Label	Element	Value
Risk Return Abstract	rr_RiskReturnAbstract
Registrant Name	dei_EntityRegistrantName	JANUS INVESTMENT FUND
Class I N Shares | Janus Henderson U.S. Dividend Income Fund
Risk Return Abstract	rr_RiskReturnAbstract
Risk/Return [Heading]	rr_RiskReturnHeading	<span style="font-family:Times New Roman;font-size:15.20pt;font-weight:bold;margin-left:3pt;">Janus Henderson U.S. Dividend Income Fund</span>
Objective [Heading]	rr_ObjectiveHeading	<span style="color:#FFFFFF;font-family:Times New Roman;font-size:10.45pt;font-weight:bold;margin-left:0.0pt;text-transform:uppercase;">Investment Objective</span>
Objective, Primary [Text Block]	rr_ObjectivePrimaryTextBlock	Janus Henderson U.S. Dividend Income Fund seeks to provide current income and aims to provide a growing stream of income per share over time.The Fund’s secondary objective is to seek to provide long-term capital appreciation.
Objective, Secondary [Text Block]	rr_ObjectiveSecondaryTextBlock	The Fund's secondary objective is to seek to provide long-term capital appreciation.
Expense [Heading]	rr_ExpenseHeading	<span style="color:#FFFFFF;font-family:Times New Roman;font-size:10.45pt;font-weight:bold;margin-left:0.0pt;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, hold, and sell Shares of the Fund. Each share class has different expenses, but represents an investment in the same Fund. 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 102 of the Fund’s Prospectus and in the “Purchases” section on page 77 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.
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;">The Adviser 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 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 0.75% for at least a one-year period commencing on January 26, 2024. The contractual waiver may be terminated or modified prior to this date only at the discretion of the Board of Trustees. For a period beginning with the Fund’s commencement of operations (December 20, 2022) and expiring on the third anniversary of the commencement of operations, or until the Fund’s assets meet the first breakpoint in the investment advisory fee schedule (0.60% of the first $2 billion of the average daily closing net asset value of the Fund), whichever occurs first, the Adviser 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 or the expense limit in effect at the time the fees and expenses subject to recoupment were waived. There is no guarantee that the Fund’s assets will reach this asset level.</span>
Portfolio Turnover [Heading]	rr_PortfolioTurnoverHeading	<span style="font-family:Times New Roman;font-size:9.50pt;font-weight:bold;">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 period December 20, 2022 through September 30, 2023, the Fund’s portfolio turnover rate was 85% of the average value of its portfolio.
Portfolio Turnover, Rate	rr_PortfolioTurnoverRate	85.00%
Expense Example [Heading]	rr_ExpenseExampleHeading	<span style="font-family:Times New Roman;font-size:9.50pt;font-weight:bold;">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 Fund for the time periods indicated, reinvest all dividends and </span><span style="font-family:Times New Roman;font-size:9.50pt;">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 are equal to the Total Annual Fund Operating Expenses After Fee Waiver and/or Expense Reimbursement for the first year and the Total Annual Fund Operating Expenses thereafter. 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 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
Strategy [Heading]	rr_StrategyHeading	<span style="color:#FFFFFF;font-family:Times New Roman;font-size:10.45pt;font-weight:bold;margin-left:0.0pt;text-transform:uppercase;">Principal investment strategies</span>
Strategy Narrative [Text Block]	rr_StrategyNarrativeTextBlock	The Fund pursues its investment objective by investing, under normal circumstances, at least 80% of its net assets (plus any borrowings for investment purposes) in a portfolio of dividend-paying equity securities of U.S. companies. An issuer is deemed to be economically tied to the United States if one or more of the following tests are met: (i) the issuer is organized in, or its primary business office or principal trading market of its equity is located in, the United States; (ii) a majority of the issuer’s revenues are derived from the United States; or (iii) a majority of the issuer’s assets are located in the United States.The Fund generally invests in a core group of approximately 40-50 equity securities, including common stocks. The Fund will invest primarily in larger, well-established companies.Portfolio management primarily seeks to identify high-quality companies with the ability to grow revenue and cash flows and produce growing dividend streams through disparate economic environments. Such companies, in portfolio management’s view, have the ability to participate in market gains while offering resilient dividends. Security selection will be based upon an analysis of a broad range of metrics, including returns on invested capital, balance sheet strength, and revenue growth potential.The Fund will generally consider selling a security when, in portfolio management’s opinion, there is a risk of significant deterioration in the company’s fundamentals, or there is a change in business strategy or issuer-specific business outlook that affects the original investment case. The Fund will also consider selling a security if, in portfolio management’s opinion, it has become overvalued or if a superior investment opportunity arises.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;margin-left:0.0pt;text-transform:uppercase;">Principal investment risks</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;margin-left:0.0pt;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.The bar chart depicts the change in performance from year to year during the period indicated. 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 atjanushenderson.com/performance or by calling 1-877-335-2687.
Performance Information Illustrates Variability of Returns [Text]	rr_PerformanceInformationIllustratesVariabilityOfReturns	<span style="font-family:Times New Roman;font-size:9.50pt;">The bar chart depicts the change in performance from year to year during the period indicated. </span><span style="font-family:Times New Roman;font-size:9.50pt;">The table compares the </span><span style="font-family:Times New Roman;font-size:9.50pt;">Fund’s average annual returns for 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="font-family:Times New Roman;font-size:9.50pt;">The table compares the </span><span style="font-family:Times New Roman;font-size:9.50pt;">Fund’s average annual returns for 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="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="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="font-family:Times New Roman;font-size:9.50pt;font-style:italic;">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 I Shares (calendar year-end)
Bar Chart Closing [Text Block]	rr_BarChartClosingTextBlock	Best Quarter:4th Quarter 20238.23%Worst Quarter:3rd Quarter 2023– 2.77%
Performance Table Heading	rr_PerformanceTableHeading	Average Annual Total Returns (periods ended 12/31/23)
Performance Table Uses Highest Federal Rate	rr_PerformanceTableUsesHighestFederalRate	<span style="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="font-family:Times New Roman;font-size:9.50pt;">Actual after-tax returns depend on your individual tax situation and may differ from those </span><span style="font-family:Times New Roman;font-size:9.50pt;">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="font-family:Times New Roman;font-size:9.50pt;">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.</span>
Performance Table Narrative	rr_PerformanceTableNarrativeTextBlock	The Fund’s primary benchmark index is the Russell 1000 Value Index. The index is described below.•The Russell 1000 Value Index measures the performance of those Russell 1000 companies with lower price-to-book ratios and lower forecasted growth values.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 I Shares of the Fund. After-tax returns for the other classes of Shares will vary from those shown for Class I Shares due to varying sales charges (as applicable), fees, and expenses among the classes.
Performance Table Closing [Text Block]	rr_PerformanceTableClosingTextBlock	Updated performance information is available atjanushenderson.com/performance or by calling 1-877-335-2687.
Class I N Shares | Janus Henderson U.S. Dividend Income Fund | Risk Lose Money [Member]
Risk Return Abstract	rr_RiskReturnAbstract
Risk [Text Block]	rr_RiskTextBlock	The biggest risk is that the Fund’s returns will vary, and you could lose money.
Class I N Shares | Janus Henderson U.S. Dividend Income Fund | Risk Not Insured Depository Institution [Member]
Risk Return Abstract	rr_RiskReturnAbstract
Risk [Text Block]	rr_RiskTextBlock	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.
Class I N Shares | Janus Henderson U.S. Dividend Income Fund | Market Risk [Member]
Risk Return Abstract	rr_RiskReturnAbstract
Risk [Text Block]	rr_RiskTextBlock	Market Risk. The value of the Fund’s portfolio may decrease due to short-term market movements and over more prolonged market downturns. As a result, the Fund’s net asset value may fluctuate and it may be more difficult to value or sell the Fund’s holdings. Market risk may affect a single issuer, industry, economic sector, or the market as a whole. Market risk may be magnified if certain social, political, economic, and other conditions and events (such as terrorism, conflicts, including related sanctions, social unrest, natural disasters, epidemics and pandemics, including COVID-19) adversely interrupt the global economy and financial markets. 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.
Class I N Shares | Janus Henderson U.S. Dividend Income Fund | Dividend-Oriented Stocks Risk [Member]
Risk Return Abstract	rr_RiskReturnAbstract
Risk [Text Block]	rr_RiskTextBlock	Dividend-Oriented Stocks Risk. Companies that have paid regular dividends to shareholders may decrease or eliminate dividend payments in the future. A decrease in dividend payments by an issuer may result in a decrease in the value of the security held by the Fund or the Fund receiving less income.
Class I N Shares | Janus Henderson U.S. Dividend Income Fund | Value Investing Risk [Member]
Risk Return Abstract	rr_RiskReturnAbstract
Risk [Text Block]	rr_RiskTextBlock	Value Investing Risk. Because different types of stocks tend to shift in and out of favor depending on market and economic conditions, “value” stocks may perform differently than other types of stocks and from the market as a whole, and can continue to be undervalued by the market for long periods of time. It is also possible that a value stock will never appreciate to the extent expected by portfolio management.
Class I N Shares | Janus Henderson U.S. Dividend Income Fund | Portfolio Management Risk [Member]
Risk Return Abstract	rr_RiskReturnAbstract
Risk [Text Block]	rr_RiskTextBlock	Portfolio Management Risk. The Fund is an actively managed investment portfolio and is therefore subject to the risk that the investment strategies and research process employed for the Fund may fail to produce the intended results. Accordingly, the Fund may underperform its benchmark index or other mutual funds with similar investment objectives.
Class I N Shares | Janus Henderson U.S. Dividend Income Fund | Issuer Concentration Risk [Member]
Risk Return Abstract	rr_RiskReturnAbstract
Risk [Text Block]	rr_RiskTextBlock	Issuer Concentration Risk. The Fund’s portfolio may be comprised of a relatively small number of issuers in comparison to other funds. As a result, the Fund may be subject to greater risks than a fund that invests in a greater number of issuers. A change in the value of any single investment held by the Fund may affect the overall value of the Fund more than it would affect a fund that holds more investments. In particular, the Fund may be more susceptible to adverse developments affecting any single issuer held by the Fund and may be susceptible to greater losses because of these developments.
Class I N Shares | Janus Henderson U.S. Dividend Income Fund | New Smaller Sized Fund Risk [Member]
Risk Return Abstract	rr_RiskReturnAbstract
Risk [Text Block]	rr_RiskTextBlock	New/Smaller Sized Fund Risk. Because the Fund is relatively new, it has a limited operating history and a small asset base. The Fund’s performance may not represent how the Fund is expected to or may perform in the long term if and when it becomes larger. If the Fund were to fail to attract sufficient assets to achieve or maintain economies of scale, performance may be negatively impacted, and any resulting liquidation could create negative transaction costs for the Fund and tax consequences for investors.
Class I N Shares | Janus Henderson U.S. Dividend Income Fund | Large Shareholder Risk [Member]
Risk Return Abstract	rr_RiskReturnAbstract
Risk [Text Block]	rr_RiskTextBlock	Large Shareholder Risk. To the extent a substantial percentage of the shares of the Fund are held by a small number of shareholders, including “fund of funds” or accounts over which the Adviser has investment discretion, the Fund is subject to the risk that these shareholders will purchase or redeem the Fund’s shares in large amounts rapidly or unexpectedly, including as a result of an asset allocation decision made by the Adviser. These transactions could adversely affect the ability of the Fund to conduct its investment program.
Class I N Shares | Janus Henderson U.S. Dividend Income Fund | Securities Lending Risk [Member]
Risk Return Abstract	rr_RiskReturnAbstract
Risk [Text Block]	rr_RiskTextBlock	Securities Lending Risk. 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.
Class I N Shares | Janus Henderson U.S. Dividend Income Fund | Class I
Risk Return Abstract	rr_RiskReturnAbstract
Management Fees	rr_ManagementFeesOverAssets	0.60%
Other Expenses	rr_OtherExpensesOverAssets	15.84%
Total Annual Fund Operating Expenses	rr_ExpensesOverAssets	16.44%
Fee Waiver and/or Expense Reimbursement	rr_FeeWaiverOrReimbursementOverAssets	15.65%	[1]
Total Annual Fund Operating Expenses After Fee Waiver and/or Expense Reimbursement	rr_NetExpensesOverAssets	0.79%	[1]
1 Year	rr_ExpenseExampleYear01	$ 81
3 Years	rr_ExpenseExampleYear03	3,126
5 Years	rr_ExpenseExampleYear05	5,515
10 Years	rr_ExpenseExampleYear10	$ 9,469
2023	rr_AnnualReturn2023	6.95%
Highest Quarterly Return, Label	rr_HighestQuarterlyReturnLabel	Best Quarter
Highest Quarterly Return, Date	rr_BarChartHighestQuarterlyReturnDate	Dec. 31, 2023
Highest Quarterly Return	rr_BarChartHighestQuarterlyReturn	8.23%
Lowest Quarterly Return, Label	rr_LowestQuarterlyReturnLabel	Worst Quarter
Lowest Quarterly Return, Date	rr_BarChartLowestQuarterlyReturnDate	Sep. 30, 2023
Lowest Quarterly Return	rr_BarChartLowestQuarterlyReturn	(2.77%)
Class I N Shares | Janus Henderson U.S. Dividend Income Fund | Class N
Risk Return Abstract	rr_RiskReturnAbstract
Management Fees	rr_ManagementFeesOverAssets	0.60%
Other Expenses	rr_OtherExpensesOverAssets	1.40%
Total Annual Fund Operating Expenses	rr_ExpensesOverAssets	2.00%
Fee Waiver and/or Expense Reimbursement	rr_FeeWaiverOrReimbursementOverAssets	1.24%	[1]
Total Annual Fund Operating Expenses After Fee Waiver and/or Expense Reimbursement	rr_NetExpensesOverAssets	0.76%	[1]
1 Year	rr_ExpenseExampleYear01	$ 78
3 Years	rr_ExpenseExampleYear03	507
5 Years	rr_ExpenseExampleYear05	963
10 Years	rr_ExpenseExampleYear10	$ 2,227
Class I N Shares | Janus Henderson U.S. Dividend Income Fund | Return Before Taxes | Class I
Risk Return Abstract	rr_RiskReturnAbstract
1 Year	rr_AverageAnnualReturnYear01	6.95%
Since Inception	rr_AverageAnnualReturnSinceInception	7.78%
Inception Date	rr_AverageAnnualReturnInceptionDate	Dec. 20, 2022
Class I N Shares | Janus Henderson U.S. Dividend Income Fund | Return Before Taxes | Class N
Risk Return Abstract	rr_RiskReturnAbstract
1 Year	rr_AverageAnnualReturnYear01	6.96%
Since Inception	rr_AverageAnnualReturnSinceInception	7.78%
Inception Date	rr_AverageAnnualReturnInceptionDate	Dec. 20, 2022
Class I N Shares | Janus Henderson U.S. Dividend Income Fund | Return After Taxes on Distributions | Class I
Risk Return Abstract	rr_RiskReturnAbstract
1 Year	rr_AverageAnnualReturnYear01	6.49%
Since Inception	rr_AverageAnnualReturnSinceInception	7.33%
Inception Date	rr_AverageAnnualReturnInceptionDate	Dec. 20, 2022
Class I N Shares | Janus Henderson U.S. Dividend Income Fund | Return After Taxes on Distributions and Sale of Fund Shares | Class I
Risk Return Abstract	rr_RiskReturnAbstract
1 Year	rr_AverageAnnualReturnYear01	4.37%
Since Inception	rr_AverageAnnualReturnSinceInception	5.88%
Inception Date	rr_AverageAnnualReturnInceptionDate	Dec. 20, 2022
Class I N Shares | Janus Henderson U.S. Dividend Income Fund | Russell 1000® Value Index (reflects no deduction for expenses, fees, or taxes) | Class I
Risk Return Abstract	rr_RiskReturnAbstract
1 Year	rr_AverageAnnualReturnYear01	11.46%
Since Inception	rr_AverageAnnualReturnSinceInception	12.58%
Class I N Shares | Janus Henderson U.S. Dividend Income Fund | Russell 1000® Value Index (reflects no deduction for expenses, fees, or taxes) | Class N
Risk Return Abstract	rr_RiskReturnAbstract
1 Year	rr_AverageAnnualReturnYear01	11.46%
Since Inception	rr_AverageAnnualReturnSinceInception	12.58%

[1] The Adviser 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 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 0.75% for at least a one-year period commencing on January 26, 2024. The contractual waiver may be terminated or modified prior to this date only at the discretion of the Board of Trustees. For a period beginning with the Fund’s commencement of operations (December 20, 2022) and expiring on the third anniversary of the commencement of operations, or until the Fund’s assets meet the first breakpoint in the investment advisory fee schedule (0.60% of the first $2 billion of the average daily closing net asset value of the Fund), whichever occurs first, the Adviser 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 or the expense limit in effect at the time the fees and expenses subject to recoupment were waived. There is no guarantee that the Fund’s assets will reach this asset level.