnnualReturnYear0111.36%
5 Yearsrr_AverageAnnualReturnYear056.21%
Since Inceptionrr_AverageAnnualReturnSinceInception6.20%
Inception Daterr_AverageAnnualReturnInceptionDateDec. 30, 2005
Janus Moderate Allocation Fund | Class A, C, S, I, T Shares | Return After Taxes on Distributions and Sale of Fund Shares | Class T
 
Average Annual Total Returnsrr_AverageAnnualReturnAbstract 
Columnrr_AverageAnnualReturnColumnNameClass T Shares
Labelrr_AverageAnnualReturnLabelReturn After Taxes on Distributions and Sale of Fund Shares[5]
1 Yearrr_AverageAnnualReturnYear018.03%
5 Yearsrr_AverageAnnualReturnYear055.65%
Since Inceptionrr_AverageAnnualReturnSinceInception5.65%
Inception Daterr_AverageAnnualReturnInceptionDateDec. 30, 2005
Janus Moderate Allocation Fund | Class A, C, S, I, T Shares | S&P 500® Index
 
Average Annual Total Returnsrr_AverageAnnualReturnAbstract 
Labelrr_AverageAnnualReturnLabelS&P 500® Index
Index No Deduction for Fees, Expenses, Taxes [Text]rr_IndexNoDeductionForFeesExpensesTaxes(reflects no deduction for expenses, fees, or taxes)
1 Yearrr_AverageAnnualReturnYear0115.06%
5 Yearsrr_AverageAnnualReturnYear052.29%
Since Inceptionrr_AverageAnnualReturnSinceInception2.29%
Inception Daterr_AverageAnnualReturnInceptionDateDec. 30, 2005
Janus Moderate Allocation Fund | Class A, C, S, I, T Shares | Moderate Allocation Index
 
Average Annual Total Returnsrr_AverageAnnualReturnAbstract 
Labelrr_AverageAnnualReturnLabelModerate Allocation Index
Index No Deduction for Fees, Expenses, Taxes [Text]rr_IndexNoDeductionForFeesExpensesTaxes(reflects no deduction for expenses, fees, or taxes)
1 Yearrr_AverageAnnualReturnYear0112.07%
5 Yearsrr_AverageAnnualReturnYear054.82%
Since Inceptionrr_AverageAnnualReturnSinceInception4.82%
Inception Daterr_AverageAnnualReturnInceptionDateDec. 30, 2005
Janus Moderate Allocation Fund | Class D Shares
 
Risk/Return:rr_RiskReturnAbstract 
Risk/Return [Heading]rr_RiskReturnHeadingFUND SUMMARY Janus Moderate Allocation Fund
Objective [Heading]rr_ObjectiveHeadingINVESTMENT OBJECTIVE
Objective, Primary [Text Block]rr_ObjectivePrimaryTextBlockJanus Moderate Allocation Fund seeks total return through growth of capital and income.[1]
FEES AND EXPENSES OF THE FUNDjif277751_FundFeesAndExpensesAbstract 
Expense [Heading]rr_ExpenseHeadingFEES AND EXPENSES OF THE FUND
Expense Narrative [Text Block]rr_ExpenseNarrativeTextBlockThis table describes the fees and expenses that you may pay if you buy and hold Shares of the Fund.
ANNUAL FUND OPERATING EXPENSESrr_OperatingExpensesAbstract 
Operating Expenses Caption [Text]rr_OperatingExpensesCaptionANNUAL 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 Terminationrr_FeeWaiverOrReimbursementOverAssetsDateOfTerminationNovember 1, 2012
EXAMPLE:rr_ExpenseExampleAbstract 
Expense Example [Heading]rr_ExpenseExampleHeadingEXAMPLE:
Expense Example Narrative [Text Block]rr_ExpenseExampleNarrativeTextBlockThe 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 [Heading]rr_ExpenseExampleByYearHeadingThe 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) without waivers remain the same. Although your actual costs may be higher or lower, based on these assumptions your costs would be:
Portfolio Turnover:jif277751_PortfolioTurnoverAltAbstract 
Portfolio Turnover [Heading]rr_PortfolioTurnoverHeadingPortfolio Turnover:
Portfolio Turnover [Text Block]rr_PortfolioTurnoverTextBlockThe 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 period, the Fund’s portfolio turnover rate was 15% of the average value of its portfolio.
Portfolio Turnover, Raterr_PortfolioTurnoverRate15.00%
Principal Investment Strategiesjif277751_PrincipalInvestmentStrategiesAbstract 
Strategy [Heading]rr_StrategyHeadingPRINCIPAL 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. 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 60% to stocks and 40% to bonds and money market securities. 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 among stocks, bonds, and cash equivalents. The portfolio manager 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. The portfolio manager continually monitors asset class allocations and periodically rebalances the Fund’s investments in the underlying funds. 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 60% of its investments to underlying funds that provide varying exposure to large U.S.-based companies, small- to mid-capitalization companies, and international companies (including those with exposure to emerging markets); and approximately 40% of its investments to underlying bond funds and money market instruments. 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 Risksjif277751_PrincipalInvestmentRisksAbstract 
Risk [Heading]rr_RiskHeadingPRINCIPAL 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 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 Janus Capital’s allocation of assets among the underlying funds and other securities, using the optimization process 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 concentrates.

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 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 60% 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 40% 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 their value 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.

Foreign Exposure Risk. Certain underlying funds may have significant exposure to foreign markets, including 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 are exposed to 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 specialized risks.

Mortgage-Backed Securities Risk. Mortgage-backed securities tend to be more sensitive to changes in interest rates than other types of 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.

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 common stocks, 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. 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.

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 can be substantially greater than the derivative’s original cost, and can therefore involve 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. Certain underlying funds may seek to earn additional income through lending their 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 underlying fund may experience delays and costs in recovering the security or gaining access to the collateral provided to collateralize the loan. If the underlying fund is unable to recover a security on loan, the underlying 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 underlying 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_RiskLoseMoneyThe biggest risk is that the Fund’s returns will vary, and you could lose money.
Risk Not Insured Depository Institution [Text]rr_RiskNotInsuredDepositoryInstitutionAn 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 INFORMATIONjif277751_FundPastPerformanceAbstract 
Bar Chart and Performance Table [Heading]rr_BarChartAndPerformanceTableHeadingPERFORMANCE 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_PerformanceAdditionalMarketIndexThe 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 Past Does Not Indicate Future [Text]rr_PerformancePastDoesNotIndicateFutureThe Fund’s past performance (before and after taxes) does not necessarily indicate how it will perform in the future.
Performance Table Closing [Text Block]rr_PerformanceTableClosingTextBlockUpdated performance information is available at janus.com/allfunds or by calling 1-800-525-3713.
Performance Availability Website Address [Text]rr_PerformanceAvailabilityWebSiteAddressjanus.com/allfunds
Performance Availability Phone [Text]rr_PerformanceAvailabilityPhone1-800-525-3713
Annual Total Returnsrr_BarChartTableAbstract 
Bar Chart [Heading]rr_BarChartHeadingAnnual 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, Labelrr_YearToDateReturnLabelThe Fund’s year-to-date return as of the calendar quarter ended September 30, 2011 was -7.45%.
Bar Chart, Year to Date Return, Daterr_BarChartYearToDateReturnDateSep. 30, 2011
Bar Chart, Year to Date Returnrr_BarChartYearToDateReturn(7.45%)
Average Annual Total Returnsrr_AverageAnnualReturnAbstract 
Captionrr_AverageAnnualReturnCaptionAverage Annual Total Returns (periods ended 12/31/10)
Performance Table Narrativerr_PerformanceTableNarrativeTextBlock

The Moderate Allocation Index is an internally-calculated, hypothetical combination of unmanaged indices that combines total returns from the Dow Jones Wilshire 5000 Index (40%), the Barclays Capital U.S. Aggregate Bond Index (40%), the MSCI EAFE® Index (18%), and the Morgan Stanley Capital International Emerging Markets Free IndexSM (2%).

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 Uses Highest Federal Raterr_PerformanceTableUsesHighestFederalRateAfter-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 Deferredrr_PerformanceTableNotRelevantToTaxDeferredActual 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.
Janus Moderate Allocation Fund | Class D Shares | Class D
 
ANNUAL FUND OPERATING EXPENSESrr_OperatingExpensesAbstract 
Operating Expenses Column [Text]rr_OperatingExpensesColumnNameClass D
Management Feesrr_ManagementFeesOverAssets0.05%
Other Expensesrr_OtherExpensesOverAssets0.20%
Acquired Fund Fees and Expensesrr_AcquiredFundFeesAndExpensesOverAssets0.63%
Total Annual Fund Operating Expensesrr_ExpensesOverAssets0.88%[8]
EXAMPLE:rr_ExpenseExampleAbstract 
Expense Example, By Year, Column [Text]rr_ExpenseExampleByYearColumnNameClass D Shares
1 Yearrr_ExpenseExampleYear0190
3 Yearsrr_ExpenseExampleYear03281
5 Yearsrr_ExpenseExampleYear05488
10 Yearsrr_ExpenseExampleYear101,084
Annual Total Returnsrr_BarChartTableAbstract 
2006rr_AnnualReturn200614.28%
2007rr_AnnualReturn200712.71%
2008rr_AnnualReturn2008(25.28%)
2009rr_AnnualReturn200930.34%
2010rr_AnnualReturn201012.31%
Highest Quarterly Return, Labelrr_HighestQuarterlyReturnLabelBest Quarter:
Highest Quarterly Return, Daterr_BarChartHighestQuarterlyReturnDateJun. 30, 2009
Highest Quarterly Returnrr_BarChartHighestQuarterlyReturn14.27%
Lowest Quarterly Return, Labelrr_LowestQuarterlyReturnLabelWorst Quarter:
Lowest Quarterly Return, Daterr_BarChartLowestQuarterlyReturnDateDec. 31, 2008
Lowest Quarterly Returnrr_BarChartLowestQuarterlyReturn(11.62%)
Janus Moderate Allocation Fund | Class D Shares | Return Before Taxes | Class D
 
Average Annual Total Returnsrr_AverageAnnualReturnAbstract 
Columnrr_AverageAnnualReturnColumnNameClass D Shares
Labelrr_AverageAnnualReturnLabelReturn Before Taxes
1 Yearrr_AverageAnnualReturnYear0112.31%
5 Yearsrr_AverageAnnualReturnYear057.09%
Since Inceptionrr_AverageAnnualReturnSinceInception7.09%
Inception Daterr_AverageAnnualReturnInceptionDateDec. 30, 2005
Janus Moderate Allocation Fund | Class D Shares | Return After Taxes on Distributions | Class D
 
Average Annual Total Returnsrr_AverageAnnualReturnAbstract 
Columnrr_AverageAnnualReturnColumnNameClass D Shares
Labelrr_AverageAnnualReturnLabelReturn After Taxes on Distributions
1 Yearrr_AverageAnnualReturnYear0111.47%
5 Yearsrr_AverageAnnualReturnYear056.23%
Since Inceptionrr_AverageAnnualReturnSinceInception6.22%
Inception Daterr_AverageAnnualReturnInceptionDateDec. 30, 2005
Janus Moderate Allocation Fund | Class D Shares | Return After Taxes on Distributions and Sale of Fund Shares | Class D
 
Average Annual Total Returnsrr_AverageAnnualReturnAbstract 
Columnrr_AverageAnnualReturnColumnNameClass D Shares
Labelrr_AverageAnnualReturnLabelReturn After Taxes on Distributions and Sale of Fund Shares[5]
1 Yearrr_AverageAnnualReturnYear018.11%
5 Yearsrr_AverageAnnualReturnYear055.67%
Since Inceptionrr_AverageAnnualReturnSinceInception5.67%
Inception Daterr_AverageAnnualReturnInceptionDateDec. 30, 2005
Janus Moderate Allocation Fund | Class D Shares | S&P 500® Index
 
Average Annual Total Returnsrr_AverageAnnualReturnAbstract 
Labelrr_AverageAnnualReturnLabelS&P 500® Index
Index No Deduction for Fees, Expenses, Taxes [Text]rr_IndexNoDeductionForFeesExpensesTaxes(reflects no deduction for expenses, fees, or taxes)
1 Yearrr_AverageAnnualReturnYear0115.06%
5 Yearsrr_AverageAnnualReturnYear052.29%
Since Inceptionrr_AverageAnnualReturnSinceInception2.29%
Inception Daterr_AverageAnnualReturnInceptionDateDec. 30, 2005
Janus Moderate Allocation Fund | Class D Shares | Moderate Allocation Index
 
Average Annual Total Returnsrr_AverageAnnualReturnAbstract 
Labelrr_AverageAnnualReturnLabelModerate Allocation Index
Index No Deduction for Fees, Expenses, Taxes [Text]rr_IndexNoDeductionForFeesExpensesTaxes(reflects no deduction for expenses, fees, or taxes)
1 Yearrr_AverageAnnualReturnYear0112.07%
5 Yearsrr_AverageAnnualReturnYear054.82%
Since Inceptionrr_AverageAnnualReturnSinceInception4.82%
Inception Daterr_AverageAnnualReturnInceptionDateDec. 30, 2005
Janus Growth Allocation Fund | Class A, C, S, I, T Shares
 
Risk/Return:rr_RiskReturnAbstract 
Risk/Return [Heading]rr_RiskReturnHeadingFUND SUMMARY Janus Growth Allocation Fund
Objective [Heading]rr_ObjectiveHeadingINVESTMENT OBJECTIVE
Objective, Primary [Text Block]rr_ObjectivePrimaryTextBlockJanus Growth Allocation Fund seeks total return through a primary emphasis on growth of capital with a secondary emphasis on income.[1]
FEES AND EXPENSES OF THE FUNDjif277751_FundFeesAndExpensesAbstract 
Expense [Heading]rr_ExpenseHeadingFEES AND EXPENSES OF THE FUND
Expense Narrative [Text Block]rr_ExpenseNarrativeTextBlockThis 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.
Expense Breakpoint Discountsjif277751_ExpenseBreakpointDiscountsAbstract 
Expense Breakpoint Discounts [Text]rr_ExpenseBreakpointDiscountsFor 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 44 of the Fund’s Prospectus and in the “Purchases” section on page 64 of the Fund’s Statement of Additional Information.
Expense Breakpoint, Minimum Investment Required [Amount]rr_ExpenseBreakpointMinimumInvestmentRequiredAmount50,000
SHAREHOLDER FEESrr_ShareholderFeesAbstract 
Shareholder Fees Caption [Text]rr_ShareholderFeesCaptionSHAREHOLDER FEES (fees paid directly from your investment)
ANNUAL FUND OPERATING EXPENSESrr_OperatingExpensesAbstract 
Operating Expenses Caption [Text]rr_OperatingExpensesCaptionANNUAL 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 Terminationrr_FeeWaiverOrReimbursementOverAssetsDateOfTerminationNovember 1, 2012
EXAMPLE:rr_ExpenseExampleAbstract 
Expense Example [Heading]rr_ExpenseExampleHeadingEXAMPLE:
Expense Example Narrative [Text Block]rr_ExpenseExampleNarrativeTextBlockThe 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 [Heading]rr_ExpenseExampleByYearHeadingThe 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) without waivers remain the same. Although your actual costs may be higher or lower, based on these assumptions your costs would be:
Expense Example by, Year, Caption [Text]rr_ExpenseExampleByYearCaptionIf Shares are redeemed:
Expense Example, No Redemption:rr_ExpenseExampleNoRedemptionAbstract 
Expense Example, No Redemption, By Year, Caption [Text]rr_ExpenseExampleNoRedemptionByYearCaptionIf Shares are not redeemed:
Portfolio Turnover:jif277751_PortfolioTurnoverAltAbstract 
Portfolio Turnover [Heading]rr_PortfolioTurnoverHeadingPortfolio Turnover:
Portfolio Turnover [Text Block]rr_PortfolioTurnoverTextBlockThe 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 period, the Fund’s portfolio turnover rate was 26% of the average value of its portfolio.
Portfolio Turnover, Raterr_PortfolioTurnoverRate26.00%
Principal Investment Strategiesjif277751_PrincipalInvestmentStrategiesAbstract 
Strategy [Heading]rr_StrategyHeadingPRINCIPAL 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. 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 80% to stocks and 20% to bonds and money market securities. 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 among stocks, bonds, and cash equivalents. The portfolio manager 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. The portfolio manager continually monitors asset class allocations and periodically rebalances the Fund’s investments in the underlying funds. 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 80% of its investments to underlying funds that provide varying exposure to large U.S.-based companies, small- to mid-capitalization companies, and international companies (including those with exposure to emerging markets); and approximately 20% of its investments to underlying bond funds and money market instruments. 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 Risksjif277751_PrincipalInvestmentRisksAbstract 
Risk [Heading]rr_RiskHeadingPRINCIPAL 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 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 Janus Capital’s allocation of assets among the underlying funds and other securities, using the optimization process 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 concentrates.

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 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 80% 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 20% 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 their value 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.

Foreign Exposure Risk. Certain underlying funds may have significant exposure to foreign markets, including 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 are exposed to 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 specialized risks.

Mortgage-Backed Securities Risk. Mortgage-backed securities tend to be more sensitive to changes in interest rates than other types of 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.

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 common stocks, 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. 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.

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 can be substantially greater than the derivative’s original cost, and can therefore involve 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. Certain underlying funds may seek to earn additional income through lending their 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 underlying fund may experience delays and costs in recovering the security or gaining access to the collateral provided to collateralize the loan. If the underlying fund is unable to recover a security on loan, the underlying 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 underlying 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_RiskLoseMoneyThe biggest risk is that the Fund’s returns will vary, and you could lose money.
Risk Not Insured Depository Institution [Text]rr_RiskNotInsuredDepositoryInstitutionAn 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 INFORMATIONjif277751_FundPastPerformanceAbstract 
Bar Chart and Performance Table [Heading]rr_BarChartAndPerformanceTableHeadingPERFORMANCE 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, 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.

Bar Chart Does Not Reflect Sales Loads [Text]rr_BarChartDoesNotReflectSalesLoadsThe 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.
Performance Additional Market Index [Text]rr_PerformanceAdditionalMarketIndexThe 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 Past Does Not Indicate Future [Text]rr_PerformancePastDoesNotIndicateFutureThe Fund’s past performance (before and after taxes) does not necessarily indicate how it will perform in the future.
Performance Table Closing [Text Block]rr_PerformanceTableClosingTextBlockUpdated performance information is available at janus.com/advisor/mutual-funds or by calling 1-877-335-2687.
Performance Availability Website Address [Text]rr_PerformanceAvailabilityWebSiteAddressjanus.com/advisor/mutual-funds
Performance Availability Phone [Text]rr_PerformanceAvailabilityPhone1-877-335-2687
Annual Total Returnsrr_BarChartTableAbstract 
Bar Chart [Heading]rr_BarChartHeadingAnnual Total Returns for Class T 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, Labelrr_YearToDateReturnLabelThe Fund’s year-to-date return as of the calendar quarter ended September 30, 2011 was -12.07%.
Bar Chart, Year to Date Return, Daterr_BarChartYearToDateReturnDateSep. 30, 2011
Bar Chart, Year to Date Returnrr_BarChartYearToDateReturn(12.07%)
Average Annual Total Returnsrr_AverageAnnualReturnAbstract 
Captionrr_AverageAnnualReturnCaptionAverage Annual Total Returns (periods ended 12/31/10)
Performance Table Narrativerr_PerformanceTableNarrativeTextBlock

The Growth Allocation Index is 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 Capital U.S. Aggregate Bond Index (20%), and the Morgan Stanley Capital International Emerging Markets Free IndexSM (5%).

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 Uses Highest Federal Raterr_PerformanceTableUsesHighestFederalRateAfter-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 Deferredrr_PerformanceTableNotRelevantToTaxDeferredActual 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_PerformanceTableOneClassOfAfterTaxShownAfter-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.
Janus Growth Allocation Fund | Class A, C, S, I, T Shares | Class A
 
SHAREHOLDER FEESrr_ShareholderFeesAbstract 
Shareholder Fees Column [Text]rr_ShareholderFeesColumnNameClass A
Maximum Sales Charge (load) Imposed on Purchases (as a percentage of offering price)rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice5.75%
Maximum Deferred Sales Charge (load) (as a percentage of the lower of original purchase price or redemption proceeds)rr_MaximumDeferredSalesChargeOverOther none
ANNUAL FUND OPERATING EXPENSESrr_OperatingExpensesAbstract 
Operating Expenses Column [Text]rr_OperatingExpensesColumnNameClass A
Management Feesrr_ManagementFeesOverAssets0.05%
Distribution/Service (12b-1) Feesrr_DistributionAndService12b1FeesOverAssets0.25%
Other Expensesrr_OtherExpensesOverAssets0.14%
Acquired Fund Fees and Expensesrr_AcquiredFundFeesAndExpensesOverAssets0.68%
Total Annual Fund Operating Expensesrr_ExpensesOverAssets1.12%[9]
EXAMPLE:rr_ExpenseExampleAbstract 
Expense Example, By Year, Column [Text]rr_ExpenseExampleByYearColumnNameClass A Shares
1 Yearrr_ExpenseExampleYear01683
3 Yearsrr_ExpenseExampleYear03911
5 Yearsrr_ExpenseExampleYear051,156
10 Yearsrr_ExpenseExampleYear101,860
Expense Example, No Redemption:rr_ExpenseExampleNoRedemptionAbstract 
Expense Example, No Redemption, By Year, Column [Text]rr_ExpenseExampleNoRedemptionByYearColumnNameClass A Shares
1 Yearrr_ExpenseExampleNoRedemptionYear01683
3 Yearsrr_ExpenseExampleNoRedemptionYear03911
5 Yearsrr_ExpenseExampleNoRedemptionYear051,156
10 Yearsrr_ExpenseExampleNoRedemptionYear101,860
Janus Growth Allocation Fund | Class A, C, S, I, T Shares | Class C
 
SHAREHOLDER FEESrr_ShareholderFeesAbstract 
Shareholder Fees Column [Text]rr_ShareholderFeesColumnNameClass 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_MaximumDeferredSalesChargeOverOther1.00%
ANNUAL FUND OPERATING EXPENSESrr_OperatingExpensesAbstract 
Operating Expenses Column [Text]rr_OperatingExpensesColumnNameClass C
Management Feesrr_ManagementFeesOverAssets0.05%
Distribution/Service (12b-1) Feesrr_DistributionAndService12b1FeesOverAssets1.00%
Other Expensesrr_OtherExpensesOverAssets0.16%
Acquired Fund Fees and Expensesrr_AcquiredFundFeesAndExpensesOverAssets0.68%
Total Annual Fund Operating Expensesrr_ExpensesOverAssets1.89%[9]
EXAMPLE:rr_ExpenseExampleAbstract 
Expense Example, By Year, Column [Text]rr_ExpenseExampleByYearColumnNameClass C Shares
1 Yearrr_ExpenseExampleYear01292
3 Yearsrr_ExpenseExampleYear03594
5 Yearsrr_ExpenseExampleYear051,021
10 Yearsrr_ExpenseExampleYear102,212
Expense Example, No Redemption:rr_ExpenseExampleNoRedemptionAbstract 
Expense Example, No Redemption, By Year, Column [Text]rr_ExpenseExampleNoRedemptionByYearColumnNameClass C Shares
1 Yearrr_ExpenseExampleNoRedemptionYear01192
3 Yearsrr_ExpenseExampleNoRedemptionYear03594
5 Yearsrr_ExpenseExampleNoRedemptionYear051,021
10 Yearsrr_ExpenseExampleNoRedemptionYear102,212
Janus Growth Allocation Fund | Class A, C, S, I, T Shares | Class S
 
SHAREHOLDER FEESrr_ShareholderFeesAbstract 
Shareholder Fees Column [Text]rr_ShareholderFeesColumnNameClass 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
ANNUAL FUND OPERATING EXPENSESrr_OperatingExpensesAbstract 
Operating Expenses Column [Text]rr_OperatingExpensesColumnNameClass S
Management Feesrr_ManagementFeesOverAssets0.05%
Distribution/Service (12b-1) Feesrr_DistributionAndService12b1FeesOverAssets0.25%
Other Expensesrr_OtherExpensesOverAssets0.37%
Acquired Fund Fees and Expensesrr_AcquiredFundFeesAndExpensesOverAssets0.68%
Total Annual Fund Operating Expensesrr_ExpensesOverAssets1.35%[9]
EXAMPLE:rr_ExpenseExampleAbstract 
Expense Example, By Year, Column [Text]rr_ExpenseExampleByYearColumnNameClass S Shares
1 Yearrr_ExpenseExampleYear01137
3 Yearsrr_ExpenseExampleYear03428
5 Yearsrr_ExpenseExampleYear05739
10 Yearsrr_ExpenseExampleYear101,624
Expense Example, No Redemption:rr_ExpenseExampleNoRedemptionAbstract 
Expense Example, No Redemption, By Year, Column [Text]rr_ExpenseExampleNoRedemptionByYearColumnNameClass S Shares
1 Yearrr_ExpenseExampleNoRedemptionYear01137
3 Yearsrr_ExpenseExampleNoRedemptionYear03428
5 Yearsrr_ExpenseExampleNoRedemptionYear05739
10 Yearsrr_ExpenseExampleNoRedemptionYear101,624
Janus Growth Allocation Fund | Class A, C, S, I, T Shares | Class I
 
SHAREHOLDER FEESrr_ShareholderFeesAbstract 
Shareholder Fees Column [Text]rr_ShareholderFeesColumnNameClass 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
ANNUAL FUND OPERATING EXPENSESrr_OperatingExpensesAbstract 
Operating Expenses Column [Text]rr_OperatingExpensesColumnNameClass I
Management Feesrr_ManagementFeesOverAssets0.05%
Distribution/Service (12b-1) Feesrr_DistributionAndService12b1FeesOverAssets none
Other Expensesrr_OtherExpensesOverAssets0.20%
Acquired Fund Fees and Expensesrr_AcquiredFundFeesAndExpensesOverAssets0.68%
Total Annual Fund Operating Expensesrr_ExpensesOverAssets0.93%[9]
EXAMPLE:rr_ExpenseExampleAbstract 
Expense Example, By Year, Column [Text]rr_ExpenseExampleByYearColumnNameClass I Shares
1 Yearrr_ExpenseExampleYear0195
3 Yearsrr_ExpenseExampleYear03296
5 Yearsrr_ExpenseExampleYear05515
10 Yearsrr_ExpenseExampleYear101,143
Expense Example, No Redemption:rr_ExpenseExampleNoRedemptionAbstract 
Expense Example, No Redemption, By Year, Column [Text]rr_ExpenseExampleNoRedemptionByYearColumnNameClass I Shares
1 Yearrr_ExpenseExampleNoRedemptionYear0195
3 Yearsrr_ExpenseExampleNoRedemptionYear03296
5 Yearsrr_ExpenseExampleNoRedemptionYear05515
10 Yearsrr_ExpenseExampleNoRedemptionYear101,143
Janus Growth Allocation Fund | Class A, C, S, I, T Shares | Class T
 
SHAREHOLDER FEESrr_ShareholderFeesAbstract 
Shareholder Fees Column [Text]rr_ShareholderFeesColumnNameClass 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
ANNUAL FUND OPERATING EXPENSESrr_OperatingExpensesAbstract 
Operating Expenses Column [Text]rr_OperatingExpensesColumnNameClass T
Management Feesrr_ManagementFeesOverAssets0.05%
Distribution/Service (12b-1) Feesrr_DistributionAndService12b1FeesOverAssets none
Other Expensesrr_OtherExpensesOverAssets0.30%
Acquired Fund Fees and Expensesrr_AcquiredFundFeesAndExpensesOverAssets0.68%
Total Annual Fund Operating Expensesrr_ExpensesOverAssets1.03%[9]
EXAMPLE:rr_ExpenseExampleAbstract 
Expense Example, By Year, Column [Text]rr_ExpenseExampleByYearColumnNameClass T Shares
1 Yearrr_ExpenseExampleYear01105
3 Yearsrr_ExpenseExampleYear03328
5 Yearsrr_ExpenseExampleYear05569
10 Yearsrr_ExpenseExampleYear101,259
Expense Example, No Redemption:rr_ExpenseExampleNoRedemptionAbstract 
Expense Example, No Redemption, By Year, Column [Text]rr_ExpenseExampleNoRedemptionByYearColumnNameClass T Shares
1 Yearrr_ExpenseExampleNoRedemptionYear01105
3 Yearsrr_ExpenseExampleNoRedemptionYear03328
5 Yearsrr_ExpenseExampleNoRedemptionYear05569
10 Yearsrr_ExpenseExampleNoRedemptionYear101,259
Annual Total Returnsrr_BarChartTableAbstract 
2006rr_AnnualReturn200618.51%
2007rr_AnnualReturn200715.73%
2008rr_AnnualReturn2008(34.91%)
2009rr_AnnualReturn200935.79%
2010rr_AnnualReturn201013.40%
Highest Quarterly Return, Labelrr_HighestQuarterlyReturnLabelBest Quarter:
Highest Quarterly Return, Daterr_BarChartHighestQuarterlyReturnDateJun. 30, 2009
Highest Quarterly Returnrr_BarChartHighestQuarterlyReturn18.37%
Lowest Quarterly Return, Labelrr_LowestQuarterlyReturnLabelWorst Quarter:
Lowest Quarterly Return, Daterr_BarChartLowestQuarterlyReturnDateDec. 31, 2008
Lowest Quarterly Returnrr_BarChartLowestQuarterlyReturn(18.05%)
Janus Growth Allocation Fund | Class A, C, S, I, T Shares | Return Before Taxes | Class A
 
Average Annual Total Returnsrr_AverageAnnualReturnAbstract 
Columnrr_AverageAnnualReturnColumnNameClass A Shares
Labelrr_AverageAnnualReturnLabelReturn Before Taxes[3]
1 Yearrr_AverageAnnualReturnYear016.86%
5 Yearsrr_AverageAnnualReturnYear055.15%
Since Inceptionrr_AverageAnnualReturnSinceInception5.15%
Inception Daterr_AverageAnnualReturnInceptionDateDec. 30, 2005
Janus Growth Allocation Fund | Class A, C, S, I, T Shares | Return Before Taxes | Class C
 
Average Annual Total Returnsrr_AverageAnnualReturnAbstract 
Columnrr_AverageAnnualReturnColumnNameClass C Shares
Labelrr_AverageAnnualReturnLabelReturn Before Taxes[4]
1 Yearrr_AverageAnnualReturnYear0111.39%
5 Yearsrr_AverageAnnualReturnYear055.62%
Since Inceptionrr_AverageAnnualReturnSinceInception5.62%
Inception Daterr_AverageAnnualReturnInceptionDateDec. 30, 2005
Janus Growth Allocation Fund | Class A, C, S, I, T Shares | Return Before Taxes | Class S
 
Average Annual Total Returnsrr_AverageAnnualReturnAbstract 
Columnrr_AverageAnnualReturnColumnNameClass S Shares
Labelrr_AverageAnnualReturnLabelReturn Before Taxes
1 Yearrr_AverageAnnualReturnYear0113.19%
5 Yearsrr_AverageAnnualReturnYear056.16%
Since Inceptionrr_AverageAnnualReturnSinceInception6.16%
Inception Daterr_AverageAnnualReturnInceptionDateDec. 30, 2005
Janus Growth Allocation Fund | Class A, C, S, I, T Shares | Return Before Taxes | Class I
 
Average Annual Total Returnsrr_AverageAnnualReturnAbstract 
Columnrr_AverageAnnualReturnColumnNameClass I Shares
Labelrr_AverageAnnualReturnLabelReturn Before Taxes
1 Yearrr_AverageAnnualReturnYear0113.65%
5 Yearsrr_AverageAnnualReturnYear056.57%
Since Inceptionrr_AverageAnnualReturnSinceInception6.57%
Inception Daterr_AverageAnnualReturnInceptionDateDec. 30, 2005
Janus Growth Allocation Fund | Class A, C, S, I, T Shares | Return Before Taxes | Class T
 
Average Annual Total Returnsrr_AverageAnnualReturnAbstract 
Columnrr_AverageAnnualReturnColumnNameClass T Shares
Labelrr_AverageAnnualReturnLabelReturn Before Taxes
1 Yearrr_AverageAnnualReturnYear0113.40%
5 Yearsrr_AverageAnnualReturnYear056.57%
Since Inceptionrr_AverageAnnualReturnSinceInception6.57%
Inception Daterr_AverageAnnualReturnInceptionDateDec. 30, 2005
Janus Growth Allocation Fund | Class A, C, S, I, T Shares | Return After Taxes on Distributions | Class T
 
Average Annual Total Returnsrr_AverageAnnualReturnAbstract 
Columnrr_AverageAnnualReturnColumnNameClass T Shares
Labelrr_AverageAnnualReturnLabelReturn After Taxes on Distributions
1 Yearrr_AverageAnnualReturnYear0112.92%
5 Yearsrr_AverageAnnualReturnYear055.92%
Since Inceptionrr_AverageAnnualReturnSinceInception5.92%
Inception Daterr_AverageAnnualReturnInceptionDateDec. 30, 2005
Janus Growth Allocation Fund | Class A, C, S, I, T Shares | Return After Taxes on Distributions and Sale of Fund Shares | Class T
 
Average Annual Total Returnsrr_AverageAnnualReturnAbstract 
Columnrr_AverageAnnualReturnColumnNameClass T Shares
Labelrr_AverageAnnualReturnLabelReturn After Taxes on Distributions and Sale of Fund Shares[5]
1 Yearrr_AverageAnnualReturnYear018.85%
5 Yearsrr_AverageAnnualReturnYear055.38%
Since Inceptionrr_AverageAnnualReturnSinceInception5.37%
Inception Daterr_AverageAnnualReturnInceptionDateDec. 30, 2005
Janus Growth Allocation Fund | Class A, C, S, I, T Shares | S&P 500® Index
 
Average Annual Total Returnsrr_AverageAnnualReturnAbstract 
Labelrr_AverageAnnualReturnLabelS&P 500® Index
Index No Deduction for Fees, Expenses, Taxes [Text]rr_IndexNoDeductionForFeesExpensesTaxes(reflects no deduction for expenses, fees, or taxes)
1 Yearrr_AverageAnnualReturnYear0115.06%
5 Yearsrr_AverageAnnualReturnYear052.29%
Since Inceptionrr_AverageAnnualReturnSinceInception2.29%
Inception Daterr_AverageAnnualReturnInceptionDateDec. 30, 2005
Janus Growth Allocation Fund | Class A, C, S, I, T Shares | Growth Allocation Index
 
Average Annual Total Returnsrr_AverageAnnualReturnAbstract 
Labelrr_AverageAnnualReturnLabelGrowth Allocation Index
Index No Deduction for Fees, Expenses, Taxes [Text]rr_IndexNoDeductionForFeesExpensesTaxes(reflects no deduction for expenses, fees, or taxes)
1 Yearrr_AverageAnnualReturnYear0113.51%
5 Yearsrr_AverageAnnualReturnYear054.43%
Since Inceptionrr_AverageAnnualReturnSinceInception4.43%
Inception Daterr_AverageAnnualReturnInceptionDateDec. 30, 2005
Janus Growth Allocation Fund | Class D Shares
 
Risk/Return:rr_RiskReturnAbstract 
Risk/Return [Heading]rr_RiskReturnHeadingFUND SUMMARY Janus Growth Allocation Fund
Objective [Heading]rr_ObjectiveHeadingINVESTMENT OBJECTIVE
Objective, Primary [Text Block]rr_ObjectivePrimaryTextBlockJanus Growth Allocation Fund seeks total return through a primary emphasis on growth of capital with a secondary emphasis on income.[1]
FEES AND EXPENSES OF THE FUNDjif277751_FundFeesAndExpensesAbstract 
Expense [Heading]rr_ExpenseHeadingFEES AND EXPENSES OF THE FUND
Expense Narrative [Text Block]rr_ExpenseNarrativeTextBlockThis table describes the fees and expenses that you may pay if you buy and hold Shares of the Fund.
ANNUAL FUND OPERATING EXPENSESrr_OperatingExpensesAbstract 
Operating Expenses Caption [Text]rr_OperatingExpensesCaptionANNUAL 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 Terminationrr_FeeWaiverOrReimbursementOverAssetsDateOfTerminationNovember 1, 2012
EXAMPLE:rr_ExpenseExampleAbstract 
Expense Example [Heading]rr_ExpenseExampleHeadingEXAMPLE:
Expense Example Narrative [Text Block]rr_ExpenseExampleNarrativeTextBlockThe 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 [Heading]rr_ExpenseExampleByYearHeadingThe 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) without waivers remain the same. Although your actual costs may be higher or lower, based on these assumptions your costs would be:
Portfolio Turnover:jif277751_PortfolioTurnoverAltAbstract 
Portfolio Turnover [Heading]rr_PortfolioTurnoverHeadingPortfolio Turnover:
Portfolio Turnover [Text Block]rr_PortfolioTurnoverTextBlockThe 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 period, the Fund’s portfolio turnover rate was 26% of the average value of its portfolio.
Portfolio Turnover, Raterr_PortfolioTurnoverRate26.00%
Principal Investment Strategiesjif277751_PrincipalInvestmentStrategiesAbstract 
Strategy [Heading]rr_StrategyHeadingPRINCIPAL 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. 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 80% to stocks and 20% to bonds and money market securities. 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 among stocks, bonds, and cash equivalents. The portfolio manager 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. The portfolio manager continually monitors asset class allocations and periodically rebalances the Fund’s investments in the underlying funds. 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 80% of its investments to underlying funds that provide varying exposure to large U.S.-based companies, small- to mid-capitalization companies, and international companies (including those with exposure to emerging markets); and approximately 20% of its investments to underlying bond funds and money market instruments. 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 Risksjif277751_PrincipalInvestmentRisksAbstract 
Risk [Heading]rr_RiskHeadingPRINCIPAL 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 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 Janus Capital’s allocation of assets among the underlying funds and other securities, using the optimization process 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 concentrates.

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 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 80% 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 20% 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 their value 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.

Foreign Exposure Risk. Certain underlying funds may have significant exposure to foreign markets, including 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 are exposed to 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 specialized risks.

Mortgage-Backed Securities Risk. Mortgage-backed securities tend to be more sensitive to changes in interest rates than other types of 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.

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 common stocks, 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. 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.

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 can be substantially greater than the derivative’s original cost, and can therefore involve 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. Certain underlying funds may seek to earn additional income through lending their 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 underlying fund may experience delays and costs in recovering the security or gaining access to the collateral provided to collateralize the loan. If the underlying fund is unable to recover a security on loan, the underlying 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 underlying 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_RiskLoseMoneyThe biggest risk is that the Fund’s returns will vary, and you could lose money.
Risk Not Insured Depository Institution [Text]rr_RiskNotInsuredDepositoryInstitutionAn 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 INFORMATIONjif277751_FundPastPerformanceAbstract 
Bar Chart and Performance Table [Heading]rr_BarChartAndPerformanceTableHeadingPERFORMANCE 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_PerformanceAdditionalMarketIndexThe 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 Past Does Not Indicate Future [Text]rr_PerformancePastDoesNotIndicateFutureThe Fund’s past performance (before and after taxes) does not necessarily indicate how it will perform in the future.
Performance Table Closing [Text Block]rr_PerformanceTableClosingTextBlockUpdated performance information is available at janus.com/allfunds or by calling 1-800-525-3713.
Performance Availability Website Address [Text]rr_PerformanceAvailabilityWebSiteAddressjanus.com/allfunds
Performance Availability Phone [Text]rr_PerformanceAvailabilityPhone1-800-525-3713
Annual Total Returnsrr_BarChartTableAbstract 
Bar Chart [Heading]rr_BarChartHeadingAnnual 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, Labelrr_YearToDateReturnLabelThe Fund’s year-to-date return as of the calendar quarter ended September 30, 2011 was -11.99%.
Bar Chart, Year to Date Return, Daterr_BarChartYearToDateReturnDateSep. 30, 2011
Bar Chart, Year to Date Returnrr_BarChartYearToDateReturn(11.99%)
Average Annual Total Returnsrr_AverageAnnualReturnAbstract 
Captionrr_AverageAnnualReturnCaptionAverage Annual Total Returns (periods ended 12/31/10)
Performance Table Narrativerr_PerformanceTableNarrativeTextBlock

The Growth Allocation Index is 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 Capital U.S. Aggregate Bond Index (20%), and the Morgan Stanley Capital International Emerging Markets Free IndexSM (5%).

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 Uses Highest Federal Raterr_PerformanceTableUsesHighestFederalRateAfter-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 Deferredrr_PerformanceTableNotRelevantToTaxDeferredActual 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.
Janus Growth Allocation Fund | Class D Shares | Class D
 
ANNUAL FUND OPERATING EXPENSESrr_OperatingExpensesAbstract 
Operating Expenses Column [Text]rr_OperatingExpensesColumnNameClass D
Management Feesrr_ManagementFeesOverAssets0.05%
Other Expensesrr_OtherExpensesOverAssets0.23%
Acquired Fund Fees and Expensesrr_AcquiredFundFeesAndExpensesOverAssets0.68%
Total Annual Fund Operating Expensesrr_ExpensesOverAssets0.96%[10]
EXAMPLE:rr_ExpenseExampleAbstract 
Expense Example, By Year, Column [Text]rr_ExpenseExampleByYearColumnNameClass D Shares
1 Yearrr_ExpenseExampleYear0198
3 Yearsrr_ExpenseExampleYear03306
5 Yearsrr_ExpenseExampleYear05531
10 Yearsrr_ExpenseExampleYear101,178
Annual Total Returnsrr_BarChartTableAbstract 
2006rr_AnnualReturn200618.51%
2007rr_AnnualReturn200715.73%
2008rr_AnnualReturn2008(34.91%)
2009rr_AnnualReturn200935.79%
2010rr_AnnualReturn201013.53%
Highest Quarterly Return, Labelrr_HighestQuarterlyReturnLabelBest Quarter:
Highest Quarterly Return, Daterr_BarChartHighestQuarterlyReturnDateJun. 30, 2009
Highest Quarterly Returnrr_BarChartHighestQuarterlyReturn18.37%
Lowest Quarterly Return, Labelrr_LowestQuarterlyReturnLabelWorst Quarter:
Lowest Quarterly Return, Daterr_BarChartLowestQuarterlyReturnDateDec. 31, 2008
Lowest Quarterly Returnrr_BarChartLowestQuarterlyReturn(18.05%)
Janus Growth Allocation Fund | Class D Shares | Return Before Taxes | Class D
 
Average Annual Total Returnsrr_AverageAnnualReturnAbstract 
Columnrr_AverageAnnualReturnColumnNameClass D Shares
Labelrr_AverageAnnualReturnLabelReturn Before Taxes
1 Yearrr_AverageAnnualReturnYear0113.53%
5 Yearsrr_AverageAnnualReturnYear056.59%
Since Inceptionrr_AverageAnnualReturnSinceInception6.59%
Inception Daterr_AverageAnnualReturnInceptionDateDec. 30, 2005
Janus Growth Allocation Fund | Class D Shares | Return After Taxes on Distributions | Class D
 
Average Annual Total Returnsrr_AverageAnnualReturnAbstract 
Columnrr_AverageAnnualReturnColumnNameClass D Shares
Labelrr_AverageAnnualReturnLabelReturn After Taxes on Distributions
1 Yearrr_AverageAnnualReturnYear0113.01%
5 Yearsrr_AverageAnnualReturnYear055.94%
Since Inceptionrr_AverageAnnualReturnSinceInception5.93%
Inception Daterr_AverageAnnualReturnInceptionDateDec. 30, 2005
Janus Growth Allocation Fund | Class D Shares | Return After Taxes on Distributions and Sale of Fund Shares | Class D
 
Average Annual Total Returnsrr_AverageAnnualReturnAbstract 
Columnrr_AverageAnnualReturnColumnNameClass D Shares
Labelrr_AverageAnnualReturnLabelReturn After Taxes on Distributions and Sale of Fund Shares[5]
1 Yearrr_AverageAnnualReturnYear018.94%
5 Yearsrr_AverageAnnualReturnYear055.39%
Since Inceptionrr_AverageAnnualReturnSinceInception5.39%
Inception Daterr_AverageAnnualReturnInceptionDateDec. 30, 2005
Janus Growth Allocation Fund | Class D Shares | S&P 500® Index
 
Average Annual Total Returnsrr_AverageAnnualReturnAbstract 
Labelrr_AverageAnnualReturnLabelS&P 500® Index
Index No Deduction for Fees, Expenses, Taxes [Text]rr_IndexNoDeductionForFeesExpensesTaxes(reflects no deduction for expenses, fees, or taxes)
1 Yearrr_AverageAnnualReturnYear0115.06%
5 Yearsrr_AverageAnnualReturnYear052.29%
Since Inceptionrr_AverageAnnualReturnSinceInception2.29%
Inception Daterr_AverageAnnualReturnInceptionDateDec. 30, 2005
Janus Growth Allocation Fund | Class D Shares | Growth Allocation Index
 
Average Annual Total Returnsrr_AverageAnnualReturnAbstract 
Labelrr_AverageAnnualReturnLabelGrowth Allocation Index
Index No Deduction for Fees, Expenses, Taxes [Text]rr_IndexNoDeductionForFeesExpensesTaxes(reflects no deduction for expenses, fees, or taxes)
1 Yearrr_AverageAnnualReturnYear0113.51%
5 Yearsrr_AverageAnnualReturnYear054.43%
Since Inceptionrr_AverageAnnualReturnSinceInception4.43%
Inception Daterr_AverageAnnualReturnInceptionDateDec. 30, 2005
Janus World Allocation Fund | Class A, C, S, I, T Shares
 
Risk/Return:rr_RiskReturnAbstract 
Risk/Return [Heading]rr_RiskReturnHeadingFUND SUMMARY Janus World Allocation Fund
Objective [Heading]rr_ObjectiveHeadingINVESTMENT OBJECTIVE
Objective, Primary [Text Block]rr_ObjectivePrimaryTextBlockJanus World Allocation Fund seeks long-term growth of capital with a secondary emphasis on income.
FEES AND EXPENSES OF THE FUNDjif277751_FundFeesAndExpensesAbstract 
Expense [Heading]rr_ExpenseHeadingFEES AND EXPENSES OF THE FUND
Expense Narrative [Text Block]rr_ExpenseNarrativeTextBlockThis 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.
Expense Breakpoint Discountsjif277751_ExpenseBreakpointDiscountsAbstract 
Expense Breakpoint Discounts [Text]rr_ExpenseBreakpointDiscountsFor 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 32 of the Fund’s Prospectus and in the “Purchases” section on page 64 of the Fund’s Statement of Additional Information.
Expense Breakpoint, Minimum Investment Required [Amount]rr_ExpenseBreakpointMinimumInvestmentRequiredAmount50,000
SHAREHOLDER FEESrr_ShareholderFeesAbstract 
Shareholder Fees Caption [Text]rr_ShareholderFeesCaptionSHAREHOLDER FEES (fees paid directly from your investment)
ANNUAL FUND OPERATING EXPENSESrr_OperatingExpensesAbstract 
Operating Expenses Caption [Text]rr_OperatingExpensesCaptionANNUAL 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 Terminationrr_FeeWaiverOrReimbursementOverAssetsDateOfTerminationNovember 1, 2012
EXAMPLE:rr_ExpenseExampleAbstract 
Expense Example [Heading]rr_ExpenseExampleHeadingEXAMPLE:
Expense Example Narrative [Text Block]rr_ExpenseExampleNarrativeTextBlockThe 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 [Heading]rr_ExpenseExampleByYearHeadingThe 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) without waivers remain the same. Although your actual costs may be higher or lower, based on these assumptions your costs would be:
Expense Example by, Year, Caption [Text]rr_ExpenseExampleByYearCaptionIf Shares are redeemed:
Expense Example, No Redemption:rr_ExpenseExampleNoRedemptionAbstract 
Expense Example, No Redemption, By Year, Caption [Text]rr_ExpenseExampleNoRedemptionByYearCaptionIf Shares are not redeemed:
Portfolio Turnover:jif277751_PortfolioTurnoverAltAbstract 
Portfolio Turnover [Heading]rr_PortfolioTurnoverHeadingPortfolio Turnover:
Portfolio Turnover [Text Block]rr_PortfolioTurnoverTextBlockThe 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 period, the Fund’s portfolio turnover rate was 71% of the average value of its portfolio.
Portfolio Turnover, Raterr_PortfolioTurnoverRate71.00%
Principal Investment Strategiesjif277751_PrincipalInvestmentStrategiesAbstract 
Strategy [Heading]rr_StrategyHeadingPRINCIPAL INVESTMENT STRATEGIES
Strategy Narrative [Text Block]rr_StrategyNarrativeTextBlock

The Fund pursues its investment objective by investing in a diversified portfolio of other Janus mutual funds (“underlying funds”) and securities that provide exposure to issuers located throughout the world. Through its investment in the underlying funds, the Fund invests in issuers from several different countries, including the United States, and may, under unusual circumstances, be invested in a single country. The Fund may also have significant exposure to emerging markets. Because it invests in other funds, the Fund is considered a “fund of funds.” The Fund utilizes Janus Capital’s proprietary process to allocate assets across the following three asset categories (as defined by Janus Capital):

• Core – The Core category seeks to provide market-like exposure by investing in funds that in turn primarily invest in a broad range of traditional asset classes such as large-, mid-, and small-cap stocks, U.S. and non-U.S. stocks, growth and value stocks, and investment-grade bonds. While not a primary strategy, the underlying funds may also invest in emerging market stocks and high-yield bonds. A primary goal of the underlying funds in the Core category is to provide shareholders with access to a broad range of investable assets in proportion to each asset class’ representation in today’s global, integrated market as determined by Janus Capital.

• Alpha – The Alpha category seeks to generate higher-than-market returns on a risk-adjusted basis by investing in funds that in turn invest in a broad range of traditional asset classes such as large-, mid-, and small-cap stocks, U.S. and non-U.S. stocks, growth and value stocks, emerging market stocks, investment-grade bonds, and high-yield bonds. Unlike funds in the Core category, the Alpha category is less focused on the asset class composition of the global market. Instead, the Alpha category is comprised of funds, unconstrained by asset class or investment style, that Janus Capital believes may generate higher-than-market returns over a market cycle.

• Alternative – The Alternative category is comprised of non-traditional investments with historically low correlation to the assets in the Core and Alpha categories, such as certain exchange-traded funds (“ETFs”), exchange-traded notes (“ETNs”), investments with hedge fund strategy exposure, commodities-related securities, real estate-related securities, and structured products.

The Fund attempts to maximize returns by investing the Fund’s assets in underlying funds investing in stocks (U.S. and non-U.S.), bonds, cash equivalents, alternative asset classes (such as real estate-related securities and commodity-related securities), and alternative investment strategies (such as leveraged and sector-based strategies). The target allocation of the Fund’s assets among underlying funds is based on an optimization process that utilizes quantitative analysis of a number of factors, such as historical risk, performance, fund classifications, and the relationship among underlying funds, as well as the portfolio manager’s judgment. Janus Capital analyzes Fund allocations on a regular basis in order to integrate current market data and reallocates on a quarterly basis.

The Fund’s 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 consults with a committee comprised of Janus Capital investment professionals (“Asset Allocation Committee”) to regularly review the process and the allocation of the Fund’s assets among the underlying funds to determine modifications to the underlying funds’ asset categories and/or weightings, or to substitute other underlying funds to emphasize and mitigate risk exposures that may arise as a result of the implementation of the allocations. The portfolio manager and Asset Allocation Committee normally review asset allocations on a quarterly basis. The portfolio manager oversees the implementation of trades on behalf of the Fund.

The Fund’s investments will be rebalanced to the identified optimal weightings on a quarterly basis, although more frequent changes can occur. The Fund’s asset class or category, category allocations, underlying funds, or underlying fund weightings may change without prior shareholder notice.

The Fund will normally allocate approximately 90% of its assets to Janus-managed mutual funds and approximately 10% to unaffiliated pooled investment vehicles (e.g., ETFs) and derivatives. For information on the potential underlying Janus funds currently available for investment by the Fund, including investment objectives and strategies, see “Investment Objectives and Strategies of the Underlying Funds” in Appendix A.

The Fund may invest in ETFs and ETNs to complement its investment in the underlying funds if there are asset classes not covered by the underlying funds or to better manage cash positions.

The Fund may invest its assets in derivatives, which are instruments that have a value derived from an underlying asset, such as equity securities, bonds, 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) including, but not limited to, swap agreements to earn income and enhance uncorrelated returns, to increase or decrease exposure to a particular market, to manage or adjust the risk profile of the Fund, or as alternatives to direct investments. For more information on the Fund’s use of derivatives, refer to the Fund’s shareholder reports and Form N-Q reports, which are filed with the Securities and Exchange Commission.

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 Risksjif277751_PrincipalInvestmentRisksAbstract 
Risk [Heading]rr_RiskHeadingPRINCIPAL 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 Janus Capital’s allocation of assets among the underlying funds and other securities, using the optimization process 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 concentrates.

Derivatives Risk. The Fund and 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 can be substantially greater than the derivative’s original cost, and can therefore involve leverage. Derivatives can be less liquid than other types of investments and entail the risk that the counterparty will default on its payment obligations.

Commodity-Linked Derivative Investment Risk. The Fund may invest in derivatives that have exposure to the commodities markets. This exposure may subject the 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.

Exchange-Traded Funds Risk. The Fund may purchase shares of 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 common stocks, 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. 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. 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.

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 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. Underlying funds investing in equity securities are subject to the risks associated with investments in common stocks, which tend to be more volatile than many other investment choices. 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. Through the Fund’s investments in underlying funds holding fixed-income securities, the Fund is subject to the risks associated with investments in a variety of fixed-income securities, which may be less volatile than underlying funds that invest most of their assets in common stocks; returns and yields will vary, and you could lose money. 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 their value 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.

Foreign Exposure Risk. The Fund and certain underlying funds may have significant exposure to foreign markets, including emerging markets, which can be more volatile than the U.S. markets. As a result, the Fund’s and 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 the Fund or an underlying fund has invested a significant amount of its assets may have a greater effect on the Fund’s or an underlying Fund’s performance than it would in a more geographically diversified portfolio. The Fund’s or 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 are exposed to 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, the Fund’s or 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 the Fund’s or an underlying fund’s investments. To the extent that the Fund or 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 the Fund or an underlying fund invests indirectly in foreign securities through various other investment vehicles including derivatives, which also involve specialized risks.

Mortgage-Backed Securities Risk. Mortgage-backed securities tend to be more sensitive to changes in interest rates than other types of 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.

Securities Lending Risk. Certain underlying funds may seek to earn additional income through lending their 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 underlying fund may experience delays and costs in recovering the security or gaining access to the collateral provided to collateralize the loan. If the underlying fund is unable to recover a security on loan, the underlying 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 underlying 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_RiskLoseMoneyThe biggest risk is that the Fund’s returns will vary, and you could lose money.
Risk Not Insured Depository Institution [Text]rr_RiskNotInsuredDepositoryInstitutionAn 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 INFORMATIONjif277751_FundPastPerformanceAbstract 
Bar Chart and Performance Table [Heading]rr_BarChartAndPerformanceTableHeadingPERFORMANCE 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 Modular Portfolio Construction® 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. 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.

Bar Chart Does Not Reflect Sales Loads [Text]rr_BarChartDoesNotReflectSalesLoadsThe 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.
Performance Additional Market Index [Text]rr_PerformanceAdditionalMarketIndexThe 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 Past Does Not Indicate Future [Text]rr_PerformancePastDoesNotIndicateFutureThe Fund’s past performance (before and after taxes) does not necessarily indicate how it will perform in the future.
Performance Table Closing [Text Block]rr_PerformanceTableClosingTextBlockUpdated performance information is available at janus.com/advisor/mutual-funds or by calling 1-877-335-2687.
Performance Availability Website Address [Text]rr_PerformanceAvailabilityWebSiteAddressjanus.com/advisor/mutual-funds
Performance Availability Phone [Text]rr_PerformanceAvailabilityPhone1-877-335-2687
Annual Total Returnsrr_BarChartTableAbstract 
Bar Chart [Heading]rr_BarChartHeadingAnnual Total Returns for Class I Shares (calendar year-end)
Bar Chart Closing [Text Block]rr_BarChartClosingTextBlock

Best Quarter:  Second Quarter 2009  14.90%          Worst Quarter:  First Quarter 2009 -3.20%

Year to Date Return, Labelrr_YearToDateReturnLabelThe Fund’s year-to-date return as of the calendar quarter ended September 30, 2011 was -12.02%.
Bar Chart, Year to Date Return, Daterr_BarChartYearToDateReturnDateSep. 30, 2011
Bar Chart, Year to Date Returnrr_BarChartYearToDateReturn(12.02%)
Average Annual Total Returnsrr_AverageAnnualReturnAbstract 
Captionrr_AverageAnnualReturnCaptionAverage Annual Total Returns (periods ended 12/31/10)
Performance Table Narrativerr_PerformanceTableNarrativeTextBlock

Effective September 30, 2011, the Fund changed its primary benchmark index from the Russell 3000® Index to the Morgan Stanley Capital International (“MSCI”) All Country World IndexSM. The MSCI All Country World IndexSM is an unmanaged, free float-adjusted, market capitalization weighted index composed of stocks of companies located in countries throughout the world. It is designed to measure equity market performance in global developed and emerging markets. The index includes reinvestment of dividends, net of foreign withholding taxes. In addition, the Fund changed its secondary benchmark index from the Dynamic Allocation Composite Index (which combined total returns from the Russell 3000® Index (50%), the Barclays Capital U.S. Aggregate Bond Index (25%), and the MSCI All Country World ex-U.S. IndexSM (25%)) to the World Allocation Index. The World Allocation Index is an internally-calculated, hypothetical combination of unmanaged indices that combines total returns from the MSCI All Country World IndexSM (65%) and the Barclays Capital Global Aggregate Bond Index (35%). Janus Capital believes that these changes provide a more appropriate representation of the Fund’s 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 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 Uses Highest Federal Raterr_PerformanceTableUsesHighestFederalRateAfter-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 Deferredrr_PerformanceTableNotRelevantToTaxDeferredActual 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_PerformanceTableOneClassOfAfterTaxShownAfter-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.
Janus World Allocation Fund | Class A, C, S, I, T Shares | Class A
 
SHAREHOLDER FEESrr_ShareholderFeesAbstract 
Shareholder Fees Column [Text]rr_ShareholderFeesColumnNameClass A
Maximum Sales Charge (load) Imposed on Purchases (as a percentage of offering price)rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice5.75%
Maximum Deferred Sales Charge (load) (as a percentage of the lower of original purchase price or redemption proceeds)rr_MaximumDeferredSalesChargeOverOther none
ANNUAL FUND OPERATING EXPENSESrr_OperatingExpensesAbstract 
Operating Expenses Column [Text]rr_OperatingExpensesColumnNameClass A
Management Feesrr_ManagementFeesOverAssets0.07%
Distribution/Service (12b-1) Feesrr_DistributionAndService12b1FeesOverAssets0.25%
Other Expensesrr_OtherExpensesOverAssets1.24%
Acquired Fund Fees and Expensesrr_AcquiredFundFeesAndExpensesOverAssets0.66%
Total Annual Fund Operating Expensesrr_ExpensesOverAssets2.22%[9]
Fee Waiverrr_FeeWaiverOrReimbursementOverAssets0.83%[9]
Net Annual Fund Operating Expenses After Fee Waiverrr_NetExpensesOverAssets1.39%[9]
EXAMPLE:rr_ExpenseExampleAbstract 
Expense Example, By Year, Column [Text]rr_ExpenseExampleByYearColumnNameClass A Shares
1 Yearrr_ExpenseExampleYear01787
3 Yearsrr_ExpenseExampleYear031,229
5 Yearsrr_ExpenseExampleYear051,696
10 Yearsrr_ExpenseExampleYear102,982
Expense Example, No Redemption:rr_ExpenseExampleNoRedemptionAbstract 
Expense Example, No Redemption, By Year, Column [Text]rr_ExpenseExampleNoRedemptionByYearColumnNameClass A Shares
1 Yearrr_ExpenseExampleNoRedemptionYear01787
3 Yearsrr_ExpenseExampleNoRedemptionYear031,229
5 Yearsrr_ExpenseExampleNoRedemptionYear051,696
10 Yearsrr_ExpenseExampleNoRedemptionYear102,982
Janus World Allocation Fund | Class A, C, S, I, T Shares | Class C
 
SHAREHOLDER FEESrr_ShareholderFeesAbstract 
Shareholder Fees Column [Text]rr_ShareholderFeesColumnNameClass 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_MaximumDeferredSalesChargeOverOther1.00%
ANNUAL FUND OPERATING EXPENSESrr_OperatingExpensesAbstract 
Operating Expenses Column [Text]rr_OperatingExpensesColumnNameClass C
Management Feesrr_ManagementFeesOverAssets0.07%
Distribution/Service (12b-1) Feesrr_DistributionAndService12b1FeesOverAssets1.00%
Other Expensesrr_OtherExpensesOverAssets1.36%
Acquired Fund Fees and Expensesrr_AcquiredFundFeesAndExpensesOverAssets0.66%
Total Annual Fund Operating Expensesrr_ExpensesOverAssets3.09%[9]
Fee Waiverrr_FeeWaiverOrReimbursementOverAssets0.95%[9]
Net Annual Fund Operating Expenses After Fee Waiverrr_NetExpensesOverAssets2.14%[9]
EXAMPLE:rr_ExpenseExampleAbstract 
Expense Example, By Year, Column [Text]rr_ExpenseExampleByYearColumnNameClass C Shares
1 Yearrr_ExpenseExampleYear01412
3 Yearsrr_ExpenseExampleYear03954
5 Yearsrr_ExpenseExampleYear051,620
10 Yearsrr_ExpenseExampleYear103,402
Expense Example, No Redemption:rr_ExpenseExampleNoRedemptionAbstract 
Expense Example, No Redemption, By Year, Column [Text]rr_ExpenseExampleNoRedemptionByYearColumnNameClass C Shares
1 Yearrr_ExpenseExampleNoRedemptionYear01312
3 Yearsrr_ExpenseExampleNoRedemptionYear03954
5 Yearsrr_ExpenseExampleNoRedemptionYear051,620
10 Yearsrr_ExpenseExampleNoRedemptionYear103,402
Janus World Allocation Fund | Class A, C, S, I, T Shares | Class I
 
SHAREHOLDER FEESrr_ShareholderFeesAbstract 
Shareholder Fees Column [Text]rr_ShareholderFeesColumnNameClass 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
ANNUAL FUND OPERATING EXPENSESrr_OperatingExpensesAbstract 
Operating Expenses Column [Text]rr_OperatingExpensesColumnNameClass I
Management Feesrr_ManagementFeesOverAssets0.07%
Distribution/Service (12b-1) Feesrr_DistributionAndService12b1FeesOverAssets none
Other Expensesrr_OtherExpensesOverAssets1.34%
Acquired Fund Fees and Expensesrr_AcquiredFundFeesAndExpensesOverAssets0.66%
Total Annual Fund Operating Expensesrr_ExpensesOverAssets2.07%[9]
Fee Waiverrr_FeeWaiverOrReimbursementOverAssets0.93%[9]
Net Annual Fund Operating Expenses After Fee Waiverrr_NetExpensesOverAssets1.14%[9]
EXAMPLE:rr_ExpenseExampleAbstract 
Expense Example, By Year, Column [Text]rr_ExpenseExampleByYearColumnNameClass I Shares
1 Yearrr_ExpenseExampleYear01210
3 Yearsrr_ExpenseExampleYear03649
5 Yearsrr_ExpenseExampleYear051,114
10 Yearsrr_ExpenseExampleYear102,400
Expense Example, No Redemption:rr_ExpenseExampleNoRedemptionAbstract 
Expense Example, No Redemption, By Year, Column [Text]rr_ExpenseExampleNoRedemptionByYearColumnNameClass I Shares
1 Yearrr_ExpenseExampleNoRedemptionYear01210
3 Yearsrr_ExpenseExampleNoRedemptionYear03649
5 Yearsrr_ExpenseExampleNoRedemptionYear051,114
10 Yearsrr_ExpenseExampleNoRedemptionYear102,400
Annual Total Returnsrr_BarChartTableAbstract 
2009rr_AnnualReturn200928.87%
2010rr_AnnualReturn201011.54%
Highest Quarterly Return, Labelrr_HighestQuarterlyReturnLabelBest Quarter:
Highest Quarterly Return, Daterr_BarChartHighestQuarterlyReturnDateJun. 30, 2009
Highest Quarterly Returnrr_BarChartHighestQuarterlyReturn14.90%
Lowest Quarterly Return, Labelrr_LowestQuarterlyReturnLabelWorst Quarter:
Lowest Quarterly Return, Daterr_BarChartLowestQuarterlyReturnDateMar. 31, 2009
Lowest Quarterly Returnrr_BarChartLowestQuarterlyReturn(3.20%)
Janus World Allocation Fund | Class A, C, S, I, T Shares | Class S
 
SHAREHOLDER FEESrr_ShareholderFeesAbstract 
Shareholder Fees Column [Text]rr_ShareholderFeesColumnNameClass 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
ANNUAL FUND OPERATING EXPENSESrr_OperatingExpensesAbstract 
Operating Expenses Column [Text]rr_OperatingExpensesColumnNameClass S
Management Feesrr_ManagementFeesOverAssets0.07%
Distribution/Service (12b-1) Feesrr_DistributionAndService12b1FeesOverAssets0.25%
Other Expensesrr_OtherExpensesOverAssets1.47%
Acquired Fund Fees and Expensesrr_AcquiredFundFeesAndExpensesOverAssets0.66%
Total Annual Fund Operating Expensesrr_ExpensesOverAssets2.45%[9]
Fee Waiverrr_FeeWaiverOrReimbursementOverAssets0.81%[9]
Net Annual Fund Operating Expenses After Fee Waiverrr_NetExpensesOverAssets1.64%[9]
EXAMPLE:rr_ExpenseExampleAbstract 
Expense Example, By Year, Column [Text]rr_ExpenseExampleByYearColumnNameClass S Shares
1 Yearrr_ExpenseExampleYear01248
3 Yearsrr_ExpenseExampleYear03764
5 Yearsrr_ExpenseExampleYear051,306
10 Yearsrr_ExpenseExampleYear102,786
Expense Example, No Redemption:rr_ExpenseExampleNoRedemptionAbstract 
Expense Example, No Redemption, By Year, Column [Text]rr_ExpenseExampleNoRedemptionByYearColumnNameClass S Shares
1 Yearrr_ExpenseExampleNoRedemptionYear01248
3 Yearsrr_ExpenseExampleNoRedemptionYear03764
5 Yearsrr_ExpenseExampleNoRedemptionYear051,306
10 Yearsrr_ExpenseExampleNoRedemptionYear102,786
Janus World Allocation Fund | Class A, C, S, I, T Shares | Class T
 
SHAREHOLDER FEESrr_ShareholderFeesAbstract 
Shareholder Fees Column [Text]rr_ShareholderFeesColumnNameClass 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
ANNUAL FUND OPERATING EXPENSESrr_OperatingExpensesAbstract 
Operating Expenses Column [Text]rr_OperatingExpensesColumnNameClass T
Management Feesrr_ManagementFeesOverAssets0.07%
Distribution/Service (12b-1) Feesrr_DistributionAndService12b1FeesOverAssets none
Other Expensesrr_OtherExpensesOverAssets1.32%
Acquired Fund Fees and Expensesrr_AcquiredFundFeesAndExpensesOverAssets0.66%
Total Annual Fund Operating Expensesrr_ExpensesOverAssets2.05%[9]
Fee Waiverrr_FeeWaiverOrReimbursementOverAssets0.66%[9]
Net Annual Fund Operating Expenses After Fee Waiverrr_NetExpensesOverAssets1.39%[9]
EXAMPLE:rr_ExpenseExampleAbstract 
Expense Example, By Year, Column [Text]rr_ExpenseExampleByYearColumnNameClass T Shares
1 Yearrr_ExpenseExampleYear01208
3 Yearsrr_ExpenseExampleYear03643
5 Yearsrr_ExpenseExampleYear051,103
10 Yearsrr_ExpenseExampleYear102,379
Expense Example, No Redemption:rr_ExpenseExampleNoRedemptionAbstract 
Expense Example, No Redemption, By Year, Column [Text]rr_ExpenseExampleNoRedemptionByYearColumnNameClass T Shares
1 Yearrr_ExpenseExampleNoRedemptionYear01208
3 Yearsrr_ExpenseExampleNoRedemptionYear03643
5 Yearsrr_ExpenseExampleNoRedemptionYear051,103
10 Yearsrr_ExpenseExampleNoRedemptionYear102,379
Janus World Allocation Fund | Class A, C, S, I, T Shares | Return Before Taxes | Class A
 
Average Annual Total Returnsrr_AverageAnnualReturnAbstract 
Columnrr_AverageAnnualReturnColumnNameClass A Shares
Labelrr_AverageAnnualReturnLabelReturn Before Taxes[3]
1 Yearrr_AverageAnnualReturnYear015.12%
Since Inceptionrr_AverageAnnualReturnSinceInception0.99%
Inception Daterr_AverageAnnualReturnInceptionDateSep. 03, 2008
Janus World Allocation Fund | Class A, C, S, I, T Shares | Return Before Taxes | Class C
 
Average Annual Total Returnsrr_AverageAnnualReturnAbstract 
Columnrr_AverageAnnualReturnColumnNameClass C Shares
Labelrr_AverageAnnualReturnLabelReturn Before Taxes[4]
1 Yearrr_AverageAnnualReturnYear019.59%
Since Inceptionrr_AverageAnnualReturnSinceInception3.02%
Inception Daterr_AverageAnnualReturnInceptionDateSep. 03, 2008
Janus World Allocation Fund | Class A, C, S, I, T Shares | Return Before Taxes | Class I
 
Average Annual Total Returnsrr_AverageAnnualReturnAbstract 
Columnrr_AverageAnnualReturnColumnNameClass I Shares
Labelrr_AverageAnnualReturnLabelReturn Before Taxes
1 Yearrr_AverageAnnualReturnYear0111.54%
Since Inceptionrr_AverageAnnualReturnSinceInception3.74%
Inception Daterr_AverageAnnualReturnInceptionDateSep. 03, 2008
Janus World Allocation Fund | Class A, C, S, I, T Shares | Return Before Taxes | Class S
 
Average Annual Total Returnsrr_AverageAnnualReturnAbstract 
Columnrr_AverageAnnualReturnColumnNameClass S Shares
Labelrr_AverageAnnualReturnLabelReturn Before Taxes
1 Yearrr_AverageAnnualReturnYear0111.02%
Since Inceptionrr_AverageAnnualReturnSinceInception3.40%
Inception Daterr_AverageAnnualReturnInceptionDateSep. 03, 2008
Janus World Allocation Fund | Class A, C, S, I, T Shares | Return Before Taxes | Class T
 
Average Annual Total Returnsrr_AverageAnnualReturnAbstract 
Columnrr_AverageAnnualReturnColumnNameClass T Shares
Labelrr_AverageAnnualReturnLabelReturn Before Taxes
1 Yearrr_AverageAnnualReturnYear0111.48%
Since Inceptionrr_AverageAnnualReturnSinceInception3.63%
Inception Daterr_AverageAnnualReturnInceptionDateSep. 03, 2008
Janus World Allocation Fund | Class A, C, S, I, T Shares | Return After Taxes on Distributions | Class I
 
Average Annual Total Returnsrr_AverageAnnualReturnAbstract 
Columnrr_AverageAnnualReturnColumnNameClass I Shares
Labelrr_AverageAnnualReturnLabelReturn After Taxes on Distributions
1 Yearrr_AverageAnnualReturnYear0110.61%
Since Inceptionrr_AverageAnnualReturnSinceInception3.09%
Inception Daterr_AverageAnnualReturnInceptionDateSep. 03, 2008
Janus World Allocation Fund | Class A, C, S, I, T Shares | Return After Taxes on Distributions and Sale of Fund Shares | Class I
 
Average Annual Total Returnsrr_AverageAnnualReturnAbstract 
Columnrr_AverageAnnualReturnColumnNameClass I Shares
Labelrr_AverageAnnualReturnLabelReturn After Taxes on Distributions and Sale of Fund Shares[5]
1 Yearrr_AverageAnnualReturnYear018.08%
Since Inceptionrr_AverageAnnualReturnSinceInception2.93%
Inception Daterr_AverageAnnualReturnInceptionDateSep. 03, 2008
Janus World Allocation Fund | Class A, C, S, I, T Shares | Morgan Stanley Capital International All Country World Index℠ (net)
 
Average Annual Total Returnsrr_AverageAnnualReturnAbstract 
Labelrr_AverageAnnualReturnLabelMorgan Stanley Capital International All Country World IndexSM (net)
Index No Deduction for Fees, Expenses, Taxes [Text]rr_IndexNoDeductionForFeesExpensesTaxes(reflects no deduction for expenses, fees, or taxes)
1 Yearrr_AverageAnnualReturnYear0112.67%
Since Inceptionrr_AverageAnnualReturnSinceInception2.28%
Inception Daterr_AverageAnnualReturnInceptionDateSep. 03, 2008
Janus World Allocation Fund | Class A, C, S, I, T Shares | World Allocation Index
 
Average Annual Total Returnsrr_AverageAnnualReturnAbstract 
Labelrr_AverageAnnualReturnLabelWorld Allocation Index
Index No Deduction for Fees, Expenses, Taxes [Text]rr_IndexNoDeductionForFeesExpensesTaxes(reflects no deduction for expenses, fees, or taxes)
1 Yearrr_AverageAnnualReturnYear0110.50%
Since Inceptionrr_AverageAnnualReturnSinceInception4.46%
Inception Daterr_AverageAnnualReturnInceptionDateSep. 03, 2008
Janus World Allocation Fund | Class A, C, S, I, T Shares | Russell 3000® Index
 
Average Annual Total Returnsrr_AverageAnnualReturnAbstract 
Labelrr_AverageAnnualReturnLabelRussell 3000® Index
Index No Deduction for Fees, Expenses, Taxes [Text]rr_IndexNoDeductionForFeesExpensesTaxes(reflects no deduction for expenses, fees, or taxes)
1 Yearrr_AverageAnnualReturnYear0117.64%
Since Inceptionrr_AverageAnnualReturnSinceInception2.44%
Inception Daterr_AverageAnnualReturnInceptionDateSep. 03, 2008
Janus World Allocation Fund | Class A, C, S, I, T Shares | Dynamic Allocation Composite Index
 
Average Annual Total Returnsrr_AverageAnnualReturnAbstract 
Labelrr_AverageAnnualReturnLabelDynamic Allocation Composite Index
Index No Deduction for Fees, Expenses, Taxes [Text]rr_IndexNoDeductionForFeesExpensesTaxes(reflects no deduction for expenses, fees, or taxes)
1 Yearrr_AverageAnnualReturnYear0113.34%
Since Inceptionrr_AverageAnnualReturnSinceInception4.31%
Inception Daterr_AverageAnnualReturnInceptionDateSep. 03, 2008
Janus Real Return Allocation Fund | Class A, C, S, I, T Shares
 
Risk/Return:rr_RiskReturnAbstract 
Risk/Return [Heading]rr_RiskReturnHeadingFUND SUMMARY Janus Real Return Allocation Fund
Objective [Heading]rr_ObjectiveHeadingINVESTMENT OBJECTIVE
Objective, Primary [Text Block]rr_ObjectivePrimaryTextBlockJanus Real Return Allocation Fund seeks real return consistent with preservation of capital.
FEES AND EXPENSES OF THE FUNDjif277751_FundFeesAndExpensesAbstract 
Expense [Heading]rr_ExpenseHeadingFEES AND EXPENSES OF THE FUND
Expense Narrative [Text Block]rr_ExpenseNarrativeTextBlockThis 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.
Expense Breakpoint Discountsjif277751_ExpenseBreakpointDiscountsAbstract 
Expense Breakpoint Discounts [Text]rr_ExpenseBreakpointDiscountsFor 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 33 of the Fund’s Prospectus and in the “Purchases” section on page 60 of the Fund’s Statement of Additional Information.
Expense Breakpoint, Minimum Investment Required [Amount]rr_ExpenseBreakpointMinimumInvestmentRequiredAmount50,000
SHAREHOLDER FEESrr_ShareholderFeesAbstract 
Shareholder Fees Caption [Text]rr_ShareholderFeesCaptionSHAREHOLDER FEES (fees paid directly from your investment)
ANNUAL FUND OPERATING EXPENSESrr_OperatingExpensesAbstract 
Operating Expenses Caption [Text]rr_OperatingExpensesCaptionANNUAL FUND OPERATING EXPENSES (expenses that you pay each year as a percentage of the value of your investment)
Other Expenses, New Fund, Based on Estimates [Text]rr_OtherExpensesNewFundBasedOnEstimatesSince the Fund is new, Other Expenses are based on the estimated expenses that the Fund expects to incur in its initial fiscal period.
Fee Waiver or Reimbursement over Assets, Date of Terminationrr_FeeWaiverOrReimbursementOverAssetsDateOfTerminationNovember 1, 2012
EXAMPLE:rr_ExpenseExampleAbstract 
Expense Example [Heading]rr_ExpenseExampleHeadingEXAMPLE:
Expense Example Narrative [Text Block]rr_ExpenseExampleNarrativeTextBlockThe following Example is based on expenses without waivers except for the waiver of the management fee paid by the subsidiary (which is included under Fee Waiver in the table above). 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 [Heading]rr_ExpenseExampleByYearHeadingThe 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 by, Year, Caption [Text]rr_ExpenseExampleByYearCaptionIf Shares are redeemed:
Expense Example, No Redemption:rr_ExpenseExampleNoRedemptionAbstract 
Expense Example, No Redemption, By Year, Caption [Text]rr_ExpenseExampleNoRedemptionByYearCaptionIf Shares are not redeemed:
Portfolio Turnover:jif277751_PortfolioTurnoverAltAbstract 
Portfolio Turnover [Heading]rr_PortfolioTurnoverHeadingPortfolio Turnover:
Portfolio Turnover [Text Block]rr_PortfolioTurnoverTextBlockThe 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.
Principal Investment Strategiesjif277751_PrincipalInvestmentStrategiesAbstract 
Strategy [Heading]rr_StrategyHeadingPRINCIPAL INVESTMENT STRATEGIES
Strategy Narrative [Text Block]rr_StrategyNarrativeTextBlock

Under normal market conditions, the Fund seeks to allocate its assets among the following inflation-related investment categories: global inflation-linked securities, commodity-linked investments, emerging market debt, emerging market equity, global real estate, and short-duration debt. Inflation-related investment categories are those which may provide what is known as “real return,” or a rate of return above the rate of inflation over a market cycle. The Fund has wide flexibility to allocate assets across categories and may, at times, allocate assets to less than all categories. The Fund’s Allocation Committee utilizes a “top down” analysis of macroeconomic factors to determine the overall allocation to each of the Fund’s investment categories. Individual portfolio managers generally utilize a “bottom up” approach in choosing investments where the portfolio managers look at companies one at a time to determine if an investment is an attractive investment opportunity and if it is consistent with the Fund’s investment policies, but may also consider macroeconomic factors. Due to the nature of the securities in which the Fund invests and the allocation process, it may have relatively high portfolio turnover compared to other funds.

The Fund’s investment in global inflation-linked securities will generally consist of inflation-indexed bonds issued by both governments and corporations, and may include non-U.S. issuers, including emerging markets. Such investments may include, but are not limited to, Treasury Inflation-Protected Securities, also known as TIPS. The Fund may utilize inflation index swaps to hedge against unexpected changes in the rate of inflation as measured by an inflation index such as the Consumer Price Index. The Fund may utilize reverse repurchase agreements to generate income as part of its inflation-related strategies. Proceeds from reverse repurchase transactions may be invested in other securities or instruments in an effort to increase the Fund’s investment returns.

To seek exposure to the commodities markets, the Fund may invest in 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 will seek to gain exposure to the commodity markets, in whole or in part, through investments 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 of the Fund. The Subsidiary invests in commodity-linked investments and other investments which may serve as margin or collateral for the Subsidiary’s derivative positions.

The Fund’s investments in emerging market debt securities and short-duration debt securities may include, but are not limited to, corporate bonds, government bonds, municipal bonds, convertible bonds, mortgage-backed securities, zero-coupon bonds, and agency securities. The Fund may invest in debt securities of issuers in a number of developed market countries, which may include the United States. The Fund may invest in debt securities with a range of maturities from short- to long-term. The Fund may invest up to 25% of its net assets in high-yield/high-risk debt securities.

The Fund’s investments in emerging market equity securities include securities of issuers that (i) are primarily listed on the trading market of an emerging market country; (ii) are incorporated or have their principal business activities in an emerging market country; or (iii) derive 50% or more of their revenues from, or have 50% or more of their assets in, an emerging market country. An emerging market country is any country that has been determined by an international organization, such as the World Bank, to have a low to middle income economy and/or any country that is not included in the Morgan Stanley Capital International World IndexSM, which measures the equity market performance of developed markets.

The Fund may invest in equity and debt securities of U.S. and non-U.S. 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, real estate investment trusts (“REITs”), and similar REIT-like entities such as foreign entities that have REIT characteristics.

In addition to the allocations above, the Fund may invest in other inflation-related investment categories, which may include investments in money market instruments, buy backs or dollar rolls, other securitized debt products, preferred stock, bank loans, private placements, exchange-traded notes, and other investment companies, including exchange-traded funds (“ETFs”), and commodity-related ETFs. The Fund may invest in companies of any market capitalization. The Fund’s investments may be denominated in local currency or U.S. dollar-denominated. The Fund may lend portfolio securities on a short-term or long-term basis, in an amount to up to 1/3 of its assets as determined at the time of the loan origination.

In addition to commodities-linked derivative instruments and inflation index swaps, the Fund may also invest its assets in derivative instruments that have a value derived from other underlying assets, such as stocks, bonds, currencies, interest rates or market indices. The Fund may invest in swaps to gain access to foreign markets, including circumstances where direct investment may be restricted or unavailable. The Fund may also invest in derivative instruments, such as forward currency contracts, to hedge the value of the Fund’s portfolio against the Fund’s benchmark index. The Fund may also invest in derivative instruments (by taking long and/or short positions) for other purposes, including hedging, 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, 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. For more information on the Fund’s use of derivatives, refer to the Fund’s shareholder reports and Form N-Q reports, which are filed with the Securities and Exchange Commission.

Principal Investment Risksjif277751_PrincipalInvestmentRisksAbstract 
Risk [Heading]rr_RiskHeadingPRINCIPAL 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 asset allocation portfolio, which includes common stocks, commodity-linked investments, emerging market securities, and derivatives. Such investments tend to be more volatile than many other investment choices.

Management Risk. The Fund’s ability to achieve its investment objective depends largely upon successful evaluation of the risk, potential returns, and correlation among the various investment categories in which the Fund may invest, such as inflation-linked securities, commodity-related investments, emerging market debt, emerging market equity, global real estate, and short-duration debt. You could lose money on your investment in the Fund as a result of these allocations. Additionally, Armored Wolf has a limited history of operations. 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 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.

Inflation-Linked Securities Risk. Because of their inflation adjustment feature, inflation-linked bonds typically have lower yields than conventional fixed-rate bonds. In addition, inflation-linked bonds also normally decline in price when real interest rates rise. In the event of deflation, in which prices decline over time, the principal and income of inflation-linked bonds would likely decline, resulting in losses to the Fund. Inflation-linked securities such as inflation index swaps are also subject to inflation risk, where such 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.

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.

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 Fund has applied for a private letter ruling from the Internal Revenue Service (“IRS”) with respect to the tax treatment of income from its investment in the Subsidiary. 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, 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.

Leverage Risk. Gains or losses from a derivative can be substantially greater than the derivative’s original cost, and can therefore involve leverage. In particular, certain commodity-linked derivatives or commodity-related ETFs may subject the Fund to leveraged market exposure to commodities. Leverage also occurs when the Fund increases its assets available for investment through borrowings or similar transactions. The Fund’s use of leverage can magnify the effect of any gains or losses, causing the Fund to be more volatile than if it had not been leveraged. There is no assurance that any leveraging strategy will be successful.

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.

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. Such leveraging transactions make the value of an investment in the Fund more volatile and increases 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.

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 can be substantially greater than the derivative’s original cost, and can therefore involve 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.

Foreign Exposure Risk. The Fund normally has significant exposure to foreign markets, including 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. 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.

Emerging Markets Risk. The risks of foreign investing mentioned above are heightened when investing in emerging markets. Emerging markets securities are exposed to 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, 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. As of June 30, 2011, approximately 6.8% of the Fund’s investments were in emerging markets.

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 their value 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.

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.

Mortgage-Backed Securities Risk. Mortgage-backed securities tend to be more sensitive to changes in interest rates than other types of 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.

Real Estate Risk. An investment in the Fund may be subject to many of the same risks as a direct investment in real estate. The value of securities of issuers in the real estate and real estate-related industries, including REITs, 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 issuer. These factors may impact the Fund’s investments in foreign real estate markets differently than U.S. real estate markets.

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.

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 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 index 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 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.

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.

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 return. 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.

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_RiskLoseMoneyThe biggest risk is that the Fund’s returns will vary, and you could lose money.
Risk Nondiversified Status [Text]rr_RiskNondiversifiedStatusNondiversification 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_RiskNotInsuredDepositoryInstitutionAn 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 INFORMATIONjif277751_FundPastPerformanceAbstract 
Bar Chart and Performance Table [Heading]rr_BarChartAndPerformanceTableHeadingPERFORMANCE INFORMATION
Performance Narrative [Text Block]rr_PerformanceNarrativeTextBlockThe Fund does not have a full calendar year of operations. Performance information for certain periods will be included in the Fund’s first annual and/or semiannual report.
Performance One Year or Less [Text]rr_PerformanceOneYearOrLessThe Fund does not have a full calendar year of operations.
Janus Real Return Allocation Fund | Class A, C, S, I, T Shares | Class A
 
SHAREHOLDER FEESrr_ShareholderFeesAbstract 
Shareholder Fees Column [Text]rr_ShareholderFeesColumnNameClass A
Maximum Sales Charge (load) Imposed on Purchases (as a percentage of offering price)rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice5.75%
Maximum Deferred Sales Charge (load) (as a percentage of the lower of original purchase price or redemption proceeds)rr_MaximumDeferredSalesChargeOverOther none
ANNUAL FUND OPERATING EXPENSESrr_OperatingExpensesAbstract 
Operating Expenses Column [Text]rr_OperatingExpensesColumnNameClass A
Management Feesrr_ManagementFeesOverAssets0.75%[11]
Distribution/Service (12b-1) Feesrr_DistributionAndService12b1FeesOverAssets0.25%
Other Expensesrr_OtherExpensesOverAssets1.17%[12]
Other Expenses of the Fundrr_Component1OtherExpensesOverAssets1.05%
Other Expenses of the Subsidiaryrr_Component2OtherExpensesOverAssets0.12%
Total Annual Fund Operating Expensesrr_ExpensesOverAssets2.17%[13]
Fee Waiverrr_FeeWaiverOrReimbursementOverAssets0.90%[13]
Net Annual Fund Operating Expenses After Fee Waiverrr_NetExpensesOverAssets1.27%[13]
EXAMPLE:rr_ExpenseExampleAbstract 
Expense Example, By Year, Column [Text]rr_ExpenseExampleByYearColumnNameClass A Shares
1 Yearrr_ExpenseExampleYear01782
3 Yearsrr_ExpenseExampleYear031,214
Expense Example, No Redemption:rr_ExpenseExampleNoRedemptionAbstract 
Expense Example, No Redemption, By Year, Column [Text]rr_ExpenseExampleNoRedemptionByYearColumnNameClass A Shares
1 Yearrr_ExpenseExampleNoRedemptionYear01782
3 Yearsrr_ExpenseExampleNoRedemptionYear031,214
Janus Real Return Allocation Fund | Class A, C, S, I, T Shares | Class C
 
SHAREHOLDER FEESrr_ShareholderFeesAbstract 
Shareholder Fees Column [Text]rr_ShareholderFeesColumnNameClass 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_MaximumDeferredSalesChargeOverOther1.00%
ANNUAL FUND OPERATING EXPENSESrr_OperatingExpensesAbstract 
Operating Expenses Column [Text]rr_OperatingExpensesColumnNameClass C
Management Feesrr_ManagementFeesOverAssets0.75%[11]
Distribution/Service (12b-1) Feesrr_DistributionAndService12b1FeesOverAssets1.00%
Other Expensesrr_OtherExpensesOverAssets1.19%[12]
Other Expenses of the Fundrr_Component1OtherExpensesOverAssets1.07%
Other Expenses of the Subsidiaryrr_Component2OtherExpensesOverAssets0.12%
Total Annual Fund Operating Expensesrr_ExpensesOverAssets2.94%[13]
Fee Waiverrr_FeeWaiverOrReimbursementOverAssets0.92%[13]
Net Annual Fund Operating Expenses After Fee Waiverrr_NetExpensesOverAssets2.02%[13]
EXAMPLE:rr_ExpenseExampleAbstract 
Expense Example, By Year, Column [Text]rr_ExpenseExampleByYearColumnNameClass C Shares
1 Yearrr_ExpenseExampleYear01397
3 Yearsrr_ExpenseExampleYear03909
Expense Example, No Redemption:rr_ExpenseExampleNoRedemptionAbstract 
Expense Example, No Redemption, By Year, Column [Text]rr_ExpenseExampleNoRedemptionByYearColumnNameClass C Shares
1 Yearrr_ExpenseExampleNoRedemptionYear01297
3 Yearsrr_ExpenseExampleNoRedemptionYear03909
Janus Real Return Allocation Fund | Class A, C, S, I, T Shares | Class I
 
SHAREHOLDER FEESrr_ShareholderFeesAbstract 
Shareholder Fees Column [Text]rr_ShareholderFeesColumnNameClass 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
ANNUAL FUND OPERATING EXPENSESrr_OperatingExpensesAbstract 
Operating Expenses Column [Text]rr_OperatingExpensesColumnNameClass I
Management Feesrr_ManagementFeesOverAssets0.75%[11]
Distribution/Service (12b-1) Feesrr_DistributionAndService12b1FeesOverAssets none
Other Expensesrr_OtherExpensesOverAssets1.08%[12]
Other Expenses of the Fundrr_Component1OtherExpensesOverAssets0.96%
Other Expenses of the Subsidiaryrr_Component2OtherExpensesOverAssets0.12%
Total Annual Fund Operating Expensesrr_ExpensesOverAssets1.83%[13]
Fee Waiverrr_FeeWaiverOrReimbursementOverAssets0.81%[13]
Net Annual Fund Operating Expenses After Fee Waiverrr_NetExpensesOverAssets1.02%[13]
EXAMPLE:rr_ExpenseExampleAbstract 
Expense Example, By Year, Column [Text]rr_ExpenseExampleByYearColumnNameClass I Shares
1 Yearrr_ExpenseExampleYear01186
3 Yearsrr_ExpenseExampleYear03575
Expense Example, No Redemption:rr_ExpenseExampleNoRedemptionAbstract 
Expense Example, No Redemption, By Year, Column [Text]rr_ExpenseExampleNoRedemptionByYearColumnNameClass I Shares
1 Yearrr_ExpenseExampleNoRedemptionYear01186
3 Yearsrr_ExpenseExampleNoRedemptionYear03575
Janus Real Return Allocation Fund | Class A, C, S, I, T Shares | Class S
 
SHAREHOLDER FEESrr_ShareholderFeesAbstract 
Shareholder Fees Column [Text]rr_ShareholderFeesColumnNameClass 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
ANNUAL FUND OPERATING EXPENSESrr_OperatingExpensesAbstract 
Operating Expenses Column [Text]rr_OperatingExpensesColumnNameClass S
Management Feesrr_ManagementFeesOverAssets0.75%[11]
Distribution/Service (12b-1) Feesrr_DistributionAndService12b1FeesOverAssets0.25%
Other Expensesrr_OtherExpensesOverAssets1.31%[12]
Other Expenses of the Fundrr_Component1OtherExpensesOverAssets1.19%
Other Expenses of the Subsidiaryrr_Component2OtherExpensesOverAssets0.12%
Total Annual Fund Operating Expensesrr_ExpensesOverAssets2.31%[13]
Fee Waiverrr_FeeWaiverOrReimbursementOverAssets0.79%[13]
Net Annual Fund Operating Expenses After Fee Waiverrr_NetExpensesOverAssets1.52%[13]
EXAMPLE:rr_ExpenseExampleAbstract 
Expense Example, By Year, Column [Text]rr_ExpenseExampleByYearColumnNameClass S Shares
1 Yearrr_ExpenseExampleYear01234
3 Yearsrr_ExpenseExampleYear03721
Expense Example, No Redemption:rr_ExpenseExampleNoRedemptionAbstract 
Expense Example, No Redemption, By Year, Column [Text]rr_ExpenseExampleNoRedemptionByYearColumnNameClass S Shares
1 Yearrr_ExpenseExampleNoRedemptionYear01234
3 Yearsrr_ExpenseExampleNoRedemptionYear03721
Janus Real Return Allocation Fund | Class A, C, S, I, T Shares | Class T
 
SHAREHOLDER FEESrr_ShareholderFeesAbstract 
Shareholder Fees Column [Text]rr_ShareholderFeesColumnNameClass 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
ANNUAL FUND OPERATING EXPENSESrr_OperatingExpensesAbstract 
Operating Expenses Column [Text]rr_OperatingExpensesColumnNameClass T
Management Feesrr_ManagementFeesOverAssets0.75%[11]
Distribution/Service (12b-1) Feesrr_DistributionAndService12b1FeesOverAssets none
Other Expensesrr_OtherExpensesOverAssets1.31%[12]
Other Expenses of the Fundrr_Component1OtherExpensesOverAssets1.19%
Other Expenses of the Subsidiaryrr_Component2OtherExpensesOverAssets0.12%
Total Annual Fund Operating Expensesrr_ExpensesOverAssets2.06%[13]
Fee Waiverrr_FeeWaiverOrReimbursementOverAssets0.79%[13]
Net Annual Fund Operating Expenses After Fee Waiverrr_NetExpensesOverAssets1.27%[13]
EXAMPLE:rr_ExpenseExampleAbstract 
Expense Example, By Year, Column [Text]rr_ExpenseExampleByYearColumnNameClass T Shares
1 Yearrr_ExpenseExampleYear01209
3 Yearsrr_ExpenseExampleYear03645
Expense Example, No Redemption:rr_ExpenseExampleNoRedemptionAbstract 
Expense Example, No Redemption, By Year, Column [Text]rr_ExpenseExampleNoRedemptionByYearColumnNameClass T Shares
1 Yearrr_ExpenseExampleNoRedemptionYear01209
3 Yearsrr_ExpenseExampleNoRedemptionYear03645
Janus Real Return Allocation Fund | Class D Shares
 
Risk/Return:rr_RiskReturnAbstract 
Risk/Return [Heading]rr_RiskReturnHeadingFUND SUMMARY Janus Real Return Allocation Fund
Objective [Heading]rr_ObjectiveHeadingINVESTMENT OBJECTIVE
Objective, Primary [Text Block]rr_ObjectivePrimaryTextBlockJanus Real Return Allocation Fund seeks real return consistent with preservation of capital.
FEES AND EXPENSES OF THE FUNDjif277751_FundFeesAndExpensesAbstract 
Expense [Heading]rr_ExpenseHeadingFEES AND EXPENSES OF THE FUND
Expense Narrative [Text Block]rr_ExpenseNarrativeTextBlockThis table describes the fees and expenses that you may pay if you buy and hold Shares of the Fund.
ANNUAL FUND OPERATING EXPENSESrr_OperatingExpensesAbstract 
Operating Expenses Caption [Text]rr_OperatingExpensesCaptionANNUAL FUND OPERATING EXPENSES (expenses that you pay each year as a percentage of the value of your investment)
Other Expenses, New Fund, Based on Estimates [Text]rr_OtherExpensesNewFundBasedOnEstimatesSince the Fund is new, Other Expenses are based on the estimated expenses that the Fund expects to incur in its initial fiscal period.
Fee Waiver or Reimbursement over Assets, Date of Terminationrr_FeeWaiverOrReimbursementOverAssetsDateOfTerminationNovember 1, 2012
EXAMPLE:rr_ExpenseExampleAbstract 
Expense Example [Heading]rr_ExpenseExampleHeadingEXAMPLE:
Expense Example Narrative [Text Block]rr_ExpenseExampleNarrativeTextBlockThe following Example is based on expenses without waivers except for the waiver of the management fee paid by the subsidiary (which is included under Fee Waiver in the table above). 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 [Heading]rr_ExpenseExampleByYearHeadingThe 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:
Portfolio Turnover:jif277751_PortfolioTurnoverAltAbstract 
Portfolio Turnover [Heading]rr_PortfolioTurnoverHeadingPortfolio Turnover:
Portfolio Turnover [Text Block]rr_PortfolioTurnoverTextBlockThe 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.
Principal Investment Strategiesjif277751_PrincipalInvestmentStrategiesAbstract 
Strategy [Heading]rr_StrategyHeadingPRINCIPAL INVESTMENT STRATEGIES
Strategy Narrative [Text Block]rr_StrategyNarrativeTextBlock

Under normal market conditions, the Fund seeks to allocate its assets among the following inflation-related investment categories: global inflation-linked securities, commodity-linked investments, emerging market debt, emerging market equity, global real estate, and short-duration debt. Inflation-related investment categories are those which may provide what is known as “real return,” or a rate of return above the rate of inflation over a market cycle. The Fund has wide flexibility to allocate assets across categories and may, at times, allocate assets to less than all categories. The Fund’s Allocation Committee utilizes a “top down” analysis of macroeconomic factors to determine the overall allocation to each of the Fund’s investment categories. Individual portfolio managers generally utilize a “bottom up” approach in choosing investments where the portfolio managers look at companies one at a time to determine if an investment is an attractive investment opportunity and if it is consistent with the Fund’s investment policies, but may also consider macroeconomic factors. Due to the nature of the securities in which the Fund invests and the allocation process, it may have relatively high portfolio turnover compared to other funds.

The Fund’s investment in global inflation-linked securities will generally consist of inflation-indexed bonds issued by both governments and corporations, and may include non-U.S. issuers, including emerging markets. Such investments may include, but are not limited to, Treasury Inflation-Protected Securities, also known as TIPS. The Fund may utilize inflation index swaps to hedge against unexpected changes in the rate of inflation as measured by an inflation index such as the Consumer Price Index. The Fund may utilize reverse repurchase agreements to generate income as part of its inflation-related strategies. Proceeds from reverse repurchase transactions may be invested in other securities or instruments in an effort to increase the Fund’s investment returns.

To seek exposure to the commodities markets, the Fund may invest in 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 will seek to gain exposure to the commodity markets, in whole or in part, through investments 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 of the Fund. The Subsidiary invests in commodity-linked investments and other investments which may serve as margin or collateral for the Subsidiary’s derivative positions.

The Fund’s investments in emerging market debt securities and short-duration debt securities may include, but are not limited to, corporate bonds, government bonds, municipal bonds, convertible bonds, mortgage-backed securities, zero-coupon bonds, and agency securities. The Fund may invest in debt securities of issuers in a number of developed market countries, which may include the United States. The Fund may invest in debt securities with a range of maturities from short- to long-term. The Fund may invest up to 25% of its net assets in high-yield/high-risk debt securities.

The Fund’s investments in emerging market equity securities include securities of issuers that (i) are primarily listed on the trading market of an emerging market country; (ii) are incorporated or have their principal business activities in an emerging market country; or (iii) derive 50% or more of their revenues from, or have 50% or more of their assets in, an emerging market country. An emerging market country is any country that has been determined by an international organization, such as the World Bank, to have a low to middle income economy and/or any country that is not included in the Morgan Stanley Capital International World IndexSM, which measures the equity market performance of developed markets.

The Fund may invest in equity and debt securities of U.S. and non-U.S. 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, real estate investment trusts (“REITs”), and similar REIT-like entities such as foreign entities that have REIT characteristics.

In addition to the allocations above, the Fund may invest in other inflation-related investment categories, which may include investments in money market instruments, buy backs or dollar rolls, other securitized debt products, preferred stock, bank loans, private placements, exchange-traded notes, and other investment companies, including exchange-traded funds (“ETFs”), and commodity-related ETFs. The Fund may invest in companies of any market capitalization. The Fund’s investments may be denominated in local currency or U.S. dollar-denominated. The Fund may lend portfolio securities on a short-term or long-term basis, in an amount to up to 1/3 of its assets as determined at the time of the loan origination.

In addition to commodities-linked derivative instruments and inflation index swaps, the Fund may also invest its assets in derivative instruments that have a value derived from other underlying assets, such as stocks, bonds, currencies, interest rates or market indices. The Fund may invest in swaps to gain access to foreign markets, including circumstances where direct investment may be restricted or unavailable. The Fund may also invest in derivative instruments, such as forward currency contracts, to hedge the value of the Fund’s portfolio against the Fund’s benchmark index. The Fund may also invest in derivative instruments (by taking long and/or short positions) for other purposes, including hedging, 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, 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. For more information on the Fund’s use of derivatives, refer to the Fund’s shareholder reports and Form N-Q reports, which are filed with the Securities and Exchange Commission.

Principal Investment Risksjif277751_PrincipalInvestmentRisksAbstract 
Risk [Heading]rr_RiskHeadingPRINCIPAL 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 asset allocation portfolio, which includes common stocks, commodity-linked investments, emerging market securities, and derivatives. Such investments tend to be more volatile than many other investment choices.

Management Risk. The Fund’s ability to achieve its investment objective depends largely upon successful evaluation of the risk, potential returns, and correlation among the various investment categories in which the Fund may invest, such as inflation-linked securities, commodity-related investments, emerging market debt, emerging market equity, global real estate, and short-duration debt. You could lose money on your investment in the Fund as a result of these allocations. Additionally, Armored Wolf has a limited history of operations. 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 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.

Inflation-Linked Securities Risk. Because of their inflation adjustment feature, inflation-linked bonds typically have lower yields than conventional fixed-rate bonds. In addition, inflation-linked bonds also normally decline in price when real interest rates rise. In the event of deflation, in which prices decline over time, the principal and income of inflation-linked bonds would likely decline, resulting in losses to the Fund. Inflation-linked securities such as inflation index swaps are also subject to inflation risk, where such 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.

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.

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 Fund has applied for a private letter ruling from the Internal Revenue Service (“IRS”) with respect to the tax treatment of income from its investment in the Subsidiary. 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, 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.

Leverage Risk. Gains or losses from a derivative can be substantially greater than the derivative’s original cost, and can therefore involve leverage. In particular, certain commodity-linked derivatives or commodity-related ETFs may subject the Fund to leveraged market exposure to commodities. Leverage also occurs when the Fund increases its assets available for investment through borrowings or similar transactions. The Fund’s use of leverage can magnify the effect of any gains or losses, causing the Fund to be more volatile than if it had not been leveraged. There is no assurance that any leveraging strategy will be successful.

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.

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. Such leveraging transactions make the value of an investment in the Fund more volatile and increases 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.

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 can be substantially greater than the derivative’s original cost, and can therefore involve 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.

Foreign Exposure Risk. The Fund normally has significant exposure to foreign markets, including 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. 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.

Emerging Markets Risk. The risks of foreign investing mentioned above are heightened when investing in emerging markets. Emerging markets securities are exposed to 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, 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. As of June 30, 2011, approximately 6.8% of the Fund’s investments were in emerging markets.

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 their value 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.

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.

Mortgage-Backed Securities Risk. Mortgage-backed securities tend to be more sensitive to changes in interest rates than other types of 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.

Real Estate Risk. An investment in the Fund may be subject to many of the same risks as a direct investment in real estate. The value of securities of issuers in the real estate and real estate-related industries, including REITs, 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 issuer. These factors may impact the Fund’s investments in foreign real estate markets differently than U.S. real estate markets.

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.

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 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 index 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 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.

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.

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 return. 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.

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_RiskLoseMoneyThe biggest risk is that the Fund’s returns will vary, and you could lose money.
Risk Nondiversified Status [Text]rr_RiskNondiversifiedStatusNondiversification 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_RiskNotInsuredDepositoryInstitutionAn 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 INFORMATIONjif277751_FundPastPerformanceAbstract 
Bar Chart and Performance Table [Heading]rr_BarChartAndPerformanceTableHeadingPERFORMANCE INFORMATION
Performance Narrative [Text Block]rr_PerformanceNarrativeTextBlockThe Fund does not have a full calendar year of operations. Performance information for certain periods will be included in the Fund’s first annual and/or semiannual report.
Performance One Year or Less [Text]rr_PerformanceOneYearOrLessThe Fund does not have a full calendar year of operations.
Janus Real Return Allocation Fund | Class D Shares | Class D
 
ANNUAL FUND OPERATING EXPENSESrr_OperatingExpensesAbstract 
Operating Expenses Column [Text]rr_OperatingExpensesColumnNameClass D
Management Feesrr_ManagementFeesOverAssets0.75%[11]
Other Expensesrr_OtherExpensesOverAssets1.23%[12]
Other Expenses of the Fundrr_Component1OtherExpensesOverAssets1.11%
Other Expenses of the Subsidiaryrr_Component2OtherExpensesOverAssets0.12%
Total Annual Fund Operating Expensesrr_ExpensesOverAssets1.98%[14]
Fee Waiverrr_FeeWaiverOrReimbursementOverAssets0.83%[14]
Net Annual Fund Operating Expenses After Fee Waiverrr_NetExpensesOverAssets1.15%[14]
EXAMPLE:rr_ExpenseExampleAbstract 
Expense Example, By Year, Column [Text]rr_ExpenseExampleByYearColumnNameClass D Shares
1 Yearrr_ExpenseExampleYear01201
3 Yearsrr_ExpenseExampleYear03621
Janus Flexible Bond Fund | Class A, C, S, I, R, T Shares
 
Risk/Return:rr_RiskReturnAbstract 
Risk/Return [Heading]rr_RiskReturnHeadingFUND SUMMARY Janus Flexible Bond Fund
Objective [Heading]rr_ObjectiveHeadingINVESTMENT OBJECTIVE
Objective, Primary [Text Block]rr_ObjectivePrimaryTextBlockJanus Flexible Bond Fund seeks to obtain maximum total return, consistent with preservation of capital.
FEES AND EXPENSES OF THE FUNDjif277751_FundFeesAndExpensesAbstract 
Expense [Heading]rr_ExpenseHeadingFEES AND EXPENSES OF THE FUND
Expense Narrative [Text Block]rr_ExpenseNarrativeTextBlockThis 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.
Expense Breakpoint Discountsjif277751_ExpenseBreakpointDiscountsAbstract 
Expense Breakpoint Discounts [Text]rr_ExpenseBreakpointDiscountsFor 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 44 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_ExpenseBreakpointMinimumInvestmentRequiredAmount50,000
SHAREHOLDER FEESrr_ShareholderFeesAbstract 
Shareholder Fees Caption [Text]rr_ShareholderFeesCaptionSHAREHOLDER FEES (fees paid directly from your investment)
ANNUAL FUND OPERATING EXPENSESrr_OperatingExpensesAbstract 
Operating Expenses Caption [Text]rr_OperatingExpensesCaptionANNUAL 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 Terminationrr_FeeWaiverOrReimbursementOverAssetsDateOfTerminationNovember 1, 2012
EXAMPLE:rr_ExpenseExampleAbstract 
Expense Example [Heading]rr_ExpenseExampleHeadingEXAMPLE:
Expense Example Narrative [Text Block]rr_ExpenseExampleNarrativeTextBlockThe 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 [Heading]rr_ExpenseExampleByYearHeadingThe 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 by, Year, Caption [Text]rr_ExpenseExampleByYearCaptionIf Shares are redeemed:
Expense Example, No Redemption:rr_ExpenseExampleNoRedemptionAbstract 
Expense Example, No Redemption, By Year, Caption [Text]rr_ExpenseExampleNoRedemptionByYearCaptionIf Shares are not redeemed:
Portfolio Turnover:jif277751_PortfolioTurnoverAltAbstract 
Portfolio Turnover [Heading]rr_PortfolioTurnoverHeadingPortfolio Turnover:
Portfolio Turnover [Text Block]rr_PortfolioTurnoverTextBlockThe 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 period, the Fund’s portfolio turnover rate was 147% of the average value of its portfolio.
Portfolio Turnover, Raterr_PortfolioTurnoverRate147.00%
Principal Investment Strategiesjif277751_PrincipalInvestmentStrategiesAbstract 
Strategy [Heading]rr_StrategyHeadingPRINCIPAL 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 bonds, corporate bonds, convertible bonds, mortgage-backed securities, and zero-coupon bonds. The Fund will invest at least 65% 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 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. 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 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 also invest in foreign debt securities, which may include investments in emerging markets.

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 Risksjif277751_PrincipalInvestmentRisksAbstract 
Risk [Heading]rr_RiskHeadingPRINCIPAL 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 their value 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.

Mortgage-Backed Securities Risk. Mortgage-backed securities tend to be more sensitive to changes in interest rates than other types of 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.

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.

Foreign Exposure Risk. The Fund may have exposure to foreign markets, including 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. 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.

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_RiskLoseMoneyAlthough 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_RiskNotInsuredDepositoryInstitutionAn 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 INFORMATIONjif277751_FundPastPerformanceAbstract 
Bar Chart and Performance Table [Heading]rr_BarChartAndPerformanceTableHeadingPERFORMANCE 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.

• 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, without the effect of any 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, 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 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.

Bar Chart Does Not Reflect Sales Loads [Text]rr_BarChartDoesNotReflectSalesLoadsThe 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.
Performance Additional Market Index [Text]rr_PerformanceAdditionalMarketIndexThe 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 Past Does Not Indicate Future [Text]rr_PerformancePastDoesNotIndicateFutureThe Fund’s past performance (before and after taxes) does not necessarily indicate how it will perform in the future.
Performance Table Closing [Text Block]rr_PerformanceTableClosingTextBlockUpdated performance information is available at janus.com/advisor/mutual-funds or by calling 1-877-335-2687.
Performance Availability Website Address [Text]rr_PerformanceAvailabilityWebSiteAddressjanus.com/advisor/mutual-funds
Performance Availability Phone [Text]rr_PerformanceAvailabilityPhone1-877-335-2687
Annual Total Returnsrr_BarChartTableAbstract 
Bar Chart [Heading]rr_BarChartHeadingAnnual Total Returns for Class T 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, Labelrr_YearToDateReturnLabelThe Fund’s year-to-date return as of the calendar quarter ended September 30, 2011 was 5.10%.
Bar Chart, Year to Date Return, Daterr_BarChartYearToDateReturnDateSep. 30, 2011
Bar Chart, Year to Date Returnrr_BarChartYearToDateReturn5.10%
Average Annual Total Returnsrr_AverageAnnualReturnAbstract 
Captionrr_AverageAnnualReturnCaptionAverage Annual Total Returns (periods ended 12/31/10)
Performance Table Narrativerr_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 Uses Highest Federal Raterr_PerformanceTableUsesHighestFederalRateAfter-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 Deferredrr_PerformanceTableNotRelevantToTaxDeferredActual 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_PerformanceTableOneClassOfAfterTaxShownAfter-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.
Janus Flexible Bond Fund | Class A, C, S, I, R, T Shares | Class A
 
SHAREHOLDER FEESrr_ShareholderFeesAbstract 
Shareholder Fees Column [Text]rr_ShareholderFeesColumnNameClass A
Maximum Sales Charge (load) Imposed on Purchases (as a percentage of offering price)rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice4.75%
Maximum Deferred Sales Charge (load) (as a percentage of the lower of original purchase price or redemption proceeds)rr_MaximumDeferredSalesChargeOverOther none
ANNUAL FUND OPERATING EXPENSESrr_OperatingExpensesAbstract 
Operating Expenses Column [Text]rr_OperatingExpensesColumnNameClass A
Management Feesrr_ManagementFeesOverAssets0.41%
Distribution/Service (12b-1) Feesrr_DistributionAndService12b1FeesOverAssets0.25%
Other Expensesrr_OtherExpensesOverAssets0.11%
Total Annual Fund Operating Expensesrr_ExpensesOverAssets0.77%[15]
Fee Waiverrr_FeeWaiverOrReimbursementOverAssets none [15]
Net Annual Fund Operating Expenses After Fee Waiverrr_NetExpensesOverAssets0.77%[15]
EXAMPLE:rr_ExpenseExampleAbstract 
Expense Example, By Year, Column [Text]rr_ExpenseExampleByYearColumnNameClass A Shares
1 Yearrr_ExpenseExampleYear01550
3 Yearsrr_ExpenseExampleYear03709
5 Yearsrr_ExpenseExampleYear05883
10 Yearsrr_ExpenseExampleYear101,384
Expense Example, No Redemption:rr_ExpenseExampleNoRedemptionAbstract 
Expense Example, No Redemption, By Year, Column [Text]rr_ExpenseExampleNoRedemptionByYearColumnNameClass A Shares
1 Yearrr_ExpenseExampleNoRedemptionYear01550
3 Yearsrr_ExpenseExampleNoRedemptionYear03709
5 Yearsrr_ExpenseExampleNoRedemptionYear05883
10 Yearsrr_ExpenseExampleNoRedemptionYear101,384
Janus Flexible Bond Fund | Class A, C, S, I, R, T Shares | Class C
 
SHAREHOLDER FEESrr_ShareholderFeesAbstract 
Shareholder Fees Column [Text]rr_ShareholderFeesColumnNameClass 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_MaximumDeferredSalesChargeOverOther1.00%
ANNUAL FUND OPERATING EXPENSESrr_OperatingExpensesAbstract 
Operating Expenses Column [Text]rr_OperatingExpensesColumnNameClass C
Management Feesrr_ManagementFeesOverAssets0.41%
Distribution/Service (12b-1) Feesrr_DistributionAndService12b1FeesOverAssets1.00%
Other Expensesrr_OtherExpensesOverAssets0.11%
Total Annual Fund Operating Expensesrr_ExpensesOverAssets1.52%[15]
Fee Waiverrr_FeeWaiverOrReimbursementOverAssets none [15]
Net Annual Fund Operating Expenses After Fee Waiverrr_NetExpensesOverAssets1.52%[15]
EXAMPLE:rr_ExpenseExampleAbstract 
Expense Example, By Year, Column [Text]rr_ExpenseExampleByYearColumnNameClass C Shares
1 Yearrr_ExpenseExampleYear01255
3 Yearsrr_ExpenseExampleYear03480
5 Yearsrr_ExpenseExampleYear05829
10 Yearsrr_ExpenseExampleYear101,813
Expense Example, No Redemption:rr_ExpenseExampleNoRedemptionAbstract 
Expense Example, No Redemption, By Year, Column [Text]rr_ExpenseExampleNoRedemptionByYearColumnNameClass C Shares
1 Yearrr_ExpenseExampleNoRedemptionYear01155
3 Yearsrr_ExpenseExampleNoRedemptionYear03480
5 Yearsrr_ExpenseExampleNoRedemptionYear05829
10 Yearsrr_ExpenseExampleNoRedemptionYear101,813
Janus Flexible Bond Fund | Class A, C, S, I, R, T Shares | Class S
 
SHAREHOLDER FEESrr_ShareholderFeesAbstract 
Shareholder Fees Column [Text]rr_ShareholderFeesColumnNameClass 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
ANNUAL FUND OPERATING EXPENSESrr_OperatingExpensesAbstract 
Operating Expenses Column [Text]rr_OperatingExpensesColumnNameClass S
Management Feesrr_ManagementFeesOverAssets0.41%
Distribution/Service (12b-1) Feesrr_DistributionAndService12b1FeesOverAssets0.25%
Other Expensesrr_OtherExpensesOverAssets0.30%
Total Annual Fund Operating Expensesrr_ExpensesOverAssets0.96%[15]
Fee Waiverrr_FeeWaiverOrReimbursementOverAssets none [15]
Net Annual Fund Operating Expenses After Fee Waiverrr_NetExpensesOverAssets0.96%[15]
EXAMPLE:rr_ExpenseExampleAbstract 
Expense Example, By Year, Column [Text]rr_ExpenseExampleByYearColumnNameClass S Shares
1 Yearrr_ExpenseExampleYear0198
3 Yearsrr_ExpenseExampleYear03306
5 Yearsrr_ExpenseExampleYear05531
10 Yearsrr_ExpenseExampleYear101,178
Expense Example, No Redemption:rr_ExpenseExampleNoRedemptionAbstract 
Expense Example, No Redemption, By Year, Column [Text]rr_ExpenseExampleNoRedemptionByYearColumnNameClass S Shares
1 Yearrr_ExpenseExampleNoRedemptionYear0198
3 Yearsrr_ExpenseExampleNoRedemptionYear03306
5 Yearsrr_ExpenseExampleNoRedemptionYear05531
10 Yearsrr_ExpenseExampleNoRedemptionYear101,178
Janus Flexible Bond Fund | Class A, C, S, I, R, T Shares | Class I
 
SHAREHOLDER FEESrr_ShareholderFeesAbstract 
Shareholder Fees Column [Text]rr_ShareholderFeesColumnNameClass 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
ANNUAL FUND OPERATING EXPENSESrr_OperatingExpensesAbstract 
Operating Expenses Column [Text]rr_OperatingExpensesColumnNameClass I
Management Feesrr_ManagementFeesOverAssets0.41%
Distribution/Service (12b-1) Feesrr_DistributionAndService12b1FeesOverAssets none
Other Expensesrr_OtherExpensesOverAssets0.18%
Total Annual Fund Operating Expensesrr_ExpensesOverAssets0.59%[15]
Fee Waiverrr_FeeWaiverOrReimbursementOverAssets0.03%[15]
Net Annual Fund Operating Expenses After Fee Waiverrr_NetExpensesOverAssets0.56%[15]
EXAMPLE:rr_ExpenseExampleAbstract 
Expense Example, By Year, Column [Text]rr_ExpenseExampleByYearColumnNameClass I Shares
1 Yearrr_ExpenseExampleYear0160
3 Yearsrr_ExpenseExampleYear03189
5 Yearsrr_ExpenseExampleYear05329
10 Yearsrr_ExpenseExampleYear10738
Expense Example, No Redemption:rr_ExpenseExampleNoRedemptionAbstract 
Expense Example, No Redemption, By Year, Column [Text]rr_ExpenseExampleNoRedemptionByYearColumnNameClass I Shares
1 Yearrr_ExpenseExampleNoRedemptionYear0160
3 Yearsrr_ExpenseExampleNoRedemptionYear03189
5 Yearsrr_ExpenseExampleNoRedemptionYear05329
10 Yearsrr_ExpenseExampleNoRedemptionYear10738
Janus Flexible Bond Fund | Class A, C, S, I, R, T Shares | Class R
 
SHAREHOLDER FEESrr_ShareholderFeesAbstract 
Shareholder Fees Column [Text]rr_ShareholderFeesColumnNameClass 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
ANNUAL FUND OPERATING EXPENSESrr_OperatingExpensesAbstract 
Operating Expenses Column [Text]rr_OperatingExpensesColumnNameClass R
Management Feesrr_ManagementFeesOverAssets0.41%
Distribution/Service (12b-1) Feesrr_DistributionAndService12b1FeesOverAssets0.50%
Other Expensesrr_OtherExpensesOverAssets0.30%
Total Annual Fund Operating Expensesrr_ExpensesOverAssets1.21%[15]
Fee Waiverrr_FeeWaiverOrReimbursementOverAssets none [15]
Net Annual Fund Operating Expenses After Fee Waiverrr_NetExpensesOverAssets1.21%[15]
EXAMPLE:rr_ExpenseExampleAbstract 
Expense Example, By Year, Column [Text]rr_ExpenseExampleByYearColumnNameClass R Shares
1 Yearrr_ExpenseExampleYear01123
3 Yearsrr_ExpenseExampleYear03384
5 Yearsrr_ExpenseExampleYear05665
10 Yearsrr_ExpenseExampleYear101,466
Expense Example, No Redemption:rr_ExpenseExampleNoRedemptionAbstract 
Expense Example, No Redemption, By Year, Column [Text]rr_ExpenseExampleNoRedemptionByYearColumnNameClass R Shares
1 Yearrr_ExpenseExampleNoRedemptionYear01123
3 Yearsrr_ExpenseExampleNoRedemptionYear03384
5 Yearsrr_ExpenseExampleNoRedemptionYear05665
10 Yearsrr_ExpenseExampleNoRedemptionYear101,466
Janus Flexible Bond Fund | Class A, C, S, I, R, T Shares | Class T
 
SHAREHOLDER FEESrr_ShareholderFeesAbstract 
Shareholder Fees Column [Text]rr_ShareholderFeesColumnNameClass 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
ANNUAL FUND OPERATING EXPENSESrr_OperatingExpensesAbstract 
Operating Expenses Column [Text]rr_OperatingExpensesColumnNameClass T
Management Feesrr_ManagementFeesOverAssets0.41%
Distribution/Service (12b-1) Feesrr_DistributionAndService12b1FeesOverAssets none
Other Expensesrr_OtherExpensesOverAssets0.30%
Total Annual Fund Operating Expensesrr_ExpensesOverAssets0.71%[15]
Fee Waiverrr_FeeWaiverOrReimbursementOverAssets none [15]
Net Annual Fund Operating Expenses After Fee Waiverrr_NetExpensesOverAssets0.71%[15]
EXAMPLE:rr_ExpenseExampleAbstract 
Expense Example, By Year, Column [Text]rr_ExpenseExampleByYearColumnNameClass T Shares
1 Yearrr_ExpenseExampleYear0173
3 Yearsrr_ExpenseExampleYear03227
5 Yearsrr_ExpenseExampleYear05395
10 Yearsrr_ExpenseExampleYear10883
Expense Example, No Redemption:rr_ExpenseExampleNoRedemptionAbstract 
Expense Example, No Redemption, By Year, Column [Text]rr_ExpenseExampleNoRedemptionByYearColumnNameClass T Shares
1 Yearrr_ExpenseExampleNoRedemptionYear0173
3 Yearsrr_ExpenseExampleNoRedemptionYear03227
5 Yearsrr_ExpenseExampleNoRedemptionYear05395
10 Yearsrr_ExpenseExampleNoRedemptionYear10883
Annual Total Returnsrr_BarChartTableAbstract 
2001rr_AnnualReturn20017.23%
2002rr_AnnualReturn20029.93%
2003rr_AnnualReturn20036.37%
2004rr_AnnualReturn20043.82%
2005rr_AnnualReturn20051.79%
2006rr_AnnualReturn20064.12%
2007rr_AnnualReturn20076.87%
2008rr_AnnualReturn20085.64%
2009rr_AnnualReturn200912.54%
2010rr_AnnualReturn20107.45%
Highest Quarterly Return, Labelrr_HighestQuarterlyReturnLabelBest Quarter:
Highest Quarterly Return, Daterr_BarChartHighestQuarterlyReturnDateSep. 30, 2009
Highest Quarterly Returnrr_BarChartHighestQuarterlyReturn5.58%
Lowest Quarterly Return, Labelrr_LowestQuarterlyReturnLabelWorst Quarter:
Lowest Quarterly Return, Daterr_BarChartLowestQuarterlyReturnDateJun. 30, 2004
Lowest Quarterly Returnrr_BarChartLowestQuarterlyReturn(2.99%)
Janus Flexible Bond Fund | Class A, C, S, I, R, T Shares | Return Before Taxes | Class A
 
Average Annual Total Returnsrr_AverageAnnualReturnAbstract 
Columnrr_AverageAnnualReturnColumnNameClass A Shares
Labelrr_AverageAnnualReturnLabelReturn Before Taxes[3]
1 Yearrr_AverageAnnualReturnYear012.26%
5 Yearsrr_AverageAnnualReturnYear056.21%
10 Yearsrr_AverageAnnualReturnYear105.99%
Since Inceptionrr_AverageAnnualReturnSinceInception7.35%
Inception Daterr_AverageAnnualReturnInceptionDateJul. 07, 1987
Janus Flexible Bond Fund | Class A, C, S, I, R, T Shares | Return Before Taxes | Class C
 
Average Annual Total Returnsrr_AverageAnnualReturnAbstract 
Columnrr_AverageAnnualReturnColumnNameClass C Shares
Labelrr_AverageAnnualReturnLabelReturn Before Taxes[4]
1 Yearrr_AverageAnnualReturnYear015.57%
5 Yearsrr_AverageAnnualReturnYear056.53%
10 Yearsrr_AverageAnnualReturnYear105.78%
Since Inceptionrr_AverageAnnualReturnSinceInception6.90%
Inception Daterr_AverageAnnualReturnInceptionDateJul. 07, 1987
Janus Flexible Bond Fund | Class A, C, S, I, R, T Shares | Return Before Taxes | Class S
 
Average Annual Total Returnsrr_AverageAnnualReturnAbstract 
Columnrr_AverageAnnualReturnColumnNameClass S Shares
Labelrr_AverageAnnualReturnLabelReturn Before Taxes
1 Yearrr_AverageAnnualReturnYear017.27%
5 Yearsrr_AverageAnnualReturnYear057.07%
10 Yearsrr_AverageAnnualReturnYear106.31%
Since Inceptionrr_AverageAnnualReturnSinceInception7.43%
Inception Daterr_AverageAnnualReturnInceptionDateJul. 07, 1987
Janus Flexible Bond Fund | Class A, C, S, I, R, T Shares | Return Before Taxes | Class I
 
Average Annual Total Returnsrr_AverageAnnualReturnAbstract 
Columnrr_AverageAnnualReturnColumnNameClass I Shares
Labelrr_AverageAnnualReturnLabelReturn Before Taxes
1 Yearrr_AverageAnnualReturnYear017.59%
5 Yearsrr_AverageAnnualReturnYear057.29%
10 Yearsrr_AverageAnnualReturnYear106.54%
Since Inceptionrr_AverageAnnualReturnSinceInception7.58%
Inception Daterr_AverageAnnualReturnInceptionDateJul. 07, 1987
Janus Flexible Bond Fund | Class A, C, S, I, R, T Shares | Return Before Taxes | Class R
 
Average Annual Total Returnsrr_AverageAnnualReturnAbstract 
Columnrr_AverageAnnualReturnColumnNameClass R Shares
Labelrr_AverageAnnualReturnLabelReturn Before Taxes
1 Yearrr_AverageAnnualReturnYear016.91%
5 Yearsrr_AverageAnnualReturnYear056.80%
10 Yearsrr_AverageAnnualReturnYear106.05%
Since Inceptionrr_AverageAnnualReturnSinceInception7.17%
Inception Daterr_AverageAnnualReturnInceptionDateJul. 07, 1987
Janus Flexible Bond Fund | Class A, C, S, I, R, T Shares | Return Before Taxes | Class T
 
Average Annual Total Returnsrr_AverageAnnualReturnAbstract 
Columnrr_AverageAnnualReturnColumnNameClass T Shares
Labelrr_AverageAnnualReturnLabelReturn Before Taxes
1 Yearrr_AverageAnnualReturnYear017.45%
5 Yearsrr_AverageAnnualReturnYear057.29%
10 Yearsrr_AverageAnnualReturnYear106.54%
Since Inceptionrr_AverageAnnualReturnSinceInception7.58%
Inception Daterr_AverageAnnualReturnInceptionDateJul. 07, 1987
Janus Flexible Bond Fund | Class A, C, S, I, R, T Shares | Return After Taxes on Distributions | Class T
 
Average Annual Total Returnsrr_AverageAnnualReturnAbstract 
Columnrr_AverageAnnualReturnColumnNameClass T Shares
Labelrr_AverageAnnualReturnLabelReturn After Taxes on Distributions
1 Yearrr_AverageAnnualReturnYear015.03%
5 Yearsrr_AverageAnnualReturnYear055.42%
10 Yearsrr_AverageAnnualReturnYear104.65%
Since Inceptionrr_AverageAnnualReturnSinceInception4.92%
Inception Daterr_AverageAnnualReturnInceptionDateJul. 07, 1987
Janus Flexible Bond Fund | Class A, C, S, I, R, T Shares | Return After Taxes on Distributions and Sale of Fund Shares | Class T
 
Average Annual Total Returnsrr_AverageAnnualReturnAbstract 
Columnrr_AverageAnnualReturnColumnNameClass T Shares
Labelrr_AverageAnnualReturnLabelReturn After Taxes on Distributions and Sale of Fund Shares[5]
1 Yearrr_AverageAnnualReturnYear014.98%
5 Yearsrr_AverageAnnualReturnYear055.15%
10 Yearsrr_AverageAnnualReturnYear104.49%
Since Inceptionrr_AverageAnnualReturnSinceInception4.88%
Inception Daterr_AverageAnnualReturnInceptionDateJul. 07, 1987
Janus Flexible Bond Fund | Class A, C, S, I, R, T Shares | Barclays Capital U.S. Aggregate Bond Index
 
Average Annual Total Returnsrr_AverageAnnualReturnAbstract 
Labelrr_AverageAnnualReturnLabelBarclays Capital U.S. Aggregate Bond Index
Index No Deduction for Fees, Expenses, Taxes [Text]rr_IndexNoDeductionForFeesExpensesTaxes(reflects no deduction for expenses, fees, or taxes)
1 Yearrr_AverageAnnualReturnYear016.54%
5 Yearsrr_AverageAnnualReturnYear055.80%
10 Yearsrr_AverageAnnualReturnYear105.84%
Since Inceptionrr_AverageAnnualReturnSinceInception7.31%
Inception Daterr_AverageAnnualReturnInceptionDateJul. 07, 1987
Janus Flexible Bond Fund | Class D Shares
 
Risk/Return:rr_RiskReturnAbstract 
Risk/Return [Heading]rr_RiskReturnHeadingFUND SUMMARY Janus Flexible Bond Fund
Objective [Heading]rr_ObjectiveHeadingINVESTMENT OBJECTIVE
Objective, Primary [Text Block]rr_ObjectivePrimaryTextBlockJanus Flexible Bond Fund seeks to obtain maximum total return, consistent with preservation of capital.
FEES AND EXPENSES OF THE FUNDjif277751_FundFeesAndExpensesAbstract 
Expense [Heading]rr_ExpenseHeadingFEES AND EXPENSES OF THE FUND
Expense Narrative [Text Block]rr_ExpenseNarrativeTextBlockThis table describes the fees and expenses that you may pay if you buy and hold Shares of the Fund.
ANNUAL FUND OPERATING EXPENSESrr_OperatingExpensesAbstract 
Operating Expenses Caption [Text]rr_OperatingExpensesCaptionANNUAL 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 Terminationrr_FeeWaiverOrReimbursementOverAssetsDateOfTerminationNovember 1, 2012
EXAMPLE:rr_ExpenseExampleAbstract 
Expense Example [Heading]rr_ExpenseExampleHeadingEXAMPLE:
Expense Example Narrative [Text Block]rr_ExpenseExampleNarrativeTextBlockThe 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 [Heading]rr_ExpenseExampleByYearHeadingThe 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:
Portfolio Turnover:jif277751_PortfolioTurnoverAltAbstract 
Portfolio Turnover [Heading]rr_PortfolioTurnoverHeadingPortfolio Turnover:
Portfolio Turnover [Text Block]rr_PortfolioTurnoverTextBlockThe 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 period, the Fund’s portfolio turnover rate was 147% of the average value of its portfolio.
Portfolio Turnover, Raterr_PortfolioTurnoverRate147.00%
Principal Investment Strategiesjif277751_PrincipalInvestmentStrategiesAbstract 
Strategy [Heading]rr_StrategyHeadingPRINCIPAL 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 bonds, corporate bonds, convertible bonds, mortgage-backed securities, and zero-coupon bonds. The Fund will invest at least 65% 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 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. 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 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 also invest in foreign debt securities, which may include investments in emerging markets.

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 Risksjif277751_PrincipalInvestmentRisksAbstract 
Risk [Heading]rr_RiskHeadingPRINCIPAL 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 their value 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.

Mortgage-Backed Securities Risk. Mortgage-backed securities tend to be more sensitive to changes in interest rates than other types of 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.

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.

Foreign Exposure Risk. The Fund may have exposure to foreign markets, including 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. 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.

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_RiskLoseMoneyAlthough 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_RiskNotInsuredDepositoryInstitutionAn 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 INFORMATIONjif277751_FundPastPerformanceAbstract 
Bar Chart and Performance Table [Heading]rr_BarChartAndPerformanceTableHeadingPERFORMANCE 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_PerformanceAdditionalMarketIndexThe 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 Past Does Not Indicate Future [Text]rr_PerformancePastDoesNotIndicateFutureThe Fund’s past performance (before and after taxes) does not necessarily indicate how it will perform in the future.
Performance Table Closing [Text Block]rr_PerformanceTableClosingTextBlockUpdated performance information is available at janus.com/allfunds or by calling 1-800-525-3713.
Performance Availability Website Address [Text]rr_PerformanceAvailabilityWebSiteAddressjanus.com/allfunds
Performance Availability Phone [Text]rr_PerformanceAvailabilityPhone1-800-525-3713
Annual Total Returnsrr_BarChartTableAbstract 
Bar Chart [Heading]rr_BarChartHeadingAnnual Total Returns for Class D Shares (calendar year-end)
Bar Chart Closing [Text Block]rr_BarChartClosingTextBlockBest Quarter: Third Quarter 2009 5.58%          Worst Quarter: Second Quarter 2004 -2.99%
Year to Date Return, Labelrr_YearToDateReturnLabelThe Fund’s year-to-date return as of the calendar quarter ended September 30, 2011 was 5.19%.
Bar Chart, Year to Date Return, Daterr_BarChartYearToDateReturnDateSep. 30, 2011
Bar Chart, Year to Date Returnrr_BarChartYearToDateReturn5.19%
Average Annual Total Returnsrr_AverageAnnualReturnAbstract 
Captionrr_AverageAnnualReturnCaptionAverage Annual Total Returns (periods ended 12/31/10)
Performance Table Narrativerr_PerformanceTableNarrativeTextBlockAfter-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 Uses Highest Federal Raterr_PerformanceTableUsesHighestFederalRateAfter-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 Deferredrr_PerformanceTableNotRelevantToTaxDeferredActual 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.
Janus Flexible Bond Fund | Class D Shares | Class D
 
ANNUAL FUND OPERATING EXPENSESrr_OperatingExpensesAbstract 
Operating Expenses Column [Text]rr_OperatingExpensesColumnNameClass D
Management Feesrr_ManagementFeesOverAssets0.41%
Other Expensesrr_OtherExpensesOverAssets0.19%
Total Annual Fund Operating Expensesrr_ExpensesOverAssets0.60%[16]
EXAMPLE:rr_ExpenseExampleAbstract 
Expense Example, By Year, Column [Text]rr_ExpenseExampleByYearColumnNameClass D Shares
1 Yearrr_ExpenseExampleYear0161
3 Yearsrr_ExpenseExampleYear03192
5 Yearsrr_ExpenseExampleYear05335
10 Yearsrr_ExpenseExampleYear10750
Annual Total Returnsrr_BarChartTableAbstract 
2001rr_AnnualReturn20017.23%
2002rr_AnnualReturn20029.93%
2003rr_AnnualReturn20036.37%
2004rr_AnnualReturn20043.82%
2005rr_AnnualReturn20051.79%
2006rr_AnnualReturn20064.12%
2007rr_AnnualReturn20076.87%
2008rr_AnnualReturn20085.64%
2009rr_AnnualReturn200912.54%
2010rr_AnnualReturn20107.53%
Highest Quarterly Return, Labelrr_HighestQuarterlyReturnLabelBest Quarter:
Highest Quarterly Return, Daterr_BarChartHighestQuarterlyReturnDateSep. 30, 2009
Highest Quarterly Returnrr_BarChartHighestQuarterlyReturn5.58%
Lowest Quarterly Return, Labelrr_LowestQuarterlyReturnLabelWorst Quarter:
Lowest Quarterly Return, Daterr_BarChartLowestQuarterlyReturnDateJun. 30, 2004
Lowest Quarterly Returnrr_BarChartLowestQuarterlyReturn(2.99%)
Janus Flexible Bond Fund | Class D Shares | Return Before Taxes | Class D
 
Average Annual Total Returnsrr_AverageAnnualReturnAbstract 
Columnrr_AverageAnnualReturnColumnNameClass D Shares
Labelrr_AverageAnnualReturnLabelReturn Before Taxes
1 Yearrr_AverageAnnualReturnYear017.53%
5 Yearsrr_AverageAnnualReturnYear057.30%
10 Yearsrr_AverageAnnualReturnYear106.54%
Since Inceptionrr_AverageAnnualReturnSinceInception7.59%
Inception Daterr_AverageAnnualReturnInceptionDateJul. 07, 1987
Janus Flexible Bond Fund | Class D Shares | Return After Taxes on Distributions | Class D
 
Average Annual Total Returnsrr_AverageAnnualReturnAbstract 
Columnrr_AverageAnnualReturnColumnNameClass D Shares
Labelrr_AverageAnnualReturnLabelReturn After Taxes on Distributions
1 Yearrr_AverageAnnualReturnYear015.09%
5 Yearsrr_AverageAnnualReturnYear055.43%
10 Yearsrr_AverageAnnualReturnYear104.66%
Since Inceptionrr_AverageAnnualReturnSinceInception4.93%
Inception Daterr_AverageAnnualReturnInceptionDateJul. 07, 1987
Janus Flexible Bond Fund | Class D Shares | Return After Taxes on Distributions and Sale of Fund Shares | Class D
 
Average Annual Total Returnsrr_AverageAnnualReturnAbstract 
Columnrr_AverageAnnualReturnColumnNameClass D Shares
Labelrr_AverageAnnualReturnLabelReturn After Taxes on Distributions and Sale of Fund Shares[5]
1 Yearrr_AverageAnnualReturnYear015.04%
5 Yearsrr_AverageAnnualReturnYear055.16%
10 Yearsrr_AverageAnnualReturnYear104.49%
Since Inceptionrr_AverageAnnualReturnSinceInception4.88%
Inception Daterr_AverageAnnualReturnInceptionDateJul. 07, 1987
Janus Flexible Bond Fund | Class D Shares | Barclays Capital U.S. Aggregate Bond Index
 
Average Annual Total Returnsrr_AverageAnnualReturnAbstract 
Labelrr_AverageAnnualReturnLabelBarclays Capital U.S. Aggregate Bond Index
Index No Deduction for Fees, Expenses, Taxes [Text]rr_IndexNoDeductionForFeesExpensesTaxes(reflects no deduction for expenses, fees, or taxes)
1 Yearrr_AverageAnnualReturnYear016.54%
5 Yearsrr_AverageAnnualReturnYear055.80%
10 Yearsrr_AverageAnnualReturnYear105.84%
Since Inceptionrr_AverageAnnualReturnSinceInception7.31%
Inception Daterr_AverageAnnualReturnInceptionDateJul. 07, 1987
Janus Global Bond Fund | Class A, C, S, I, T Shares
 
Risk/Return:rr_RiskReturnAbstract 
Risk/Return [Heading]rr_RiskReturnHeadingFUND SUMMARY Janus Global Bond Fund
Objective [Heading]rr_ObjectiveHeadingINVESTMENT OBJECTIVE
Objective, Primary [Text Block]rr_ObjectivePrimaryTextBlockJanus Global Bond Fund seeks total return, consistent with preservation of capital.
FEES AND EXPENSES OF THE FUNDjif277751_FundFeesAndExpensesAbstract 
Expense [Heading]rr_ExpenseHeadingFEES AND EXPENSES OF THE FUND
Expense Narrative [Text Block]rr_ExpenseNarrativeTextBlockThis 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.
Expense Breakpoint Discountsjif277751_ExpenseBreakpointDiscountsAbstract 
Expense Breakpoint Discounts [Text]rr_ExpenseBreakpointDiscountsFor 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 44 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_ExpenseBreakpointMinimumInvestmentRequiredAmount50,000
SHAREHOLDER FEESrr_ShareholderFeesAbstract 
Shareholder Fees Caption [Text]rr_ShareholderFeesCaptionSHAREHOLDER FEES (fees paid directly from your investment)
ANNUAL FUND OPERATING EXPENSESrr_OperatingExpensesAbstract 
Operating Expenses Caption [Text]rr_OperatingExpensesCaptionANNUAL 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 Terminationrr_FeeWaiverOrReimbursementOverAssetsDateOfTerminationNovember 1, 2012
EXAMPLE:rr_ExpenseExampleAbstract 
Expense Example [Heading]rr_ExpenseExampleHeadingEXAMPLE:
Expense Example Narrative [Text Block]rr_ExpenseExampleNarrativeTextBlockThe 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 [Heading]rr_ExpenseExampleByYearHeadingThe 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 by, Year, Caption [Text]rr_ExpenseExampleByYearCaptionIf Shares are redeemed:
Expense Example, No Redemption:rr_ExpenseExampleNoRedemptionAbstract 
Expense Example, No Redemption, By Year, Caption [Text]rr_ExpenseExampleNoRedemptionByYearCaptionIf Shares are not redeemed:
Portfolio Turnover:jif277751_PortfolioTurnoverAltAbstract 
Portfolio Turnover [Heading]rr_PortfolioTurnoverHeadingPortfolio Turnover:
Portfolio Turnover [Text Block]rr_PortfolioTurnoverTextBlockThe 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 period, the Fund’s portfolio turnover rate was 173% of the average value of its portfolio.
Portfolio Turnover, Raterr_PortfolioTurnoverRate173.00%
Principal Investment Strategiesjif277751_PrincipalInvestmentStrategiesAbstract 
Strategy [Heading]rr_StrategyHeadingPRINCIPAL 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 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 located in 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 floating rate loans, buy backs or dollar rolls, 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 an underlying asset, such as equity securities, bonds, commodities, currencies, interest rates, or market indices, as substitutes for securities in which the Fund invests. The Fund may use futures, options, and swaps (including interest rate swaps, total return swaps, and credit default swaps). The Fund may also invest in derivative instruments (by taking long and/or short positions) for other purposes, including hedging, 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. The Fund’s exposure to derivatives will vary, is not limited to those derivatives listed, and could be significant at times. For more information on the Fund’s use of derivatives, refer to the Fund’s shareholder reports and Form N-Q reports, which are filed with the Securities and Exchange Commission.

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 Risksjif277751_PrincipalInvestmentRisksAbstract 
Risk [Heading]rr_RiskHeadingPRINCIPAL 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 their value 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.

Mortgage-Backed Securities Risk. Mortgage-backed securities tend to be more sensitive to changes in interest rates than other types of 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.

Foreign Exposure Risk. The Fund normally has significant exposure to foreign markets, including 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. 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.

Emerging Markets Risk. The risks of foreign investing mentioned above are heightened when investing in emerging markets. Emerging markets securities are exposed to 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, 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 specialized risks. As of June 30, 2011, approximately 0.8% of the Fund’s investments were in emerging markets.

Sovereign Debt Risk. Investments in foreign government debt securities (“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.

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 common stocks, 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.

Floating Rate Loan Risk. There may be a number of intermediate participants in floating rate loan transactions and loan agreements have specific rights and obligations, and terms and conditions. Any number of factors in an investment in floating rate loans could cause the Fund to lose income or principal on a particular investment, which in turn could affect the Fund’s returns, and you could lose money. For the Fund’s secured or collateralized investments, lenders may have difficulty liquidating collateral, the collateral might decline in value or be insufficient, or the collateral might be set aside in a court proceeding such as a bankruptcy proceeding. There may be many claims by other lenders against the same collateral. The Fund could be held liable as a co-lender.

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 can be substantially greater than the derivative’s original cost, and can therefore involve 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_RiskLoseMoneyAlthough 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_RiskNotInsuredDepositoryInstitutionAn 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 INFORMATIONjif277751_FundPastPerformanceAbstract 
Bar Chart and Performance Table [Heading]rr_BarChartAndPerformanceTableHeadingPERFORMANCE INFORMATION
Performance Narrative [Text Block]rr_PerformanceNarrativeTextBlockThe Fund does not have a full calendar year of operations. Performance information for certain periods will be included in the Fund’s first annual and/or semiannual report.
Performance One Year or Less [Text]rr_PerformanceOneYearOrLessThe Fund does not have a full calendar year of operations.
Janus Global Bond Fund | Class A, C, S, I, T Shares | Class A
 
SHAREHOLDER FEESrr_ShareholderFeesAbstract 
Shareholder Fees Column [Text]rr_ShareholderFeesColumnNameClass A
Maximum Sales Charge (load) Imposed on Purchases (as a percentage of offering price)rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice4.75%
Maximum Deferred Sales Charge (load) (as a percentage of the lower of original purchase price or redemption proceeds)rr_MaximumDeferredSalesChargeOverOther none
ANNUAL FUND OPERATING EXPENSESrr_OperatingExpensesAbstract 
Operating Expenses Column [Text]rr_OperatingExpensesColumnNameClass A
Management Feesrr_ManagementFeesOverAssets0.60%
Distribution/Service (12b-1) Feesrr_DistributionAndService12b1FeesOverAssets0.25%
Other Expensesrr_OtherExpensesOverAssets2.66%
Total Annual Fund Operating Expensesrr_ExpensesOverAssets3.51%[17]
Fee Waiverrr_FeeWaiverOrReimbursementOverAssets2.49%[17]
Net Annual Fund Operating Expenses After Fee Waiverrr_NetExpensesOverAssets1.02%[17]
EXAMPLE:rr_ExpenseExampleAbstract 
Expense Example, By Year, Column [Text]rr_ExpenseExampleByYearColumnNameClass A Shares
1 Yearrr_ExpenseExampleYear01812
3 Yearsrr_ExpenseExampleYear031,501
5 Yearsrr_ExpenseExampleYear052,210
10 Yearsrr_ExpenseExampleYear104,078
Expense Example, No Redemption:rr_ExpenseExampleNoRedemptionAbstract 
Expense Example, No Redemption, By Year, Column [Text]rr_ExpenseExampleNoRedemptionByYearColumnNameClass A Shares
1 Yearrr_ExpenseExampleNoRedemptionYear01812
3 Yearsrr_ExpenseExampleNoRedemptionYear031,501
5 Yearsrr_ExpenseExampleNoRedemptionYear052,210
10 Yearsrr_ExpenseExampleNoRedemptionYear104,078
Janus Global Bond Fund | Class A, C, S, I, T Shares | Class C
 
SHAREHOLDER FEESrr_ShareholderFeesAbstract 
Shareholder Fees Column [Text]rr_ShareholderFeesColumnNameClass 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_MaximumDeferredSalesChargeOverOther1.00%
ANNUAL FUND OPERATING EXPENSESrr_OperatingExpensesAbstract 
Operating Expenses Column [Text]rr_OperatingExpensesColumnNameClass C
Management Feesrr_ManagementFeesOverAssets0.60%
Distribution/Service (12b-1) Feesrr_DistributionAndService12b1FeesOverAssets1.00%
Other Expensesrr_OtherExpensesOverAssets2.63%
Total Annual Fund Operating Expensesrr_ExpensesOverAssets4.23%[17]
Fee Waiverrr_FeeWaiverOrReimbursementOverAssets2.46%[17]
Net Annual Fund Operating Expenses After Fee Waiverrr_NetExpensesOverAssets1.77%[17]
EXAMPLE:rr_ExpenseExampleAbstract 
Expense Example, By Year, Column [Text]rr_ExpenseExampleByYearColumnNameClass C Shares
1 Yearrr_ExpenseExampleYear01525
3 Yearsrr_ExpenseExampleYear031,284
5 Yearsrr_ExpenseExampleYear052,156
10 Yearsrr_ExpenseExampleYear104,396
Expense Example, No Redemption:rr_ExpenseExampleNoRedemptionAbstract 
Expense Example, No Redemption, By Year, Column [Text]rr_ExpenseExampleNoRedemptionByYearColumnNameClass C Shares
1 Yearrr_ExpenseExampleNoRedemptionYear01425
3 Yearsrr_ExpenseExampleNoRedemptionYear031,284
5 Yearsrr_ExpenseExampleNoRedemptionYear052,156
10 Yearsrr_ExpenseExampleNoRedemptionYear104,396
Janus Global Bond Fund | Class A, C, S, I, T Shares | Class S
 
SHAREHOLDER FEESrr_ShareholderFeesAbstract 
Shareholder Fees Column [Text]rr_ShareholderFeesColumnNameClass 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
ANNUAL FUND OPERATING EXPENSESrr_OperatingExpensesAbstract 
Operating Expenses Column [Text]rr_OperatingExpensesColumnNameClass S
Management Feesrr_ManagementFeesOverAssets0.60%
Distribution/Service (12b-1) Feesrr_DistributionAndService12b1FeesOverAssets0.25%
Other Expensesrr_OtherExpensesOverAssets3.00%
Total Annual Fund Operating Expensesrr_ExpensesOverAssets3.85%[17]
Fee Waiverrr_FeeWaiverOrReimbursementOverAssets2.58%[17]
Net Annual Fund Operating Expenses After Fee Waiverrr_NetExpensesOverAssets1.27%[17]
EXAMPLE:rr_ExpenseExampleAbstract 
Expense Example, By Year, Column [Text]rr_ExpenseExampleByYearColumnNameClass S Shares
1 Yearrr_ExpenseExampleYear01387
3 Yearsrr_ExpenseExampleYear031,175
5 Yearsrr_ExpenseExampleYear051,981
10 Yearsrr_ExpenseExampleYear104,079
Expense Example, No Redemption:rr_ExpenseExampleNoRedemptionAbstract 
Expense Example, No Redemption, By Year, Column [Text]rr_ExpenseExampleNoRedemptionByYearColumnNameClass S Shares
1 Yearrr_ExpenseExampleNoRedemptionYear01387
3 Yearsrr_ExpenseExampleNoRedemptionYear031,175
5 Yearsrr_ExpenseExampleNoRedemptionYear051,981
10 Yearsrr_ExpenseExampleNoRedemptionYear104,079
Janus Global Bond Fund | Class A, C, S, I, T Shares | Class I
 
SHAREHOLDER FEESrr_ShareholderFeesAbstract 
Shareholder Fees Column [Text]rr_ShareholderFeesColumnNameClass 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
ANNUAL FUND OPERATING EXPENSESrr_OperatingExpensesAbstract 
Operating Expenses Column [Text]rr_OperatingExpensesColumnNameClass I
Management Feesrr_ManagementFeesOverAssets0.60%
Distribution/Service (12b-1) Feesrr_DistributionAndService12b1FeesOverAssets none
Other Expensesrr_OtherExpensesOverAssets2.54%
Total Annual Fund Operating Expensesrr_ExpensesOverAssets3.14%[17]
Fee Waiverrr_FeeWaiverOrReimbursementOverAssets2.37%[17]
Net Annual Fund Operating Expenses After Fee Waiverrr_NetExpensesOverAssets0.77%[17]
EXAMPLE:rr_ExpenseExampleAbstract 
Expense Example, By Year, Column [Text]rr_ExpenseExampleByYearColumnNameClass I Shares
1 Yearrr_ExpenseExampleYear01317
3 Yearsrr_ExpenseExampleYear03969
5 Yearsrr_ExpenseExampleYear051,645
10 Yearsrr_ExpenseExampleYear103,448
Expense Example, No Redemption:rr_ExpenseExampleNoRedemptionAbstract 
Expense Example, No Redemption, By Year, Column [Text]rr_ExpenseExampleNoRedemptionByYearColumnNameClass I Shares
1 Yearrr_ExpenseExampleNoRedemptionYear01317
3 Yearsrr_ExpenseExampleNoRedemptionYear03969
5 Yearsrr_ExpenseExampleNoRedemptionYear051,645
10 Yearsrr_ExpenseExampleNoRedemptionYear103,448
Janus Global Bond Fund | Class A, C, S, I, T Shares | Class T
 
SHAREHOLDER FEESrr_ShareholderFeesAbstract 
Shareholder Fees Column [Text]rr_ShareholderFeesColumnNameClass 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
ANNUAL FUND OPERATING EXPENSESrr_OperatingExpensesAbstract 
Operating Expenses Column [Text]rr_OperatingExpensesColumnNameClass T
Management Feesrr_ManagementFeesOverAssets0.60%
Distribution/Service (12b-1) Feesrr_DistributionAndService12b1FeesOverAssets none
Other Expensesrr_OtherExpensesOverAssets2.86%
Total Annual Fund Operating Expensesrr_ExpensesOverAssets3.46%[17]
Fee Waiverrr_FeeWaiverOrReimbursementOverAssets2.45%[17]
Net Annual Fund Operating Expenses After Fee Waiverrr_NetExpensesOverAssets1.01%[17]
EXAMPLE:rr_ExpenseExampleAbstract 
Expense Example, By Year, Column [Text]rr_ExpenseExampleByYearColumnNameClass T Shares
1 Yearrr_ExpenseExampleYear01349
3 Yearsrr_ExpenseExampleYear031,062
5 Yearsrr_ExpenseExampleYear051,798
10 Yearsrr_ExpenseExampleYear103,738
Expense Example, No Redemption:rr_ExpenseExampleNoRedemptionAbstract 
Expense Example, No Redemption, By Year, Column [Text]rr_ExpenseExampleNoRedemptionByYearColumnNameClass T Shares
1 Yearrr_ExpenseExampleNoRedemptionYear01349
3 Yearsrr_ExpenseExampleNoRedemptionYear031,062
5 Yearsrr_ExpenseExampleNoRedemptionYear051,798
10 Yearsrr_ExpenseExampleNoRedemptionYear103,738
Janus Global Bond Fund | Class D Shares
 
Risk/Return:rr_RiskReturnAbstract 
Risk/Return [Heading]rr_RiskReturnHeadingFUND SUMMARY Janus Global Bond Fund
Objective [Heading]rr_ObjectiveHeadingINVESTMENT OBJECTIVE
Objective, Primary [Text Block]rr_ObjectivePrimaryTextBlockJanus Global Bond Fund seeks total return, consistent with preservation of capital.
FEES AND EXPENSES OF THE FUNDjif277751_FundFeesAndExpensesAbstract 
Expense [Heading]rr_ExpenseHeadingFEES AND EXPENSES OF THE FUND
Expense Narrative [Text Block]rr_ExpenseNarrativeTextBlockThis table describes the fees and expenses that you may pay if you buy and hold Shares of the Fund.
ANNUAL FUND OPERATING EXPENSESrr_OperatingExpensesAbstract 
Operating Expenses Caption [Text]rr_OperatingExpensesCaptionANNUAL 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 Terminationrr_FeeWaiverOrReimbursementOverAssetsDateOfTerminationNovember 1, 2012
EXAMPLE:rr_ExpenseExampleAbstract 
Expense Example [Heading]rr_ExpenseExampleHeadingEXAMPLE:
Expense Example Narrative [Text Block]rr_ExpenseExampleNarrativeTextBlockThe 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 [Heading]rr_ExpenseExampleByYearHeadingThe 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:
Portfolio Turnover:jif277751_PortfolioTurnoverAltAbstract 
Portfolio Turnover [Heading]rr_PortfolioTurnoverHeadingPortfolio Turnover:
Portfolio Turnover [Text Block]rr_PortfolioTurnoverTextBlockThe 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 period, the Fund’s portfolio turnover rate was 173% of the average value of its portfolio.
Portfolio Turnover, Raterr_PortfolioTurnoverRate173.00%
Principal Investment Strategiesjif277751_PrincipalInvestmentStrategiesAbstract 
Strategy [Heading]rr_StrategyHeadingPRINCIPAL 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 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 located in 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 floating rate loans, buy backs or dollar rolls, 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 an underlying asset, such as equity securities, bonds, commodities, currencies, interest rates, or market indices, as substitutes for securities in which the Fund invests. The Fund may use futures, options, and swaps (including interest rate swaps, total return swaps, and credit default swaps). The Fund may also invest in derivative instruments (by taking long and/or short positions) for other purposes, including hedging, 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. The Fund’s exposure to derivatives will vary, is not limited to those derivatives listed, and could be significant at times. For more information on the Fund’s use of derivatives, refer to the Fund’s shareholder reports and Form N-Q reports, which are filed with the Securities and Exchange Commission.

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 Risksjif277751_PrincipalInvestmentRisksAbstract 
Risk [Heading]rr_RiskHeadingPRINCIPAL 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 their value 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.

Mortgage-Backed Securities Risk. Mortgage-backed securities tend to be more sensitive to changes in interest rates than other types of 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.

Foreign Exposure Risk. The Fund normally has significant exposure to foreign markets, including 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. 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.

Emerging Markets Risk. The risks of foreign investing mentioned above are heightened when investing in emerging markets. Emerging markets securities are exposed to 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, 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 specialized risks. As of June 30, 2011, approximately 0.8% of the Fund’s investments were in emerging markets.

Sovereign Debt Risk. Investments in foreign government debt securities (“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.

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 common stocks, 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.

Floating Rate Loan Risk. There may be a number of intermediate participants in floating rate loan transactions and loan agreements have specific rights and obligations, and terms and conditions. Any number of factors in an investment in floating rate loans could cause the Fund to lose income or principal on a particular investment, which in turn could affect the Fund’s returns, and you could lose money. For the Fund’s secured or collateralized investments, lenders may have difficulty liquidating collateral, the collateral might decline in value or be insufficient, or the collateral might be set aside in a court proceeding such as a bankruptcy proceeding. There may be many claims by other lenders against the same collateral. The Fund could be held liable as a co-lender.

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 can be substantially greater than the derivative’s original cost, and can therefore involve 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_RiskLoseMoneyAlthough 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_RiskNotInsuredDepositoryInstitutionAn 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 INFORMATIONjif277751_FundPastPerformanceAbstract 
Bar Chart and Performance Table [Heading]rr_BarChartAndPerformanceTableHeadingPERFORMANCE INFORMATION
Performance Narrative [Text Block]rr_PerformanceNarrativeTextBlockThe Fund does not have a full calendar year of operations. Performance information for certain periods will be included in the Fund’s first annual and/or semiannual report.
Performance One Year or Less [Text]rr_PerformanceOneYearOrLessThe Fund does not have a full calendar year of operations.
Janus Global Bond Fund | Class D Shares | Class D
 
ANNUAL FUND OPERATING EXPENSESrr_OperatingExpensesAbstract 
Operating Expenses Column [Text]rr_OperatingExpensesColumnNameClass D
Management Feesrr_ManagementFeesOverAssets0.60%
Other Expensesrr_OtherExpensesOverAssets2.33%
Total Annual Fund Operating Expensesrr_ExpensesOverAssets2.93%[18]
Fee Waiverrr_FeeWaiverOrReimbursementOverAssets2.04%[18]
Net Annual Fund Operating Expenses After Fee Waiverrr_NetExpensesOverAssets0.89%[18]
EXAMPLE:rr_ExpenseExampleAbstract 
Expense Example, By Year, Column [Text]rr_ExpenseExampleByYearColumnNameClass D Shares
1 Yearrr_ExpenseExampleYear01296
3 Yearsrr_ExpenseExampleYear03907
5 Yearsrr_ExpenseExampleYear051,543
10 Yearsrr_ExpenseExampleYear103,252
Janus High-Yield Fund | Class A, C, S, I, R, T Shares
 
Risk/Return:rr_RiskReturnAbstract 
Risk/Return [Heading]rr_RiskReturnHeadingFUND SUMMARY Janus High-Yield Fund
Objective [Heading]rr_ObjectiveHeadingINVESTMENT OBJECTIVES
Objective, Primary [Text Block]rr_ObjectivePrimaryTextBlockJanus High-Yield Fund seeks to obtain high current income.
Objective, Secondary [Text Block]rr_ObjectiveSecondaryTextBlockCapital appreciation is a secondary investment objective when consistent with its primary investment objective.
FEES AND EXPENSES OF THE FUNDjif277751_FundFeesAndExpensesAbstract 
Expense [Heading]rr_ExpenseHeadingFEES AND EXPENSES OF THE FUND
Expense Narrative [Text Block]rr_ExpenseNarrativeTextBlockThis 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.
Expense Breakpoint Discountsjif277751_ExpenseBreakpointDiscountsAbstract 
Expense Breakpoint Discounts [Text]rr_ExpenseBreakpointDiscountsFor 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 44 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_ExpenseBreakpointMinimumInvestmentRequiredAmount50,000
SHAREHOLDER FEESrr_ShareholderFeesAbstract 
Shareholder Fees Caption [Text]rr_ShareholderFeesCaptionSHAREHOLDER FEES (fees paid directly from your investment)
ANNUAL FUND OPERATING EXPENSESrr_OperatingExpensesAbstract 
Operating Expenses Caption [Text]rr_OperatingExpensesCaptionANNUAL 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 Terminationrr_FeeWaiverOrReimbursementOverAssetsDateOfTerminationNovember 1, 2012
EXAMPLE:rr_ExpenseExampleAbstract 
Expense Example [Heading]rr_ExpenseExampleHeadingEXAMPLE:
Expense Example Narrative [Text Block]rr_ExpenseExampleNarrativeTextBlockThe 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 [Heading]rr_ExpenseExampleByYearHeadingThe 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 by, Year, Caption [Text]rr_ExpenseExampleByYearCaptionIf Shares are redeemed:
Expense Example, No Redemption:rr_ExpenseExampleNoRedemptionAbstract 
Expense Example, No Redemption, By Year, Caption [Text]rr_ExpenseExampleNoRedemptionByYearCaptionIf Shares are not redeemed:
Portfolio Turnover:jif277751_PortfolioTurnoverAltAbstract 
Portfolio Turnover [Heading]rr_PortfolioTurnoverHeadingPortfolio Turnover:
Portfolio Turnover [Text Block]rr_PortfolioTurnoverTextBlockThe 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 period, the Fund’s portfolio turnover rate was 92% of the average value of its portfolio.
Portfolio Turnover, Raterr_PortfolioTurnoverRate92.00%
Principal Investment Strategiesjif277751_PrincipalInvestmentStrategiesAbstract 
Strategy [Heading]rr_StrategyHeadingPRINCIPAL 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. Due to the nature of securities in which the Fund invests, it may have relatively high portfolio turnover compared to other funds.

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 also invest in foreign debt securities, which may include investments in emerging markets.

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 Risksjif277751_PrincipalInvestmentRisksAbstract 
Risk [Heading]rr_RiskHeadingPRINCIPAL 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 their value 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.

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.

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.

Foreign Exposure Risk. The Fund may have exposure to foreign markets, including 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. 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.

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_RiskLoseMoneyAlthough 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_RiskNotInsuredDepositoryInstitutionAn 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 INFORMATIONjif277751_FundPastPerformanceAbstract 
Bar Chart and Performance Table [Heading]rr_BarChartAndPerformanceTableHeadingPERFORMANCE 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.

• 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, without the effect of any 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, 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 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.

Bar Chart Does Not Reflect Sales Loads [Text]rr_BarChartDoesNotReflectSalesLoadsThe 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.
Performance Additional Market Index [Text]rr_PerformanceAdditionalMarketIndexThe 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 Past Does Not Indicate Future [Text]rr_PerformancePastDoesNotIndicateFutureThe Fund’s past performance (before and after taxes) does not necessarily indicate how it will perform in the future.
Performance Table Closing [Text Block]rr_PerformanceTableClosingTextBlockUpdated performance information is available at janus.com/advisor/mutual-funds or by calling 1-877-335-2687.
Performance Availability Website Address [Text]rr_PerformanceAvailabilityWebSiteAddressjanus.com/advisor/mutual-funds
Performance Availability Phone [Text]rr_PerformanceAvailabilityPhone1-877-335-2687
Annual Total Returnsrr_BarChartTableAbstract 
Bar Chart [Heading]rr_BarChartHeadingAnnual Total Returns for Class T 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, Labelrr_YearToDateReturnLabelThe Fund’s year-to-date return as of the calendar quarter ended September 30, 2011 was -2.55%.
Bar Chart, Year to Date Return, Daterr_BarChartYearToDateReturnDateSep. 30, 2011
Bar Chart, Year to Date Returnrr_BarChartYearToDateReturn(2.55%)
Average Annual Total Returnsrr_AverageAnnualReturnAbstract 
Captionrr_AverageAnnualReturnCaptionAverage Annual Total Returns (periods ended 12/31/10)
Performance Table Narrativerr_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 Uses Highest Federal Raterr_PerformanceTableUsesHighestFederalRateAfter-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 Deferredrr_PerformanceTableNotRelevantToTaxDeferredActual 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_PerformanceTableOneClassOfAfterTaxShownAfter-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.
Janus High-Yield Fund | Class A, C, S, I, R, T Shares | Class A
 
SHAREHOLDER FEESrr_ShareholderFeesAbstract 
Shareholder Fees Column [Text]rr_ShareholderFeesColumnNameClass A
Maximum Sales Charge (load) Imposed on Purchases (as a percentage of offering price)rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice4.75%
Maximum Deferred Sales Charge (load) (as a percentage of the lower of original purchase price or redemption proceeds)rr_MaximumDeferredSalesChargeOverOther none
Redemption fee on Shares held for 90 days or less (as a percentage of amount redeemed)rr_RedemptionFeeOverRedemption none
ANNUAL FUND OPERATING EXPENSESrr_OperatingExpensesAbstract 
Operating Expenses Column [Text]rr_OperatingExpensesColumnNameClass A
Management Feesrr_ManagementFeesOverAssets0.57%
Distribution/Service (12b-1) Feesrr_DistributionAndService12b1FeesOverAssets0.25%
Other Expensesrr_OtherExpensesOverAssets0.11%
Total Annual Fund Operating Expensesrr_ExpensesOverAssets0.93%[19]
EXAMPLE:rr_ExpenseExampleAbstract 
Expense Example, By Year, Column [Text]rr_ExpenseExampleByYearColumnNameClass A Shares
1 Yearrr_ExpenseExampleYear01565
3 Yearsrr_ExpenseExampleYear03757
5 Yearsrr_ExpenseExampleYear05965
10 Yearsrr_ExpenseExampleYear101,564
Expense Example, No Redemption:rr_ExpenseExampleNoRedemptionAbstract 
Expense Example, No Redemption, By Year, Column [Text]rr_ExpenseExampleNoRedemptionByYearColumnNameClass A Shares
1 Yearrr_ExpenseExampleNoRedemptionYear01565
3 Yearsrr_ExpenseExampleNoRedemptionYear03757
5 Yearsrr_ExpenseExampleNoRedemptionYear05965
10 Yearsrr_ExpenseExampleNoRedemptionYear101,564
Janus High-Yield Fund | Class A, C, S, I, R, T Shares | Class C
 
SHAREHOLDER FEESrr_ShareholderFeesAbstract 
Shareholder Fees Column [Text]rr_ShareholderFeesColumnNameClass 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_MaximumDeferredSalesChargeOverOther1.00%
Redemption fee on Shares held for 90 days or less (as a percentage of amount redeemed)rr_RedemptionFeeOverRedemption none
ANNUAL FUND OPERATING EXPENSESrr_OperatingExpensesAbstract 
Operating Expenses Column [Text]rr_OperatingExpensesColumnNameClass C
Management Feesrr_ManagementFeesOverAssets0.57%
Distribution/Service (12b-1) Feesrr_DistributionAndService12b1FeesOverAssets1.00%
Other Expensesrr_OtherExpensesOverAssets0.12%
Total Annual Fund Operating Expensesrr_ExpensesOverAssets1.69%[19]
EXAMPLE:rr_ExpenseExampleAbstract 
Expense Example, By Year, Column [Text]rr_ExpenseExampleByYearColumnNameClass C Shares
1 Yearrr_ExpenseExampleYear01272
3 Yearsrr_ExpenseExampleYear03533
5 Yearsrr_ExpenseExampleYear05918
10 Yearsrr_ExpenseExampleYear101,998
Expense Example, No Redemption:rr_ExpenseExampleNoRedemptionAbstract 
Expense Example, No Redemption, By Year, Column [Text]rr_ExpenseExampleNoRedemptionByYearColumnNameClass C Shares
1 Yearrr_ExpenseExampleNoRedemptionYear01172
3 Yearsrr_ExpenseExampleNoRedemptionYear03533
5 Yearsrr_ExpenseExampleNoRedemptionYear05918
10 Yearsrr_ExpenseExampleNoRedemptionYear101,998
Janus High-Yield Fund | Class A, C, S, I, R, T Shares | Class S
 
SHAREHOLDER FEESrr_ShareholderFeesAbstract 
Shareholder Fees Column [Text]rr_ShareholderFeesColumnNameClass 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
Redemption fee on Shares held for 90 days or less (as a percentage of amount redeemed)rr_RedemptionFeeOverRedemption2.00%
ANNUAL FUND OPERATING EXPENSESrr_OperatingExpensesAbstract 
Operating Expenses Column [Text]rr_OperatingExpensesColumnNameClass S
Management Feesrr_ManagementFeesOverAssets0.57%
Distribution/Service (12b-1) Feesrr_DistributionAndService12b1FeesOverAssets0.25%
Other Expensesrr_OtherExpensesOverAssets0.32%
Total Annual Fund Operating Expensesrr_ExpensesOverAssets1.14%[19]
EXAMPLE:rr_ExpenseExampleAbstract 
Expense Example, By Year, Column [Text]rr_ExpenseExampleByYearColumnNameClass S Shares
1 Yearrr_ExpenseExampleYear01116
3 Yearsrr_ExpenseExampleYear03362
5 Yearsrr_ExpenseExampleYear05628
10 Yearsrr_ExpenseExampleYear101,386
Expense Example, No Redemption:rr_ExpenseExampleNoRedemptionAbstract 
Expense Example, No Redemption, By Year, Column [Text]rr_ExpenseExampleNoRedemptionByYearColumnNameClass S Shares
1 Yearrr_ExpenseExampleNoRedemptionYear01116
3 Yearsrr_ExpenseExampleNoRedemptionYear03362
5 Yearsrr_ExpenseExampleNoRedemptionYear05628
10 Yearsrr_ExpenseExampleNoRedemptionYear101,386
Janus High-Yield Fund | Class A, C, S, I, R, T Shares | Class I
 
SHAREHOLDER FEESrr_ShareholderFeesAbstract 
Shareholder Fees Column [Text]rr_ShareholderFeesColumnNameClass 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
Redemption fee on Shares held for 90 days or less (as a percentage of amount redeemed)rr_RedemptionFeeOverRedemption2.00%
ANNUAL FUND OPERATING EXPENSESrr_OperatingExpensesAbstract 
Operating Expenses Column [Text]rr_OperatingExpensesColumnNameClass I
Management Feesrr_ManagementFeesOverAssets0.57%
Distribution/Service (12b-1) Feesrr_DistributionAndService12b1FeesOverAssets none
Other Expensesrr_OtherExpensesOverAssets0.14%
Total Annual Fund Operating Expensesrr_ExpensesOverAssets0.71%[19]
EXAMPLE:rr_ExpenseExampleAbstract 
Expense Example, By Year, Column [Text]rr_ExpenseExampleByYearColumnNameClass I Shares
1 Yearrr_ExpenseExampleYear0173
3 Yearsrr_ExpenseExampleYear03227
5 Yearsrr_ExpenseExampleYear05395
10 Yearsrr_ExpenseExampleYear10883
Expense Example, No Redemption:rr_ExpenseExampleNoRedemptionAbstract 
Expense Example, No Redemption, By Year, Column [Text]rr_ExpenseExampleNoRedemptionByYearColumnNameClass I Shares
1 Yearrr_ExpenseExampleNoRedemptionYear0173
3 Yearsrr_ExpenseExampleNoRedemptionYear03227
5 Yearsrr_ExpenseExampleNoRedemptionYear05395
10 Yearsrr_ExpenseExampleNoRedemptionYear10883
Janus High-Yield Fund | Class A, C, S, I, R, T Shares | Class R
 
SHAREHOLDER FEESrr_ShareholderFeesAbstract 
Shareholder Fees Column [Text]rr_ShareholderFeesColumnNameClass 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
Redemption fee on Shares held for 90 days or less (as a percentage of amount redeemed)rr_RedemptionFeeOverRedemption2.00%
ANNUAL FUND OPERATING EXPENSESrr_OperatingExpensesAbstract 
Operating Expenses Column [Text]rr_OperatingExpensesColumnNameClass R
Management Feesrr_ManagementFeesOverAssets0.57%
Distribution/Service (12b-1) Feesrr_DistributionAndService12b1FeesOverAssets0.50%
Other Expensesrr_OtherExpensesOverAssets0.27%
Total Annual Fund Operating Expensesrr_ExpensesOverAssets1.34%[19]
EXAMPLE:rr_ExpenseExampleAbstract 
Expense Example, By Year, Column [Text]rr_ExpenseExampleByYearColumnNameClass R Shares
1 Yearrr_ExpenseExampleYear01136
3 Yearsrr_ExpenseExampleYear03425
5 Yearsrr_ExpenseExampleYear05734
10 Yearsrr_ExpenseExampleYear101,613
Expense Example, No Redemption:rr_ExpenseExampleNoRedemptionAbstract 
Expense Example, No Redemption, By Year, Column [Text]rr_ExpenseExampleNoRedemptionByYearColumnNameClass R Shares
1 Yearrr_ExpenseExampleNoRedemptionYear01136
3 Yearsrr_ExpenseExampleNoRedemptionYear03425
5 Yearsrr_ExpenseExampleNoRedemptionYear05734
10 Yearsrr_ExpenseExampleNoRedemptionYear101,613
Janus High-Yield Fund | Class A, C, S, I, R, T Shares | Class T
 
SHAREHOLDER FEESrr_ShareholderFeesAbstract 
Shareholder Fees Column [Text]rr_ShareholderFeesColumnNameClass 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
Redemption fee on Shares held for 90 days or less (as a percentage of amount redeemed)rr_RedemptionFeeOverRedemption2.00%
ANNUAL FUND OPERATING EXPENSESrr_OperatingExpensesAbstract 
Operating Expenses Column [Text]rr_OperatingExpensesColumnNameClass T
Management Feesrr_ManagementFeesOverAssets0.57%
Distribution/Service (12b-1) Feesrr_DistributionAndService12b1FeesOverAssets none
Other Expensesrr_OtherExpensesOverAssets0.32%
Total Annual Fund Operating Expensesrr_ExpensesOverAssets0.89%[19]
EXAMPLE:rr_ExpenseExampleAbstract 
Expense Example, By Year, Column [Text]rr_ExpenseExampleByYearColumnNameClass T Shares
1 Yearrr_ExpenseExampleYear0191
3 Yearsrr_ExpenseExampleYear03284
5 Yearsrr_ExpenseExampleYear05493
10 Yearsrr_ExpenseExampleYear101,096
Expense Example, No Redemption:rr_ExpenseExampleNoRedemptionAbstract 
Expense Example, No Redemption, By Year, Column [Text]rr_ExpenseExampleNoRedemptionByYearColumnNameClass T Shares
1 Yearrr_ExpenseExampleNoRedemptionYear0191
3 Yearsrr_ExpenseExampleNoRedemptionYear03284
5 Yearsrr_ExpenseExampleNoRedemptionYear05493
10 Yearsrr_ExpenseExampleNoRedemptionYear101,096
Annual Total Returnsrr_BarChartTableAbstract 
2001rr_AnnualReturn20014.59%
2002rr_AnnualReturn20022.56%
2003rr_AnnualReturn200316.04%
2004rr_AnnualReturn20049.42%
2005rr_AnnualReturn20052.77%
2006rr_AnnualReturn200611.10%
2007rr_AnnualReturn20071.35%
2008rr_AnnualReturn2008(19.32%)
2009rr_AnnualReturn200940.86%
2010rr_AnnualReturn201015.72%
Highest Quarterly Return, Labelrr_HighestQuarterlyReturnLabelBest Quarter:
Highest Quarterly Return, Daterr_BarChartHighestQuarterlyReturnDateJun. 30, 2009
Highest Quarterly Returnrr_BarChartHighestQuarterlyReturn14.93%
Lowest Quarterly Return, Labelrr_LowestQuarterlyReturnLabelWorst Quarter:
Lowest Quarterly Return, Daterr_BarChartLowestQuarterlyReturnDateDec. 31, 2008
Lowest Quarterly Returnrr_BarChartLowestQuarterlyReturn(12.96%)
Janus High-Yield Fund | Class A, C, S, I, R, T Shares | Return Before Taxes | Class A
 
Average Annual Total Returnsrr_AverageAnnualReturnAbstract 
Columnrr_AverageAnnualReturnColumnNameClass A Shares
Labelrr_AverageAnnualReturnLabelReturn Before Taxes[3]
1 Yearrr_AverageAnnualReturnYear0110.21%
5 Yearsrr_AverageAnnualReturnYear057.01%
10 Yearsrr_AverageAnnualReturnYear106.97%
Since Inceptionrr_AverageAnnualReturnSinceInception7.75%
Inception Daterr_AverageAnnualReturnInceptionDateDec. 29, 1995
Janus High-Yield Fund | Class A, C, S, I, R, T Shares | Return Before Taxes | Class C
 
Average Annual Total Returnsrr_AverageAnnualReturnAbstract 
Columnrr_AverageAnnualReturnColumnNameClass C Shares
Labelrr_AverageAnnualReturnLabelReturn Before Taxes[4]
1 Yearrr_AverageAnnualReturnYear0113.74%
5 Yearsrr_AverageAnnualReturnYear057.33%
10 Yearsrr_AverageAnnualReturnYear106.74%
Since Inceptionrr_AverageAnnualReturnSinceInception7.34%
Inception Daterr_AverageAnnualReturnInceptionDateDec. 29, 1995
Janus High-Yield Fund | Class A, C, S, I, R, T Shares | Return Before Taxes | Class S
 
Average Annual Total Returnsrr_AverageAnnualReturnAbstract 
Columnrr_AverageAnnualReturnColumnNameClass S Shares
Labelrr_AverageAnnualReturnLabelReturn Before Taxes
1 Yearrr_AverageAnnualReturnYear0115.55%
5 Yearsrr_AverageAnnualReturnYear057.86%
10 Yearsrr_AverageAnnualReturnYear107.26%
Since Inceptionrr_AverageAnnualReturnSinceInception7.87%
Inception Daterr_AverageAnnualReturnInceptionDateDec. 29, 1995
Janus High-Yield Fund | Class A, C, S, I, R, T Shares | Return Before Taxes | Class I
 
Average Annual Total Returnsrr_AverageAnnualReturnAbstract 
Columnrr_AverageAnnualReturnColumnNameClass I Shares
Labelrr_AverageAnnualReturnLabelReturn Before Taxes
1 Yearrr_AverageAnnualReturnYear0115.97%
5 Yearsrr_AverageAnnualReturnYear058.17%
10 Yearsrr_AverageAnnualReturnYear107.56%
Since Inceptionrr_AverageAnnualReturnSinceInception8.15%
Inception Daterr_AverageAnnualReturnInceptionDateDec. 29, 1995
Janus High-Yield Fund | Class A, C, S, I, R, T Shares | Return Before Taxes | Class R
 
Average Annual Total Returnsrr_AverageAnnualReturnAbstract 
Columnrr_AverageAnnualReturnColumnNameClass R Shares
Labelrr_AverageAnnualReturnLabelReturn Before Taxes
1 Yearrr_AverageAnnualReturnYear0115.15%
5 Yearsrr_AverageAnnualReturnYear057.57%
10 Yearsrr_AverageAnnualReturnYear106.99%
Since Inceptionrr_AverageAnnualReturnSinceInception7.60%
Inception Daterr_AverageAnnualReturnInceptionDateDec. 29, 1995
Janus High-Yield Fund | Class A, C, S, I, R, T Shares | Return Before Taxes | Class T
 
Average Annual Total Returnsrr_AverageAnnualReturnAbstract 
Columnrr_AverageAnnualReturnColumnNameClass T Shares
Labelrr_AverageAnnualReturnLabelReturn Before Taxes
1 Yearrr_AverageAnnualReturnYear0115.72%
5 Yearsrr_AverageAnnualReturnYear058.17%
10 Yearsrr_AverageAnnualReturnYear107.56%
Since Inceptionrr_AverageAnnualReturnSinceInception8.15%
Inception Daterr_AverageAnnualReturnInceptionDateDec. 29, 1995
Janus High-Yield Fund | Class A, C, S, I, R, T Shares | Return After Taxes on Distributions | Class T
 
Average Annual Total Returnsrr_AverageAnnualReturnAbstract 
Columnrr_AverageAnnualReturnColumnNameClass T Shares
Labelrr_AverageAnnualReturnLabelReturn After Taxes on Distributions
1 Yearrr_AverageAnnualReturnYear0112.62%
5 Yearsrr_AverageAnnualReturnYear054.90%
10 Yearsrr_AverageAnnualReturnYear104.57%
Since Inceptionrr_AverageAnnualReturnSinceInception4.81%
Inception Daterr_AverageAnnualReturnInceptionDateDec. 29, 1995
Janus High-Yield Fund | Class A, C, S, I, R, T Shares | Return After Taxes on Distributions and Sale of Fund Shares | Class T
 
Average Annual Total Returnsrr_AverageAnnualReturnAbstract 
Columnrr_AverageAnnualReturnColumnNameClass T Shares
Labelrr_AverageAnnualReturnLabelReturn After Taxes on Distributions and Sale of Fund Shares[5]
1 Yearrr_AverageAnnualReturnYear0110.06%
5 Yearsrr_AverageAnnualReturnYear054.96%
10 Yearsrr_AverageAnnualReturnYear104.61%
Since Inceptionrr_AverageAnnualReturnSinceInception4.88%
Inception Daterr_AverageAnnualReturnInceptionDateDec. 29, 1995
Janus High-Yield Fund | Class A, C, S, I, R, T Shares | Barclays Capital U.S. Corporate High-Yield Bond Index
 
Average Annual Total Returnsrr_AverageAnnualReturnAbstract 
Labelrr_AverageAnnualReturnLabelBarclays Capital U.S. Corporate High-Yield Bond Index
Index No Deduction for Fees, Expenses, Taxes [Text]rr_IndexNoDeductionForFeesExpensesTaxes(reflects no deduction for expenses, fees, or taxes)
1 Yearrr_AverageAnnualReturnYear0115.12%
5 Yearsrr_AverageAnnualReturnYear058.91%
10 Yearsrr_AverageAnnualReturnYear108.88%
Since Inceptionrr_AverageAnnualReturnSinceInception7.32%
Inception Daterr_AverageAnnualReturnInceptionDateDec. 29, 1995
Janus High-Yield Fund | Class D Shares
 
Risk/Return:rr_RiskReturnAbstract 
Risk/Return [Heading]rr_RiskReturnHeadingFUND SUMMARY Janus High-Yield Fund
Objective [Heading]rr_ObjectiveHeadingINVESTMENT OBJECTIVES
Objective, Primary [Text Block]rr_ObjectivePrimaryTextBlockJanus High-Yield Fund seeks to obtain high current income.
Objective, Secondary [Text Block]rr_ObjectiveSecondaryTextBlockCapital appreciation is a secondary investment objective when consistent with its primary investment objective.
FEES AND EXPENSES OF THE FUNDjif277751_FundFeesAndExpensesAbstract 
Expense [Heading]rr_ExpenseHeadingFEES AND EXPENSES OF THE FUND
Expense Narrative [Text Block]rr_ExpenseNarrativeTextBlockThis table describes the fees and expenses that you may pay if you buy and hold Shares of the Fund.
SHAREHOLDER FEESrr_ShareholderFeesAbstract 
Shareholder Fees Caption [Text]rr_ShareholderFeesCaptionSHAREHOLDER FEES (fees paid directly from your investment)
ANNUAL FUND OPERATING EXPENSESrr_OperatingExpensesAbstract 
Operating Expenses Caption [Text]rr_OperatingExpensesCaptionANNUAL 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 Terminationrr_FeeWaiverOrReimbursementOverAssetsDateOfTerminationNovember 1, 2012
EXAMPLE:rr_ExpenseExampleAbstract 
Expense Example [Heading]rr_ExpenseExampleHeadingEXAMPLE:
Expense Example Narrative [Text Block]rr_ExpenseExampleNarrativeTextBlockThe 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 [Heading]rr_ExpenseExampleByYearHeadingThe 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:
Portfolio Turnover:jif277751_PortfolioTurnoverAltAbstract 
Portfolio Turnover [Heading]rr_PortfolioTurnoverHeadingPortfolio Turnover:
Portfolio Turnover [Text Block]rr_PortfolioTurnoverTextBlockThe 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 period, the Fund’s portfolio turnover rate was 92% of the average value of its portfolio.
Portfolio Turnover, Raterr_PortfolioTurnoverRate92.00%
Principal Investment Strategiesjif277751_PrincipalInvestmentStrategiesAbstract 
Strategy [Heading]rr_StrategyHeadingPRINCIPAL 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. Due to the nature of securities in which the Fund invests, it may have relatively high portfolio turnover compared to other funds.

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 also invest in foreign debt securities, which may include investments in emerging markets.

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 Risksjif277751_PrincipalInvestmentRisksAbstract 
Risk [Heading]rr_RiskHeadingPRINCIPAL 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 their value 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.

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.

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.

Foreign Exposure Risk. The Fund may have exposure to foreign markets, including 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. 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.

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_RiskLoseMoneyAlthough 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_RiskNotInsuredDepositoryInstitutionAn 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 INFORMATIONjif277751_FundPastPerformanceAbstract 
Bar Chart and Performance Table [Heading]rr_BarChartAndPerformanceTableHeadingPERFORMANCE 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_PerformanceAdditionalMarketIndexThe 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 Past Does Not Indicate Future [Text]rr_PerformancePastDoesNotIndicateFutureThe Fund’s past performance (before and after taxes) does not necessarily indicate how it will perform in the future.
Performance Table Closing [Text Block]rr_PerformanceTableClosingTextBlockUpdated performance information is available at janus.com/allfunds or by calling 1-800-525-3713.
Performance Availability Website Address [Text]rr_PerformanceAvailabilityWebSiteAddressjanus.com/allfunds
Performance Availability Phone [Text]rr_PerformanceAvailabilityPhone1-800-525-3713
Annual Total Returnsrr_BarChartTableAbstract 
Bar Chart [Heading]rr_BarChartHeadingAnnual Total Returns for Class D Shares (calendar year-end)
Bar Chart Closing [Text Block]rr_BarChartClosingTextBlockBest Quarter: Second Quarter 2009 14.93%          Worst Quarter: Fourth Quarter 2008 -12.96%
Year to Date Return, Labelrr_YearToDateReturnLabelThe Fund’s year-to-date return as of the calendar quarter ended September 30, 2011 was -2.46%.
Bar Chart, Year to Date Return, Daterr_BarChartYearToDateReturnDateSep. 30, 2011
Bar Chart, Year to Date Returnrr_BarChartYearToDateReturn(2.46%)
Average Annual Total Returnsrr_AverageAnnualReturnAbstract 
Captionrr_AverageAnnualReturnCaptionAverage Annual Total Returns (periods ended 12/31/10)
Performance Table Narrativerr_PerformanceTableNarrativeTextBlockAfter-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 Uses Highest Federal Raterr_PerformanceTableUsesHighestFederalRateAfter-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 Deferredrr_PerformanceTableNotRelevantToTaxDeferredActual 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.
Janus High-Yield Fund | Class D Shares | Class D
 
SHAREHOLDER FEESrr_ShareholderFeesAbstract 
Shareholder Fees Column [Text]rr_ShareholderFeesColumnNameClass D
Redemption fee on Shares held for 90 days or less (as a percentage of amount redeemed)rr_RedemptionFeeOverRedemption2.00%
ANNUAL FUND OPERATING EXPENSESrr_OperatingExpensesAbstract 
Operating Expenses Column [Text]rr_OperatingExpensesColumnNameClass D
Management Feesrr_ManagementFeesOverAssets0.57%
Other Expensesrr_OtherExpensesOverAssets0.20%
Total Annual Fund Operating Expensesrr_ExpensesOverAssets0.77%[20]
EXAMPLE:rr_ExpenseExampleAbstract 
Expense Example, By Year, Column [Text]rr_ExpenseExampleByYearColumnNameClass D Shares
1 Yearrr_ExpenseExampleYear0179
3 Yearsrr_ExpenseExampleYear03246
5 Yearsrr_ExpenseExampleYear05428
10 Yearsrr_ExpenseExampleYear10954
Annual Total Returnsrr_BarChartTableAbstract 
2001rr_AnnualReturn20014.59%
2002rr_AnnualReturn20022.56%
2003rr_AnnualReturn200316.04%
2004rr_AnnualReturn20049.42%
2005rr_AnnualReturn20052.77%
2006rr_AnnualReturn200611.10%
2007rr_AnnualReturn20071.35%
2008rr_AnnualReturn2008(19.32%)
2009rr_AnnualReturn200940.86%
2010rr_AnnualReturn201015.80%
Highest Quarterly Return, Labelrr_HighestQuarterlyReturnLabelBest Quarter:
Highest Quarterly Return, Daterr_BarChartHighestQuarterlyReturnDateJun. 30, 2009
Highest Quarterly Returnrr_BarChartHighestQuarterlyReturn14.93%
Lowest Quarterly Return, Labelrr_LowestQuarterlyReturnLabelWorst Quarter:
Lowest Quarterly Return, Daterr_BarChartLowestQuarterlyReturnDateDec. 31, 2008
Lowest Quarterly Returnrr_BarChartLowestQuarterlyReturn(12.96%)
Janus High-Yield Fund | Class D Shares | Return Before Taxes | Class D
 
Average Annual Total Returnsrr_AverageAnnualReturnAbstract 
Columnrr_AverageAnnualReturnColumnNameClass D Shares
Labelrr_AverageAnnualReturnLabelReturn Before Taxes
1 Yearrr_AverageAnnualReturnYear0115.80%
5 Yearsrr_AverageAnnualReturnYear058.18%
10 Yearsrr_AverageAnnualReturnYear107.57%
Since Inceptionrr_AverageAnnualReturnSinceInception8.15%
Inception Daterr_AverageAnnualReturnInceptionDateDec. 29, 1995
Janus High-Yield Fund | Class D Shares | Return After Taxes on Distributions | Class D
 
Average Annual Total Returnsrr_AverageAnnualReturnAbstract 
Columnrr_AverageAnnualReturnColumnNameClass D Shares
Labelrr_AverageAnnualReturnLabelReturn After Taxes on Distributions
1 Yearrr_AverageAnnualReturnYear0112.67%
5 Yearsrr_AverageAnnualReturnYear054.91%
10 Yearsrr_AverageAnnualReturnYear104.57%
Since Inceptionrr_AverageAnnualReturnSinceInception4.81%
Inception Daterr_AverageAnnualReturnInceptionDateDec. 29, 1995
Janus High-Yield Fund | Class D Shares | Return After Taxes on Distributions and Sale of Fund Shares | Class D
 
Average Annual Total Returnsrr_AverageAnnualReturnAbstract 
Columnrr_AverageAnnualReturnColumnNameClass D Shares
Labelrr_AverageAnnualReturnLabelReturn After Taxes on Distributions and Sale of Fund Shares[5]
1 Yearrr_AverageAnnualReturnYear0110.11%
5 Yearsrr_AverageAnnualReturnYear054.97%
10 Yearsrr_AverageAnnualReturnYear104.62%
Since Inceptionrr_AverageAnnualReturnSinceInception4.88%
Inception Daterr_AverageAnnualReturnInceptionDateDec. 29, 1995
Janus High-Yield Fund | Class D Shares | Barclays Capital U.S. Corporate High-Yield Bond Index
 
Average Annual Total Returnsrr_AverageAnnualReturnAbstract 
Labelrr_AverageAnnualReturnLabelBarclays Capital U.S. Corporate High-Yield Bond Index
Index No Deduction for Fees, Expenses, Taxes [Text]rr_IndexNoDeductionForFeesExpensesTaxes(reflects no deduction for expenses, fees, or taxes)
1 Yearrr_AverageAnnualReturnYear0115.12%
5 Yearsrr_AverageAnnualReturnYear058.91%
10 Yearsrr_AverageAnnualReturnYear108.88%
Since Inceptionrr_AverageAnnualReturnSinceInception7.32%
Inception Daterr_AverageAnnualReturnInceptionDateDec. 29, 1995
Janus Short-Term Bond Fund | Class A, C, S, I, T Shares
 
Risk/Return:rr_RiskReturnAbstract 
Risk/Return [Heading]rr_RiskReturnHeadingFUND SUMMARY Janus Short-Term Bond Fund
Objective [Heading]rr_ObjectiveHeadingINVESTMENT OBJECTIVE
Objective, Primary [Text Block]rr_ObjectivePrimaryTextBlockJanus Short-Term Bond Fund seeks as high a level of current income as is consistent with preservation of capital.
FEES AND EXPENSES OF THE FUNDjif277751_FundFeesAndExpensesAbstract 
Expense [Heading]rr_ExpenseHeadingFEES AND EXPENSES OF THE FUND
Expense Narrative [Text Block]rr_ExpenseNarrativeTextBlockThis 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.
Expense Breakpoint Discountsjif277751_ExpenseBreakpointDiscountsAbstract 
Expense Breakpoint Discounts [Text]rr_ExpenseBreakpointDiscountsFor 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 44 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_ExpenseBreakpointMinimumInvestmentRequiredAmount50,000
SHAREHOLDER FEESrr_ShareholderFeesAbstract 
Shareholder Fees Caption [Text]rr_ShareholderFeesCaptionSHAREHOLDER FEES (fees paid directly from your investment)
ANNUAL FUND OPERATING EXPENSESrr_OperatingExpensesAbstract 
Operating Expenses Caption [Text]rr_OperatingExpensesCaptionANNUAL 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 Terminationrr_FeeWaiverOrReimbursementOverAssetsDateOfTerminationNovember 1, 2012
EXAMPLE:rr_ExpenseExampleAbstract 
Expense Example [Heading]rr_ExpenseExampleHeadingEXAMPLE:
Expense Example Narrative [Text Block]rr_ExpenseExampleNarrativeTextBlockThe 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 [Heading]rr_ExpenseExampleByYearHeadingThe 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 by, Year, Caption [Text]rr_ExpenseExampleByYearCaptionIf Shares are redeemed:
Expense Example, No Redemption:rr_ExpenseExampleNoRedemptionAbstract 
Expense Example, No Redemption, By Year, Caption [Text]rr_ExpenseExampleNoRedemptionByYearCaptionIf Shares are not redeemed:
Portfolio Turnover:jif277751_PortfolioTurnoverAltAbstract 
Portfolio Turnover [Heading]rr_PortfolioTurnoverHeadingPortfolio Turnover:
Portfolio Turnover [Text Block]rr_PortfolioTurnoverTextBlockThe 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 period, the Fund’s portfolio turnover rate was 100% of the average value of its portfolio.
Portfolio Turnover, Raterr_PortfolioTurnoverRate100.00%
Principal Investment Strategiesjif277751_PrincipalInvestmentStrategiesAbstract 
Strategy [Heading]rr_StrategyHeadingPRINCIPAL 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. 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 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 also invest in foreign debt securities, which may include investments in emerging markets.

The Fund may invest its assets in derivatives, which are instruments that have a value derived from an underlying asset, such as equity securities, bonds, 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. For more information on the Fund’s use of derivatives, refer to the Fund’s shareholder reports and Form N-Q reports, which are filed with the Securities and Exchange Commission.

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 Risksjif277751_PrincipalInvestmentRisksAbstract 
Risk [Heading]rr_RiskHeadingPRINCIPAL 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 their value 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.

Mortgage-Backed Securities Risk. Mortgage-backed securities tend to be more sensitive to changes in interest rates than other types of 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.

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.

Foreign Exposure Risk. The Fund may have exposure to foreign markets, including 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. 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.

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 can be substantially greater than the derivative’s original cost, and can therefore involve 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_RiskLoseMoneyAlthough 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_RiskNotInsuredDepositoryInstitutionAn 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 INFORMATIONjif277751_FundPastPerformanceAbstract 
Bar Chart and Performance Table [Heading]rr_BarChartAndPerformanceTableHeadingPERFORMANCE 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. 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.

Bar Chart Does Not Reflect Sales Loads [Text]rr_BarChartDoesNotReflectSalesLoadsThe 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.
Performance Additional Market Index [Text]rr_PerformanceAdditionalMarketIndexThe 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 Past Does Not Indicate Future [Text]rr_PerformancePastDoesNotIndicateFutureThe Fund’s past performance (before and after taxes) does not necessarily indicate how it will perform in the future.
Performance Table Closing [Text Block]rr_PerformanceTableClosingTextBlockUpdated performance information is available at janus.com/advisor/mutual-funds or by calling 1-877-335-2687.
Performance Availability Website Address [Text]rr_PerformanceAvailabilityWebSiteAddressjanus.com/advisor/mutual-funds
Performance Availability Phone [Text]rr_PerformanceAvailabilityPhone1-877-335-2687
Annual Total Returnsrr_BarChartTableAbstract 
Bar Chart [Heading]rr_BarChartHeadingAnnual Total Returns for Class T Shares (calendar year-end)
Bar Chart Closing [Text Block]rr_BarChartClosingTextBlockBest Quarter: Second Quarter 2009 3.18%          Worst Quarter: Second Quarter 2008 -0.90%
Year to Date Return, Labelrr_YearToDateReturnLabelThe Fund’s year-to-date return as of the calendar quarter ended September 30, 2011 was 0.95%.
Bar Chart, Year to Date Return, Daterr_BarChartYearToDateReturnDateSep. 30, 2011
Bar Chart, Year to Date Returnrr_BarChartYearToDateReturn0.95%
Average Annual Total Returnsrr_AverageAnnualReturnAbstract 
Captionrr_AverageAnnualReturnCaptionAverage Annual Total Returns (periods ended 12/31/10)
Performance Table Narrativerr_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 Uses Highest Federal Raterr_PerformanceTableUsesHighestFederalRateAfter-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 Deferredrr_PerformanceTableNotRelevantToTaxDeferredActual 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_PerformanceTableOneClassOfAfterTaxShownAfter-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.
Janus Short-Term Bond Fund | Class A, C, S, I, T Shares | Class A
 
SHAREHOLDER FEESrr_ShareholderFeesAbstract 
Shareholder Fees Column [Text]rr_ShareholderFeesColumnNameClass A
Maximum Sales Charge (load) Imposed on Purchases (as a percentage of offering price)rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice2.50%
Maximum Deferred Sales Charge (load) (as a percentage of the lower of original purchase price or redemption proceeds)rr_MaximumDeferredSalesChargeOverOther none
ANNUAL FUND OPERATING EXPENSESrr_OperatingExpensesAbstract 
Operating Expenses Column [Text]rr_OperatingExpensesColumnNameClass A
Management Feesrr_ManagementFeesOverAssets0.55%
Distribution/Service (12b-1) Feesrr_DistributionAndService12b1FeesOverAssets0.25%
Other Expensesrr_OtherExpensesOverAssets0.09%
Total Annual Fund Operating Expensesrr_ExpensesOverAssets0.89%[21]
Fee Waiverrr_FeeWaiverOrReimbursementOverAssets0.09%[21]
Net Annual Fund Operating Expenses After Fee Waiverrr_NetExpensesOverAssets0.80%[21]
EXAMPLE:rr_ExpenseExampleAbstract 
Expense Example, By Year, Column [Text]rr_ExpenseExampleByYearColumnNameClass A Shares
1 Yearrr_ExpenseExampleYear01339
3 Yearsrr_ExpenseExampleYear03527
5 Yearsrr_ExpenseExampleYear05731
10 Yearsrr_ExpenseExampleYear101,319
Expense Example, No Redemption:rr_ExpenseExampleNoRedemptionAbstract 
Expense Example, No Redemption, By Year, Column [Text]rr_ExpenseExampleNoRedemptionByYearColumnNameClass A Shares
1 Yearrr_ExpenseExampleNoRedemptionYear01339
3 Yearsrr_ExpenseExampleNoRedemptionYear03527
5 Yearsrr_ExpenseExampleNoRedemptionYear05731
10 Yearsrr_ExpenseExampleNoRedemptionYear101,319
Janus Short-Term Bond Fund | Class A, C, S, I, T Shares | Class C
 
SHAREHOLDER FEESrr_ShareholderFeesAbstract 
Shareholder Fees Column [Text]rr_ShareholderFeesColumnNameClass 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_MaximumDeferredSalesChargeOverOther1.00%
ANNUAL FUND OPERATING EXPENSESrr_OperatingExpensesAbstract 
Operating Expenses Column [Text]rr_OperatingExpensesColumnNameClass C
Management Feesrr_ManagementFeesOverAssets0.55%
Distribution/Service (12b-1) Feesrr_DistributionAndService12b1FeesOverAssets1.00%
Other Expensesrr_OtherExpensesOverAssets0.10%
Total Annual Fund Operating Expensesrr_ExpensesOverAssets1.65%[21]
Fee Waiverrr_FeeWaiverOrReimbursementOverAssets0.10%[21]
Net Annual Fund Operating Expenses After Fee Waiverrr_NetExpensesOverAssets1.55%[21]
EXAMPLE:rr_ExpenseExampleAbstract 
Expense Example, By Year, Column [Text]rr_ExpenseExampleByYearColumnNameClass C Shares
1 Yearrr_ExpenseExampleYear01268
3 Yearsrr_ExpenseExampleYear03520
5 Yearsrr_ExpenseExampleYear05897
10 Yearsrr_ExpenseExampleYear101,955
Expense Example, No Redemption:rr_ExpenseExampleNoRedemptionAbstract 
Expense Example, No Redemption, By Year, Column [Text]rr_ExpenseExampleNoRedemptionByYearColumnNameClass C Shares
1 Yearrr_ExpenseExampleNoRedemptionYear01168
3 Yearsrr_ExpenseExampleNoRedemptionYear03520
5 Yearsrr_ExpenseExampleNoRedemptionYear05897
10 Yearsrr_ExpenseExampleNoRedemptionYear101,955
Janus Short-Term Bond Fund | Class A, C, S, I, T Shares | Class S
 
SHAREHOLDER FEESrr_ShareholderFeesAbstract 
Shareholder Fees Column [Text]rr_ShareholderFeesColumnNameClass 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
ANNUAL FUND OPERATING EXPENSESrr_OperatingExpensesAbstract 
Operating Expenses Column [Text]rr_OperatingExpensesColumnNameClass S
Management Feesrr_ManagementFeesOverAssets0.55%
Distribution/Service (12b-1) Feesrr_DistributionAndService12b1FeesOverAssets0.25%
Other Expensesrr_OtherExpensesOverAssets0.29%
Total Annual Fund Operating Expensesrr_ExpensesOverAssets1.09%[21]
Fee Waiverrr_FeeWaiverOrReimbursementOverAssets0.04%[21]
Net Annual Fund Operating Expenses After Fee Waiverrr_NetExpensesOverAssets1.05%[21]
EXAMPLE:rr_ExpenseExampleAbstract 
Expense Example, By Year, Column [Text]rr_ExpenseExampleByYearColumnNameClass S Shares
1 Yearrr_ExpenseExampleYear01111
3 Yearsrr_ExpenseExampleYear03347
5 Yearsrr_ExpenseExampleYear05601
10 Yearsrr_ExpenseExampleYear101,329
Expense Example, No Redemption:rr_ExpenseExampleNoRedemptionAbstract 
Expense Example, No Redemption, By Year, Column [Text]rr_ExpenseExampleNoRedemptionByYearColumnNameClass S Shares
1 Yearrr_ExpenseExampleNoRedemptionYear01111
3 Yearsrr_ExpenseExampleNoRedemptionYear03347
5 Yearsrr_ExpenseExampleNoRedemptionYear05601
10 Yearsrr_ExpenseExampleNoRedemptionYear101,329
Janus Short-Term Bond Fund | Class A, C, S, I, T Shares | Class I
 
SHAREHOLDER FEESrr_ShareholderFeesAbstract 
Shareholder Fees Column [Text]rr_ShareholderFeesColumnNameClass 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
ANNUAL FUND OPERATING EXPENSESrr_OperatingExpensesAbstract 
Operating Expenses Column [Text]rr_OperatingExpensesColumnNameClass I
Management Feesrr_ManagementFeesOverAssets0.55%
Distribution/Service (12b-1) Feesrr_DistributionAndService12b1FeesOverAssets none
Other Expensesrr_OtherExpensesOverAssets0.09%
Total Annual Fund Operating Expensesrr_ExpensesOverAssets0.64%[21]
Fee Waiverrr_FeeWaiverOrReimbursementOverAssets0.09%[21]
Net Annual Fund Operating Expenses After Fee Waiverrr_NetExpensesOverAssets0.55%[21]
EXAMPLE:rr_ExpenseExampleAbstract 
Expense Example, By Year, Column [Text]rr_ExpenseExampleByYearColumnNameClass I Shares
1 Yearrr_ExpenseExampleYear0165
3 Yearsrr_ExpenseExampleYear03205
5 Yearsrr_ExpenseExampleYear05357
10 Yearsrr_ExpenseExampleYear10798
Expense Example, No Redemption:rr_ExpenseExampleNoRedemptionAbstract 
Expense Example, No Redemption, By Year, Column [Text]rr_ExpenseExampleNoRedemptionByYearColumnNameClass I Shares
1 Yearrr_ExpenseExampleNoRedemptionYear0165
3 Yearsrr_ExpenseExampleNoRedemptionYear03205
5 Yearsrr_ExpenseExampleNoRedemptionYear05357
10 Yearsrr_ExpenseExampleNoRedemptionYear10798
Janus Short-Term Bond Fund | Class A, C, S, I, T Shares | Class T
 
SHAREHOLDER FEESrr_ShareholderFeesAbstract 
Shareholder Fees Column [Text]rr_ShareholderFeesColumnNameClass 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
ANNUAL FUND OPERATING EXPENSESrr_OperatingExpensesAbstract 
Operating Expenses Column [Text]rr_OperatingExpensesColumnNameClass T
Management Feesrr_ManagementFeesOverAssets0.55%
Distribution/Service (12b-1) Feesrr_DistributionAndService12b1FeesOverAssets none
Other Expensesrr_OtherExpensesOverAssets0.30%
Total Annual Fund Operating Expensesrr_ExpensesOverAssets0.85%[21]
Fee Waiverrr_FeeWaiverOrReimbursementOverAssets0.05%[21]
Net Annual Fund Operating Expenses After Fee Waiverrr_NetExpensesOverAssets0.80%[21]
EXAMPLE:rr_ExpenseExampleAbstract 
Expense Example, By Year, Column [Text]rr_ExpenseExampleByYearColumnNameClass T Shares
1 Yearrr_ExpenseExampleYear0187
3 Yearsrr_ExpenseExampleYear03271
5 Yearsrr_ExpenseExampleYear05471
10 Yearsrr_ExpenseExampleYear101,049
Expense Example, No Redemption:rr_ExpenseExampleNoRedemptionAbstract 
Expense Example, No Redemption, By Year, Column [Text]rr_ExpenseExampleNoRedemptionByYearColumnNameClass T Shares
1 Yearrr_ExpenseExampleNoRedemptionYear0187
3 Yearsrr_ExpenseExampleNoRedemptionYear03271
5 Yearsrr_ExpenseExampleNoRedemptionYear05471
10 Yearsrr_ExpenseExampleNoRedemptionYear101,049
Annual Total Returnsrr_BarChartTableAbstract 
2001rr_AnnualReturn20016.85%
2002rr_AnnualReturn20023.57%
2003rr_AnnualReturn20033.91%
2004rr_AnnualReturn20041.96%
2005rr_AnnualReturn20051.52%
2006rr_AnnualReturn20064.21%
2007rr_AnnualReturn20075.21%
2008rr_AnnualReturn20084.63%
2009rr_AnnualReturn20098.56%
2010rr_AnnualReturn20103.37%
Highest Quarterly Return, Labelrr_HighestQuarterlyReturnLabelBest Quarter:
Highest Quarterly Return, Daterr_BarChartHighestQuarterlyReturnDateJun. 30, 2009
Highest Quarterly Returnrr_BarChartHighestQuarterlyReturn3.18%
Lowest Quarterly Return, Labelrr_LowestQuarterlyReturnLabelWorst Quarter:
Lowest Quarterly Return, Daterr_BarChartLowestQuarterlyReturnDateJun. 30, 2008
Lowest Quarterly Returnrr_BarChartLowestQuarterlyReturn(0.90%)
Janus Short-Term Bond Fund | Class A, C, S, I, T Shares | Return Before Taxes | Class A
 
Average Annual Total Returnsrr_AverageAnnualReturnAbstract 
Columnrr_AverageAnnualReturnColumnNameClass A Shares
Labelrr_AverageAnnualReturnLabelReturn Before Taxes[3]
1 Yearrr_AverageAnnualReturnYear01(1.14%)
5 Yearsrr_AverageAnnualReturnYear053.89%
10 Yearsrr_AverageAnnualReturnYear103.47%
Since Inceptionrr_AverageAnnualReturnSinceInception4.13%
Inception Daterr_AverageAnnualReturnInceptionDateSep. 01, 1992
Janus Short-Term Bond Fund | Class A, C, S, I, T Shares | Return Before Taxes | Class C
 
Average Annual Total Returnsrr_AverageAnnualReturnAbstract 
Columnrr_AverageAnnualReturnColumnNameClass C Shares
Labelrr_AverageAnnualReturnLabelReturn Before Taxes[4]
1 Yearrr_AverageAnnualReturnYear011.60%
5 Yearsrr_AverageAnnualReturnYear054.28%
10 Yearsrr_AverageAnnualReturnYear103.33%
Since Inceptionrr_AverageAnnualReturnSinceInception3.72%
Inception Daterr_AverageAnnualReturnInceptionDateSep. 01, 1992
Janus Short-Term Bond Fund | Class A, C, S, I, T Shares | Return Before Taxes | Class S
 
Average Annual Total Returnsrr_AverageAnnualReturnAbstract 
Columnrr_AverageAnnualReturnColumnNameClass S Shares
Labelrr_AverageAnnualReturnLabelReturn Before Taxes
1 Yearrr_AverageAnnualReturnYear013.11%
5 Yearsrr_AverageAnnualReturnYear054.60%
10 Yearsrr_AverageAnnualReturnYear103.75%
Since Inceptionrr_AverageAnnualReturnSinceInception4.21%
Inception Daterr_AverageAnnualReturnInceptionDateSep. 01, 1992
Janus Short-Term Bond Fund | Class A, C, S, I, T Shares | Return Before Taxes | Class I
 
Average Annual Total Returnsrr_AverageAnnualReturnAbstract 
Columnrr_AverageAnnualReturnColumnNameClass I Shares
Labelrr_AverageAnnualReturnLabelReturn Before Taxes
1 Yearrr_AverageAnnualReturnYear013.96%
5 Yearsrr_AverageAnnualReturnYear055.07%
10 Yearsrr_AverageAnnualReturnYear104.18%
Since Inceptionrr_AverageAnnualReturnSinceInception4.63%
Inception Daterr_AverageAnnualReturnInceptionDateSep. 01, 1992
Janus Short-Term Bond Fund | Class A, C, S, I, T Shares | Return Before Taxes | Class T
 
Average Annual Total Returnsrr_AverageAnnualReturnAbstract 
Columnrr_AverageAnnualReturnColumnNameClass T Shares
Labelrr_AverageAnnualReturnLabelReturn Before Taxes
1 Yearrr_AverageAnnualReturnYear013.37%
5 Yearsrr_AverageAnnualReturnYear055.18%
10 Yearsrr_AverageAnnualReturnYear104.36%
Since Inceptionrr_AverageAnnualReturnSinceInception4.82%
Inception Daterr_AverageAnnualReturnInceptionDateSep. 01, 1992
Janus Short-Term Bond Fund | Class A, C, S, I, T Shares | Return After Taxes on Distributions | Class T
 
Average Annual Total Returnsrr_AverageAnnualReturnAbstract 
Columnrr_AverageAnnualReturnColumnNameClass T Shares
Labelrr_AverageAnnualReturnLabelReturn After Taxes on Distributions
1 Yearrr_AverageAnnualReturnYear012.35%
5 Yearsrr_AverageAnnualReturnYear053.86%
10 Yearsrr_AverageAnnualReturnYear103.06%
Since Inceptionrr_AverageAnnualReturnSinceInception3.05%
Inception Daterr_AverageAnnualReturnInceptionDateSep. 01, 1992
Janus Short-Term Bond Fund | Class A, C, S, I, T Shares | Return After Taxes on Distributions and Sale of Fund Shares | Class T
 
Average Annual Total Returnsrr_AverageAnnualReturnAbstract 
Columnrr_AverageAnnualReturnColumnNameClass T Shares
Labelrr_AverageAnnualReturnLabelReturn After Taxes on Distributions and Sale of Fund Shares[5]
1 Yearrr_AverageAnnualReturnYear012.23%
5 Yearsrr_AverageAnnualReturnYear053.66%
10 Yearsrr_AverageAnnualReturnYear102.96%
Since Inceptionrr_AverageAnnualReturnSinceInception3.01%
Inception Daterr_AverageAnnualReturnInceptionDateSep. 01, 1992
Janus Short-Term Bond Fund | Class A, C, S, I, T Shares | Barclays Capital 1-3 Year U.S. Government/Credit Index
 
Average Annual Total Returnsrr_AverageAnnualReturnAbstract 
Labelrr_AverageAnnualReturnLabelBarclays Capital 1-3 Year U.S. Government/Credit Index
Index No Deduction for Fees, Expenses, Taxes [Text]rr_IndexNoDeductionForFeesExpensesTaxes(reflects no deduction for expenses, fees, or taxes)
1 Yearrr_AverageAnnualReturnYear012.80%
5 Yearsrr_AverageAnnualReturnYear054.53%
10 Yearsrr_AverageAnnualReturnYear104.34%
Since Inceptionrr_AverageAnnualReturnSinceInception4.98%
Inception Daterr_AverageAnnualReturnInceptionDateSep. 01, 1992
Janus Short-Term Bond Fund | Class D Shares
 
Risk/Return:rr_RiskReturnAbstract 
Risk/Return [Heading]rr_RiskReturnHeadingFUND SUMMARY Janus Short-Term Bond Fund
Objective [Heading]rr_ObjectiveHeadingINVESTMENT OBJECTIVE
Objective, Primary [Text Block]rr_ObjectivePrimaryTextBlockJanus Short-Term Bond Fund seeks as high a level of current income as is consistent with preservation of capital.
FEES AND EXPENSES OF THE FUNDjif277751_FundFeesAndExpensesAbstract 
Expense [Heading]rr_ExpenseHeadingFEES AND EXPENSES OF THE FUND
Expense Narrative [Text Block]rr_ExpenseNarrativeTextBlockThis table describes the fees and expenses that you may pay if you buy and hold Shares of the Fund.
ANNUAL FUND OPERATING EXPENSESrr_OperatingExpensesAbstract 
Operating Expenses Caption [Text]rr_OperatingExpensesCaptionANNUAL 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 Terminationrr_FeeWaiverOrReimbursementOverAssetsDateOfTerminationNovember 1, 2012
EXAMPLE:rr_ExpenseExampleAbstract 
Expense Example [Heading]rr_ExpenseExampleHeadingEXAMPLE:
Expense Example Narrative [Text Block]rr_ExpenseExampleNarrativeTextBlockThe 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 [Heading]rr_ExpenseExampleByYearHeadingThe 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:
Portfolio Turnover:jif277751_PortfolioTurnoverAltAbstract 
Portfolio Turnover [Heading]rr_PortfolioTurnoverHeadingPortfolio Turnover:
Portfolio Turnover [Text Block]rr_PortfolioTurnoverTextBlockThe 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 period, the Fund’s portfolio turnover rate was 100% of the average value of its portfolio.
Portfolio Turnover, Raterr_PortfolioTurnoverRate100.00%
Principal Investment Strategiesjif277751_PrincipalInvestmentStrategiesAbstract 
Strategy [Heading]rr_StrategyHeadingPRINCIPAL 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. 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 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 also invest in foreign debt securities, which may include investments in emerging markets.

The Fund may invest its assets in derivatives, which are instruments that have a value derived from an underlying asset, such as equity securities, bonds, 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. For more information on the Fund’s use of derivatives, refer to the Fund’s shareholder reports and Form N-Q reports, which are filed with the Securities and Exchange Commission.

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 Risksjif277751_PrincipalInvestmentRisksAbstract 
Risk [Heading]rr_RiskHeadingPRINCIPAL 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 their value 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.

Mortgage-Backed Securities Risk. Mortgage-backed securities tend to be more sensitive to changes in interest rates than other types of 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.

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.

Foreign Exposure Risk. The Fund may have exposure to foreign markets, including 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. 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.

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 can be substantially greater than the derivative’s original cost, and can therefore involve 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_RiskLoseMoneyAlthough 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_RiskNotInsuredDepositoryInstitutionAn 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 INFORMATIONjif277751_FundPastPerformanceAbstract 
Bar Chart and Performance Table [Heading]rr_BarChartAndPerformanceTableHeadingPERFORMANCE 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_PerformanceAdditionalMarketIndexThe 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 Past Does Not Indicate Future [Text]rr_PerformancePastDoesNotIndicateFutureThe Fund’s past performance (before and after taxes) does not necessarily indicate how it will perform in the future.
Performance Table Closing [Text Block]rr_PerformanceTableClosingTextBlockUpdated performance information is available at janus.com/allfunds or by calling 1-800-525-3713.
Performance Availability Website Address [Text]rr_PerformanceAvailabilityWebSiteAddressjanus.com/allfunds
Performance Availability Phone [Text]rr_PerformanceAvailabilityPhone1-800-525-3713
Annual Total Returnsrr_BarChartTableAbstract 
Bar Chart [Heading]rr_BarChartHeadingAnnual Total Returns for Class D Shares (calendar year-end)
Bar Chart Closing [Text Block]rr_BarChartClosingTextBlockBest Quarter: Second Quarter 2009 3.18%          Worst Quarter: Second Quarter 2008 -0.90%
Year to Date Return, Labelrr_YearToDateReturnLabelThe Fund’s year-to-date return as of the calendar quarter ended September 30, 2011 was 0.71%.
Bar Chart, Year to Date Return, Daterr_BarChartYearToDateReturnDateSep. 30, 2011
Bar Chart, Year to Date Returnrr_BarChartYearToDateReturn0.71%
Average Annual Total Returnsrr_AverageAnnualReturnAbstract 
Captionrr_AverageAnnualReturnCaptionAverage Annual Total Returns (periods ended 12/31/10)
Performance Table Narrativerr_PerformanceTableNarrativeTextBlockAfter-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 Uses Highest Federal Raterr_PerformanceTableUsesHighestFederalRateAfter-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 Deferredrr_PerformanceTableNotRelevantToTaxDeferredActual 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.
Janus Short-Term Bond Fund | Class D Shares | Class D
 
ANNUAL FUND OPERATING EXPENSESrr_OperatingExpensesAbstract 
Operating Expenses Column [Text]rr_OperatingExpensesColumnNameClass D
Management Feesrr_ManagementFeesOverAssets0.55%
Other Expensesrr_OtherExpensesOverAssets0.18%
Total Annual Fund Operating Expensesrr_ExpensesOverAssets0.73%[16]
Fee Waiverrr_FeeWaiverOrReimbursementOverAssets0.05%[16]
Net Annual Fund Operating Expenses After Fee Waiverrr_NetExpensesOverAssets0.68%[16]
EXAMPLE:rr_ExpenseExampleAbstract 
Expense Example, By Year, Column [Text]rr_ExpenseExampleByYearColumnNameClass D Shares
1 Yearrr_ExpenseExampleYear0175
3 Yearsrr_ExpenseExampleYear03233
5 Yearsrr_ExpenseExampleYear05406
10 Yearsrr_ExpenseExampleYear10906
Annual Total Returnsrr_BarChartTableAbstract 
2001rr_AnnualReturn20016.85%
2002rr_AnnualReturn20023.57%
2003rr_AnnualReturn20033.91%
2004rr_AnnualReturn20041.96%
2005rr_AnnualReturn20051.52%
2006rr_AnnualReturn20064.21%
2007rr_AnnualReturn20075.21%
2008rr_AnnualReturn20084.63%
2009rr_AnnualReturn20098.56%
2010rr_AnnualReturn20103.48%
Highest Quarterly Return, Labelrr_HighestQuarterlyReturnLabelBest Quarter:
Highest Quarterly Return, Daterr_BarChartHighestQuarterlyReturnDateJun. 30, 2009
Highest Quarterly Returnrr_BarChartHighestQuarterlyReturn3.18%
Lowest Quarterly Return, Labelrr_LowestQuarterlyReturnLabelWorst Quarter:
Lowest Quarterly Return, Daterr_BarChartLowestQuarterlyReturnDateJun. 30, 2008
Lowest Quarterly Returnrr_BarChartLowestQuarterlyReturn(0.90%)
Janus Short-Term Bond Fund | Class D Shares | Return Before Taxes | Class D
 
Average Annual Total Returnsrr_AverageAnnualReturnAbstract 
Columnrr_AverageAnnualReturnColumnNameClass D Shares
Labelrr_AverageAnnualReturnLabelReturn Before Taxes
1 Yearrr_AverageAnnualReturnYear013.48%
5 Yearsrr_AverageAnnualReturnYear055.20%
10 Yearsrr_AverageAnnualReturnYear104.37%
Since Inceptionrr_AverageAnnualReturnSinceInception4.83%
Inception Daterr_AverageAnnualReturnInceptionDateSep. 01, 1992
Janus Short-Term Bond Fund | Class D Shares | Return After Taxes on Distributions | Class D
 
Average Annual Total Returnsrr_AverageAnnualReturnAbstract 
Columnrr_AverageAnnualReturnColumnNameClass D Shares
Labelrr_AverageAnnualReturnLabelReturn After Taxes on Distributions
1 Yearrr_AverageAnnualReturnYear012.41%
5 Yearsrr_AverageAnnualReturnYear053.88%
10 Yearsrr_AverageAnnualReturnYear103.06%
Since Inceptionrr_AverageAnnualReturnSinceInception3.05%
Inception Daterr_AverageAnnualReturnInceptionDateSep. 01, 1992
Janus Short-Term Bond Fund | Class D Shares | Return After Taxes on Distributions and Sale of Fund Shares | Class D
 
Average Annual Total Returnsrr_AverageAnnualReturnAbstract 
Columnrr_AverageAnnualReturnColumnNameClass D Shares
Labelrr_AverageAnnualReturnLabelReturn After Taxes on Distributions and Sale of Fund Shares[5]
1 Yearrr_AverageAnnualReturnYear012.30%
5 Yearsrr_AverageAnnualReturnYear053.67%
10 Yearsrr_AverageAnnualReturnYear102.97%
Since Inceptionrr_AverageAnnualReturnSinceInception3.02%
Inception Daterr_AverageAnnualReturnInceptionDateSep. 01, 1992
Janus Short-Term Bond Fund | Class D Shares | Barclays Capital 1-3 Year U.S. Government/Credit Index
 
Average Annual Total Returnsrr_AverageAnnualReturnAbstract 
Labelrr_AverageAnnualReturnLabelBarclays Capital 1-3 Year U.S. Government/Credit Index
Index No Deduction for Fees, Expenses, Taxes [Text]rr_IndexNoDeductionForFeesExpensesTaxes(reflects no deduction for expenses, fees, or taxes)
1 Yearrr_AverageAnnualReturnYear012.80%
5 Yearsrr_AverageAnnualReturnYear054.53%
10 Yearsrr_AverageAnnualReturnYear104.34%
Since Inceptionrr_AverageAnnualReturnSinceInception4.98%
Inception Daterr_AverageAnnualReturnInceptionDateSep. 01, 1992
INTECH International Fund | Class A, C, S, I, T Shares
 
Risk/Return:rr_RiskReturnAbstract 
Risk/Return [Heading]rr_RiskReturnHeadingFUND SUMMARY INTECH International Fund[1]
Objective [Heading]rr_ObjectiveHeadingINVESTMENT OBJECTIVE
Objective, Primary [Text Block]rr_ObjectivePrimaryTextBlockINTECH International Fund seeks long-term growth of capital.
FEES AND EXPENSES OF THE FUNDjif277751_FundFeesAndExpensesAbstract 
Expense [Heading]rr_ExpenseHeadingFEES AND EXPENSES OF THE FUND
Expense Narrative [Text Block]rr_ExpenseNarrativeTextBlockThis 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.
Expense Breakpoint Discountsjif277751_ExpenseBreakpointDiscountsAbstract 
Expense Breakpoint Discounts [Text]rr_ExpenseBreakpointDiscountsFor 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 41 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_ExpenseBreakpointMinimumInvestmentRequiredAmount50,000
SHAREHOLDER FEESrr_ShareholderFeesAbstract 
Shareholder Fees Caption [Text]rr_ShareholderFeesCaptionSHAREHOLDER FEES (fees paid directly from your investment)
ANNUAL FUND OPERATING EXPENSESrr_OperatingExpensesAbstract 
Operating Expenses Caption [Text]rr_OperatingExpensesCaptionANNUAL 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 Terminationrr_FeeWaiverOrReimbursementOverAssetsDateOfTerminationNovember 1, 2012
EXAMPLE:rr_ExpenseExampleAbstract 
Expense Example [Heading]rr_ExpenseExampleHeadingEXAMPLE:
Expense Example Narrative [Text Block]rr_ExpenseExampleNarrativeTextBlockThe 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 [Heading]rr_ExpenseExampleByYearHeadingThe 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 by, Year, Caption [Text]rr_ExpenseExampleByYearCaptionIf Shares are redeemed:
Expense Example, No Redemption:rr_ExpenseExampleNoRedemptionAbstract 
Expense Example, No Redemption, By Year, Caption [Text]rr_ExpenseExampleNoRedemptionByYearCaptionIf Shares are not redeemed:
Portfolio Turnover:jif277751_PortfolioTurnoverAltAbstract 
Portfolio Turnover [Heading]rr_PortfolioTurnoverHeadingPortfolio Turnover:
Portfolio Turnover [Text Block]rr_PortfolioTurnoverTextBlockThe 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 period, the Fund’s portfolio turnover rate was 179% of the average value of its portfolio.
Portfolio Turnover, Raterr_PortfolioTurnoverRate179.00%
Principal Investment Strategiesjif277751_PrincipalInvestmentStrategiesAbstract 
Strategy [Heading]rr_StrategyHeadingPRINCIPAL 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® 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 the Fund 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 Risksjif277751_PrincipalInvestmentRisksAbstract 
Risk [Heading]rr_RiskHeadingPRINCIPAL 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, 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. 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.

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. On a routine basis, INTECH considers 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_RiskLoseMoneyThe biggest risk is that the Fund’s returns will vary, and you could lose money.
Risk Not Insured Depository Institution [Text]rr_RiskNotInsuredDepositoryInstitutionAn 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 INFORMATIONjif277751_FundPastPerformanceAbstract 
Bar Chart and Performance Table [Heading]rr_BarChartAndPerformanceTableHeadingPERFORMANCE 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.

Bar Chart Does Not Reflect Sales Loads [Text]rr_BarChartDoesNotReflectSalesLoadsThe 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.
Performance Additional Market Index [Text]rr_PerformanceAdditionalMarketIndexThe 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 Past Does Not Indicate Future [Text]rr_PerformancePastDoesNotIndicateFutureThe Fund’s past performance (before and after taxes) does not necessarily indicate how it will perform in the future.
Performance Table Closing [Text Block]rr_PerformanceTableClosingTextBlockUpdated performance information is available at janus.com/advisor/mutual-funds or by calling 1-877-335-2687.
Performance Availability Website Address [Text]rr_PerformanceAvailabilityWebSiteAddress janus.com/advisor/mutual-funds
Performance Availability Phone [Text]rr_PerformanceAvailabilityPhone1-877-335-2687
Annual Total Returnsrr_BarChartTableAbstract 
Bar Chart [Heading]rr_BarChartHeadingAnnual Total Returns for Class I Shares (calendar year-end)
Bar Chart Closing [Text Block]rr_BarChartClosingTextBlockBest Quarter: Second Quarter 2009 22.50%            Worst Quarter: Third Quarter 2008 -20.70%
Year to Date Return, Labelrr_YearToDateReturnLabelThe Fund’s year-to-date return as of the calendar quarter ended September 30, 2011 was -16.93%.
Bar Chart, Year to Date Return, Daterr_BarChartYearToDateReturnDateSep. 30, 2011
Bar Chart, Year to Date Returnrr_BarChartYearToDateReturn(16.93%)
Average Annual Total Returnsrr_AverageAnnualReturnAbstract 
Captionrr_AverageAnnualReturnCaptionAverage Annual Total Returns (periods ended 12/31/10)
Performance Table Narrativerr_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 Uses Highest Federal Raterr_PerformanceTableUsesHighestFederalRateAfter-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 Deferredrr_PerformanceTableNotRelevantToTaxDeferredActual 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_PerformanceTableOneClassOfAfterTaxShownAfter-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.
INTECH International Fund | Class A, C, S, I, T Shares | Class A
 
SHAREHOLDER FEESrr_ShareholderFeesAbstract 
Shareholder Fees Column [Text]rr_ShareholderFeesColumnNameClass A
Maximum Sales Charge (load) Imposed on Purchases (as a percentage of offering price)rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice5.75%
Maximum Deferred Sales Charge (load) (as a percentage of the lower of original purchase price or redemption proceeds)rr_MaximumDeferredSalesChargeOverOther none
Redemption fee on Shares held for 90 days or less (as a percentage of amount redeemed)rr_RedemptionFeeOverRedemption none
ANNUAL FUND OPERATING EXPENSESrr_OperatingExpensesAbstract 
Operating Expenses Column [Text]rr_OperatingExpensesColumnNameClass A
Management Feesrr_ManagementFeesOverAssets0.55%
Distribution/Service (12b-1) Feesrr_DistributionAndService12b1FeesOverAssets0.25%
Other Expensesrr_OtherExpensesOverAssets2.43%
Total Annual Fund Operating Expensesrr_ExpensesOverAssets3.23%[22]
Fee Waiverrr_FeeWaiverOrReimbursementOverAssets1.91%[22]
Net Annual Fund Operating Expenses After Fee Waiverrr_NetExpensesOverAssets1.32%[22]
EXAMPLE:rr_ExpenseExampleAbstract 
Expense Example, By Year, Column [Text]rr_ExpenseExampleByYearColumnNameClass A Shares
1 Yearrr_ExpenseExampleYear01882
3 Yearsrr_ExpenseExampleYear031,513
5 Yearsrr_ExpenseExampleYear052,166
10 Yearsrr_ExpenseExampleYear103,903
Expense Example, No Redemption:rr_ExpenseExampleNoRedemptionAbstract 
Expense Example, No Redemption, By Year, Column [Text]rr_ExpenseExampleNoRedemptionByYearColumnNameClass A Shares
1 Yearrr_ExpenseExampleNoRedemptionYear01882
3 Yearsrr_ExpenseExampleNoRedemptionYear031,513
5 Yearsrr_ExpenseExampleNoRedemptionYear052,166
10 Yearsrr_ExpenseExampleNoRedemptionYear103,903
INTECH International Fund | Class A, C, S, I, T Shares | Class C
 
SHAREHOLDER FEESrr_ShareholderFeesAbstract 
Shareholder Fees Column [Text]rr_ShareholderFeesColumnNameClass 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_MaximumDeferredSalesChargeOverOther1.00%
Redemption fee on Shares held for 90 days or less (as a percentage of amount redeemed)rr_RedemptionFeeOverRedemption none
ANNUAL FUND OPERATING EXPENSESrr_OperatingExpensesAbstract 
Operating Expenses Column [Text]rr_OperatingExpensesColumnNameClass C
Management Feesrr_ManagementFeesOverAssets0.55%
Distribution/Service (12b-1) Feesrr_DistributionAndService12b1FeesOverAssets1.00%
Other Expensesrr_OtherExpensesOverAssets2.42%
Total Annual Fund Operating Expensesrr_ExpensesOverAssets3.97%[22]
Fee Waiverrr_FeeWaiverOrReimbursementOverAssets1.90%[22]
Net Annual Fund Operating Expenses After Fee Waiverrr_NetExpensesOverAssets2.07%[22]
EXAMPLE:rr_ExpenseExampleAbstract 
Expense Example, By Year, Column [Text]rr_ExpenseExampleByYearColumnNameClass C Shares
1 Yearrr_ExpenseExampleYear01499
3 Yearsrr_ExpenseExampleYear031,210
5 Yearsrr_ExpenseExampleYear052,037
10 Yearsrr_ExpenseExampleYear104,181
Expense Example, No Redemption:rr_ExpenseExampleNoRedemptionAbstract 
Expense Example, No Redemption, By Year, Column [Text]rr_ExpenseExampleNoRedemptionByYearColumnNameClass C Shares
1 Yearrr_ExpenseExampleNoRedemptionYear01399
3 Yearsrr_ExpenseExampleNoRedemptionYear031,210
5 Yearsrr_ExpenseExampleNoRedemptionYear052,037
10 Yearsrr_ExpenseExampleNoRedemptionYear104,181
INTECH International Fund | Class A, C, S, I, T Shares | Class S
 
SHAREHOLDER FEESrr_ShareholderFeesAbstract 
Shareholder Fees Column [Text]rr_ShareholderFeesColumnNameClass 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
Redemption fee on Shares held for 90 days or less (as a percentage of amount redeemed)rr_RedemptionFeeOverRedemption2.00%
ANNUAL FUND OPERATING EXPENSESrr_OperatingExpensesAbstract 
Operating Expenses Column [Text]rr_OperatingExpensesColumnNameClass S
Management Feesrr_ManagementFeesOverAssets0.55%
Distribution/Service (12b-1) Feesrr_DistributionAndService12b1FeesOverAssets0.25%
Other Expensesrr_OtherExpensesOverAssets2.67%
Total Annual Fund Operating Expensesrr_ExpensesOverAssets3.47%[22]
Fee Waiverrr_FeeWaiverOrReimbursementOverAssets1.89%[22]
Net Annual Fund Operating Expenses After Fee Waiverrr_NetExpensesOverAssets1.58%[22]
EXAMPLE:rr_ExpenseExampleAbstract 
Expense Example, By Year, Column [Text]rr_ExpenseExampleByYearColumnNameClass S Shares
1 Yearrr_ExpenseExampleYear01350
3 Yearsrr_ExpenseExampleYear031,065
5 Yearsrr_ExpenseExampleYear051,803
10 Yearsrr_ExpenseExampleYear103,747
Expense Example, No Redemption:rr_ExpenseExampleNoRedemptionAbstract 
Expense Example, No Redemption, By Year, Column [Text]rr_ExpenseExampleNoRedemptionByYearColumnNameClass S Shares
1 Yearrr_ExpenseExampleNoRedemptionYear01350
3 Yearsrr_ExpenseExampleNoRedemptionYear031,065
5 Yearsrr_ExpenseExampleNoRedemptionYear051,803
10 Yearsrr_ExpenseExampleNoRedemptionYear103,747
INTECH International Fund | Class A, C, S, I, T Shares | Class I
 
SHAREHOLDER FEESrr_ShareholderFeesAbstract 
Shareholder Fees Column [Text]rr_ShareholderFeesColumnNameClass 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
Redemption fee on Shares held for 90 days or less (as a percentage of amount redeemed)rr_RedemptionFeeOverRedemption2.00%
ANNUAL FUND OPERATING EXPENSESrr_OperatingExpensesAbstract 
Operating Expenses Column [Text]rr_OperatingExpensesColumnNameClass I
Management Feesrr_ManagementFeesOverAssets0.55%
Distribution/Service (12b-1) Feesrr_DistributionAndService12b1FeesOverAssets none
Other Expensesrr_OtherExpensesOverAssets2.54%
Total Annual Fund Operating Expensesrr_ExpensesOverAssets3.09%[22]
Fee Waiverrr_FeeWaiverOrReimbursementOverAssets2.02%[22]
Net Annual Fund Operating Expenses After Fee Waiverrr_NetExpensesOverAssets1.07%[22]
EXAMPLE:rr_ExpenseExampleAbstract 
Expense Example, By Year, Column [Text]rr_ExpenseExampleByYearColumnNameClass I Shares
1 Yearrr_ExpenseExampleYear01312
3 Yearsrr_ExpenseExampleYear03954
5 Yearsrr_ExpenseExampleYear051,620
10 Yearsrr_ExpenseExampleYear103,402
Expense Example, No Redemption:rr_ExpenseExampleNoRedemptionAbstract 
Expense Example, No Redemption, By Year, Column [Text]rr_ExpenseExampleNoRedemptionByYearColumnNameClass I Shares
1 Yearrr_ExpenseExampleNoRedemptionYear01312
3 Yearsrr_ExpenseExampleNoRedemptionYear03954
5 Yearsrr_ExpenseExampleNoRedemptionYear051,620
10 Yearsrr_ExpenseExampleNoRedemptionYear103,402
Annual Total Returnsrr_BarChartTableAbstract 
2008rr_AnnualReturn2008(41.75%)
2009rr_AnnualReturn200925.53%
2010rr_AnnualReturn20109.76%
Highest Quarterly Return, Labelrr_HighestQuarterlyReturnLabelBest Quarter:
Highest Quarterly Return, Daterr_BarChartHighestQuarterlyReturnDateJun. 30, 2009
Highest Quarterly Returnrr_BarChartHighestQuarterlyReturn22.50%
Lowest Quarterly Return, Labelrr_LowestQuarterlyReturnLabelWorst Quarter:
Lowest Quarterly Return, Daterr_BarChartLowestQuarterlyReturnDateSep. 30, 2008
Lowest Quarterly Returnrr_BarChartLowestQuarterlyReturn(20.70%)
INTECH International Fund | Class A, C, S, I, T Shares | Class T
 
SHAREHOLDER FEESrr_ShareholderFeesAbstract 
Shareholder Fees Column [Text]rr_ShareholderFeesColumnNameClass 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
Redemption fee on Shares held for 90 days or less (as a percentage of amount redeemed)rr_RedemptionFeeOverRedemption2.00%
ANNUAL FUND OPERATING EXPENSESrr_OperatingExpensesAbstract 
Operating Expenses Column [Text]rr_OperatingExpensesColumnNameClass T
Management Feesrr_ManagementFeesOverAssets0.55%
Distribution/Service (12b-1) Feesrr_DistributionAndService12b1FeesOverAssets none
Other Expensesrr_OtherExpensesOverAssets2.67%
Total Annual Fund Operating Expensesrr_ExpensesOverAssets3.22%[22]
Fee Waiverrr_FeeWaiverOrReimbursementOverAssets1.90%[22]
Net Annual Fund Operating Expenses After Fee Waiverrr_NetExpensesOverAssets1.32%[22]
EXAMPLE:rr_ExpenseExampleAbstract 
Expense Example, By Year, Column [Text]rr_ExpenseExampleByYearColumnNameClass T Shares
1 Yearrr_ExpenseExampleYear01325
3 Yearsrr_ExpenseExampleYear03992
5 Yearsrr_ExpenseExampleYear051,683
10 Yearsrr_ExpenseExampleYear103,522
Expense Example, No Redemption:rr_ExpenseExampleNoRedemptionAbstract 
Expense Example, No Redemption, By Year, Column [Text]rr_ExpenseExampleNoRedemptionByYearColumnNameClass T Shares
1 Yearrr_ExpenseExampleNoRedemptionYear01325
3 Yearsrr_ExpenseExampleNoRedemptionYear03992
5 Yearsrr_ExpenseExampleNoRedemptionYear051,683
10 Yearsrr_ExpenseExampleNoRedemptionYear103,522
INTECH International Fund | Class A, C, S, I, T Shares | Return Before Taxes | Class A
 
Average Annual Total Returnsrr_AverageAnnualReturnAbstract 
Columnrr_AverageAnnualReturnColumnNameClass A Shares
Labelrr_AverageAnnualReturnLabelReturn Before Taxes[3]
1 Yearrr_AverageAnnualReturnYear013.75%
Since Inceptionrr_AverageAnnualReturnSinceInception(6.30%)
Inception Daterr_AverageAnnualReturnInceptionDateMay 02, 2007
INTECH International Fund | Class A, C, S, I, T Shares | Return Before Taxes | Class C
 
Average Annual Total Returnsrr_AverageAnnualReturnAbstract 
Columnrr_AverageAnnualReturnColumnNameClass C Shares
Labelrr_AverageAnnualReturnLabelReturn Before Taxes[4]
1 Yearrr_AverageAnnualReturnYear018.80%
Since Inceptionrr_AverageAnnualReturnSinceInception(5.09%)
Inception Daterr_AverageAnnualReturnInceptionDateMay 02, 2007
INTECH International Fund | Class A, C, S, I, T Shares | Return Before Taxes | Class S
 
Average Annual Total Returnsrr_AverageAnnualReturnAbstract 
Columnrr_AverageAnnualReturnColumnNameClass S Shares
Labelrr_AverageAnnualReturnLabelReturn Before Taxes
1 Yearrr_AverageAnnualReturnYear019.88%
Since Inceptionrr_AverageAnnualReturnSinceInception(4.88%)
Inception Daterr_AverageAnnualReturnInceptionDateMay 02, 2007
INTECH International Fund | Class A, C, S, I, T Shares | Return Before Taxes | Class I
 
Average Annual Total Returnsrr_AverageAnnualReturnAbstract 
Columnrr_AverageAnnualReturnColumnNameClass I Shares
Labelrr_AverageAnnualReturnLabelReturn Before Taxes
1 Yearrr_AverageAnnualReturnYear019.76%
Since Inceptionrr_AverageAnnualReturnSinceInception(4.74%)
Inception Daterr_AverageAnnualReturnInceptionDateMay 02, 2007
INTECH International Fund | Class A, C, S, I, T Shares | Return Before Taxes | Class T
 
Average Annual Total Returnsrr_AverageAnnualReturnAbstract 
Columnrr_AverageAnnualReturnColumnNameClass T Shares
Labelrr_AverageAnnualReturnLabelReturn Before Taxes
1 Yearrr_AverageAnnualReturnYear0110.05%
Since Inceptionrr_AverageAnnualReturnSinceInception(6.63%)
Inception Daterr_AverageAnnualReturnInceptionDateMay 02, 2007
INTECH International Fund | Class A, C, S, I, T Shares | Return After Taxes on Distributions | Class I
 
Average Annual Total Returnsrr_AverageAnnualReturnAbstract 
Columnrr_AverageAnnualReturnColumnNameClass I Shares
Labelrr_AverageAnnualReturnLabelReturn After Taxes on Distributions
1 Yearrr_AverageAnnualReturnYear019.72%
Since Inceptionrr_AverageAnnualReturnSinceInception(4.88%)
Inception Daterr_AverageAnnualReturnInceptionDateMay 02, 2007
INTECH International Fund | Class A, C, S, I, T Shares | Return After Taxes on Distributions and Sale of Fund Shares | Class I
 
Average Annual Total Returnsrr_AverageAnnualReturnAbstract 
Columnrr_AverageAnnualReturnColumnNameClass I Shares
Labelrr_AverageAnnualReturnLabelReturn After Taxes on Distributions and Sale of Fund Shares[5]
1 Yearrr_AverageAnnualReturnYear016.85%
Since Inceptionrr_AverageAnnualReturnSinceInception(3.84%)
Inception Daterr_AverageAnnualReturnInceptionDateMay 02, 2007
INTECH International Fund | Class A, C, S, I, T Shares | Morgan Stanley Capital International ("MSCI") EAFE® (Europe, Australasia, Far East) Index (net)
 
Average Annual Total Returnsrr_AverageAnnualReturnAbstract 
Labelrr_AverageAnnualReturnLabelMorgan Stanley Capital International (“MSCI”) EAFE® (Europe, Australasia, Far East) Index (net)
Index No Deduction for Fees, Expenses, Taxes [Text]rr_IndexNoDeductionForFeesExpensesTaxes(reflects no deduction for expenses, fees, or taxes)
1 Yearrr_AverageAnnualReturnYear017.75%
Since Inceptionrr_AverageAnnualReturnSinceInception(5.21%)
Inception Daterr_AverageAnnualReturnInceptionDateMay 02, 2007
INTECH U.S. Core Fund | Class A, C, S, I, T Shares
 
Risk/Return:rr_RiskReturnAbstract 
Risk/Return [Heading]rr_RiskReturnHeadingFUND SUMMARY INTECH U.S. Core Fund[1]
Objective [Heading]rr_ObjectiveHeadingINVESTMENT OBJECTIVE
Objective, Primary [Text Block]rr_ObjectivePrimaryTextBlockINTECH U.S. Core Fund seeks long-term growth of capital.
FEES AND EXPENSES OF THE FUNDjif277751_FundFeesAndExpensesAbstract 
Expense [Heading]rr_ExpenseHeadingFEES AND EXPENSES OF THE FUND
Expense Narrative [Text Block]rr_ExpenseNarrativeTextBlockThis 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.
Expense Breakpoint Discountsjif277751_ExpenseBreakpointDiscountsAbstract 
Expense Breakpoint Discounts [Text]rr_ExpenseBreakpointDiscountsFor 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 41 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_ExpenseBreakpointMinimumInvestmentRequiredAmount50,000
SHAREHOLDER FEESrr_ShareholderFeesAbstract 
Shareholder Fees Caption [Text]rr_ShareholderFeesCaptionSHAREHOLDER FEES (fees paid directly from your investment)
ANNUAL FUND OPERATING EXPENSESrr_OperatingExpensesAbstract 
Operating Expenses Caption [Text]rr_OperatingExpensesCaptionANNUAL 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 Terminationrr_FeeWaiverOrReimbursementOverAssetsDateOfTerminationNovember 1, 2012
EXAMPLE:rr_ExpenseExampleAbstract 
Expense Example [Heading]rr_ExpenseExampleHeadingEXAMPLE:
Expense Example Narrative [Text Block]rr_ExpenseExampleNarrativeTextBlockThe 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 [Heading]rr_ExpenseExampleByYearHeadingThe 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 by, Year, Caption [Text]rr_ExpenseExampleByYearCaptionIf Shares are redeemed:
Expense Example, No Redemption:rr_ExpenseExampleNoRedemptionAbstract 
Expense Example, No Redemption, By Year, Caption [Text]rr_ExpenseExampleNoRedemptionByYearCaptionIf Shares are not redeemed:
Portfolio Turnover:jif277751_PortfolioTurnoverAltAbstract 
Portfolio Turnover [Heading]rr_PortfolioTurnoverHeadingPortfolio Turnover:
Portfolio Turnover [Text Block]rr_PortfolioTurnoverTextBlockThe 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 period, the Fund’s portfolio turnover rate was 93% of the average value of its portfolio.
Portfolio Turnover, Raterr_PortfolioTurnoverRate93.00%
Principal Investment Strategiesjif277751_PrincipalInvestmentStrategiesAbstract 
Strategy [Heading]rr_StrategyHeadingPRINCIPAL 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 the Fund 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.

[1]
Principal Investment Risksjif277751_PrincipalInvestmentRisksAbstract 
Risk [Heading]rr_RiskHeadingPRINCIPAL 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. On a routine basis, INTECH considers 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_RiskLoseMoneyThe biggest risk is that the Fund’s returns will vary, and you could lose money.
Risk Not Insured Depository Institution [Text]rr_RiskNotInsuredDepositoryInstitutionAn 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 INFORMATIONjif277751_FundPastPerformanceAbstract 
Bar Chart and Performance Table [Heading]rr_BarChartAndPerformanceTableHeadingPERFORMANCE 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, 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. 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.

Bar Chart Does Not Reflect Sales Loads [Text]rr_BarChartDoesNotReflectSalesLoadsThe 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.
Performance Additional Market Index [Text]rr_PerformanceAdditionalMarketIndexThe 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 Past Does Not Indicate Future [Text]rr_PerformancePastDoesNotIndicateFutureThe Fund’s past performance (before and after taxes) does not necessarily indicate how it will perform in the future.
Performance Table Closing [Text Block]rr_PerformanceTableClosingTextBlockUpdated performance information is available at janus.com/advisor/mutual-funds or by calling 1-877-335-2687.
Performance Availability Website Address [Text]rr_PerformanceAvailabilityWebSiteAddressjanus.com/advisor/mutual-funds
Performance Availability Phone [Text]rr_PerformanceAvailabilityPhone1-877-335-2687
Annual Total Returnsrr_BarChartTableAbstract 
Bar Chart [Heading]rr_BarChartHeadingAnnual Total Returns for Class T Shares (calendar year-end)
Bar Chart Closing [Text Block]rr_BarChartClosingTextBlockBest Quarter:  Second Quarter 2009  14.79%           Worst Quarter:  Fourth Quarter 2008  -21.49%
Year to Date Return, Labelrr_YearToDateReturnLabelThe Fund’s year-to-date return as of the calendar quarter ended September 30, 2011 was -6.39%.
Bar Chart, Year to Date Return, Daterr_BarChartYearToDateReturnDateSep. 30, 2011
Bar Chart, Year to Date Returnrr_BarChartYearToDateReturn(6.39%)
Average Annual Total Returnsrr_AverageAnnualReturnAbstract 
Captionrr_AverageAnnualReturnCaptionAverage Annual Total Returns (periods ended 12/31/10)
Performance Table Narrativerr_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 Uses Highest Federal Raterr_PerformanceTableUsesHighestFederalRateAfter-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 Deferredrr_PerformanceTableNotRelevantToTaxDeferredActual 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_PerformanceTableOneClassOfAfterTaxShownAfter-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.
INTECH U.S. Core Fund | Class A, C, S, I, T Shares | Class A
 
SHAREHOLDER FEESrr_ShareholderFeesAbstract 
Shareholder Fees Column [Text]rr_ShareholderFeesColumnNameClass A
Maximum Sales Charge (load) Imposed on Purchases (as a percentage of offering price)rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice5.75%
Maximum Deferred Sales Charge (load) (as a percentage of the lower of original purchase price or redemption proceeds)rr_MaximumDeferredSalesChargeOverOther none
Redemption fee on Shares held for 90 days or less (as a percentage of amount redeemed)rr_RedemptionFeeOverRedemption none
ANNUAL FUND OPERATING EXPENSESrr_OperatingExpensesAbstract 
Operating Expenses Column [Text]rr_OperatingExpensesColumnNameClass A
Management Feesrr_ManagementFeesOverAssets0.52%
Distribution/Service (12b-1) Feesrr_DistributionAndService12b1FeesOverAssets0.25%
Other Expensesrr_OtherExpensesOverAssets0.22%
Total Annual Fund Operating Expensesrr_ExpensesOverAssets0.99%[23]
EXAMPLE:rr_ExpenseExampleAbstract 
Expense Example, By Year, Column [Text]rr_ExpenseExampleByYearColumnNameClass A Shares
1 Yearrr_ExpenseExampleYear01670
3 Yearsrr_ExpenseExampleYear03872
5 Yearsrr_ExpenseExampleYear051,091
10 Yearsrr_ExpenseExampleYear101,718
Expense Example, No Redemption:rr_ExpenseExampleNoRedemptionAbstract 
Expense Example, No Redemption, By Year, Column [Text]rr_ExpenseExampleNoRedemptionByYearColumnNameClass A Shares
1 Yearrr_ExpenseExampleNoRedemptionYear01670
3 Yearsrr_ExpenseExampleNoRedemptionYear03872
5 Yearsrr_ExpenseExampleNoRedemptionYear051,091
10 Yearsrr_ExpenseExampleNoRedemptionYear101,718
INTECH U.S. Core Fund | Class A, C, S, I, T Shares | Class C
 
SHAREHOLDER FEESrr_ShareholderFeesAbstract 
Shareholder Fees Column [Text]rr_ShareholderFeesColumnNameClass 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_MaximumDeferredSalesChargeOverOther1.00%
Redemption fee on Shares held for 90 days or less (as a percentage of amount redeemed)rr_RedemptionFeeOverRedemption none
ANNUAL FUND OPERATING EXPENSESrr_OperatingExpensesAbstract 
Operating Expenses Column [Text]rr_OperatingExpensesColumnNameClass C
Management Feesrr_ManagementFeesOverAssets0.52%
Distribution/Service (12b-1) Feesrr_DistributionAndService12b1FeesOverAssets1.00%
Other Expensesrr_OtherExpensesOverAssets0.29%
Total Annual Fund Operating Expensesrr_ExpensesOverAssets1.81%[23]
EXAMPLE:rr_ExpenseExampleAbstract 
Expense Example, By Year, Column [Text]rr_ExpenseExampleByYearColumnNameClass C Shares
1 Yearrr_ExpenseExampleYear01284
3 Yearsrr_ExpenseExampleYear03569
5 Yearsrr_ExpenseExampleYear05980
10 Yearsrr_ExpenseExampleYear102,127
Expense Example, No Redemption:rr_ExpenseExampleNoRedemptionAbstract 
Expense Example, No Redemption, By Year, Column [Text]rr_ExpenseExampleNoRedemptionByYearColumnNameClass C Shares
1 Yearrr_ExpenseExampleNoRedemptionYear01184
3 Yearsrr_ExpenseExampleNoRedemptionYear03569
5 Yearsrr_ExpenseExampleNoRedemptionYear05980
10 Yearsrr_ExpenseExampleNoRedemptionYear102,127
INTECH U.S. Core Fund | Class A, C, S, I, T Shares | Class S
 
SHAREHOLDER FEESrr_ShareholderFeesAbstract 
Shareholder Fees Column [Text]rr_ShareholderFeesColumnNameClass 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
Redemption fee on Shares held for 90 days or less (as a percentage of amount redeemed)rr_RedemptionFeeOverRedemption2.00%
ANNUAL FUND OPERATING EXPENSESrr_OperatingExpensesAbstract 
Operating Expenses Column [Text]rr_OperatingExpensesColumnNameClass S
Management Feesrr_ManagementFeesOverAssets0.52%
Distribution/Service (12b-1) Feesrr_DistributionAndService12b1FeesOverAssets0.25%
Other Expensesrr_OtherExpensesOverAssets0.42%
Total Annual Fund Operating Expensesrr_ExpensesOverAssets1.19%[23]
EXAMPLE:rr_ExpenseExampleAbstract 
Expense Example, By Year, Column [Text]rr_ExpenseExampleByYearColumnNameClass S Shares
1 Yearrr_ExpenseExampleYear01121
3 Yearsrr_ExpenseExampleYear03378
5 Yearsrr_ExpenseExampleYear05654
10 Yearsrr_ExpenseExampleYear101,443
Expense Example, No Redemption:rr_ExpenseExampleNoRedemptionAbstract 
Expense Example, No Redemption, By Year, Column [Text]rr_ExpenseExampleNoRedemptionByYearColumnNameClass S Shares
1 Yearrr_ExpenseExampleNoRedemptionYear01121
3 Yearsrr_ExpenseExampleNoRedemptionYear03378
5 Yearsrr_ExpenseExampleNoRedemptionYear05654
10 Yearsrr_ExpenseExampleNoRedemptionYear101,443
INTECH U.S. Core Fund | Class A, C, S, I, T Shares | Class I
 
SHAREHOLDER FEESrr_ShareholderFeesAbstract 
Shareholder Fees Column [Text]rr_ShareholderFeesColumnNameClass 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
Redemption fee on Shares held for 90 days or less (as a percentage of amount redeemed)rr_RedemptionFeeOverRedemption2.00%
ANNUAL FUND OPERATING EXPENSESrr_OperatingExpensesAbstract 
Operating Expenses Column [Text]rr_OperatingExpensesColumnNameClass I
Management Feesrr_ManagementFeesOverAssets0.52%
Distribution/Service (12b-1) Feesrr_DistributionAndService12b1FeesOverAssets none
Other Expensesrr_OtherExpensesOverAssets0.21%
Total Annual Fund Operating Expensesrr_ExpensesOverAssets0.73%[23]
EXAMPLE:rr_ExpenseExampleAbstract 
Expense Example, By Year, Column [Text]rr_ExpenseExampleByYearColumnNameClass I Shares
1 Yearrr_ExpenseExampleYear0175
3 Yearsrr_ExpenseExampleYear03233
5 Yearsrr_ExpenseExampleYear05406
10 Yearsrr_ExpenseExampleYear10906
Expense Example, No Redemption:rr_ExpenseExampleNoRedemptionAbstract 
Expense Example, No Redemption, By Year, Column [Text]rr_ExpenseExampleNoRedemptionByYearColumnNameClass I Shares
1 Yearrr_ExpenseExampleNoRedemptionYear0175
3 Yearsrr_ExpenseExampleNoRedemptionYear03233
5 Yearsrr_ExpenseExampleNoRedemptionYear05406
10 Yearsrr_ExpenseExampleNoRedemptionYear10906
INTECH U.S. Core Fund | Class A, C, S, I, T Shares | Class T
 
SHAREHOLDER FEESrr_ShareholderFeesAbstract 
Shareholder Fees Column [Text]rr_ShareholderFeesColumnNameClass 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
Redemption fee on Shares held for 90 days or less (as a percentage of amount redeemed)rr_RedemptionFeeOverRedemption2.00%
ANNUAL FUND OPERATING EXPENSESrr_OperatingExpensesAbstract 
Operating Expenses Column [Text]rr_OperatingExpensesColumnNameClass T
Management Feesrr_ManagementFeesOverAssets0.52%
Distribution/Service (12b-1) Feesrr_DistributionAndService12b1FeesOverAssets none
Other Expensesrr_OtherExpensesOverAssets0.41%
Total Annual Fund Operating Expensesrr_ExpensesOverAssets0.93%[23]
EXAMPLE:rr_ExpenseExampleAbstract 
Expense Example, By Year, Column [Text]rr_ExpenseExampleByYearColumnNameClass T Shares
1 Yearrr_ExpenseExampleYear0195
3 Yearsrr_ExpenseExampleYear03296
5 Yearsrr_ExpenseExampleYear05515
10 Yearsrr_ExpenseExampleYear101,143
Expense Example, No Redemption:rr_ExpenseExampleNoRedemptionAbstract 
Expense Example, No Redemption, By Year, Column [Text]rr_ExpenseExampleNoRedemptionByYearColumnNameClass T Shares
1 Yearrr_ExpenseExampleNoRedemptionYear0195
3 Yearsrr_ExpenseExampleNoRedemptionYear03296
5 Yearsrr_ExpenseExampleNoRedemptionYear05515
10 Yearsrr_ExpenseExampleNoRedemptionYear101,143
Annual Total Returnsrr_BarChartTableAbstract 
2004rr_AnnualReturn200417.68%
2005rr_AnnualReturn200511.06%
2006rr_AnnualReturn200611.37%
2007rr_AnnualReturn20076.40%
2008rr_AnnualReturn2008(36.57%)
2009rr_AnnualReturn200922.91%
2010rr_AnnualReturn201016.28%
Highest Quarterly Return, Labelrr_HighestQuarterlyReturnLabelBest Quarter:
Highest Quarterly Return, Daterr_BarChartHighestQuarterlyReturnDateJun. 30, 2009
Highest Quarterly Returnrr_BarChartHighestQuarterlyReturn14.79%
Lowest Quarterly Return, Labelrr_LowestQuarterlyReturnLabelWorst Quarter:
Lowest Quarterly Return, Daterr_BarChartLowestQuarterlyReturnDateDec. 31, 2008
Lowest Quarterly Returnrr_BarChartLowestQuarterlyReturn(21.49%)
INTECH U.S. Core Fund | Class A, C, S, I, T Shares | Return Before Taxes | Class A
 
Average Annual Total Returnsrr_AverageAnnualReturnAbstract 
Columnrr_AverageAnnualReturnColumnNameClass A Shares
Labelrr_AverageAnnualReturnLabelReturn Before Taxes[3]
1 Yearrr_AverageAnnualReturnYear019.36%
5 Yearsrr_AverageAnnualReturnYear05(0.02%)
Since Inceptionrr_AverageAnnualReturnSinceInception7.03%
Inception Daterr_AverageAnnualReturnInceptionDateFeb. 28, 2003
INTECH U.S. Core Fund | Class A, C, S, I, T Shares | Return Before Taxes | Class C
 
Average Annual Total Returnsrr_AverageAnnualReturnAbstract 
Columnrr_AverageAnnualReturnColumnNameClass C Shares
Labelrr_AverageAnnualReturnLabelReturn Before Taxes[4]
1 Yearrr_AverageAnnualReturnYear0114.19%
5 Yearsrr_AverageAnnualReturnYear050.44%
Since Inceptionrr_AverageAnnualReturnSinceInception7.06%
Inception Daterr_AverageAnnualReturnInceptionDateFeb. 28, 2003
INTECH U.S. Core Fund | Class A, C, S, I, T Shares | Return Before Taxes | Class S
 
Average Annual Total Returnsrr_AverageAnnualReturnAbstract 
Columnrr_AverageAnnualReturnColumnNameClass S Shares
Labelrr_AverageAnnualReturnLabelReturn Before Taxes
1 Yearrr_AverageAnnualReturnYear0116.07%
5 Yearsrr_AverageAnnualReturnYear051.00%
Since Inceptionrr_AverageAnnualReturnSinceInception7.65%
Inception Daterr_AverageAnnualReturnInceptionDateFeb. 28, 2003
INTECH U.S. Core Fund | Class A, C, S, I, T Shares | Return Before Taxes | Class I
 
Average Annual Total Returnsrr_AverageAnnualReturnAbstract 
Columnrr_AverageAnnualReturnColumnNameClass I Shares
Labelrr_AverageAnnualReturnLabelReturn Before Taxes
1 Yearrr_AverageAnnualReturnYear0116.59%
5 Yearsrr_AverageAnnualReturnYear051.44%
Since Inceptionrr_AverageAnnualReturnSinceInception8.16%
Inception Daterr_AverageAnnualReturnInceptionDateFeb. 28, 2003
INTECH U.S. Core Fund | Class A, C, S, I, T Shares | Return Before Taxes | Class T
 
Average Annual Total Returnsrr_AverageAnnualReturnAbstract 
Columnrr_AverageAnnualReturnColumnNameClass T Shares
Labelrr_AverageAnnualReturnLabelReturn Before Taxes
1 Yearrr_AverageAnnualReturnYear0116.28%
5 Yearsrr_AverageAnnualReturnYear051.44%
Since Inceptionrr_AverageAnnualReturnSinceInception8.16%
Inception Daterr_AverageAnnualReturnInceptionDateFeb. 28, 2003
INTECH U.S. Core Fund | Class A, C, S, I, T Shares | Return After Taxes on Distributions | Class T
 
Average Annual Total Returnsrr_AverageAnnualReturnAbstract 
Columnrr_AverageAnnualReturnColumnNameClass T Shares
Labelrr_AverageAnnualReturnLabelReturn After Taxes on Distributions
1 Yearrr_AverageAnnualReturnYear0116.11%
5 Yearsrr_AverageAnnualReturnYear050.81%
Since Inceptionrr_AverageAnnualReturnSinceInception7.35%
Inception Daterr_AverageAnnualReturnInceptionDateFeb. 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
 
Average Annual Total Returnsrr_AverageAnnualReturnAbstract 
Columnrr_AverageAnnualReturnColumnNameClass T Shares
Labelrr_AverageAnnualReturnLabelReturn After Taxes on Distributions and Sale of Fund Shares[5]
1 Yearrr_AverageAnnualReturnYear0110.80%
5 Yearsrr_AverageAnnualReturnYear051.23%
Since Inceptionrr_AverageAnnualReturnSinceInception7.03%
Inception Daterr_AverageAnnualReturnInceptionDateFeb. 28, 2003
INTECH U.S. Core Fund | Class A, C, S, I, T Shares | S&P 500® Index
 
Average Annual Total Returnsrr_AverageAnnualReturnAbstract 
Labelrr_AverageAnnualReturnLabelS&P 500® Index
Index No Deduction for Fees, Expenses, Taxes [Text]rr_IndexNoDeductionForFeesExpensesTaxes(reflects no deduction for expenses, fees, or taxes)
1 Yearrr_AverageAnnualReturnYear0115.06%
5 Yearsrr_AverageAnnualReturnYear052.29%
Since Inceptionrr_AverageAnnualReturnSinceInception7.38%
Inception Daterr_AverageAnnualReturnInceptionDateFeb. 28, 2003
INTECH U.S. Core Fund | Class D Shares
 
Risk/Return:rr_RiskReturnAbstract 
Risk/Return [Heading]rr_RiskReturnHeadingFUND SUMMARY INTECH U.S. Core Fund[1]
Objective [Heading]rr_ObjectiveHeadingINVESTMENT OBJECTIVE
Objective, Primary [Text Block]rr_ObjectivePrimaryTextBlockINTECH U.S. Core Fund seeks long-term growth of capital.
FEES AND EXPENSES OF THE FUNDjif277751_FundFeesAndExpensesAbstract 
Expense [Heading]rr_ExpenseHeadingFEES AND EXPENSES OF THE FUND
Expense Narrative [Text Block]rr_ExpenseNarrativeTextBlockThis table describes the fees and expenses that you may pay if you buy and hold Shares of the Fund.
SHAREHOLDER FEESrr_ShareholderFeesAbstract 
Shareholder Fees Caption [Text]rr_ShareholderFeesCaptionSHAREHOLDER FEES (fees paid directly from your investment)
ANNUAL FUND OPERATING EXPENSESrr_OperatingExpensesAbstract 
Operating Expenses Caption [Text]rr_OperatingExpensesCaptionANNUAL 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 Terminationrr_FeeWaiverOrReimbursementOverAssetsDateOfTerminationNovember 1, 2012
EXAMPLE:rr_ExpenseExampleAbstract 
Expense Example [Heading]rr_ExpenseExampleHeadingEXAMPLE:
Expense Example Narrative [Text Block]rr_ExpenseExampleNarrativeTextBlockThe 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 [Heading]rr_ExpenseExampleByYearHeadingThe 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:
Portfolio Turnover:jif277751_PortfolioTurnoverAltAbstract 
Portfolio Turnover [Heading]rr_PortfolioTurnoverHeadingPortfolio Turnover:
Portfolio Turnover [Text Block]rr_PortfolioTurnoverTextBlockThe 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 period, the Fund’s portfolio turnover rate was 93% of the average value of its portfolio.
Portfolio Turnover, Raterr_PortfolioTurnoverRate93.00%
Principal Investment Strategiesjif277751_PrincipalInvestmentStrategiesAbstract 
Strategy [Heading]rr_StrategyHeadingPRINCIPAL 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 the Fund 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.

[1]
Principal Investment Risksjif277751_PrincipalInvestmentRisksAbstract 
Risk [Heading]rr_RiskHeadingPRINCIPAL 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. On a routine basis, INTECH considers 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_RiskLoseMoneyThe biggest risk is that the Fund’s returns will vary, and you could lose money.
Risk Not Insured Depository Institution [Text]rr_RiskNotInsuredDepositoryInstitutionAn 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 INFORMATIONjif277751_FundPastPerformanceAbstract 
Bar Chart and Performance Table [Heading]rr_BarChartAndPerformanceTableHeadingPERFORMANCE 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_PerformanceAdditionalMarketIndexThe 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 Past Does Not Indicate Future [Text]rr_PerformancePastDoesNotIndicateFutureThe Fund’s past performance (before and after taxes) does not necessarily indicate how it will perform in the future.
Performance Table Closing [Text Block]rr_PerformanceTableClosingTextBlockUpdated performance information is available at janus.com/allfunds or by calling 1-800-525-3713.
Performance Availability Website Address [Text]rr_PerformanceAvailabilityWebSiteAddressjanus.com/allfunds
Performance Availability Phone [Text]rr_PerformanceAvailabilityPhone1-800-525-3713
Annual Total Returnsrr_BarChartTableAbstract 
Bar Chart [Heading]rr_BarChartHeadingAnnual Total Returns for Class D Shares (calendar year-end)
Bar Chart Closing [Text Block]rr_BarChartClosingTextBlockBest Quarter:  Second Quarter 2009  14.79%          Worst Quarter:  Fourth Quarter 2008  -21.49%
Year to Date Return, Labelrr_YearToDateReturnLabelThe Fund’s year-to-date return as of the calendar quarter ended September 30, 2011 was -6.32%.
Bar Chart, Year to Date Return, Daterr_BarChartYearToDateReturnDateSep. 30, 2011
Bar Chart, Year to Date Returnrr_BarChartYearToDateReturn(6.32%)
Average Annual Total Returnsrr_AverageAnnualReturnAbstract 
Captionrr_AverageAnnualReturnCaptionAverage Annual Total Returns (periods ended 12/31/10)
Performance Table Narrativerr_PerformanceTableNarrativeTextBlockAfter-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 Uses Highest Federal Raterr_PerformanceTableUsesHighestFederalRateAfter-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 Deferredrr_PerformanceTableNotRelevantToTaxDeferredActual 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.
INTECH U.S. Core Fund | Class D Shares | Class D
 
SHAREHOLDER FEESrr_ShareholderFeesAbstract 
Shareholder Fees Column [Text]rr_ShareholderFeesColumnNameClass D
Redemption fee on Shares held for 90 days or less (as a percentage of amount redeemed)rr_RedemptionFeeOverRedemption2.00%
ANNUAL FUND OPERATING EXPENSESrr_OperatingExpensesAbstract 
Operating Expenses Column [Text]rr_OperatingExpensesColumnNameClass D
Management Feesrr_ManagementFeesOverAssets0.52%
Other Expensesrr_OtherExpensesOverAssets0.31%
Total Annual Fund Operating Expensesrr_ExpensesOverAssets0.83%[24]
EXAMPLE:rr_ExpenseExampleAbstract 
Expense Example, By Year, Column [Text]rr_ExpenseExampleByYearColumnNameClass D Shares
1 Yearrr_ExpenseExampleYear0185
3 Yearsrr_ExpenseExampleYear03265
5 Yearsrr_ExpenseExampleYear05460
10 Yearsrr_ExpenseExampleYear101,025
Annual Total Returnsrr_BarChartTableAbstract 
2004rr_AnnualReturn200417.68%
2005rr_AnnualReturn200511.06%
2006rr_AnnualReturn200611.37%
2007rr_AnnualReturn20076.40%
2008rr_AnnualReturn2008(36.57%)
2009rr_AnnualReturn200922.91%
2010rr_AnnualReturn201016.38%
Highest Quarterly Return, Labelrr_HighestQuarterlyReturnLabelBest Quarter:
Highest Quarterly Return, Daterr_BarChartHighestQuarterlyReturnDateJun. 30, 2009
Highest Quarterly Returnrr_BarChartHighestQuarterlyReturn14.79%
Lowest Quarterly Return, Labelrr_LowestQuarterlyReturnLabelWorst Quarter:
Lowest Quarterly Return, Daterr_BarChartLowestQuarterlyReturnDateDec. 31, 2008
Lowest Quarterly Returnrr_BarChartLowestQuarterlyReturn(21.49%)
INTECH U.S. Core Fund | Class D Shares | Return Before Taxes | Class D
 
Average Annual Total Returnsrr_AverageAnnualReturnAbstract 
Columnrr_AverageAnnualReturnColumnNameClass D Shares
Labelrr_AverageAnnualReturnLabelReturn Before Taxes
1 Yearrr_AverageAnnualReturnYear0116.38%
5 Yearsrr_AverageAnnualReturnYear051.46%
Since Inceptionrr_AverageAnnualReturnSinceInception8.17%
Inception Daterr_AverageAnnualReturnInceptionDateFeb. 28, 2003
INTECH U.S. Core Fund | Class D Shares | Return After Taxes on Distributions | Class D
 
Average Annual Total Returnsrr_AverageAnnualReturnAbstract 
Columnrr_AverageAnnualReturnColumnNameClass D Shares
Labelrr_AverageAnnualReturnLabelReturn After Taxes on Distributions
1 Yearrr_AverageAnnualReturnYear0116.19%
5 Yearsrr_AverageAnnualReturnYear050.83%
Since Inceptionrr_AverageAnnualReturnSinceInception7.36%
Inception Daterr_AverageAnnualReturnInceptionDateFeb. 28, 2003
INTECH U.S. Core Fund | Class D Shares | Return After Taxes on Distributions and Sale of Fund Shares | Class D
 
Average Annual Total Returnsrr_AverageAnnualReturnAbstract 
Columnrr_AverageAnnualReturnColumnNameClass D Shares
Labelrr_AverageAnnualReturnLabelReturn After Taxes on Distributions and Sale of Fund Shares[5]
1 Yearrr_AverageAnnualReturnYear0110.89%
5 Yearsrr_AverageAnnualReturnYear051.24%
Since Inceptionrr_AverageAnnualReturnSinceInception7.04%
Inception Daterr_AverageAnnualReturnInceptionDateFeb. 28, 2003
INTECH U.S. Core Fund | Class D Shares | S&P 500® Index
 
Average Annual Total Returnsrr_AverageAnnualReturnAbstract 
Labelrr_AverageAnnualReturnLabelS&P 500® Index
Index No Deduction for Fees, Expenses, Taxes [Text]rr_IndexNoDeductionForFeesExpensesTaxes(reflects no deduction for expenses, fees, or taxes)
1 Yearrr_AverageAnnualReturnYear0115.06%
5 Yearsrr_AverageAnnualReturnYear052.29%
Since Inceptionrr_AverageAnnualReturnSinceInception7.38%
Inception Daterr_AverageAnnualReturnInceptionDateFeb. 28, 2003
INTECH U.S. Growth Fund | Class A, C, S, I, T Shares
 
Risk/Return:rr_RiskReturnAbstract 
Risk/Return [Heading]rr_RiskReturnHeadingFUND SUMMARY INTECH U.S. Growth Fund[1]
Objective [Heading]rr_ObjectiveHeadingINVESTMENT OBJECTIVE
Objective, Primary [Text Block]rr_ObjectivePrimaryTextBlockINTECH U.S. Growth Fund seeks long-term growth of capital.
FEES AND EXPENSES OF THE FUNDjif277751_FundFeesAndExpensesAbstract 
Expense [Heading]rr_ExpenseHeadingFEES AND EXPENSES OF THE FUND
Expense Narrative [Text Block]rr_ExpenseNarrativeTextBlockThis 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.
Expense Breakpoint Discountsjif277751_ExpenseBreakpointDiscountsAbstract 
Expense Breakpoint Discounts [Text]rr_ExpenseBreakpointDiscountsFor 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 41 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_ExpenseBreakpointMinimumInvestmentRequiredAmount50,000
SHAREHOLDER FEESrr_ShareholderFeesAbstract 
Shareholder Fees Caption [Text]rr_ShareholderFeesCaptionSHAREHOLDER FEES (fees paid directly from your investment)
ANNUAL FUND OPERATING EXPENSESrr_OperatingExpensesAbstract 
Operating Expenses Caption [Text]rr_OperatingExpensesCaptionANNUAL 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 Terminationrr_FeeWaiverOrReimbursementOverAssetsDateOfTerminationNovember 1, 2012
EXAMPLE:rr_ExpenseExampleAbstract 
Expense Example [Heading]rr_ExpenseExampleHeadingEXAMPLE:
Expense Example Narrative [Text Block]rr_ExpenseExampleNarrativeTextBlockThe 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 [Heading]rr_ExpenseExampleByYearHeadingThe 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 by, Year, Caption [Text]rr_ExpenseExampleByYearCaptionIf Shares are redeemed:
Expense Example, No Redemption:rr_ExpenseExampleNoRedemptionAbstract 
Expense Example, No Redemption, By Year, Caption [Text]rr_ExpenseExampleNoRedemptionByYearCaptionIf Shares are not redeemed:
Portfolio Turnover:jif277751_PortfolioTurnoverAltAbstract 
Portfolio Turnover [Heading]rr_PortfolioTurnoverHeadingPortfolio Turnover:
Portfolio Turnover [Text Block]rr_PortfolioTurnoverTextBlockThe 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 period, the Fund’s portfolio turnover rate was 96% of the average value of its portfolio.
Portfolio Turnover, Raterr_PortfolioTurnoverRate96.00%
Principal Investment Strategiesjif277751_PrincipalInvestmentStrategiesAbstract 
Strategy [Heading]rr_StrategyHeadingPRINCIPAL 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 the Fund 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.

[1]
Principal Investment Risksjif277751_PrincipalInvestmentRisksAbstract 
Risk [Heading]rr_RiskHeadingPRINCIPAL 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 return. 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. On a routine basis, INTECH considers 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_RiskLoseMoneyThe biggest risk is that the Fund’s returns will vary, and you could lose money.
Risk Not Insured Depository Institution [Text]rr_RiskNotInsuredDepositoryInstitutionAn 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 INFORMATIONjif277751_FundPastPerformanceAbstract 
Bar Chart and Performance Table [Heading]rr_BarChartAndPerformanceTableHeadingPERFORMANCE 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, without the effect of any 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, without the effect of any 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, without the effect of any 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.

Bar Chart Does Not Reflect Sales Loads [Text]rr_BarChartDoesNotReflectSalesLoadsThe 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.
Performance Additional Market Index [Text]rr_PerformanceAdditionalMarketIndexThe 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 Past Does Not Indicate Future [Text]rr_PerformancePastDoesNotIndicateFutureThe Fund’s past performance (before and after taxes) does not necessarily indicate how it will perform in the future.
Performance Table Closing [Text Block]rr_PerformanceTableClosingTextBlockUpdated performance information is available at janus.com/advisor/mutual-funds or by calling 1-877-335-2687.
Performance Availability Website Address [Text]rr_PerformanceAvailabilityWebSiteAddressjanus.com/advisor/mutual-funds
Performance Availability Phone [Text]rr_PerformanceAvailabilityPhone1-877-335-2687
Annual Total Returnsrr_BarChartTableAbstract 
Bar Chart [Heading]rr_BarChartHeadingAnnual Total Returns for Class S Shares (calendar year-end)
Bar Chart Closing [Text Block]rr_BarChartClosingTextBlockBest Quarter: Second Quarter 2009 15.04%           Worst Quarter: Fourth Quarter 2008 -25.11%
Year to Date Return, Labelrr_YearToDateReturnLabelThe Fund’s year-to-date return as of the calendar quarter ended September 30, 2011 was -6.98%.
Bar Chart, Year to Date Return, Daterr_BarChartYearToDateReturnDateSep. 30, 2011
Bar Chart, Year to Date Returnrr_BarChartYearToDateReturn(6.98%)
Average Annual Total Returnsrr_AverageAnnualReturnAbstract 
Captionrr_AverageAnnualReturnCaptionAverage Annual Total Returns (periods ended 12/31/10)
Performance Table Narrativerr_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 Uses Highest Federal Raterr_PerformanceTableUsesHighestFederalRateAfter-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 Deferredrr_PerformanceTableNotRelevantToTaxDeferredActual 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_PerformanceTableOneClassOfAfterTaxShownAfter-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.
INTECH U.S. Growth Fund | Class A, C, S, I, T Shares | Class A
 
SHAREHOLDER FEESrr_ShareholderFeesAbstract 
Shareholder Fees Column [Text]rr_ShareholderFeesColumnNameClass A
Maximum Sales Charge (load) Imposed on Purchases (as a percentage of offering price)rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice5.75%
Maximum Deferred Sales Charge (load) (as a percentage of the lower of original purchase price or redemption proceeds)rr_MaximumDeferredSalesChargeOverOther none
Redemption fee on Shares held for 90 days or less (as a percentage of amount redeemed)rr_RedemptionFeeOverRedemption none
ANNUAL FUND OPERATING EXPENSESrr_OperatingExpensesAbstract 
Operating Expenses Column [Text]rr_OperatingExpensesColumnNameClass A
Management Feesrr_ManagementFeesOverAssets0.50%
Distribution/Service (12b-1) Feesrr_DistributionAndService12b1FeesOverAssets0.25%
Other Expensesrr_OtherExpensesOverAssets0.12%
Total Annual Fund Operating Expensesrr_ExpensesOverAssets0.87%[25]
EXAMPLE:rr_ExpenseExampleAbstract 
Expense Example, By Year, Column [Text]rr_ExpenseExampleByYearColumnNameClass A Shares
1 Yearrr_ExpenseExampleYear01659
3 Yearsrr_ExpenseExampleYear03837
5 Yearsrr_ExpenseExampleYear051,029
10 Yearsrr_ExpenseExampleYear101,586
Expense Example, No Redemption:rr_ExpenseExampleNoRedemptionAbstract 
Expense Example, No Redemption, By Year, Column [Text]rr_ExpenseExampleNoRedemptionByYearColumnNameClass A Shares
1 Yearrr_ExpenseExampleNoRedemptionYear01659
3 Yearsrr_ExpenseExampleNoRedemptionYear03837
5 Yearsrr_ExpenseExampleNoRedemptionYear051,029
10 Yearsrr_ExpenseExampleNoRedemptionYear101,586
INTECH U.S. Growth Fund | Class A, C, S, I, T Shares | Class C
 
SHAREHOLDER FEESrr_ShareholderFeesAbstract 
Shareholder Fees Column [Text]rr_ShareholderFeesColumnNameClass 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_MaximumDeferredSalesChargeOverOther1.00%
Redemption fee on Shares held for 90 days or less (as a percentage of amount redeemed)rr_RedemptionFeeOverRedemption none
ANNUAL FUND OPERATING EXPENSESrr_OperatingExpensesAbstract 
Operating Expenses Column [Text]rr_OperatingExpensesColumnNameClass C
Management Feesrr_ManagementFeesOverAssets0.50%
Distribution/Service (12b-1) Feesrr_DistributionAndService12b1FeesOverAssets1.00%
Other Expensesrr_OtherExpensesOverAssets0.22%
Total Annual Fund Operating Expensesrr_ExpensesOverAssets1.72%[25]
EXAMPLE:rr_ExpenseExampleAbstract 
Expense Example, By Year, Column [Text]rr_ExpenseExampleByYearColumnNameClass C Shares
1 Yearrr_ExpenseExampleYear01275
3 Yearsrr_ExpenseExampleYear03542
5 Yearsrr_ExpenseExampleYear05933
10 Yearsrr_ExpenseExampleYear102,030
Expense Example, No Redemption:rr_ExpenseExampleNoRedemptionAbstract 
Expense Example, No Redemption, By Year, Column [Text]rr_ExpenseExampleNoRedemptionByYearColumnNameClass C Shares
1 Yearrr_ExpenseExampleNoRedemptionYear01175
3 Yearsrr_ExpenseExampleNoRedemptionYear03542
5 Yearsrr_ExpenseExampleNoRedemptionYear05933
10 Yearsrr_ExpenseExampleNoRedemptionYear102,030
INTECH U.S. Growth Fund | Class A, C, S, I, T Shares | Class I
 
SHAREHOLDER FEESrr_ShareholderFeesAbstract 
Shareholder Fees Column [Text]rr_ShareholderFeesColumnNameClass 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
Redemption fee on Shares held for 90 days or less (as a percentage of amount redeemed)rr_RedemptionFeeOverRedemption2.00%
ANNUAL FUND OPERATING EXPENSESrr_OperatingExpensesAbstract 
Operating Expenses Column [Text]rr_OperatingExpensesColumnNameClass I
Management Feesrr_ManagementFeesOverAssets0.50%
Distribution/Service (12b-1) Feesrr_DistributionAndService12b1FeesOverAssets none
Other Expensesrr_OtherExpensesOverAssets0.14%
Total Annual Fund Operating Expensesrr_ExpensesOverAssets0.64%[25]
EXAMPLE:rr_ExpenseExampleAbstract 
Expense Example, By Year, Column [Text]rr_ExpenseExampleByYearColumnNameClass I Shares
1 Yearrr_ExpenseExampleYear0165
3 Yearsrr_ExpenseExampleYear03205
5 Yearsrr_ExpenseExampleYear05357
10 Yearsrr_ExpenseExampleYear10798
Expense Example, No Redemption:rr_ExpenseExampleNoRedemptionAbstract 
Expense Example, No Redemption, By Year, Column [Text]rr_ExpenseExampleNoRedemptionByYearColumnNameClass I Shares
1 Yearrr_ExpenseExampleNoRedemptionYear0165
3 Yearsrr_ExpenseExampleNoRedemptionYear03205
5 Yearsrr_ExpenseExampleNoRedemptionYear05357
10 Yearsrr_ExpenseExampleNoRedemptionYear10798
INTECH U.S. Growth Fund | Class A, C, S, I, T Shares | Class S
 
SHAREHOLDER FEESrr_ShareholderFeesAbstract 
Shareholder Fees Column [Text]rr_ShareholderFeesColumnNameClass 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
Redemption fee on Shares held for 90 days or less (as a percentage of amount redeemed)rr_RedemptionFeeOverRedemption2.00%
ANNUAL FUND OPERATING EXPENSESrr_OperatingExpensesAbstract 
Operating Expenses Column [Text]rr_OperatingExpensesColumnNameClass S
Management Feesrr_ManagementFeesOverAssets0.50%
Distribution/Service (12b-1) Feesrr_DistributionAndService12b1FeesOverAssets0.25%
Other Expensesrr_OtherExpensesOverAssets0.33%
Total Annual Fund Operating Expensesrr_ExpensesOverAssets1.08%[25]
EXAMPLE:rr_ExpenseExampleAbstract 
Expense Example, By Year, Column [Text]rr_ExpenseExampleByYearColumnNameClass S Shares
1 Yearrr_ExpenseExampleYear01110
3 Yearsrr_ExpenseExampleYear03343
5 Yearsrr_ExpenseExampleYear05595
10 Yearsrr_ExpenseExampleYear101,317
Expense Example, No Redemption:rr_ExpenseExampleNoRedemptionAbstract 
Expense Example, No Redemption, By Year, Column [Text]rr_ExpenseExampleNoRedemptionByYearColumnNameClass S Shares
1 Yearrr_ExpenseExampleNoRedemptionYear01110
3 Yearsrr_ExpenseExampleNoRedemptionYear03343
5 Yearsrr_ExpenseExampleNoRedemptionYear05595
10 Yearsrr_ExpenseExampleNoRedemptionYear101,317
Annual Total Returnsrr_BarChartTableAbstract 
2004rr_AnnualReturn200412.34%
2005rr_AnnualReturn20056.90%
2006rr_AnnualReturn20066.90%
2007rr_AnnualReturn200710.30%
2008rr_AnnualReturn2008(42.71%)
2009rr_AnnualReturn200932.84%
2010rr_AnnualReturn201017.50%
Highest Quarterly Return, Labelrr_HighestQuarterlyReturnLabelBest Quarter:
Highest Quarterly Return, Daterr_BarChartHighestQuarterlyReturnDateJun. 30, 2009
Highest Quarterly Returnrr_BarChartHighestQuarterlyReturn15.04%
Lowest Quarterly Return, Labelrr_LowestQuarterlyReturnLabelWorst Quarter:
Lowest Quarterly Return, Daterr_BarChartLowestQuarterlyReturnDateDec. 30, 2008
Lowest Quarterly Returnrr_BarChartLowestQuarterlyReturn(25.11%)
INTECH U.S. Growth Fund | Class A, C, S, I, T Shares | Class T
 
SHAREHOLDER FEESrr_ShareholderFeesAbstract 
Shareholder Fees Column [Text]rr_ShareholderFeesColumnNameClass 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
Redemption fee on Shares held for 90 days or less (as a percentage of amount redeemed)rr_RedemptionFeeOverRedemption2.00%
ANNUAL FUND OPERATING EXPENSESrr_OperatingExpensesAbstract 
Operating Expenses Column [Text]rr_OperatingExpensesColumnNameClass T
Management Feesrr_ManagementFeesOverAssets0.50%
Distribution/Service (12b-1) Feesrr_DistributionAndService12b1FeesOverAssets none
Other Expensesrr_OtherExpensesOverAssets0.29%
Total Annual Fund Operating Expensesrr_ExpensesOverAssets0.79%[25]
EXAMPLE:rr_ExpenseExampleAbstract 
Expense Example, By Year, Column [Text]rr_ExpenseExampleByYearColumnNameClass T Shares
1 Yearrr_ExpenseExampleYear0181
3 Yearsrr_ExpenseExampleYear03252
5 Yearsrr_ExpenseExampleYear05439
10 Yearsrr_ExpenseExampleYear10978
Expense Example, No Redemption:rr_ExpenseExampleNoRedemptionAbstract 
Expense Example, No Redemption, By Year, Column [Text]rr_ExpenseExampleNoRedemptionByYearColumnNameClass T Shares
1 Yearrr_ExpenseExampleNoRedemptionYear0181
3 Yearsrr_ExpenseExampleNoRedemptionYear03252
5 Yearsrr_ExpenseExampleNoRedemptionYear05439
10 Yearsrr_ExpenseExampleNoRedemptionYear10978
INTECH U.S. Growth Fund | Class A, C, S, I, T Shares | Return Before Taxes | Class A
 
Average Annual Total Returnsrr_AverageAnnualReturnAbstract 
Columnrr_AverageAnnualReturnColumnNameClass A Shares
Labelrr_AverageAnnualReturnLabelReturn Before Taxes[3]
1 Yearrr_AverageAnnualReturnYear0110.82%
5 Yearsrr_AverageAnnualReturnYear050.08%
Since Inceptionrr_AverageAnnualReturnSinceInception5.32%
Inception Daterr_AverageAnnualReturnInceptionDateJan. 02, 2003
INTECH U.S. Growth Fund | Class A, C, S, I, T Shares | Return Before Taxes | Class C
 
Average Annual Total Returnsrr_AverageAnnualReturnAbstract 
Columnrr_AverageAnnualReturnColumnNameClass C Shares
Labelrr_AverageAnnualReturnLabelReturn Before Taxes[4]
1 Yearrr_AverageAnnualReturnYear0115.19%
5 Yearsrr_AverageAnnualReturnYear050.42%
Since Inceptionrr_AverageAnnualReturnSinceInception5.29%
Inception Daterr_AverageAnnualReturnInceptionDateJan. 02, 2003
INTECH U.S. Growth Fund | Class A, C, S, I, T Shares | Return Before Taxes | Class I
 
Average Annual Total Returnsrr_AverageAnnualReturnAbstract 
Columnrr_AverageAnnualReturnColumnNameClass I Shares
Labelrr_AverageAnnualReturnLabelReturn Before Taxes
1 Yearrr_AverageAnnualReturnYear0117.95%
5 Yearsrr_AverageAnnualReturnYear051.54%
Since Inceptionrr_AverageAnnualReturnSinceInception5.91%
Inception Daterr_AverageAnnualReturnInceptionDateJan. 02, 2003
INTECH U.S. Growth Fund | Class A, C, S, I, T Shares | Return Before Taxes | Class S
 
Average Annual Total Returnsrr_AverageAnnualReturnAbstract 
Columnrr_AverageAnnualReturnColumnNameClass S Shares
Labelrr_AverageAnnualReturnLabelReturn Before Taxes
1 Yearrr_AverageAnnualReturnYear0117.50%
5 Yearsrr_AverageAnnualReturnYear051.06%
Since Inceptionrr_AverageAnnualReturnSinceInception5.91%
Inception Daterr_AverageAnnualReturnInceptionDateJan. 02, 2003
INTECH U.S. Growth Fund | Class A, C, S, I, T Shares | Return Before Taxes | Class T
 
Average Annual Total Returnsrr_AverageAnnualReturnAbstract 
Columnrr_AverageAnnualReturnColumnNameClass T Shares
Labelrr_AverageAnnualReturnLabelReturn Before Taxes
1 Yearrr_AverageAnnualReturnYear0117.77%
5 Yearsrr_AverageAnnualReturnYear051.06%
Since Inceptionrr_AverageAnnualReturnSinceInception5.91%
Inception Daterr_AverageAnnualReturnInceptionDateJan. 02, 2003
INTECH U.S. Growth Fund | Class A, C, S, I, T Shares | Return After Taxes on Distributions | Class S
 
Average Annual Total Returnsrr_AverageAnnualReturnAbstract 
Columnrr_AverageAnnualReturnColumnNameClass S Shares
Labelrr_AverageAnnualReturnLabelReturn After Taxes on Distributions
1 Yearrr_AverageAnnualReturnYear0117.37%
5 Yearsrr_AverageAnnualReturnYear050.85%
Since Inceptionrr_AverageAnnualReturnSinceInception5.33%
Inception Daterr_AverageAnnualReturnInceptionDateJan. 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
 
Average Annual Total Returnsrr_AverageAnnualReturnAbstract 
Columnrr_AverageAnnualReturnColumnNameClass S Shares
Labelrr_AverageAnnualReturnLabelReturn After Taxes on Distributions and Sale of Fund Shares[5]
1 Yearrr_AverageAnnualReturnYear0111.55%
5 Yearsrr_AverageAnnualReturnYear050.89%
Since Inceptionrr_AverageAnnualReturnSinceInception4.95%
Inception Daterr_AverageAnnualReturnInceptionDateJan. 02, 2003
INTECH U.S. Growth Fund | Class A, C, S, I, T Shares | Russell 1000® Growth Index
 
Average Annual Total Returnsrr_AverageAnnualReturnAbstract 
Labelrr_AverageAnnualReturnLabelRussell 1000® Growth Index
Index No Deduction for Fees, Expenses, Taxes [Text]rr_IndexNoDeductionForFeesExpensesTaxes(reflects no deduction for expenses, fees, or taxes)
1 Yearrr_AverageAnnualReturnYear0116.71%
5 Yearsrr_AverageAnnualReturnYear053.75%
Since Inceptionrr_AverageAnnualReturnSinceInception6.77%
Inception Daterr_AverageAnnualReturnInceptionDateJan. 02, 2003
INTECH U.S. Value Fund | Class A, C, S, I, T Shares
 
Risk/Return:rr_RiskReturnAbstract 
Risk/Return [Heading]rr_RiskReturnHeadingFUND SUMMARY INTECH U.S. Value Fund[1]
Objective [Heading]rr_ObjectiveHeadingINVESTMENT OBJECTIVE
Objective, Primary [Text Block]rr_ObjectivePrimaryTextBlockINTECH U.S. Value Fund seeks long-term growth of capital.
FEES AND EXPENSES OF THE FUNDjif277751_FundFeesAndExpensesAbstract 
Expense [Heading]rr_ExpenseHeadingFEES AND EXPENSES OF THE FUND
Expense Narrative [Text Block]rr_ExpenseNarrativeTextBlockThis 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.
Expense Breakpoint Discountsjif277751_ExpenseBreakpointDiscountsAbstract 
Expense Breakpoint Discounts [Text]rr_ExpenseBreakpointDiscountsFor 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 41 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_ExpenseBreakpointMinimumInvestmentRequiredAmount50,000
SHAREHOLDER FEESrr_ShareholderFeesAbstract 
Shareholder Fees Caption [Text]rr_ShareholderFeesCaptionSHAREHOLDER FEES (fees paid directly from your investment)
ANNUAL FUND OPERATING EXPENSESrr_OperatingExpensesAbstract 
Operating Expenses Caption [Text]rr_OperatingExpensesCaptionANNUAL 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 Terminationrr_FeeWaiverOrReimbursementOverAssetsDateOfTerminationNovember 1, 2012
EXAMPLE:rr_ExpenseExampleAbstract 
Expense Example [Heading]rr_ExpenseExampleHeadingEXAMPLE:
Expense Example Narrative [Text Block]rr_ExpenseExampleNarrativeTextBlockThe 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 [Heading]rr_ExpenseExampleByYearHeadingThe 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 by, Year, Caption [Text]rr_ExpenseExampleByYearCaptionIf Shares are redeemed:
Expense Example, No Redemption:rr_ExpenseExampleNoRedemptionAbstract 
Expense Example, No Redemption, By Year, Caption [Text]rr_ExpenseExampleNoRedemptionByYearCaptionIf Shares are not redeemed:
Portfolio Turnover:jif277751_PortfolioTurnoverAltAbstract 
Portfolio Turnover [Heading]rr_PortfolioTurnoverHeadingPortfolio Turnover:
Portfolio Turnover [Text Block]rr_PortfolioTurnoverTextBlockThe 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 period, the Fund’s portfolio turnover rate was 108% of the average value of its portfolio.
Portfolio Turnover, Raterr_PortfolioTurnoverRate108.00%
Principal Investment Strategiesjif277751_PrincipalInvestmentStrategiesAbstract 
Strategy [Heading]rr_StrategyHeadingPRINCIPAL 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 the Fund 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.

[1]
Principal Investment Risksjif277751_PrincipalInvestmentRisksAbstract 
Risk [Heading]rr_RiskHeadingPRINCIPAL 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.

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. On a routine basis, INTECH considers 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_RiskLoseMoneyThe biggest risk is that the Fund’s returns will vary, and you could lose money.
Risk Not Insured Depository Institution [Text]rr_RiskNotInsuredDepositoryInstitutionAn 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 INFORMATIONjif277751_FundPastPerformanceAbstract 
Bar Chart and Performance Table [Heading]rr_BarChartAndPerformanceTableHeadingPERFORMANCE 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.

Bar Chart Does Not Reflect Sales Loads [Text]rr_BarChartDoesNotReflectSalesLoadsThe 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.
Performance Additional Market Index [Text]rr_PerformanceAdditionalMarketIndexThe 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 Past Does Not Indicate Future [Text]rr_PerformancePastDoesNotIndicateFutureThe Fund’s past performance (before and after taxes) does not necessarily indicate how it will perform in the future.
Performance Table Closing [Text Block]rr_PerformanceTableClosingTextBlockUpdated performance information is available at janus.com/advisor/mutual-funds or by calling 1-877-335-2687.
Performance Availability Website Address [Text]rr_PerformanceAvailabilityWebSiteAddressjanus.com/advisor/mutual-funds
Performance Availability Phone [Text]rr_PerformanceAvailabilityPhone1-877-335-2687
Annual Total Returnsrr_BarChartTableAbstract 
Bar Chart [Heading]rr_BarChartHeadingAnnual Total Returns for Class I Shares (calendar year-end)
Bar Chart Closing [Text Block]rr_BarChartClosingTextBlockBest Quarter:  Third Quarter 2009  17.79%          Worst Quarter:  Fourth Quarter 2008  -21.39%
Year to Date Return, Labelrr_YearToDateReturnLabelThe Fund’s year-to-date return as of the calendar quarter ended September 30, 2011 was -9.95%.
Bar Chart, Year to Date Return, Daterr_BarChartYearToDateReturnDateSep. 30, 2011
Bar Chart, Year to Date Returnrr_BarChartYearToDateReturn(9.95%)
Average Annual Total Returnsrr_AverageAnnualReturnAbstract 
Captionrr_AverageAnnualReturnCaptionAverage Annual Total Returns (periods ended 12/31/10)
Performance Table Narrativerr_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 Uses Highest Federal Raterr_PerformanceTableUsesHighestFederalRateAfter-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 Deferredrr_PerformanceTableNotRelevantToTaxDeferredActual 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_PerformanceTableOneClassOfAfterTaxShownAfter-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.
INTECH U.S. Value Fund | Class A, C, S, I, T Shares | Class A
 
SHAREHOLDER FEESrr_ShareholderFeesAbstract 
Shareholder Fees Column [Text]rr_ShareholderFeesColumnNameClass A
Maximum Sales Charge (load) Imposed on Purchases (as a percentage of offering price)rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice5.75%
Maximum Deferred Sales Charge (load) (as a percentage of the lower of original purchase price or redemption proceeds)rr_MaximumDeferredSalesChargeOverOther none
Redemption fee on Shares held for 90 days or less (as a percentage of amount redeemed)rr_RedemptionFeeOverRedemption none
ANNUAL FUND OPERATING EXPENSESrr_OperatingExpensesAbstract 
Operating Expenses Column [Text]rr_OperatingExpensesColumnNameClass A
Management Feesrr_ManagementFeesOverAssets0.50%
Distribution/Service (12b-1) Feesrr_DistributionAndService12b1FeesOverAssets0.25%
Other Expensesrr_OtherExpensesOverAssets0.21%
Total Annual Fund Operating Expensesrr_ExpensesOverAssets0.96%[26]
EXAMPLE:rr_ExpenseExampleAbstract 
Expense Example, By Year, Column [Text]rr_ExpenseExampleByYearColumnNameClass A Shares
1 Yearrr_ExpenseExampleYear01667
3 Yearsrr_ExpenseExampleYear03863
5 Yearsrr_ExpenseExampleYear051,075
10 Yearsrr_ExpenseExampleYear101,685
Expense Example, No Redemption:rr_ExpenseExampleNoRedemptionAbstract 
Expense Example, No Redemption, By Year, Column [Text]rr_ExpenseExampleNoRedemptionByYearColumnNameClass A Shares
1 Yearrr_ExpenseExampleNoRedemptionYear01667
3 Yearsrr_ExpenseExampleNoRedemptionYear03863
5 Yearsrr_ExpenseExampleNoRedemptionYear051,075
10 Yearsrr_ExpenseExampleNoRedemptionYear101,685
INTECH U.S. Value Fund | Class A, C, S, I, T Shares | Class C
 
SHAREHOLDER FEESrr_ShareholderFeesAbstract 
Shareholder Fees Column [Text]rr_ShareholderFeesColumnNameClass 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_MaximumDeferredSalesChargeOverOther1.00%
Redemption fee on Shares held for 90 days or less (as a percentage of amount redeemed)rr_RedemptionFeeOverRedemption none
ANNUAL FUND OPERATING EXPENSESrr_OperatingExpensesAbstract 
Operating Expenses Column [Text]rr_OperatingExpensesColumnNameClass C
Management Feesrr_ManagementFeesOverAssets0.50%
Distribution/Service (12b-1) Feesrr_DistributionAndService12b1FeesOverAssets1.00%
Other Expensesrr_OtherExpensesOverAssets0.25%
Total Annual Fund Operating Expensesrr_ExpensesOverAssets1.75%[26]
EXAMPLE:rr_ExpenseExampleAbstract 
Expense Example, By Year, Column [Text]rr_ExpenseExampleByYearColumnNameClass C Shares
1 Yearrr_ExpenseExampleYear01278
3 Yearsrr_ExpenseExampleYear03551
5 Yearsrr_ExpenseExampleYear05949
10 Yearsrr_ExpenseExampleYear102,062
Expense Example, No Redemption:rr_ExpenseExampleNoRedemptionAbstract 
Expense Example, No Redemption, By Year, Column [Text]rr_ExpenseExampleNoRedemptionByYearColumnNameClass C Shares
1 Yearrr_ExpenseExampleNoRedemptionYear01178
3 Yearsrr_ExpenseExampleNoRedemptionYear03551
5 Yearsrr_ExpenseExampleNoRedemptionYear05949
10 Yearsrr_ExpenseExampleNoRedemptionYear102,062
INTECH U.S. Value Fund | Class A, C, S, I, T Shares | Class S
 
SHAREHOLDER FEESrr_ShareholderFeesAbstract 
Shareholder Fees Column [Text]rr_ShareholderFeesColumnNameClass 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
Redemption fee on Shares held for 90 days or less (as a percentage of amount redeemed)rr_RedemptionFeeOverRedemption2.00%
ANNUAL FUND OPERATING EXPENSESrr_OperatingExpensesAbstract 
Operating Expenses Column [Text]rr_OperatingExpensesColumnNameClass S
Management Feesrr_ManagementFeesOverAssets0.50%
Distribution/Service (12b-1) Feesrr_DistributionAndService12b1FeesOverAssets0.25%
Other Expensesrr_OtherExpensesOverAssets0.43%
Total Annual Fund Operating Expensesrr_ExpensesOverAssets1.18%[26]
EXAMPLE:rr_ExpenseExampleAbstract 
Expense Example, By Year, Column [Text]rr_ExpenseExampleByYearColumnNameClass S Shares
1 Yearrr_ExpenseExampleYear01120
3 Yearsrr_ExpenseExampleYear03375
5 Yearsrr_ExpenseExampleYear05649
10 Yearsrr_ExpenseExampleYear101,432
Expense Example, No Redemption:rr_ExpenseExampleNoRedemptionAbstract 
Expense Example, No Redemption, By Year, Column [Text]rr_ExpenseExampleNoRedemptionByYearColumnNameClass S Shares
1 Yearrr_ExpenseExampleNoRedemptionYear01120
3 Yearsrr_ExpenseExampleNoRedemptionYear03375
5 Yearsrr_ExpenseExampleNoRedemptionYear05649
10 Yearsrr_ExpenseExampleNoRedemptionYear101,432
INTECH U.S. Value Fund | Class A, C, S, I, T Shares | Class I
 
SHAREHOLDER FEESrr_ShareholderFeesAbstract 
Shareholder Fees Column [Text]rr_ShareholderFeesColumnNameClass 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
Redemption fee on Shares held for 90 days or less (as a percentage of amount redeemed)rr_RedemptionFeeOverRedemption2.00%
ANNUAL FUND OPERATING EXPENSESrr_OperatingExpensesAbstract 
Operating Expenses Column [Text]rr_OperatingExpensesColumnNameClass I
Management Feesrr_ManagementFeesOverAssets0.50%
Distribution/Service (12b-1) Feesrr_DistributionAndService12b1FeesOverAssets none
Other Expensesrr_OtherExpensesOverAssets0.19%
Total Annual Fund Operating Expensesrr_ExpensesOverAssets0.69%[26]
EXAMPLE:rr_ExpenseExampleAbstract 
Expense Example, By Year, Column [Text]rr_ExpenseExampleByYearColumnNameClass I Shares
1 Yearrr_ExpenseExampleYear0170
3 Yearsrr_ExpenseExampleYear03221
5 Yearsrr_ExpenseExampleYear05384
10 Yearsrr_ExpenseExampleYear10859
Expense Example, No Redemption:rr_ExpenseExampleNoRedemptionAbstract 
Expense Example, No Redemption, By Year, Column [Text]rr_ExpenseExampleNoRedemptionByYearColumnNameClass I Shares
1 Yearrr_ExpenseExampleNoRedemptionYear0170
3 Yearsrr_ExpenseExampleNoRedemptionYear03221
5 Yearsrr_ExpenseExampleNoRedemptionYear05384
10 Yearsrr_ExpenseExampleNoRedemptionYear10859
Annual Total Returnsrr_BarChartTableAbstract 
2006rr_AnnualReturn200617.72%
2007rr_AnnualReturn20071.47%
2008rr_AnnualReturn2008(34.79%)
2009rr_AnnualReturn200917.99%
2010rr_AnnualReturn201015.41%
Highest Quarterly Return, Labelrr_HighestQuarterlyReturnLabelBest Quarter:
Highest Quarterly Return, Daterr_BarChartHighestQuarterlyReturnDateSep. 30, 2009
Highest Quarterly Returnrr_BarChartHighestQuarterlyReturn17.79%
Lowest Quarterly Return, Labelrr_LowestQuarterlyReturnLabelWorst Quarter:
Lowest Quarterly Return, Daterr_BarChartLowestQuarterlyReturnDateDec. 31, 2008
Lowest Quarterly Returnrr_BarChartLowestQuarterlyReturn(21.39%)
INTECH U.S. Value Fund | Class A, C, S, I, T Shares | Class T
 
SHAREHOLDER FEESrr_ShareholderFeesAbstract 
Shareholder Fees Column [Text]rr_ShareholderFeesColumnNameClass 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
Redemption fee on Shares held for 90 days or less (as a percentage of amount redeemed)rr_RedemptionFeeOverRedemption2.00%
ANNUAL FUND OPERATING EXPENSESrr_OperatingExpensesAbstract 
Operating Expenses Column [Text]rr_OperatingExpensesColumnNameClass T
Management Feesrr_ManagementFeesOverAssets0.50%
Distribution/Service (12b-1) Feesrr_DistributionAndService12b1FeesOverAssets none
Other Expensesrr_OtherExpensesOverAssets0.46%
Total Annual Fund Operating Expensesrr_ExpensesOverAssets0.96%[26]
EXAMPLE:rr_ExpenseExampleAbstract 
Expense Example, By Year, Column [Text]rr_ExpenseExampleByYearColumnNameClass T Shares
1 Yearrr_ExpenseExampleYear0198
3 Yearsrr_ExpenseExampleYear03306
5 Yearsrr_ExpenseExampleYear05531
10 Yearsrr_ExpenseExampleYear101,178
Expense Example, No Redemption:rr_ExpenseExampleNoRedemptionAbstract 
Expense Example, No Redemption, By Year, Column [Text]rr_ExpenseExampleNoRedemptionByYearColumnNameClass T Shares
1 Yearrr_ExpenseExampleNoRedemptionYear0198
3 Yearsrr_ExpenseExampleNoRedemptionYear03306
5 Yearsrr_ExpenseExampleNoRedemptionYear05531
10 Yearsrr_ExpenseExampleNoRedemptionYear101,178
INTECH U.S. Value Fund | Class A, C, S, I, T Shares | Return Before Taxes | Class A
 
Average Annual Total Returnsrr_AverageAnnualReturnAbstract 
Columnrr_AverageAnnualReturnColumnNameClass A Shares
Labelrr_AverageAnnualReturnLabelReturn Before Taxes[3]
1 Yearrr_AverageAnnualReturnYear018.39%
5 Yearsrr_AverageAnnualReturnYear05(0.23%)
Since Inceptionrr_AverageAnnualReturnSinceInception(0.23%)
Inception Daterr_AverageAnnualReturnInceptionDateDec. 30, 2005
INTECH U.S. Value Fund | Class A, C, S, I, T Shares | Return Before Taxes | Class C
 
Average Annual Total Returnsrr_AverageAnnualReturnAbstract 
Columnrr_AverageAnnualReturnColumnNameClass C Shares
Labelrr_AverageAnnualReturnLabelReturn Before Taxes[4]
1 Yearrr_AverageAnnualReturnYear0113.10%
5 Yearsrr_AverageAnnualReturnYear050.21%
Since Inceptionrr_AverageAnnualReturnSinceInception0.21%
Inception Daterr_AverageAnnualReturnInceptionDateDec. 30, 2005
INTECH U.S. Value Fund | Class A, C, S, I, T Shares | Return Before Taxes | Class S
 
Average Annual Total Returnsrr_AverageAnnualReturnAbstract 
Columnrr_AverageAnnualReturnColumnNameClass S Shares
Labelrr_AverageAnnualReturnLabelReturn Before Taxes
1 Yearrr_AverageAnnualReturnYear0114.81%
5 Yearsrr_AverageAnnualReturnYear050.71%
Since Inceptionrr_AverageAnnualReturnSinceInception0.71%
Inception Daterr_AverageAnnualReturnInceptionDateDec. 30, 2005
INTECH U.S. Value Fund | Class A, C, S, I, T Shares | Return Before Taxes | Class I
 
Average Annual Total Returnsrr_AverageAnnualReturnAbstract 
Columnrr_AverageAnnualReturnColumnNameClass I Shares
Labelrr_AverageAnnualReturnLabelReturn Before Taxes
1 Yearrr_AverageAnnualReturnYear0115.41%
5 Yearsrr_AverageAnnualReturnYear051.19%
Since Inceptionrr_AverageAnnualReturnSinceInception1.19%
Inception Daterr_AverageAnnualReturnInceptionDateDec. 30, 2005
INTECH U.S. Value Fund | Class A, C, S, I, T Shares | Return Before Taxes | Class T
 
Average Annual Total Returnsrr_AverageAnnualReturnAbstract 
Columnrr_AverageAnnualReturnColumnNameClass T Shares
Labelrr_AverageAnnualReturnLabelReturn Before Taxes
1 Yearrr_AverageAnnualReturnYear0115.29%
5 Yearsrr_AverageAnnualReturnYear050.75%
Since Inceptionrr_AverageAnnualReturnSinceInception0.74%
Inception Daterr_AverageAnnualReturnInceptionDateDec. 30, 2005
INTECH U.S. Value Fund | Class A, C, S, I, T Shares | Return After Taxes on Distributions | Class I
 
Average Annual Total Returnsrr_AverageAnnualReturnAbstract 
Columnrr_AverageAnnualReturnColumnNameClass I Shares
Labelrr_AverageAnnualReturnLabelReturn After Taxes on Distributions
1 Yearrr_AverageAnnualReturnYear0115.18%
5 Yearsrr_AverageAnnualReturnYear050.75%
Since Inceptionrr_AverageAnnualReturnSinceInception0.75%
Inception Daterr_AverageAnnualReturnInceptionDateDec. 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
 
Average Annual Total Returnsrr_AverageAnnualReturnAbstract 
Columnrr_AverageAnnualReturnColumnNameClass I Shares
Labelrr_AverageAnnualReturnLabelReturn After Taxes on Distributions and Sale of Fund Shares[5]
1 Yearrr_AverageAnnualReturnYear0110.32%
5 Yearsrr_AverageAnnualReturnYear050.90%
Since Inceptionrr_AverageAnnualReturnSinceInception0.90%
Inception Daterr_AverageAnnualReturnInceptionDateDec. 30, 2005
INTECH U.S. Value Fund | Class A, C, S, I, T Shares | Russell 1000® Value Index
 
Average Annual Total Returnsrr_AverageAnnualReturnAbstract 
Labelrr_AverageAnnualReturnLabelRussell 1000® Value Index
Index No Deduction for Fees, Expenses, Taxes [Text]rr_IndexNoDeductionForFeesExpensesTaxes(reflects no deduction for expenses, fees, or taxes)
1 Yearrr_AverageAnnualReturnYear0115.51%
5 Yearsrr_AverageAnnualReturnYear051.28%
Since Inceptionrr_AverageAnnualReturnSinceInception1.28%
Inception Daterr_AverageAnnualReturnInceptionDateDec. 30, 2005
Janus Government Money Market Fund | Class D Shares
 
Risk/Return:rr_RiskReturnAbstract 
Risk/Return [Heading]rr_RiskReturnHeadingFUND SUMMARY Janus Government Money Market Fund
Objective [Heading]rr_ObjectiveHeadingINVESTMENT OBJECTIVES
Objective, Primary [Text Block]rr_ObjectivePrimaryTextBlockJanus Government Money Market Fund seeks capital preservation and liquidity
Objective, Secondary [Text Block]rr_ObjectiveSecondaryTextBlockwith current income as a secondary objective.
FEES AND EXPENSES OF THE FUNDjif277751_FundFeesAndExpensesAbstract 
Expense [Heading]rr_ExpenseHeadingFEES AND EXPENSES OF THE FUND
Expense Narrative [Text Block]rr_ExpenseNarrativeTextBlockThis table describes the fees and expenses that you may pay if you buy and hold Shares of the Fund.
ANNUAL FUND OPERATING EXPENSESrr_OperatingExpensesAbstract 
Operating Expenses Caption [Text]rr_OperatingExpensesCaptionANNUAL FUND OPERATING EXPENSES (expenses that you pay each year as a percentage of the value of your investment)
EXAMPLE:rr_ExpenseExampleAbstract 
Expense Example [Heading]rr_ExpenseExampleHeadingEXAMPLE:
Expense Example Narrative [Text Block]rr_ExpenseExampleNarrativeTextBlockThe 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 [Heading]rr_ExpenseExampleByYearHeadingThe 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:
Principal Investment Strategiesjif277751_PrincipalInvestmentStrategiesAbstract 
Strategy [Heading]rr_StrategyHeadingPRINCIPAL 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

Principal Investment Risksjif277751_PrincipalInvestmentRisksAbstract 
Risk [Heading]rr_RiskHeadingPRINCIPAL 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_RiskMoneyMarketFundMoney 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 INFORMATIONjif277751_FundPastPerformanceAbstract 
Bar Chart and Performance Table [Heading]rr_BarChartAndPerformanceTableHeadingPERFORMANCE 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 Past Does Not Indicate Future [Text]rr_PerformancePastDoesNotIndicateFutureThe Fund’s past performance does not necessarily indicate how it will perform in the future.
Performance Table Closing [Text Block]rr_PerformanceTableClosingTextBlockUpdated performance information is available at janus.com/allfunds or by calling 1-800-525-3713.
Performance Availability Website Address [Text]rr_PerformanceAvailabilityWebSiteAddressjanus.com/allfunds
Performance Availability Phone [Text]rr_PerformanceAvailabilityPhone1-800-525-3713
Annual Total Returnsrr_BarChartTableAbstract 
Bar Chart [Heading]rr_BarChartHeadingAnnual Total Returns for Class D Shares (calendar year-end)
Bar Chart Closing [Text Block]rr_BarChartClosingTextBlock

Best Quarter:  First Quarter 2001  1.31%          Worst Quarter: Fourth Quarter 2010 0.00%

Year to Date Return, Labelrr_YearToDateReturnLabelThe Fund’s year-to-date return as of the calendar quarter ended September 30, 2011 was 0.00%.
Bar Chart, Year to Date Return, Daterr_BarChartYearToDateReturnDateSep. 30, 2011
Bar Chart, Year to Date Returnrr_BarChartYearToDateReturn0.00%
Average Annual Total Returnsrr_AverageAnnualReturnAbstract 
Captionrr_AverageAnnualReturnCaptionAverage Annual Total Returns (periods ended 12/31/10)
Money Market Seven Day Yield, Caption [Text]rr_MoneyMarketSevenDayYieldCaptionThe 7-day yield on December 31, 2010 was 0.00% for Janus Government Money Market Fund.
Money Market Seven Day Yieldrr_MoneyMarketSevenDayYield0.00%
Janus Government Money Market Fund | Class D Shares | Class D
 
ANNUAL FUND OPERATING EXPENSESrr_OperatingExpensesAbstract 
Operating Expenses Column [Text]rr_OperatingExpensesColumnNameClass D
Management Feesrr_ManagementFeesOverAssets0.20%
Other Expensesrr_OtherExpensesOverAssets0.51%
Total Annual Fund Operating Expensesrr_ExpensesOverAssets0.71%
EXAMPLE:rr_ExpenseExampleAbstract 
Expense Example, By Year, Column [Text]rr_ExpenseExampleByYearColumnNameClass D Shares
1 Yearrr_ExpenseExampleYear0173
3 Yearsrr_ExpenseExampleYear03227
5 Yearsrr_ExpenseExampleYear05395
10 Yearsrr_ExpenseExampleYear10883
Annual Total Returnsrr_BarChartTableAbstract 
2001rr_AnnualReturn20013.73%
2002rr_AnnualReturn20021.33%
2003rr_AnnualReturn20030.65%
2004rr_AnnualReturn20040.85%
2005rr_AnnualReturn20052.70%
2006rr_AnnualReturn20064.52%
2007rr_AnnualReturn20074.66%
2008rr_AnnualReturn20081.83%
2009rr_AnnualReturn20090.01%
2010rr_AnnualReturn20100.02%
Highest Quarterly Return, Labelrr_HighestQuarterlyReturnLabelBest Quarter:
Highest Quarterly Return, Daterr_BarChartHighestQuarterlyReturnDateMar. 31, 2001
Highest Quarterly Returnrr_BarChartHighestQuarterlyReturn1.31%
Lowest Quarterly Return, Labelrr_LowestQuarterlyReturnLabelWorst Quarter:
Lowest Quarterly Return, Daterr_BarChartLowestQuarterlyReturnDateDec. 31, 2010
Lowest Quarterly Returnrr_BarChartLowestQuarterlyReturn0.00%
Janus Government Money Market Fund | Class D Shares | Return Before Taxes | Class D
 
Average Annual Total Returnsrr_AverageAnnualReturnAbstract 
Columnrr_AverageAnnualReturnColumnNameClass D Shares
Labelrr_AverageAnnualReturnLabelReturn Before Taxes
1 Yearrr_AverageAnnualReturnYear010.02%
5 Yearsrr_AverageAnnualReturnYear052.19%
10 Yearsrr_AverageAnnualReturnYear102.02%
Since Inceptionrr_AverageAnnualReturnSinceInception3.18%
Inception Daterr_AverageAnnualReturnInceptionDateFeb. 14, 1995
Janus Government Money Market Fund | Class T Shares
 
Risk/Return:rr_RiskReturnAbstract 
Risk/Return [Heading]rr_RiskReturnHeadingFUND SUMMARY Janus Government Money Market Fund
Objective [Heading]rr_ObjectiveHeadingINVESTMENT OBJECTIVES
Objective, Primary [Text Block]rr_ObjectivePrimaryTextBlockJanus Government Money Market Fund seeks capital preservation and liquidity
Objective, Secondary [Text Block]rr_ObjectiveSecondaryTextBlockwith current income as a secondary objective.
FEES AND EXPENSES OF THE FUNDjif277751_FundFeesAndExpensesAbstract 
Expense [Heading]rr_ExpenseHeadingFEES AND EXPENSES OF THE FUND
Expense Narrative [Text Block]rr_ExpenseNarrativeTextBlockThis table describes the fees and expenses that you may pay if you buy and hold Shares of the Fund.
ANNUAL FUND OPERATING EXPENSESrr_OperatingExpensesAbstract 
Operating Expenses Caption [Text]rr_OperatingExpensesCaptionANNUAL FUND OPERATING EXPENSES (expenses that you pay each year as a percentage of the value of your investment)
EXAMPLE:rr_ExpenseExampleAbstract 
Expense Example [Heading]rr_ExpenseExampleHeadingEXAMPLE:
Expense Example Narrative [Text Block]rr_ExpenseExampleNarrativeTextBlockThe 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 [Heading]rr_ExpenseExampleByYearHeadingThe 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:
Principal Investment Strategiesjif277751_PrincipalInvestmentStrategiesAbstract 
Strategy [Heading]rr_StrategyHeadingPRINCIPAL 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

Principal Investment Risksjif277751_PrincipalInvestmentRisksAbstract 
Risk [Heading]rr_RiskHeadingPRINCIPAL 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_RiskMoneyMarketFundMoney 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 INFORMATIONjif277751_FundPastPerformanceAbstract 
Bar Chart and Performance Table [Heading]rr_BarChartAndPerformanceTableHeadingPERFORMANCE 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 Past Does Not Indicate Future [Text]rr_PerformancePastDoesNotIndicateFutureThe Fund’s past performance does not necessarily indicate how it will perform in the future.
Performance Table Closing [Text Block]rr_PerformanceTableClosingTextBlockUpdated performance information is available at janus.com/advisor/mutual-funds or by calling 1-877-335-2687.
Performance Availability Website Address [Text]rr_PerformanceAvailabilityWebSiteAddressjanus.com/advisor/mutual-funds
Performance Availability Phone [Text]rr_PerformanceAvailabilityPhone1-877-335-2687
Annual Total Returnsrr_BarChartTableAbstract 
Bar Chart [Heading]rr_BarChartHeadingAnnual Total Returns for Class T Shares (calendar year-end)
Bar Chart Closing [Text Block]rr_BarChartClosingTextBlock

Best Quarter:  First Quarter 2001  1.31%          Worst Quarter:  Fourth Quarter 2010  0.00%

Year to Date Return, Labelrr_YearToDateReturnLabelThe Fund’s year-to-date return as of the calendar quarter ended September 30, 2011 was 0.00%.
Bar Chart, Year to Date Return, Daterr_BarChartYearToDateReturnDateSep. 30, 2011
Bar Chart, Year to Date Returnrr_BarChartYearToDateReturn0.00%
Average Annual Total Returnsrr_AverageAnnualReturnAbstract 
Captionrr_AverageAnnualReturnCaptionAverage Annual Total Returns (periods ended 12/31/10)
Money Market Seven Day Yield, Caption [Text]rr_MoneyMarketSevenDayYieldCaptionThe 7-day yield on December 31, 2010 was 0.00% for Janus Government Money Market Fund.
Money Market Seven Day Yieldrr_MoneyMarketSevenDayYield0.00%
Janus Government Money Market Fund | Class T Shares | Class T
 
ANNUAL FUND OPERATING EXPENSESrr_OperatingExpensesAbstract 
Operating Expenses Column [Text]rr_OperatingExpensesColumnNameClass T
Management Feesrr_ManagementFeesOverAssets0.20%
Other Expensesrr_OtherExpensesOverAssets0.54%
Total Annual Fund Operating Expensesrr_ExpensesOverAssets0.74%
EXAMPLE:rr_ExpenseExampleAbstract 
Expense Example, By Year, Column [Text]rr_ExpenseExampleByYearColumnNameClass T Shares
1 Yearrr_ExpenseExampleYear0176
3 Yearsrr_ExpenseExampleYear03237
5 Yearsrr_ExpenseExampleYear05411
10 Yearsrr_ExpenseExampleYear10918
Annual Total Returnsrr_BarChartTableAbstract 
2001rr_AnnualReturn20013.73%
2002rr_AnnualReturn20021.33%
2003rr_AnnualReturn20030.65%
2004rr_AnnualReturn20040.85%
2005rr_AnnualReturn20052.70%
2006rr_AnnualReturn20064.52%
2007rr_AnnualReturn20074.66%
2008rr_AnnualReturn20081.83%
2009rr_AnnualReturn20090.01%
2010rr_AnnualReturn20100.02%
Highest Quarterly Return, Labelrr_HighestQuarterlyReturnLabelBest Quarter:
Highest Quarterly Return, Daterr_BarChartHighestQuarterlyReturnDateMar. 31, 2001
Highest Quarterly Returnrr_BarChartHighestQuarterlyReturn1.31%
Lowest Quarterly Return, Labelrr_LowestQuarterlyReturnLabelWorst Quarter:
Lowest Quarterly Return, Daterr_BarChartLowestQuarterlyReturnDateDec. 31, 2010
Lowest Quarterly Returnrr_BarChartLowestQuarterlyReturn0.00%
Janus Government Money Market Fund | Class T Shares | Return Before Taxes | Class T
 
Average Annual Total Returnsrr_AverageAnnualReturnAbstract 
Columnrr_AverageAnnualReturnColumnNameClass T Shares
Labelrr_AverageAnnualReturnLabelReturn Before Taxes
1 Yearrr_AverageAnnualReturnYear010.02%
5 Yearsrr_AverageAnnualReturnYear052.19%
10 Yearsrr_AverageAnnualReturnYear102.02%
Since Inceptionrr_AverageAnnualReturnSinceInception3.18%
Inception Daterr_AverageAnnualReturnInceptionDateFeb. 14, 1995
Janus Money Market Fund | Class D Shares
 
Risk/Return:rr_RiskReturnAbstract 
Risk/Return [Heading]rr_RiskReturnHeadingFUND SUMMARY Janus Money Market Fund
Objective [Heading]rr_ObjectiveHeadingINVESTMENT OBJECTIVES
Objective, Primary [Text Block]rr_ObjectivePrimaryTextBlockJanus Money Market Fund seeks capital preservation and liquidity
Objective, Secondary [Text Block]rr_ObjectiveSecondaryTextBlockwith current income as a secondary objective.
FEES AND EXPENSES OF THE FUNDjif277751_FundFeesAndExpensesAbstract 
Expense [Heading]rr_ExpenseHeadingFEES AND EXPENSES OF THE FUND
Expense Narrative [Text Block]rr_ExpenseNarrativeTextBlockThis table describes the fees and expenses that you may pay if you buy and hold Shares of the Fund.
ANNUAL FUND OPERATING EXPENSESrr_OperatingExpensesAbstract 
Operating Expenses Caption [Text]rr_OperatingExpensesCaptionANNUAL FUND OPERATING EXPENSES (expenses that you pay each year as a percentage of the value of your investment)
EXAMPLE:rr_ExpenseExampleAbstract 
Expense Example [Heading]rr_ExpenseExampleHeadingEXAMPLE:
Expense Example Narrative [Text Block]rr_ExpenseExampleNarrativeTextBlockThe 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 [Heading]rr_ExpenseExampleByYearHeadingThe 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:
Principal Investment Strategiesjif277751_PrincipalInvestmentStrategiesAbstract 
Strategy [Heading]rr_StrategyHeadingPRINCIPAL 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

Principal Investment Risksjif277751_PrincipalInvestmentRisksAbstract 
Risk [Heading]rr_RiskHeadingPRINCIPAL 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_RiskMoneyMarketFundMoney 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 INFORMATIONjif277751_FundPastPerformanceAbstract 
Bar Chart and Performance Table [Heading]rr_BarChartAndPerformanceTableHeadingPERFORMANCE 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 Past Does Not Indicate Future [Text]rr_PerformancePastDoesNotIndicateFutureThe Fund’s past performance does not necessarily indicate how it will perform in the future.
Performance Table Closing [Text Block]rr_PerformanceTableClosingTextBlockUpdated performance information is available at janus.com/allfunds or by calling 1-800-525-3713.
Performance Availability Website Address [Text]rr_PerformanceAvailabilityWebSiteAddressjanus.com/allfunds
Performance Availability Phone [Text]rr_PerformanceAvailabilityPhone1-800-525-3713.
Annual Total Returnsrr_BarChartTableAbstract 
Bar Chart [Heading]rr_BarChartHeadingAnnual Total Returns for Class D Shares (calendar year-end)
Bar Chart Closing [Text Block]rr_BarChartClosingTextBlock

Best Quarter:  First Quarter 2001  1.33%          Worst Quarter:  Fourth Quarter 2010  0.00%

Year to Date Return, Labelrr_YearToDateReturnLabelThe Fund’s year-to-date return as of the calendar quarter ended September 30, 2011 was 0.00%.
Bar Chart, Year to Date Return, Daterr_BarChartYearToDateReturnDateSep. 30, 2011
Bar Chart, Year to Date Returnrr_BarChartYearToDateReturn0.00%
Average Annual Total Returnsrr_AverageAnnualReturnAbstract 
Captionrr_AverageAnnualReturnCaptionAverage Annual Total Returns (periods ended 12/31/10)
Money Market Seven Day Yield, Caption [Text]rr_MoneyMarketSevenDayYieldCaptionThe 7-day yield on December 31, 2010 was 0.00% for Janus Money Market Fund.
Money Market Seven Day Yieldrr_MoneyMarketSevenDayYield0.00%
Janus Money Market Fund | Class D Shares | Class D
 
ANNUAL FUND OPERATING EXPENSESrr_OperatingExpensesAbstract 
Operating Expenses Column [Text]rr_OperatingExpensesColumnNameClass D
Management Feesrr_ManagementFeesOverAssets0.20%
Other Expensesrr_OtherExpensesOverAssets0.47%
Total Annual Fund Operating Expensesrr_ExpensesOverAssets0.67%
EXAMPLE:rr_ExpenseExampleAbstract 
Expense Example, By Year, Column [Text]rr_ExpenseExampleByYearColumnNameClass D Shares
1 Yearrr_ExpenseExampleYear0168
3 Yearsrr_ExpenseExampleYear03214
5 Yearsrr_ExpenseExampleYear05373
10 Yearsrr_ExpenseExampleYear10835
Annual Total Returnsrr_BarChartTableAbstract 
2001rr_AnnualReturn20013.78%
2002rr_AnnualReturn20021.38%
2003rr_AnnualReturn20030.71%
2004rr_AnnualReturn20040.93%
2005rr_AnnualReturn20052.77%
2006rr_AnnualReturn20064.60%
2007rr_AnnualReturn20074.86%
2008rr_AnnualReturn20082.09%
2009rr_AnnualReturn20090.07%
2010rr_AnnualReturn20100.01%
Highest Quarterly Return, Labelrr_HighestQuarterlyReturnLabelBest Quarter:
Highest Quarterly Return, Daterr_BarChartHighestQuarterlyReturnDateMar. 31, 2001
Highest Quarterly Returnrr_BarChartHighestQuarterlyReturn1.33%
Lowest Quarterly Return, Labelrr_LowestQuarterlyReturnLabelWorst Quarter:
Lowest Quarterly Return, Daterr_BarChartLowestQuarterlyReturnDateDec. 31, 2010
Lowest Quarterly Returnrr_BarChartLowestQuarterlyReturn0.00%
Janus Money Market Fund | Class D Shares | Return Before Taxes | Class D
 
Average Annual Total Returnsrr_AverageAnnualReturnAbstract 
Columnrr_AverageAnnualReturnColumnNameClass D Shares
Labelrr_AverageAnnualReturnLabelReturn Before Taxes
1 Yearrr_AverageAnnualReturnYear010.01%
5 Yearsrr_AverageAnnualReturnYear052.30%
10 Yearsrr_AverageAnnualReturnYear102.10%
Since Inceptionrr_AverageAnnualReturnSinceInception3.28%
Inception Daterr_AverageAnnualReturnInceptionDateFeb. 14, 1995
Janus Money Market Fund | Class T Shares
 
Risk/Return:rr_RiskReturnAbstract 
Risk/Return [Heading]rr_RiskReturnHeadingFUND SUMMARY Janus Money Market Fund
Objective [Heading]rr_ObjectiveHeadingINVESTMENT OBJECTIVES
Objective, Primary [Text Block]rr_ObjectivePrimaryTextBlockJanus Money Market Fund seeks capital preservation and liquidity
Objective, Secondary [Text Block]rr_ObjectiveSecondaryTextBlockwith current income as a secondary objective.
FEES AND EXPENSES OF THE FUNDjif277751_FundFeesAndExpensesAbstract 
Expense [Heading]rr_ExpenseHeadingFEES AND EXPENSES OF THE FUND
Expense Narrative [Text Block]rr_ExpenseNarrativeTextBlockThis table describes the fees and expenses that you may pay if you buy and hold Shares of the Fund.
ANNUAL FUND OPERATING EXPENSESrr_OperatingExpensesAbstract 
Operating Expenses Caption [Text]rr_OperatingExpensesCaptionANNUAL FUND OPERATING EXPENSES (expenses that you pay each year as a percentage of the value of your investment)
EXAMPLE:rr_ExpenseExampleAbstract 
Expense Example [Heading]rr_ExpenseExampleHeadingEXAMPLE:
Expense Example Narrative [Text Block]rr_ExpenseExampleNarrativeTextBlockThe 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 [Heading]rr_ExpenseExampleByYearHeadingThe 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:
Principal Investment Strategiesjif277751_PrincipalInvestmentStrategiesAbstract 
Strategy [Heading]rr_StrategyHeadingPRINCIPAL 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

Principal Investment Risksjif277751_PrincipalInvestmentRisksAbstract 
Risk [Heading]rr_RiskHeadingPRINCIPAL 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_RiskMoneyMarketFundMoney 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 INFORMATIONjif277751_FundPastPerformanceAbstract 
Bar Chart and Performance Table [Heading]rr_BarChartAndPerformanceTableHeadingPERFORMANCE 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 Past Does Not Indicate Future [Text]rr_PerformancePastDoesNotIndicateFutureThe Fund’s past performance does not necessarily indicate how it will perform in the future.
Performance Table Closing [Text Block]rr_PerformanceTableClosingTextBlockUpdated performance information is available at janus.com/advisor/mutual-funds or by calling 1-877-335-2687.
Performance Availability Website Address [Text]rr_PerformanceAvailabilityWebSiteAddressjanus.com/advisor/mutual-funds
Performance Availability Phone [Text]rr_PerformanceAvailabilityPhone1-877-335-2687
Annual Total Returnsrr_BarChartTableAbstract 
Bar Chart [Heading]rr_BarChartHeadingAnnual Total Returns for Class T Shares (calendar year-end)
Bar Chart Closing [Text Block]rr_BarChartClosingTextBlock

Best Quarter:  First Quarter 2001  1.33%          Worst Quarter:  Fourth Quarter 2010  0.00%

Year to Date Return, Labelrr_YearToDateReturnLabelThe Fund’s year-to-date return as of the calendar quarter ended September 30, 2011 was 0.00%.
Bar Chart, Year to Date Return, Daterr_BarChartYearToDateReturnDateSep. 30, 2011
Bar Chart, Year to Date Returnrr_BarChartYearToDateReturn0.00%
Average Annual Total Returnsrr_AverageAnnualReturnAbstract 
Captionrr_AverageAnnualReturnCaptionAverage Annual Total Returns (periods ended 12/31/10)
Money Market Seven Day Yield, Caption [Text]rr_MoneyMarketSevenDayYieldCaptionThe 7-day yield on December 31, 2010 was 0.00% for Janus Money Market Fund.
Money Market Seven Day Yieldrr_MoneyMarketSevenDayYield0.00%
Janus Money Market Fund | Class T Shares | Class T
 
ANNUAL FUND OPERATING EXPENSESrr_OperatingExpensesAbstract 
Operating Expenses Column [Text]rr_OperatingExpensesColumnNameClass T
Management Feesrr_ManagementFeesOverAssets0.20%
Other Expensesrr_OtherExpensesOverAssets0.49%
Total Annual Fund Operating Expensesrr_ExpensesOverAssets0.69%
EXAMPLE:rr_ExpenseExampleAbstract 
Expense Example, By Year, Column [Text]rr_ExpenseExampleByYearColumnNameClass T Shares
1 Yearrr_ExpenseExampleYear0170
3 Yearsrr_ExpenseExampleYear03221
5 Yearsrr_ExpenseExampleYear05384
10 Yearsrr_ExpenseExampleYear10859
Annual Total Returnsrr_BarChartTableAbstract 
2001rr_AnnualReturn20013.78%
2002rr_AnnualReturn20021.38%
2003rr_AnnualReturn20030.71%
2004rr_AnnualReturn20040.93%
2005rr_AnnualReturn20052.77%
2006rr_AnnualReturn20064.60%
2007rr_AnnualReturn20074.86%
2008rr_AnnualReturn20082.09%
2009rr_AnnualReturn20090.07%
2010rr_AnnualReturn20100.01%
Highest Quarterly Return, Labelrr_HighestQuarterlyReturnLabelBest Quarter:
Highest Quarterly Return, Daterr_BarChartHighestQuarterlyReturnDateMar. 31, 2001
Highest Quarterly Returnrr_BarChartHighestQuarterlyReturn1.33%
Lowest Quarterly Return, Labelrr_LowestQuarterlyReturnLabelWorst Quarter:
Lowest Quarterly Return, Daterr_BarChartLowestQuarterlyReturnDateDec. 31, 2010
Lowest Quarterly Returnrr_BarChartLowestQuarterlyReturn0.00%
Janus Money Market Fund | Class T Shares | Return Before Taxes | Class T
 
Average Annual Total Returnsrr_AverageAnnualReturnAbstract 
Columnrr_AverageAnnualReturnColumnNameClass T Shares
Labelrr_AverageAnnualReturnLabelReturn Before Taxes
1 Yearrr_AverageAnnualReturnYear010.01%
5 Yearsrr_AverageAnnualReturnYear052.30%
10 Yearsrr_AverageAnnualReturnYear102.10%
Since Inceptionrr_AverageAnnualReturnSinceInception3.28%
Inception Daterr_AverageAnnualReturnInceptionDateFeb. 14, 1995
Perkins Large Cap Value Fund | Class A, C, S, I, T Shares
 
Risk/Return:rr_RiskReturnAbstract 
Risk/Return [Heading]rr_RiskReturnHeadingFUND SUMMARY Perkins Large Cap Value Fund
Objective [Heading]rr_ObjectiveHeadingINVESTMENT OBJECTIVE
Objective, Primary [Text Block]rr_ObjectivePrimaryTextBlockPerkins Large Cap Value Fund seeks capital appreciation.
FEES AND EXPENSES OF THE FUNDjif277751_FundFeesAndExpensesAbstract 
Expense [Heading]rr_ExpenseHeadingFEES AND EXPENSES OF THE FUND
Expense Narrative [Text Block]rr_ExpenseNarrativeTextBlockThis 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.
Expense Breakpoint Discountsjif277751_ExpenseBreakpointDiscountsAbstract 
Expense Breakpoint Discounts [Text]rr_ExpenseBreakpointDiscountsFor 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 48 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_ExpenseBreakpointMinimumInvestmentRequiredAmount50,000
SHAREHOLDER FEESrr_ShareholderFeesAbstract 
Shareholder Fees Caption [Text]rr_ShareholderFeesCaptionSHAREHOLDER FEES (fees paid directly from your investment)
ANNUAL FUND OPERATING EXPENSESrr_OperatingExpensesAbstract 
Operating Expenses Caption [Text]rr_OperatingExpensesCaptionANNUAL 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 Terminationrr_FeeWaiverOrReimbursementOverAssetsDateOfTerminationNovember 1, 2012
EXAMPLE:rr_ExpenseExampleAbstract 
Expense Example [Heading]rr_ExpenseExampleHeadingEXAMPLE:
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 [Heading]rr_ExpenseExampleByYearHeadingThe 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 by, Year, Caption [Text]rr_ExpenseExampleByYearCaptionIf Shares are redeemed:
Expense Example, No Redemption:rr_ExpenseExampleNoRedemptionAbstract 
Expense Example, No Redemption, By Year, Caption [Text]rr_ExpenseExampleNoRedemptionByYearCaptionIf Shares are not redeemed:
Portfolio Turnover:jif277751_PortfolioTurnoverAltAbstract 
Portfolio Turnover [Heading]rr_PortfolioTurnoverHeadingPortfolio Turnover:
Portfolio Turnover [Text Block]rr_PortfolioTurnoverTextBlockThe 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 period, the Fund’s portfolio turnover rate was 43% of the average value of its portfolio.
Portfolio Turnover, Raterr_PortfolioTurnoverRate43.00%
Principal Investment Strategiesjif277751_PrincipalInvestmentStrategiesAbstract 
Strategy [Heading]rr_StrategyHeadingPRINCIPAL 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, 2011, they ranged from approximately $1.4 billion to $400 billion, and the median market capitalization was $5 billion. The Fund may 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 assets in securities of companies having market capitalizations outside of the aforementioned market capitalization ranges or in cash or cash equivalents.

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 an underlying asset, such as equity securities, bonds, 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. For more information on the Fund’s use of derivatives, refer to the Fund’s shareholder reports and Form N-Q reports, which are filed with the Securities and Exchange Commission.

Principal Investment Risksjif277751_PrincipalInvestmentRisksAbstract 
Risk [Heading]rr_RiskHeadingPRINCIPAL 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.

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, including 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. 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.

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 can be substantially greater than the derivative’s original cost, and can therefore involve 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_RiskLoseMoneyThe biggest risk is that the Fund’s returns will vary, and you could lose money.
Risk Not Insured Depository Institution [Text]rr_RiskNotInsuredDepositoryInstitutionAn 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 INFORMATIONjif277751_FundPastPerformanceAbstract 
Bar Chart and Performance Table [Heading]rr_BarChartAndPerformanceTableHeadingPERFORMANCE 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.

• 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.

Bar Chart Does Not Reflect Sales Loads [Text]rr_BarChartDoesNotReflectSalesLoadsThe 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.
Performance Additional Market Index [Text]rr_PerformanceAdditionalMarketIndexThe 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 Past Does Not Indicate Future [Text]rr_PerformancePastDoesNotIndicateFutureThe Fund’s past performance (before and after taxes) does not necessarily indicate how it will perform in the future.
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.
Performance Availability Website Address [Text]rr_PerformanceAvailabilityWebSiteAddressjanus.com/advisor/mutual-funds
Performance Availability Phone [Text]rr_PerformanceAvailabilityPhone1-877-335-2687
Annual Total Returnsrr_BarChartTableAbstract 
Bar Chart [Heading]rr_BarChartHeadingAnnual Total Returns for Class I Shares (calendar year-end)
Bar Chart Closing [Text Block]rr_BarChartClosingTextBlock

Best Quarter:  Second Quarter 2009  15.40%          Worst Quarter:  Second Quarter 2010 -10.99%

Year to Date Return, Labelrr_YearToDateReturnLabelThe Fund's year-to-date return as of the calendar quarter ended September 30, 2011 was -10.25%.
Bar Chart, Year to Date Return, Daterr_BarChartYearToDateReturnDateSep. 30, 2011
Bar Chart, Year to Date Returnrr_BarChartYearToDateReturn(10.25%)
Average Annual Total Returnsrr_AverageAnnualReturnAbstract 
Captionrr_AverageAnnualReturnCaptionAverage Annual Total Returns (periods ended 12/31/10)
Performance Table Narrativerr_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 Uses Highest Federal Raterr_PerformanceTableUsesHighestFederalRateAfter-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 Deferredrr_PerformanceTableNotRelevantToTaxDeferredActual 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_PerformanceTableOneClassOfAfterTaxShownAfter-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.
Perkins Large Cap Value Fund | Class A, C, S, I, T Shares | Class A
 
SHAREHOLDER FEESrr_ShareholderFeesAbstract 
Shareholder Fees Column [Text]rr_ShareholderFeesColumnNameClass A
Maximum Sales Charge (load) Imposed on Purchases (as a percentage of offering price)rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice5.75%
Maximum Deferred Sales Charge (load) (as a percentage of the lower of original purchase price or redemption proceeds)rr_MaximumDeferredSalesChargeOverOther none
ANNUAL FUND OPERATING EXPENSESrr_OperatingExpensesAbstract 
Operating Expenses Column [Text]rr_OperatingExpensesColumnNameClass A
Management Feesrr_ManagementFeesOverAssets0.66%
Distribution/Service (12b-1) Feesrr_DistributionAndService12b1FeesOverAssets0.25%
Other Expensesrr_OtherExpensesOverAssets0.28%
Total Annual Fund Operating Expensesrr_ExpensesOverAssets1.19%[27]
EXAMPLE:rr_ExpenseExampleAbstract 
Expense Example, By Year, Column [Text]rr_ExpenseExampleByYearColumnNameClass A Shares
1 Yearrr_ExpenseExampleYear01689
3 Yearsrr_ExpenseExampleYear03931
5 Yearsrr_ExpenseExampleYear051,192
10 Yearsrr_ExpenseExampleYear101,935
Expense Example, No Redemption:rr_ExpenseExampleNoRedemptionAbstract 
Expense Example, No Redemption, By Year, Column [Text]rr_ExpenseExampleNoRedemptionByYearColumnNameClass A Shares
1 Yearrr_ExpenseExampleNoRedemptionYear01689
3 Yearsrr_ExpenseExampleNoRedemptionYear03931
5 Yearsrr_ExpenseExampleNoRedemptionYear051,192
10 Yearsrr_ExpenseExampleNoRedemptionYear101,935
Perkins Large Cap Value Fund | Class A, C, S, I, T Shares | Class C
 
SHAREHOLDER FEESrr_ShareholderFeesAbstract 
Shareholder Fees Column [Text]rr_ShareholderFeesColumnNameClass 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_MaximumDeferredSalesChargeOverOther1.00%
ANNUAL FUND OPERATING EXPENSESrr_OperatingExpensesAbstract 
Operating Expenses Column [Text]rr_OperatingExpensesColumnNameClass C
Management Feesrr_ManagementFeesOverAssets0.66%
Distribution/Service (12b-1) Feesrr_DistributionAndService12b1FeesOverAssets1.00%
Other Expensesrr_OtherExpensesOverAssets0.31%
Total Annual Fund Operating Expensesrr_ExpensesOverAssets1.97%[27]
EXAMPLE:rr_ExpenseExampleAbstract 
Expense Example, By Year, Column [Text]rr_ExpenseExampleByYearColumnNameClass C Shares
1 Yearrr_ExpenseExampleYear01300
3 Yearsrr_ExpenseExampleYear03618
5 Yearsrr_ExpenseExampleYear051,062
10 Yearsrr_ExpenseExampleYear102,296
Expense Example, No Redemption:rr_ExpenseExampleNoRedemptionAbstract 
Expense Example, No Redemption, By Year, Column [Text]rr_ExpenseExampleNoRedemptionByYearColumnNameClass C Shares
1 Yearrr_ExpenseExampleNoRedemptionYear01200
3 Yearsrr_ExpenseExampleNoRedemptionYear03618
5 Yearsrr_ExpenseExampleNoRedemptionYear051,062
10 Yearsrr_ExpenseExampleNoRedemptionYear102,296
Perkins Large Cap Value Fund | Class A, C, S, I, T Shares | Class S
 
SHAREHOLDER FEESrr_ShareholderFeesAbstract 
Shareholder Fees Column [Text]rr_ShareholderFeesColumnNameClass 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
ANNUAL FUND OPERATING EXPENSESrr_OperatingExpensesAbstract 
Operating Expenses Column [Text]rr_OperatingExpensesColumnNameClass S
Management Feesrr_ManagementFeesOverAssets0.66%
Distribution/Service (12b-1) Feesrr_DistributionAndService12b1FeesOverAssets0.25%
Other Expensesrr_OtherExpensesOverAssets0.44%
Total Annual Fund Operating Expensesrr_ExpensesOverAssets1.35%[27]
EXAMPLE:rr_ExpenseExampleAbstract 
Expense Example, By Year, Column [Text]rr_ExpenseExampleByYearColumnNameClass S Shares
1 Yearrr_ExpenseExampleYear01137
3 Yearsrr_ExpenseExampleYear03428
5 Yearsrr_ExpenseExampleYear05739
10 Yearsrr_ExpenseExampleYear101,624
Expense Example, No Redemption:rr_ExpenseExampleNoRedemptionAbstract 
Expense Example, No Redemption, By Year, Column [Text]rr_ExpenseExampleNoRedemptionByYearColumnNameClass S Shares
1 Yearrr_ExpenseExampleNoRedemptionYear01137
3 Yearsrr_ExpenseExampleNoRedemptionYear03428
5 Yearsrr_ExpenseExampleNoRedemptionYear05739
10 Yearsrr_ExpenseExampleNoRedemptionYear101,624
Perkins Large Cap Value Fund | Class A, C, S, I, T Shares | Class I
 
SHAREHOLDER FEESrr_ShareholderFeesAbstract 
Shareholder Fees Column [Text]rr_ShareholderFeesColumnNameClass 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
ANNUAL FUND OPERATING EXPENSESrr_OperatingExpensesAbstract 
Operating Expenses Column [Text]rr_OperatingExpensesColumnNameClass I
Management Feesrr_ManagementFeesOverAssets0.66%
Distribution/Service (12b-1) Feesrr_DistributionAndService12b1FeesOverAssets none
Other Expensesrr_OtherExpensesOverAssets0.19%
Total Annual Fund Operating Expensesrr_ExpensesOverAssets0.85%[27]
EXAMPLE:rr_ExpenseExampleAbstract 
Expense Example, By Year, Column [Text]rr_ExpenseExampleByYearColumnNameClass I Shares
1 Yearrr_ExpenseExampleYear0187
3 Yearsrr_ExpenseExampleYear03271
5 Yearsrr_ExpenseExampleYear05471
10 Yearsrr_ExpenseExampleYear101,049
Expense Example, No Redemption:rr_ExpenseExampleNoRedemptionAbstract 
Expense Example, No Redemption, By Year, Column [Text]rr_ExpenseExampleNoRedemptionByYearColumnNameClass I Shares
1 Yearrr_ExpenseExampleNoRedemptionYear0187
3 Yearsrr_ExpenseExampleNoRedemptionYear03271
5 Yearsrr_ExpenseExampleNoRedemptionYear05471
10 Yearsrr_ExpenseExampleNoRedemptionYear101,049
Annual Total Returnsrr_BarChartTableAbstract 
2009rr_AnnualReturn200925.15%
2010rr_AnnualReturn201012.19%
Highest Quarterly Return, Labelrr_HighestQuarterlyReturnLabelBest Quarter:
Highest Quarterly Return, Daterr_BarChartHighestQuarterlyReturnDateJun. 30, 2009
Highest Quarterly Returnrr_BarChartHighestQuarterlyReturn15.40%
Lowest Quarterly Return, Labelrr_LowestQuarterlyReturnLabelWorst Quarter:
Lowest Quarterly Return, Daterr_BarChartLowestQuarterlyReturnDateJun. 30, 2010
Lowest Quarterly Returnrr_BarChartLowestQuarterlyReturn(10.99%)
Perkins Large Cap Value Fund | Class A, C, S, I, T Shares | Class T
 
SHAREHOLDER FEESrr_ShareholderFeesAbstract 
Shareholder Fees Column [Text]rr_ShareholderFeesColumnNameClass 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
ANNUAL FUND OPERATING EXPENSESrr_OperatingExpensesAbstract 
Operating Expenses Column [Text]rr_OperatingExpensesColumnNameClass T
Management Feesrr_ManagementFeesOverAssets0.66%
Distribution/Service (12b-1) Feesrr_DistributionAndService12b1FeesOverAssets none
Other Expensesrr_OtherExpensesOverAssets0.40%
Total Annual Fund Operating Expensesrr_ExpensesOverAssets1.06%[27]
EXAMPLE:rr_ExpenseExampleAbstract 
Expense Example, By Year, Column [Text]rr_ExpenseExampleByYearColumnNameClass T Shares
1 Yearrr_ExpenseExampleYear01108
3 Yearsrr_ExpenseExampleYear03337
5 Yearsrr_ExpenseExampleYear05585
10 Yearsrr_ExpenseExampleYear101,294
Expense Example, No Redemption:rr_ExpenseExampleNoRedemptionAbstract 
Expense Example, No Redemption, By Year, Column [Text]rr_ExpenseExampleNoRedemptionByYearColumnNameClass T Shares
1 Yearrr_ExpenseExampleNoRedemptionYear01108
3 Yearsrr_ExpenseExampleNoRedemptionYear03337
5 Yearsrr_ExpenseExampleNoRedemptionYear05585
10 Yearsrr_ExpenseExampleNoRedemptionYear101,294
Perkins Large Cap Value Fund | Class A, C, S, I, T Shares | Return Before Taxes | Class A
 
Average Annual Total Returnsrr_AverageAnnualReturnAbstract 
Columnrr_AverageAnnualReturnColumnNameClass A Shares
Labelrr_AverageAnnualReturnLabelReturn Before Taxes[3]
1 Yearrr_AverageAnnualReturnYear015.48%
Since Inceptionrr_AverageAnnualReturnSinceInception14.75%
Inception Daterr_AverageAnnualReturnInceptionDateDec. 31, 2008
Perkins Large Cap Value Fund | Class A, C, S, I, T Shares | Return Before Taxes | Class C
 
Average Annual Total Returnsrr_AverageAnnualReturnAbstract 
Columnrr_AverageAnnualReturnColumnNameClass C Shares
Labelrr_AverageAnnualReturnLabelReturn Before Taxes[4]
1 Yearrr_AverageAnnualReturnYear019.89%
Since Inceptionrr_AverageAnnualReturnSinceInception17.28%
Inception Daterr_AverageAnnualReturnInceptionDateDec. 31, 2008
Perkins Large Cap Value Fund | Class A, C, S, I, T Shares | Return Before Taxes | Class S
 
Average Annual Total Returnsrr_AverageAnnualReturnAbstract 
Columnrr_AverageAnnualReturnColumnNameClass S Shares
Labelrr_AverageAnnualReturnLabelReturn Before Taxes
1 Yearrr_AverageAnnualReturnYear0111.65%
Since Inceptionrr_AverageAnnualReturnSinceInception17.93%
Inception Daterr_AverageAnnualReturnInceptionDateDec. 31, 2008
Perkins Large Cap Value Fund | Class A, C, S, I, T Shares | Return Before Taxes | Class I
 
Average Annual Total Returnsrr_AverageAnnualReturnAbstract 
Columnrr_AverageAnnualReturnColumnNameClass I Shares
Labelrr_AverageAnnualReturnLabelReturn Before Taxes
1 Yearrr_AverageAnnualReturnYear0112.19%
Since Inceptionrr_AverageAnnualReturnSinceInception18.49%
Inception Daterr_AverageAnnualReturnInceptionDateDec. 31, 2008
Perkins Large Cap Value Fund | Class A, C, S, I, T Shares | Return Before Taxes | Class T
 
Average Annual Total Returnsrr_AverageAnnualReturnAbstract 
Columnrr_AverageAnnualReturnColumnNameClass T Shares
Labelrr_AverageAnnualReturnLabelReturn Before Taxes
1 Yearrr_AverageAnnualReturnYear0111.97%
Since Inceptionrr_AverageAnnualReturnSinceInception17.96%
Inception Daterr_AverageAnnualReturnInceptionDateDec. 31, 2008
Perkins Large Cap Value Fund | Class A, C, S, I, T Shares | Return After Taxes on Distributions | Class I
 
Average Annual Total Returnsrr_AverageAnnualReturnAbstract 
Columnrr_AverageAnnualReturnColumnNameClass I Shares
Labelrr_AverageAnnualReturnLabelReturn After Taxes on Distributions
1 Yearrr_AverageAnnualReturnYear0111.39%
Since Inceptionrr_AverageAnnualReturnSinceInception17.97%
Inception Daterr_AverageAnnualReturnInceptionDateDec. 31, 2008
Perkins Large Cap Value Fund | Class A, C, S, I, T Shares | Return After Taxes on Distributions and Sale of Fund Shares | Class I
 
Average Annual Total Returnsrr_AverageAnnualReturnAbstract 
Columnrr_AverageAnnualReturnColumnNameClass I Shares
Labelrr_AverageAnnualReturnLabelReturn After Taxes on Distributions and Sale of Fund Shares[5]
1 Yearrr_AverageAnnualReturnYear018.42%
Since Inceptionrr_AverageAnnualReturnSinceInception15.73%
Inception Daterr_AverageAnnualReturnInceptionDateDec. 31, 2008
Perkins Large Cap Value Fund | Class A, C, S, I, T Shares | Russell 1000® Value Index
 
Average Annual Total Returnsrr_AverageAnnualReturnAbstract 
Labelrr_AverageAnnualReturnLabelRussell 1000® Value Index
Index No Deduction for Fees, Expenses, Taxes [Text]rr_IndexNoDeductionForFeesExpensesTaxes(reflects no deduction for expenses, fees, or taxes)
1 Yearrr_AverageAnnualReturnYear0115.51%
Since Inceptionrr_AverageAnnualReturnSinceInception17.58%
Inception Daterr_AverageAnnualReturnInceptionDateDec. 31, 2008
Perkins Large Cap Value Fund | Class D Shares
 
Risk/Return:rr_RiskReturnAbstract 
Risk/Return [Heading]rr_RiskReturnHeadingFUND SUMMARY Perkins Large Cap Value Fund
Objective [Heading]rr_ObjectiveHeadingINVESTMENT OBJECTIVE
Objective, Primary [Text Block]rr_ObjectivePrimaryTextBlockPerkins Large Cap Value Fund seeks capital appreciation.
FEES AND EXPENSES OF THE FUNDjif277751_FundFeesAndExpensesAbstract 
Expense [Heading]rr_ExpenseHeadingFEES AND EXPENSES OF THE FUND
Expense Narrative [Text Block]rr_ExpenseNarrativeTextBlockThis table describes the fees and expenses that you may pay if you buy and hold Shares of the Fund.
ANNUAL FUND OPERATING EXPENSESrr_OperatingExpensesAbstract 
Operating Expenses Caption [Text]rr_OperatingExpensesCaptionANNUAL 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 Terminationrr_FeeWaiverOrReimbursementOverAssetsDateOfTerminationNovember 1, 2012
EXAMPLE:rr_ExpenseExampleAbstract 
Expense Example [Heading]rr_ExpenseExampleHeadingEXAMPLE:
Expense Example Narrative [Text Block]rr_ExpenseExampleNarrativeTextBlockThe 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 [Heading]rr_ExpenseExampleByYearHeadingThe 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:
Portfolio Turnover:jif277751_PortfolioTurnoverAltAbstract 
Portfolio Turnover [Heading]rr_PortfolioTurnoverHeadingPortfolio Turnover:
Portfolio Turnover [Text Block]rr_PortfolioTurnoverTextBlockThe 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 period, the Fund’s portfolio turnover rate was 43% of the average value of its portfolio.
Portfolio Turnover, Raterr_PortfolioTurnoverRate43.00%
Principal Investment Strategiesjif277751_PrincipalInvestmentStrategiesAbstract 
Strategy [Heading]rr_StrategyHeadingPRINCIPAL 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, 2011, they ranged from approximately $1.4 billion to $400 billion, and the median market capitalization was $5 billion. The Fund may 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 assets in securities of companies having market capitalizations outside of the aforementioned market capitalization ranges or in cash or cash equivalents.

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 an underlying asset, such as equity securities, bonds, 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. For more information on the Fund’s use of derivatives, refer to the Fund’s shareholder reports and Form N-Q reports, which are filed with the Securities and Exchange Commission.

Principal Investment Risksjif277751_PrincipalInvestmentRisksAbstract 
Risk [Heading]rr_RiskHeadingPRINCIPAL 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.

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, including 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. 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.

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 can be substantially greater than the derivative’s original cost, and can therefore involve 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_RiskLoseMoneyThe biggest risk is that the Fund’s returns will vary, and you could lose money.
Risk Not Insured Depository Institution [Text]rr_RiskNotInsuredDepositoryInstitutionAn 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 INFORMATIONjif277751_FundPastPerformanceAbstract 
Bar Chart and Performance Table [Heading]rr_BarChartAndPerformanceTableHeadingPERFORMANCE 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 December 31, 2009, 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_PerformanceAdditionalMarketIndexThe 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 Past Does Not Indicate Future [Text]rr_PerformancePastDoesNotIndicateFutureThe Fund’s past performance (before and after taxes) does not necessarily indicate how it will perform in the future.
Performance Table Closing [Text Block]rr_PerformanceTableClosingTextBlockUpdated performance information is available at janus.com/allfunds or by calling 1-800-525-3713.
Performance Availability Website Address [Text]rr_PerformanceAvailabilityWebSiteAddressjanus.com/allfunds
Performance Availability Phone [Text]rr_PerformanceAvailabilityPhone1-800-525-3713
Annual Total Returnsrr_BarChartTableAbstract 
Bar Chart [Heading]rr_BarChartHeadingAnnual 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: Second Quarter 2010 -10.92%

Year to Date Return, Labelrr_YearToDateReturnLabelThe Fund’s year-to-date return as of the calendar quarter ended September 30, 2011 was -10.33%.
Bar Chart, Year to Date Return, Daterr_BarChartYearToDateReturnDateSep. 30, 2011
Bar Chart, Year to Date Returnrr_BarChartYearToDateReturn(10.33%)
Average Annual Total Returnsrr_AverageAnnualReturnAbstract 
Captionrr_AverageAnnualReturnCaptionAverage Annual Total Returns (periods ended 12/31/10)
Performance Table Narrativerr_PerformanceTableNarrativeTextBlockAfter-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 Uses Highest Federal Raterr_PerformanceTableUsesHighestFederalRateAfter-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 Deferredrr_PerformanceTableNotRelevantToTaxDeferredActual 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.
Perkins Large Cap Value Fund | Class D Shares | Class D
 
ANNUAL FUND OPERATING EXPENSESrr_OperatingExpensesAbstract 
Operating Expenses Column [Text]rr_OperatingExpensesColumnNameClass D
Management Feesrr_ManagementFeesOverAssets0.66%
Other Expensesrr_OtherExpensesOverAssets0.27%
Total Annual Fund Operating Expensesrr_ExpensesOverAssets0.93%[28]
EXAMPLE:rr_ExpenseExampleAbstract 
Expense Example, By Year, Column [Text]rr_ExpenseExampleByYearColumnNameClass D Shares
1 Yearrr_ExpenseExampleYear0195
3 Yearsrr_ExpenseExampleYear03296
5 Yearsrr_ExpenseExampleYear05515
10 Yearsrr_ExpenseExampleYear101,143
Annual Total Returnsrr_BarChartTableAbstract 
2009rr_AnnualReturn200923.61%
2010rr_AnnualReturn201011.94%
Highest Quarterly Return, Labelrr_HighestQuarterlyReturnLabelBest Quarter:
Highest Quarterly Return, Daterr_BarChartHighestQuarterlyReturnDateJun. 30, 2009
Highest Quarterly Returnrr_BarChartHighestQuarterlyReturn15.02%
Lowest Quarterly Return, Labelrr_LowestQuarterlyReturnLabelWorst Quarter:
Lowest Quarterly Return, Daterr_BarChartLowestQuarterlyReturnDateJun. 30, 2010
Lowest Quarterly Returnrr_BarChartLowestQuarterlyReturn(10.92%)
Perkins Large Cap Value Fund | Class D Shares | Return Before Taxes | Class D
 
Average Annual Total Returnsrr_AverageAnnualReturnAbstract 
Columnrr_AverageAnnualReturnColumnNameClass D Shares
Labelrr_AverageAnnualReturnLabelReturn Before Taxes
1 Yearrr_AverageAnnualReturnYear0111.94%
Since Inceptionrr_AverageAnnualReturnSinceInception17.63%
Inception Daterr_AverageAnnualReturnInceptionDateDec. 31, 2008
Perkins Large Cap Value Fund | Class D Shares | Return After Taxes on Distributions | Class D
 
Average Annual Total Returnsrr_AverageAnnualReturnAbstract 
Columnrr_AverageAnnualReturnColumnNameClass D Shares
Labelrr_AverageAnnualReturnLabelReturn After Taxes on Distributions
1 Yearrr_AverageAnnualReturnYear0111.14%
Since Inceptionrr_AverageAnnualReturnSinceInception17.11%
Inception Daterr_AverageAnnualReturnInceptionDateDec. 31, 2008
Perkins Large Cap Value Fund | Class D Shares | Return After Taxes on Distributions and Sale of Fund Shares | Class D
 
Average Annual Total Returnsrr_AverageAnnualReturnAbstract 
Columnrr_AverageAnnualReturnColumnNameClass D Shares
Labelrr_AverageAnnualReturnLabelReturn After Taxes on Distributions and Sale of Fund Shares[5]
1 Yearrr_AverageAnnualReturnYear018.26%
Since Inceptionrr_AverageAnnualReturnSinceInception14.98%
Inception Daterr_AverageAnnualReturnInceptionDateDec. 31, 2008
Perkins Large Cap Value Fund | Class D Shares | Russell 1000® Value Index
 
Average Annual Total Returnsrr_AverageAnnualReturnAbstract 
Labelrr_AverageAnnualReturnLabelRussell 1000® Value Index
Index No Deduction for Fees, Expenses, Taxes [Text]rr_IndexNoDeductionForFeesExpensesTaxes(reflects no deduction for expenses, fees, or taxes)
1 Yearrr_AverageAnnualReturnYear0115.51%
Since Inceptionrr_AverageAnnualReturnSinceInception17.58%
Inception Daterr_AverageAnnualReturnInceptionDateDec. 31, 2008
Perkins Mid Cap Value Fund | Class A, C, S, I, R, T Shares
 
Risk/Return:rr_RiskReturnAbstract 
Risk/Return [Heading]rr_RiskReturnHeadingFUND SUMMARY Perkins Mid Cap Value Fund
Objective [Heading]rr_ObjectiveHeadingINVESTMENT OBJECTIVE
Objective, Primary [Text Block]rr_ObjectivePrimaryTextBlockPerkins Mid Cap Value Fund seeks capital appreciation.
FEES AND EXPENSES OF THE FUNDjif277751_FundFeesAndExpensesAbstract 
Expense [Heading]rr_ExpenseHeadingFEES AND EXPENSES OF THE FUND
Expense Narrative [Text Block]rr_ExpenseNarrativeTextBlockThis 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.
Expense Breakpoint Discountsjif277751_ExpenseBreakpointDiscountsAbstract 
Expense Breakpoint Discounts [Text]rr_ExpenseBreakpointDiscountsFor 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 48 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_ExpenseBreakpointMinimumInvestmentRequiredAmount50,000
SHAREHOLDER FEESrr_ShareholderFeesAbstract 
Shareholder Fees Caption [Text]rr_ShareholderFeesCaptionSHAREHOLDER FEES (fees paid directly from your investment)
ANNUAL FUND OPERATING EXPENSESrr_OperatingExpensesAbstract 
Operating Expenses Caption [Text]rr_OperatingExpensesCaptionANNUAL 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 Terminationrr_FeeWaiverOrReimbursementOverAssetsDateOfTerminationNovember 1, 2012
EXAMPLE:rr_ExpenseExampleAbstract 
Expense Example [Heading]rr_ExpenseExampleHeadingEXAMPLE:
Expense Example Narrative [Text Block]rr_ExpenseExampleNarrativeTextBlockThe 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 [Heading]rr_ExpenseExampleByYearHeadingThe 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 by, Year, Caption [Text]rr_ExpenseExampleByYearCaptionIf Shares are redeemed:
Expense Example, No Redemption:rr_ExpenseExampleNoRedemptionAbstract 
Expense Example, No Redemption, By Year, Caption [Text]rr_ExpenseExampleNoRedemptionByYearCaptionIf Shares are not redeemed:
Portfolio Turnover:jif277751_PortfolioTurnoverAltAbstract 
Portfolio Turnover [Heading]rr_PortfolioTurnoverHeadingPortfolio Turnover:
Portfolio Turnover [Text Block]rr_PortfolioTurnoverTextBlockThe 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 period, the Fund’s portfolio turnover rate was 66% of the average value of its portfolio.
Portfolio Turnover, Raterr_PortfolioTurnoverRate66.00%
Principal Investment Strategiesjif277751_PrincipalInvestmentStrategiesAbstract 
Strategy [Heading]rr_StrategyHeadingPRINCIPAL 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, 2011, they ranged from approximately $1.4 billion to $17.8 billion. The Fund may 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 assets in securities of companies having market capitalizations outside of the aforementioned market capitalization ranges or in cash or cash equivalents.

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 also invest its assets in derivatives, which are instruments that have a value derived from an underlying asset, such as equity securities, bonds, commodities, currencies, interest rates, or market indices, as substitutes for securities in which the Fund invests. The Fund has invested in and may continue to invest in derivative instruments (by taking long and/or short positions) including, but not limited to, put and call options, particularly on market indices, for hedging purposes (to offset risks associated with an investment, currency exposure or market conditions). The Fund may invest in other types of derivatives and may do so for other purposes including 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. For more information on the Fund’s use of derivatives, refer to the Fund’s shareholder reports and Form N-Q reports, which are filed with the Securities and Exchange Commission.

Principal Investment Risksjif277751_PrincipalInvestmentRisksAbstract 
Risk [Heading]rr_RiskHeadingPRINCIPAL 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.

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.

Foreign Exposure Risk. The Fund may have exposure to foreign markets, including 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. 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.

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 can be substantially greater than the derivative’s original cost, and can therefore involve 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_RiskLoseMoneyThe biggest risk is that the Fund’s returns will vary, and you could lose money.
Risk Not Insured Depository Institution [Text]rr_RiskNotInsuredDepositoryInstitutionAn 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 INFORMATIONjif277751_FundPastPerformanceAbstract 
Bar Chart and Performance Table [Heading]rr_BarChartAndPerformanceTableHeadingPERFORMANCE 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.

• 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, without the effect of any 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, without the effect of any 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, 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 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.

Bar Chart Does Not Reflect Sales Loads [Text]rr_BarChartDoesNotReflectSalesLoadsThe 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.
Performance Additional Market Index [Text]rr_PerformanceAdditionalMarketIndexThe 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 Past Does Not Indicate Future [Text]rr_PerformancePastDoesNotIndicateFutureThe Fund’s past performance (before and after taxes) does not necessarily indicate how it will perform in the future.
Performance Table Closing [Text Block]rr_PerformanceTableClosingTextBlockUpdated performance information is available at janus.com/advisor/mutual-funds or by calling 1-877-335-2687.
Performance Availability Website Address [Text]rr_PerformanceAvailabilityWebSiteAddressjanus.com/advisor/mutual-funds
Performance Availability Phone [Text]rr_PerformanceAvailabilityPhone1-877-335-2687.
Annual Total Returnsrr_BarChartTableAbstract 
Bar Chart [Heading]rr_BarChartHeadingAnnual Total Returns for Class T Shares (calendar year-end)
Bar Chart Closing [Text Block]rr_BarChartClosingTextBlock

Best Quarter:  Fourth Quarter 2001  21.28%          Worst Quarter:  Fourth Quarter 2008  -19.63%

Year to Date Return, Labelrr_YearToDateReturnLabelThe Fund’s year-to-date return as of the calendar quarter ended September 30, 2011 was -11.70%.
Bar Chart, Year to Date Return, Daterr_BarChartYearToDateReturnDateSep. 30, 2011
Bar Chart, Year to Date Returnrr_BarChartYearToDateReturn(11.70%)
Average Annual Total Returnsrr_AverageAnnualReturnAbstract 
Captionrr_AverageAnnualReturnCaptionAverage Annual Total Returns (periods ended 12/31/10)
Performance Table Narrativerr_PerformanceTableNarrativeTextBlock

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 Uses Highest Federal Raterr_PerformanceTableUsesHighestFederalRateAfter-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 Deferredrr_PerformanceTableNotRelevantToTaxDeferredActual 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_PerformanceTableOneClassOfAfterTaxShownAfter-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.
Perkins Mid Cap Value Fund | Class A, C, S, I, R, T Shares | Class A
 
SHAREHOLDER FEESrr_ShareholderFeesAbstract 
Shareholder Fees Column [Text]rr_ShareholderFeesColumnNameClass A
Maximum Sales Charge (load) Imposed on Purchases (as a percentage of offering price)rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice5.75%
Maximum Deferred Sales Charge (load) (as a percentage of the lower of original purchase price or redemption proceeds)rr_MaximumDeferredSalesChargeOverOther none
ANNUAL FUND OPERATING EXPENSESrr_OperatingExpensesAbstract 
Operating Expenses Column [Text]rr_OperatingExpensesColumnNameClass A
Management Feesrr_ManagementFeesOverAssets0.70%
Distribution/Service (12b-1) Feesrr_DistributionAndService12b1FeesOverAssets0.25%
Other Expensesrr_OtherExpensesOverAssets0.26%
Total Annual Fund Operating Expensesrr_ExpensesOverAssets1.21%[29]
Fee Waiverrr_FeeWaiverOrReimbursementOverAssets0.04%[29]
Net Annual Fund Operating Expenses After Fee Waiverrr_NetExpensesOverAssets1.17%[29]
EXAMPLE:rr_ExpenseExampleAbstract 
Expense Example, By Year, Column [Text]rr_ExpenseExampleByYearColumnNameClass A Shares
1 Yearrr_ExpenseExampleYear01691
3 Yearsrr_ExpenseExampleYear03937
5 Yearsrr_ExpenseExampleYear051,202
10 Yearsrr_ExpenseExampleYear101,957
Expense Example, No Redemption:rr_ExpenseExampleNoRedemptionAbstract 
Expense Example, No Redemption, By Year, Column [Text]rr_ExpenseExampleNoRedemptionByYearColumnNameClass A Shares
1 Yearrr_ExpenseExampleNoRedemptionYear01691
3 Yearsrr_ExpenseExampleNoRedemptionYear03937
5 Yearsrr_ExpenseExampleNoRedemptionYear051,202
10 Yearsrr_ExpenseExampleNoRedemptionYear101,957
Perkins Mid Cap Value Fund | Class A, C, S, I, R, T Shares | Class C
 
SHAREHOLDER FEESrr_ShareholderFeesAbstract 
Shareholder Fees Column [Text]rr_ShareholderFeesColumnNameClass 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_MaximumDeferredSalesChargeOverOther1.00%
ANNUAL FUND OPERATING EXPENSESrr_OperatingExpensesAbstract 
Operating Expenses Column [Text]rr_OperatingExpensesColumnNameClass C
Management Feesrr_ManagementFeesOverAssets0.70%
Distribution/Service (12b-1) Feesrr_DistributionAndService12b1FeesOverAssets1.00%
Other Expensesrr_OtherExpensesOverAssets0.18%
Total Annual Fund Operating Expensesrr_ExpensesOverAssets1.88%[29]
Fee Waiverrr_FeeWaiverOrReimbursementOverAssets none [29]
Net Annual Fund Operating Expenses After Fee Waiverrr_NetExpensesOverAssets1.88%[29]
EXAMPLE:rr_ExpenseExampleAbstract 
Expense Example, By Year, Column [Text]rr_ExpenseExampleByYearColumnNameClass C Shares
1 Yearrr_ExpenseExampleYear01291
3 Yearsrr_ExpenseExampleYear03591
5 Yearsrr_ExpenseExampleYear051,016
10 Yearsrr_ExpenseExampleYear102,201
Expense Example, No Redemption:rr_ExpenseExampleNoRedemptionAbstract 
Expense Example, No Redemption, By Year, Column [Text]rr_ExpenseExampleNoRedemptionByYearColumnNameClass C Shares
1 Yearrr_ExpenseExampleNoRedemptionYear01191
3 Yearsrr_ExpenseExampleNoRedemptionYear03591
5 Yearsrr_ExpenseExampleNoRedemptionYear051,016
10 Yearsrr_ExpenseExampleNoRedemptionYear102,201
Perkins Mid Cap Value Fund | Class A, C, S, I, R, T Shares | Class S
 
SHAREHOLDER FEESrr_ShareholderFeesAbstract 
Shareholder Fees Column [Text]rr_ShareholderFeesColumnNameClass 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
ANNUAL FUND OPERATING EXPENSESrr_OperatingExpensesAbstract 
Operating Expenses Column [Text]rr_OperatingExpensesColumnNameClass S
Management Feesrr_ManagementFeesOverAssets0.70%
Distribution/Service (12b-1) Feesrr_DistributionAndService12b1FeesOverAssets0.25%
Other Expensesrr_OtherExpensesOverAssets0.30%
Total Annual Fund Operating Expensesrr_ExpensesOverAssets1.25%[29]
Fee Waiverrr_FeeWaiverOrReimbursementOverAssets none [29]
Net Annual Fund Operating Expenses After Fee Waiverrr_NetExpensesOverAssets1.25%[29]
EXAMPLE:rr_ExpenseExampleAbstract 
Expense Example, By Year, Column [Text]rr_ExpenseExampleByYearColumnNameClass S Shares
1 Yearrr_ExpenseExampleYear01127
3 Yearsrr_ExpenseExampleYear03397
5 Yearsrr_ExpenseExampleYear05686
10 Yearsrr_ExpenseExampleYear101,511
Expense Example, No Redemption:rr_ExpenseExampleNoRedemptionAbstract 
Expense Example, No Redemption, By Year, Column [Text]rr_ExpenseExampleNoRedemptionByYearColumnNameClass S Shares
1 Yearrr_ExpenseExampleNoRedemptionYear01127
3 Yearsrr_ExpenseExampleNoRedemptionYear03397
5 Yearsrr_ExpenseExampleNoRedemptionYear05686
10 Yearsrr_ExpenseExampleNoRedemptionYear101,511
Perkins Mid Cap Value Fund | Class A, C, S, I, R, T Shares | Class I
 
SHAREHOLDER FEESrr_ShareholderFeesAbstract 
Shareholder Fees Column [Text]rr_ShareholderFeesColumnNameClass 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
ANNUAL FUND OPERATING EXPENSESrr_OperatingExpensesAbstract 
Operating Expenses Column [Text]rr_OperatingExpensesColumnNameClass I
Management Feesrr_ManagementFeesOverAssets0.70%
Distribution/Service (12b-1) Feesrr_DistributionAndService12b1FeesOverAssets none
Other Expensesrr_OtherExpensesOverAssets0.15%
Total Annual Fund Operating Expensesrr_ExpensesOverAssets0.85%[29]
Fee Waiverrr_FeeWaiverOrReimbursementOverAssets none [29]
Net Annual Fund Operating Expenses After Fee Waiverrr_NetExpensesOverAssets0.85%[29]
EXAMPLE:rr_ExpenseExampleAbstract 
Expense Example, By Year, Column [Text]rr_ExpenseExampleByYearColumnNameClass I Shares
1 Yearrr_ExpenseExampleYear0187
3 Yearsrr_ExpenseExampleYear03271
5 Yearsrr_ExpenseExampleYear05471
10 Yearsrr_ExpenseExampleYear101,049
Expense Example, No Redemption:rr_ExpenseExampleNoRedemptionAbstract 
Expense Example, No Redemption, By Year, Column [Text]rr_ExpenseExampleNoRedemptionByYearColumnNameClass I Shares
1 Yearrr_ExpenseExampleNoRedemptionYear0187
3 Yearsrr_ExpenseExampleNoRedemptionYear03271
5 Yearsrr_ExpenseExampleNoRedemptionYear05471
10 Yearsrr_ExpenseExampleNoRedemptionYear101,049
Perkins Mid Cap Value Fund | Class A, C, S, I, R, T Shares | Class R
 
SHAREHOLDER FEESrr_ShareholderFeesAbstract 
Shareholder Fees Column [Text]rr_ShareholderFeesColumnNameClass 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
ANNUAL FUND OPERATING EXPENSESrr_OperatingExpensesAbstract 
Operating Expenses Column [Text]rr_OperatingExpensesColumnNameClass R
Management Feesrr_ManagementFeesOverAssets0.70%
Distribution/Service (12b-1) Feesrr_DistributionAndService12b1FeesOverAssets0.50%
Other Expensesrr_OtherExpensesOverAssets0.30%
Total Annual Fund Operating Expensesrr_ExpensesOverAssets1.50%[29]
Fee Waiverrr_FeeWaiverOrReimbursementOverAssets none [29]
Net Annual Fund Operating Expenses After Fee Waiverrr_NetExpensesOverAssets1.50%[29]
EXAMPLE:rr_ExpenseExampleAbstract 
Expense Example, By Year, Column [Text]rr_ExpenseExampleByYearColumnNameClass R Shares
1 Yearrr_ExpenseExampleYear01153
3 Yearsrr_ExpenseExampleYear03474
5 Yearsrr_ExpenseExampleYear05818
10 Yearsrr_ExpenseExampleYear101,791
Expense Example, No Redemption:rr_ExpenseExampleNoRedemptionAbstract 
Expense Example, No Redemption, By Year, Column [Text]rr_ExpenseExampleNoRedemptionByYearColumnNameClass R Shares
1 Yearrr_ExpenseExampleNoRedemptionYear01153
3 Yearsrr_ExpenseExampleNoRedemptionYear03474
5 Yearsrr_ExpenseExampleNoRedemptionYear05818
10 Yearsrr_ExpenseExampleNoRedemptionYear101,791
Perkins Mid Cap Value Fund | Class A, C, S, I, R, T Shares | Class T
 
SHAREHOLDER FEESrr_ShareholderFeesAbstract 
Shareholder Fees Column [Text]rr_ShareholderFeesColumnNameClass 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
ANNUAL FUND OPERATING EXPENSESrr_OperatingExpensesAbstract 
Operating Expenses Column [Text]rr_OperatingExpensesColumnNameClass T
Management Feesrr_ManagementFeesOverAssets0.70%
Distribution/Service (12b-1) Feesrr_DistributionAndService12b1FeesOverAssets none
Other Expensesrr_OtherExpensesOverAssets0.30%
Total Annual Fund Operating Expensesrr_ExpensesOverAssets1.00%[29]
Fee Waiverrr_FeeWaiverOrReimbursementOverAssets none [29]
Net Annual Fund Operating Expenses After Fee Waiverrr_NetExpensesOverAssets1.00%[29]
EXAMPLE:rr_ExpenseExampleAbstract 
Expense Example, By Year, Column [Text]rr_ExpenseExampleByYearColumnNameClass T Shares
1 Yearrr_ExpenseExampleYear01102
3 Yearsrr_ExpenseExampleYear03318
5 Yearsrr_ExpenseExampleYear05552
10 Yearsrr_ExpenseExampleYear101,225
Expense Example, No Redemption:rr_ExpenseExampleNoRedemptionAbstract 
Expense Example, No Redemption, By Year, Column [Text]rr_ExpenseExampleNoRedemptionByYearColumnNameClass T Shares
1 Yearrr_ExpenseExampleNoRedemptionYear01102
3 Yearsrr_ExpenseExampleNoRedemptionYear03318
5 Yearsrr_ExpenseExampleNoRedemptionYear05552
10 Yearsrr_ExpenseExampleNoRedemptionYear101,225
Annual Total Returnsrr_BarChartTableAbstract 
2001rr_AnnualReturn200120.52%
2002rr_AnnualReturn2002(13.09%)
2003rr_AnnualReturn200339.33%
2004rr_AnnualReturn200418.36%
2005rr_AnnualReturn200510.36%
2006rr_AnnualReturn200615.25%
2007rr_AnnualReturn20077.43%
2008rr_AnnualReturn2008(27.33%)
2009rr_AnnualReturn200930.37%
2010rr_AnnualReturn201014.81%
Highest Quarterly Return, Labelrr_HighestQuarterlyReturnLabelBest Quarter:
Highest Quarterly Return, Daterr_BarChartHighestQuarterlyReturnDateDec. 31, 2001
Highest Quarterly Returnrr_BarChartHighestQuarterlyReturn21.28%
Lowest Quarterly Return, Labelrr_LowestQuarterlyReturnLabelWorst Quarter:
Lowest Quarterly Return, Daterr_BarChartLowestQuarterlyReturnDateDec. 31, 2008
Lowest Quarterly Returnrr_BarChartLowestQuarterlyReturn(19.63%)
Perkins Mid Cap Value Fund | Class A, C, S, I, R, T Shares | Return Before Taxes | Class A
 
Average Annual Total Returnsrr_AverageAnnualReturnAbstract 
Columnrr_AverageAnnualReturnColumnNameClass A Shares
Labelrr_AverageAnnualReturnLabelReturn Before Taxes[3]
1 Yearrr_AverageAnnualReturnYear018.05%
5 Yearsrr_AverageAnnualReturnYear054.68%
10 Yearsrr_AverageAnnualReturnYear109.06%
Since Inceptionrr_AverageAnnualReturnSinceInception12.32%
Inception Daterr_AverageAnnualReturnInceptionDateAug. 12, 1998
Perkins Mid Cap Value Fund | Class A, C, S, I, R, T Shares | Return Before Taxes | Class C
 
Average Annual Total Returnsrr_AverageAnnualReturnAbstract 
Columnrr_AverageAnnualReturnColumnNameClass C Shares
Labelrr_AverageAnnualReturnLabelReturn Before Taxes[4]
1 Yearrr_AverageAnnualReturnYear0112.66%
5 Yearsrr_AverageAnnualReturnYear055.16%
10 Yearsrr_AverageAnnualReturnYear108.93%
Since Inceptionrr_AverageAnnualReturnSinceInception12.15%
Inception Daterr_AverageAnnualReturnInceptionDateAug. 12, 1998
Perkins Mid Cap Value Fund | Class A, C, S, I, R, T Shares | Return Before Taxes | Class S
 
Average Annual Total Returnsrr_AverageAnnualReturnAbstract 
Columnrr_AverageAnnualReturnColumnNameClass S Shares
Labelrr_AverageAnnualReturnLabelReturn Before Taxes
1 Yearrr_AverageAnnualReturnYear0114.52%
5 Yearsrr_AverageAnnualReturnYear055.80%
10 Yearsrr_AverageAnnualReturnYear109.58%
Since Inceptionrr_AverageAnnualReturnSinceInception12.75%
Inception Daterr_AverageAnnualReturnInceptionDateAug. 12, 1998
Perkins Mid Cap Value Fund | Class A, C, S, I, R, T Shares | Return Before Taxes | Class I
 
Average Annual Total Returnsrr_AverageAnnualReturnAbstract 
Columnrr_AverageAnnualReturnColumnNameClass I Shares
Labelrr_AverageAnnualReturnLabelReturn Before Taxes
1 Yearrr_AverageAnnualReturnYear0115.02%
5 Yearsrr_AverageAnnualReturnYear056.13%
10 Yearsrr_AverageAnnualReturnYear109.89%
Since Inceptionrr_AverageAnnualReturnSinceInception13.00%
Inception Daterr_AverageAnnualReturnInceptionDateAug. 12, 1998
Perkins Mid Cap Value Fund | Class A, C, S, I, R, T Shares | Return Before Taxes | Class R
 
Average Annual Total Returnsrr_AverageAnnualReturnAbstract 
Columnrr_AverageAnnualReturnColumnNameClass R Shares
Labelrr_AverageAnnualReturnLabelReturn Before Taxes
1 Yearrr_AverageAnnualReturnYear0114.24%
5 Yearsrr_AverageAnnualReturnYear055.54%
10 Yearsrr_AverageAnnualReturnYear109.31%
Since Inceptionrr_AverageAnnualReturnSinceInception12.53%
Inception Daterr_AverageAnnualReturnInceptionDateAug. 12, 1998
Perkins Mid Cap Value Fund | Class A, C, S, I, R, T Shares | Return Before Taxes | Class T
 
Average Annual Total Returnsrr_AverageAnnualReturnAbstract 
Columnrr_AverageAnnualReturnColumnNameClass T Shares
Labelrr_AverageAnnualReturnLabelReturn Before Taxes
1 Yearrr_AverageAnnualReturnYear0114.81%
5 Yearsrr_AverageAnnualReturnYear056.13%
10 Yearsrr_AverageAnnualReturnYear109.89%
Since Inceptionrr_AverageAnnualReturnSinceInception13.00%
Inception Daterr_AverageAnnualReturnInceptionDateAug. 12, 1998
Perkins Mid Cap Value Fund | Class A, C, S, I, R, T Shares | Return After Taxes on Distributions | Class T
 
Average Annual Total Returnsrr_AverageAnnualReturnAbstract 
Columnrr_AverageAnnualReturnColumnNameClass T Shares
Labelrr_AverageAnnualReturnLabelReturn After Taxes on Distributions
1 Yearrr_AverageAnnualReturnYear0114.67%
5 Yearsrr_AverageAnnualReturnYear055.08%
10 Yearsrr_AverageAnnualReturnYear108.84%
Since Inceptionrr_AverageAnnualReturnSinceInception11.54%
Inception Daterr_AverageAnnualReturnInceptionDateAug. 12, 1998
Perkins Mid Cap Value Fund | Class A, C, S, I, R, T Shares | Return After Taxes on Distributions and Sale of Fund Shares | Class T
 
Average Annual Total Returnsrr_AverageAnnualReturnAbstract 
Columnrr_AverageAnnualReturnColumnNameClass T Shares
Labelrr_AverageAnnualReturnLabelReturn After Taxes on Distributions and Sale of Fund Shares[5]
1 Yearrr_AverageAnnualReturnYear019.77%
5 Yearsrr_AverageAnnualReturnYear055.00%
10 Yearsrr_AverageAnnualReturnYear108.40%
Since Inceptionrr_AverageAnnualReturnSinceInception11.01%
Inception Daterr_AverageAnnualReturnInceptionDateAug. 12, 1998
Perkins Mid Cap Value Fund | Class A, C, S, I, R, T Shares | Russell Midcap® Value Index
 
Average Annual Total Returnsrr_AverageAnnualReturnAbstract 
Labelrr_AverageAnnualReturnLabelRussell Midcap® Value Index
Index No Deduction for Fees, Expenses, Taxes [Text]rr_IndexNoDeductionForFeesExpensesTaxes(reflects no deduction for expenses, fees, or taxes)
1 Yearrr_AverageAnnualReturnYear0124.75%
5 Yearsrr_AverageAnnualReturnYear054.08%
10 Yearsrr_AverageAnnualReturnYear108.07%
Since Inceptionrr_AverageAnnualReturnSinceInception8.47%
Inception Daterr_AverageAnnualReturnInceptionDateAug. 12, 1998
Perkins Mid Cap Value Fund | Class D Shares
 
Risk/Return:rr_RiskReturnAbstract 
Risk/Return [Heading]rr_RiskReturnHeadingFUND SUMMARY Perkins Mid Cap Value Fund
Objective [Heading]rr_ObjectiveHeadingINVESTMENT OBJECTIVE
Objective, Primary [Text Block]rr_ObjectivePrimaryTextBlockPerkins Mid Cap Value Fund seeks capital appreciation.
FEES AND EXPENSES OF THE FUNDjif277751_FundFeesAndExpensesAbstract 
Expense [Heading]rr_ExpenseHeadingFEES AND EXPENSES OF THE FUND
Expense Narrative [Text Block]rr_ExpenseNarrativeTextBlockThis table describes the fees and expenses that you may pay if you buy and hold Shares of the Fund.
ANNUAL FUND OPERATING EXPENSESrr_OperatingExpensesAbstract 
Operating Expenses Caption [Text]rr_OperatingExpensesCaptionANNUAL 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 Terminationrr_FeeWaiverOrReimbursementOverAssetsDateOfTerminationNovember 1, 2012
EXAMPLE:rr_ExpenseExampleAbstract 
Expense Example [Heading]rr_ExpenseExampleHeadingEXAMPLE:
Expense Example Narrative [Text Block]rr_ExpenseExampleNarrativeTextBlockThe 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 [Heading]rr_ExpenseExampleByYearHeadingThe 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:
Portfolio Turnover:jif277751_PortfolioTurnoverAltAbstract 
Portfolio Turnover [Heading]rr_PortfolioTurnoverHeadingPortfolio Turnover:
Portfolio Turnover [Text Block]rr_PortfolioTurnoverTextBlockThe 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 period, the Fund’s portfolio turnover rate was 66% of the average value of its portfolio.
Portfolio Turnover, Raterr_PortfolioTurnoverRate66.00%
Principal Investment Strategiesjif277751_PrincipalInvestmentStrategiesAbstract 
Strategy [Heading]rr_StrategyHeadingPRINCIPAL 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, 2011, they ranged from approximately $1.4 billion to $17.8 billion. The Fund may 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 assets in securities of companies having market capitalizations outside of the aforementioned market capitalization ranges or in cash or cash equivalents.

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 also invest its assets in derivatives, which are instruments that have a value derived from an underlying asset, such as equity securities, bonds, commodities, currencies, interest rates, or market indices, as substitutes for securities in which the Fund invests. The Fund has invested in and may continue to invest in derivative instruments (by taking long and/or short positions) including, but not limited to, put and call options, particularly on market indices, for hedging purposes (to offset risks associated with an investment, currency exposure or market conditions). The Fund may invest in other types of derivatives and may do so for other purposes including 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. For more information on the Fund’s use of derivatives, refer to the Fund’s shareholder reports and Form N-Q reports, which are filed with the Securities and Exchange Commission.

Principal Investment Risksjif277751_PrincipalInvestmentRisksAbstract 
Risk [Heading]rr_RiskHeadingPRINCIPAL 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.

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.

Foreign Exposure Risk. The Fund may have exposure to foreign markets, including 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. 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.

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 can be substantially greater than the derivative’s original cost, and can therefore involve 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_RiskLoseMoneyThe biggest risk is that the Fund’s returns will vary, and you could lose money.
Risk Not Insured Depository Institution [Text]rr_RiskNotInsuredDepositoryInstitutionAn 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 INFORMATIONjif277751_FundPastPerformanceAbstract 
Bar Chart and Performance Table [Heading]rr_BarChartAndPerformanceTableHeadingPERFORMANCE 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 December 31, 2009, 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 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_PerformanceAdditionalMarketIndexThe 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 Past Does Not Indicate Future [Text]rr_PerformancePastDoesNotIndicateFutureThe Fund’s past performance (before and after taxes) does not necessarily indicate how it will perform in the future.
Performance Table Closing [Text Block]rr_PerformanceTableClosingTextBlockUpdated performance information is available at janus.com/allfunds or by calling 1-800-525-3713.
Performance Availability Website Address [Text]rr_PerformanceAvailabilityWebSiteAddressjanus.com/allfunds
Performance Availability Phone [Text]rr_PerformanceAvailabilityPhone1-800-525-3713
Annual Total Returnsrr_BarChartTableAbstract 
Bar Chart [Heading]rr_BarChartHeadingAnnual Total Returns for Class D Shares (calendar year-end)
Bar Chart Closing [Text Block]rr_BarChartClosingTextBlock

Best Quarter: Fourth Quarter 2001 21.28%          Worst Quarter: Fourth Quarter 2008 -19.63%

Year to Date Return, Labelrr_YearToDateReturnLabelThe Fund’s year-to-date return as of the calendar quarter ended September 30, 2011 was -11.61%.
Bar Chart, Year to Date Return, Daterr_BarChartYearToDateReturnDateSep. 30, 2011
Bar Chart, Year to Date Returnrr_BarChartYearToDateReturn(11.61%)
Average Annual Total Returnsrr_AverageAnnualReturnAbstract 
Captionrr_AverageAnnualReturnCaptionAverage Annual Total Returns (periods ended 12/31/10)
Performance Table Narrativerr_PerformanceTableNarrativeTextBlockAfter-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 Uses Highest Federal Raterr_PerformanceTableUsesHighestFederalRateAfter-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 Deferredrr_PerformanceTableNotRelevantToTaxDeferredActual 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.
Perkins Mid Cap Value Fund | Class D Shares | Class D
 
ANNUAL FUND OPERATING EXPENSESrr_OperatingExpensesAbstract 
Operating Expenses Column [Text]rr_OperatingExpensesColumnNameClass D
Management Feesrr_ManagementFeesOverAssets0.70%
Other Expensesrr_OtherExpensesOverAssets0.19%
Total Annual Fund Operating Expensesrr_ExpensesOverAssets0.89%[30]
EXAMPLE:rr_ExpenseExampleAbstract 
Expense Example, By Year, Column [Text]rr_ExpenseExampleByYearColumnNameClass D Shares
1 Yearrr_ExpenseExampleYear0191
3 Yearsrr_ExpenseExampleYear03284
5 Yearsrr_ExpenseExampleYear05493
10 Yearsrr_ExpenseExampleYear101,096
Annual Total Returnsrr_BarChartTableAbstract 
2001rr_AnnualReturn200120.52%
2002rr_AnnualReturn2002(13.09%)
2003rr_AnnualReturn200339.33%
2004rr_AnnualReturn200418.36%
2005rr_AnnualReturn200510.36%
2006rr_AnnualReturn200615.25%
2007rr_AnnualReturn20077.43%
2008rr_AnnualReturn2008(27.33%)
2009rr_AnnualReturn200930.37%
2010rr_AnnualReturn201014.91%
Highest Quarterly Return, Labelrr_HighestQuarterlyReturnLabelBest Quarter:
Highest Quarterly Return, Daterr_BarChartHighestQuarterlyReturnDateDec. 31, 2001
Highest Quarterly Returnrr_BarChartHighestQuarterlyReturn21.28%
Lowest Quarterly Return, Labelrr_LowestQuarterlyReturnLabelWorst Quarter:
Lowest Quarterly Return, Daterr_BarChartLowestQuarterlyReturnDateDec. 31, 2008
Lowest Quarterly Returnrr_BarChartLowestQuarterlyReturn(19.63%)
Perkins Mid Cap Value Fund | Class D Shares | Return Before Taxes | Class D
 
Average Annual Total Returnsrr_AverageAnnualReturnAbstract 
Columnrr_AverageAnnualReturnColumnNameClass D Shares
Labelrr_AverageAnnualReturnLabelReturn Before Taxes
1 Yearrr_AverageAnnualReturnYear0114.91%
5 Yearsrr_AverageAnnualReturnYear056.15%
10 Yearsrr_AverageAnnualReturnYear109.90%
Since Inceptionrr_AverageAnnualReturnSinceInception13.01%
Inception Daterr_AverageAnnualReturnInceptionDateAug. 12, 1998
Perkins Mid Cap Value Fund | Class D Shares | Return After Taxes on Distributions | Class D
 
Average Annual Total Returnsrr_AverageAnnualReturnAbstract 
Columnrr_AverageAnnualReturnColumnNameClass D Shares
Labelrr_AverageAnnualReturnLabelReturn After Taxes on Distributions
1 Yearrr_AverageAnnualReturnYear0114.75%
5 Yearsrr_AverageAnnualReturnYear055.10%
10 Yearsrr_AverageAnnualReturnYear108.85%
Since Inceptionrr_AverageAnnualReturnSinceInception11.55%
Inception Daterr_AverageAnnualReturnInceptionDateAug. 12, 1998
Perkins Mid Cap Value Fund | Class D Shares | Return After Taxes on Distributions and Sale of Fund Shares | Class D
 
Average Annual Total Returnsrr_AverageAnnualReturnAbstract 
Columnrr_AverageAnnualReturnColumnNameClass D Shares
Labelrr_AverageAnnualReturnLabelReturn After Taxes on Distributions and Sale of Fund Shares[5]
1 Yearrr_AverageAnnualReturnYear019.85%
5 Yearsrr_AverageAnnualReturnYear055.01%
10 Yearsrr_AverageAnnualReturnYear108.41%
Since Inceptionrr_AverageAnnualReturnSinceInception11.01%
Inception Daterr_AverageAnnualReturnInceptionDateAug. 12, 1998
Perkins Mid Cap Value Fund | Class D Shares | Russell Midcap® Value Index
 
Average Annual Total Returnsrr_AverageAnnualReturnAbstract 
Labelrr_AverageAnnualReturnLabelRussell Midcap® Value Index
Index No Deduction for Fees, Expenses, Taxes [Text]rr_IndexNoDeductionForFeesExpensesTaxes(reflects no deduction for expenses, fees, or taxes)
1 Yearrr_AverageAnnualReturnYear0124.75%
5 Yearsrr_AverageAnnualReturnYear054.08%
10 Yearsrr_AverageAnnualReturnYear108.07%
Since Inceptionrr_AverageAnnualReturnSinceInception8.47%
Inception Daterr_AverageAnnualReturnInceptionDateAug. 12, 1998
Perkins Mid Cap Value Fund | Class L Shares
 
Risk/Return:rr_RiskReturnAbstract 
Risk/Return [Heading]rr_RiskReturnHeadingFUND SUMMARY Perkins Mid Cap Value Fund
Objective [Heading]rr_ObjectiveHeadingINVESTMENT OBJECTIVE
Objective, Primary [Text Block]rr_ObjectivePrimaryTextBlockPerkins Mid Cap Value Fund seeks capital appreciation.
FEES AND EXPENSES OF THE FUNDjif277751_FundFeesAndExpensesAbstract 
Expense [Heading]rr_ExpenseHeadingFEES AND EXPENSES OF THE FUND
Expense Narrative [Text Block]rr_ExpenseNarrativeTextBlockThis table describes the fees and expenses that you may pay if you buy and hold Shares of the Fund.
ANNUAL FUND OPERATING EXPENSESrr_OperatingExpensesAbstract 
Operating Expenses Caption [Text]rr_OperatingExpensesCaptionANNUAL 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 Terminationrr_FeeWaiverOrReimbursementOverAssetsDateOfTerminationNovember 1, 2012
EXAMPLE:rr_ExpenseExampleAbstract 
Expense Example [Heading]rr_ExpenseExampleHeadingEXAMPLE:
Expense Example Narrative [Text Block]rr_ExpenseExampleNarrativeTextBlockThe 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 [Heading]rr_ExpenseExampleByYearHeadingThe 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:
Portfolio Turnover:jif277751_PortfolioTurnoverAltAbstract 
Portfolio Turnover [Heading]rr_PortfolioTurnoverHeadingPortfolio Turnover:
Portfolio Turnover [Text Block]rr_PortfolioTurnoverTextBlockThe 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 period, the Fund’s portfolio turnover rate was 66% of the average value of its portfolio.
Portfolio Turnover, Raterr_PortfolioTurnoverRate66.00%
Principal Investment Strategiesjif277751_PrincipalInvestmentStrategiesAbstract 
Strategy [Heading]rr_StrategyHeadingPRINCIPAL 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, 2011, they ranged from approximately $1.4 billion to $17.8 billion. The Fund may 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 assets in securities of companies having market capitalizations outside of the aforementioned market capitalization ranges or in cash or cash equivalents.

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 also invest its assets in derivatives, which are instruments that have a value derived from an underlying asset, such as equity securities, bonds, commodities, currencies, interest rates, or market indices, as substitutes for securities in which the Fund invests. The Fund has invested in and may continue to invest in derivative instruments (by taking long and/or short positions) including, but not limited to, put and call options, particularly on market indices, for hedging purposes (to offset risks associated with an investment, currency exposure or market conditions). The Fund may invest in other types of derivatives and may do so for other purposes including 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. For more information on the Fund’s use of derivatives, refer to the Fund’s shareholder reports and Form N-Q reports, which are filed with the Securities and Exchange Commission.

Principal Investment Risksjif277751_PrincipalInvestmentRisksAbstract 
Risk [Heading]rr_RiskHeadingPRINCIPAL 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.

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.

Foreign Exposure Risk. The Fund may have exposure to foreign markets, including 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. 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.

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 can be substantially greater than the derivative’s original cost, and can therefore involve 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_RiskLoseMoneyThe biggest risk is that the Fund’s returns will vary, and you could lose money.
Risk Not Insured Depository Institution [Text]rr_RiskNotInsuredDepositoryInstitutionAn 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 INFORMATIONjif277751_FundPastPerformanceAbstract 
Bar Chart and Performance Table [Heading]rr_BarChartAndPerformanceTableHeadingPERFORMANCE 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_PerformanceAdditionalMarketIndexThe 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 Past Does Not Indicate Future [Text]rr_PerformancePastDoesNotIndicateFutureThe Fund’s past performance (before and after taxes) does not necessarily indicate how it will perform in the future.
Performance Table Closing [Text Block]rr_PerformanceTableClosingTextBlockUpdated performance information is available at janus.com/advisor/mutual-funds or by calling 1-877-335-2687.
Performance Availability Website Address [Text]rr_PerformanceAvailabilityWebSiteAddress janus.com/advisor/mutual-funds
Performance Availability Phone [Text]rr_PerformanceAvailabilityPhone1-877-335-2687
Annual Total Returnsrr_BarChartTableAbstract 
Bar Chart [Heading]rr_BarChartHeadingAnnual Total Returns for Class L Shares (calendar year-end)[31]
Bar Chart Closing [Text Block]rr_BarChartClosingTextBlock

Best Quarter:  Fourth Quarter 2001  21.28%           Worst Quarter:  Fourth Quarter 2008  -19.63%

Year to Date Return, Labelrr_YearToDateReturnLabelThe Fund’s year-to-date return as of the calendar quarter ended September 30, 2011 was -11.49%.
Bar Chart, Year to Date Return, Daterr_BarChartYearToDateReturnDateSep. 30, 2011
Bar Chart, Year to Date Returnrr_BarChartYearToDateReturn(11.49%)
Average Annual Total Returnsrr_AverageAnnualReturnAbstract 
Captionrr_AverageAnnualReturnCaptionAverage Annual Total Returns (periods ended 12/31/10)[31]
Performance Table Narrativerr_PerformanceTableNarrativeTextBlockAfter-tax returns are calculated using distributions for the Fund’s Class L Shares (formerly named Institutional Shares) for the period April 21, 2003 to December 31, 2009; 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 Uses Highest Federal Raterr_PerformanceTableUsesHighestFederalRateAfter-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 Deferredrr_PerformanceTableNotRelevantToTaxDeferredActual 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.
Perkins Mid Cap Value Fund | Class L Shares | Class L
 
ANNUAL FUND OPERATING EXPENSESrr_OperatingExpensesAbstract 
Operating Expenses Column [Text]rr_OperatingExpensesColumnNameClass L
Management Feesrr_ManagementFeesOverAssets0.70%
Other Expensesrr_OtherExpensesOverAssets0.30%
Total Annual Fund Operating Expensesrr_ExpensesOverAssets1.00%[30]
EXAMPLE:rr_ExpenseExampleAbstract 
Expense Example, By Year, Column [Text]rr_ExpenseExampleByYearColumnNameClass L Shares
1 Yearrr_ExpenseExampleYear01102
3 Yearsrr_ExpenseExampleYear03318
5 Yearsrr_ExpenseExampleYear05552
10 Yearsrr_ExpenseExampleYear101,225
Annual Total Returnsrr_BarChartTableAbstract 
2001rr_AnnualReturn200120.52%[31]
2002rr_AnnualReturn2002(12.95%)[31]
2003rr_AnnualReturn200339.77%
2004rr_AnnualReturn200418.56%
2005rr_AnnualReturn200510.53%
2006rr_AnnualReturn200615.42%
2007rr_AnnualReturn20077.56%
2008rr_AnnualReturn2008(27.19%)
2009rr_AnnualReturn200930.74%
2010rr_AnnualReturn201015.01%
Highest Quarterly Return, Labelrr_HighestQuarterlyReturnLabelBest Quarter:
Highest Quarterly Return, Daterr_BarChartHighestQuarterlyReturnDateDec. 31, 2001
Highest Quarterly Returnrr_BarChartHighestQuarterlyReturn21.28%
Lowest Quarterly Return, Labelrr_LowestQuarterlyReturnLabelWorst Quarter:
Lowest Quarterly Return, Daterr_BarChartLowestQuarterlyReturnDateDec. 31, 2008
Lowest Quarterly Returnrr_BarChartLowestQuarterlyReturn(19.63%)
Perkins Mid Cap Value Fund | Class L Shares | Return Before Taxes | Class L
 
Average Annual Total Returnsrr_AverageAnnualReturnAbstract 
Columnrr_AverageAnnualReturnColumnNameClass L Shares
Labelrr_AverageAnnualReturnLabelReturn Before Taxes
1 Yearrr_AverageAnnualReturnYear0115.01%
5 Yearsrr_AverageAnnualReturnYear056.33%
10 Yearsrr_AverageAnnualReturnYear1010.08%
Since Inceptionrr_AverageAnnualReturnSinceInception13.16%
Inception Daterr_AverageAnnualReturnInceptionDateAug. 12, 1998
Perkins Mid Cap Value Fund | Class L Shares | Return After Taxes on Distributions | Class L
 
Average Annual Total Returnsrr_AverageAnnualReturnAbstract 
Columnrr_AverageAnnualReturnColumnNameClass L Shares
Labelrr_AverageAnnualReturnLabelReturn After Taxes on Distributions
1 Yearrr_AverageAnnualReturnYear0114.85%
5 Yearsrr_AverageAnnualReturnYear055.26%
10 Yearsrr_AverageAnnualReturnYear109.00%
Since Inceptionrr_AverageAnnualReturnSinceInception11.68%
Inception Daterr_AverageAnnualReturnInceptionDateAug. 12, 1998
Perkins Mid Cap Value Fund | Class L Shares | Return After Taxes on Distributions and Sale of Fund Shares | Class L
 
Average Annual Total Returnsrr_AverageAnnualReturnAbstract 
Columnrr_AverageAnnualReturnColumnNameClass L Shares
Labelrr_AverageAnnualReturnLabelReturn After Taxes on Distributions and Sale of Fund Shares[5]
1 Yearrr_AverageAnnualReturnYear019.92%
5 Yearsrr_AverageAnnualReturnYear055.16%
10 Yearsrr_AverageAnnualReturnYear108.56%
Since Inceptionrr_AverageAnnualReturnSinceInception11.14%
Inception Daterr_AverageAnnualReturnInceptionDateAug. 12, 1998
Perkins Mid Cap Value Fund | Class L Shares | Russell Midcap® Value Index
 
Average Annual Total Returnsrr_AverageAnnualReturnAbstract 
Labelrr_AverageAnnualReturnLabelRussell Midcap® Value Index
Index No Deduction for Fees, Expenses, Taxes [Text]rr_IndexNoDeductionForFeesExpensesTaxes(reflects no deduction for expenses, fees, or taxes)
1 Yearrr_AverageAnnualReturnYear0124.75%
5 Yearsrr_AverageAnnualReturnYear054.08%
10 Yearsrr_AverageAnnualReturnYear108.07%
Since Inceptionrr_AverageAnnualReturnSinceInception8.47%
Inception Daterr_AverageAnnualReturnInceptionDateAug. 12, 1998
Perkins Small Cap Value Fund | Class A, C, S, I, R, T Shares
 
Risk/Return:rr_RiskReturnAbstract 
Risk/Return [Heading]rr_RiskReturnHeadingFUND SUMMARY Perkins Small Cap Value Fund
Objective [Heading]rr_ObjectiveHeadingINVESTMENT OBJECTIVE
Objective, Primary [Text Block]rr_ObjectivePrimaryTextBlockPerkins Small Cap Value Fund seeks capital appreciation.
FEES AND EXPENSES OF THE FUNDjif277751_FundFeesAndExpensesAbstract 
Expense [Heading]rr_ExpenseHeadingFEES AND EXPENSES OF THE FUND
Expense Narrative [Text Block]rr_ExpenseNarrativeTextBlockThis 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.
Expense Breakpoint Discountsjif277751_ExpenseBreakpointDiscountsAbstract 
Expense Breakpoint Discounts [Text]rr_ExpenseBreakpointDiscountsFor 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 48 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_ExpenseBreakpointMinimumInvestmentRequiredAmount50,000
SHAREHOLDER FEESrr_ShareholderFeesAbstract 
Shareholder Fees Caption [Text]rr_ShareholderFeesCaptionSHAREHOLDER FEES (fees paid directly from your investment)
ANNUAL FUND OPERATING EXPENSESrr_OperatingExpensesAbstract 
Operating Expenses Caption [Text]rr_OperatingExpensesCaptionANNUAL 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 Terminationrr_FeeWaiverOrReimbursementOverAssetsDateOfTerminationNovember 1, 2012
EXAMPLE:rr_ExpenseExampleAbstract 
Expense Example [Heading]rr_ExpenseExampleHeadingEXAMPLE:
Expense Example Narrative [Text Block]rr_ExpenseExampleNarrativeTextBlockThe 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 [Heading]rr_ExpenseExampleByYearHeadingThe 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 by, Year, Caption [Text]rr_ExpenseExampleByYearCaptionIf Shares are redeemed:
Expense Example, No Redemption:rr_ExpenseExampleNoRedemptionAbstract 
Expense Example, No Redemption, By Year, Caption [Text]rr_ExpenseExampleNoRedemptionByYearCaptionIf Shares are not redeemed:
Portfolio Turnover:jif277751_PortfolioTurnoverAltAbstract 
Portfolio Turnover [Heading]rr_PortfolioTurnoverHeadingPortfolio Turnover:
Portfolio Turnover [Text Block]rr_PortfolioTurnoverTextBlockThe 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 period, the Fund’s portfolio turnover rate was 64% of the average value of its portfolio.
Portfolio Turnover, Raterr_PortfolioTurnoverRate64.00%
Principal Investment Strategiesjif277751_PrincipalInvestmentStrategiesAbstract 
Strategy [Heading]rr_StrategyHeadingPRINCIPAL 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, 2011, they ranged from approximately $96 million to $3.1 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 assets in securities of companies having market capitalizations outside of the aforementioned market capitalization ranges or in cash or cash equivalents.

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 Risksjif277751_PrincipalInvestmentRisksAbstract 
Risk [Heading]rr_RiskHeadingPRINCIPAL 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.

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 tend to be 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.

Foreign Exposure Risk. The Fund may have exposure to foreign markets, including 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. 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.

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_RiskLoseMoneyThe biggest risk is that the Fund’s returns will vary, and you could lose money.
Risk Not Insured Depository Institution [Text]rr_RiskNotInsuredDepositoryInstitutionAn 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 INFORMATIONjif277751_FundPastPerformanceAbstract 
Bar Chart and Performance Table [Heading]rr_BarChartAndPerformanceTableHeadingPERFORMANCE 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.

• 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, without the effect of any 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, without the effect of any 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, 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 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.

Bar Chart Does Not Reflect Sales Loads [Text]rr_BarChartDoesNotReflectSalesLoadsThe 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.
Performance Additional Market Index [Text]rr_PerformanceAdditionalMarketIndexThe 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 Past Does Not Indicate Future [Text]rr_PerformancePastDoesNotIndicateFutureThe Fund’s past performance (before and after taxes) does not necessarily indicate how it will perform in the future.
Performance Table Closing [Text Block]rr_PerformanceTableClosingTextBlockUpdated performance information is available at janus.com/advisor/mutual-funds or by calling 1-877-335-2687.
Performance Availability Website Address [Text]rr_PerformanceAvailabilityWebSiteAddressjanus.com/advisor/mutual-funds
Performance Availability Phone [Text]rr_PerformanceAvailabilityPhone1-877-335-2687
Annual Total Returnsrr_BarChartTableAbstract 
Bar Chart [Heading]rr_BarChartHeadingAnnual Total Returns for Class T Shares (calendar year-end)
Bar Chart Closing [Text Block]rr_BarChartClosingTextBlock

Best Quarter: Fourth Quarter 2001 24.60%          Worst Quarter: Third Quarter 2002 -22.57%

Year to Date Return, Labelrr_YearToDateReturnLabelThe Fund’s year-to-date return as of the calendar quarter ended September 30, 2011 was -14.10%.
Bar Chart, Year to Date Return, Daterr_BarChartYearToDateReturnDateSep. 30, 2011
Bar Chart, Year to Date Returnrr_BarChartYearToDateReturn(14.10%)
Average Annual Total Returnsrr_AverageAnnualReturnAbstract 
Captionrr_AverageAnnualReturnCaptionAverage Annual Total Returns (periods ended 12/31/10)
Performance Table Narrativerr_PerformanceTableNarrativeTextBlock

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 Uses Highest Federal Raterr_PerformanceTableUsesHighestFederalRateAfter-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 Deferredrr_PerformanceTableNotRelevantToTaxDeferredActual 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_PerformanceTableOneClassOfAfterTaxShownAfter-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.
Perkins Small Cap Value Fund | Class A, C, S, I, R, T Shares | Class A
 
SHAREHOLDER FEESrr_ShareholderFeesAbstract 
Shareholder Fees Column [Text]rr_ShareholderFeesColumnNameClass A
Maximum Sales Charge (load) Imposed on Purchases (as a percentage of offering price)rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice5.75%
Maximum Deferred Sales Charge (load) (as a percentage of the lower of original purchase price or redemption proceeds)rr_MaximumDeferredSalesChargeOverOther none
ANNUAL FUND OPERATING EXPENSESrr_OperatingExpensesAbstract 
Operating Expenses Column [Text]rr_OperatingExpensesColumnNameClass A
Management Feesrr_ManagementFeesOverAssets0.81%
Distribution/Service (12b-1) Feesrr_DistributionAndService12b1FeesOverAssets0.25%
Other Expensesrr_OtherExpensesOverAssets0.20%
Total Annual Fund Operating Expensesrr_ExpensesOverAssets1.26%[32]
Fee Waiverrr_FeeWaiverOrReimbursementOverAssets none [32]
Net Annual Fund Operating Expenses After Fee Waiverrr_NetExpensesOverAssets1.26%[32]
EXAMPLE:rr_ExpenseExampleAbstract 
Expense Example, By Year, Column [Text]rr_ExpenseExampleByYearColumnNameClass A Shares
1 Yearrr_ExpenseExampleYear01696
3 Yearsrr_ExpenseExampleYear03952
5 Yearsrr_ExpenseExampleYear051,227
10 Yearsrr_ExpenseExampleYear102,010
Expense Example, No Redemption:rr_ExpenseExampleNoRedemptionAbstract 
Expense Example, No Redemption, By Year, Column [Text]rr_ExpenseExampleNoRedemptionByYearColumnNameClass A Shares
1 Yearrr_ExpenseExampleNoRedemptionYear01696
3 Yearsrr_ExpenseExampleNoRedemptionYear03952
5 Yearsrr_ExpenseExampleNoRedemptionYear051,227
10 Yearsrr_ExpenseExampleNoRedemptionYear102,010
Perkins Small Cap Value Fund | Class A, C, S, I, R, T Shares | Class C
 
SHAREHOLDER FEESrr_ShareholderFeesAbstract 
Shareholder Fees Column [Text]rr_ShareholderFeesColumnNameClass 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_MaximumDeferredSalesChargeOverOther1.00%
ANNUAL FUND OPERATING EXPENSESrr_OperatingExpensesAbstract 
Operating Expenses Column [Text]rr_OperatingExpensesColumnNameClass C
Management Feesrr_ManagementFeesOverAssets0.81%
Distribution/Service (12b-1) Feesrr_DistributionAndService12b1FeesOverAssets1.00%
Other Expensesrr_OtherExpensesOverAssets0.25%
Total Annual Fund Operating Expensesrr_ExpensesOverAssets2.06%[32]
Fee Waiverrr_FeeWaiverOrReimbursementOverAssets0.01%[32]
Net Annual Fund Operating Expenses After Fee Waiverrr_NetExpensesOverAssets2.05%[32]
EXAMPLE:rr_ExpenseExampleAbstract 
Expense Example, By Year, Column [Text]rr_ExpenseExampleByYearColumnNameClass C Shares
1 Yearrr_ExpenseExampleYear01309
3 Yearsrr_ExpenseExampleYear03646
5 Yearsrr_ExpenseExampleYear051,108
10 Yearsrr_ExpenseExampleYear102,390
Expense Example, No Redemption:rr_ExpenseExampleNoRedemptionAbstract 
Expense Example, No Redemption, By Year, Column [Text]rr_ExpenseExampleNoRedemptionByYearColumnNameClass C Shares
1 Yearrr_ExpenseExampleNoRedemptionYear01209
3 Yearsrr_ExpenseExampleNoRedemptionYear03646
5 Yearsrr_ExpenseExampleNoRedemptionYear051,108
10 Yearsrr_ExpenseExampleNoRedemptionYear102,390
Perkins Small Cap Value Fund | Class A, C, S, I, R, T Shares | Class S
 
SHAREHOLDER FEESrr_ShareholderFeesAbstract 
Shareholder Fees Column [Text]rr_ShareholderFeesColumnNameClass 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
ANNUAL FUND OPERATING EXPENSESrr_OperatingExpensesAbstract 
Operating Expenses Column [Text]rr_OperatingExpensesColumnNameClass S
Management Feesrr_ManagementFeesOverAssets0.81%
Distribution/Service (12b-1) Feesrr_DistributionAndService12b1FeesOverAssets0.25%
Other Expensesrr_OtherExpensesOverAssets0.30%
Total Annual Fund Operating Expensesrr_ExpensesOverAssets1.36%[32]
Fee Waiverrr_FeeWaiverOrReimbursementOverAssets none [32]
Net Annual Fund Operating Expenses After Fee Waiverrr_NetExpensesOverAssets1.36%[32]
EXAMPLE:rr_ExpenseExampleAbstract 
Expense Example, By Year, Column [Text]rr_ExpenseExampleByYearColumnNameClass S Shares
1 Yearrr_ExpenseExampleYear01138
3 Yearsrr_ExpenseExampleYear03431
5 Yearsrr_ExpenseExampleYear05745
10 Yearsrr_ExpenseExampleYear101,635
Expense Example, No Redemption:rr_ExpenseExampleNoRedemptionAbstract 
Expense Example, No Redemption, By Year, Column [Text]rr_ExpenseExampleNoRedemptionByYearColumnNameClass S Shares
1 Yearrr_ExpenseExampleNoRedemptionYear01138
3 Yearsrr_ExpenseExampleNoRedemptionYear03431
5 Yearsrr_ExpenseExampleNoRedemptionYear05745
10 Yearsrr_ExpenseExampleNoRedemptionYear101,635
Perkins Small Cap Value Fund | Class A, C, S, I, R, T Shares | Class I
 
SHAREHOLDER FEESrr_ShareholderFeesAbstract 
Shareholder Fees Column [Text]rr_ShareholderFeesColumnNameClass 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
ANNUAL FUND OPERATING EXPENSESrr_OperatingExpensesAbstract 
Operating Expenses Column [Text]rr_OperatingExpensesColumnNameClass I
Management Feesrr_ManagementFeesOverAssets0.81%
Distribution/Service (12b-1) Feesrr_DistributionAndService12b1FeesOverAssets none
Other Expensesrr_OtherExpensesOverAssets0.13%
Total Annual Fund Operating Expensesrr_ExpensesOverAssets0.94%[32]
Fee Waiverrr_FeeWaiverOrReimbursementOverAssets none [32]
Net Annual Fund Operating Expenses After Fee Waiverrr_NetExpensesOverAssets0.94%[32]
EXAMPLE:rr_ExpenseExampleAbstract 
Expense Example, By Year, Column [Text]rr_ExpenseExampleByYearColumnNameClass I Shares
1 Yearrr_ExpenseExampleYear0196
3 Yearsrr_ExpenseExampleYear03300
5 Yearsrr_ExpenseExampleYear05520
10 Yearsrr_ExpenseExampleYear101,155
Expense Example, No Redemption:rr_ExpenseExampleNoRedemptionAbstract 
Expense Example, No Redemption, By Year, Column [Text]rr_ExpenseExampleNoRedemptionByYearColumnNameClass I Shares
1 Yearrr_ExpenseExampleNoRedemptionYear0196
3 Yearsrr_ExpenseExampleNoRedemptionYear03300
5 Yearsrr_ExpenseExampleNoRedemptionYear05520
10 Yearsrr_ExpenseExampleNoRedemptionYear101,155
Perkins Small Cap Value Fund | Class A, C, S, I, R, T Shares | Class R
 
SHAREHOLDER FEESrr_ShareholderFeesAbstract 
Shareholder Fees Column [Text]rr_ShareholderFeesColumnNameClass 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
ANNUAL FUND OPERATING EXPENSESrr_OperatingExpensesAbstract 
Operating Expenses Column [Text]rr_OperatingExpensesColumnNameClass R
Management Feesrr_ManagementFeesOverAssets0.81%
Distribution/Service (12b-1) Feesrr_DistributionAndService12b1FeesOverAssets0.50%
Other Expensesrr_OtherExpensesOverAssets0.30%
Total Annual Fund Operating Expensesrr_ExpensesOverAssets1.61%[32]
Fee Waiverrr_FeeWaiverOrReimbursementOverAssets none [32]
Net Annual Fund Operating Expenses After Fee Waiverrr_NetExpensesOverAssets1.61%[32]
EXAMPLE:rr_ExpenseExampleAbstract 
Expense Example, By Year, Column [Text]rr_ExpenseExampleByYearColumnNameClass R Shares
1 Yearrr_ExpenseExampleYear01164
3 Yearsrr_ExpenseExampleYear03508
5 Yearsrr_ExpenseExampleYear05876
10 Yearsrr_ExpenseExampleYear101,911
Expense Example, No Redemption:rr_ExpenseExampleNoRedemptionAbstract 
Expense Example, No Redemption, By Year, Column [Text]rr_ExpenseExampleNoRedemptionByYearColumnNameClass R Shares
1 Yearrr_ExpenseExampleNoRedemptionYear01164
3 Yearsrr_ExpenseExampleNoRedemptionYear03508
5 Yearsrr_ExpenseExampleNoRedemptionYear05876
10 Yearsrr_ExpenseExampleNoRedemptionYear101,911
Perkins Small Cap Value Fund | Class A, C, S, I, R, T Shares | Class T
 
SHAREHOLDER FEESrr_ShareholderFeesAbstract 
Shareholder Fees Column [Text]rr_ShareholderFeesColumnNameClass 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
ANNUAL FUND OPERATING EXPENSESrr_OperatingExpensesAbstract 
Operating Expenses Column [Text]rr_OperatingExpensesColumnNameClass T
Management Feesrr_ManagementFeesOverAssets0.81%
Distribution/Service (12b-1) Feesrr_DistributionAndService12b1FeesOverAssets none
Other Expensesrr_OtherExpensesOverAssets0.30%
Total Annual Fund Operating Expensesrr_ExpensesOverAssets1.11%[32]
Fee Waiverrr_FeeWaiverOrReimbursementOverAssets none [32]
Net Annual Fund Operating Expenses After Fee Waiverrr_NetExpensesOverAssets1.11%[32]
EXAMPLE:rr_ExpenseExampleAbstract 
Expense Example, By Year, Column [Text]rr_ExpenseExampleByYearColumnNameClass T Shares
1 Yearrr_ExpenseExampleYear01113
3 Yearsrr_ExpenseExampleYear03353
5 Yearsrr_ExpenseExampleYear05612
10 Yearsrr_ExpenseExampleYear101,352
Expense Example, No Redemption:rr_ExpenseExampleNoRedemptionAbstract 
Expense Example, No Redemption, By Year, Column [Text]rr_ExpenseExampleNoRedemptionByYearColumnNameClass T Shares
1 Yearrr_ExpenseExampleNoRedemptionYear01113
3 Yearsrr_ExpenseExampleNoRedemptionYear03353
5 Yearsrr_ExpenseExampleNoRedemptionYear05612
10 Yearsrr_ExpenseExampleNoRedemptionYear101,352
Annual Total Returnsrr_BarChartTableAbstract 
2001rr_AnnualReturn200120.05%
2002rr_AnnualReturn2002(15.59%)
2003rr_AnnualReturn200336.78%
2004rr_AnnualReturn200413.57%
2005rr_AnnualReturn20058.90%
2006rr_AnnualReturn200612.37%
2007rr_AnnualReturn20072.97%
2008rr_AnnualReturn2008(21.79%)
2009rr_AnnualReturn200936.59%
2010rr_AnnualReturn201017.87%
Highest Quarterly Return, Labelrr_HighestQuarterlyReturnLabelBest Quarter:
Highest Quarterly Return, Daterr_BarChartHighestQuarterlyReturnDateDec. 31, 2001
Highest Quarterly Returnrr_BarChartHighestQuarterlyReturn24.60%
Lowest Quarterly Return, Labelrr_LowestQuarterlyReturnLabelWorst Quarter:
Lowest Quarterly Return, Daterr_BarChartLowestQuarterlyReturnDateSep. 30, 2002
Lowest Quarterly Returnrr_BarChartLowestQuarterlyReturn(22.57%)
Perkins Small Cap Value Fund | Class A, C, S, I, R, T Shares | Return Before Taxes | Class A
 
Average Annual Total Returnsrr_AverageAnnualReturnAbstract 
Columnrr_AverageAnnualReturnColumnNameClass A Shares
Labelrr_AverageAnnualReturnLabelReturn Before Taxes[3]
1 Yearrr_AverageAnnualReturnYear0111.01%
5 Yearsrr_AverageAnnualReturnYear056.31%
10 Yearsrr_AverageAnnualReturnYear108.67%
Perkins Small Cap Value Fund | Class A, C, S, I, R, T Shares | Return Before Taxes | Class C
 
Average Annual Total Returnsrr_AverageAnnualReturnAbstract 
Columnrr_AverageAnnualReturnColumnNameClass C Shares
Labelrr_AverageAnnualReturnLabelReturn Before Taxes[4]
1 Yearrr_AverageAnnualReturnYear0115.74%
5 Yearsrr_AverageAnnualReturnYear056.82%
10 Yearsrr_AverageAnnualReturnYear108.55%
Perkins Small Cap Value Fund | Class A, C, S, I, R, T Shares | Return Before Taxes | Class S
 
Average Annual Total Returnsrr_AverageAnnualReturnAbstract 
Columnrr_AverageAnnualReturnColumnNameClass S Shares
Labelrr_AverageAnnualReturnLabelReturn Before Taxes
1 Yearrr_AverageAnnualReturnYear0117.64%
5 Yearsrr_AverageAnnualReturnYear057.58%
10 Yearsrr_AverageAnnualReturnYear109.34%
Perkins Small Cap Value Fund | Class A, C, S, I, R, T Shares | Return Before Taxes | Class I
 
Average Annual Total Returnsrr_AverageAnnualReturnAbstract 
Columnrr_AverageAnnualReturnColumnNameClass I Shares
Labelrr_AverageAnnualReturnLabelReturn Before Taxes
1 Yearrr_AverageAnnualReturnYear0118.13%
5 Yearsrr_AverageAnnualReturnYear057.82%
10 Yearsrr_AverageAnnualReturnYear109.59%
Perkins Small Cap Value Fund | Class A, C, S, I, R, T Shares | Return Before Taxes | Class R
 
Average Annual Total Returnsrr_AverageAnnualReturnAbstract 
Columnrr_AverageAnnualReturnColumnNameClass R Shares
Labelrr_AverageAnnualReturnLabelReturn Before Taxes
1 Yearrr_AverageAnnualReturnYear0117.36%
5 Yearsrr_AverageAnnualReturnYear057.31%
10 Yearsrr_AverageAnnualReturnYear109.07%
Perkins Small Cap Value Fund | Class A, C, S, I, R, T Shares | Return Before Taxes | Class T
 
Average Annual Total Returnsrr_AverageAnnualReturnAbstract 
Columnrr_AverageAnnualReturnColumnNameClass T Shares
Labelrr_AverageAnnualReturnLabelReturn Before Taxes
1 Yearrr_AverageAnnualReturnYear0117.87%
5 Yearsrr_AverageAnnualReturnYear057.82%
10 Yearsrr_AverageAnnualReturnYear109.59%
Perkins Small Cap Value Fund | Class A, C, S, I, R, T Shares | Return After Taxes on Distributions | Class T
 
Average Annual Total Returnsrr_AverageAnnualReturnAbstract 
Columnrr_AverageAnnualReturnColumnNameClass T Shares
Labelrr_AverageAnnualReturnLabelReturn After Taxes on Distributions
1 Yearrr_AverageAnnualReturnYear0117.37%
5 Yearsrr_AverageAnnualReturnYear055.89%
10 Yearsrr_AverageAnnualReturnYear107.67%
Perkins Small Cap Value Fund | Class A, C, S, I, R, T Shares | Return After Taxes on Distributions and Sale of Fund Shares | Class T
 
Average Annual Total Returnsrr_AverageAnnualReturnAbstract 
Columnrr_AverageAnnualReturnColumnNameClass T Shares
Labelrr_AverageAnnualReturnLabelReturn After Taxes on Distributions and Sale of Fund Shares[5]
1 Yearrr_AverageAnnualReturnYear0112.28%
5 Yearsrr_AverageAnnualReturnYear056.09%
10 Yearsrr_AverageAnnualReturnYear107.70%
Perkins Small Cap Value Fund | Class A, C, S, I, R, T Shares | Russell 2000® Value Index
 
Average Annual Total Returnsrr_AverageAnnualReturnAbstract 
Labelrr_AverageAnnualReturnLabelRussell 2000® Value Index
Index No Deduction for Fees, Expenses, Taxes [Text]rr_IndexNoDeductionForFeesExpensesTaxes(reflects no deduction for expenses, fees, or taxes)
1 Yearrr_AverageAnnualReturnYear0124.50%
5 Yearsrr_AverageAnnualReturnYear053.52%
10 Yearsrr_AverageAnnualReturnYear108.42%
Perkins Small Cap Value Fund | Class D Shares
 
Risk/Return:rr_RiskReturnAbstract 
Risk/Return [Heading]rr_RiskReturnHeadingFUND SUMMARY Perkins Small Cap Value Fund
Objective [Heading]rr_ObjectiveHeadingINVESTMENT OBJECTIVE
Objective, Primary [Text Block]rr_ObjectivePrimaryTextBlockPerkins Small Cap Value Fund seeks capital appreciation.
FEES AND EXPENSES OF THE FUNDjif277751_FundFeesAndExpensesAbstract 
Expense [Heading]rr_ExpenseHeadingFEES AND EXPENSES OF THE FUND
Expense Narrative [Text Block]rr_ExpenseNarrativeTextBlockThis table describes the fees and expenses that you may pay if you buy and hold Shares of the Fund.
ANNUAL FUND OPERATING EXPENSESrr_OperatingExpensesAbstract 
Operating Expenses Caption [Text]rr_OperatingExpensesCaptionANNUAL 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 Terminationrr_FeeWaiverOrReimbursementOverAssetsDateOfTerminationNovember 1, 2012
EXAMPLE:rr_ExpenseExampleAbstract 
Expense Example [Heading]rr_ExpenseExampleHeadingEXAMPLE:
Expense Example Narrative [Text Block]rr_ExpenseExampleNarrativeTextBlockThe 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 [Heading]rr_ExpenseExampleByYearHeadingThe 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:
Portfolio Turnover:jif277751_PortfolioTurnoverAltAbstract 
Portfolio Turnover [Heading]rr_PortfolioTurnoverHeadingPortfolio Turnover:
Portfolio Turnover [Text Block]rr_PortfolioTurnoverTextBlockThe 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 period, the Fund’s portfolio turnover rate was 64% of the average value of its portfolio.
Portfolio Turnover, Raterr_PortfolioTurnoverRate64.00%
Principal Investment Strategiesjif277751_PrincipalInvestmentStrategiesAbstract 
Strategy [Heading]rr_StrategyHeadingPRINCIPAL 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, 2011, they ranged from approximately $96 million to $3.1 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 assets in securities of companies having market capitalizations outside of the aforementioned market capitalization ranges or in cash or cash equivalents.

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 Risksjif277751_PrincipalInvestmentRisksAbstract 
Risk [Heading]rr_RiskHeadingPRINCIPAL 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.

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 tend to be 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.

Foreign Exposure Risk. The Fund may have exposure to foreign markets, including 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. 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.

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_RiskLoseMoneyThe biggest risk is that the Fund’s returns will vary, and you could lose money.
Risk Not Insured Depository Institution [Text]rr_RiskNotInsuredDepositoryInstitutionAn 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 INFORMATIONjif277751_FundPastPerformanceAbstract 
Bar Chart and Performance Table [Heading]rr_BarChartAndPerformanceTableHeadingPERFORMANCE 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 December 31, 2009, 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 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_PerformanceAdditionalMarketIndexThe 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 Past Does Not Indicate Future [Text]rr_PerformancePastDoesNotIndicateFutureThe Fund’s past performance (before and after taxes) does not necessarily indicate how it will perform in the future.
Performance Table Closing [Text Block]rr_PerformanceTableClosingTextBlockUpdated performance information is available at janus.com/allfunds or by calling 1-800-525-3713.
Performance Availability Website Address [Text]rr_PerformanceAvailabilityWebSiteAddress janus.com/allfunds
Performance Availability Phone [Text]rr_PerformanceAvailabilityPhone1-800-525-3713
Annual Total Returnsrr_BarChartTableAbstract 
Bar Chart [Heading]rr_BarChartHeadingAnnual Total Returns for Class D Shares (calendar year-end)
Bar Chart Closing [Text Block]rr_BarChartClosingTextBlock

Best Quarter:  Fourth Quarter 2001  24.60%          Worst Quarter:  Third Quarter 2002  -22.57%

Year to Date Return, Labelrr_YearToDateReturnLabelThe Fund’s year-to-date return as of the calendar quarter ended September 30, 2011 was -14.05%.
Bar Chart, Year to Date Return, Daterr_BarChartYearToDateReturnDateSep. 30, 2011
Bar Chart, Year to Date Returnrr_BarChartYearToDateReturn(14.05%)
Average Annual Total Returnsrr_AverageAnnualReturnAbstract 
Captionrr_AverageAnnualReturnCaptionAverage Annual Total Returns (periods ended 12/31/10)
Performance Table Narrativerr_PerformanceTableNarrativeTextBlockAfter-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 Uses Highest Federal Raterr_PerformanceTableUsesHighestFederalRateAfter-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 Deferredrr_PerformanceTableNotRelevantToTaxDeferredActual 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.
Perkins Small Cap Value Fund | Class D Shares | Class D
 
ANNUAL FUND OPERATING EXPENSESrr_OperatingExpensesAbstract 
Operating Expenses Column [Text]rr_OperatingExpensesColumnNameClass D
Management Feesrr_ManagementFeesOverAssets0.81%
Other Expensesrr_OtherExpensesOverAssets0.19%
Total Annual Fund Operating Expensesrr_ExpensesOverAssets1.00%[33]
EXAMPLE:rr_ExpenseExampleAbstract 
Expense Example, By Year, Column [Text]rr_ExpenseExampleByYearColumnNameClass D Shares
1 Yearrr_ExpenseExampleYear01102
3 Yearsrr_ExpenseExampleYear03318
5 Yearsrr_ExpenseExampleYear05552
10 Yearsrr_ExpenseExampleYear101,225
Annual Total Returnsrr_BarChartTableAbstract 
2001rr_AnnualReturn200120.05%
2002rr_AnnualReturn2002(15.59%)
2003rr_AnnualReturn200336.78%
2004rr_AnnualReturn200413.57%
2005rr_AnnualReturn20058.90%
2006rr_AnnualReturn200612.37%
2007rr_AnnualReturn20072.97%
2008rr_AnnualReturn2008(21.79%)
2009rr_AnnualReturn200936.59%
2010rr_AnnualReturn201018.00%
Highest Quarterly Return, Labelrr_HighestQuarterlyReturnLabelBest Quarter:
Highest Quarterly Return, Daterr_BarChartHighestQuarterlyReturnDateDec. 31, 2001
Highest Quarterly Returnrr_BarChartHighestQuarterlyReturn24.60%
Lowest Quarterly Return, Labelrr_LowestQuarterlyReturnLabelWorst Quarter:
Lowest Quarterly Return, Daterr_BarChartLowestQuarterlyReturnDateSep. 30, 2002
Lowest Quarterly Returnrr_BarChartLowestQuarterlyReturn(22.57%)
Perkins Small Cap Value Fund | Class D Shares | Return Before Taxes | Class D
 
Average Annual Total Returnsrr_AverageAnnualReturnAbstract 
Columnrr_AverageAnnualReturnColumnNameClass D Shares
Labelrr_AverageAnnualReturnLabelReturn Before Taxes
1 Yearrr_AverageAnnualReturnYear0118.00%
5 Yearsrr_AverageAnnualReturnYear057.84%
10 Yearsrr_AverageAnnualReturnYear109.60%
Perkins Small Cap Value Fund | Class D Shares | Return After Taxes on Distributions | Class D
 
Average Annual Total Returnsrr_AverageAnnualReturnAbstract 
Columnrr_AverageAnnualReturnColumnNameClass D Shares
Labelrr_AverageAnnualReturnLabelReturn After Taxes on Distributions
1 Yearrr_AverageAnnualReturnYear0117.49%
5 Yearsrr_AverageAnnualReturnYear055.91%
10 Yearsrr_AverageAnnualReturnYear107.68%
Perkins Small Cap Value Fund | Class D Shares | Return After Taxes on Distributions and Sale of Fund Shares | Class D
 
Average Annual Total Returnsrr_AverageAnnualReturnAbstract 
Columnrr_AverageAnnualReturnColumnNameClass D Shares
Labelrr_AverageAnnualReturnLabelReturn After Taxes on Distributions and Sale of Fund Shares[5]
1 Yearrr_AverageAnnualReturnYear0112.37%
5 Yearsrr_AverageAnnualReturnYear056.10%
10 Yearsrr_AverageAnnualReturnYear107.71%
Perkins Small Cap Value Fund | Class D Shares | Russell 2000® Value Index
 
Average Annual Total Returnsrr_AverageAnnualReturnAbstract 
Labelrr_AverageAnnualReturnLabelRussell 2000® Value Index
Index No Deduction for Fees, Expenses, Taxes [Text]rr_IndexNoDeductionForFeesExpensesTaxes(reflects no deduction for expenses, fees, or taxes)
1 Yearrr_AverageAnnualReturnYear0124.50%
5 Yearsrr_AverageAnnualReturnYear053.52%
10 Yearsrr_AverageAnnualReturnYear108.42%
Perkins Small Cap Value Fund | Class L Shares
 
Risk/Return:rr_RiskReturnAbstract 
Risk/Return [Heading]rr_RiskReturnHeadingFUND SUMMARY Perkins Small Cap Value Fund
Objective [Heading]rr_ObjectiveHeadingINVESTMENT OBJECTIVE
Objective, Primary [Text Block]rr_ObjectivePrimaryTextBlockPerkins Small Cap Value Fund seeks capital appreciation.
FEES AND EXPENSES OF THE FUNDjif277751_FundFeesAndExpensesAbstract 
Expense [Heading]rr_ExpenseHeadingFEES AND EXPENSES OF THE FUND
Expense Narrative [Text Block]rr_ExpenseNarrativeTextBlockThis table describes the fees and expenses that you may pay if you buy and hold Shares of the Fund.
ANNUAL FUND OPERATING EXPENSESrr_OperatingExpensesAbstract 
Operating Expenses Caption [Text]rr_OperatingExpensesCaptionANNUAL 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 Terminationrr_FeeWaiverOrReimbursementOverAssetsDateOfTerminationNovember 1, 2012
EXAMPLE:rr_ExpenseExampleAbstract 
Expense Example [Heading]rr_ExpenseExampleHeadingEXAMPLE:
Expense Example Narrative [Text Block]rr_ExpenseExampleNarrativeTextBlockThe 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 [Heading]rr_ExpenseExampleByYearHeadingThe 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:
Portfolio Turnover:jif277751_PortfolioTurnoverAltAbstract 
Portfolio Turnover [Heading]rr_PortfolioTurnoverHeadingPortfolio Turnover:
Portfolio Turnover [Text Block]rr_PortfolioTurnoverTextBlockThe 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 period, the Fund’s portfolio turnover rate was 64% of the average value of its portfolio.
Portfolio Turnover, Raterr_PortfolioTurnoverRate64.00%
Principal Investment Strategiesjif277751_PrincipalInvestmentStrategiesAbstract 
Strategy [Heading]rr_StrategyHeadingPRINCIPAL 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, 2011, they ranged from approximately $96 million to $3.1 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 assets in securities of companies having market capitalizations outside of the aforementioned market capitalization ranges or in cash or cash equivalents.

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 Risksjif277751_PrincipalInvestmentRisksAbstract 
Risk [Heading]rr_RiskHeadingPRINCIPAL 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.

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 tend to be 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.

Foreign Exposure Risk. The Fund may have exposure to foreign markets, including 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. 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.

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_RiskLoseMoneyThe biggest risk is that the Fund’s returns will vary, and you could lose money.
Risk Not Insured Depository Institution [Text]rr_RiskNotInsuredDepositoryInstitutionAn 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 INFORMATIONjif277751_FundPastPerformanceAbstract 
Bar Chart and Performance Table [Heading]rr_BarChartAndPerformanceTableHeadingPERFORMANCE 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_PerformanceAdditionalMarketIndexThe 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 Past Does Not Indicate Future [Text]rr_PerformancePastDoesNotIndicateFutureThe Fund’s past performance (before and after taxes) does not necessarily indicate how it will perform in the future.
Performance Table Closing [Text Block]rr_PerformanceTableClosingTextBlockUpdated performance information is available at janus.com/advisor/mutual-funds or by calling 1-877-335-2687.
Performance Availability Website Address [Text]rr_PerformanceAvailabilityWebSiteAddressjanus.com/advisor/mutual-funds
Performance Availability Phone [Text]rr_PerformanceAvailabilityPhone1-877-335-2687
Annual Total Returnsrr_BarChartTableAbstract 
Bar Chart [Heading]rr_BarChartHeadingAnnual Total Returns for Class L Shares (calendar year-end)
Bar Chart Closing [Text Block]rr_BarChartClosingTextBlock

Best Quarter:  Fourth Quarter 2001  24.60%          Worst Quarter:  Third Quarter 2002  -22.57%

Year to Date Return, Labelrr_YearToDateReturnLabelThe Fund's year-to-date return as of the calendar quarter ended September 30, 2011 was -13.93%.
Bar Chart, Year to Date Return, Daterr_BarChartYearToDateReturnDateSep. 30, 2011
Bar Chart, Year to Date Returnrr_BarChartYearToDateReturn(13.93%)
Average Annual Total Returnsrr_AverageAnnualReturnAbstract 
Captionrr_AverageAnnualReturnCaptionAverage Annual Total Returns (periods ended 12/31/10)
Performance Table Narrativerr_PerformanceTableNarrativeTextBlockAfter-tax returns are calculated using distributions for the Fund’s Class L Shares (formerly named Institutional Shares) for the period April 21, 2003 to December 31, 2009; 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 Uses Highest Federal Raterr_PerformanceTableUsesHighestFederalRateAfter-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 Deferredrr_PerformanceTableNotRelevantToTaxDeferredActual 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.
Perkins Small Cap Value Fund | Class L Shares | Class L
 
ANNUAL FUND OPERATING EXPENSESrr_OperatingExpensesAbstract 
Operating Expenses Column [Text]rr_OperatingExpensesColumnNameClass L
Management Feesrr_ManagementFeesOverAssets0.81%
Other Expensesrr_OtherExpensesOverAssets0.28%
Total Annual Fund Operating Expensesrr_ExpensesOverAssets1.09%[33]
EXAMPLE:rr_ExpenseExampleAbstract 
Expense Example, By Year, Column [Text]rr_ExpenseExampleByYearColumnNameClass L Shares
1 Yearrr_ExpenseExampleYear01111
3 Yearsrr_ExpenseExampleYear03347
5 Yearsrr_ExpenseExampleYear05601
10 Yearsrr_ExpenseExampleYear101,329
Annual Total Returnsrr_BarChartTableAbstract 
2001rr_AnnualReturn200120.42%
2002rr_AnnualReturn2002(15.33%)
2003rr_AnnualReturn200337.18%
2004rr_AnnualReturn200413.80%
2005rr_AnnualReturn20059.14%
2006rr_AnnualReturn200612.57%
2007rr_AnnualReturn20073.21%
2008rr_AnnualReturn2008(21.63%)
2009rr_AnnualReturn200936.91%
2010rr_AnnualReturn201018.18%
Highest Quarterly Return, Labelrr_HighestQuarterlyReturnLabelBest Quarter:
Highest Quarterly Return, Daterr_BarChartHighestQuarterlyReturnDateDec. 31, 2001
Highest Quarterly Returnrr_BarChartHighestQuarterlyReturn24.60%
Lowest Quarterly Return, Labelrr_LowestQuarterlyReturnLabelWorst Quarter:
Lowest Quarterly Return, Daterr_BarChartLowestQuarterlyReturnDateSep. 30, 2002
Lowest Quarterly Returnrr_BarChartLowestQuarterlyReturn(22.57%)
Perkins Small Cap Value Fund | Class L Shares | Return Before Taxes | Class L
 
Average Annual Total Returnsrr_AverageAnnualReturnAbstract 
Columnrr_AverageAnnualReturnColumnNameClass L Shares
Labelrr_AverageAnnualReturnLabelReturn Before Taxes
1 Yearrr_AverageAnnualReturnYear0118.18%
5 Yearsrr_AverageAnnualReturnYear058.06%
10 Yearsrr_AverageAnnualReturnYear109.85%
Perkins Small Cap Value Fund | Class L Shares | Return After Taxes on Distributions | Class L
 
Average Annual Total Returnsrr_AverageAnnualReturnAbstract 
Columnrr_AverageAnnualReturnColumnNameClass L Shares
Labelrr_AverageAnnualReturnLabelReturn After Taxes on Distributions
1 Yearrr_AverageAnnualReturnYear0117.67%
5 Yearsrr_AverageAnnualReturnYear056.10%
10 Yearsrr_AverageAnnualReturnYear107.89%
Perkins Small Cap Value Fund | Class L Shares | Return After Taxes on Distributions and Sale of Fund Shares | Class L
 
Average Annual Total Returnsrr_AverageAnnualReturnAbstract 
Columnrr_AverageAnnualReturnColumnNameClass L Shares
Labelrr_AverageAnnualReturnLabelReturn After Taxes on Distributions and Sale of Fund Shares[5]
1 Yearrr_AverageAnnualReturnYear0112.49%
5 Yearsrr_AverageAnnualReturnYear056.27%
10 Yearsrr_AverageAnnualReturnYear107.91%
Perkins Small Cap Value Fund | Class L Shares | Russell 2000® Value Index
 
Average Annual Total Returnsrr_AverageAnnualReturnAbstract 
Labelrr_AverageAnnualReturnLabelRussell 2000® Value Index
Index No Deduction for Fees, Expenses, Taxes [Text]rr_IndexNoDeductionForFeesExpensesTaxes(reflects no deduction for expenses, fees, or taxes)
1 Yearrr_AverageAnnualReturnYear0124.50%
5 Yearsrr_AverageAnnualReturnYear053.52%
10 Yearsrr_AverageAnnualReturnYear108.42%
Perkins Value Plus Income Fund | Class A, C, S, I, T Shares
 
Risk/Return:rr_RiskReturnAbstract 
Risk/Return [Heading]rr_RiskReturnHeadingFUND SUMMARY Perkins Value Plus Income Fund
Objective [Heading]rr_ObjectiveHeadingINVESTMENT OBJECTIVE
Objective, Primary [Text Block]rr_ObjectivePrimaryTextBlockPerkins Value Plus Income Fund seeks capital appreciation and current income.
FEES AND EXPENSES OF THE FUNDjif277751_FundFeesAndExpensesAbstract 
Expense [Heading]rr_ExpenseHeadingFEES AND EXPENSES OF THE FUND
Expense Narrative [Text Block]rr_ExpenseNarrativeTextBlockThis 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.
Expense Breakpoint Discountsjif277751_ExpenseBreakpointDiscountsAbstract 
Expense Breakpoint Discounts [Text]rr_ExpenseBreakpointDiscountsFor 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 48 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_ExpenseBreakpointMinimumInvestmentRequiredAmount50,000
SHAREHOLDER FEESrr_ShareholderFeesAbstract 
Shareholder Fees Caption [Text]rr_ShareholderFeesCaptionSHAREHOLDER FEES (fees paid directly from your investment)
ANNUAL FUND OPERATING EXPENSESrr_OperatingExpensesAbstract 
Operating Expenses Caption [Text]rr_OperatingExpensesCaptionANNUAL 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 Terminationrr_FeeWaiverOrReimbursementOverAssetsDateOfTerminationNovember 1, 2012
EXAMPLE:rr_ExpenseExampleAbstract 
Expense Example [Heading]rr_ExpenseExampleHeadingEXAMPLE:
Expense Example Narrative [Text Block]rr_ExpenseExampleNarrativeTextBlockThe 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 [Heading]rr_ExpenseExampleByYearHeadingThe 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 by, Year, Caption [Text]rr_ExpenseExampleByYearCaptionIf Shares are redeemed:
Expense Example, No Redemption:rr_ExpenseExampleNoRedemptionAbstract 
Expense Example, No Redemption, By Year, Caption [Text]rr_ExpenseExampleNoRedemptionByYearCaptionIf Shares are not redeemed:
Portfolio Turnover:jif277751_PortfolioTurnoverAltAbstract 
Portfolio Turnover [Heading]rr_PortfolioTurnoverHeadingPortfolio Turnover:
Portfolio Turnover [Text Block]rr_PortfolioTurnoverTextBlockThe 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 period, the Fund’s portfolio turnover rate was 93% of the average value of its portfolio.
Portfolio Turnover, Raterr_PortfolioTurnoverRate93.00%
Principal Investment Strategiesjif277751_PrincipalInvestmentStrategiesAbstract 
Strategy [Heading]rr_StrategyHeadingPRINCIPAL 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, and zero-coupon bonds), 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 an underlying asset, such as equity securities, bonds, commodities, currencies, interest rates, or market indices, as substitutes for securities in which the Fund invests. The Fund has invested in and may continue to invest in derivative instruments (by taking long and/or short positions) including, but not limited to, put and call options, particularly on market indices, for hedging purposes (to offset risks associated with an investment, currency exposure or market conditions). The Fund may invest in other types of derivatives and may do so for other purposes including 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. For more information on the Fund’s use of derivatives, refer to the Fund’s shareholder reports and Form N-Q reports, which are filed with the Securities and Exchange Commission.

The Fund’s adviser 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. The Fund’s subadviser 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.

Principal Investment Risksjif277751_PrincipalInvestmentRisksAbstract 
Risk [Heading]rr_RiskHeadingPRINCIPAL 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.

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 their value 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.

Mortgage-Backed Securities Risk. Mortgage-backed securities tend to be more sensitive to changes in interest rates than other types of 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.

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.

Foreign Exposure Risk. The Fund may have exposure to foreign markets, including 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. 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.

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 can be substantially greater than the derivative’s original cost, and can therefore involve 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.

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_RiskLoseMoneyThe biggest risk is that the Fund’s returns and yields will vary, and you could lose money.
Risk Not Insured Depository Institution [Text]rr_RiskNotInsuredDepositoryInstitutionAn 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 INFORMATIONjif277751_FundPastPerformanceAbstract 
Bar Chart and Performance Table [Heading]rr_BarChartAndPerformanceTableHeadingPERFORMANCE INFORMATION
Performance Narrative [Text Block]rr_PerformanceNarrativeTextBlockThe Fund does not have a full calendar year of operations. Performance information for certain periods will be included in the Fund’s first annual and/or semiannual report.
Performance One Year or Less [Text]rr_PerformanceOneYearOrLessThe Fund does not have a full calendar year of operations.
Perkins Value Plus Income Fund | Class A, C, S, I, T Shares | Class A
 
SHAREHOLDER FEESrr_ShareholderFeesAbstract 
Shareholder Fees Column [Text]rr_ShareholderFeesColumnNameClass A
Maximum Sales Charge (load) Imposed on Purchases (as a percentage of offering price)rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice5.75%
Maximum Deferred Sales Charge (load) (as a percentage of the lower of original purchase price or redemption proceeds)rr_MaximumDeferredSalesChargeOverOther none
ANNUAL FUND OPERATING EXPENSESrr_OperatingExpensesAbstract 
Operating Expenses Column [Text]rr_OperatingExpensesColumnNameClass A
Management Feesrr_ManagementFeesOverAssets0.60%
Distribution/Service (12b-1) Feesrr_DistributionAndService12b1FeesOverAssets0.25%
Other Expensesrr_OtherExpensesOverAssets1.02%
Total Annual Fund Operating Expensesrr_ExpensesOverAssets1.87%[34]
Fee Waiverrr_FeeWaiverOrReimbursementOverAssets0.84%[34]
Net Annual Fund Operating Expenses After Fee Waiverrr_NetExpensesOverAssets1.03%[34]
EXAMPLE:rr_ExpenseExampleAbstract 
Expense Example, By Year, Column [Text]rr_ExpenseExampleByYearColumnNameClass A Shares
1 Yearrr_ExpenseExampleYear01754
3 Yearsrr_ExpenseExampleYear031,129
5 Yearsrr_ExpenseExampleYear051,528
10 Yearsrr_ExpenseExampleYear102,639
Expense Example, No Redemption:rr_ExpenseExampleNoRedemptionAbstract 
Expense Example, No Redemption, By Year, Column [Text]rr_ExpenseExampleNoRedemptionByYearColumnNameClass A Shares
1 Yearrr_ExpenseExampleNoRedemptionYear01754
3 Yearsrr_ExpenseExampleNoRedemptionYear031,129
5 Yearsrr_ExpenseExampleNoRedemptionYear051,528
10 Yearsrr_ExpenseExampleNoRedemptionYear102,639
Perkins Value Plus Income Fund | Class A, C, S, I, T Shares | Class C
 
SHAREHOLDER FEESrr_ShareholderFeesAbstract 
Shareholder Fees Column [Text]rr_ShareholderFeesColumnNameClass 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_MaximumDeferredSalesChargeOverOther1.00%
ANNUAL FUND OPERATING EXPENSESrr_OperatingExpensesAbstract 
Operating Expenses Column [Text]rr_OperatingExpensesColumnNameClass C
Management Feesrr_ManagementFeesOverAssets0.60%
Distribution/Service (12b-1) Feesrr_DistributionAndService12b1FeesOverAssets1.00%
Other Expensesrr_OtherExpensesOverAssets1.03%
Total Annual Fund Operating Expensesrr_ExpensesOverAssets2.63%[34]
Fee Waiverrr_FeeWaiverOrReimbursementOverAssets0.85%[34]
Net Annual Fund Operating Expenses After Fee Waiverrr_NetExpensesOverAssets1.78%[34]
EXAMPLE:rr_ExpenseExampleAbstract 
Expense Example, By Year, Column [Text]rr_ExpenseExampleByYearColumnNameClass C Shares
1 Yearrr_ExpenseExampleYear01366
3 Yearsrr_ExpenseExampleYear03817
5 Yearsrr_ExpenseExampleYear051,395
10 Yearsrr_ExpenseExampleYear102,964
Expense Example, No Redemption:rr_ExpenseExampleNoRedemptionAbstract 
Expense Example, No Redemption, By Year, Column [Text]rr_ExpenseExampleNoRedemptionByYearColumnNameClass C Shares
1 Yearrr_ExpenseExampleNoRedemptionYear01266
3 Yearsrr_ExpenseExampleNoRedemptionYear03817
5 Yearsrr_ExpenseExampleNoRedemptionYear051,395
10 Yearsrr_ExpenseExampleNoRedemptionYear102,964
Perkins Value Plus Income Fund | Class A, C, S, I, T Shares | Class S
 
SHAREHOLDER FEESrr_ShareholderFeesAbstract 
Shareholder Fees Column [Text]rr_ShareholderFeesColumnNameClass 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
ANNUAL FUND OPERATING EXPENSESrr_OperatingExpensesAbstract 
Operating Expenses Column [Text]rr_OperatingExpensesColumnNameClass S
Management Feesrr_ManagementFeesOverAssets0.60%
Distribution/Service (12b-1) Feesrr_DistributionAndService12b1FeesOverAssets0.25%
Other Expensesrr_OtherExpensesOverAssets1.28%
Total Annual Fund Operating Expensesrr_ExpensesOverAssets2.13%[34]
Fee Waiverrr_FeeWaiverOrReimbursementOverAssets0.84%[34]
Net Annual Fund Operating Expenses After Fee Waiverrr_NetExpensesOverAssets1.29%[34]
EXAMPLE:rr_ExpenseExampleAbstract 
Expense Example, By Year, Column [Text]rr_ExpenseExampleByYearColumnNameClass S Shares
1 Yearrr_ExpenseExampleYear01216
3 Yearsrr_ExpenseExampleYear03667
5 Yearsrr_ExpenseExampleYear051,144
10 Yearsrr_ExpenseExampleYear102,462
Expense Example, No Redemption:rr_ExpenseExampleNoRedemptionAbstract 
Expense Example, No Redemption, By Year, Column [Text]rr_ExpenseExampleNoRedemptionByYearColumnNameClass S Shares
1 Yearrr_ExpenseExampleNoRedemptionYear01216
3 Yearsrr_ExpenseExampleNoRedemptionYear03667
5 Yearsrr_ExpenseExampleNoRedemptionYear051,144
10 Yearsrr_ExpenseExampleNoRedemptionYear102,462
Perkins Value Plus Income Fund | Class A, C, S, I, T Shares | Class I
 
SHAREHOLDER FEESrr_ShareholderFeesAbstract 
Shareholder Fees Column [Text]rr_ShareholderFeesColumnNameClass 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
ANNUAL FUND OPERATING EXPENSESrr_OperatingExpensesAbstract 
Operating Expenses Column [Text]rr_OperatingExpensesColumnNameClass I
Management Feesrr_ManagementFeesOverAssets0.60%
Distribution/Service (12b-1) Feesrr_DistributionAndService12b1FeesOverAssets none
Other Expensesrr_OtherExpensesOverAssets1.02%
Total Annual Fund Operating Expensesrr_ExpensesOverAssets1.62%[34]
Fee Waiverrr_FeeWaiverOrReimbursementOverAssets0.85%[34]
Net Annual Fund Operating Expenses After Fee Waiverrr_NetExpensesOverAssets0.77%[34]
EXAMPLE:rr_ExpenseExampleAbstract 
Expense Example, By Year, Column [Text]rr_ExpenseExampleByYearColumnNameClass I Shares
1 Yearrr_ExpenseExampleYear01165
3 Yearsrr_ExpenseExampleYear03511
5 Yearsrr_ExpenseExampleYear05881
10 Yearsrr_ExpenseExampleYear101,922
Expense Example, No Redemption:rr_ExpenseExampleNoRedemptionAbstract 
Expense Example, No Redemption, By Year, Column [Text]rr_ExpenseExampleNoRedemptionByYearColumnNameClass I Shares
1 Yearrr_ExpenseExampleNoRedemptionYear01165
3 Yearsrr_ExpenseExampleNoRedemptionYear03511
5 Yearsrr_ExpenseExampleNoRedemptionYear05881
10 Yearsrr_ExpenseExampleNoRedemptionYear101,922
Perkins Value Plus Income Fund | Class A, C, S, I, T Shares | Class T
 
SHAREHOLDER FEESrr_ShareholderFeesAbstract 
Shareholder Fees Column [Text]rr_ShareholderFeesColumnNameClass 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
ANNUAL FUND OPERATING EXPENSESrr_OperatingExpensesAbstract 
Operating Expenses Column [Text]rr_OperatingExpensesColumnNameClass T
Management Feesrr_ManagementFeesOverAssets0.60%
Distribution/Service (12b-1) Feesrr_DistributionAndService12b1FeesOverAssets none
Other Expensesrr_OtherExpensesOverAssets1.27%
Total Annual Fund Operating Expensesrr_ExpensesOverAssets1.87%[34]
Fee Waiverrr_FeeWaiverOrReimbursementOverAssets0.84%[34]
Net Annual Fund Operating Expenses After Fee Waiverrr_NetExpensesOverAssets1.03%[34]
EXAMPLE:rr_ExpenseExampleAbstract 
Expense Example, By Year, Column [Text]rr_ExpenseExampleByYearColumnNameClass T Shares
1 Yearrr_ExpenseExampleYear01190
3 Yearsrr_ExpenseExampleYear03588
5 Yearsrr_ExpenseExampleYear051,011
10 Yearsrr_ExpenseExampleYear102,190
Expense Example, No Redemption:rr_ExpenseExampleNoRedemptionAbstract 
Expense Example, No Redemption, By Year, Column [Text]rr_ExpenseExampleNoRedemptionByYearColumnNameClass T Shares
1 Yearrr_ExpenseExampleNoRedemptionYear01190
3 Yearsrr_ExpenseExampleNoRedemptionYear03588
5 Yearsrr_ExpenseExampleNoRedemptionYear051,011
10 Yearsrr_ExpenseExampleNoRedemptionYear102,190
Perkins Value Plus Income Fund | Class D Shares
 
Risk/Return:rr_RiskReturnAbstract 
Risk/Return [Heading]rr_RiskReturnHeadingFUND SUMMARY Perkins Value Plus Income Fund
Objective [Heading]rr_ObjectiveHeadingINVESTMENT OBJECTIVE
Objective, Primary [Text Block]rr_ObjectivePrimaryTextBlockPerkins Value Plus Income Fund seeks capital appreciation and current income.
FEES AND EXPENSES OF THE FUNDjif277751_FundFeesAndExpensesAbstract 
Expense [Heading]rr_ExpenseHeadingFEES AND EXPENSES OF THE FUND
Expense Narrative [Text Block]rr_ExpenseNarrativeTextBlockThis table describes the fees and expenses that you may pay if you buy and hold Shares of the Fund.
ANNUAL FUND OPERATING EXPENSESrr_OperatingExpensesAbstract 
Operating Expenses Caption [Text]rr_OperatingExpensesCaptionANNUAL 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 Terminationrr_FeeWaiverOrReimbursementOverAssetsDateOfTerminationNovember 1, 2012
EXAMPLE:rr_ExpenseExampleAbstract 
Expense Example [Heading]rr_ExpenseExampleHeadingEXAMPLE:
Expense Example Narrative [Text Block]rr_ExpenseExampleNarrativeTextBlockThe 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 [Heading]rr_ExpenseExampleByYearHeadingThe 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:
Portfolio Turnover:jif277751_PortfolioTurnoverAltAbstract 
Portfolio Turnover [Heading]rr_PortfolioTurnoverHeadingPortfolio Turnover:
Portfolio Turnover [Text Block]rr_PortfolioTurnoverTextBlockThe 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 period, the Fund’s portfolio turnover rate was 93% of the average value of its portfolio.
Portfolio Turnover, Raterr_PortfolioTurnoverRate93.00%
Principal Investment Strategiesjif277751_PrincipalInvestmentStrategiesAbstract 
Strategy [Heading]rr_StrategyHeadingPRINCIPAL 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, and zero-coupon bonds), 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 an underlying asset, such as equity securities, bonds, commodities, currencies, interest rates, or market indices, as substitutes for securities in which the Fund invests. The Fund has invested in and may continue to invest in derivative instruments (by taking long and/or short positions) including, but not limited to, put and call options, particularly on market indices, for hedging purposes (to offset risks associated with an investment, currency exposure or market conditions). The Fund may invest in other types of derivatives and may do so for other purposes including 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. For more information on the Fund’s use of derivatives, refer to the Fund’s shareholder reports and Form N-Q reports, which are filed with the Securities and Exchange Commission.

The Fund’s adviser 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. The Fund’s subadviser 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.

Principal Investment Risksjif277751_PrincipalInvestmentRisksAbstract 
Risk [Heading]rr_RiskHeadingPRINCIPAL 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.

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 their value 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.

Mortgage-Backed Securities Risk. Mortgage-backed securities tend to be more sensitive to changes in interest rates than other types of 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.

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.

Foreign Exposure Risk. The Fund may have exposure to foreign markets, including 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. 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.

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 can be substantially greater than the derivative’s original cost, and can therefore involve 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.

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_RiskLoseMoneyThe biggest risk is that the Fund’s returns and yields will vary, and you could lose money.
Risk Not Insured Depository Institution [Text]rr_RiskNotInsuredDepositoryInstitutionAn 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 INFORMATIONjif277751_FundPastPerformanceAbstract 
Bar Chart and Performance Table [Heading]rr_BarChartAndPerformanceTableHeadingPERFORMANCE INFORMATION
Performance Narrative [Text Block]rr_PerformanceNarrativeTextBlockThe Fund does not have a full calendar year of operations. Performance information for certain periods will be included in the Fund’s first annual and/or semiannual report.
Performance One Year or Less [Text]rr_PerformanceOneYearOrLessThe Fund does not have a full calendar year of operations.
Perkins Value Plus Income Fund | Class D Shares | Class D
 
ANNUAL FUND OPERATING EXPENSESrr_OperatingExpensesAbstract 
Operating Expenses Column [Text]rr_OperatingExpensesColumnNameClass D
Management Feesrr_ManagementFeesOverAssets0.60%
Other Expensesrr_OtherExpensesOverAssets1.14%
Total Annual Fund Operating Expensesrr_ExpensesOverAssets1.74%[35]
Fee Waiverrr_FeeWaiverOrReimbursementOverAssets0.86%[35]
Net Annual Fund Operating Expenses After Fee Waiverrr_NetExpensesOverAssets0.88%[35]
EXAMPLE:rr_ExpenseExampleAbstract 
Expense Example, By Year, Column [Text]rr_ExpenseExampleByYearColumnNameClass D Shares
1 Yearrr_ExpenseExampleYear01177
3 Yearsrr_ExpenseExampleYear03548
5 Yearsrr_ExpenseExampleYear05944
10 Yearsrr_ExpenseExampleYear10 2,052
[1]The future effectiveness of the change is 12/7/2011.
[2]Janus Capital has contractually agreed to waive the Fund's total annual fund operating expenses (excluding any expenses of an underlying fund (acquired fund fees and expenses), 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 - applicable to Class S Shares and Class T Shares; brokerage commissions; interest; dividends; taxes; and extraordinary expenses) to 0.40% until at least November 1, 2012. The contractual waiver may be terminated or modified prior to this date only at the discretion of the Board of Trustees.
[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.
[6]Janus Capital has contractually agreed to waive the Fund's total annual fund operating expenses (excluding any expenses of an underlying fund (acquired fund fees and expenses), administrative services fees payable pursuant to the Transfer Agency Agreement, brokerage commissions, interest, dividends, taxes, and extraordinary expenses) to 0.40% until at least November 1, 2012. The contractual waiver may be terminated or modified prior to this date only at the discretion of the Board of Trustees.
[7]Janus Capital has contractually agreed to waive the Fund's total annual fund operating expenses (excluding any expenses of an underlying fund (acquired fund fees and expenses), 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 - applicable to Class S Shares and Class T Shares; brokerage commissions; interest; dividends; taxes; and extraordinary expenses) to 0.39% until at least November 1, 2012. The contractual waiver may be terminated or modified prior to this date only at the discretion of the Board of Trustees.
[8]Janus Capital has contractually agreed to waive the Fund's total annual fund operating expenses (excluding any expenses of an underlying fund (acquired fund fees and expenses), administrative services fees payable pursuant to the Transfer Agency Agreement, brokerage commissions, interest, dividends, taxes, and extraordinary expenses) to 0.39% until at least November 1, 2012. The contractual waiver may be terminated or modified prior to this date only at the discretion of the Board of Trustees.
[9]Janus Capital has contractually agreed to waive the Fund's total annual fund operating expenses (excluding any expenses of an underlying fund (acquired fund fees and expenses), 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 - applicable to Class S Shares and Class T Shares; brokerage commissions; interest; dividends; taxes; and extraordinary expenses) to 0.45% until at least November 1, 2012. The contractual waiver may be terminated or modified prior to this date only at the discretion of the Board of Trustees.
[10]Janus Capital has contractually agreed to waive the Fund's total annual fund operating expenses (excluding any expenses of an underlying fund (acquired fund fees and expenses), administrative services fees payable pursuant to the Transfer Agency Agreement, brokerage commissions, interest, dividends, taxes, and extraordinary expenses) to 0.45% until at least November 1, 2012. The contractual waiver may be terminated or modified prior to this date only at the discretion of the Board of Trustees.
[11]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 to waive a portion of the Fund's management fee in an amount equal to the management fee paid to Janus Capital by 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.
[12]Since the Fund is new, Other Expenses are based on the estimated expenses that the Fund expects to incur in its initial fiscal period.
[13]Janus Capital has contractually agreed to waive the Fund's total annual fund operating expenses, which include the 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 - applicable to Class S Shares and Class T Shares; brokerage commissions; interest; dividends; taxes; and extraordinary expenses including, but not limited to, acquired fund fees and expenses) to 1.00% until at least November 1, 2012. 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 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 if the Fund's expense ratio, including recovered expenses, falls below the expense limit.
[14]Janus Capital has contractually agreed to waive the Fund's total annual fund operating expenses, which include the expenses of the subsidiary shown above (excluding administrative services fees payable pursuant to the Transfer Agency Agreement, brokerage commissions, interest, dividends, taxes, and extraordinary expenses including, but not limited to, acquired fund fees and expenses) to 1.00% until at least November 1, 2012. 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 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 if the Fund's expense ratio, including recovered expenses, falls below the expense limit.
[15]Janus Capital has contractually agreed to waive the Fund's total annual fund operating expenses (excluding the distribution and shareholder servicing fees - applicable to Class A Shares, Class C Shares, Class S Shares, and Class R Shares; administrative services fees payable pursuant to the Transfer Agency Agreement - applicable to Class S Shares, Class R Shares, and Class T Shares; brokerage commissions; interest; dividends; taxes; and extraordinary expenses including, but not limited to, acquired fund fees and expenses) to 0.55% until at least November 1, 2012. The contractual waiver may be terminated or modified prior to this date only at the discretion of the Board of Trustees.
[16]Janus Capital has contractually agreed to waive the Fund's total annual fund operating expenses (excluding administrative services fees payable pursuant to the Transfer Agency Agreement, brokerage commissions, interest, dividends, taxes, and extraordinary expenses including, but not limited to, acquired fund fees and expenses) to 0.55% until at least November 1, 2012. The contractual waiver may be terminated or modified prior to this date only at the discretion of the Board of Trustees.
[17]Janus Capital has contractually agreed to waive 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 - applicable to Class S Shares and Class T Shares; brokerage commissions; interest; dividends; taxes; and extraordinary expenses including, but not limited to, acquired fund fees and expenses) to 0.75% until at least November 1, 2012. 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 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 if the Fund's expense ratio, including recovered expenses, falls below the expense limit.
[18]Janus Capital has contractually agreed to waive the Fund's total annual fund operating expenses (excluding administrative services fees payable pursuant to the Transfer Agency Agreement, brokerage commissions, interest, dividends, taxes, and extraordinary expenses including, but not limited to, acquired fund fees and expenses) to 0.75% until at least November 1, 2012. 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 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 if the Fund's expense ratio, including recovered expenses, falls below the expense limit.
[19]Janus Capital has contractually agreed to waive the Fund's total annual fund operating expenses (excluding the distribution and shareholder servicing fees - applicable to Class A Shares, Class C Shares, Class S Shares, and Class R Shares; administrative services fees payable pursuant to the Transfer Agency Agreement - applicable to Class S Shares, Class R Shares, and Class T Shares; brokerage commissions; interest; dividends; taxes; and extraordinary expenses including, but not limited to, acquired fund fees and expenses) to 0.78% until at least November 1, 2012. The contractual waiver may be terminated or modified prior to this date only at the discretion of the Board of Trustees.
[20]Janus Capital has contractually agreed to waive the Fund's total annual fund operating expenses (excluding administrative services fees payable pursuant to the Transfer Agency Agreement, brokerage commissions, interest, dividends, taxes, and extraordinary expenses including, but not limited to, acquired fund fees and expenses) to 0.78% until at least November 1, 2012. The contractual waiver may be terminated or modified prior to this date only at the discretion of the Board of Trustees.
[21]Janus Capital has contractually agreed to waive 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 - applicable to Class S Shares and Class T Shares; brokerage commissions; interest; dividends; taxes; and extraordinary expenses including, but not limited to, acquired fund fees and expenses) to 0.55% until at least November 1, 2012. The contractual waiver may be terminated or modified prior to this date only at the discretion of the Board of Trustees.
[22]Janus Capital has contractually agreed to waive 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 - applicable to Class S Shares and Class T Shares; brokerage commissions; interest; dividends; taxes; and extraordinary expenses including, but not limited to, acquired fund fees and expenses) to 1.00% until at least November 1, 2012. The contractual waiver may be terminated or modified prior to this date only at the discretion of the Board of Trustees.
[23]Janus Capital has contractually agreed to waive 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 - applicable to Class S Shares and Class T Shares; brokerage commissions; interest; dividends; taxes; and extraordinary expenses including, but not limited to, acquired fund fees and expenses) to 0.89% until at least November 1, 2012. The contractual waiver may be terminated or modified prior to this date only at the discretion of the Board of Trustees.
[24]Janus Capital has contractually agreed to waive 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, and extraordinary expenses including, but not limited to, acquired fund fees and expenses) to 0.89% until at least November 1, 2012. The contractual waiver may be terminated or modified prior to this date only at the discretion of the Board of Trustees.
[25]Janus Capital has contractually agreed to waive 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 - applicable to Class S Shares and Class T Shares; brokerage commissions; interest; dividends; taxes; and extraordinary expenses including, but not limited to, acquired fund fees and expenses) to 0.90% until at least November 1, 2012. The contractual waiver may be terminated or modified prior to this date only at the discretion of the Board of Trustees.
[26]Janus Capital has contractually agreed to waive 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 - applicable to Class S Shares and Class T Shares; brokerage commissions; interest; dividends; taxes; and extraordinary expenses including, but not limited to, acquired fund fees and expenses) to 0.75% until at least November 1, 2012. The contractual waiver may be terminated or modified prior to this date only at the discretion of the Board of Trustees.
[27]Janus Capital has contractually agreed to waive 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 - applicable to Class S Shares and Class T Shares; brokerage commissions; interest; dividends; taxes; and extraordinary expenses including, but not limited to, acquired fund fees and expenses) to 1.00% until at least November 1, 2012. The contractual waiver may be terminated or modified prior to this date only at the discretion of the Board of Trustees.
[28]Janus Capital has contractually agreed to waive 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, and extraordinary expenses including, but not limited to, acquired fund fees and expenses) to 1.00% until at least November 1, 2012. The contractual waiver may be terminated or modified prior to this date only at the discretion of the Board of Trustees.
[29]Janus Capital has contractually agreed to waive 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, Class S Shares, and Class R Shares; administrative services fees payable pursuant to the Transfer Agency Agreement - applicable to Class S Shares, Class R Shares, and Class T Shares; brokerage commissions; interest; dividends; taxes; and extraordinary expenses including, but not limited to, acquired fund fees and expenses) to 0.86% until at least November 1, 2012. The contractual waiver may be terminated or modified prior to this date only at the discretion of the Board of Trustees.
[30]Janus Capital has contractually agreed to waive 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, and extraordinary expenses including, but not limited to, acquired fund fees and expenses) to 0.86% until at least November 1, 2012. The contractual waiver may be terminated or modified prior to this date only at the discretion of the Board of Trustees.
[31]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.
[32]Janus Capital has contractually agreed to waive 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, Class S Shares, and Class R Shares; administrative services fees payable pursuant to the Transfer Agency Agreement - applicable to Class S Shares, Class R Shares, and Class T Shares; brokerage commissions; interest; dividends; taxes; and extraordinary expenses including, but not limited to, acquired fund fees and expenses) to 0.96% until at least November 1, 2012. The contractual waiver may be terminated or modified prior to this date only at the discretion of the Board of Trustees.
[33]Janus Capital has contractually agreed to waive 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, and extraordinary expenses including, but not limited to, acquired fund fees and expenses) to 0.96% until at least November 1, 2012. The contractual waiver may be terminated or modified prior to this date only at the discretion of the Board of Trustees.
[34]Janus Capital has contractually agreed to waive 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 - applicable to Class S Shares and Class T Shares; brokerage commissions; interest; dividends; taxes; and extraordinary expenses including, but not limited to, acquired fund fees and expenses) to 0.76% until at least November 1, 2012. 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, Janus Capital may recover from the Fund fees and expenses previously waived or reimbursed if the Fund's expense ratio, including recovered expenses, falls below the expense limit.
[35]Janus Capital has contractually agreed to waive the Fund's total annual fund operating expenses (excluding administrative services fees payable pursuant to the Transfer Agency Agreement, brokerage commissions, interest, dividends, taxes, and extraordinary expenses including, but not limited to, acquired fund fees and expenses) to 0.76% until at least November 1, 2012. 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, Janus Capital may recover from the Fund fees and expenses previously waived or reimbursed if the Fund's expense ratio, including recovered expenses, falls below the expense limit.