Label	Element	Value
Risk/Return:	rr_RiskReturnAbstract
Registrant Name	dei_EntityRegistrantName	JANUS INVESTMENT FUND
Prospectus Date	rr_ProspectusDate	Oct. 29, 2018
Janus Henderson Value Plus Income Fund | Class A, C, S, I, N, T Shares
Risk/Return:	rr_RiskReturnAbstract
Risk/Return [Heading]	rr_RiskReturnHeading	<b>FUND SUMMARY<br/><br/>Janus Henderson Value Plus Income Fund</b>
Objective [Heading]	rr_ObjectiveHeading	<b>INVESTMENT OBJECTIVE</b>
Objective, Primary [Text Block]	rr_ObjectivePrimaryTextBlock	Janus Henderson Value Plus Income Fund seeks capital appreciation and current income.
Expense [Heading]	rr_ExpenseHeading	<b>FEES AND EXPENSES OF THE FUND</b>
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. Each share class has different expenses, but represents an investment in the same Fund.
Shareholder Fees Caption [Text]	rr_ShareholderFeesCaption	<b>SHAREHOLDER FEES</b><br/>(fees paid directly from your investment)
Operating Expenses Caption [Text]	rr_OperatingExpensesCaption	<b>ANNUAL FUND OPERATING EXPENSES</b><br/>(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	November 1, 2019
Portfolio Turnover [Heading]	rr_PortfolioTurnoverHeading	<b>Portfolio Turnover:</b>
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 100% of the average value of its portfolio.
Portfolio Turnover, Rate	rr_PortfolioTurnoverRate	100.00%
Expense Breakpoint Discounts [Text]	rr_ExpenseBreakpointDiscounts	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 mutual 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 74 of the Fund’s Prospectus and in the “Purchases” section on page 82 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 N Shares of the Fund that are not reflected in the table or in the example below.
Expense Breakpoint, Minimum Investment Required [Amount]	rr_ExpenseBreakpointMinimumInvestmentRequiredAmount	$ 50,000
Expense Example [Heading]	rr_ExpenseExampleHeading	<b>EXAMPLE:</b>
Expense Example by Year [Heading]	rr_ExpenseExampleByYearHeading	The Example assumes that you invest $10,000 in the Fund for the time periods indicated and reinvest all dividends and distributions. 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:
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.
Expense Example by, Year, Caption [Text]	rr_ExpenseExampleByYearCaption	<b>If Shares are redeemed:</b>
Expense Example, No Redemption, By Year, Caption [Text]	rr_ExpenseExampleNoRedemptionByYearCaption	<b>If Shares are not redeemed:</b>
Strategy [Heading]	rr_StrategyHeading	<b>PRINCIPAL INVESTMENT STRATEGIES</b>
Strategy Narrative [Text Block]	rr_StrategyNarrativeTextBlock	The Fund pursues its investment objective by normally investing 50-60% of its assets in fixed-income securities and investing the remainder in equity securities and cash equivalents. Fixed-Income Securities.  The Fund’s fixed-income investments generate total return from a combination of current income and capital appreciation, but income is usually the dominant portion. The Fund normally invests the portion of its assets allocated to fixed-income investments in a multi-sector portfolio of U.S. and non-U.S. debt securities that the fixed-income portfolio managers believe have high income potential. The Fund may invest up to 65% of the fixed-income portion of its assets in below investment grade securities. The Fund’s fixed-income investment sectors include, but are not limited to: (i) government notes and bonds; (ii) corporate bonds, including high-yield/high-risk bonds, also known as “junk” bonds; (iii) commercial loans; (iv) commercial and residential mortgage-backed securities; (v) asset-backed securities; (vi) convertible securities and preferred stock; and (vii) emerging market debt. The Fund may invest in fixed-income securities of varying maturities. The Fund’s fixed-income portfolio managers believe that by investing in multiple sectors that potentially have low correlation to each other, the volatility of the Fund’s fixed-income portion may be reduced. The Fund may not have exposure to all of these investment sectors, and the Fund’s exposure to any one investment sector will vary over time. The Fund may also invest in money market instruments and zero-coupon bonds. The Fund may enter into “to be announced” or “TBA” commitments when purchasing mortgage-backed securities or other securities. The Fund may also invest in floating rate obligations, such as collateralized loan obligations, floating rate senior secured syndicated bank loans, floating rate unsecured loans, and other floating rate bonds, loans and notes. Floating rate obligations feature rates that reset regularly, maintaining a fixed spread over the London InterBank Offered Rate (“LIBOR”) or the prime rates of large money-center banks. The interest rates on floating rate obligations typically reset quarterly, although rates on some obligations may adjust at other intervals. In addition to considering economic factors such as the effect of interest rates on the Fund’s fixed-income investments, the Fund’s fixed-income portfolio managers apply a “bottom up” approach in choosing investments. This means that the portfolio managers look at income-producing securities one at a time to determine if a security is an attractive investment opportunity and if it is consistent with the Fund’s investment policies. The portfolio managers additionally consider the expected risk-adjusted return on a particular investment and the Fund’s overall risk allocations and volatility. Equity Securities.  The Fund’s equity investments generate total return from a combination of capital appreciation and current income. Such equity investments may include companies of any size, but the Fund will invest primarily in large- and mid-sized companies whose stock prices the portfolio managers believe to be undervalued or have the potential for high relative dividend yields, or both. The Fund’s equity portfolio managers invest in companies which have fallen out of favor with the market or that appear to be temporarily misunderstood by the investment community. The Fund’s equity portfolio managers generally look for companies with: strong balance sheets and solid recurring free cash flows; attractive relative and absolute valuation ratios or that have underperformed recently; and favorable reward to risk characteristics The portfolio managers’ philosophy is to weigh a security’s downside risk before considering its upside potential, which may help provide an element of capital preservation. The Fund may also invest in foreign securities, which may include investments in emerging markets. The Fund may also invest its assets in derivatives, which are instruments that 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 use index and single-name credit default swaps, forward currency exchange contracts, interest rate futures, and put and call options. The Fund may use derivatives for various investment purposes, such as to manage portfolio or currency risk, enhance returns, manage duration, or for hedging purposes. Janus Capital manages the Fund’s fixed-income investments and Perkins manages the Fund’s equity investments. The Fund’s portfolio managers collaborate in determining the Fund’s overall asset allocation. The Fund may periodically adjust its mix of equity and fixed-income investments in response to changing economic and market conditions, including outside the range of 50-60% of its assets in fixed-income securities. Due to the nature of the fixed-income securities in which the Fund invests, it may have relatively high portfolio turnover compared to other funds.
Risk [Heading]	rr_RiskHeading	<b>PRINCIPAL INVESTMENT RISKS</b>
Risk Narrative [Text Block]	rr_RiskNarrativeTextBlock	The biggest risk is that the Fund’s returns and yields will vary, and you could lose money. The Fund is designed for long-term investors seeking a portfolio including common stocks and bonds selected for their potential to produce capital appreciation and current income. Common stocks tend to be more volatile than many other investment choices. Fixed-Income Securities Risk.  The Fund invests in a variety of fixed-income securities. Typically, the values of fixed-income securities change inversely with prevailing interest rates. Therefore, a fundamental risk of fixed-income securities is interest rate risk, which is the risk that the value of such securities will generally decline as prevailing interest rates rise, which may cause the Fund’s net asset value to likewise decrease. For example, while securities with longer maturities and durations tend to produce higher yields, they also tend to be more sensitive to changes in prevailing interest rates and are therefore more volatile than shorter-term securities and are subject to greater market fluctuations as a result of changes in interest rates. Further, during periods of very low or negative interest rates, the Fund may not be able to maintain positive returns. The Fund may be subject to heightened interest rate risk because the Federal Reserve has ended its monetary stimulus program known as quantitative easing and interest rates are near historically low levels. The Federal Reserve raised the federal funds rate several times in recent periods and has signaled additional increases in the near future. To the extent the Federal Reserve continues to raise rates, there is a risk that the fixed-income markets will experience increased volatility and that the liquidity of certain Fund investments may be reduced. These developments could cause the Fund’s net asset value to fluctuate or make it more difficult for the Fund to accurately value its securities. These developments or others also could cause the Fund to face increased shareholder redemptions, which may lead to increased portfolio turnover and transaction costs, or could force the Fund to liquidate investments at disadvantageous times or prices, therefore adversely affecting the Fund as well as the value of your investment. The amount of assets deemed illiquid remaining within the Fund may also increase, making it more difficult to meet shareholder redemptions and further adversely affecting the value of the Fund. How specific fixed-income securities may react to changes in interest rates will depend on the specific characteristics of each security. Fixed-income securities are also subject to credit risk, prepayment risk, valuation risk, extension risk, and liquidity risk. Credit risk is the risk that the credit strength of an issuer of a fixed-income security will weaken and/or that the issuer will be unable to make timely principal and interest payments and that the security may go into default. Prepayment risk is the risk that during periods of falling interest rates, certain fixed-income securities with higher interest rates, such as mortgage- and asset-backed securities, may be prepaid by their issuers thereby reducing the amount of interest payments. Valuation risk is the risk that one or more of the fixed-income securities in which the Fund invests are priced differently than the value realized upon such security’s sale. In times of market instability, valuation may be more difficult. Extension risk is the risk that borrowers may pay off their debt obligations more slowly in times of rising interest rates, which will lengthen the duration of the portfolio. Liquidity risk is the risk that fixed-income securities may be difficult or impossible to sell at the time that the portfolio managers would like or at the price the portfolio managers believe the security is currently worth. High-Yield/High-Risk Debt Securities Risk.  High-yield/high-risk debt securities are considered speculative and may be more sensitive than other types of debt securities to economic changes, political changes, or adverse developments specific to the company that issued the debt security, which may adversely affect their value. High-yield/high-risk debt securities are debt securities rated below investment grade by the primary rating agencies such as Standard & Poor’s Ratings Services, Fitch, Inc., and Moody’s Investors Service, Inc. or are unrated debt securities of similar quality. The value of lower quality debt securities generally is more dependent on credit risk than investment grade debt securities. Issuers of high-yield/high-risk debt securities may not be as strong financially as those issuing debt securities with higher credit ratings and are more vulnerable to real or perceived economic changes, political changes, or adverse developments specific to the issuer. In addition, the junk bond market can experience sudden and sharp price swings. 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. 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 the equity portfolio managers. Mid-Sized Companies Risk.  The Fund’s investments in securities issued by mid-sized companies may involve greater risks than are customarily associated with larger, more established companies. 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. Mortgage- and Asset-Backed Securities Risk.  Mortgage- and asset-backed securities represent interests in “pools” of commercial or residential mortgages or other assets, including consumer loans or receivables. Mortgage- and asset-backed securities tend to be more sensitive to changes in interest rates than other types of debt securities. Investments in mortgage- and asset-backed securities are subject to both extension risk, where borrowers pay off their debt obligations more slowly in times of rising interest rates, and prepayment risk, where borrowers pay off their debt obligations sooner than expected in times of declining interest rates. These risks may reduce the Fund’s returns. In addition, investments in mortgage- and asset-backed securities, including those comprised of subprime mortgages, may be subject to a higher degree of credit risk, valuation risk, and liquidity risk than various other types of fixed-income securities. TBA Commitments Risk.  The Fund may enter into “to be announced” or “TBA” commitments for mortgage-backed securities. There can be no assurance that a security purchased on a forward commitment basis will ultimately be issued or delivered by the counterparty. During the settlement period, the Fund will still bear the risk of any decline in the value of the security to be delivered. Because TBA commitments do not require the purchase and sale of identical securities, the characteristics of the security delivered to the Fund may be less favorable than the security delivered to the dealer. If the counterparty to a transaction fails to deliver the securities, the Fund could suffer a loss. At the time of its acquisition, a TBA security may be valued at less than the purchase price. Loan Risk.  The Fund may invest in a variety of loans. Bank loans are obligations of companies or other entities entered into in connection with recapitalizations, acquisitions, and refinancings. The Fund’s investments in bank loans are generally acquired as a participation interest in, or assignment of, loans originated by a lender or other financial institution. These investments may include institutionally-traded floating and fixed-rate debt securities. The bank loans underlying these securities often involve borrowers with low credit ratings whose financial conditions are troubled or uncertain, including companies that are highly leveraged or in bankruptcy proceedings. Participation interests and assignments involve credit, interest rate, and liquidity risk. Sovereign Debt Risk.  The Fund may invest in U.S. and non-U.S. government debt securities (“sovereign debt”). Some investments in sovereign debt, such as U.S. sovereign debt, are considered low risk. However, investments in sovereign debt, especially the debt of less developed countries, can involve a high degree of risk, including the risk that the governmental entity that controls the repayment of sovereign debt may not be willing or able to repay the principal and/or to pay the interest on its sovereign debt in a timely manner. A sovereign debtor’s willingness or ability to satisfy its debt obligation may be affected by various factors including, but not limited to, its cash flow situation, the extent of its foreign currency reserves, the availability of foreign exchange when a payment is due, and the relative size of its debt position in relation to its economy as a whole. In the event of default, there may be limited or no legal remedies for collecting sovereign debt and there may be no bankruptcy proceedings through which the Fund may collect all or part of the sovereign debt that a governmental entity has not repaid. In addition, to the extent the Fund invests in non-U.S. sovereign debt, it may be subject to currency risk. Floating Rate Obligations Risk.  There may be a number of intermediate participants in floating rate obligation transactions and loan agreements that have specific rights and obligations, and terms and conditions. Unexpected changes in the interest rates on floating rate obligations could result in losses to the Fund. In addition, the secondary market on which floating rate obligations are traded may be less liquid than the market for investment grade securities or other types of income-producing securities, which may have an adverse impact on their market price. There is also a potential that there is no active market to trade floating rate obligations and that there may be restrictions on their transfer. As a result, the Fund may be unable to sell assignments or participations at the desired time or may be able to sell only at a price less than fair market value. Foreign Exposure Risk.  The Fund may have 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 to a large degree 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. To the extent the Fund invests in foreign debt securities, such investments are sensitive to changes in interest rates. Additionally, investments in securities of foreign governments involve the risk that a foreign government may not be willing or able to pay interest or repay principal when due. The Fund’s investments in emerging market countries 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 markets securities 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, making these investments 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 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 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. Some of the risks of investing directly in foreign and emerging market securities may be reduced when the Fund invests indirectly in foreign securities through various other investment vehicles including derivatives, which also involve other risks. Currency Risk.  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. 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. 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 (the “Internal Revenue Code”) 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. Derivatives Risk.  Derivatives can be highly 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 the Fund. 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 can be less liquid than other types of investments and 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. To the extent the Fund enters into short derivative positions, the Fund may be exposed to risks similar to those associated with short sales, including the risk that the Fund’s losses are theoretically unlimited. In addition, to the extent that the Fund uses forward currency exchange contracts, there is a risk that unanticipated changes in currency prices may negatively impact the Fund’s performance, among other things. The Fund may use derivatives for hedging purposes. Hedging with derivatives may increase expenses, and there is no guarantee that a hedging strategy will work. While hedging can reduce or eliminate losses, it can also reduce or eliminate gains or cause losses if the market moves in a manner different from that anticipated by the portfolio managers or if the cost of the derivative outweighs the benefit of the hedge. Allocation Risk.  The Fund’s ability to achieve its investment objective depends largely upon the allocation of assets among the equity and fixed asset categories. You could lose money on your investment in the Fund as a result of these allocations. Portfolio management may favor an asset category that underperforms relative to other asset categories. For example, the Fund may be overweighted in fixed-income securities when the stock market is rising and the fixed-income market is falling. Additionally, periodic rebalancing of Fund assets among asset categories may result in increased transaction costs, which may have a negative effect on the Fund’s performance. 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. 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. 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	The biggest risk is that the Fund’s returns and yields will vary, and you could lose money.
Risk Not Insured Depository Institution [Text]	rr_RiskNotInsuredDepositoryInstitution	<i>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.</i>
Bar Chart and Performance Table [Heading]	rr_BarChartAndPerformanceTableHeading	<b>PERFORMANCE INFORMATION</b>
Performance Narrative [Text Block]	rr_PerformanceNarrativeTextBlock	The following information provides some indication of the risks of investing in the Fund by showing how the Fund’s performance has varied over time. Class A Shares, Class C Shares, Class S Shares, Class I Shares, and Class T Shares of the Fund commenced operations with the Fund’s inception. Class N Shares of the Fund commenced operations on August 4, 2017. The performance shown for Class A Shares, Class C Shares, Class S Shares, Class I Shares, and Class T Shares is calculated using the fees and expenses of each respective share class, net of any applicable fee and expense limitations or waivers. The performance shown for Class N Shares for periods prior to August 4, 2017, reflects the performance of the Fund’s Class I Shares, calculated using the fees and expenses of Class N Shares, without the effect of any fee and expense limitations or waivers. If Class N Shares of the Fund had been available during periods prior to August 4, 2017, the performance may have been different. 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 broad-based securities market indices. 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/performance or by calling 1-877-335-2687.
Performance Information Illustrates Variability of Returns [Text]	rr_PerformanceInformationIllustratesVariabilityOfReturns	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.<br/><br/>The bar chart depicts the change in performance from year to year during the periods indicated.
Performance Additional Market Index [Text]	rr_PerformanceAdditionalMarketIndex	The table compares the Fund’s average annual returns for the periods indicated to broad-based securities market indices. All figures assume reinvestment of dividends and distributions.
Performance Availability Phone [Text]	rr_PerformanceAvailabilityPhone	<i>1-877-335-2687</i>
Performance Availability Website Address [Text]	rr_PerformanceAvailabilityWebSiteAddress	<i>janushenderson.com/performance</i>
Performance Past Does Not Indicate Future [Text]	rr_PerformancePastDoesNotIndicateFuture	<i>The Fund’s past performance (before and after taxes) does not necessarily indicate how it will perform in the future.</i>
Bar Chart [Heading]	rr_BarChartHeading	<b>Annual Total Returns for Class I Shares</b> (calendar year-end)
Bar Chart Does Not Reflect Sales Loads [Text]	rr_BarChartDoesNotReflectSalesLoads	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.
Bar Chart Closing [Text Block]	rr_BarChartClosingTextBlock	Best Quarter:  4th Quarter 2011  7.22%          Worst Quarter:  3rd Quarter 2011  – 7.73%
Year to Date Return, Label	rr_YearToDateReturnLabel	The Fund’s year-to-date return as of the calendar quarter ended September 30, 2018 was 2.79%.
Performance Table Heading	rr_PerformanceTableHeading	<b>Average Annual Total Returns</b> (periods ended 12/31/17)
Performance Table Market Index Changed	rr_PerformanceTableMarketIndexChanged	Prior to August 31, 2018, the underlying composition of the Value Income Index reflected a blend of the total returns from the Russell 1000<sup>®</sup> Value Index (50%) and the Bloomberg Barclays U.S. Aggregate Bond Index (50%). Effective August 31, 2018, the Fund changed its investment strategy to increase its allocation to fixed-income instruments and to provide greater flexibility to invest across multiple sectors. To better reflect this strategy change, effective August 31, 2018, the underlying composition of the Value Income Index changed to reflect a blend of the total returns from the Russell 1000<sup>®</sup> Value Index (40%) and the Bloomberg Barclays U.S. Aggregate Bond Index (60%). The indices are described below.<ul type="square"><li>The Russell 1000<sup>®</sup> Value Index measures the performance of those Russell 1000<sup>®</sup> companies with lower price-to-book ratios and lower forecasted growth values.</li></ul><ul type="square"><li>The Bloomberg Barclays U.S. Aggregate Bond Index is made up of the Bloomberg Barclays U.S. Government/Corporate Bond Index, Mortgage-Backed Securities Index, and Asset-Backed Securities Index, including securities that are of investment grade quality or better, have at least one year to maturity, and have an outstanding par value of at least $100 million.</li></ul><ul type="square"><li>The Value Income Index (Russell 1000<sup>®</sup> Value Index (40%) and the Bloomberg Barclays U.S. Aggregate Bond Index (60%)) is an internally-calculated, hypothetical combination of unmanaged indices that combines total returns from the Russell 1000<sup>®</sup> Value Index (40%) and the Bloomberg Barclays U.S. Aggregate Bond Index (60%).</li></ul><ul type="square"><li>The Value Income Index (Russell 1000<sup>®</sup> Value Index (50%) and the Bloomberg Barclays U.S. Aggregate Bond Index (50%)) is an internally-calculated, hypothetical combination of unmanaged indices that combines total returns from the Russell 1000<sup>®</sup> Value Index (50%) and the Bloomberg Barclays U.S. Aggregate Bond Index (50%).</li></ul>
Performance Table Uses Highest Federal Rate	rr_PerformanceTableUsesHighestFederalRate	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.
Performance Table Not Relevant to Tax Deferred	rr_PerformanceTableNotRelevantToTaxDeferred	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-deferred account, such as a 401(k) plan or an IRA.
Performance Table One Class of after Tax Shown [Text]	rr_PerformanceTableOneClassOfAfterTaxShown	After-tax returns are only shown for Class I Shares of the Fund. After-tax returns for the other classes of Shares will vary from those shown for Class I Shares due to varying sales charges (as applicable), fees, and expenses among the classes.
Performance Table Narrative	rr_PerformanceTableNarrativeTextBlock	The Fund’s primary benchmark index is the Russell 1000® Value Index. The Fund also compares its performance to the Bloomberg Barclays U.S. Aggregate Bond Index and the Value Income Index. Prior to August 31, 2018, the underlying composition of the Value Income Index reflected a blend of the total returns from the Russell 1000® Value Index (50%) and the Bloomberg Barclays U.S. Aggregate Bond Index (50%). Effective August 31, 2018, the Fund changed its investment strategy to increase its allocation to fixed-income instruments and to provide greater flexibility to invest across multiple sectors. To better reflect this strategy change, effective August 31, 2018, the underlying composition of the Value Income Index changed to reflect a blend of the total returns from the Russell 1000® Value Index (40%) and the Bloomberg Barclays U.S. Aggregate Bond Index (60%). The indices are described below. The Russell 1000® Value Index measures the performance of those Russell 1000® companies with lower price-to-book ratios and lower forecasted growth values. The Bloomberg Barclays U.S. Aggregate Bond Index is made up of the Bloomberg Barclays U.S. Government/Corporate Bond Index, Mortgage-Backed Securities Index, and Asset-Backed Securities Index, including securities that are of investment grade quality or better, have at least one year to maturity, and have an outstanding par value of at least $100 million. The Value Income Index (Russell 1000® Value Index (40%) and the Bloomberg Barclays U.S. Aggregate Bond Index (60%)) is an internally-calculated, hypothetical combination of unmanaged indices that combines total returns from the Russell 1000® Value Index (40%) and the Bloomberg Barclays U.S. Aggregate Bond Index (60%). The Value Income Index (Russell 1000® Value Index (50%) and the Bloomberg Barclays U.S. Aggregate Bond Index (50%)) is an internally-calculated, hypothetical combination of unmanaged indices that combines total returns from the Russell 1000® Value Index (50%) and the Bloomberg Barclays U.S. Aggregate Bond Index (50%). 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-deferred account, such as a 401(k) plan or an IRA. After-tax returns are only shown for Class I Shares of the Fund. After-tax returns for the other classes of Shares will vary from those shown for Class I Shares due to varying sales charges (as applicable), fees, and expenses among the classes.
Performance Table Closing [Text Block]	rr_PerformanceTableClosingTextBlock	Updated performance information is available at janushenderson.com/performance or by calling 1-877-335-2687.
Janus Henderson Value Plus Income Fund | Class A, C, S, I, N, T Shares | Class A
Risk/Return:	rr_RiskReturnAbstract
Shareholder Fees Column [Text]	rr_ShareholderFeesColumnName	Class A
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
Operating Expenses Column [Text]	rr_OperatingExpensesColumnName	Class A
Management Fees	rr_ManagementFeesOverAssets	0.60%
Distribution/Service (12b-1) Fees	rr_DistributionAndService12b1FeesOverAssets	0.25%
Other Expenses	rr_OtherExpensesOverAssets	0.52%
Total Annual Fund Operating Expenses	rr_ExpensesOverAssets	1.37%	[1]
Fee Waiver	rr_FeeWaiverOrReimbursementOverAssets	0.42%	[1]
Total Annual Fund Operating Expenses After Fee Waiver	rr_NetExpensesOverAssets	0.95%	[1]
Expense Example, By Year, Column [Text]	rr_ExpenseExampleByYearColumnName	Class A Shares
1 Year	rr_ExpenseExampleYear01	$ 706
3 Years	rr_ExpenseExampleYear03	984
5 Years	rr_ExpenseExampleYear05	1,282
10 Years	rr_ExpenseExampleYear10	$ 2,127
Expense Example, No Redemption, By Year, Column [Text]	rr_ExpenseExampleNoRedemptionByYearColumnName	Class A Shares
1 Year	rr_ExpenseExampleNoRedemptionYear01	$ 706
3 Years	rr_ExpenseExampleNoRedemptionYear03	984
5 Years	rr_ExpenseExampleNoRedemptionYear05	1,282
10 Years	rr_ExpenseExampleNoRedemptionYear10	$ 2,127
Janus Henderson Value Plus Income Fund | Class A, C, S, I, N, T Shares | Class C
Risk/Return:	rr_RiskReturnAbstract
Shareholder Fees Column [Text]	rr_ShareholderFeesColumnName	Class C
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%
Operating Expenses Column [Text]	rr_OperatingExpensesColumnName	Class C
Management Fees	rr_ManagementFeesOverAssets	0.60%
Distribution/Service (12b-1) Fees	rr_DistributionAndService12b1FeesOverAssets	1.00%
Other Expenses	rr_OtherExpensesOverAssets	0.52%
Total Annual Fund Operating Expenses	rr_ExpensesOverAssets	2.12%	[1]
Fee Waiver	rr_FeeWaiverOrReimbursementOverAssets	0.42%	[1]
Total Annual Fund Operating Expenses After Fee Waiver	rr_NetExpensesOverAssets	1.70%	[1]
Expense Example, By Year, Column [Text]	rr_ExpenseExampleByYearColumnName	Class C Shares
1 Year	rr_ExpenseExampleYear01	$ 315
3 Years	rr_ExpenseExampleYear03	664
5 Years	rr_ExpenseExampleYear05	1,139
10 Years	rr_ExpenseExampleYear10	$ 2,452
Expense Example, No Redemption, By Year, Column [Text]	rr_ExpenseExampleNoRedemptionByYearColumnName	Class C Shares
1 Year	rr_ExpenseExampleNoRedemptionYear01	$ 215
3 Years	rr_ExpenseExampleNoRedemptionYear03	664
5 Years	rr_ExpenseExampleNoRedemptionYear05	1,139
10 Years	rr_ExpenseExampleNoRedemptionYear10	$ 2,452
Janus Henderson Value Plus Income Fund | Class A, C, S, I, N, T Shares | Class S
Risk/Return:	rr_RiskReturnAbstract
Shareholder Fees Column [Text]	rr_ShareholderFeesColumnName	Class S
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
Operating Expenses Column [Text]	rr_OperatingExpensesColumnName	Class S
Management Fees	rr_ManagementFeesOverAssets	0.60%
Distribution/Service (12b-1) Fees	rr_DistributionAndService12b1FeesOverAssets	0.25%
Other Expenses	rr_OtherExpensesOverAssets	0.78%
Total Annual Fund Operating Expenses	rr_ExpensesOverAssets	1.63%	[1]
Fee Waiver	rr_FeeWaiverOrReimbursementOverAssets	0.45%	[1]
Total Annual Fund Operating Expenses After Fee Waiver	rr_NetExpensesOverAssets	1.18%	[1]
Expense Example, By Year, Column [Text]	rr_ExpenseExampleByYearColumnName	Class S Shares
1 Year	rr_ExpenseExampleYear01	$ 166
3 Years	rr_ExpenseExampleYear03	514
5 Years	rr_ExpenseExampleYear05	887
10 Years	rr_ExpenseExampleYear10	$ 1,933
Expense Example, No Redemption, By Year, Column [Text]	rr_ExpenseExampleNoRedemptionByYearColumnName	Class S Shares
1 Year	rr_ExpenseExampleNoRedemptionYear01	$ 166
3 Years	rr_ExpenseExampleNoRedemptionYear03	514
5 Years	rr_ExpenseExampleNoRedemptionYear05	887
10 Years	rr_ExpenseExampleNoRedemptionYear10	$ 1,933
Janus Henderson Value Plus Income Fund | Class A, C, S, I, N, T Shares | Class I
Risk/Return:	rr_RiskReturnAbstract
Shareholder Fees Column [Text]	rr_ShareholderFeesColumnName	Class I
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
Operating Expenses Column [Text]	rr_OperatingExpensesColumnName	Class I
Management Fees	rr_ManagementFeesOverAssets	0.60%
Distribution/Service (12b-1) Fees	rr_DistributionAndService12b1FeesOverAssets	none
Other Expenses	rr_OtherExpensesOverAssets	0.56%
Total Annual Fund Operating Expenses	rr_ExpensesOverAssets	1.16%	[1]
Fee Waiver	rr_FeeWaiverOrReimbursementOverAssets	0.40%	[1]
Total Annual Fund Operating Expenses After Fee Waiver	rr_NetExpensesOverAssets	0.76%	[1]
Expense Example, By Year, Column [Text]	rr_ExpenseExampleByYearColumnName	Class I Shares
1 Year	rr_ExpenseExampleYear01	$ 118
3 Years	rr_ExpenseExampleYear03	368
5 Years	rr_ExpenseExampleYear05	638
10 Years	rr_ExpenseExampleYear10	$ 1,409
Expense Example, No Redemption, By Year, Column [Text]	rr_ExpenseExampleNoRedemptionByYearColumnName	Class I Shares
1 Year	rr_ExpenseExampleNoRedemptionYear01	$ 118
3 Years	rr_ExpenseExampleNoRedemptionYear03	368
5 Years	rr_ExpenseExampleNoRedemptionYear05	638
10 Years	rr_ExpenseExampleNoRedemptionYear10	$ 1,409
2011	rr_AnnualReturn2011	3.74%
2012	rr_AnnualReturn2012	11.75%
2013	rr_AnnualReturn2013	13.81%
2014	rr_AnnualReturn2014	9.34%
2015	rr_AnnualReturn2015	(2.45%)
2016	rr_AnnualReturn2016	11.03%
2017	rr_AnnualReturn2017	9.57%
Bar Chart, Year to Date Return, Date	rr_BarChartYearToDateReturnDate	Sep. 30, 2018
Bar Chart, Year to Date Return	rr_BarChartYearToDateReturn	2.79%
Highest Quarterly Return, Label	rr_HighestQuarterlyReturnLabel	<b>Best Quarter:</b>
Highest Quarterly Return, Date	rr_BarChartHighestQuarterlyReturnDate	Dec. 31, 2011
Highest Quarterly Return	rr_BarChartHighestQuarterlyReturn	7.22%
Lowest Quarterly Return, Label	rr_LowestQuarterlyReturnLabel	<b>Worst Quarter:</b>
Lowest Quarterly Return, Date	rr_BarChartLowestQuarterlyReturnDate	Sep. 30, 2011
Lowest Quarterly Return	rr_BarChartLowestQuarterlyReturn	(7.73%)
Janus Henderson Value Plus Income Fund | Class A, C, S, I, N, T Shares | Class N
Risk/Return:	rr_RiskReturnAbstract
Shareholder Fees Column [Text]	rr_ShareholderFeesColumnName	Class N
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
Operating Expenses Column [Text]	rr_OperatingExpensesColumnName	Class N
Management Fees	rr_ManagementFeesOverAssets	0.60%
Distribution/Service (12b-1) Fees	rr_DistributionAndService12b1FeesOverAssets	none
Other Expenses	rr_OtherExpensesOverAssets	0.65%
Total Annual Fund Operating Expenses	rr_ExpensesOverAssets	1.25%	[1]
Fee Waiver	rr_FeeWaiverOrReimbursementOverAssets	0.57%	[1]
Total Annual Fund Operating Expenses After Fee Waiver	rr_NetExpensesOverAssets	0.68%	[1]
Expense Example, By Year, Column [Text]	rr_ExpenseExampleByYearColumnName	Class N Shares
1 Year	rr_ExpenseExampleYear01	$ 127
3 Years	rr_ExpenseExampleYear03	397
5 Years	rr_ExpenseExampleYear05	686
10 Years	rr_ExpenseExampleYear10	$ 1,511
Expense Example, No Redemption, By Year, Column [Text]	rr_ExpenseExampleNoRedemptionByYearColumnName	Class N Shares
1 Year	rr_ExpenseExampleNoRedemptionYear01	$ 127
3 Years	rr_ExpenseExampleNoRedemptionYear03	397
5 Years	rr_ExpenseExampleNoRedemptionYear05	686
10 Years	rr_ExpenseExampleNoRedemptionYear10	$ 1,511
Janus Henderson Value Plus Income Fund | Class A, C, S, I, N, T Shares | Class T
Risk/Return:	rr_RiskReturnAbstract
Shareholder Fees Column [Text]	rr_ShareholderFeesColumnName	Class T
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
Operating Expenses Column [Text]	rr_OperatingExpensesColumnName	Class T
Management Fees	rr_ManagementFeesOverAssets	0.60%
Distribution/Service (12b-1) Fees	rr_DistributionAndService12b1FeesOverAssets	none
Other Expenses	rr_OtherExpensesOverAssets	0.75%
Total Annual Fund Operating Expenses	rr_ExpensesOverAssets	1.35%	[1]
Fee Waiver	rr_FeeWaiverOrReimbursementOverAssets	0.42%	[1]
Total Annual Fund Operating Expenses After Fee Waiver	rr_NetExpensesOverAssets	0.93%	[1]
Expense Example, By Year, Column [Text]	rr_ExpenseExampleByYearColumnName	Class T Shares
1 Year	rr_ExpenseExampleYear01	$ 137
3 Years	rr_ExpenseExampleYear03	428
5 Years	rr_ExpenseExampleYear05	739
10 Years	rr_ExpenseExampleYear10	$ 1,624
Expense Example, No Redemption, By Year, Column [Text]	rr_ExpenseExampleNoRedemptionByYearColumnName	Class T Shares
1 Year	rr_ExpenseExampleNoRedemptionYear01	$ 137
3 Years	rr_ExpenseExampleNoRedemptionYear03	428
5 Years	rr_ExpenseExampleNoRedemptionYear05	739
10 Years	rr_ExpenseExampleNoRedemptionYear10	$ 1,624
Janus Henderson Value Plus Income Fund | Class A, C, S, I, N, T Shares | Return Before Taxes | Class A
Risk/Return:	rr_RiskReturnAbstract
Average Annual Return, Column Name	rr_AverageAnnualReturnColumnName	Class A Shares
Label	rr_AverageAnnualReturnLabel	Return Before Taxes	[2]
1 Year	rr_AverageAnnualReturnYear01	3.02%
5 Years	rr_AverageAnnualReturnYear05	6.59%
Since Inception	rr_AverageAnnualReturnSinceInception	7.71%
Inception Date	rr_AverageAnnualReturnInceptionDate	Jul. 30, 2010
Janus Henderson Value Plus Income Fund | Class A, C, S, I, N, T Shares | Return Before Taxes | Class C
Risk/Return:	rr_RiskReturnAbstract
Average Annual Return, Column Name	rr_AverageAnnualReturnColumnName	Class C Shares
Label	rr_AverageAnnualReturnLabel	Return Before Taxes	[3]
1 Year	rr_AverageAnnualReturnYear01	7.53%
5 Years	rr_AverageAnnualReturnYear05	7.08%
Since Inception	rr_AverageAnnualReturnSinceInception	7.83%
Inception Date	rr_AverageAnnualReturnInceptionDate	Jul. 30, 2010
Janus Henderson Value Plus Income Fund | Class A, C, S, I, N, T Shares | Return Before Taxes | Class S
Risk/Return:	rr_RiskReturnAbstract
Average Annual Return, Column Name	rr_AverageAnnualReturnColumnName	Class S Shares
Label	rr_AverageAnnualReturnLabel	Return Before Taxes
1 Year	rr_AverageAnnualReturnYear01	9.15%
5 Years	rr_AverageAnnualReturnYear05	7.81%
Since Inception	rr_AverageAnnualReturnSinceInception	8.46%
Inception Date	rr_AverageAnnualReturnInceptionDate	Jul. 30, 2010
Janus Henderson Value Plus Income Fund | Class A, C, S, I, N, T Shares | Return Before Taxes | Class I
Risk/Return:	rr_RiskReturnAbstract
Average Annual Return, Column Name	rr_AverageAnnualReturnColumnName	Class I Shares
Label	rr_AverageAnnualReturnLabel	Return Before Taxes
1 Year	rr_AverageAnnualReturnYear01	9.57%
5 Years	rr_AverageAnnualReturnYear05	8.11%
Since Inception	rr_AverageAnnualReturnSinceInception	8.82%
Inception Date	rr_AverageAnnualReturnInceptionDate	Jul. 30, 2010
Janus Henderson Value Plus Income Fund | Class A, C, S, I, N, T Shares | Return Before Taxes | Class N
Risk/Return:	rr_RiskReturnAbstract
Average Annual Return, Column Name	rr_AverageAnnualReturnColumnName	Class N Shares
Label	rr_AverageAnnualReturnLabel	Return Before Taxes
1 Year	rr_AverageAnnualReturnYear01	9.28%
5 Years	rr_AverageAnnualReturnYear05	7.72%
Since Inception	rr_AverageAnnualReturnSinceInception	8.40%
Inception Date	rr_AverageAnnualReturnInceptionDate	Jul. 30, 2010
Janus Henderson Value Plus Income Fund | Class A, C, S, I, N, T Shares | Return Before Taxes | Class T
Risk/Return:	rr_RiskReturnAbstract
Average Annual Return, Column Name	rr_AverageAnnualReturnColumnName	Class T Shares
Label	rr_AverageAnnualReturnLabel	Return Before Taxes
1 Year	rr_AverageAnnualReturnYear01	9.30%
5 Years	rr_AverageAnnualReturnYear05	7.96%
Since Inception	rr_AverageAnnualReturnSinceInception	8.65%
Inception Date	rr_AverageAnnualReturnInceptionDate	Jul. 30, 2010
Janus Henderson Value Plus Income Fund | Class A, C, S, I, N, T Shares | Return After Taxes on Distributions | Class I
Risk/Return:	rr_RiskReturnAbstract
Average Annual Return, Column Name	rr_AverageAnnualReturnColumnName	Class I Shares
Label	rr_AverageAnnualReturnLabel	Return After Taxes on Distributions
1 Year	rr_AverageAnnualReturnYear01	7.65%
5 Years	rr_AverageAnnualReturnYear05	6.05%
Since Inception	rr_AverageAnnualReturnSinceInception	6.88%
Inception Date	rr_AverageAnnualReturnInceptionDate	Jul. 30, 2010
Janus Henderson Value Plus Income Fund | Class A, C, S, I, N, T Shares | Return After Taxes on Distributions and Sale of Fund Shares | Class I
Risk/Return:	rr_RiskReturnAbstract
Average Annual Return, Column Name	rr_AverageAnnualReturnColumnName	Class I Shares
Label	rr_AverageAnnualReturnLabel	Return After Taxes on Distributions and Sale of Fund Shares
1 Year	rr_AverageAnnualReturnYear01	6.43%
5 Years	rr_AverageAnnualReturnYear05	5.83%
Since Inception	rr_AverageAnnualReturnSinceInception	6.49%
Inception Date	rr_AverageAnnualReturnInceptionDate	Jul. 30, 2010
Janus Henderson Value Plus Income Fund | Class A, C, S, I, N, T Shares | Russell 1000® Value Index (reflects no deduction for expenses, fees, or taxes)
Risk/Return:	rr_RiskReturnAbstract
Label	rr_AverageAnnualReturnLabel	Russell 1000<sup>®</sup> Value Index
1 Year	rr_AverageAnnualReturnYear01	13.66%
5 Years	rr_AverageAnnualReturnYear05	14.04%
Since Inception	rr_AverageAnnualReturnSinceInception	13.70%
Inception Date	rr_AverageAnnualReturnInceptionDate	Jul. 30, 2010
Janus Henderson Value Plus Income Fund | Class A, C, S, I, N, T Shares | Bloomberg Barclays U.S. Aggregate Bond Index (reflects no deduction for expenses, fees, or taxes)
Risk/Return:	rr_RiskReturnAbstract
Label	rr_AverageAnnualReturnLabel	Bloomberg Barclays U.S. Aggregate Bond Index
1 Year	rr_AverageAnnualReturnYear01	3.54%
5 Years	rr_AverageAnnualReturnYear05	2.10%
Since Inception	rr_AverageAnnualReturnSinceInception	3.03%
Inception Date	rr_AverageAnnualReturnInceptionDate	Jul. 30, 2010
Janus Henderson Value Plus Income Fund | Class A, C, S, I, N, T Shares | Value Income Index (Russell 1000® Value Index (40%) and the Bloomberg Barclays U.S. Aggregate Bond Index (60%)) (reflects no deduction for expenses, fees, or taxes)
Risk/Return:	rr_RiskReturnAbstract
Label	rr_AverageAnnualReturnLabel	Value Income Index (Russell 1000<sup>®</sup> Value Index (40%) and the Bloomberg Barclays U.S. Aggregate Bond Index (60%))
1 Year	rr_AverageAnnualReturnYear01	7.53%
5 Years	rr_AverageAnnualReturnYear05	6.87%
Since Inception	rr_AverageAnnualReturnSinceInception	7.38%
Inception Date	rr_AverageAnnualReturnInceptionDate	Jul. 30, 2010
Janus Henderson Value Plus Income Fund | Class A, C, S, I, N, T Shares | Value Income Index (Russell 1000® Value Index (50%) and the Bloomberg Barclays U.S. Aggregate Bond Index (50%)) (reflects no deduction for expenses, fees, or taxes)
Risk/Return:	rr_RiskReturnAbstract
Label	rr_AverageAnnualReturnLabel	Value Income Index (Russell 1000<sup>®</sup> Value Index (50%) and the Bloomberg Barclays U.S. Aggregate Bond Index (50%))
1 Year	rr_AverageAnnualReturnYear01	8.54%
5 Years	rr_AverageAnnualReturnYear05	8.07%
Since Inception	rr_AverageAnnualReturnSinceInception	8.46%
Inception Date	rr_AverageAnnualReturnInceptionDate	Jul. 30, 2010

[1] Janus Capital has contractually agreed to waive its investment advisory fee and/or reimburse operating expenses to the extent that the Fund’s total annual fund operating expenses (excluding the fees payable pursuant to a Rule 12b-1 plan, shareholder servicing fees, such as transfer agency fees (including out-of-pocket costs), administrative services fees and any networking/omnibus/administrative fees payable by any share class; brokerage commissions; interest; dividends; taxes; acquired fund fees and expenses; and extraordinary expenses) exceed 0.68% until at least November 1, 2019. The contractual waiver may be terminated or modified prior to this date only at the discretion of the Board of Trustees.

[2] Calculated assuming maximum permitted sales loads.

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