Label	Element	Value
Risk Return Abstract	rr_RiskReturnAbstract
Registrant Name	dei_EntityRegistrantName	JANUS INVESTMENT FUND
Prospectus Date	rr_ProspectusDate	Jan. 28, 2022
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:0.0%;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:0.0%;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 and hold 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), administrative services fees, brokerage commissions, interest, dividends, taxes, acquired fund fees and expenses, and extraordinary expenses) exceed 0.99% for at least a one-year period commencing on January 28, 2022. The contractual waiver may be terminated or modified prior to this date 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 60% of the average value of its portfolio.
Portfolio Turnover, Rate	rr_PortfolioTurnoverRate	60.00%
Expense Example [Heading]	rr_ExpenseExampleHeading	<span style="color:#000000;font-family:Times New Roman;font-size:9.50pt;font-weight:bold;margin-left:3pt;">EXAMPLE:</span>
Expense Example by Year [Heading]	rr_ExpenseExampleByYearHeading	<span style="color:#000000;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 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 without waivers remain the same. 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 following Example is based on expenses without waivers. 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:0.0%;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. Subject to the Fund’s 80% investment policy, the Fund may also invest in issuers from other countries, including Australia and New Zealand. The Fund may have significant exposure to emerging market countries.The Fund generally invests in equity securities, which consist primarily of common stocks, preferred stocks, depositary receipts, and convertible securities, but may also include other types of instruments, such as equity-linked securities, real estate-related companies, and real estate investment trusts sponsored by Asian real estate companies. The Fund may invest in companies of any market capitalization. While the Fund intends to diversify its investments across a number of different countries, including emerging market countries, it may, under unusual circumstances, invest all or a significant portion of its assets in a single Asian country. The Fund may also invest in Chinese companies listed on U.S. exchanges structured as variable interest entities.The portfolio managers apply two key principles when investing in Asian equities. First, the portfolio managers use fundamental research to identify high quality companies which, if bought at the right price, are expected to produce outperformance relative to the broader market over a three to five year time horizon. These companies form the core of the portfolio. The second principle applied in the stock selection process is intended to account for shorter-term factors including liquidity flows, economic data and government policy changes which, in the portfolio managers’ opinion, may have a significant impact on share prices within the region and result in an allocation to dynamic companies within the portfolio. This approach aims to mitigate any major style bias and deliver favorable risk-adjusted returns in different market conditions. The portfolio managers believe that both core and dynamic companies can be identified by conducting fundamental cash flow and returns analysis, detailed company research, and by engaging actively with investee companies.The Fund may lend portfolio securities on a short-term or long-term basis, in an amount equal to up to one-third of its total assets as determined at the time of the loan origination.
Risk [Heading]	rr_RiskHeading	<span style="color:#FFFFFF;font-family:Times New Roman;font-size:10.45pt;font-weight:bold;margin-left:0.0%;text-transform:uppercase;">Principal investment risks</span>
Risk Narrative [Text Block]	rr_RiskNarrativeTextBlock	The biggest risk is that the Fund’s returns will vary, and you could lose money. The Fund is designed for long-term investors seeking an Asian equity portfolio, including common stocks. Common stocks tend to be more volatile than many other investment choices. The principal risks associated with investing in the Fund are set forth below.Foreign Exposure Risk. The Fund normally has significant exposure to foreign markets as a result of its investments in foreign securities, including investments in emerging markets, which can be more volatile than the U.S. markets. As a result, its 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. The Fund’s investments in emerging market countries, if any, may involve risks greater than, or in addition to, the risks of investing in more developed countries.Emerging Markets Risk. The risks of foreign investing are heightened when investing in emerging markets. Emerging marketsecurities involve a number of additional 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. In addition, the Fund’s investments may be denominated in foreign currencies and therefore, changes in the value of a country’s currency compared to the U.S. dollar may affect the value of the Fund’s investments. To the extent that the Fund invests a significant portion of its assets in the securities of emerging markets issuers in or companies of a single country or region, it is more likely to be impacted by events or conditions affecting that country or region, which could have a negative impact on the Fund’s performance. 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 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 (“VIEs”), which subjects the Fund to the risks associated with the underlying Chinese issuer or operating company. As of September 30, 2021, approximately 85.4% of the Fund’s investments were in emerging markets (i.e., countries included in the MSCI Emerging Markets Indexsm).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.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.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.Market Risk. The value of the Fund’s portfolio may decrease if the value of an individual company or security, or multiple companies or securities, in the portfolio decreases or if the portfolio managers’ belief about a company’s intrinsic worth is incorrect. Further, regardless of how well individual companies or securities perform, the value of the Fund’s portfolio could also decrease if there are deteriorating economic or market conditions. 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. 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, social unrest, natural disasters, epidemics and pandemics, including COVID-19) adversely interrupt the global economy and financial markets.Portfolio Management Risk. The Fund is an actively managed investment portfolio and is therefore subject to the risk that the investment strategies employed for the Fund may fail to produce the intended results. The Fund may underperform its benchmark index or other mutual funds with similar investment objectives.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 in the Fund and may be susceptible to greater losses because of these developments.Growth Securities Risk. The Fund invests in companies that the portfolio managers believe have growth potential. Securities of companies perceived to be “growth” companies may be more volatile than other stocks and may involve special risks. If the portfolio managers’ 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 the market as a whole and other types of securities.Industry and Sector Risk. Although the Fund does not concentrate its investments in specific industries or industry sectors, it may have a significant portion of its assets invested in securities of companies conducting similar business, or business 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.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.Real Estate Securities Risk. The Fund’s performance may be affected by the risks associated with investments in real estate-related companies. The value of real estate-related companies’ securities is sensitive to changes in real estate values and rental income, property taxes, interest rates, tax and regulatory requirements, supply and demand, and the management skill and creditworthiness of the company. Investments in real estate investment trusts (“REITs”) involve the same risks as other real estate investments. REITs and REIT-like entities may have relatively small market capitalizations, which can increase the relative volatility of the market price for their securities. In addition, a REIT could fail to qualify for tax-free pass-through of its income under the Internal Revenue Code of 1986, as amended, or fail to maintain its exemption from registration under the Investment Company Act of 1940, as amended, which could produce adverse economic consequences for the REIT and its investors, including the Fund.Small- and Mid-Sized Companies Risk. The Fund’s 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. 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.Securities Lending Risk. The Fund may seek to earn additional income through lending its securities to certain qualified broker-dealers and institutions. There is the risk that when portfolio securities are lent, the securities may not be returned on a timely basis, and the Fund may experience delays and costs in recovering the security or gaining access to the collateral provided to the Fund to collateralize the loan. If the Fund is unable to recover a security on loan, the Fund may use the collateral to purchase replacement securities in the market. There is a risk that the value of the collateral could decrease below the cost of the replacement security by the time the replacement investment is made, resulting in a loss to the Fund.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.
Risk Lose Money [Text]	rr_RiskLoseMoney	<span style="font-family:Times New Roman;font-size:9.50pt;">The biggest risk is that the Fund’s returns will vary, and you could lose money.</span>
Risk Not Insured Depository Institution [Text]	rr_RiskNotInsuredDepositoryInstitution	<span style="color:#000000;font-family:Times New Roman;font-size:9.50pt;font-style:italic;">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.</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:0.0%;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, as well as to one or more supplemental indices that have investment characteristics similar to those of the Fund. 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="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>
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 the periods indicated to a broad-based securities market index, as well as to one or more supplemental indices that have investment characteristics similar to those of the Fund. 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 12/31/21)
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="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 Fund also compares its performance to the MSCI All Country Asia-Pacific ex-Japan Index. The MSCI All Country Asia ex-Japan Index is used to calculate the Fund’s performance fee adjustment. The indices are described below.•The MSCI All Country Asia ex-Japan Index is designed to measure the equity market performance of Asia, excluding Japan.•The MSCI All Country Asia-Pacific ex-Japan Index captures large and mid cap representation across developed market countries and emerging market countries in the Asia-Pacific region, 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 | Class D
Risk Return Abstract	rr_RiskReturnAbstract
Management Fees	rr_ManagementFeesOverAssets	0.92%	[1]
Other Expenses	rr_OtherExpensesOverAssets	0.77%
Total Annual Fund Operating Expenses	rr_ExpensesOverAssets	1.69%
Fee Waiver	rr_FeeWaiverOrReimbursementOverAssets	0.55%	[2]
Total Annual Fund Operating Expenses After Fee Waiver	rr_NetExpensesOverAssets	1.14%	[2]
1 Year	rr_ExpenseExampleYear01	$ 172
3 Years	rr_ExpenseExampleYear03	533
5 Years	rr_ExpenseExampleYear05	918
10 Years	rr_ExpenseExampleYear10	$ 1,998
2012	rr_AnnualReturn2012	28.43%
2013	rr_AnnualReturn2013	(1.56%)
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%)
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	(11.15%)
5 Years	rr_AverageAnnualReturnYear05	10.23%
10 Years	rr_AverageAnnualReturnYear10	8.16%
Since Inception	rr_AverageAnnualReturnSinceInception	5.34%
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	(11.70%)
5 Years	rr_AverageAnnualReturnYear05	9.54%
10 Years	rr_AverageAnnualReturnYear10	7.42%
Since Inception	rr_AverageAnnualReturnSinceInception	4.65%
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	(6.39%)	[3]
5 Years	rr_AverageAnnualReturnYear05	8.05%	[3]
10 Years	rr_AverageAnnualReturnYear10	6.52%	[3]
Since Inception	rr_AverageAnnualReturnSinceInception	4.15%	[3]
Inception Date	rr_AverageAnnualReturnInceptionDate	Jul. 29, 2011	[3]
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	(4.72%)
5 Years	rr_AverageAnnualReturnYear05	11.30%
10 Years	rr_AverageAnnualReturnYear10	8.02%
Since Inception	rr_AverageAnnualReturnSinceInception	5.50%
Class D Shares | Janus Henderson Asia Equity Fund | MSCI All Country Asia-Pacific ex-Japan Index (reflects no deduction for expenses, fees, or taxes, except foreign withholding taxes)
Risk Return Abstract	rr_RiskReturnAbstract
1 Year	rr_AverageAnnualReturnYear01	(2.90%)
5 Years	rr_AverageAnnualReturnYear05	10.81%
10 Years	rr_AverageAnnualReturnYear10	7.71%
Since Inception	rr_AverageAnnualReturnSinceInception	5.43%

[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] 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), administrative services fees, brokerage commissions, interest, dividends, taxes, acquired fund fees and expenses, and extraordinary expenses) exceed 0.99% for at least a one-year period commencing on January 28, 2022. The contractual waiver may be terminated or modified prior to this date only at the discretion of the Board of Trustees.

[3] 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.