Label	Element	Value
Risk Return Abstract	rr_RiskReturnAbstract
Registrant Name	dei_EntityRegistrantName	JANUS INVESTMENT FUND
Class A C S I N R T Shares | Janus Henderson Growth and Income 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:3pt;">Janus Henderson Growth and 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 Growth and Income Fund seeks long-term capital growth and current income.
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. 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 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 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.
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;">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 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 0.62% for at least a one-year period commencing on January 26, 2024. This contractual waiver may be terminated or modified 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;">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 22% of the average value of its portfolio.
Portfolio Turnover, Rate	rr_PortfolioTurnoverRate	22.00%
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 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 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.</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;">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 and reinvest all dividends </span><span style="font-family:Times New Roman;font-size:9.50pt;">and distributions. 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. Class C Shares automatically convert to Class A Shares </span><span style="color:#000000;font-family:Times New Roman;font-size:9.50pt;">after eight years. The Example for Class C Shares for the ten-year period reflects the conversion to Class 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 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;margin-left:0.0pt;text-transform:uppercase;">Principal investment strategies</span>
Strategy Narrative [Text Block]	rr_StrategyNarrativeTextBlock	The Fund pursues its investment objective by normally investing in dividend-paying common stocks with strong growth potential.Portfolio management applies a “bottom up” approach in choosing investments. In other words, portfolio management looks at companies one at a time to determine if a company is an attractive investment opportunity and if it is consistent with the Fund’s investment policies. Factors that portfolio management may consider in its fundamental analysis include a company’s returns on capital, balance sheet flexibility, and dividend growth potential. Portfolio management will generally consider selling a security when, among other things, it reaches or exceeds its targeted value, the investment thesis for owning the position has changed, or to rebalance industry or sector weightings.
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. 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 August 4, 2017.•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 August 4, 2017, 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 August 4, 2017, 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 atjanushenderson.com/performance or 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;">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 </span><span style="color:#000000;font-family:Times New Roman;font-size:9.50pt;">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;">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 </span><span style="color:#000000;font-family:Times New Roman;font-size:9.50pt;">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 202017.76%Worst Quarter:1st Quarter 2020– 22.99%
Performance Table Heading	rr_PerformanceTableHeading	Average Annual Total Returns (periods ended 12/31/23)
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;">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.</span>
Performance Table Narrative	rr_PerformanceTableNarrativeTextBlock	The Fund’s primary benchmark index is the S&P 500 Index. The index is described below.•The S&P 500 Index is a commonly recognized, market capitalization-weighted index of 500 widely held equity securities, designed to measure broad U.S. equity performance.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 atjanushenderson.com/performance or by calling 1-877-335-2687.
Class A C S I N R T Shares | Janus Henderson Growth and 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 A C S I N R T Shares | Janus Henderson Growth and 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 A C S I N R T Shares | Janus Henderson Growth and 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 A C S I N R T Shares | Janus Henderson Growth and Income Fund | Growth Securities Risk [Member]
Risk Return Abstract	rr_RiskReturnAbstract
Risk [Text Block]	rr_RiskTextBlock	Growth Securities Risk. Securities of companies perceived to be “growth” companies may be more volatile than other stocks and may involve special risks. If portfolio management’s perception of a company’s growth potential is not realized, the securities purchased may not perform as expected, reducing the Fund’s returns. In addition, because different types of stocks tend to shift in and out of favor depending on market and economic conditions, “growth” stocks may perform differently from other types of securities and the market as a whole.
Class A C S I N R T Shares | Janus Henderson Growth and Income Fund | Industry and Sector Risk [Member]
Risk Return Abstract	rr_RiskReturnAbstract
Risk [Text Block]	rr_RiskTextBlock	Industry and Sector Risk. Although the Fund does not concentrate its investments in specific industries, it may have a significant portion of its assets invested in securities of companies conducting similar business or businesses within the same economic sector. Companies in the same industry or economic sector may be similarly affected by economic or market events, making the Fund more vulnerable to unfavorable developments than funds that invest more broadly. As the Fund’s portfolio becomes more concentrated, the Fund is less able to spread risk and potentially reduce the risk of loss and volatility. In addition, the Fund may be overweight or underweight in certain industries or sectors relative to its benchmark index, which may cause the Fund’s performance to be more or less sensitive to developments affecting those sectors.
Class A C S I N R T Shares | Janus Henderson Growth and 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 A C S I N R T Shares | Janus Henderson Growth and 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 A C S I N R T Shares | Janus Henderson Growth and Income Fund | Class A
Risk Return Abstract	rr_RiskReturnAbstract
Maximum Sales Charge (load) Imposed on Purchases (as a percentage of offering price)	rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice	5.75%
Maximum Deferred Sales Charge (load) (as a percentage of the lower of original purchase price or redemption proceeds)	rr_MaximumDeferredSalesChargeOverOther	none
Management Fees	rr_ManagementFeesOverAssets	0.60%
Distribution/Service (12b-1) Fees	rr_DistributionAndService12b1FeesOverAssets	0.25%
Other Expenses	rr_OtherExpensesOverAssets	0.16%
Total Annual Fund Operating Expenses	rr_ExpensesOverAssets	1.01%
Fee Waiver and/or Expense Reimbursement	rr_FeeWaiverOrReimbursementOverAssets	none	[1]
Total Annual Fund Operating Expenses After Fee Waiver and/or Expense Reimbursement	rr_NetExpensesOverAssets	1.01%	[1]
1 Year	rr_ExpenseExampleYear01	$ 672
3 Years	rr_ExpenseExampleYear03	878
5 Years	rr_ExpenseExampleYear05	1,101
10 Years	rr_ExpenseExampleYear10	1,740
1 Year	rr_ExpenseExampleNoRedemptionYear01	672
3 Years	rr_ExpenseExampleNoRedemptionYear03	878
5 Years	rr_ExpenseExampleNoRedemptionYear05	1,101
10 Years	rr_ExpenseExampleNoRedemptionYear10	$ 1,740
Class A C S I N R T Shares | Janus Henderson Growth and Income 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	0.60%
Distribution/Service (12b-1) Fees	rr_DistributionAndService12b1FeesOverAssets	1.00%
Other Expenses	rr_OtherExpensesOverAssets	0.09%
Total Annual Fund Operating Expenses	rr_ExpensesOverAssets	1.69%
Fee Waiver and/or Expense Reimbursement	rr_FeeWaiverOrReimbursementOverAssets	0.01%	[1]
Total Annual Fund Operating Expenses After Fee Waiver and/or Expense Reimbursement	rr_NetExpensesOverAssets	1.68%	[1]
1 Year	rr_ExpenseExampleYear01	$ 271
3 Years	rr_ExpenseExampleYear03	532
5 Years	rr_ExpenseExampleYear05	917
10 Years	rr_ExpenseExampleYear10	1,816
1 Year	rr_ExpenseExampleNoRedemptionYear01	171
3 Years	rr_ExpenseExampleNoRedemptionYear03	532
5 Years	rr_ExpenseExampleNoRedemptionYear05	917
10 Years	rr_ExpenseExampleNoRedemptionYear10	$ 1,816
Class A C S I N R T Shares | Janus Henderson Growth and Income 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	0.60%
Distribution/Service (12b-1) Fees	rr_DistributionAndService12b1FeesOverAssets	0.25%
Other Expenses	rr_OtherExpensesOverAssets	0.29%
Total Annual Fund Operating Expenses	rr_ExpensesOverAssets	1.14%
Fee Waiver and/or Expense Reimbursement	rr_FeeWaiverOrReimbursementOverAssets	0.02%	[1]
Total Annual Fund Operating Expenses After Fee Waiver and/or Expense Reimbursement	rr_NetExpensesOverAssets	1.12%	[1]
1 Year	rr_ExpenseExampleYear01	$ 114
3 Years	rr_ExpenseExampleYear03	360
5 Years	rr_ExpenseExampleYear05	626
10 Years	rr_ExpenseExampleYear10	1,384
1 Year	rr_ExpenseExampleNoRedemptionYear01	114
3 Years	rr_ExpenseExampleNoRedemptionYear03	360
5 Years	rr_ExpenseExampleNoRedemptionYear05	626
10 Years	rr_ExpenseExampleNoRedemptionYear10	$ 1,384
Class A C S I N R T Shares | Janus Henderson Growth and Income 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	0.60%
Distribution/Service (12b-1) Fees	rr_DistributionAndService12b1FeesOverAssets	none
Other Expenses	rr_OtherExpensesOverAssets	0.10%
Total Annual Fund Operating Expenses	rr_ExpensesOverAssets	0.70%
Fee Waiver and/or Expense Reimbursement	rr_FeeWaiverOrReimbursementOverAssets	none	[1]
Total Annual Fund Operating Expenses After Fee Waiver and/or Expense Reimbursement	rr_NetExpensesOverAssets	0.70%	[1]
1 Year	rr_ExpenseExampleYear01	$ 72
3 Years	rr_ExpenseExampleYear03	224
5 Years	rr_ExpenseExampleYear05	390
10 Years	rr_ExpenseExampleYear10	871
1 Year	rr_ExpenseExampleNoRedemptionYear01	72
3 Years	rr_ExpenseExampleNoRedemptionYear03	224
5 Years	rr_ExpenseExampleNoRedemptionYear05	390
10 Years	rr_ExpenseExampleNoRedemptionYear10	$ 871
Class A C S I N R T Shares | Janus Henderson Growth and Income 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	0.60%
Distribution/Service (12b-1) Fees	rr_DistributionAndService12b1FeesOverAssets	none
Other Expenses	rr_OtherExpensesOverAssets	0.03%
Total Annual Fund Operating Expenses	rr_ExpensesOverAssets	0.63%
Fee Waiver and/or Expense Reimbursement	rr_FeeWaiverOrReimbursementOverAssets	0.01%	[1]
Total Annual Fund Operating Expenses After Fee Waiver and/or Expense Reimbursement	rr_NetExpensesOverAssets	0.62%	[1]
1 Year	rr_ExpenseExampleYear01	$ 63
3 Years	rr_ExpenseExampleYear03	201
5 Years	rr_ExpenseExampleYear05	350
10 Years	rr_ExpenseExampleYear10	785
1 Year	rr_ExpenseExampleNoRedemptionYear01	63
3 Years	rr_ExpenseExampleNoRedemptionYear03	201
5 Years	rr_ExpenseExampleNoRedemptionYear05	350
10 Years	rr_ExpenseExampleNoRedemptionYear10	$ 785
Class A C S I N R T Shares | Janus Henderson Growth and Income 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	0.60%
Distribution/Service (12b-1) Fees	rr_DistributionAndService12b1FeesOverAssets	0.50%
Other Expenses	rr_OtherExpensesOverAssets	0.32%
Total Annual Fund Operating Expenses	rr_ExpensesOverAssets	1.42%
Fee Waiver and/or Expense Reimbursement	rr_FeeWaiverOrReimbursementOverAssets	0.05%	[1]
Total Annual Fund Operating Expenses After Fee Waiver and/or Expense Reimbursement	rr_NetExpensesOverAssets	1.37%	[1]
1 Year	rr_ExpenseExampleYear01	$ 139
3 Years	rr_ExpenseExampleYear03	444
5 Years	rr_ExpenseExampleYear05	772
10 Years	rr_ExpenseExampleYear10	1,698
1 Year	rr_ExpenseExampleNoRedemptionYear01	139
3 Years	rr_ExpenseExampleNoRedemptionYear03	444
5 Years	rr_ExpenseExampleNoRedemptionYear05	772
10 Years	rr_ExpenseExampleNoRedemptionYear10	$ 1,698
Class A C S I N R T Shares | Janus Henderson Growth and Income 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	0.60%
Distribution/Service (12b-1) Fees	rr_DistributionAndService12b1FeesOverAssets	none
Other Expenses	rr_OtherExpensesOverAssets	0.27%
Total Annual Fund Operating Expenses	rr_ExpensesOverAssets	0.87%
Fee Waiver and/or Expense Reimbursement	rr_FeeWaiverOrReimbursementOverAssets	none	[1]
Total Annual Fund Operating Expenses After Fee Waiver and/or Expense Reimbursement	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
2014	rr_AnnualReturn2014	11.10%
2015	rr_AnnualReturn2015	1.38%
2016	rr_AnnualReturn2016	12.83%
2017	rr_AnnualReturn2017	24.78%
2018	rr_AnnualReturn2018	(2.07%)
2019	rr_AnnualReturn2019	26.85%
2020	rr_AnnualReturn2020	10.20%
2021	rr_AnnualReturn2021	28.77%
2022	rr_AnnualReturn2022	(14.28%)
2023	rr_AnnualReturn2023	17.84%
Highest Quarterly Return, Label	rr_HighestQuarterlyReturnLabel	Best Quarter
Highest Quarterly Return, Date	rr_BarChartHighestQuarterlyReturnDate	Jun. 30, 2020
Highest Quarterly Return	rr_BarChartHighestQuarterlyReturn	17.76%
Lowest Quarterly Return, Label	rr_LowestQuarterlyReturnLabel	Worst Quarter
Lowest Quarterly Return, Date	rr_BarChartLowestQuarterlyReturnDate	Mar. 31, 2020
Lowest Quarterly Return	rr_BarChartLowestQuarterlyReturn	(22.99%)
Class A C S I N R T Shares | Janus Henderson Growth and Income Fund | Return Before Taxes | Class A
Risk Return Abstract	rr_RiskReturnAbstract
1 Year	rr_AverageAnnualReturnYear01	10.89%	[2]
5 Years	rr_AverageAnnualReturnYear05	11.21%	[2]
10 Years	rr_AverageAnnualReturnYear10	10.16%	[2]
Since Inception	rr_AverageAnnualReturnSinceInception	10.49%	[2]
Inception Date	rr_AverageAnnualReturnInceptionDate	May 15, 1991	[2]
Class A C S I N R T Shares | Janus Henderson Growth and Income Fund | Return Before Taxes | Class C
Risk Return Abstract	rr_RiskReturnAbstract
1 Year	rr_AverageAnnualReturnYear01	15.93%	[3]
5 Years	rr_AverageAnnualReturnYear05	11.81%	[3]
10 Years	rr_AverageAnnualReturnYear10	10.05%	[3]
Since Inception	rr_AverageAnnualReturnSinceInception	9.93%	[3]
Inception Date	rr_AverageAnnualReturnInceptionDate	May 15, 1991	[3]
Class A C S I N R T Shares | Janus Henderson Growth and Income Fund | Return Before Taxes | Class S
Risk Return Abstract	rr_RiskReturnAbstract
1 Year	rr_AverageAnnualReturnYear01	17.51%
5 Years	rr_AverageAnnualReturnYear05	12.40%
10 Years	rr_AverageAnnualReturnYear10	10.65%
Since Inception	rr_AverageAnnualReturnSinceInception	10.52%
Inception Date	rr_AverageAnnualReturnInceptionDate	May 15, 1991
Class A C S I N R T Shares | Janus Henderson Growth and Income Fund | Return Before Taxes | Class I
Risk Return Abstract	rr_RiskReturnAbstract
1 Year	rr_AverageAnnualReturnYear01	18.02%
5 Years	rr_AverageAnnualReturnYear05	12.87%
10 Years	rr_AverageAnnualReturnYear10	11.11%
Since Inception	rr_AverageAnnualReturnSinceInception	10.85%
Inception Date	rr_AverageAnnualReturnInceptionDate	May 15, 1991
Class A C S I N R T Shares | Janus Henderson Growth and Income Fund | Return Before Taxes | Class N
Risk Return Abstract	rr_RiskReturnAbstract
1 Year	rr_AverageAnnualReturnYear01	18.11%
5 Years	rr_AverageAnnualReturnYear05	12.96%
10 Years	rr_AverageAnnualReturnYear10	11.10%
Since Inception	rr_AverageAnnualReturnSinceInception	10.82%
Inception Date	rr_AverageAnnualReturnInceptionDate	May 15, 1991
Class A C S I N R T Shares | Janus Henderson Growth and Income Fund | Return Before Taxes | Class R
Risk Return Abstract	rr_RiskReturnAbstract
1 Year	rr_AverageAnnualReturnYear01	17.17%
5 Years	rr_AverageAnnualReturnYear05	12.08%
10 Years	rr_AverageAnnualReturnYear10	10.34%
Since Inception	rr_AverageAnnualReturnSinceInception	10.26%
Inception Date	rr_AverageAnnualReturnInceptionDate	May 15, 1991
Class A C S I N R T Shares | Janus Henderson Growth and Income Fund | Return Before Taxes | Class T
Risk Return Abstract	rr_RiskReturnAbstract
1 Year	rr_AverageAnnualReturnYear01	17.84%
5 Years	rr_AverageAnnualReturnYear05	12.70%
10 Years	rr_AverageAnnualReturnYear10	10.94%
Since Inception	rr_AverageAnnualReturnSinceInception	10.77%
Inception Date	rr_AverageAnnualReturnInceptionDate	May 15, 1991
Class A C S I N R T Shares | Janus Henderson Growth and Income Fund | Return After Taxes on Distributions | Class T
Risk Return Abstract	rr_RiskReturnAbstract
1 Year	rr_AverageAnnualReturnYear01	15.74%
5 Years	rr_AverageAnnualReturnYear05	11.25%
10 Years	rr_AverageAnnualReturnYear10	9.39%
Since Inception	rr_AverageAnnualReturnSinceInception	9.60%
Inception Date	rr_AverageAnnualReturnInceptionDate	May 15, 1991
Class A C S I N R T Shares | Janus Henderson Growth and Income Fund | Return After Taxes on Distributions and Sale of Fund Shares | Class T
Risk Return Abstract	rr_RiskReturnAbstract
1 Year	rr_AverageAnnualReturnYear01	11.98%
5 Years	rr_AverageAnnualReturnYear05	10.00%
10 Years	rr_AverageAnnualReturnYear10	8.62%
Since Inception	rr_AverageAnnualReturnSinceInception	9.15%
Inception Date	rr_AverageAnnualReturnInceptionDate	May 15, 1991
Class A C S I N R T Shares | Janus Henderson Growth and Income Fund | S&P 500® Index (reflects no deduction for expenses, fees, or taxes) | Class A
Risk Return Abstract	rr_RiskReturnAbstract
1 Year	rr_AverageAnnualReturnYear01	26.29%
5 Years	rr_AverageAnnualReturnYear05	15.69%
10 Years	rr_AverageAnnualReturnYear10	12.03%
Since Inception	rr_AverageAnnualReturnSinceInception	10.35%
Class A C S I N R T Shares | Janus Henderson Growth and Income Fund | S&P 500® Index (reflects no deduction for expenses, fees, or taxes) | Class C
Risk Return Abstract	rr_RiskReturnAbstract
1 Year	rr_AverageAnnualReturnYear01	26.29%
5 Years	rr_AverageAnnualReturnYear05	15.69%
10 Years	rr_AverageAnnualReturnYear10	12.03%
Since Inception	rr_AverageAnnualReturnSinceInception	10.35%
Class A C S I N R T Shares | Janus Henderson Growth and Income Fund | S&P 500® Index (reflects no deduction for expenses, fees, or taxes) | Class S
Risk Return Abstract	rr_RiskReturnAbstract
1 Year	rr_AverageAnnualReturnYear01	26.29%
5 Years	rr_AverageAnnualReturnYear05	15.69%
10 Years	rr_AverageAnnualReturnYear10	12.03%
Since Inception	rr_AverageAnnualReturnSinceInception	10.35%
Class A C S I N R T Shares | Janus Henderson Growth and Income Fund | S&P 500® Index (reflects no deduction for expenses, fees, or taxes) | Class I
Risk Return Abstract	rr_RiskReturnAbstract
1 Year	rr_AverageAnnualReturnYear01	26.29%
5 Years	rr_AverageAnnualReturnYear05	15.69%
10 Years	rr_AverageAnnualReturnYear10	12.03%
Since Inception	rr_AverageAnnualReturnSinceInception	10.35%
Class A C S I N R T Shares | Janus Henderson Growth and Income Fund | S&P 500® Index (reflects no deduction for expenses, fees, or taxes) | Class N
Risk Return Abstract	rr_RiskReturnAbstract
1 Year	rr_AverageAnnualReturnYear01	26.29%
5 Years	rr_AverageAnnualReturnYear05	15.69%
10 Years	rr_AverageAnnualReturnYear10	12.03%
Since Inception	rr_AverageAnnualReturnSinceInception	10.35%
Class A C S I N R T Shares | Janus Henderson Growth and Income Fund | S&P 500® Index (reflects no deduction for expenses, fees, or taxes) | Class R
Risk Return Abstract	rr_RiskReturnAbstract
1 Year	rr_AverageAnnualReturnYear01	26.29%
5 Years	rr_AverageAnnualReturnYear05	15.69%
10 Years	rr_AverageAnnualReturnYear10	12.03%
Since Inception	rr_AverageAnnualReturnSinceInception	10.35%
Class A C S I N R T Shares | Janus Henderson Growth and Income Fund | S&P 500® Index (reflects no deduction for expenses, fees, or taxes) | Class T
Risk Return Abstract	rr_RiskReturnAbstract
1 Year	rr_AverageAnnualReturnYear01	26.29%
5 Years	rr_AverageAnnualReturnYear05	15.69%
10 Years	rr_AverageAnnualReturnYear10	12.03%
Since Inception	rr_AverageAnnualReturnSinceInception	10.35%

[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 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 0.62% for at least a one-year period commencing on January 26, 2024. This contractual waiver may be terminated or modified 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.