Label	Element	Value
Risk Return Abstract	rr_RiskReturnAbstract
Prospectus Date	rr_ProspectusDate	Oct. 28, 2021
Class A C S I N R T Shares | Janus Henderson High-Yield Fund
Risk Return Abstract	rr_RiskReturnAbstract
Risk/Return [Heading]	rr_RiskReturnHeading	<span style="color:#000000;font-family:Times New Roman;font-size:15.20pt;font-weight:bold;margin-left:0.57%;">Janus Henderson High-Yield Fund</span>
Objective [Heading]	rr_ObjectiveHeading	<span style="color:#FFFFFF;font-family:Times New Roman;font-size:10.45pt;font-weight:bold;padding-left:0.0%;text-transform:uppercase;">Investment Objectives</span>
Objective, Primary [Text Block]	rr_ObjectivePrimaryTextBlock	Janus Henderson High-Yield Fund seeks to obtain high current income.
Objective, Secondary [Text Block]	rr_ObjectiveSecondaryTextBlock	Capital appreciation is a secondary investment objective when consistent with its primary investment objective.
Expense [Heading]	rr_ExpenseHeading	<span style="color:#FFFFFF;font-family:Times New Roman;font-size:10.45pt;font-weight:bold;padding-left:0.0%;text-transform:uppercase;">Fees and Expenses of the Fund</span>
Expense Narrative [Text Block]	rr_ExpenseNarrativeTextBlock	This table describes the fees and expenses that you may pay if you buy and hold Shares of the Fund. Each share class has different expenses, but represents an investment in the same Fund.For Class A Shares, you may qualify for sales charge discounts if you and your family invest, or agree to invest in the future, at least $50,000 in the Fund or in other Janus Henderson 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 103 of the Fund’s Prospectus and in the “Purchases” section on page 83 of the Fund’s Statement of Additional Information. In addition, please see Appendix A – Intermediary Sales Charge Waivers and Discounts. You may also incur brokerage commissions charged by your broker or financial intermediary when buying Class I Shares or Class N Shares of the Fund that are not reflected in the table or in the example below.
Shareholder Fees Caption [Text]	rr_ShareholderFeesCaption	SHAREHOLDER FEES (fees paid directly from your investment)
Operating Expenses Caption [Text]	rr_OperatingExpensesCaption	ANNUAL FUND OPERATING EXPENSES (expenses that you pay each year as a percentage of the value of your investment)
Fee Waiver or Reimbursement over Assets, Date of Termination	rr_FeeWaiverOrReimbursementOverAssetsDateOfTermination	<span style="font-family:Times New Roman;font-size:7.60pt;">Janus Capital has contractually agreed to waive its investment advisory fee and/or reimburse operating expenses to the extent that the Fund’s total annual fund operating expenses (excluding the fees payable pursuant to a Rule 12b-1 plan, shareholder servicing fees, such as transfer agency fees (including out-of-pocket costs), administrative services fees and any networking/omnibus fees payable by any share class; brokerage commissions; interest; dividends; taxes; acquired fund fees and expenses; and extraordinary expenses) exceed 0.63% for at least a one-year period commencing on October 28, 2021. The contractual waiver may be terminated or modified prior to this date only at the discretion of the Board of Trustees.</span>
Portfolio Turnover [Heading]	rr_PortfolioTurnoverHeading	<span style="font-family:Times New Roman;font-size:9.50pt;font-weight:bold;margin-left:0.00%;">Portfolio Turnover:</span>
Portfolio Turnover [Text Block]	rr_PortfolioTurnoverTextBlock	The Fund pays transaction costs, such as commissions, when it buys and sells securities (or “turns over” its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when Fund shares are held in a taxable account. These costs, which are not reflected in annual fund operating expenses or in the Example, affect the Fund’s performance. During the most recent fiscal year, the Fund’s portfolio turnover rate was 120% of the average value of its portfolio.
Portfolio Turnover, Rate	rr_PortfolioTurnoverRate	120.00%
Expense Breakpoint Discounts [Text]	rr_ExpenseBreakpointDiscounts	<span style="font-family:Times New Roman;font-size:9.50pt;">For Class A Shares, you may qualify for sales charge </span><span style="font-family:Times New Roman;font-size:9.50pt;">discounts if you and your family invest, or agree to invest in the future, at least </span><span style="font-family:Times New Roman;font-size:9.50pt;">$50,000</span><span style="font-family:Times New Roman;font-size:9.50pt;"> in the Fund or in other Janus Henderson 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 103 of the Fund’s Prospectus and in the “Purchases” section on page 83 of the Fund’s Statement of Additional Information. In addition, please see Appendix A – Intermediary Sales Charge Waivers and Discounts. You may also incur brokerage commissions charged by your broker or financial intermediary when buying Class I Shares or Class N Shares of the Fund that are not reflected in the table or in the example below.</span>
Expense Breakpoint, Minimum Investment Required [Amount]	rr_ExpenseBreakpointMinimumInvestmentRequiredAmount	$ 50,000
Expense Example [Heading]	rr_ExpenseExampleHeading	<span style="color:#000000;font-family:Times New Roman;font-size:9.50pt;font-weight:bold;margin-left:0.57%;">EXAMPLE:</span>
Expense Example by Year [Heading]	rr_ExpenseExampleByYearHeading	<span style="font-family:Times New Roman;font-size:9.50pt;">The Example assumes that you invest $10,000 in the </span><span style="font-family:Times New Roman;font-size:9.50pt;">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. Class C Shares automatically convert to Class A Shares after eight years. The Example for Class C Shares for the ten-year period </span><span style="font-family:Times New Roman;font-size:9.50pt;margin-left:0.57%;">reflects the conversion to Class</span><span style="font-family:Times New Roman;font-size:9.50pt;"> A Shares. Although your actual costs may be higher or lower, based on these assumptions your costs would be:</span>
Expense Example Narrative [Text Block]	rr_ExpenseExampleNarrativeTextBlock	The following Example is based on expenses without waivers. The Example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds.
Expense Example by, Year, Caption [Text]	rr_ExpenseExampleByYearCaption	If Shares are redeemed
Expense Example, No Redemption, By Year, Caption [Text]	rr_ExpenseExampleNoRedemptionByYearCaption	If Shares are not redeemed
Strategy [Heading]	rr_StrategyHeading	<span style="color:#FFFFFF;font-family:Times New Roman;font-size:10.45pt;font-weight:bold;padding-left:0.0%;text-transform:uppercase;">Principal investment strategies</span>
Strategy Narrative [Text Block]	rr_StrategyNarrativeTextBlock	The Fund pursues its investment objectives by investing, under normal circumstances, at least 80% of its net assets (plus any borrowings for investment purposes) in high-yield/high-risk securities rated below investment grade (also known as “junk” bonds). Securities rated below investment grade may include their unrated equivalents or other high-yielding securities the portfolio managers believe offer attractive risk/return characteristics. The Fund may at times invest all of its assets in such securities. The Fund may also invest in commercial loans, money market instruments, and foreign debt securities. The Fund may also invest in floating rate obligations, such as collateralized loan obligations, floating rate senior secured syndicated bank loans, floating rate unsecured loans, and other floating rate bonds, loans and notes. Due to the nature of the securities in which the Fund invests, it may have relatively high portfolio turnover compared to other funds.Additionally, the Fund may invest its assets in derivatives, which are instruments that have a value derived from, or directly linked to, an underlying asset, such as equity securities, fixed-income securities, commodities, currencies, interest rates, or market indices. The Fund’s exposure to derivatives will vary. For purposes of meeting its 80% investment policy, the Fund may include derivatives that have characteristics similar to the securities in which the Fund may directly invest. In particular, the Fund may invest in swaps, including index credit default swaps, to increase or decrease the Fund’s exposure to a particular market.In addition to considering economic factors such as the effect of interest rates on the Fund’s investments, the portfolio managers apply a “bottom up” approach in choosing investments. This means that the portfolio managers look at income-producing securities one at a time to determine if a security is an attractive investment opportunity and if it is consistent with the Fund’s investment policies. The portfolio managers additionally consider the expected risk-adjusted return on a particular investment and the Fund’s overall risk allocations and volatility.The Fund may lend portfolio securities on a short-term or long-term basis, in an amount equal to up to one-third of its total assets as determined at the time of the loan origination.
Risk [Heading]	rr_RiskHeading	<span style="color:#FFFFFF;font-family:Times New Roman;font-size:10.45pt;font-weight:bold;padding-left:0.0%;text-transform:uppercase;">Principal investment risks</span>
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. The principal risks and special considerations associated with investing in the Fund are set forth below.High-Yield/High-Risk Bond Risk. The Fund may invest without limit in higher-yielding/higher-risk bonds. High-yield/high-risk bonds are considered speculative and 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. High-yield/high-risk bonds are bonds rated below investment grade by the primary rating agencies such as Standard & Poor’s Ratings Services, Fitch, Inc., and Moody’s Investors Service, Inc. or are unrated bonds of similar quality. The value of lower quality bonds generally is more dependent on credit risk than investment grade bonds. Issuers of high-yield/high-risk bonds may not be as strong financially as those issuing bonds with higher credit ratings and are more vulnerable to real or perceived economic changes, political changes, or adverse developments specific to the issuer. In addition, the junk bond market can experience sudden and sharp price swings.Fixed-Income Securities Risk. The Fund invests in a variety of fixed-income securities. A fundamental risk of fixed-income securities is interest rate risk, which is the risk that prices of bonds and other fixed-income securities will increase as interest rates fall and decrease as interest rates rise. The Fund may be subject to a greater risk of rising interest rates due to the current period of historically low rates. How specific fixed-income securities may react to changes in interest rates will depend on the specific characteristics of each security. For example, while securities with longer maturities and durations tend to offer higher yields, they also tend to be more sensitive to changes in prevailing interest rates and are therefore more volatile than shorter-term securities and are subject to greater market fluctuations as a result of changes in interest rates.Fixed-income securities are also subject to credit risk, prepayment risk, extension risk, valuation risk, and liquidity risk.•Credit risk is the risk that the credit strength of an issuer of a fixed-income security will weaken and/or that the issuer will be unable to make timely principal and interest payments and that the security may go into default.•Prepayment risk is the risk that, during periods of falling interest rates, certain debt obligations may be paid off quicker than originally anticipated, which may cause the Fund to reinvest its assets in securities with lower yields, resulting in a decline in the Fund’s income or return potential.•Extension risk is the risk that, during periods of rising interest rates, certain debt obligations may be paid off substantially slower than originally anticipated, and the value of those securities may fall, resulting in a decline in the Fund’s income and potentially in the value of the Fund’s investments.•Valuation risk is the risk that one or more of the fixed-income securities in which the Fund invests are priced differently than the value realized upon such security’s sale. In times of market instability, valuation may be more difficult.•Liquidity risk is the risk that fixed-income securities may be difficult or impossible to sell at the time that the portfolio managers would like or at the price the portfolio managers believe the security is currently worth.Liquidity Risk . The Fund may invest in securities or instruments that do not trade actively or in large volumes, and may make investments that are less liquid than other investments. Also, the Fund may make investments that may become less liquid in response to market developments or adverse investor perceptions. Investments that are illiquid or that trade in lower volumes may be more difficult to value. When there is no willing buyer and investments cannot be readily sold at the desired time or price, the Fund may have to accept a lower price or may not be able to sell the security or instrument at all. Investments in foreign securities, particularly those of issuers located in emerging market countries, tend to have greater exposure to liquidity risk than domestic securities. In unusual market conditions, even normally liquid securities may be affected by a degree of liquidity risk (i.e., if the number and capacity of traditional market participants is reduced). An inability to sell one or more portfolio positions can adversely affect the Fund’s value or prevent the Fund from being able to take advantage of other investment opportunities.Loan Risk. The Fund may invest in a variety of loans. Bank loans are obligations of companies or other entities sometimes entered into in connection with recapitalizations, acquisitions, and refinancings. The Fund’s investments in bank loans are generally acquired as a participation interest in, or assignment of, loans originated by a lender or other financial institution. These investments may include institutionally-traded floating and fixed-rate debt securities. The bank loans underlying these securities often involve borrowers with low credit ratings whose financial conditions are troubled or uncertain, including companies that are highly leveraged. Loans are subject to credit risk, interest rate risk, and liquidity risk.Floating Rate Obligations Risk. The Fund may invest in floating rate obligations with interest rates that reset regularly, maintaining a fixed spread over a stated reference rate. The interest rates on floating rate obligations typically reset quarterly, although rates on some obligations may adjust at other intervals. Unexpected changes in the interest rates on floating rate obligations could result in lower income to the Fund. In addition, the secondary market on which floating rate obligations are traded may be less liquid than the market for investment grade securities or other types of income-producing securities, which may have an adverse impact on their market price. There is also a potential that there is no active market to trade floating rate obligations, that there may be restrictions on their transfer, or that the issuer may default. As a result, the Fund may be unable to sell floating rate obligations at the desired time or may be able to sell only at a price less than fair market value.Restricted Securities Risk. Securities that have limitations on their resale are referred to as “restricted securities.” Investments in restricted securities, including securities issued under Regulation S and Rule 144A, could have the effect of decreasing the Fund’s liquidity profile or preventing the Fund from disposing of them promptly at advantageous prices. Restricted securities may be less liquid than other investments because such securities may not always be readily sold in broad public markets and may have no active trading market. As a result, they may be difficult to value because market quotations may not be readily available.Foreign Exposure Risk.  The Fund may have exposure to foreign markets as a result of its investments in foreign securities, including investments in emerging markets, which can be more volatile than the U.S. markets. As a result, its returns and net asset value may be affected by fluctuations in currency exchange rates or political or economic conditions in a particular country. In some foreign markets, there may not be protection against failure by other parties to complete transactions. It may not be possible for the Fund to repatriate capital, dividends, interest, and other income from a particular country or governmental entity. In addition, a market swing in one or more countries or regions where the Fund has invested a significant amount of its assets may have a greater effect on the Fund’s performance than it would in a more geographically diversified portfolio. To the extent the Fund invests in foreign debt securities, such investments are sensitive to changes in interest rates. Additionally, investments in securities of foreign governments involve the risk that a foreign government may not be willing or able to pay interest or repay principal when due. Some of the risks of investing directly in foreign securities may be reduced when the Fund invests indirectly in such securities through various other investment vehicles including derivatives, but such investments also involve other risks. The Fund’s investments in emerging market countries, if any, may involve risks greater than, or in addition to, the risks of investing in more developed countries.Portfolio Turnover Risk. Increased portfolio turnover may result in higher costs, which may have a negative effect on the Fund’s performance. In addition, higher portfolio turnover may result in the acceleration of capital gains and the recognition of greater levels of short-term capital gains, which are taxed at ordinary federal income tax rates when distributed to shareholders.Derivatives Risk.  Derivatives can be volatile and involve risks in addition to the risks of the underlying referenced securities or asset. Gains or losses from a derivative investment can be substantially greater than the derivative’s original cost, and can therefore involve leverage. Leverage may cause the Fund to be more volatile than if it had not used leverage. Derivatives can be less liquid than other types of investments and entail the risk that the counterparty will default on its payment obligations.LIBOR Replacement Risk.  The Fund may invest in certain debt securities, derivatives, or other financial instruments that utilize the London Inter-Bank Offered Rate (“LIBOR”) as a reference rate for various rate calculations. The U.K. Financial Conduct Authority has announced that it intends to stop compelling or inducing banks to submit rates for many LIBOR settings after December 31, 2021, and for certain other commonly-used U.S. dollar LIBOR settings after June 30, 2023. The elimination of LIBOR or other reference rates and the transition process away from LIBOR could adversely impact (i) volatility and liquidity in markets that are tied to those reference rates, (ii) the market for, or value of, specific securities or payments linked to those reference rates, (iii) the availability or terms of borrowing or refinancing, or (iv) the effectiveness of hedging strategies. For these and other reasons, the elimination of LIBOR or changes to other interest rates may adversely affect the Fund’s performance and/or net asset value. Alternatives to LIBOR are established or in development in most major currencies including the Secured Overnight Financing Rate (“SOFR”) that is intended to replace the U.S. dollar LIBOR.The effect of the discontinuation of LIBOR or other reference rates on the Fund will vary depending on, among other things (i) existing fallback or termination provisions in individual contracts and (ii) whether, how, and when industry participants develop and adopt new reference rates and fallbacks for both legacy and new products and instruments. Accordingly, it is difficult to predict the full impact of the transition away from LIBOR or other reference rates on the Fund until new reference rates and fallbacks for both legacy and new products, instruments and contracts are commercially accepted.Securities Lending Risk.  The Fund may seek to earn additional income through lending its securities to certain qualified broker-dealers and institutions. There is the risk that when portfolio securities are lent, the securities may not be returned on a timely basis, and the Fund may experience delays and costs in recovering the security or gaining access to the collateral provided to the Fund to collateralize the loan. If the Fund is unable to recover a security on loan, the Fund may use the collateral to purchase replacement securities in the market. There is a risk that the value of the collateral could decrease below the cost of the replacement security by the time the replacement investment is made, resulting in a loss to the Fund.Management Risk.   The Fund is an actively managed investment portfolio and is therefore subject to the risk that the investment strategies employed for the Fund may fail to produce the intended results. The Fund may underperform its benchmark index or other mutual funds with similar investment objectives.An investment in the Fund is not a bank deposit and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency.
Risk Lose Money [Text]	rr_RiskLoseMoney	<span style="font-family:Times New Roman;font-size:9.50pt;margin-left:0.00%;">Although the Fund may be less volatile than funds that invest most of their assets in common stocks, the Fund’s returns and </span><span style="font-family:Times New Roman;font-size:9.50pt;">yields will vary, and you could lose money.</span>
Risk Not Insured Depository Institution [Text]	rr_RiskNotInsuredDepositoryInstitution	<span style="color:#000000;font-family:Times New Roman;font-size:9.50pt;font-style:italic;margin-left:0.00%;">An investment in the Fund is not a bank deposit and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any </span><span style="color:#000000;font-family:Times New Roman;font-size:9.50pt;font-style:italic;">other government agency.</span>
Bar Chart and Performance Table [Heading]	rr_BarChartAndPerformanceTableHeading	<span style="color:#FFFFFF;font-family:Times New Roman;font-size:10.45pt;font-weight:bold;padding-left:0.0%;text-transform:uppercase;">Performance information</span>
Performance Narrative [Text Block]	rr_PerformanceNarrativeTextBlock	The following information provides some indication of the risks of investing in the Fund by showing how the Fund’s performance has varied over time. Class T Shares (formerly named Class J Shares, the initial share class) of the Fund commenced operations with the Fund’s inception. Class A Shares, Class C Shares, Class S Shares, Class I Shares, and Class R Shares of the Fund commenced operations on July 6, 2009. Class N Shares of the Fund commenced operations on May 31, 2012.•The performance shown for Class T Shares is calculated using the fees and expenses of Class T Shares in effect during the periods shown, net of any applicable fee and expense limitations or waivers.•The performance shown for Class A Shares, Class C Shares, Class S Shares, and Class R Shares for periods prior to July 6, 2009, reflects the performance of the Fund’s former Class J Shares, calculated using the fees and expenses of each respective share class, without the effect of any fee and expense limitations or waivers.•The performance shown for Class I Shares for periods prior to July 6, 2009, reflects the performance of the Fund’s former Class J Shares, calculated using the fees and expenses of Class J Shares, net of any applicable fee and expense limitations or waivers.•The performance shown for Class N Shares for periods prior to May 31, 2012, reflects the performance of the Fund’s Class T Shares, calculated using the fees and expenses of Class T Shares, net of any applicable fee and expense limitations or waivers.If Class A Shares, Class C Shares, Class S Shares, Class I Shares, and Class R Shares of the Fund had been available during periods prior to July 6, 2009, or Class N Shares of the Fund had been available during periods prior to May 31, 2012, the performance shown for each respective share class may have been different. The performance shown for the periods following the Fund’s commencement of Class A Shares, Class C Shares, Class S Shares, Class I Shares, Class N Shares, and Class R Shares reflects the fees and expenses of each respective share class, net of any applicable fee and expense limitations or waivers.The bar chart depicts the change in performance from year to year during the periods indicated. The bar chart figures do not include any applicable sales charges that an investor may pay when they buy or sell Class A Shares or Class C Shares of the Fund. If sales charges were included, the returns would be lower.The table compares the Fund’s average annual returns for the periods indicated to a broad-based securities market index. 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 janushenderson.com/performanceor by calling 1-877-335-2687.
Performance Information Illustrates Variability of Returns [Text]	rr_PerformanceInformationIllustratesVariabilityOfReturns	<span style="color:#000000;font-family:Times New Roman;font-size:9.50pt;margin-left:0.00%;">The bar chart depicts the change in performance from year to year during the periods indicated. </span><span style="color:#000000;font-family:Times New Roman;font-size:9.50pt;">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.</span><span style="color:#000000;font-family:Times New Roman;font-size:9.50pt;">The table compares the Fund’s average annual returns for </span><span style="color:#000000;font-family:Times New Roman;font-size:9.50pt;">the periods indicated to a broad-based securities market index. All figures assume reinvestment of dividends and distributions.</span>
Performance Additional Market Index [Text]	rr_PerformanceAdditionalMarketIndex	<span style="color:#000000;font-family:Times New Roman;font-size:9.50pt;">The table compares the Fund’s average annual returns for </span><span style="color:#000000;font-family:Times New Roman;font-size:9.50pt;">the periods indicated to a broad-based securities market index. All figures assume reinvestment of dividends and distributions.</span>
Performance Availability Phone [Text]	rr_PerformanceAvailabilityPhone	<span style="color:#000000;font-family:Times New Roman;font-size:9.50pt;font-style:italic;">1-877-335-2687</span>
Performance Availability Website Address [Text]	rr_PerformanceAvailabilityWebSiteAddress	<span style="color:#000000;font-family:Times New Roman;font-size:9.50pt;font-style:italic;"> janushenderson.com/performance</span>
Performance Past Does Not Indicate Future [Text]	rr_PerformancePastDoesNotIndicateFuture	<span style="color:#000000;font-family:Times New Roman;font-size:9.50pt;font-style:italic;margin-left:0.57%;">The Fund’s past performance (before and after taxes) does not necessarily indicate how it will perform in the future.</span>
Bar Chart [Heading]	rr_BarChartHeading	Annual Total Returns for Class T Shares (calendar year-end)
Bar Chart Does Not Reflect Sales Loads [Text]	rr_BarChartDoesNotReflectSalesLoads	<span style="color:#000000;font-family:Times New Roman;font-size:9.50pt;">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.</span>
Bar Chart Closing [Text Block]	rr_BarChartClosingTextBlock	Best Quarter:2nd Quarter 20209.84%Worst Quarter:1st Quarter 2020– 14.51%
Year to Date Return, Label	rr_YearToDateReturnLabel	<span style="font-family:Times New Roman;font-size:9.50pt;margin-left:0.57%;">The Fund’s year-to-date return as of the calendar quarter ended </span><span style="font-family:Times New Roman;font-size:9.50pt;">September 30, 2021 was 4.89%.</span>
Performance Table Heading	rr_PerformanceTableHeading	Average Annual Total Returns (periods ended 12/31/20)
Performance Table Does Reflect Sales Loads	rr_PerformanceTableDoesReflectSalesLoads	<span style="color:#000000;font-family:Times New Roman;font-size:7.60pt;">The one year return is calculated to include the contingent deferred sales charge.</span>
Performance Table Uses Highest Federal Rate	rr_PerformanceTableUsesHighestFederalRate	<span style="color:#000000;font-family:Times New Roman;font-size:9.50pt;"> 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. </span>
Performance Table Not Relevant to Tax Deferred	rr_PerformanceTableNotRelevantToTaxDeferred	<span style="color:#000000;font-family:Times New Roman;font-size:9.50pt;">Actual after-tax returns depend on your individual tax situation and may differ </span><span style="color:#000000;font-family:Times New Roman;font-size:9.50pt;">from those shown in the preceding table. The after-tax return information shown above does not apply to Fund shares held through a tax-advantaged account, such as a 401(k) plan or an IRA.</span>
Performance Table One Class of after Tax Shown [Text]	rr_PerformanceTableOneClassOfAfterTaxShown	<span style="color:#000000;font-family:Times New Roman;font-size:9.50pt;margin-left:0.00%;">After-tax returns are only shown for Class T Shares of the Fund. After-tax returns for the other classes of Shares will vary </span><span style="color:#000000;font-family:Times New Roman;font-size:9.50pt;">from those shown for Class T Shares due to varying sales charges (as applicable), fees, and expenses among the classes.</span>
Performance Table Explanation after Tax Higher	rr_PerformanceTableExplanationAfterTaxHigher	<span style="color:#000000;font-family:Times New Roman;font-size:7.60pt;">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.</span>
Performance Table Narrative	rr_PerformanceTableNarrativeTextBlock	The Fund’s primary benchmark index is the Bloomberg U.S. Corporate High-Yield Bond Index. The index is described below.•The Bloomberg U.S. Corporate High-Yield Bond Index is composed of fixed-rate, publicly issued, non-investment grade debt.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-advantaged account, such as a 401(k) plan or an IRA.After-tax returns are only shown for Class T Shares of the Fund. After-tax returns for the other classes of Shares will vary from those shown for Class T Shares due to varying sales charges (as applicable), fees, and expenses among the classes.
Performance Table Closing [Text Block]	rr_PerformanceTableClosingTextBlock	Updated performance information is available at janushenderson.com/performanceor by calling 1-877-335-2687.
Class A C S I N R T Shares | Janus Henderson High-Yield Fund | Class A
Risk Return Abstract	rr_RiskReturnAbstract
Maximum Sales Charge (load) Imposed on Purchases (as a percentage of offering price)	rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice	4.75%
Maximum Deferred Sales Charge (load) (as a percentage of the lower of original purchase price or redemption proceeds)	rr_MaximumDeferredSalesChargeOverOther	none
Management Fees	rr_ManagementFeesOverAssets	0.58%
Distribution/Service (12b-1) Fees	rr_DistributionAndService12b1FeesOverAssets	0.25%
Other Expenses	rr_OtherExpensesOverAssets	0.14%
Total Annual Fund Operating Expenses	rr_ExpensesOverAssets	0.97%
Fee Waiver	rr_FeeWaiverOrReimbursementOverAssets	none	[1]
Total Annual Fund Operating Expenses After Fee Waiver	rr_NetExpensesOverAssets	0.97%	[1]
1 Year	rr_ExpenseExampleYear01	$ 569
3 Years	rr_ExpenseExampleYear03	769
5 Years	rr_ExpenseExampleYear05	986
10 Years	rr_ExpenseExampleYear10	1,608
1 Year	rr_ExpenseExampleNoRedemptionYear01	569
3 Years	rr_ExpenseExampleNoRedemptionYear03	769
5 Years	rr_ExpenseExampleNoRedemptionYear05	986
10 Years	rr_ExpenseExampleNoRedemptionYear10	$ 1,608
Class A C S I N R T Shares | Janus Henderson High-Yield Fund | Class C
Risk Return Abstract	rr_RiskReturnAbstract
Maximum Sales Charge (load) Imposed on Purchases (as a percentage of offering price)	rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice	none
Maximum Deferred Sales Charge (load) (as a percentage of the lower of original purchase price or redemption proceeds)	rr_MaximumDeferredSalesChargeOverOther	1.00%
Management Fees	rr_ManagementFeesOverAssets	0.58%
Distribution/Service (12b-1) Fees	rr_DistributionAndService12b1FeesOverAssets	1.00%
Other Expenses	rr_OtherExpensesOverAssets	0.15%
Total Annual Fund Operating Expenses	rr_ExpensesOverAssets	1.73%
Fee Waiver	rr_FeeWaiverOrReimbursementOverAssets	0.02%	[1]
Total Annual Fund Operating Expenses After Fee Waiver	rr_NetExpensesOverAssets	1.71%	[1]
1 Year	rr_ExpenseExampleYear01	$ 276
3 Years	rr_ExpenseExampleYear03	545
5 Years	rr_ExpenseExampleYear05	939
10 Years	rr_ExpenseExampleYear10	1,840
1 Year	rr_ExpenseExampleNoRedemptionYear01	176
3 Years	rr_ExpenseExampleNoRedemptionYear03	545
5 Years	rr_ExpenseExampleNoRedemptionYear05	939
10 Years	rr_ExpenseExampleNoRedemptionYear10	$ 1,840
Class A C S I N R T Shares | Janus Henderson High-Yield Fund | Class S
Risk Return Abstract	rr_RiskReturnAbstract
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
Management Fees	rr_ManagementFeesOverAssets	0.58%
Distribution/Service (12b-1) Fees	rr_DistributionAndService12b1FeesOverAssets	0.25%
Other Expenses	rr_OtherExpensesOverAssets	0.44%
Total Annual Fund Operating Expenses	rr_ExpensesOverAssets	1.27%
Fee Waiver	rr_FeeWaiverOrReimbursementOverAssets	0.14%	[1]
Total Annual Fund Operating Expenses After Fee Waiver	rr_NetExpensesOverAssets	1.13%	[1]
1 Year	rr_ExpenseExampleYear01	$ 129
3 Years	rr_ExpenseExampleYear03	403
5 Years	rr_ExpenseExampleYear05	697
10 Years	rr_ExpenseExampleYear10	1,534
1 Year	rr_ExpenseExampleNoRedemptionYear01	129
3 Years	rr_ExpenseExampleNoRedemptionYear03	403
5 Years	rr_ExpenseExampleNoRedemptionYear05	697
10 Years	rr_ExpenseExampleNoRedemptionYear10	$ 1,534
Class A C S I N R T Shares | Janus Henderson High-Yield Fund | Class I
Risk Return Abstract	rr_RiskReturnAbstract
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
Management Fees	rr_ManagementFeesOverAssets	0.58%
Distribution/Service (12b-1) Fees	rr_DistributionAndService12b1FeesOverAssets	none
Other Expenses	rr_OtherExpensesOverAssets	0.13%
Total Annual Fund Operating Expenses	rr_ExpensesOverAssets	0.71%
Fee Waiver	rr_FeeWaiverOrReimbursementOverAssets	none	[1]
Total Annual Fund Operating Expenses After Fee Waiver	rr_NetExpensesOverAssets	0.71%	[1]
1 Year	rr_ExpenseExampleYear01	$ 73
3 Years	rr_ExpenseExampleYear03	227
5 Years	rr_ExpenseExampleYear05	395
10 Years	rr_ExpenseExampleYear10	883
1 Year	rr_ExpenseExampleNoRedemptionYear01	73
3 Years	rr_ExpenseExampleNoRedemptionYear03	227
5 Years	rr_ExpenseExampleNoRedemptionYear05	395
10 Years	rr_ExpenseExampleNoRedemptionYear10	$ 883
Class A C S I N R T Shares | Janus Henderson High-Yield Fund | Class N
Risk Return Abstract	rr_RiskReturnAbstract
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
Management Fees	rr_ManagementFeesOverAssets	0.58%
Distribution/Service (12b-1) Fees	rr_DistributionAndService12b1FeesOverAssets	none
Other Expenses	rr_OtherExpensesOverAssets	0.04%
Total Annual Fund Operating Expenses	rr_ExpensesOverAssets	0.62%
Fee Waiver	rr_FeeWaiverOrReimbursementOverAssets	none	[1]
Total Annual Fund Operating Expenses After Fee Waiver	rr_NetExpensesOverAssets	0.62%	[1]
1 Year	rr_ExpenseExampleYear01	$ 63
3 Years	rr_ExpenseExampleYear03	199
5 Years	rr_ExpenseExampleYear05	346
10 Years	rr_ExpenseExampleYear10	774
1 Year	rr_ExpenseExampleNoRedemptionYear01	63
3 Years	rr_ExpenseExampleNoRedemptionYear03	199
5 Years	rr_ExpenseExampleNoRedemptionYear05	346
10 Years	rr_ExpenseExampleNoRedemptionYear10	$ 774
Class A C S I N R T Shares | Janus Henderson High-Yield Fund | Class R
Risk Return Abstract	rr_RiskReturnAbstract
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
Management Fees	rr_ManagementFeesOverAssets	0.58%
Distribution/Service (12b-1) Fees	rr_DistributionAndService12b1FeesOverAssets	0.50%
Other Expenses	rr_OtherExpensesOverAssets	0.37%
Total Annual Fund Operating Expenses	rr_ExpensesOverAssets	1.45%
Fee Waiver	rr_FeeWaiverOrReimbursementOverAssets	0.07%	[1]
Total Annual Fund Operating Expenses After Fee Waiver	rr_NetExpensesOverAssets	1.38%	[1]
1 Year	rr_ExpenseExampleYear01	$ 148
3 Years	rr_ExpenseExampleYear03	459
5 Years	rr_ExpenseExampleYear05	792
10 Years	rr_ExpenseExampleYear10	1,735
1 Year	rr_ExpenseExampleNoRedemptionYear01	148
3 Years	rr_ExpenseExampleNoRedemptionYear03	459
5 Years	rr_ExpenseExampleNoRedemptionYear05	792
10 Years	rr_ExpenseExampleNoRedemptionYear10	$ 1,735
Class A C S I N R T Shares | Janus Henderson High-Yield Fund | Class T
Risk Return Abstract	rr_RiskReturnAbstract
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
Management Fees	rr_ManagementFeesOverAssets	0.58%
Distribution/Service (12b-1) Fees	rr_DistributionAndService12b1FeesOverAssets	none
Other Expenses	rr_OtherExpensesOverAssets	0.29%
Total Annual Fund Operating Expenses	rr_ExpensesOverAssets	0.87%
Fee Waiver	rr_FeeWaiverOrReimbursementOverAssets	none	[1]
Total Annual Fund Operating Expenses After Fee Waiver	rr_NetExpensesOverAssets	0.87%	[1]
1 Year	rr_ExpenseExampleYear01	$ 89
3 Years	rr_ExpenseExampleYear03	278
5 Years	rr_ExpenseExampleYear05	482
10 Years	rr_ExpenseExampleYear10	1,073
1 Year	rr_ExpenseExampleNoRedemptionYear01	89
3 Years	rr_ExpenseExampleNoRedemptionYear03	278
5 Years	rr_ExpenseExampleNoRedemptionYear05	482
10 Years	rr_ExpenseExampleNoRedemptionYear10	$ 1,073
2011	rr_AnnualReturn2011	3.20%
2012	rr_AnnualReturn2012	14.30%
2013	rr_AnnualReturn2013	7.31%
2014	rr_AnnualReturn2014	0.69%
2015	rr_AnnualReturn2015	(1.40%)
2016	rr_AnnualReturn2016	12.82%
2017	rr_AnnualReturn2017	6.09%
2018	rr_AnnualReturn2018	(3.06%)
2019	rr_AnnualReturn2019	15.34%
2020	rr_AnnualReturn2020	5.49%
Bar Chart, Year to Date Return, Date	rr_BarChartYearToDateReturnDate	Sep. 30, 2021
Bar Chart, Year to Date Return	rr_BarChartYearToDateReturn	4.89%
Highest Quarterly Return, Label	rr_HighestQuarterlyReturnLabel	Best Quarter
Highest Quarterly Return, Date	rr_BarChartHighestQuarterlyReturnDate	Jun. 30, 2020
Highest Quarterly Return	rr_BarChartHighestQuarterlyReturn	9.84%
Lowest Quarterly Return, Label	rr_LowestQuarterlyReturnLabel	Worst Quarter
Lowest Quarterly Return, Date	rr_BarChartLowestQuarterlyReturnDate	Mar. 31, 2020
Lowest Quarterly Return	rr_BarChartLowestQuarterlyReturn	(14.51%)
Class A C S I N R T Shares | Janus Henderson High-Yield Fund | Return Before Taxes | Class A
Risk Return Abstract	rr_RiskReturnAbstract
1 Year	rr_AverageAnnualReturnYear01	0.29%	[2]
5 Years	rr_AverageAnnualReturnYear05	5.92%	[2]
10 Years	rr_AverageAnnualReturnYear10	5.25%	[2]
Since Inception	rr_AverageAnnualReturnSinceInception	6.95%	[2]
Inception Date	rr_AverageAnnualReturnInceptionDate	Dec. 29, 1995	[2]
Class A C S I N R T Shares | Janus Henderson High-Yield Fund | Return Before Taxes | Class C
Risk Return Abstract	rr_RiskReturnAbstract
1 Year	rr_AverageAnnualReturnYear01	3.59%	[3]
5 Years	rr_AverageAnnualReturnYear05	6.27%	[3]
10 Years	rr_AverageAnnualReturnYear10	5.03%	[3]
Since Inception	rr_AverageAnnualReturnSinceInception	6.41%	[3]
Inception Date	rr_AverageAnnualReturnInceptionDate	Dec. 29, 1995	[3]
Class A C S I N R T Shares | Janus Henderson High-Yield Fund | Return Before Taxes | Class S
Risk Return Abstract	rr_RiskReturnAbstract
1 Year	rr_AverageAnnualReturnYear01	5.16%
5 Years	rr_AverageAnnualReturnYear05	6.82%
10 Years	rr_AverageAnnualReturnYear10	5.60%
Since Inception	rr_AverageAnnualReturnSinceInception	6.96%
Inception Date	rr_AverageAnnualReturnInceptionDate	Dec. 29, 1995
Class A C S I N R T Shares | Janus Henderson High-Yield Fund | Return Before Taxes | Class I
Risk Return Abstract	rr_RiskReturnAbstract
1 Year	rr_AverageAnnualReturnYear01	5.64%
5 Years	rr_AverageAnnualReturnYear05	7.31%
10 Years	rr_AverageAnnualReturnYear10	6.06%
Since Inception	rr_AverageAnnualReturnSinceInception	7.32%
Inception Date	rr_AverageAnnualReturnInceptionDate	Dec. 29, 1995
Class A C S I N R T Shares | Janus Henderson High-Yield Fund | Return Before Taxes | Class N
Risk Return Abstract	rr_RiskReturnAbstract
1 Year	rr_AverageAnnualReturnYear01	5.62%
5 Years	rr_AverageAnnualReturnYear05	7.37%
10 Years	rr_AverageAnnualReturnYear10	6.11%
Since Inception	rr_AverageAnnualReturnSinceInception	7.33%
Inception Date	rr_AverageAnnualReturnInceptionDate	Dec. 29, 1995
Class A C S I N R T Shares | Janus Henderson High-Yield Fund | Return Before Taxes | Class R
Risk Return Abstract	rr_RiskReturnAbstract
1 Year	rr_AverageAnnualReturnYear01	4.89%
5 Years	rr_AverageAnnualReturnYear05	6.55%
10 Years	rr_AverageAnnualReturnYear10	5.34%
Since Inception	rr_AverageAnnualReturnSinceInception	6.69%
Inception Date	rr_AverageAnnualReturnInceptionDate	Dec. 29, 1995
Class A C S I N R T Shares | Janus Henderson High-Yield Fund | Return Before Taxes | Class T
Risk Return Abstract	rr_RiskReturnAbstract
1 Year	rr_AverageAnnualReturnYear01	5.49%
5 Years	rr_AverageAnnualReturnYear05	7.14%
10 Years	rr_AverageAnnualReturnYear10	5.90%
Since Inception	rr_AverageAnnualReturnSinceInception	7.24%
Inception Date	rr_AverageAnnualReturnInceptionDate	Dec. 29, 1995
Class A C S I N R T Shares | Janus Henderson High-Yield Fund | Return After Taxes on Distributions | Class T
Risk Return Abstract	rr_RiskReturnAbstract
1 Year	rr_AverageAnnualReturnYear01	3.23%
5 Years	rr_AverageAnnualReturnYear05	4.69%
10 Years	rr_AverageAnnualReturnYear10	3.25%
Since Inception	rr_AverageAnnualReturnSinceInception	4.19%
Inception Date	rr_AverageAnnualReturnInceptionDate	Dec. 29, 1995
Class A C S I N R T Shares | Janus Henderson High-Yield Fund | Return After Taxes on Distributions and Sale of Fund Shares | Class T
Risk Return Abstract	rr_RiskReturnAbstract
1 Year	rr_AverageAnnualReturnYear01	3.15%	[4]
5 Years	rr_AverageAnnualReturnYear05	4.38%	[4]
10 Years	rr_AverageAnnualReturnYear10	3.38%	[4]
Since Inception	rr_AverageAnnualReturnSinceInception	4.28%	[4]
Inception Date	rr_AverageAnnualReturnInceptionDate	Dec. 29, 1995	[4]
Class A C S I N R T Shares | Janus Henderson High-Yield Fund | Bloomberg U.S. Corporate High-Yield Bond Index (reflects no deduction for expenses, fees, or taxes) | Class A
Risk Return Abstract	rr_RiskReturnAbstract
1 Year	rr_AverageAnnualReturnYear01	7.11%
5 Years	rr_AverageAnnualReturnYear05	8.59%
10 Years	rr_AverageAnnualReturnYear10	6.80%
Since Inception	rr_AverageAnnualReturnSinceInception	7.11%
Class A C S I N R T Shares | Janus Henderson High-Yield Fund | Bloomberg U.S. Corporate High-Yield Bond Index (reflects no deduction for expenses, fees, or taxes) | Class C
Risk Return Abstract	rr_RiskReturnAbstract
1 Year	rr_AverageAnnualReturnYear01	7.11%
5 Years	rr_AverageAnnualReturnYear05	8.59%
10 Years	rr_AverageAnnualReturnYear10	6.80%
Since Inception	rr_AverageAnnualReturnSinceInception	7.11%
Class A C S I N R T Shares | Janus Henderson High-Yield Fund | Bloomberg U.S. Corporate High-Yield Bond Index (reflects no deduction for expenses, fees, or taxes) | Class S
Risk Return Abstract	rr_RiskReturnAbstract
1 Year	rr_AverageAnnualReturnYear01	7.11%
5 Years	rr_AverageAnnualReturnYear05	8.59%
10 Years	rr_AverageAnnualReturnYear10	6.80%
Since Inception	rr_AverageAnnualReturnSinceInception	7.11%
Class A C S I N R T Shares | Janus Henderson High-Yield Fund | Bloomberg U.S. Corporate High-Yield Bond Index (reflects no deduction for expenses, fees, or taxes) | Class I
Risk Return Abstract	rr_RiskReturnAbstract
1 Year	rr_AverageAnnualReturnYear01	7.11%
5 Years	rr_AverageAnnualReturnYear05	8.59%
10 Years	rr_AverageAnnualReturnYear10	6.80%
Since Inception	rr_AverageAnnualReturnSinceInception	7.11%
Class A C S I N R T Shares | Janus Henderson High-Yield Fund | Bloomberg U.S. Corporate High-Yield Bond Index (reflects no deduction for expenses, fees, or taxes) | Class N
Risk Return Abstract	rr_RiskReturnAbstract
1 Year	rr_AverageAnnualReturnYear01	7.11%
5 Years	rr_AverageAnnualReturnYear05	8.59%
10 Years	rr_AverageAnnualReturnYear10	6.80%
Since Inception	rr_AverageAnnualReturnSinceInception	7.11%
Class A C S I N R T Shares | Janus Henderson High-Yield Fund | Bloomberg U.S. Corporate High-Yield Bond Index (reflects no deduction for expenses, fees, or taxes) | Class R
Risk Return Abstract	rr_RiskReturnAbstract
1 Year	rr_AverageAnnualReturnYear01	7.11%
5 Years	rr_AverageAnnualReturnYear05	8.59%
10 Years	rr_AverageAnnualReturnYear10	6.80%
Since Inception	rr_AverageAnnualReturnSinceInception	7.11%
Class A C S I N R T Shares | Janus Henderson High-Yield Fund | Bloomberg U.S. Corporate High-Yield Bond Index (reflects no deduction for expenses, fees, or taxes) | Class T
Risk Return Abstract	rr_RiskReturnAbstract
1 Year	rr_AverageAnnualReturnYear01	7.11%
5 Years	rr_AverageAnnualReturnYear05	8.59%
10 Years	rr_AverageAnnualReturnYear10	6.80%
Since Inception	rr_AverageAnnualReturnSinceInception	7.11%

[1] Janus Capital has contractually agreed to waive its investment advisory fee and/or reimburse operating expenses to the extent that the Fund’s total annual fund operating expenses (excluding the fees payable pursuant to a Rule 12b-1 plan, shareholder servicing fees, such as transfer agency fees (including out-of-pocket costs), administrative services fees and any networking/omnibus fees payable by any share class; brokerage commissions; interest; dividends; taxes; acquired fund fees and expenses; and extraordinary expenses) exceed 0.63% for at least a one-year period commencing on October 28, 2021. The contractual waiver may be terminated or modified prior to this date only at the discretion of the Board of Trustees.

[2] Calculated assuming maximum permitted sales loads.

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

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