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 Global Technology and Innovation Fund
Risk Return Abstract	rr_RiskReturnAbstract
Risk/Return [Heading]	rr_RiskReturnHeading	<span style="color:#000000;font-family:Times New Roman;font-size:15.20pt;font-weight:bold;margin-left:3pt;">Janus Henderson Global Technology and Innovation Fund</span>
Objective [Heading]	rr_ObjectiveHeading	<span style="color:#FFFFFF;font-family:Times New Roman;font-size:10.45pt;font-weight:bold;margin-left:0.0pt;text-transform:uppercase;">Investment Objective</span>
Objective, Primary [Text Block]	rr_ObjectivePrimaryTextBlock	Janus Henderson Global Technology and Innovation 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)
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 43% of the average value of its portfolio.
Portfolio Turnover, Rate	rr_PortfolioTurnoverRate	43.00%
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="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 and reinvest all dividends </span><span style="color:#000000;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 remain the same. Class C Shares automatically convert to Class A Shares 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 securities of companies that portfolio management believes will benefit significantly from advances or improvements in technology. These companies generally fall into two categories:•companies that portfolio management believes have or will develop products, processes, or services that will provide significant technological advancements or improvements; and•companies that portfolio management believes rely extensively on technology in connection with their operations or services.Some of the industries and companies likely to be represented in the Fund’s portfolio include e-commerce (companies doing business through the Internet); computer (hardware and software); communications (voice, data, and wireless); industrials; Internet (software, services, and infrastructure equipment); and media and entertainment.The Fund implements this policy by investing primarily in equity securities of U.S. and foreign companies selected for their growth potential. The Fund typically invests at least 40% of its net assets in securities of issuers or companies that are economically tied to different countries throughout the world, excluding the United States. An issuer is deemed to be economically tied to a country or countries outside of the United States if one or more of the following tests are met: (i) the issuer is organized in, or its primary business office or principal trading market of its equity is located in, a country outside of the United States; (ii) a majority of the issuer’s revenues are derived from outside of the United States; or (iii) a majority of the issuer’s assets are located outside of the United States. The Fund may have exposure to emerging markets. From time to time, the Fund may invest in shares of companies through initial public offerings.Portfolio management applies a “bottom up” approach in choosing investments. In other words, portfolio management looksat companies one at a time to determine if a company is an attractive investment opportunity and if it is consistent with the Fund’s investment policies. Factors that portfolio management may consider in their fundamental analysis include the strength of a company’s balance sheet and a company’s projected returns or growth rates. Portfolio management will generally consider selling a position when, among other things, the investment thesis for owning a position has changed or if the position exceeds its targeted value.The Fund may seek to earn additional income through lending its securities to certain qualified broker-dealers and institutions 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:0.0pt;text-transform:uppercase;">Principal investment risks</span>
Bar Chart and Performance Table [Heading]	rr_BarChartAndPerformanceTableHeading	<span style="color:#FFFFFF;font-family:Times New Roman;font-size:10.45pt;font-weight:bold;margin-left:0.0pt;text-transform:uppercase;">Performance information</span>
Performance Narrative [Text Block]	rr_PerformanceNarrativeTextBlock	The following information provides some indication of the risks of investing in the Fund by showing how the Fund’s performance has varied over time. Class T Shares (formerly named Class J Shares, the initial share class) of the Fund commenced operations with the Fund’s inception. Class A Shares, Class C Shares, Class S Shares, and Class I Shares of the Fund commenced operations on July 6, 2009. Class N Shares of the Fund commenced operations on January 27, 2017.•The performance shown for Class T Shares is calculated using the fees and expenses of Class T Shares in effect during the periods shown, net of any applicable fee and expense limitations or waivers.•The performance shown for Class A Shares, Class C Shares, and Class S Shares for periods prior to July 6, 2009, reflects the performance of the Fund’s former Class J Shares, calculated using the fees and expenses of each respective share class, without the effect of any fee and expense limitations or waivers.•The performance shown for Class I Shares for periods prior to July 6, 2009, reflects the performance of the Fund’s former Class J Shares, calculated using the fees and expenses of Class J Shares, net of any applicable fee and expense limitations or waivers.•The performance shown for Class N Shares for periods prior to January 27, 2017, reflects the performance of the Fund’s Class T Shares, calculated using the fees and expenses of Class T Shares, net of any applicable fee and expense limitations or waivers.If Class A Shares, Class C Shares, Class S Shares, and Class I Shares of the Fund had been available during periods prior to July 6, 2009, or Class N Shares of the Fund had been available during periods prior to January 27, 2017, the performance shown for each respective share class may have been different. The performance shown for the periods following the Fund’s commencement of Class A Shares, Class C Shares, Class S Shares, Class I Shares, and Class N Shares reflects the fees and expenses of each respective share class, net of any applicable fee and expense limitations or waivers.The bar chart depicts the change in performance from year to year during the periods indicated. The bar chart figures do not include any applicable sales charges that an investor may pay when they buy or sell Class A Shares or Class C Shares of the Fund. If sales charges were included, the returns would be lower.The table compares the Fund’s average annual returns for the periods indicated to a broad-based securities market index, 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 atjanushenderson.com/performance or by calling 1-877-335-2687.
Performance Information Illustrates Variability of Returns [Text]	rr_PerformanceInformationIllustratesVariabilityOfReturns	<span style="color:#000000;font-family:Times New Roman;font-size:9.50pt;">The bar chart depicts the change in performance from year to year during the periods indicated. </span><span style="color:#000000;font-family:Times New Roman;font-size:9.50pt;">The bar chart figures do not </span><span style="color:#000000;font-family:Times New Roman;font-size:9.50pt;">include any applicable sales charges that an investor may pay when they buy or sell Class A Shares or Class C Shares of the Fund. If sales charges were included, the returns would be lower.</span><span style="color:#000000;font-family:Times New Roman;font-size:9.50pt;">The table compares the Fund’s average annual returns for </span><span style="color:#000000;font-family:Times New Roman;font-size:9.50pt;">the periods indicated to a broad-based securities market index, 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 Additional Market Index [Text]	rr_PerformanceAdditionalMarketIndex	<span style="color:#000000;font-family:Times New Roman;font-size:9.50pt;">The table compares the Fund’s average annual returns for </span><span style="color:#000000;font-family:Times New Roman;font-size:9.50pt;">the periods indicated to a broad-based securities market index, 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;">1-877-335-2687</span>
Performance Availability Website Address [Text]	rr_PerformanceAvailabilityWebSiteAddress	<span style="color:#000000;font-family:Times New Roman;font-size:9.50pt;font-style:italic;">janushenderson.com/performance</span>
Performance Past Does Not Indicate Future [Text]	rr_PerformancePastDoesNotIndicateFuture	<span style="color:#000000;font-family:Times New Roman;font-size:9.50pt;font-style:italic;">The Fund’s past performance (before and after taxes) does not necessarily indicate how it will perform in the future.</span>
Bar Chart [Heading]	rr_BarChartHeading	Annual Total Returns for Class T Shares (calendar year-end)
Bar Chart Does Not Reflect Sales Loads [Text]	rr_BarChartDoesNotReflectSalesLoads	<span style="color:#000000;font-family:Times New Roman;font-size:9.50pt;">The bar chart figures do not </span><span style="color:#000000;font-family:Times New Roman;font-size:9.50pt;">include any applicable sales charges that an investor may pay when they buy or sell Class A Shares or Class C Shares of the Fund. If sales charges were included, the returns would be lower.</span>
Bar Chart Closing [Text Block]	rr_BarChartClosingTextBlock	Best Quarter:2nd Quarter 202032.49%Worst Quarter:2nd Quarter 2022– 26.50%
Performance Table Heading	rr_PerformanceTableHeading	Average Annual Total Returns (periods ended 12/31/23)
Performance Table Does Reflect Sales Loads	rr_PerformanceTableDoesReflectSalesLoads	<span style="color:#000000;font-family:Times New Roman;font-size:7.60pt;">The one year return is calculated to include the contingent deferred sales charge.</span>
Performance Table Uses Highest Federal Rate	rr_PerformanceTableUsesHighestFederalRate	<span style="color:#000000;font-family:Times New Roman;font-size:9.50pt;">After-tax returns are calculated using the historically highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes. </span>
Performance Table Not Relevant to Tax Deferred	rr_PerformanceTableNotRelevantToTaxDeferred	<span style="color:#000000;font-family:Times New Roman;font-size:9.50pt;">Actual after-tax returns depend on your individual tax situation and may differ </span><span style="color:#000000;font-family:Times New Roman;font-size:9.50pt;">from those shown in the preceding table. The after-tax return information shown above does not apply to Fund shares held through a tax-advantaged account, such as a 401(k) plan or an IRA.</span>
Performance Table One Class of after Tax Shown [Text]	rr_PerformanceTableOneClassOfAfterTaxShown	<span style="color:#000000;font-family:Times New Roman;font-size:9.50pt;">After-tax returns are only shown for Class T Shares of the Fund. After-tax returns for the other classes of Shares will vary from those shown for Class T Shares due to varying sales charges (as applicable), fees, and expenses among the classes.</span>
Performance Table Narrative	rr_PerformanceTableNarrativeTextBlock	The Fund’s primary benchmark index is the S&P 500 Index. The Fund also compares its performance to the MSCI All Country World Information Technology Index. The indices are described below.•The S&P 500 Index is a commonly recognized, market capitalization-weighted index of 500 widely held equity securities, designed to measure broad U.S. equity performance.•The MSCI All Country World Information Technology Index is a capitalization-weighted index that measures the performance of information technology securities from developed market countries and emerging market countries.After-tax returns are calculated using distributions for the Fund’s Class T Shares (formerly named Class J Shares, the initial share class). After-tax returns are calculated using the historically highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes. Actual after-tax returns depend on your individual tax situation and may differ from those shown in the preceding table. The after-tax return information shown above does not apply to Fund shares held through a tax-advantaged account, such as a 401(k) plan or an IRA.After-tax returns are only shown for Class T Shares of the Fund. After-tax returns for the other classes of Shares will vary from those shown for Class T Shares due to varying sales charges (as applicable), fees, and expenses among the classes.
Performance Table Closing [Text Block]	rr_PerformanceTableClosingTextBlock	Updated performance information is available atjanushenderson.com/performance or by calling 1-877-335-2687.
Class A C S I N T Shares | Janus Henderson Global Technology and Innovation 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 Global Technology and Innovation 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 Global Technology and Innovation 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 Global Technology and Innovation 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 Global Technology and Innovation Fund | Mid-Sized Companies Risk [Member]
Risk Return Abstract	rr_RiskReturnAbstract
Risk [Text Block]	rr_RiskTextBlock	Mid-Sized Companies Risk. Investments in securities issued by mid-sized companies may involve greater risks than are customarily associated with larger, more established companies. For example, 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 mid-sized companies tend to be more volatile 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 Global Technology and Innovation Fund | Industry and Sector Risk [Member]
Risk Return Abstract	rr_RiskReturnAbstract
Risk [Text Block]	rr_RiskTextBlock	Industry and Sector Risk. The Fund may have a significant portion of its assets invested in securities of companies conducting similar business or businesses within the same economic sector. 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 Global Technology and Innovation Fund | Technology Industry Risk [Member]
Risk Return Abstract	rr_RiskReturnAbstract
Risk [Text Block]	rr_RiskTextBlock	•Technology Sector Risk. In the technology sector, competitive pressures may have a significant effect on the performance of companies in which the Fund may invest. In addition, technology and technology-related companies often progress at an accelerated rate, and these companies may be subject to short product cycles and aggressive pricing, which may increase their volatility.
Class A C S I N T Shares | Janus Henderson Global Technology and Innovation 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 Global Technology and Innovation 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 Global Technology and Innovation Fund | Initial Public Offering Risk [Member]
Risk Return Abstract	rr_RiskReturnAbstract
Risk [Text Block]	rr_RiskTextBlock	Initial Public Offering Risk. The Fund’s purchase of shares issued in an initial public offering (“IPO”) exposes it to the risks associated with companies that have little operating history as public companies, as well as to the risks inherent in those sectors of the market where these new issuers operate. There can be no assurance that the Fund will identify favorable IPO investment opportunities.
Class A C S I N T Shares | Janus Henderson Global Technology and Innovation 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. 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.
Class A C S I N T Shares | Janus Henderson Global Technology and Innovation Fund | Securities Lending Risk [Member]
Risk Return Abstract	rr_RiskReturnAbstract
Risk [Text Block]	rr_RiskTextBlock	Securities Lending Risk. 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.
Class A C S I N T Shares | Janus Henderson Global Technology and Innovation Fund | Class A
Risk Return Abstract	rr_RiskReturnAbstract
Maximum Sales Charge (load) Imposed on Purchases (as a percentage of offering price)	rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice	5.75%
Maximum Deferred Sales Charge (load) (as a percentage of the lower of original purchase price or redemption proceeds)	rr_MaximumDeferredSalesChargeOverOther	none
Management Fees	rr_ManagementFeesOverAssets	0.64%
Distribution/Service (12b-1) Fees	rr_DistributionAndService12b1FeesOverAssets	0.25%
Other Expenses	rr_OtherExpensesOverAssets	0.11%
Total Annual Fund Operating Expenses	rr_ExpensesOverAssets	1.00%
1 Year	rr_ExpenseExampleYear01	$ 671
3 Years	rr_ExpenseExampleYear03	875
5 Years	rr_ExpenseExampleYear05	1,096
10 Years	rr_ExpenseExampleYear10	1,729
1 Year	rr_ExpenseExampleNoRedemptionYear01	671
3 Years	rr_ExpenseExampleNoRedemptionYear03	875
5 Years	rr_ExpenseExampleNoRedemptionYear05	1,096
10 Years	rr_ExpenseExampleNoRedemptionYear10	$ 1,729
Class A C S I N T Shares | Janus Henderson Global Technology and Innovation Fund | Class C
Risk Return Abstract	rr_RiskReturnAbstract
Maximum Sales Charge (load) Imposed on Purchases (as a percentage of offering price)	rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice	none
Maximum Deferred Sales Charge (load) (as a percentage of the lower of original purchase price or redemption proceeds)	rr_MaximumDeferredSalesChargeOverOther	1.00%
Management Fees	rr_ManagementFeesOverAssets	0.64%
Distribution/Service (12b-1) Fees	rr_DistributionAndService12b1FeesOverAssets	1.00%
Other Expenses	rr_OtherExpensesOverAssets	0.12%
Total Annual Fund Operating Expenses	rr_ExpensesOverAssets	1.76%
1 Year	rr_ExpenseExampleYear01	$ 279
3 Years	rr_ExpenseExampleYear03	554
5 Years	rr_ExpenseExampleYear05	954
10 Years	rr_ExpenseExampleYear10	1,873
1 Year	rr_ExpenseExampleNoRedemptionYear01	179
3 Years	rr_ExpenseExampleNoRedemptionYear03	554
5 Years	rr_ExpenseExampleNoRedemptionYear05	954
10 Years	rr_ExpenseExampleNoRedemptionYear10	$ 1,873
Class A C S I N T Shares | Janus Henderson Global Technology and Innovation Fund | Class S
Risk Return Abstract	rr_RiskReturnAbstract
Maximum Sales Charge (load) Imposed on Purchases (as a percentage of offering price)	rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice	none
Maximum Deferred Sales Charge (load) (as a percentage of the lower of original purchase price or redemption proceeds)	rr_MaximumDeferredSalesChargeOverOther	none
Management Fees	rr_ManagementFeesOverAssets	0.64%
Distribution/Service (12b-1) Fees	rr_DistributionAndService12b1FeesOverAssets	0.25%
Other Expenses	rr_OtherExpensesOverAssets	0.29%
Total Annual Fund Operating Expenses	rr_ExpensesOverAssets	1.18%
1 Year	rr_ExpenseExampleYear01	$ 120
3 Years	rr_ExpenseExampleYear03	375
5 Years	rr_ExpenseExampleYear05	649
10 Years	rr_ExpenseExampleYear10	1,432
1 Year	rr_ExpenseExampleNoRedemptionYear01	120
3 Years	rr_ExpenseExampleNoRedemptionYear03	375
5 Years	rr_ExpenseExampleNoRedemptionYear05	649
10 Years	rr_ExpenseExampleNoRedemptionYear10	$ 1,432
Class A C S I N T Shares | Janus Henderson Global Technology and Innovation Fund | Class I
Risk Return Abstract	rr_RiskReturnAbstract
Maximum Sales Charge (load) Imposed on Purchases (as a percentage of offering price)	rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice	none
Maximum Deferred Sales Charge (load) (as a percentage of the lower of original purchase price or redemption proceeds)	rr_MaximumDeferredSalesChargeOverOther	none
Management Fees	rr_ManagementFeesOverAssets	0.64%
Distribution/Service (12b-1) Fees	rr_DistributionAndService12b1FeesOverAssets	none
Other Expenses	rr_OtherExpensesOverAssets	0.12%
Total Annual Fund Operating Expenses	rr_ExpensesOverAssets	0.76%
1 Year	rr_ExpenseExampleYear01	$ 78
3 Years	rr_ExpenseExampleYear03	243
5 Years	rr_ExpenseExampleYear05	422
10 Years	rr_ExpenseExampleYear10	942
1 Year	rr_ExpenseExampleNoRedemptionYear01	78
3 Years	rr_ExpenseExampleNoRedemptionYear03	243
5 Years	rr_ExpenseExampleNoRedemptionYear05	422
10 Years	rr_ExpenseExampleNoRedemptionYear10	$ 942
Class A C S I N T Shares | Janus Henderson Global Technology and Innovation Fund | Class N
Risk Return Abstract	rr_RiskReturnAbstract
Maximum Sales Charge (load) Imposed on Purchases (as a percentage of offering price)	rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice	none
Maximum Deferred Sales Charge (load) (as a percentage of the lower of original purchase price or redemption proceeds)	rr_MaximumDeferredSalesChargeOverOther	none
Management Fees	rr_ManagementFeesOverAssets	0.64%
Distribution/Service (12b-1) Fees	rr_DistributionAndService12b1FeesOverAssets	none
Other Expenses	rr_OtherExpensesOverAssets	0.03%
Total Annual Fund Operating Expenses	rr_ExpensesOverAssets	0.67%
1 Year	rr_ExpenseExampleYear01	$ 68
3 Years	rr_ExpenseExampleYear03	214
5 Years	rr_ExpenseExampleYear05	373
10 Years	rr_ExpenseExampleYear10	835
1 Year	rr_ExpenseExampleNoRedemptionYear01	68
3 Years	rr_ExpenseExampleNoRedemptionYear03	214
5 Years	rr_ExpenseExampleNoRedemptionYear05	373
10 Years	rr_ExpenseExampleNoRedemptionYear10	$ 835
Class A C S I N T Shares | Janus Henderson Global Technology and Innovation Fund | Class T
Risk Return Abstract	rr_RiskReturnAbstract
Maximum Sales Charge (load) Imposed on Purchases (as a percentage of offering price)	rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice	none
Maximum Deferred Sales Charge (load) (as a percentage of the lower of original purchase price or redemption proceeds)	rr_MaximumDeferredSalesChargeOverOther	none
Management Fees	rr_ManagementFeesOverAssets	0.64%
Distribution/Service (12b-1) Fees	rr_DistributionAndService12b1FeesOverAssets	none
Other Expenses	rr_OtherExpensesOverAssets	0.28%
Total Annual Fund Operating Expenses	rr_ExpensesOverAssets	0.92%
1 Year	rr_ExpenseExampleYear01	$ 94
3 Years	rr_ExpenseExampleYear03	293
5 Years	rr_ExpenseExampleYear05	509
10 Years	rr_ExpenseExampleYear10	1,131
1 Year	rr_ExpenseExampleNoRedemptionYear01	94
3 Years	rr_ExpenseExampleNoRedemptionYear03	293
5 Years	rr_ExpenseExampleNoRedemptionYear05	509
10 Years	rr_ExpenseExampleNoRedemptionYear10	$ 1,131
2014	rr_AnnualReturn2014	9.27%
2015	rr_AnnualReturn2015	4.49%
2016	rr_AnnualReturn2016	13.71%
2017	rr_AnnualReturn2017	44.65%
2018	rr_AnnualReturn2018	0.73%
2019	rr_AnnualReturn2019	45.06%
2020	rr_AnnualReturn2020	50.89%
2021	rr_AnnualReturn2021	17.61%
2022	rr_AnnualReturn2022	(37.69%)
2023	rr_AnnualReturn2023	55.14%
Highest Quarterly Return, Label	rr_HighestQuarterlyReturnLabel	Best Quarter
Highest Quarterly Return, Date	rr_BarChartHighestQuarterlyReturnDate	Jun. 30, 2020
Highest Quarterly Return	rr_BarChartHighestQuarterlyReturn	32.49%
Lowest Quarterly Return, Label	rr_LowestQuarterlyReturnLabel	Worst Quarter
Lowest Quarterly Return, Date	rr_BarChartLowestQuarterlyReturnDate	Jun. 30, 2022
Lowest Quarterly Return	rr_BarChartLowestQuarterlyReturn	(26.50%)
Class A C S I N T Shares | Janus Henderson Global Technology and Innovation Fund | Return Before Taxes | Class A
Risk Return Abstract	rr_RiskReturnAbstract
1 Year	rr_AverageAnnualReturnYear01	46.07%	[1]
5 Years	rr_AverageAnnualReturnYear05	18.48%	[1]
10 Years	rr_AverageAnnualReturnYear10	15.94%	[1]
Since Inception	rr_AverageAnnualReturnSinceInception	10.18%	[1]
Inception Date	rr_AverageAnnualReturnInceptionDate	Dec. 31, 1998	[1]
Class A C S I N T Shares | Janus Henderson Global Technology and Innovation Fund | Return Before Taxes | Class C
Risk Return Abstract	rr_RiskReturnAbstract
1 Year	rr_AverageAnnualReturnYear01	52.87%	[2]
5 Years	rr_AverageAnnualReturnYear05	19.10%	[2]
10 Years	rr_AverageAnnualReturnYear10	15.84%	[2]
Since Inception	rr_AverageAnnualReturnSinceInception	9.67%	[2]
Inception Date	rr_AverageAnnualReturnInceptionDate	Dec. 31, 1998	[2]
Class A C S I N T Shares | Janus Henderson Global Technology and Innovation Fund | Return Before Taxes | Class S
Risk Return Abstract	rr_RiskReturnAbstract
1 Year	rr_AverageAnnualReturnYear01	54.74%
5 Years	rr_AverageAnnualReturnYear05	19.67%
10 Years	rr_AverageAnnualReturnYear10	16.45%
Since Inception	rr_AverageAnnualReturnSinceInception	10.29%
Inception Date	rr_AverageAnnualReturnInceptionDate	Dec. 31, 1998
Class A C S I N T Shares | Janus Henderson Global Technology and Innovation Fund | Return Before Taxes | Class I
Risk Return Abstract	rr_RiskReturnAbstract
1 Year	rr_AverageAnnualReturnYear01	55.36%
5 Years	rr_AverageAnnualReturnYear05	20.18%
10 Years	rr_AverageAnnualReturnYear10	16.93%
Since Inception	rr_AverageAnnualReturnSinceInception	10.68%
Inception Date	rr_AverageAnnualReturnInceptionDate	Dec. 31, 1998
Class A C S I N T Shares | Janus Henderson Global Technology and Innovation Fund | Return Before Taxes | Class N
Risk Return Abstract	rr_RiskReturnAbstract
1 Year	rr_AverageAnnualReturnYear01	55.50%
5 Years	rr_AverageAnnualReturnYear05	20.28%
10 Years	rr_AverageAnnualReturnYear10	16.95%
Since Inception	rr_AverageAnnualReturnSinceInception	10.66%
Inception Date	rr_AverageAnnualReturnInceptionDate	Dec. 31, 1998
Class A C S I N T Shares | Janus Henderson Global Technology and Innovation Fund | Return Before Taxes | Class T
Risk Return Abstract	rr_RiskReturnAbstract
1 Year	rr_AverageAnnualReturnYear01	55.14%
5 Years	rr_AverageAnnualReturnYear05	20.00%
10 Years	rr_AverageAnnualReturnYear10	16.76%
Since Inception	rr_AverageAnnualReturnSinceInception	10.58%
Inception Date	rr_AverageAnnualReturnInceptionDate	Dec. 31, 1998
Class A C S I N T Shares | Janus Henderson Global Technology and Innovation Fund | Return After Taxes on Distributions | Class T
Risk Return Abstract	rr_RiskReturnAbstract
1 Year	rr_AverageAnnualReturnYear01	54.84%
5 Years	rr_AverageAnnualReturnYear05	18.17%
10 Years	rr_AverageAnnualReturnYear10	14.67%
Since Inception	rr_AverageAnnualReturnSinceInception	9.67%
Inception Date	rr_AverageAnnualReturnInceptionDate	Dec. 31, 1998
Class A C S I N T Shares | Janus Henderson Global Technology and Innovation Fund | Return After Taxes on Distributions and Sale of Fund Shares | Class T
Risk Return Abstract	rr_RiskReturnAbstract
1 Year	rr_AverageAnnualReturnYear01	32.84%
5 Years	rr_AverageAnnualReturnYear05	16.12%
10 Years	rr_AverageAnnualReturnYear10	13.44%
Since Inception	rr_AverageAnnualReturnSinceInception	9.03%
Inception Date	rr_AverageAnnualReturnInceptionDate	Dec. 31, 1998
Class A C S I N T Shares | Janus Henderson Global Technology and Innovation Fund | S&P 500® Index (reflects no deduction for expenses, fees, or taxes) | Class A
Risk Return Abstract	rr_RiskReturnAbstract
1 Year	rr_AverageAnnualReturnYear01	26.29%
5 Years	rr_AverageAnnualReturnYear05	15.69%
10 Years	rr_AverageAnnualReturnYear10	12.03%
Since Inception	rr_AverageAnnualReturnSinceInception	7.56%
Class A C S I N T Shares | Janus Henderson Global Technology and Innovation Fund | S&P 500® Index (reflects no deduction for expenses, fees, or taxes) | Class C
Risk Return Abstract	rr_RiskReturnAbstract
1 Year	rr_AverageAnnualReturnYear01	26.29%
5 Years	rr_AverageAnnualReturnYear05	15.69%
10 Years	rr_AverageAnnualReturnYear10	12.03%
Since Inception	rr_AverageAnnualReturnSinceInception	7.56%
Class A C S I N T Shares | Janus Henderson Global Technology and Innovation Fund | S&P 500® Index (reflects no deduction for expenses, fees, or taxes) | Class S
Risk Return Abstract	rr_RiskReturnAbstract
1 Year	rr_AverageAnnualReturnYear01	26.29%
5 Years	rr_AverageAnnualReturnYear05	15.69%
10 Years	rr_AverageAnnualReturnYear10	12.03%
Since Inception	rr_AverageAnnualReturnSinceInception	7.56%
Class A C S I N T Shares | Janus Henderson Global Technology and Innovation Fund | S&P 500® Index (reflects no deduction for expenses, fees, or taxes) | Class I
Risk Return Abstract	rr_RiskReturnAbstract
1 Year	rr_AverageAnnualReturnYear01	26.29%
5 Years	rr_AverageAnnualReturnYear05	15.69%
10 Years	rr_AverageAnnualReturnYear10	12.03%
Since Inception	rr_AverageAnnualReturnSinceInception	7.56%
Class A C S I N T Shares | Janus Henderson Global Technology and Innovation Fund | S&P 500® Index (reflects no deduction for expenses, fees, or taxes) | Class N
Risk Return Abstract	rr_RiskReturnAbstract
1 Year	rr_AverageAnnualReturnYear01	26.29%
5 Years	rr_AverageAnnualReturnYear05	15.69%
10 Years	rr_AverageAnnualReturnYear10	12.03%
Since Inception	rr_AverageAnnualReturnSinceInception	7.56%
Class A C S I N T Shares | Janus Henderson Global Technology and Innovation Fund | S&P 500® Index (reflects no deduction for expenses, fees, or taxes) | Class T
Risk Return Abstract	rr_RiskReturnAbstract
1 Year	rr_AverageAnnualReturnYear01	26.29%
5 Years	rr_AverageAnnualReturnYear05	15.69%
10 Years	rr_AverageAnnualReturnYear10	12.03%
Since Inception	rr_AverageAnnualReturnSinceInception	7.56%
Class A C S I N T Shares | Janus Henderson Global Technology and Innovation Fund | MSCI All Country World Information Technology Index (reflects no deduction for expenses, fees, or taxes, except foreign withholding taxes) | Class A
Risk Return Abstract	rr_RiskReturnAbstract
1 Year	rr_AverageAnnualReturnYear01	51.02%
5 Years	rr_AverageAnnualReturnYear05	23.18%
10 Years	rr_AverageAnnualReturnYear10	17.58%
Since Inception	rr_AverageAnnualReturnSinceInception	8.26%
Class A C S I N T Shares | Janus Henderson Global Technology and Innovation Fund | MSCI All Country World Information Technology Index (reflects no deduction for expenses, fees, or taxes, except foreign withholding taxes) | Class C
Risk Return Abstract	rr_RiskReturnAbstract
1 Year	rr_AverageAnnualReturnYear01	51.02%
5 Years	rr_AverageAnnualReturnYear05	23.18%
10 Years	rr_AverageAnnualReturnYear10	17.58%
Since Inception	rr_AverageAnnualReturnSinceInception	8.26%
Inception Date	rr_AverageAnnualReturnInceptionDate
Class A C S I N T Shares | Janus Henderson Global Technology and Innovation Fund | MSCI All Country World Information Technology Index (reflects no deduction for expenses, fees, or taxes, except foreign withholding taxes) | Class S
Risk Return Abstract	rr_RiskReturnAbstract
1 Year	rr_AverageAnnualReturnYear01	51.02%
5 Years	rr_AverageAnnualReturnYear05	23.18%
10 Years	rr_AverageAnnualReturnYear10	17.58%
Since Inception	rr_AverageAnnualReturnSinceInception	8.26%
Class A C S I N T Shares | Janus Henderson Global Technology and Innovation Fund | MSCI All Country World Information Technology Index (reflects no deduction for expenses, fees, or taxes, except foreign withholding taxes) | Class I
Risk Return Abstract	rr_RiskReturnAbstract
1 Year	rr_AverageAnnualReturnYear01	51.02%
5 Years	rr_AverageAnnualReturnYear05	23.18%
10 Years	rr_AverageAnnualReturnYear10	17.58%
Since Inception	rr_AverageAnnualReturnSinceInception	8.26%
Class A C S I N T Shares | Janus Henderson Global Technology and Innovation Fund | MSCI All Country World Information Technology Index (reflects no deduction for expenses, fees, or taxes, except foreign withholding taxes) | Class N
Risk Return Abstract	rr_RiskReturnAbstract
1 Year	rr_AverageAnnualReturnYear01	51.02%
5 Years	rr_AverageAnnualReturnYear05	23.18%
10 Years	rr_AverageAnnualReturnYear10	17.58%
Since Inception	rr_AverageAnnualReturnSinceInception	8.26%
Class A C S I N T Shares | Janus Henderson Global Technology and Innovation Fund | MSCI All Country World Information Technology Index (reflects no deduction for expenses, fees, or taxes, except foreign withholding taxes) | Class T
Risk Return Abstract	rr_RiskReturnAbstract
1 Year	rr_AverageAnnualReturnYear01	51.02%
5 Years	rr_AverageAnnualReturnYear05	23.18%
10 Years	rr_AverageAnnualReturnYear10	17.58%
Since Inception	rr_AverageAnnualReturnSinceInception	8.26%

[1] Calculated assuming maximum permitted sales loads.

[2] The one year return is calculated to include the contingent deferred sales charge.