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 Global Sustainable Equity 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 Global Sustainable Equity 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 Global Sustainable Equity Fund seeks long-term growth of capital.
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 128 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,</span><span style="font-family:Times New Roman;font-size:7.60pt;">taxes, acquired fund fees and expenses, and extraordinary expenses) exceed 0.85% for at least a one-year period commencing on January </span><span style="font-family:Times New Roman;font-size:7.60pt;line-height:9.50pt;"> </span><span style="font-family:Times New Roman;font-size:7.60pt;">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 20% of the average value of its portfolio.
Portfolio Turnover, Rate	rr_PortfolioTurnoverRate	20.00%
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 128 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 investing, under normal circumstances, at least 80% of its net assets (plus any borrowings for investment purposes) in equity securities. The Fund will typically invest in companies whose products and services are considered by portfolio management as contributing to positive environmental or social change and sustainable economic development, including those that are strategically aligned with environmental and social megatrends such as climate change, resource constraints, growing populations, and aging populations.The Fund typically invests at least 40% of its net assets in securities of issuers or companies that are economically tied to different countries throughout the world, excluding the United States. An issuer is deemed to be economically tied to a country or countries 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 country; (ii) a majority of the issuer’s revenues are derived from one or more countries; or (iii) a majority of the issuer’s assets are located in one or more countries. The Fund’s investments may be in non-U.S. currency or U.S. dollar-denominated.The Fund generally invests in a core group of 50-70 equity securities, which consist primarily of common stocks, but may also include other types of instruments, such as depositary receipts and warrants. The Fund may also invest in real estate investment trusts (“REITs”). The Fund will invest primarily in larger, well-established companies but may also invest in mid- and small-sized companies. The Fund’s uninvested assets may be held in cash or cash equivalents.In selecting investments, portfolio management employs a “bottom-up” approach that focuses on fundamental research. To identify the universe of investible securities for the Fund, portfolio management first employs positive selection criteria that seeks to identify companies that derive at least 50% of their current or future expected revenues from at least one of ten environmental and social themes. Environmental themes include efficiency, cleaner energy, water management, environmental services, and sustainable transport. Social themes include sustainable property and finance, safety, quality of life, knowledge and technology, and health.Next, portfolio management applies broad-based negative screens, which rely on third-party inputs, to seek to avoid securities of issuers that, in the determination of the Adviser, are significantly engaged in or derive more than de minimis revenue from industries, activities, or assets considered by portfolio management to have a negative impact on society or the environment. A current list of such industries, activities, or assets, which may evolve over time, follows:•alcohol;•animal testing (non-medical);•armaments;•chemicals of concern;•fossil fuel extraction and refining;•fossil fuel power generation;•fur;•gambling;•genetic engineering;•intensive farming;•meat and dairy production;•nuclear power;•pornography;•tobacco; and•United Nations Global Compact and Organization for Economic Co-operation and Development violators.In selecting investments, portfolio management will then consider, among other factors, a company’s growth potential, competitive positioning, operational quality, and strategy. Portfolio management may also consider factors such as a company’s historic and projected return on capital, balance sheets, and financial models. Portfolio management will also consider environmental, social, and governance (“ESG”) factors, which may include climate change, deforestation, biodiversity, human rights, company culture, community relations, board structure and diversity, executive pay, and corporate reporting. Portfolio management seeks to maintain a portfolio of securities that has a carbon footprint and carbon intensity that is at least 20% below the MSCI World Indexsm. At portfolio management’s discretion, the Fund will engage with a company’s management regarding matters that may include shareholder rights, governance and remuneration, climate change, carbon emissions, pollution, biodiversity, human capital, and diversity and inclusion.Portfolio management evaluates and applies ESG and sustainable investment criteria relying on a mix of third-party data and internally-generated analyses based on information that may include web-based research reports from a company or independent sources, as well as corporate engagement. Portfolio management does not apply these ESG factors in managing the Fund’s exposure to cash and cash equivalents.The Fund will generally consider selling a stock if, in portfolio management’s opinion, there has been a regulatory, industry, or position-level change that may impair a company’s revenue growth. The Fund will also consider selling a stock if, in portfolio management’s opinion, the company’s business model no longer meets the sustainable investment criteria employed in managing the Fund.
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 A Shares, Class C Shares, Class S Shares, Class I Shares, Class N Shares, and Class T Shares of the Fund commenced operations with the Fund’s inception. Class R Shares of the Fund commenced operations on January 28, 2021.•The performance shown for Class A Shares, Class C Shares, Class S Shares, Class I Shares, Class N Shares, and Class T Shares is calculated using the fees and expenses of each respective share class, net of any applicable fee and expense limitations or waivers.•The performance shown for Class R Shares for periods prior to January 28, 2021, reflects the performance of the Fund’s Class I Shares, calculated using the fees and expenses of Class R Shares, without the effect of any fee and expense limitations or waivers. If Class R Shares of the Fund had been available during periods prior to January 28, 2021, the performance shown may have been different. The performance shown for the periods following the Fund’s commencement of Class R Shares reflects the fees and expenses of Class R Shares, net of any applicable fee and expense limitations or waivers.The bar chart depicts the change in performance from year to year during the periods indicated. The 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 I 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:4th Quarter 202313.52%Worst Quarter:2nd Quarter 2022– 17.80%
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 from those </span><span style="color:#000000;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="color:#000000;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 MSCI World Index. The index is described below.•The MSCI World Index is designed to measure the equity market performance of developed market countries in North America, Europe, and the Asia/Pacific Region.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 A C S I N R T Shares | Janus Henderson Global Sustainable Equity 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 Global Sustainable Equity 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 Global Sustainable Equity 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 Global Sustainable Equity Fund | Sustainable Investment Risk [Member]
Risk Return Abstract	rr_RiskReturnAbstract
Risk [Text Block]	rr_RiskTextBlock	Sustainable Investment Risk. The Fund follows a sustainable investment approach by investing in companies that relate to certain sustainable development themes and demonstrate adherence to ESG practices. Accordingly, the Fund may have a significant portion of its assets invested in securities of companies conducting similar business or businesses within the same economic sector, which may make the Fund more vulnerable to unfavorable developments in a particular sector than funds that invest more broadly. Additionally, due to its exclusionary criteria, the Fund may not be invested in certain industries or sectors, and therefore may have lower performance than portfolios that do not apply similar criteria. In addition, because sustainable and ESG investing takes into consideration factors beyond traditional financial analysis, the investment opportunities for the Fund may be limited at times. Sustainability and ESG-related information provided by issuers and third parties, upon which portfolio management may rely, continues to develop, and may be incomplete, inaccurate, use different methodologies, or be applied differently across companies and industries. Further, the regulatory landscape for sustainable and ESG investing in the United States is still developing and future rules and regulations may require the Fund to modify or alter its investment process. Similarly, government policies incentivizing companies to engage in sustainable and ESG practices may fall out of favor, which could potentially limit the Fund’s investment universe. There is also a risk that the companies identified through the investment process may fail to adhere to sustainable and/or ESG-related business practices, which may result in the Fund selling a security when it might otherwise be disadvantageous to do so.
Class A C S I N R T Shares | Janus Henderson Global Sustainable Equity 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 emphasizes certain themes and megatrends. As a result, at times, it may have a significant portion of its assets invested in securities of companies conducting similar business or businesses within the same economic sector or that benefit from the same megatrend. Companies in the same industry or economic sector or that benefit from the same megatrend 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.
Class A C S I N R T Shares | Janus Henderson Global Sustainable Equity Fund | Currency Risk [Member]
Risk Return Abstract	rr_RiskReturnAbstract
Risk [Text Block]	rr_RiskTextBlock	Currency Risk. Currency risk is the risk that changes in the exchange rate between currencies will adversely affect the value (in U.S. dollar terms) of an investment. As long as the Fund holds a foreign security, its value will be affected by the value of the local currency relative to the U.S. dollar. When the Fund sells a foreign currency denominated security, its value may be worth less in U.S. dollars even if the security increases in value in its home country. U.S. dollar-denominated securities of foreign issuers may also be affected by currency risk, as the value of these securities may also be affected by changes in the issuer’s local currency.
Class A C S I N R T Shares | Janus Henderson Global Sustainable Equity Fund | Foreign Exposure Risk [Member]
Risk Return Abstract	rr_RiskReturnAbstract
Risk [Text Block]	rr_RiskTextBlock	Foreign Exposure Risk. Foreign markets can be more volatile than the U.S. market. As a result, the Fund’s 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.
Class A C S I N R T Shares | Janus Henderson Global Sustainable Equity 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 portfolio management may not be successful in identifying investment opportunities that are aligned with the sustainable investment approach that the Fund employs. 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 Global Sustainable Equity Fund | Small- and Mid-Sized Companies Risk [Member]
Risk Return Abstract	rr_RiskReturnAbstract
Risk [Text Block]	rr_RiskTextBlock	Small- and Mid-Sized Companies Risk. Investments in securities issued by small- and mid-sized companies, which can include smaller, start-up companies offering emerging products or services, may involve greater risks than are customarily associated with larger, more established companies. For example, small- and mid-sized companies may suffer more significant losses as a result of their narrow product lines, limited operating history, greater exposure to competitive threats, limited financial resources, limited trading markets, and the potential lack of management depth. Securities issued by small- and mid-sized companies tend to be more volatile and somewhat more speculative than securities issued by larger or more established companies and may underperform as compared to the securities of larger or more established companies. These holdings are also subject to wider price fluctuations and tend to be less liquid than stocks of larger or more established companies, which could have a significant adverse effect on the Fund’s returns, especially as market conditions change.
Class A C S I N R T Shares | Janus Henderson Global Sustainable Equity Fund | Liquidity Risk [Member]
Risk Return Abstract	rr_RiskReturnAbstract
Risk [Text Block]	rr_RiskTextBlock	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.
Class A C S I N R T Shares | Janus Henderson Global Sustainable Equity Fund | REIT Risk [Member]
Risk Return Abstract	rr_RiskReturnAbstract
Risk [Text Block]	rr_RiskTextBlock	REIT Risk. REITs are subject to certain risks inherent in the direct ownership of real estate, including without limitation, a possible lack of mortgage funds and associated interest rate risks, overbuilding, property vacancies, increases in property taxes and operating expenses, changes in zoning laws, losses due to environmental damages and changes in neighborhood values and appeal to purchasers. In addition, a REIT could fail to qualify for tax-free pass-through of its income under the Internal Revenue Code of 1986, as amended, or fail to maintain its exemption from registration under the Investment Company Act of 1940, as amended, which could produce adverse economic consequences for the REIT and its investors, including the Fund. Dividends received by the Fund from a REIT generally will not constitute qualified dividend income.
Class A C S I N R T Shares | Janus Henderson Global Sustainable Equity Fund | Smaller Sized Fund Risk [Member]
Risk Return Abstract	rr_RiskReturnAbstract
Risk [Text Block]	rr_RiskTextBlock	Smaller Sized Fund Risk. Because the Fund has a small asset base, large inflows and outflows may have a disproportionate impact, negative or positive, on the Fund’s performance, which may be more volatile than that of a larger fund. If the Fund were to fail to attract sufficient assets to achieve or maintain economies of scale, its performance may be negatively impacted, and any resulting liquidation could create negative transaction costs for the Fund and tax consequences for investors.
Class A C S I N R T Shares | Janus Henderson Global Sustainable Equity Fund | Depositary Receipts Risk [Member]
Risk Return Abstract	rr_RiskReturnAbstract
Risk [Text Block]	rr_RiskTextBlock	Depositary Receipts Risk. Depositary receipts are generally subject to the same sort of risks as direct investments in a foreign country, such as currency risk, market risk, and foreign exposure risk, because their values depend on the performance of a foreign security denominated in its home currency.
Class A C S I N R T Shares | Janus Henderson Global Sustainable Equity Fund | Warrants Risk [Member]
Risk Return Abstract	rr_RiskReturnAbstract
Risk [Text Block]	rr_RiskTextBlock	Warrants Risk. The price, performance and liquidity of warrants to purchase equity securities are typically linked to the underlying stock. These instruments have many characteristics of convertible securities and, similarly, will react to variations in the general market for equity securities.
Class A C S I N R T Shares | Janus Henderson Global Sustainable Equity 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	0.75%
Distribution/Service (12b-1) Fees	rr_DistributionAndService12b1FeesOverAssets	0.25%
Other Expenses	rr_OtherExpensesOverAssets	2.24%
Total Annual Fund Operating Expenses	rr_ExpensesOverAssets	3.24%
Fee Waiver and/or Expense Reimbursement	rr_FeeWaiverOrReimbursementOverAssets	2.03%	[1]
Total Annual Fund Operating Expenses After Fee Waiver and/or Expense Reimbursement	rr_NetExpensesOverAssets	1.21%	[1]
1 Year	rr_ExpenseExampleYear01	$ 691
3 Years	rr_ExpenseExampleYear03	1,336
5 Years	rr_ExpenseExampleYear05	2,004
10 Years	rr_ExpenseExampleYear10	3,780
1 Year	rr_ExpenseExampleNoRedemptionYear01	691
3 Years	rr_ExpenseExampleNoRedemptionYear03	1,336
5 Years	rr_ExpenseExampleNoRedemptionYear05	2,004
10 Years	rr_ExpenseExampleNoRedemptionYear10	$ 3,780
Class A C S I N R T Shares | Janus Henderson Global Sustainable Equity 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	0.75%
Distribution/Service (12b-1) Fees	rr_DistributionAndService12b1FeesOverAssets	1.00%
Other Expenses	rr_OtherExpensesOverAssets	4.42%
Total Annual Fund Operating Expenses	rr_ExpensesOverAssets	6.17%
Fee Waiver and/or Expense Reimbursement	rr_FeeWaiverOrReimbursementOverAssets	4.28%	[1]
Total Annual Fund Operating Expenses After Fee Waiver and/or Expense Reimbursement	rr_NetExpensesOverAssets	1.89%	[1]
1 Year	rr_ExpenseExampleYear01	$ 292
3 Years	rr_ExpenseExampleYear03	1,449
5 Years	rr_ExpenseExampleYear05	2,678
10 Years	rr_ExpenseExampleYear10	5,093
1 Year	rr_ExpenseExampleNoRedemptionYear01	192
3 Years	rr_ExpenseExampleNoRedemptionYear03	1,449
5 Years	rr_ExpenseExampleNoRedemptionYear05	2,678
10 Years	rr_ExpenseExampleNoRedemptionYear10	$ 5,093
Class A C S I N R T Shares | Janus Henderson Global Sustainable Equity 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	0.75%
Distribution/Service (12b-1) Fees	rr_DistributionAndService12b1FeesOverAssets	0.25%
Other Expenses	rr_OtherExpensesOverAssets	6.07%
Total Annual Fund Operating Expenses	rr_ExpensesOverAssets	7.07%
Fee Waiver and/or Expense Reimbursement	rr_FeeWaiverOrReimbursementOverAssets	5.71%	[1]
Total Annual Fund Operating Expenses After Fee Waiver and/or Expense Reimbursement	rr_NetExpensesOverAssets	1.36%	[1]
1 Year	rr_ExpenseExampleYear01	$ 138
3 Years	rr_ExpenseExampleYear03	1,574
5 Years	rr_ExpenseExampleYear05	2,950
10 Years	rr_ExpenseExampleYear10	6,150
1 Year	rr_ExpenseExampleNoRedemptionYear01	138
3 Years	rr_ExpenseExampleNoRedemptionYear03	1,574
5 Years	rr_ExpenseExampleNoRedemptionYear05	2,950
10 Years	rr_ExpenseExampleNoRedemptionYear10	$ 6,150
Class A C S I N R T Shares | Janus Henderson Global Sustainable Equity 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	0.75%
Distribution/Service (12b-1) Fees	rr_DistributionAndService12b1FeesOverAssets	none
Other Expenses	rr_OtherExpensesOverAssets	1.23%
Total Annual Fund Operating Expenses	rr_ExpensesOverAssets	1.98%
Fee Waiver and/or Expense Reimbursement	rr_FeeWaiverOrReimbursementOverAssets	0.97%	[1]
Total Annual Fund Operating Expenses After Fee Waiver and/or Expense Reimbursement	rr_NetExpensesOverAssets	1.01%	[1]
1 Year	rr_ExpenseExampleYear01	$ 103
3 Years	rr_ExpenseExampleYear03	527
5 Years	rr_ExpenseExampleYear05	978
10 Years	rr_ExpenseExampleYear10	2,228
1 Year	rr_ExpenseExampleNoRedemptionYear01	103
3 Years	rr_ExpenseExampleNoRedemptionYear03	527
5 Years	rr_ExpenseExampleNoRedemptionYear05	978
10 Years	rr_ExpenseExampleNoRedemptionYear10	$ 2,228
2021	rr_AnnualReturn2021	16.21%
2022	rr_AnnualReturn2022	(24.23%)
2023	rr_AnnualReturn2023	22.57%
Highest Quarterly Return, Label	rr_HighestQuarterlyReturnLabel	Best Quarter
Highest Quarterly Return, Date	rr_BarChartHighestQuarterlyReturnDate	Dec. 31, 2023
Highest Quarterly Return	rr_BarChartHighestQuarterlyReturn	13.52%
Lowest Quarterly Return, Label	rr_LowestQuarterlyReturnLabel	Worst Quarter
Lowest Quarterly Return, Date	rr_BarChartLowestQuarterlyReturnDate	Jun. 30, 2022
Lowest Quarterly Return	rr_BarChartLowestQuarterlyReturn	(17.80%)
Class A C S I N R T Shares | Janus Henderson Global Sustainable Equity 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	0.75%
Distribution/Service (12b-1) Fees	rr_DistributionAndService12b1FeesOverAssets	none
Other Expenses	rr_OtherExpensesOverAssets	1.22%
Total Annual Fund Operating Expenses	rr_ExpensesOverAssets	1.97%
Fee Waiver and/or Expense Reimbursement	rr_FeeWaiverOrReimbursementOverAssets	1.11%	[1]
Total Annual Fund Operating Expenses After Fee Waiver and/or Expense Reimbursement	rr_NetExpensesOverAssets	0.86%	[1]
1 Year	rr_ExpenseExampleYear01	$ 88
3 Years	rr_ExpenseExampleYear03	511
5 Years	rr_ExpenseExampleYear05	959
10 Years	rr_ExpenseExampleYear10	2,206
1 Year	rr_ExpenseExampleNoRedemptionYear01	88
3 Years	rr_ExpenseExampleNoRedemptionYear03	511
5 Years	rr_ExpenseExampleNoRedemptionYear05	959
10 Years	rr_ExpenseExampleNoRedemptionYear10	$ 2,206
Class A C S I N R T Shares | Janus Henderson Global Sustainable Equity 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	0.75%
Distribution/Service (12b-1) Fees	rr_DistributionAndService12b1FeesOverAssets	0.50%
Other Expenses	rr_OtherExpensesOverAssets	7.40%
Total Annual Fund Operating Expenses	rr_ExpensesOverAssets	8.65%
Fee Waiver and/or Expense Reimbursement	rr_FeeWaiverOrReimbursementOverAssets	7.04%	[1]
Total Annual Fund Operating Expenses After Fee Waiver and/or Expense Reimbursement	rr_NetExpensesOverAssets	1.61%	[1]
1 Year	rr_ExpenseExampleYear01	$ 164
3 Years	rr_ExpenseExampleYear03	1,888
5 Years	rr_ExpenseExampleYear05	3,488
10 Years	rr_ExpenseExampleYear10	7,005
1 Year	rr_ExpenseExampleNoRedemptionYear01	164
3 Years	rr_ExpenseExampleNoRedemptionYear03	1,888
5 Years	rr_ExpenseExampleNoRedemptionYear05	3,488
10 Years	rr_ExpenseExampleNoRedemptionYear10	$ 7,005
Class A C S I N R T Shares | Janus Henderson Global Sustainable Equity 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	0.75%
Distribution/Service (12b-1) Fees	rr_DistributionAndService12b1FeesOverAssets	none
Other Expenses	rr_OtherExpensesOverAssets	1.69%
Total Annual Fund Operating Expenses	rr_ExpensesOverAssets	2.44%
Fee Waiver and/or Expense Reimbursement	rr_FeeWaiverOrReimbursementOverAssets	1.33%	[1]
Total Annual Fund Operating Expenses After Fee Waiver and/or Expense Reimbursement	rr_NetExpensesOverAssets	1.11%	[1]
1 Year	rr_ExpenseExampleYear01	$ 113
3 Years	rr_ExpenseExampleYear03	633
5 Years	rr_ExpenseExampleYear05	1,180
10 Years	rr_ExpenseExampleYear10	2,675
1 Year	rr_ExpenseExampleNoRedemptionYear01	113
3 Years	rr_ExpenseExampleNoRedemptionYear03	633
5 Years	rr_ExpenseExampleNoRedemptionYear05	1,180
10 Years	rr_ExpenseExampleNoRedemptionYear10	$ 2,675
Class A C S I N R T Shares | Janus Henderson Global Sustainable Equity Fund | Return Before Taxes | Class A
Risk Return Abstract	rr_RiskReturnAbstract
1 Year	rr_AverageAnnualReturnYear01	15.27%	[2]
Since Inception	rr_AverageAnnualReturnSinceInception	8.31%	[2]
Inception Date	rr_AverageAnnualReturnInceptionDate	Jun. 25, 2020	[2]
Class A C S I N R T Shares | Janus Henderson Global Sustainable Equity Fund | Return Before Taxes | Class C
Risk Return Abstract	rr_RiskReturnAbstract
1 Year	rr_AverageAnnualReturnYear01	21.28%	[3]
Since Inception	rr_AverageAnnualReturnSinceInception	10.17%	[3]
Inception Date	rr_AverageAnnualReturnInceptionDate	Jun. 25, 2020	[3]
Class A C S I N R T Shares | Janus Henderson Global Sustainable Equity Fund | Return Before Taxes | Class S
Risk Return Abstract	rr_RiskReturnAbstract
1 Year	rr_AverageAnnualReturnYear01	22.59%
Since Inception	rr_AverageAnnualReturnSinceInception	10.25%
Inception Date	rr_AverageAnnualReturnInceptionDate	Jun. 25, 2020
Class A C S I N R T Shares | Janus Henderson Global Sustainable Equity Fund | Return Before Taxes | Class I
Risk Return Abstract	rr_RiskReturnAbstract
1 Year	rr_AverageAnnualReturnYear01	22.57%
Since Inception	rr_AverageAnnualReturnSinceInception	10.33%
Inception Date	rr_AverageAnnualReturnInceptionDate	Jun. 25, 2020
Class A C S I N R T Shares | Janus Henderson Global Sustainable Equity Fund | Return Before Taxes | Class N
Risk Return Abstract	rr_RiskReturnAbstract
1 Year	rr_AverageAnnualReturnYear01	22.70%
Since Inception	rr_AverageAnnualReturnSinceInception	10.42%
Inception Date	rr_AverageAnnualReturnInceptionDate	Jun. 25, 2020
Class A C S I N R T Shares | Janus Henderson Global Sustainable Equity Fund | Return Before Taxes | Class R
Risk Return Abstract	rr_RiskReturnAbstract
1 Year	rr_AverageAnnualReturnYear01	22.55%
Since Inception	rr_AverageAnnualReturnSinceInception	10.18%
Inception Date	rr_AverageAnnualReturnInceptionDate	Jun. 25, 2020
Class A C S I N R T Shares | Janus Henderson Global Sustainable Equity Fund | Return Before Taxes | Class T
Risk Return Abstract	rr_RiskReturnAbstract
1 Year	rr_AverageAnnualReturnYear01	22.49%
Since Inception	rr_AverageAnnualReturnSinceInception	10.17%
Inception Date	rr_AverageAnnualReturnInceptionDate	Jun. 25, 2020
Class A C S I N R T Shares | Janus Henderson Global Sustainable Equity Fund | Return After Taxes on Distributions | Class I
Risk Return Abstract	rr_RiskReturnAbstract
1 Year	rr_AverageAnnualReturnYear01	22.48%
Since Inception	rr_AverageAnnualReturnSinceInception	10.15%
Inception Date	rr_AverageAnnualReturnInceptionDate	Jun. 25, 2020
Class A C S I N R T Shares | Janus Henderson Global Sustainable Equity Fund | Return After Taxes on Distributions and Sale of Fund Shares | Class I
Risk Return Abstract	rr_RiskReturnAbstract
1 Year	rr_AverageAnnualReturnYear01	13.42%
Since Inception	rr_AverageAnnualReturnSinceInception	8.08%
Inception Date	rr_AverageAnnualReturnInceptionDate	Jun. 25, 2020
Class A C S I N R T Shares | Janus Henderson Global Sustainable Equity Fund | MSCI World Index (reflects no deduction for expenses, fees, or taxes, except foreign withholding taxes) | Class A
Risk Return Abstract	rr_RiskReturnAbstract
1 Year	rr_AverageAnnualReturnYear01	23.79%
Since Inception	rr_AverageAnnualReturnSinceInception	12.74%
Class A C S I N R T Shares | Janus Henderson Global Sustainable Equity Fund | MSCI World Index (reflects no deduction for expenses, fees, or taxes, except foreign withholding taxes) | Class C
Risk Return Abstract	rr_RiskReturnAbstract
1 Year	rr_AverageAnnualReturnYear01	23.79%
Since Inception	rr_AverageAnnualReturnSinceInception	12.74%
Class A C S I N R T Shares | Janus Henderson Global Sustainable Equity Fund | MSCI World Index (reflects no deduction for expenses, fees, or taxes, except foreign withholding taxes) | Class S
Risk Return Abstract	rr_RiskReturnAbstract
1 Year	rr_AverageAnnualReturnYear01	23.79%
Since Inception	rr_AverageAnnualReturnSinceInception	12.74%
Class A C S I N R T Shares | Janus Henderson Global Sustainable Equity Fund | MSCI World Index (reflects no deduction for expenses, fees, or taxes, except foreign withholding taxes) | Class I
Risk Return Abstract	rr_RiskReturnAbstract
1 Year	rr_AverageAnnualReturnYear01	23.79%
Since Inception	rr_AverageAnnualReturnSinceInception	12.74%
Class A C S I N R T Shares | Janus Henderson Global Sustainable Equity Fund | MSCI World Index (reflects no deduction for expenses, fees, or taxes, except foreign withholding taxes) | Class N
Risk Return Abstract	rr_RiskReturnAbstract
1 Year	rr_AverageAnnualReturnYear01	23.79%
Since Inception	rr_AverageAnnualReturnSinceInception	12.74%
Class A C S I N R T Shares | Janus Henderson Global Sustainable Equity Fund | MSCI World Index (reflects no deduction for expenses, fees, or taxes, except foreign withholding taxes) | Class R
Risk Return Abstract	rr_RiskReturnAbstract
1 Year	rr_AverageAnnualReturnYear01	23.79%
Since Inception	rr_AverageAnnualReturnSinceInception	12.74%
Class A C S I N R T Shares | Janus Henderson Global Sustainable Equity Fund | MSCI World Index (reflects no deduction for expenses, fees, or taxes, except foreign withholding taxes) | Class T
Risk Return Abstract	rr_RiskReturnAbstract
1 Year	rr_AverageAnnualReturnYear01	23.79%
Since Inception	rr_AverageAnnualReturnSinceInception	12.74%

[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 0.85% 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.