Label	Element	Value
Risk Return Abstract	rr_RiskReturnAbstract
Registrant Name	dei_EntityRegistrantName	JANUS INVESTMENT FUND
Class D Shares | Janus Henderson Asia 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 Asia 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 Asia 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.
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 any performance adjustments to management fees, shareholder servicing fees, such as transfer agency fees (including out-of-pocket costs), brokerage commissions, interest, dividends, taxes, acquired fund fees and expenses, and extraordinary expenses) exceed 0.94% 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 106% of the average value of its portfolio.
Portfolio Turnover, Rate	rr_PortfolioTurnoverRate	106.00%
Expenses Not Correlated to Ratio Due to Acquired Fund Fees [Text]	rr_ExpensesNotCorrelatedToRatioDueToAcquiredFundFees	<span style="font-family:Times New Roman;font-size:7.60pt;">“Acquired Fund” refers to any underlying fund (including, but not limited to, exchange-traded funds) in which a fund invests or has invested during the period. Acquired fund fees and expenses are indirect expenses a fund may incur as a result of investing in shares of an underlying fund. To the extent that the Fund invests in Acquired Funds, the Fund’s “Total Annual Fund Operating Expenses” may not correlate to the “Ratio of gross expenses to average net assets” presented in the Financial Highlights tables because that ratio includes only the direct operating expenses incurred by the Fund, not the indirect costs of investing in Acquired Funds.</span>
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, reinvest all dividends and </span><span style="font-family:Times New Roman;font-size:9.50pt;">distributions, and then redeem all of your Shares at the end of each period. The Example also assumes that your investment has a 5% return each year and that the Fund’s operating expenses are equal to the Total Annual Fund Operating Expenses After Fee Waiver and/or Expense Reimbursement for the first year and the Total Annual Fund Operating Expenses thereafter. Although your actual costs may be higher or lower, based on these assumptions your costs would be:</span>
Expense Example Narrative [Text Block]	rr_ExpenseExampleNarrativeTextBlock	The Example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds.
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 Asian issuers (excluding Japanese issuers). An Asian issuer is generally considered to be any company that (i) is incorporated or has its principal business activities in an Asian country; (ii) is primarily listed on the trading market of an Asian country; or (iii) derives 50% or more of its revenue from, or has 50% or more of its assets in, one or more Asian countries. The Fund considers “Asian countries” to include, but not be limited to, Hong Kong, China, South Korea, Taiwan, Singapore, Malaysia, Thailand, Indonesia, Philippines, India, Vietnam, Pakistan, and Sri Lanka. The Fund may have significant exposure to emerging market countries.The Fund generally invests in a portfolio of 40-70 equity securities, which consist primarily of common stocks, preferred stocks, and depositary receipts, but may also include other types of instruments. The Fund also invests in securities that have contractual restrictions that prohibit or limit their public resale. The Fund intends to diversify its investments across a number of different countries, including emerging market countries. The Fund may also invest in Chinese companies listed on U.S. and other 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.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 a country’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 may engage in active and frequent trading to achieve its investment objective.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.
Risk [Heading]	rr_RiskHeading	<span style="color:#FFFFFF;font-family:Times New Roman;font-size:10.45pt;font-weight:bold;margin-left:0.0pt;text-transform:uppercase;">Principal investment risks</span>
Bar Chart and Performance Table [Heading]	rr_BarChartAndPerformanceTableHeading	<span style="color:#FFFFFF;font-family:Times New Roman;font-size:10.45pt;font-weight:bold;margin-left:0.0pt;text-transform:uppercase;">Performance information</span>
Performance Narrative [Text Block]	rr_PerformanceNarrativeTextBlock	The following information provides some indication of the risks of investing in the Fund by showing how the Fund’s performance has varied over time.The bar chart depicts the change in performance from year to year during the periods indicated. The table compares the Fund’s average annual returns for the periods indicated to a broad-based securities market index. All figures assume reinvestment of dividends and distributions.For certain periods, the Fund’s performance reflects the effect of expense waivers. Without the effect of these expense waivers, the performance shown would have been lower.The Fund’s past performance (before and after taxes) does not necessarily indicate how it will perform in the future. Updated performance information is available at janushenderson.com/allfunds or by calling 1-800-525-3713.
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 table compares the </span><span style="color:#000000;font-family:Times New Roman;font-size:9.50pt;">Fund’s average annual returns for the periods indicated to a broad-based securities market index. All figures assume reinvestment of dividends and distributions.</span>
Performance Additional Market Index [Text]	rr_PerformanceAdditionalMarketIndex	<span style="color:#000000;font-family:Times New Roman;font-size:9.50pt;">The table compares the </span><span style="color:#000000;font-family:Times New Roman;font-size:9.50pt;">Fund’s average annual returns for the periods indicated to a broad-based securities market index. All figures assume reinvestment of dividends and distributions.</span>
Performance Availability Phone [Text]	rr_PerformanceAvailabilityPhone	<span style="color:#000000;font-family:Times New Roman;font-size:9.50pt;font-style:italic;">1-800-525-3713</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/allfunds</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 D Shares (calendar year-end)
Bar Chart Closing [Text Block]	rr_BarChartClosingTextBlock	Best Quarter:2nd Quarter 202018.71%Worst Quarter:1st Quarter 2020– 20.74%
Performance Table Heading	rr_PerformanceTableHeading	Average Annual Total Returns (periods ended 12/31/23)
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 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 All Country Asia ex-Japan Index. The index is described below.•The MSCI All Country Asia ex-Japan Index is designed to measure the equity market performance of Asia, excluding Japan.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.
Performance Table Closing [Text Block]	rr_PerformanceTableClosingTextBlock	Updated performance information is available at janushenderson.com/allfunds or by calling 1-800-525-3713.
Class D Shares | Janus Henderson Asia 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 D Shares | Janus Henderson Asia 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 D Shares | Janus Henderson Asia Equity 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 D Shares | Janus Henderson Asia 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 D Shares | Janus Henderson Asia 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 D Shares | Janus Henderson Asia 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 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 D Shares | Janus Henderson Asia Equity Fund | Geographic Investment Risk [Member]
Risk Return Abstract	rr_RiskReturnAbstract
Risk [Text Block]	rr_RiskTextBlock	Geographic Investment Risk. Because the Fund intends to focus its investments in a particular geographic region, the Fund’s performance is expected to be closely tied to various factors such as social, financial, economic, and political conditions within that region or country. Specifically, the Fund’s investments in Asian issuers increase the Fund’s exposure to the risks associated with volatile securities markets, adverse exchange rates, social, political and regulatory developments, and economic environmental events (such as natural disasters) which may be particular to Asian countries. Events that negatively affect the fiscal stability of Asian countries may cause the value of the Fund’s shares to decrease, in some cases significantly. As a result, the Fund is likely to be more volatile than more geographically diverse funds. In addition, many of the economies of the Asian countries in which the Fund invests are interdependent, which may cause them to experience the impact of such events at the same time or may increase the possibility that conditions in one country or region might adversely impact the issuers of securities in a different country or region.
Class D Shares | Janus Henderson Asia Equity 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 D Shares | Janus Henderson Asia 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 D Shares | Janus Henderson Asia 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 D Shares | Janus Henderson Asia 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 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 D Shares | Janus Henderson Asia Equity Fund | Issuer Concentration Risk [Member]
Risk Return Abstract	rr_RiskReturnAbstract
Risk [Text Block]	rr_RiskTextBlock	Issuer Concentration Risk. The Fund’s portfolio may be comprised of a relatively small number of issuers in comparison to other funds. As a result, the Fund may be subject to greater risks than a fund that invests in a greater number of issuers. A change in the value of any single investment held by the Fund may affect the overall value of the Fund more than it would affect a fund that holds more investments. In particular, the Fund may be more susceptible to adverse developments affecting any single issuer held by the Fund and may be susceptible to greater losses because of these developments.
Class D Shares | Janus Henderson Asia Equity 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 D Shares | Janus Henderson Asia Equity 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 D Shares | Janus Henderson Asia 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 D Shares | Janus Henderson Asia Equity 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 D Shares | Janus Henderson Asia 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 D Shares | Janus Henderson Asia Equity 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 D Shares | Janus Henderson Asia Equity 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 D Shares | Janus Henderson Asia Equity Fund | Portfolio Turnover Risk [Member]
Risk Return Abstract	rr_RiskReturnAbstract
Risk [Text Block]	rr_RiskTextBlock	Portfolio Turnover Risk. Increased portfolio turnover may result in higher costs, which may have a negative effect on the Fund’s performance. In addition, higher portfolio turnover may result in the acceleration of capital gains and the recognition of greater levels of short-term capital gains, which are taxed at ordinary federal income tax rates when distributed to shareholders in a taxable account.
Class D Shares | Janus Henderson Asia Equity 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 D Shares | Janus Henderson Asia 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 Fundwere 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 D Shares | Janus Henderson Asia Equity Fund | Class D
Risk Return Abstract	rr_RiskReturnAbstract
Management Fees	rr_ManagementFeesOverAssets	0.73%	[1]
Other Expenses	rr_OtherExpensesOverAssets	1.30%
Acquired Fund Fees and Expenses	rr_AcquiredFundFeesAndExpensesOverAssets	0.01%	[2]
Total Annual Fund Operating Expenses	rr_ExpensesOverAssets	2.04%
Fee Waiver and/or Expense Reimbursement	rr_FeeWaiverOrReimbursementOverAssets	1.11%	[3]
Total Annual Fund Operating Expenses After Fee Waiver and/or Expense Reimbursement	rr_NetExpensesOverAssets	0.93%	[3]
1 Year	rr_ExpenseExampleYear01	$ 95
3 Years	rr_ExpenseExampleYear03	532
5 Years	rr_ExpenseExampleYear05	996
10 Years	rr_ExpenseExampleYear10	$ 2,280
2014	rr_AnnualReturn2014	8.11%
2015	rr_AnnualReturn2015	(7.50%)
2016	rr_AnnualReturn2016	6.50%
2017	rr_AnnualReturn2017	39.42%
2018	rr_AnnualReturn2018	(14.43%)
2019	rr_AnnualReturn2019	20.80%
2020	rr_AnnualReturn2020	27.07%
2021	rr_AnnualReturn2021	(11.15%)
2022	rr_AnnualReturn2022	(25.26%)
2023	rr_AnnualReturn2023	4.60%
Highest Quarterly Return, Label	rr_HighestQuarterlyReturnLabel	Best Quarter
Highest Quarterly Return, Date	rr_BarChartHighestQuarterlyReturnDate	Jun. 30, 2020
Highest Quarterly Return	rr_BarChartHighestQuarterlyReturn	18.71%
Lowest Quarterly Return, Label	rr_LowestQuarterlyReturnLabel	Worst Quarter
Lowest Quarterly Return, Date	rr_BarChartLowestQuarterlyReturnDate	Mar. 31, 2020
Lowest Quarterly Return	rr_BarChartLowestQuarterlyReturn	(20.74%)
Class D Shares | Janus Henderson Asia Equity Fund | Return Before Taxes | Class D
Risk Return Abstract	rr_RiskReturnAbstract
1 Year	rr_AverageAnnualReturnYear01	4.60%
5 Years	rr_AverageAnnualReturnYear05	1.29%
10 Years	rr_AverageAnnualReturnYear10	3.08%
Since Inception	rr_AverageAnnualReturnSinceInception	2.41%
Inception Date	rr_AverageAnnualReturnInceptionDate	Jul. 29, 2011
Class D Shares | Janus Henderson Asia Equity Fund | Return After Taxes on Distributions | Class D
Risk Return Abstract	rr_RiskReturnAbstract
1 Year	rr_AverageAnnualReturnYear01	4.80%
5 Years	rr_AverageAnnualReturnYear05	1.27%
10 Years	rr_AverageAnnualReturnYear10	2.56%
Since Inception	rr_AverageAnnualReturnSinceInception	1.88%
Inception Date	rr_AverageAnnualReturnInceptionDate	Jul. 29, 2011
Class D Shares | Janus Henderson Asia Equity Fund | Return After Taxes on Distributions and Sale of Fund Shares | Class D
Risk Return Abstract	rr_RiskReturnAbstract
1 Year	rr_AverageAnnualReturnYear01	2.92%	[4]
5 Years	rr_AverageAnnualReturnYear05	1.13%	[4]
10 Years	rr_AverageAnnualReturnYear10	2.48%	[4]
Since Inception	rr_AverageAnnualReturnSinceInception	1.91%	[4]
Inception Date	rr_AverageAnnualReturnInceptionDate	Jul. 29, 2011	[4]
Class D Shares | Janus Henderson Asia Equity Fund | MSCI All Country Asia ex-Japan Index (reflects no deduction for expenses, fees, or taxes, except foreign withholding taxes)
Risk Return Abstract	rr_RiskReturnAbstract
1 Year	rr_AverageAnnualReturnYear01	5.98%
5 Years	rr_AverageAnnualReturnYear05	3.69%
10 Years	rr_AverageAnnualReturnYear10	3.86%
Since Inception	rr_AverageAnnualReturnSinceInception	3.25%

[1] This fee may adjust up or down monthly based on the Fund’s performance relative to its benchmark index over the performance measurement period. For more information regarding performance-based advisory fees, refer to “Management Expenses” in the Fund’s Prospectus.

[2] “Acquired Fund” refers to any underlying fund (including, but not limited to, exchange-traded funds) in which a fund invests or has invested during the period. Acquired fund fees and expenses are indirect expenses a fund may incur as a result of investing in shares of an underlying fund. To the extent that the Fund invests in Acquired Funds, the Fund’s “Total Annual Fund Operating Expenses” may not correlate to the “Ratio of gross expenses to average net assets” presented in the Financial Highlights tables because that ratio includes only the direct operating expenses incurred by the Fund, not the indirect costs of investing in Acquired Funds.

[3] 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 any performance adjustments to management fees, shareholder servicing fees, such as transfer agency fees (including out-of-pocket costs), brokerage commissions, interest, dividends, taxes, acquired fund fees and expenses, and extraordinary expenses) exceed 0.94% 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.

[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.