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Risk/Return: rr_RiskReturnAbstract  
Registrant Name dei_EntityRegistrantName JANUS INVESTMENT FUND
Prospectus Date rr_ProspectusDate Oct. 28, 2015
Janus Real Return Fund | Class D Shares  
Risk/Return: rr_RiskReturnAbstract  
Risk/Return [Heading] rr_RiskReturnHeading FUND SUMMARY

Janus Real Return Fund
Objective [Heading] rr_ObjectiveHeading INVESTMENT OBJECTIVE
Objective, Primary [Text Block] rr_ObjectivePrimaryTextBlock Janus Real Return Fund seeks real return consistent with preservation of capital.
Expense [Heading] rr_ExpenseHeading FEES AND EXPENSES OF THE FUND
Expense Narrative [Text Block] rr_ExpenseNarrativeTextBlock This table describes the fees and expenses that you may pay if you buy and hold Shares of the Fund.
Operating Expenses Caption [Text] rr_OperatingExpensesCaption ANNUAL FUND OPERATING EXPENSES
(expenses that you pay each year as a percentage of the value of your investment)
Fee Waiver or Reimbursement over Assets, Date of Termination rr_FeeWaiverOrReimbursementOverAssetsDateOfTermination November 1, 2016
Portfolio Turnover [Heading] rr_PortfolioTurnoverHeading Portfolio Turnover: 
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 86% of the average value of its portfolio.
Portfolio Turnover, Rate rr_PortfolioTurnoverRate 86.00%
Expense Example [Heading] rr_ExpenseExampleHeading EXAMPLE:
Expense Example by Year [Heading] rr_ExpenseExampleByYearHeading The Example assumes that you invest $10,000 in the Fund for the time periods indicated, reinvest all dividends and distributions, and then redeem all of your Shares at the end of each period. The Example also assumes that your investment has a 5% return each year and that the Fund’s operating expenses without waivers remain the same. Although your actual costs may be higher or lower, based on these assumptions your costs would be:
Expense Example Narrative [Text Block] rr_ExpenseExampleNarrativeTextBlock The following Example is based on expenses without waivers. The Example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds.
Strategy [Heading] rr_StrategyHeading PRINCIPAL INVESTMENT STRATEGIES
Strategy Narrative [Text Block] rr_StrategyNarrativeTextBlock The Fund pursues its investment objective by primarily investing in U.S. Treasury securities, short-duration high-yield/high-risk debt, commodity-linked investments, and equity securities. The Fund’s investments in U.S. Treasury securities may also include Treasury Inflation-Protected Securities, also known as TIPS. As utilized by the Fund, each of these types of investments may be considered an “inflation-related investment,” which are those that may provide what is known as “real return,” or a rate of return above the rate of inflation over a full market cycle. Due to the nature of the securities in which the Fund invests, it may have relatively high portfolio turnover compared to other funds.

The Fund may invest up to 90% of its net assets in short-duration high-yield/high-risk debt securities. The Fund’s investments in short-duration high-yield/high-risk securities include debt rated below investment grade, also known as “junk” bonds. Securities rated below investment grade may include their unrated equivalents or other high-yielding securities the portfolio managers believe offer attractive risk/return characteristics. The Fund may also invest in certain investment grade debt instruments, including corporate bonds, government bonds, municipal bonds, commercial and residential mortgage-backed securities, zero-coupon bonds, and agency securities. The Fund may invest in foreign debt securities.

To seek exposure to the commodities markets, the Fund may invest in commodity-linked investments such as commodity-related exchange-traded funds (“ETFs”), commodity index-linked swap agreements, commodity options and futures, and options on futures that provide exposure to the investment returns of the commodities markets. The Fund may also invest in other commodity-linked derivative instruments, such as commodity-linked notes (“structured notes”).

The Fund’s investments in equity securities may include common stock, preferred stock, and convertible securities, all of which may include exposure to foreign markets. The Fund may invest in companies of any market capitalization. The Fund’s equity investments may also include securities of real estate-related companies, including, but not limited to, real estate investment trusts (“REITs”) and similar REIT-like entities, such as foreign entities that have REIT characteristics.

The Fund may also invest in derivative instruments (by taking long and/or short positions) for various purposes, including hedging by shorting interest rate futures against long positions in TIPS, using inflation index swaps to hedge against unexpected changes in the rate of inflation, using interest rate swaps to hedge against changes in interest rates, using currency swaps to adjust its currency exposure, to increase or decrease the Fund’s exposure to a particular market, to manage or adjust the risk profile of the Fund related to an investment, and to earn income and enhance returns.

The Fund may also use reverse repurchase agreements to generate income as part of its inflation-related strategies. Proceeds from reverse repurchase agreement transactions may be invested in other securities or instruments to attempt to increase the Fund’s investment return. The Fund may also invest in money market instruments, buy backs or dollar rolls, other securitized debt products, commercial loans, various when-issued securities, exchange-traded notes, and other investment companies.

In addition to considering economic factors such as the rate of inflation and the effect of interest rates on the Fund’s investments, the portfolio managers apply a “bottom up” approach in choosing investments. This means that the portfolio managers look at 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.

The Fund may lend portfolio securities on a short-term or long-term basis, in an amount equal to up to one-third of its total assets as determined at the time of the loan origination.
Risk [Heading] rr_RiskHeading PRINCIPAL INVESTMENT RISKS
Risk Narrative [Text Block] rr_RiskNarrativeTextBlock Although the Fund may be less volatile than funds that invest most of their assets in common stocks, the Fund’s returns and yields will vary, and you could lose money.

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. The Fund may be subject to heightened interest rate risk because the Federal Reserve has ended its monetary stimulus program known as quantitative easing. The conclusion of quantitative easing and/or rising interest rates may expose fixed-income markets to increased volatility and may reduce the liquidity of certain Fund investments. 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 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, 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. 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. Liquidity risk may be enhanced to the extent that the Fund invests in Rule 144A and restricted securities.

High-Yield/High-Risk Bond Risk. High-yield/high-risk bonds may be more sensitive than other types of bonds to economic changes, political changes, or adverse developments specific to the company that issued the bond, which may adversely affect their value. High-yield/high-risk bonds (or “junk” bonds) are bonds 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 bonds of similar quality. The value of lower quality bonds generally is more dependent on credit risk than investment grade bonds. Issuers of high-yield/high-risk bonds may not be as strong financially as those issuing bonds 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.

Sovereign Debt Risk. The Fund may invest in U.S. and non-U.S. government debt securities (“sovereign debt”). Investments in U.S. sovereign debt are considered low risk. However, investments in non-U.S. sovereign debt 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.

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.

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 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 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.

Inflation-Related Investment Risk. Inflation index swaps, inflation-linked bonds (including TIPS), and other inflation-linked securities are subject to inflation risk. A swap held long by the Fund can potentially lose value if the rate of inflation over the life of the swap is less than the fixed rate that the Fund agrees to pay at the initiation of the swap. Except for the Fund’s investments in TIPS, which are guaranteed as to principal by the U.S. Treasury, the inflation-adjusted principal value of inflation-linked bonds repaid at maturity may be less than the original principal. Because of their inflation-linked adjustment feature, inflation-linked bonds typically have lower yields than conventional fixed-rate securities. In the event of deflation, where prices decline over time, the principal and income of inflation-linked bonds will likely decline, resulting in losses to the Fund.

Commodity-Linked Investments Risk. The Fund may invest in various commodity-linked investments that provide exposure to the commodities markets. Such exposure may subject the Fund to greater volatility than investments in traditional securities. The value of a given commodity-linked derivative investment typically is based upon the price movements of a physical commodity (such as heating oil, livestock, or agricultural products), a commodity futures contract or commodity index, or some other readily measurable economic variable. The value of commodity-linked derivative instruments may therefore be affected by changes in overall market movements, volatility of the underlying benchmark, changes in interest rates, or other factors affecting a particular industry or commodity such as drought, floods, weather, livestock disease, embargoes, tariffs, and international economic, political, and regulatory developments.

Derivatives Risk. Derivatives can be highly volatile and involve risks in addition to the risks of the underlying referenced securities. 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.

Counterparty Risk. Certain derivative and “over-the-counter” instruments, such as swaps and forwards, are subject to the risk that the other party to a contract will not fulfill its contractual obligations.

Exchange-Traded Funds Risk. The Fund may invest in ETFs to gain exposure to a particular portion of the market. ETFs are typically open-end investment companies, which may be actively managed or passively managed, that generally seek to track the performance of a specific index. ETFs are traded on a national securities exchange at market prices that may vary from the net asset value of their underlying investments. Accordingly, there may be times when an ETF trades at a premium or discount. When the Fund invests in an ETF, in addition to directly bearing the expenses associated with its own operations, it will bear a pro rata portion of the ETF’s expenses. The Fund is also subject to the risks associated with the securities in which the ETF invests.

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.

Reverse Repurchase Agreement Risk. Reverse repurchase agreements involve leverage risk, counterparty risk, and the risk that the value of securities that the Fund is obligated to repurchase under the agreement may decline below the repurchase price. When the Fund invests reverse repurchase transaction proceeds, the Fund is at risk for any fluctuations in the value of securities in which the proceeds are invested. To the extent the Fund uses reverse repurchase agreements, the value of an investment in the Fund may be more volatile, and such transactions may increase the Fund’s overall investment exposure. Additionally, interest expenses related to reverse repurchase transactions could exceed the rate of return on debt obligations and other investments held by the Fund, thereby reducing returns to shareholders.

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.

Securities Lending Risk. The Fund may seek to earn additional income through lending its securities to certain qualified broker-dealers and institutions. There is the risk that when portfolio securities are lent, the securities may not be returned on a timely basis, and the Fund may experience delays and costs in recovering the security or gaining access to the collateral provided to the Fund to collateralize the loan. If the Fund is unable to recover a security on loan, the Fund may use the collateral to purchase replacement securities in the market. There is a risk that the value of the collateral could decrease below the cost of the replacement security by the time the replacement investment is made, resulting in a loss to the Fund.

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 Although the Fund may be less volatile than funds that invest most of their assets in common stocks, the Fund’s returns and yields will vary, and you could lose money.
Risk Not Insured Depository Institution [Text] rr_RiskNotInsuredDepositoryInstitution 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.
Bar Chart and Performance Table [Heading] rr_BarChartAndPerformanceTableHeading PERFORMANCE INFORMATION
Performance Narrative [Text Block] rr_PerformanceNarrativeTextBlock The following information provides some indication of the risks of investing in the Fund by showing how the Fund’s performance has varied over time. The bar chart depicts the change in performance from year to year during the periods indicated. The table compares the Fund’s average annual returns for the periods indicated to broad-based securities market indices. The indices are not actively managed and are not available for direct investment. 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 janus.com/allfunds or by calling 1-800-525-3713.
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.

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. The indices are not actively managed and are not available for direct investment. All figures assume reinvestment of dividends and distributions.
Performance Availability Phone [Text] rr_PerformanceAvailabilityPhone 1-800-525-3713
Performance Availability Website Address [Text] rr_PerformanceAvailabilityWebSiteAddress janus.com/allfunds
Performance Past Does Not Indicate Future [Text] rr_PerformancePastDoesNotIndicateFuture The Fund’s past performance (before and after taxes) does not necessarily indicate how it will perform in the future.
Bar Chart [Heading] rr_BarChartHeading
Annual Total Returns for Class D Shares (calendar year-end)
Bar Chart Closing [Text Block] rr_BarChartClosingTextBlock Best Quarter:  1st Quarter 2012  5.63%          Worst Quarter:  2nd Quarter 2012  −3.82%
Year to Date Return, Label rr_YearToDateReturnLabel The Fund’s year-to-date return as of the calendar quarter ended September 30, 2015 was 1.04%.
Performance Table Heading rr_PerformanceTableHeading Average Annual Total Returns (periods ended 12/31/14)
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 Explanation after Tax Higher rr_PerformanceTableExplanationAfterTaxHigher If the Fund incurs a loss, which generates a tax benefit, the Return After Taxes on Distributions and Sale of Fund Shares may exceed the Fund’s other return figures.
Performance Table Narrative rr_PerformanceTableNarrativeTextBlock The Barclays U.S. 1-5 Year TIPS Index (also known as Barclays 1-5 Year U.S. Inflation-Linked Treasury Index) measures the performance of U.S. Treasury Inflation Protected Securities (TIPS) with maturity between one and five years.

The Consumer Price Index +2% is a measure of the average change over time in the prices paid by urban consumers for the market basket of consumer goods and services plus 200 basis points.

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.
Performance Table Closing [Text Block] rr_PerformanceTableClosingTextBlock Updated performance information is available at janus.com/allfunds or by calling 1-800-525-3713.
Janus Real Return Fund | Class D Shares | Class D  
Risk/Return: rr_RiskReturnAbstract  
Operating Expenses Column [Text] rr_OperatingExpensesColumnName Class D
Management Fees rr_ManagementFeesOverAssets 0.55%
Other Expenses rr_OtherExpensesOverAssets 1.30%
Total Annual Fund Operating Expenses rr_ExpensesOverAssets 1.85% [1]
Fee Waiver rr_FeeWaiverOrReimbursementOverAssets 1.21% [1]
Total Annual Fund Operating Expenses After Fee Waiver rr_NetExpensesOverAssets 0.64% [1]
Expense Example, By Year, Column [Text] rr_ExpenseExampleByYearColumnName
Class D Shares
1 Year rr_ExpenseExampleYear01 $ 188
3 Years rr_ExpenseExampleYear03 582
5 Years rr_ExpenseExampleYear05 1,001
10 Years rr_ExpenseExampleYear10 $ 2,169
2012 rr_AnnualReturn2012 4.87%
2013 rr_AnnualReturn2013 2.53%
2014 rr_AnnualReturn2014 1.02%
Bar Chart, Year to Date Return, Date rr_BarChartYearToDateReturnDate Sep. 30, 2015
Bar Chart, Year to Date Return rr_BarChartYearToDateReturn 1.04%
Highest Quarterly Return, Label rr_HighestQuarterlyReturnLabel Best Quarter:
Highest Quarterly Return, Date rr_BarChartHighestQuarterlyReturnDate Mar. 31, 2012
Highest Quarterly Return rr_BarChartHighestQuarterlyReturn 5.63%
Lowest Quarterly Return, Label rr_LowestQuarterlyReturnLabel Worst Quarter:
Lowest Quarterly Return, Date rr_BarChartLowestQuarterlyReturnDate Jun. 30, 2012
Lowest Quarterly Return rr_BarChartLowestQuarterlyReturn (3.82%)
Janus Real Return Fund | Class D Shares | Return Before Taxes | Class D  
Risk/Return: rr_RiskReturnAbstract  
Column rr_AverageAnnualReturnColumnName Class D Shares
Label rr_AverageAnnualReturnLabel Return Before Taxes
1 Year rr_AverageAnnualReturnYear01 1.02%
Since Inception rr_AverageAnnualReturnSinceInception 0.86%
Inception Date rr_AverageAnnualReturnInceptionDate May 13, 2011
Janus Real Return Fund | Class D Shares | Return After Taxes on Distributions | Class D  
Risk/Return: rr_RiskReturnAbstract  
Column rr_AverageAnnualReturnColumnName Class D Shares
Label rr_AverageAnnualReturnLabel Return After Taxes on Distributions
1 Year rr_AverageAnnualReturnYear01 (0.48%)
Since Inception rr_AverageAnnualReturnSinceInception 0.15%
Inception Date rr_AverageAnnualReturnInceptionDate May 13, 2011
Janus Real Return Fund | Class D Shares | Return After Taxes on Distributions and Sale of Fund Shares | Class D  
Risk/Return: rr_RiskReturnAbstract  
Column rr_AverageAnnualReturnColumnName Class D Shares
Label rr_AverageAnnualReturnLabel Return After Taxes on Distributions and Sale of Fund Shares [2]
1 Year rr_AverageAnnualReturnYear01 0.60%
Since Inception rr_AverageAnnualReturnSinceInception 0.40%
Inception Date rr_AverageAnnualReturnInceptionDate May 13, 2011
Janus Real Return Fund | Class D Shares | Barclays U.S. 1-5 Year TIPS Index (reflects no deduction for expenses, fees, or taxes)  
Risk/Return: rr_RiskReturnAbstract  
Label rr_AverageAnnualReturnLabel Barclays U.S. 1-5 Year TIPS Index
1 Year rr_AverageAnnualReturnYear01 (1.13%)
Since Inception rr_AverageAnnualReturnSinceInception 0.23%
Inception Date rr_AverageAnnualReturnInceptionDate May 13, 2011
Janus Real Return Fund | Class D Shares | Consumer Price Index +2% (reflects no deduction for expenses, fees, or taxes)  
Risk/Return: rr_RiskReturnAbstract  
Label rr_AverageAnnualReturnLabel Consumer Price Index +2%
1 Year rr_AverageAnnualReturnYear01 2.76%
Since Inception rr_AverageAnnualReturnSinceInception 3.07%
Inception Date rr_AverageAnnualReturnInceptionDate May 13, 2011
[1] Janus Capital has contractually agreed to waive its investment advisory fee and/or reimburse Fund expenses to the extent that the Fund’s total annual fund operating expenses (excluding administrative services fees payable pursuant to the Transfer Agency Agreement, brokerage commissions, interest, dividends, taxes, acquired fund fees and expenses, and extraordinary expenses) exceed 0.47% until at least November 1, 2016. The contractual waiver may be terminated or modified prior to this date only at the discretion of the Board of Trustees.
[2] If the Fund incurs a loss, which generates a tax benefit, the Return After Taxes on Distributions and Sale of Fund Shares may exceed the Fund’s other return figures.