Label	Element	Value
Risk Return Abstract	rr_RiskReturnAbstract
Registrant Name	dei_EntityRegistrantName	JANUS INVESTMENT FUND
Class A C S I N T Shares | Janus Henderson Emerging Markets 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 Emerging Markets 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 Emerging Markets 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, taxes, acquired fund fees and expenses, and extraordinary expenses) exceed 1.03% 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="color:#000000;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 63% of the average value of its portfolio.
Portfolio Turnover, Rate	rr_PortfolioTurnoverRate	63.00%
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 of companies in emerging market countries. Equity securities include common stocks and related securities, such as preferred stock and convertible securities. The Fund also invests in securities that have contractual restrictions that prohibit or limit their public resale. Emerging market countries are all countries represented by the MSCI Emerging Markets Indexsm and/or those countries considered to be developing by the World Bank, the International Finance Corporation or the United Nations. These countries typically are located in the Asia-Pacific region, Eastern Europe, Central and South America, and Africa.Companies in emerging market countries are broadly defined to include any company that meets one or more of the following tests: (i) its country of organization, its primary business office, and/or the principal trading market of its stock are located in an emerging market country; (ii) 50% or more of its assets are located in emerging market countries, (iii) 50% or more of its revenues are derived from emerging market countries; or (iv) a company with similar emerging markets exposure.In addition to the Fund’s main investments, the Fund may invest no more than 20% of its net assets in the securities of issuers in developed market countries.The Fund may invest in derivatives. Derivative instruments have a value derived from, or directly linked to, an underlying asset, such as equity securities, fixed-income securities, commodities, currencies, interest rates, or market indices. In particular, the Fund may invest in derivatives such as futures, options, forward currency contracts, warrants, and swaps (including total return swaps) for various investment purposes, such as to gain exposure to a particular portion of the market or to manage or hedge portfolio risk.Portfolio management employs both a “top-down” and “bottom-up” approach to select investments for the Fund. The top-down approach involves a macro analysis of factors that include an issuer’s economic growth profile, the stages of a country’s development, and trends in a country’s governance and regulatory framework. The bottom-up analysis focuses on fundamental research and considers, among other factors, a company’s valuation, growth potential, competitive positioning, projected future earnings, cash flows, governance, and dividends. The Fund has the ability to invest more heavily in either growth or value securities depending on market conditions and portfolio management’s convictions.The Fund will generally consider selling a stock when, in portfolio management’s opinion, there is a deterioration in the factors considered in selecting investments for the Fund, including changes in a country’s stage of development, governance, or regulatory framework. The Fund will also consider selling a stock when, in portfolio management’s opinion, a company’s fundamentals or a company’s revenue growth has slowed, or there has been changes in a company’s risk/reward potential.At times, the Fund may invest to a significant degree in issuers located in a single country or region, which particularly includes China, or may also invest in Chinese companies listed on U.S. exchanges structured as variable interest entities. In addition, the Fund may invest in securities issued by small- and mid-sized companies and in less seasoned issuers.
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. Returns shown for periods prior to June 5, 2017, are those of Henderson Emerging Markets Fund (the “Predecessor Fund”). The Predecessor Fund was advised by Henderson Global Investors (North America) Inc. and subadvised by Henderson Investment Management Limited. Class A Shares, Class C Shares, Class I Shares, and Class R6 Shares of the Predecessor Fund were reorganized into Class A Shares, Class C Shares, Class I Shares, and Class N Shares, respectively, of the Fund on June 2, 2017. Class A Shares, Class C Shares, and Class I Shares of the Predecessor Fund commenced operations with the Predecessor Fund’s inception on December 31, 2010. Class R6 Shares of the Predecessor Fund commenced operations on November 30, 2015. Class S Shares and Class T Shares of the Fund commenced operations on June 5, 2017.•The performance shown for Class A Shares for periods prior to June 5, 2017, reflects the performance of Class A Shares of the Predecessor Fund and is calculated using the fees and expenses of Class A Shares of the Predecessor Fund, in effect during the periods shown, net of any applicable fee and expense limitations or waivers.•The performance shown for Class C Shares for periods prior to June 5, 2017, reflects the performance of Class C Shares of the Predecessor Fund and is calculated using the fees and expenses of Class C Shares of the Predecessor Fund, in effect during the periods shown, net of any applicable fee and expense limitations or waivers.•The performance shown for Class I Shares for periods prior to June 5, 2017, reflects the performance of Class I Shares of the Predecessor Fund and is calculated using the fees and expenses of Class I Shares of the Predecessor Fund, in effect during the periods shown, net of any applicable fee and expense limitations or waivers.•The performance shown for Class N Shares for periods prior to June 5, 2017, reflects the performance of Class R6 Shares of the Predecessor Fund and is calculated using the fees and expenses of Class R6 Shares of the Predecessor Fund, in effect during the periods shown, net of any applicable fee and expense limitations or waivers, except that for periods prior to November 30, 2015, performance shown for Class N Shares reflects the performance of Class I Shares of the Predecessor Fund, calculated using the estimated fees and expenses of Class N Shares, net of any applicable fee and expense limitations or waivers.•The performance shown for Class S Shares for periods prior to June 5, 2017, reflects the performance of Class I Shares of the Predecessor Fund, calculated using the estimated fees and expenses of Class S Shares, net of any applicable fee and expense limitations or waivers.•The performance shown for Class T Shares for periods prior to June 5, 2017, reflects the performance of Class I Shares of the Predecessor Fund, calculated using the estimated fees and expenses of Class T Shares, net of any applicable fee and expense limitations or waivers.Returns of the Fund will be different from the Predecessor Fund as they have different expenses.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 (and the Predecessor Fund’s) past performance (before and after taxes) does not necessarily indicate how the Fund will perform in the future.Updated performance information is available at janushenderson.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 periods indicated. </span><span style="font-family:Times New Roman;font-size:9.50pt;">The bar chart figures do not </span><span style="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="font-family:Times New Roman;font-size:9.50pt;">The table compares the Fund’s average annual returns for </span><span style="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="font-family:Times New Roman;font-size:9.50pt;">The table compares the Fund’s average annual returns for </span><span style="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 (and the Predecessor Fund’s) past performance (before and after taxes) does not necessarily indicate how the Fund 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="font-family:Times New Roman;font-size:9.50pt;">The bar chart figures do not </span><span style="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 202023.91%Worst Quarter:1st Quarter 2020– 24.92%
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 </span><span style="color:#000000;font-family:Times New Roman;font-size:9.50pt;">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 </span><span style="color:#000000;font-family:Times New Roman;font-size:9.50pt;">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.</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 Explanation after Tax Higher	rr_PerformanceTableExplanationAfterTaxHigher	<span style="color:#000000;font-family:Times New Roman;font-size:7.60pt;">If the Fund incurs a loss, which generates a tax benefit, the Return After Taxes on Distributions and Sale of Fund Shares may exceed the Fund’s other return figures.</span>
Performance Table Narrative	rr_PerformanceTableNarrativeTextBlock	The Fund’s primary benchmark index is the MSCI Emerging Markets Index. The index is described below.•The MSCI Emerging Markets Index is designed to measure equity market performance of emerging markets.After-tax returns are calculated using distributions for the Predecessor Fund’s Class I Shares for the period prior to June 5, 2017. If Class I Shares of the Fund had been available during periods prior to June 5, 2017, the distributions used to calculate the after-tax returns may have been different. 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 at janushenderson.com/performance or by calling 1-877-335-2687.
Class A C S I N T Shares | Janus Henderson Emerging Markets 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 T Shares | Janus Henderson Emerging Markets 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 T Shares | Janus Henderson Emerging Markets Fund | Emerging Markets Risk [Member]
Risk Return Abstract	rr_RiskReturnAbstract
Risk [Text Block]	rr_RiskTextBlock	Emerging Markets Risk. Emerging market securities involve a number of risks, which may result from less government supervision and regulation of business and industry practices (including the potential lack of strict finance and accounting controls and standards), stock exchanges, brokers, and listed companies. Information about emerging market companies, including financial information, may be less available or reliable and the Adviser’s ability to conduct due diligence with respect to such companies may be limited. Accordingly, these investments may be potentially more volatile in price and less liquid than investments in developed securities markets, resulting in greater risk to investors. There is a risk in developing countries that a current or future economic or political crisis could lead to price controls, forced mergers of companies, expropriation or confiscatory taxation, imposition or enforcement of foreign ownership limits, seizure, nationalization, sanctions or imposition of restrictions by various governmental entities on investment and trading, or creation of government monopolies, any of which may have a detrimental effect on the Fund’s investments. In addition, the taxation systems at the federal, regional, and local levels in developing or emerging market countries may be less transparent, inconsistently enforced, and subject to change. Emerging markets may be subject to a higher degree of corruption and fraud than developed markets,and financial institutions and transaction counterparties may have less financial sophistication, creditworthiness, and/or resources than participants in developed markets. Additionally, foreign and emerging market risks, including but not limited to price controls, expropriation or confiscatory taxation, imposition or enforcement of foreign ownership limits, nationalization, and restrictions on repatriation of assets may be heightened to the extent the Fund invests in Chinese or other local market securities. Foreign and emerging market risks may also be heightened to the extent the Fund has exposure to Chinese issuers through variable interest entities, which subjects the Fund to the risks associated with the underlying Chinese issuer or operating company.
Class A C S I N T Shares | Janus Henderson Emerging Markets 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 T Shares | Janus Henderson Emerging Markets 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 T Shares | Janus Henderson Emerging Markets 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 T Shares | Janus Henderson Emerging Markets Fund | Geographic Concentration Risk [Member]
Risk Return Abstract	rr_RiskReturnAbstract
Risk [Text Block]	rr_RiskTextBlock	Geographic Concentration Risk. To the extent the Fund invests a substantial amount of its assets in issuers located in a single country or region, the economic, political, social, regulatory, or other developments or conditions within such country or region will generally have a greater effect on the Fund than they would on a more geographically diversified fund, which may result in greater losses and volatility. Adverse developments in certain regions could also adversely affect securities of other countries whose economies appear to be unrelated and could have a negative impact on the Fund’s performance.
Class A C S I N T Shares | Janus Henderson Emerging Markets Fund | China Risk [Member]
Risk Return Abstract	rr_RiskReturnAbstract
Risk [Text Block]	rr_RiskTextBlock	•China Risk. The value of securities of companies that derive the majority of their revenues from China is likely to be more volatile than that of other issuers. The economy of China differs, often unfavorably, from the U.S. economy in such respects as structure, general development, government involvement, wealth distribution, rate of inflation, growth rate, allocation of resources and capital reinvestment. The Chinese central government historically has exercised substantial control over virtually every sector of the Chinese economy through administrative regulation and/or state ownership. Actions of the Chinese government authorities continue to have a substantial effect on economic conditions in China. It is difficult for non-Chinese investors to directly access securities in China because of investment and trading restrictions. These limitations and restrictions may impact the availability, liquidity, and pricing of certain securities.
Class A C S I N T Shares | Janus Henderson Emerging Markets 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 T Shares | Janus Henderson Emerging Markets 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 T Shares | Janus Henderson Emerging Markets 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 T Shares | Janus Henderson Emerging Markets 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 T Shares | Janus Henderson Emerging Markets 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 A C S I N T Shares | Janus Henderson Emerging Markets 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 T Shares | Janus Henderson Emerging Markets Fund | Derivatives Risk [Member]
Risk Return Abstract	rr_RiskReturnAbstract
Risk [Text Block]	rr_RiskTextBlock	Derivatives Risk. Derivatives can be volatile and involve risks in addition to the risks of the underlying referenced securities or asset. Gains or losses from a derivative investment can be substantially greater than the derivative’s original cost, and can therefore involve leverage. Leverage may cause the Fund to be more volatile than if it had not used leverage. Derivatives can be complex instruments and may involve analysis that differs from that required for other investment types used by theFund. If the value of a derivative does not correlate well with the particular market or other asset class to which the derivative is intended to provide exposure, the derivative may not produce the anticipated result. Derivatives can also reduce the opportunity for gain or result in losses by offsetting positive returns in other investments. Derivatives entail the risk that the counterparty will default on its payment obligations. If the counterparty to a derivative transaction defaults, the Fund would risk the loss of the net amount of the payments that it contractually is entitled to receive. Derivatives used for hedging purposes may reduce or eliminate gains or cause losses if the market moves in a manner different from that anticipated by portfolio management or if the cost of the derivative outweighs the benefit of the hedge.
Class A C S I N T Shares | Janus Henderson Emerging Markets Fund | Restricted Securities Risk [Member]
Risk Return Abstract	rr_RiskReturnAbstract
Risk [Text Block]	rr_RiskTextBlock	Rule 144A Securities and Other Exempt Securities Risk. Investments in securities issued under Regulation S and Rule 144Aand other securities exempt from certain registration requirements could have the effect of decreasing the Fund’s liquidity profile or preventing the Fund from disposing of them promptly at advantageous prices. Investments in securities exempt from certain registration requirements may be less liquid than other investments because such securities may not always be readily sold in broad public markets and may have no active trading market. As a result, they may be difficult to value because market quotations may not be readily available.
Class A C S I N T Shares | Janus Henderson Emerging Markets Fund | Convertible Securities Risk [Member]
Risk Return Abstract	rr_RiskReturnAbstract
Risk [Text Block]	rr_RiskTextBlock	Convertible Securities Risk. The Fund may invest in securities that are convertible into preferred and common stocks, and thus, is subject to the risks of investments in both debt and equity securities. The market value of convertible securities tends to decline as interest rates increase and, conversely, tends to increase as interest rates decline. In addition, because of the conversion feature, the market value of convertible securities tends to vary with fluctuations in the market value of the underlying preferred and common stocks and, therefore, also will react to variations in the general market for equity securities.
Class A C S I N T Shares | Janus Henderson Emerging Markets Fund | Preferred Stock Risk [Member]
Risk Return Abstract	rr_RiskReturnAbstract
Risk [Text Block]	rr_RiskTextBlock	Preferred Stock Risk. Preferred stock is subject to similar risks as common stock and debt securities. Typically, a rise in interest rates causes a decline in the value of preferred stock. Preferred stocks are also subject to credit risk, which is the possibility that an issuer of preferred stock will fail to make its dividend payments.
Class A C S I N T Shares | Janus Henderson Emerging Markets 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 A C S I N T Shares | Janus Henderson Emerging Markets 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	1.00%
Distribution/Service (12b-1) Fees	rr_DistributionAndService12b1FeesOverAssets	0.25%
Other Expenses	rr_OtherExpensesOverAssets	0.71%
Total Annual Fund Operating Expenses	rr_ExpensesOverAssets	1.96%
Fee Waiver and/or Expense Reimbursement	rr_FeeWaiverOrReimbursementOverAssets	0.58%	[1]
Total Annual Fund Operating Expenses After Fee Waiver and/or Expense Reimbursement	rr_NetExpensesOverAssets	1.38%	[1]
1 Year	rr_ExpenseExampleYear01	$ 707
3 Years	rr_ExpenseExampleYear03	1,102
5 Years	rr_ExpenseExampleYear05	1,521
10 Years	rr_ExpenseExampleYear10	2,685
1 Year	rr_ExpenseExampleNoRedemptionYear01	707
3 Years	rr_ExpenseExampleNoRedemptionYear03	1,102
5 Years	rr_ExpenseExampleNoRedemptionYear05	1,521
10 Years	rr_ExpenseExampleNoRedemptionYear10	$ 2,685
Class A C S I N T Shares | Janus Henderson Emerging Markets 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	1.00%
Distribution/Service (12b-1) Fees	rr_DistributionAndService12b1FeesOverAssets	1.00%
Other Expenses	rr_OtherExpensesOverAssets	0.98%
Total Annual Fund Operating Expenses	rr_ExpensesOverAssets	2.98%
Fee Waiver and/or Expense Reimbursement	rr_FeeWaiverOrReimbursementOverAssets	0.85%	[1]
Total Annual Fund Operating Expenses After Fee Waiver and/or Expense Reimbursement	rr_NetExpensesOverAssets	2.13%	[1]
1 Year	rr_ExpenseExampleYear01	$ 316
3 Years	rr_ExpenseExampleYear03	842
5 Years	rr_ExpenseExampleYear05	1,493
10 Years	rr_ExpenseExampleYear10	2,998
1 Year	rr_ExpenseExampleNoRedemptionYear01	216
3 Years	rr_ExpenseExampleNoRedemptionYear03	842
5 Years	rr_ExpenseExampleNoRedemptionYear05	1,493
10 Years	rr_ExpenseExampleNoRedemptionYear10	$ 2,998
Class A C S I N T Shares | Janus Henderson Emerging Markets 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	1.00%
Distribution/Service (12b-1) Fees	rr_DistributionAndService12b1FeesOverAssets	0.25%
Other Expenses	rr_OtherExpensesOverAssets	4.46%
Total Annual Fund Operating Expenses	rr_ExpensesOverAssets	5.71%
Fee Waiver and/or Expense Reimbursement	rr_FeeWaiverOrReimbursementOverAssets	4.17%	[1]
Total Annual Fund Operating Expenses After Fee Waiver and/or Expense Reimbursement	rr_NetExpensesOverAssets	1.54%	[1]
1 Year	rr_ExpenseExampleYear01	$ 157
3 Years	rr_ExpenseExampleYear03	1,330
5 Years	rr_ExpenseExampleYear05	2,486
10 Years	rr_ExpenseExampleYear10	5,307
1 Year	rr_ExpenseExampleNoRedemptionYear01	157
3 Years	rr_ExpenseExampleNoRedemptionYear03	1,330
5 Years	rr_ExpenseExampleNoRedemptionYear05	2,486
10 Years	rr_ExpenseExampleNoRedemptionYear10	$ 5,307
Class A C S I N T Shares | Janus Henderson Emerging Markets 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	1.00%
Distribution/Service (12b-1) Fees	rr_DistributionAndService12b1FeesOverAssets	none
Other Expenses	rr_OtherExpensesOverAssets	0.65%
Total Annual Fund Operating Expenses	rr_ExpensesOverAssets	1.65%
Fee Waiver and/or Expense Reimbursement	rr_FeeWaiverOrReimbursementOverAssets	0.52%	[1]
Total Annual Fund Operating Expenses After Fee Waiver and/or Expense Reimbursement	rr_NetExpensesOverAssets	1.13%	[1]
1 Year	rr_ExpenseExampleYear01	$ 115
3 Years	rr_ExpenseExampleYear03	470
5 Years	rr_ExpenseExampleYear05	848
10 Years	rr_ExpenseExampleYear10	1,911
1 Year	rr_ExpenseExampleNoRedemptionYear01	115
3 Years	rr_ExpenseExampleNoRedemptionYear03	470
5 Years	rr_ExpenseExampleNoRedemptionYear05	848
10 Years	rr_ExpenseExampleNoRedemptionYear10	$ 1,911
2014	rr_AnnualReturn2014	(2.81%)
2015	rr_AnnualReturn2015	(10.43%)
2016	rr_AnnualReturn2016	9.96%
2017	rr_AnnualReturn2017	29.83%
2018	rr_AnnualReturn2018	(16.54%)
2019	rr_AnnualReturn2019	13.88%
2020	rr_AnnualReturn2020	22.74%
2021	rr_AnnualReturn2021	(1.60%)
2022	rr_AnnualReturn2022	(26.51%)
2023	rr_AnnualReturn2023	7.70%
Highest Quarterly Return, Label	rr_HighestQuarterlyReturnLabel	Best Quarter
Highest Quarterly Return, Date	rr_BarChartHighestQuarterlyReturnDate	Jun. 30, 2020
Highest Quarterly Return	rr_BarChartHighestQuarterlyReturn	23.91%
Lowest Quarterly Return, Label	rr_LowestQuarterlyReturnLabel	Worst Quarter
Lowest Quarterly Return, Date	rr_BarChartLowestQuarterlyReturnDate	Mar. 31, 2020
Lowest Quarterly Return	rr_BarChartLowestQuarterlyReturn	(24.92%)
Class A C S I N T Shares | Janus Henderson Emerging Markets 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	1.00%
Distribution/Service (12b-1) Fees	rr_DistributionAndService12b1FeesOverAssets	none
Other Expenses	rr_OtherExpensesOverAssets	0.53%
Total Annual Fund Operating Expenses	rr_ExpensesOverAssets	1.53%
Fee Waiver and/or Expense Reimbursement	rr_FeeWaiverOrReimbursementOverAssets	0.49%	[1]
Total Annual Fund Operating Expenses After Fee Waiver and/or Expense Reimbursement	rr_NetExpensesOverAssets	1.04%	[1]
1 Year	rr_ExpenseExampleYear01	$ 106
3 Years	rr_ExpenseExampleYear03	435
5 Years	rr_ExpenseExampleYear05	788
10 Years	rr_ExpenseExampleYear10	1,782
1 Year	rr_ExpenseExampleNoRedemptionYear01	106
3 Years	rr_ExpenseExampleNoRedemptionYear03	435
5 Years	rr_ExpenseExampleNoRedemptionYear05	788
10 Years	rr_ExpenseExampleNoRedemptionYear10	$ 1,782
Class A C S I N T Shares | Janus Henderson Emerging Markets 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	1.00%
Distribution/Service (12b-1) Fees	rr_DistributionAndService12b1FeesOverAssets	none
Other Expenses	rr_OtherExpensesOverAssets	0.97%
Total Annual Fund Operating Expenses	rr_ExpensesOverAssets	1.97%
Fee Waiver and/or Expense Reimbursement	rr_FeeWaiverOrReimbursementOverAssets	0.69%	[1]
Total Annual Fund Operating Expenses After Fee Waiver and/or Expense Reimbursement	rr_NetExpensesOverAssets	1.28%	[1]
1 Year	rr_ExpenseExampleYear01	$ 130
3 Years	rr_ExpenseExampleYear03	552
5 Years	rr_ExpenseExampleYear05	999
10 Years	rr_ExpenseExampleYear10	2,240
1 Year	rr_ExpenseExampleNoRedemptionYear01	130
3 Years	rr_ExpenseExampleNoRedemptionYear03	552
5 Years	rr_ExpenseExampleNoRedemptionYear05	999
10 Years	rr_ExpenseExampleNoRedemptionYear10	$ 2,240
Class A C S I N T Shares | Janus Henderson Emerging Markets Fund | Return Before Taxes | Class A
Risk Return Abstract	rr_RiskReturnAbstract
1 Year	rr_AverageAnnualReturnYear01	1.32%	[2]
5 Years	rr_AverageAnnualReturnYear05	0.26%	[2]
10 Years	rr_AverageAnnualReturnYear10	0.37%	[2]
Since Inception	rr_AverageAnnualReturnSinceInception	(0.25%)	[2]
Inception Date	rr_AverageAnnualReturnInceptionDate	Dec. 31, 2010	[2]
Class A C S I N T Shares | Janus Henderson Emerging Markets Fund | Return Before Taxes | Class C
Risk Return Abstract	rr_RiskReturnAbstract
1 Year	rr_AverageAnnualReturnYear01	5.62%	[3]
5 Years	rr_AverageAnnualReturnYear05	0.72%	[3]
10 Years	rr_AverageAnnualReturnYear10	0.21%	[3]
Since Inception	rr_AverageAnnualReturnSinceInception	(0.54%)	[3]
Inception Date	rr_AverageAnnualReturnInceptionDate	Dec. 31, 2010	[3]
Class A C S I N T Shares | Janus Henderson Emerging Markets Fund | Return Before Taxes | Class S
Risk Return Abstract	rr_RiskReturnAbstract
1 Year	rr_AverageAnnualReturnYear01	7.27%
5 Years	rr_AverageAnnualReturnYear05	1.39%
10 Years	rr_AverageAnnualReturnYear10	0.78%
Since Inception	rr_AverageAnnualReturnSinceInception	(0.01%)
Inception Date	rr_AverageAnnualReturnInceptionDate	Dec. 31, 2010
Class A C S I N T Shares | Janus Henderson Emerging Markets Fund | Return Before Taxes | Class I
Risk Return Abstract	rr_RiskReturnAbstract
1 Year	rr_AverageAnnualReturnYear01	7.70%
5 Years	rr_AverageAnnualReturnYear05	1.71%
10 Years	rr_AverageAnnualReturnYear10	1.22%
Since Inception	rr_AverageAnnualReturnSinceInception	0.46%
Inception Date	rr_AverageAnnualReturnInceptionDate	Dec. 31, 2010
Class A C S I N T Shares | Janus Henderson Emerging Markets Fund | Return Before Taxes | Class N
Risk Return Abstract	rr_RiskReturnAbstract
1 Year	rr_AverageAnnualReturnYear01	7.84%
5 Years	rr_AverageAnnualReturnYear05	1.80%
10 Years	rr_AverageAnnualReturnYear10	1.21%
Since Inception	rr_AverageAnnualReturnSinceInception	0.39%
Inception Date	rr_AverageAnnualReturnInceptionDate	Dec. 31, 2010
Class A C S I N T Shares | Janus Henderson Emerging Markets Fund | Return Before Taxes | Class T
Risk Return Abstract	rr_RiskReturnAbstract
1 Year	rr_AverageAnnualReturnYear01	7.57%
5 Years	rr_AverageAnnualReturnYear05	1.56%
10 Years	rr_AverageAnnualReturnYear10	0.97%
Since Inception	rr_AverageAnnualReturnSinceInception	0.19%
Inception Date	rr_AverageAnnualReturnInceptionDate	Dec. 31, 2010
Class A C S I N T Shares | Janus Henderson Emerging Markets Fund | Return After Taxes on Distributions | Class I
Risk Return Abstract	rr_RiskReturnAbstract
1 Year	rr_AverageAnnualReturnYear01	7.73%
5 Years	rr_AverageAnnualReturnYear05	1.49%
10 Years	rr_AverageAnnualReturnYear10	0.98%
Since Inception	rr_AverageAnnualReturnSinceInception	0.24%
Inception Date	rr_AverageAnnualReturnInceptionDate	Dec. 31, 2010
Class A C S I N T Shares | Janus Henderson Emerging Markets Fund | Return After Taxes on Distributions and Sale of Fund Shares | Class I
Risk Return Abstract	rr_RiskReturnAbstract
1 Year	rr_AverageAnnualReturnYear01	4.87%	[4]
5 Years	rr_AverageAnnualReturnYear05	1.45%	[4]
10 Years	rr_AverageAnnualReturnYear10	1.07%	[4]
Since Inception	rr_AverageAnnualReturnSinceInception	0.45%	[4]
Inception Date	rr_AverageAnnualReturnInceptionDate	Dec. 31, 2010	[4]
Class A C S I N T Shares | Janus Henderson Emerging Markets Fund | MSCI Emerging Markets Index (reflects no deduction for expenses, fees, or taxes, except foreign withholding taxes) | Class A
Risk Return Abstract	rr_RiskReturnAbstract
1 Year	rr_AverageAnnualReturnYear01	9.83%
5 Years	rr_AverageAnnualReturnYear05	3.68%
10 Years	rr_AverageAnnualReturnYear10	2.66%
Since Inception	rr_AverageAnnualReturnSinceInception	1.55%
Class A C S I N T Shares | Janus Henderson Emerging Markets Fund | MSCI Emerging Markets Index (reflects no deduction for expenses, fees, or taxes, except foreign withholding taxes) | Class C
Risk Return Abstract	rr_RiskReturnAbstract
1 Year	rr_AverageAnnualReturnYear01	9.83%
5 Years	rr_AverageAnnualReturnYear05	3.68%
10 Years	rr_AverageAnnualReturnYear10	2.66%
Since Inception	rr_AverageAnnualReturnSinceInception	1.55%
Class A C S I N T Shares | Janus Henderson Emerging Markets Fund | MSCI Emerging Markets Index (reflects no deduction for expenses, fees, or taxes, except foreign withholding taxes) | Class S
Risk Return Abstract	rr_RiskReturnAbstract
1 Year	rr_AverageAnnualReturnYear01	9.83%
5 Years	rr_AverageAnnualReturnYear05	3.68%
10 Years	rr_AverageAnnualReturnYear10	2.66%
Since Inception	rr_AverageAnnualReturnSinceInception	1.55%
Class A C S I N T Shares | Janus Henderson Emerging Markets Fund | MSCI Emerging Markets Index (reflects no deduction for expenses, fees, or taxes, except foreign withholding taxes) | Class I
Risk Return Abstract	rr_RiskReturnAbstract
1 Year	rr_AverageAnnualReturnYear01	9.83%
5 Years	rr_AverageAnnualReturnYear05	3.68%
10 Years	rr_AverageAnnualReturnYear10	2.66%
Since Inception	rr_AverageAnnualReturnSinceInception	1.55%
Class A C S I N T Shares | Janus Henderson Emerging Markets Fund | MSCI Emerging Markets Index (reflects no deduction for expenses, fees, or taxes, except foreign withholding taxes) | Class N
Risk Return Abstract	rr_RiskReturnAbstract
1 Year	rr_AverageAnnualReturnYear01	9.83%
5 Years	rr_AverageAnnualReturnYear05	3.68%
10 Years	rr_AverageAnnualReturnYear10	2.66%
Since Inception	rr_AverageAnnualReturnSinceInception	1.55%
Class A C S I N T Shares | Janus Henderson Emerging Markets Fund | MSCI Emerging Markets Index (reflects no deduction for expenses, fees, or taxes, except foreign withholding taxes) | Class T
Risk Return Abstract	rr_RiskReturnAbstract
1 Year	rr_AverageAnnualReturnYear01	9.83%
5 Years	rr_AverageAnnualReturnYear05	3.68%
10 Years	rr_AverageAnnualReturnYear10	2.66%
Since Inception	rr_AverageAnnualReturnSinceInception	1.55%

[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 1.03% 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.

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