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, including the maximum amount of the capital protection fee, without waivers, remain the same. Although your actual costs may be higher or lower, based on these assumptions your costs would be:

Expense Example, No Redemption:

rr_ExpenseExampleNoRedemptionAbstract

Portfolio Turnover:

jif277751_PortfolioTurnoverAltAbstract

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.

Strategy [Heading]

rr_StrategyHeading

PRINCIPAL INVESTMENT STRATEGIES

Principal Investment Risks

jif277751_PrincipalInvestmentRisksAbstract

Risk Narrative [Text Block]

rr_RiskNarrativeTextBlock

The biggest risk is that the Fund’s returns will vary, and you could lose money, despite the Capital Protection Agreement. Common stocks tend to be more volatile than many other investment choices. Because the NAV per share for a share class is protected to at least 80%, and not 100%, of its highest attained NAV since the inception of the share class (as reduced to account for dividends, distributions, any extraordinary expenses, and certain extraordinary items), it is possible that in the event that equity markets fall, you could lose money, even if the Protection is triggered. In addition, if the Capital Protection Agreement does not work as intended or has been terminated, you could lose money. Because the Protected NAV is reduced by dividends, distributions, any extraordinary expenses, and certain extraordinary items, the amount of Protection could be less than 80% of the highest attained NAV for your class of shares, meaning the Protected NAV does not become a static number that only increases. To the extent that the protected amount owed to the Fund exceeds the Maximum Settlement Amount ($500 million), none of the Fund, Janus Capital, any affiliate thereof, or any company offering the shares will cover any shortfall amount, so you could lose money including amounts that would have otherwise been protected.

The Protected NAV for each share class will be posted on the Janus websites at janus.com/advisor/mutual-funds, or janus.com/allfunds for shareholders of Class D Shares. Any change to the Protected NAV is expected to be updated within one business day. Because any one share class falling below its Protected NAV can alone trigger the Protection and liquidation of the Fund, shareholders should review the Protected NAV for each share class prior to purchasing shares of this Fund, keeping in mind that each share class has different fees and expenses that impact the NAV. Shareholders considering an investment in Class A Shares should pay particular attention to the Protected NAV of each share class as part of their investment decision given that Class A Shares have an upfront sales load that once paid, is not reimbursed when the Fund liquidates.

Allocation Risk. Because there are risk parameters within which the portfolio manager must manage the Fund’s assets in order to maintain the Protection, the Fund’s ability to take certain investment actions that the portfolio manager might otherwise take may be limited. More specifically, complying with the provisions of the Capital Protection Agreement may impact the Fund’s allocation of assets to and within the Equity Component during the life of the Fund, may not allow the Fund to be fully invested in the Equity Component, and/or may affect the portfolio manager’s ability to respond to changing equity market conditions. This could limit the Fund’s ability to capture certain market gains when the allocations are more heavily weighted to the Protection Component. Conversely, as equity markets are rising or displaying signs of relative stability, the Fund may have more of the portfolio weighted towards assets considered to have higher risk which could increase the potential for loss of return for the Fund. Generally, the risk parameters may lead the portfolio manager to take certain investment actions that would not otherwise be taken when allocating the Fund’s assets between and within the Equity Component and the Protection Component. This allocation process can have an adverse effect on the performance of the Fund, especially during periods of increased equity market volatility. The risk allocation methodology is designed so that the NAV of each share class does not fall below its Protected NAV and, if successful, protection payments are not triggered. It is possible, however, that the risk allocation methodology may not work as designed or intended and may cause the Fund to trigger the Protection, resulting in the termination of the Fund. In addition, the allocation of the Fund’s assets between and within the Equity Component and the Protection Component will likely result in a high portfolio turnover rate and additional transaction costs, such as brokerage commissions, which can impact the Fund’s returns. Because the portfolio manager allocates the Fund’s assets between and within the Equity Component and Protection Component daily according to a risk allocation methodology, there is the risk that a sudden intraday market drop may occur before the Fund’s Equity Component exposure can be reduced. Additionally, if the Fund fails to allocate its assets according to the risk allocation methodology, the Capital Protection Provider will have the option to terminate the Capital Protection Agreement, resulting in the Fund allocating 100% of its assets solely to cash and the liquidation of the Fund. Under these circumstances, the Capital Protection Provider will pay any amounts it is obligated to pay to the Fund.

Market Underperformance Risk. The Fund’s use of the risk allocation methodology and the resulting allocation between and within the Equity Component and the Protection Component may cause the Fund to underperform its primary benchmark and/or other similarly situated growth funds. This underperformance may be a result of the portfolio manager’s inability to reallocate Fund assets to respond to rising equity market conditions as quickly as another fund that invests primarily in equity securities, including non-U.S. securities. In addition, to maintain compliance with the risk parameters, the Fund may need to liquidate a position, or forego an investment that could have otherwise contributed to Fund performance. Under certain circumstances, the Capital Protection Agreement may require that all of the Fund’s assets be fully allocated to the Protection Component, thus limiting the upside potential for Fund returns during this period. The use of the risk allocation methodology may also impact the Fund’s performance in the event that it does not work as intended, potentially subjecting the Fund to additional expenses as a result of increased trading or allocating a larger portion of the Fund’s assets than necessary to either the Equity Component or Protection Component. Because the Fund may reallocate its assets between and within the Equity Component and the Protection Component as frequently as daily, the Fund’s reallocation will likely cause it to experience an increase in its portfolio turnover rate resulting in higher costs, which may have a negative effect on the Fund’s performance, particularly during periods of relative instability in equity markets. The Fund’s payment of the capital protection fee to the Capital Protection Provider may also result in the Fund underperforming its primary benchmark and/or other similarly situated growth funds that do not pay a protection fee.

Capital Protection Termination Risk. There is a risk that the Protection could terminate without any obligation of the Capital Protection Provider or the Parent Guarantor to make payment to the Fund. The terms and conditions of the Capital Protection Agreement are designed to protect against certain market risks inherent in any equity investment. It does not protect against certain actions or omissions that constitute gross negligence, fraud, bad faith, willful misconduct, or a criminal act on the part of the Fund, Janus Capital or certain key employees of Janus Capital, or the Fund’s custodian, that negatively impacts a share class’ NAV. Such events will result in the termination of the Protection without any obligation by the Capital Protection Provider, and therefore by the Parent Guarantor, to make any payment to the Fund. The Fund will liquidate in these events, and shareholders will not receive the Protected NAV but will instead receive the Fund’s then-current NAV at the time their shares are redeemed, which may be lower than the Protected NAV and lower than the price per share of the shareholder’s initial investment. None of the Fund, Janus Capital, any affiliate thereof, or any company offering the shares is obligated to make any payment to the Fund or cover any shortfall. Therefore, in the event that the Protection is terminated as a result of such events, you could lose money as a result of the Fund losing the Protection under the Capital Protection Agreement, including amounts that would have otherwise been protected. This means that you could receive less than 80% of your investment and will not be reimbursed for any amounts paid under the Capital Protection Agreement.

Early Termination Events Risk. While the Capital Protection Agreement has an initial 10-year term that may be extended, there is a risk that the Capital Protection Agreement could terminate earlier under various scenarios at the option of the Capital Protection Provider, which are considered Early Termination Events. In such events, the Capital Protection Provider will be obligated to make the payment of the Settlement Amount, if due, to the Fund and the Fund will liquidate. Shareholders receive the higher of their Protected NAV or the then-current NAV for their share class, which will include any Settlement Amount due to the Fund. Examples of “Early Termination Events” include, but are not limited to (1) if the Fund, Janus Capital, or the Fund’s custodian, fails to comply with certain terms and conditions of the Capital Protection Agreement, including the failure to reallocate Fund assets when such assets fall outside the specified risk parameters, or (2) if the aggregate value of the Fund’s shares outstanding results in the Protection exceeding the Maximum Settlement Amount. The Fund is also expected to liquidate and the Capital Protection Agreement will terminate if, pursuant to the terms of the Capital Protection Agreement, the Protection is triggered. In addition, to the extent that the introduction of laws or a change of law, in each case, not known as of the date of the Capital Protection Agreement, results in a new or increased cost of capital or collateral for the Capital Protection Provider or its parent company, the Fund’s Board of Trustees will make a determination whether to approve the Fund paying such increased costs to the Capital Protection Provider or to terminate the Capital Protection Agreement. Only shareholders who hold their shares on the Termination Date are entitled to receive the Protected NAV from the Fund. Shareholders who redeem prior to the Termination Date receive the then-current NAV which will be higher than the Protected NAV for their share class and will not include any payment of the Protection.

Maximum Settlement Amount Risk. The Capital Protection Agreement currently covers the outstanding shares of each class of shares offered by the Fund having an aggregate protected amount up to an initial value of $500 million. If the Maximum Settlement Amount exceeds $500 million without any additional coverage being extended to the Fund, the Capital Protection Provider will not be liable for any Settlement Amount payment in excess of $500 million. None of the Fund, Janus Capital, any affiliate thereof, or any company offering the shares will be responsible for any portion of the Settlement Amount, including any amounts which may exceed the Maximum Settlement Amount. Therefore, although the Protection applies, you could lose money to the extent the Aggregate Shortfall Amount exceeds the Maximum Settlement Amount including amounts that would have otherwise been protected. This means that you could receive less than 80% of your investment. In any event, as the Fund’s assets grow, the Fund intends to take such actions as may be deemed necessary, including limiting shareholder purchases, to limit the Aggregate Shortfall Amount to a level so that it does not exceed the Maximum Settlement Amount, but there is no guarantee that such efforts will be successful. There is no guarantee that the Capital Protection Provider will agree to extend coverage beyond $500 million.

Liquidation Risk. Although the risk allocation methodology is designed so that the NAV of each share class does not fall below its Protected NAV, there is the possibility that the risk allocation methodology may not work as designed or redemptions, particularly a large redemption, may impact the allocation process, and the NAV of any share class falls below its Protected NAV. If this happens, it is expected that the Fund will receive payment of the Settlement Amount from the Capital Protection Provider, if due, and liquidate as soon as possible following the event. The NAV of one share class falling below its Protected NAV will result in the Protection being triggered and, as a result, the liquidation of the entire Fund, even though the NAV of one or more other share classes remains at or above its Protected NAV. Other events described in this Prospectus may, at the discretion of the Fund or Capital Protection Provider, as applicable, also terminate the Capital Protection Agreement resulting in payment of the Settlement Amount and liquidation of the Fund. In the event the Protection is triggered and the Fund begins the liquidation process, no other purchases will be permitted, and the payment of redemption proceeds will be suspended, likely from the day the Protection is triggered; shareholders receive the higher of their Protected NAV or the then-current NAV for their share class, which will include any Settlement Amount due to the Fund. Redemptions are taxable events. This Prospectus serves as advance notice to shareholders of any rejection of purchases, suspension of the payment of redemption proceeds, and liquidation of the Fund. In the event that the Capital Protection Agreement is terminated and the Fund begins the liquidation process, Janus Capital will make such information available at janus.com/advisor/mutual-funds, or janus.com/allfunds for shareholders of Class D Shares. Notice of the Fund liquidation will otherwise be made when you receive your redemption proceeds. For illustrative purposes to understand a scenario where the Protection is triggered and the Fund proceeds to liquidation, see below:

Protected NAV across all share classes is $10.00 –

• Day 1 (Tuesday) – One share class NAV is $9.00 and each other share class’ NAV is $11.00. Purchases are rejected and the payment of redemptions is suspended as the Fund proceeds to liquidation since there is at least one share class’ NAV that is below its Protected NAV.

• Day 7 (Monday) – Fund receives Protection payment from the Capital Protection Provider, and the Fund liquidates and terminates and pays out a $10.00 Protected NAV to the share class that had a $9.00 NAV. All other share classes are redeemed at $11.00 NAV, plus the Settlement Amount distributed pro rata to their share class.

Opportunity Cost Risk. It is possible that under the terms of the Capital Protection Agreement, the Fund’s allocation to the Equity Component could drop to a low level or be eliminated altogether, especially during periods of heightened volatility in equity markets. This would reduce the Fund’s ability to participate in upward equity market movements, and therefore, represents loss of opportunity compared to a fund that is fully invested in equity securities.

Counterparty Risk (Capital Protection Provider and its Parent Company). A shareholder’s ability to receive the Protected NAV from the Fund is dependent on the Fund’s ability to collect the Settlement Amount from the Capital Protection Provider pursuant to the terms of the Capital Protection Agreement or from the Capital Protection Provider’s parent under a separate parent guaranty. Fund transactions involving a counterparty, such as the Capital Protection Provider, are subject to the risk that the counterparty or a third party will not fulfill its obligation to the Fund (“counterparty risk”). Counterparty risk may arise because of the counterparty’s financial condition (i.e., financial difficulties, bankruptcy, or insolvency), market activities and developments, or other reasons, whether foreseen or not. As such, the Fund’s ability to benefit from the Protection may depend on the Capital Protection Provider’s, as well as its parent company’s, financial condition. As an added measure of protection, BNP Paribas, the parent company of the Capital Protection Provider, has issued an absolute, irrevocable and continuing guaranty pursuant to which it guarantees any and all financial obligations of the Capital Protection Provider under the Capital Protection Agreement. There is, however, a risk that the Capital Protection Provider’s parent company may not fulfill its obligations under the guaranty it has issued.

Foreign Exposure Risk. The Fund normally has significant exposure to foreign markets, including 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. 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 mentioned above 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, seizure, nationalization, 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 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 specialized risks.

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 investment personnel’s 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. The Fund’s use of the risk allocation methodology is intended to protect against significant downward movement of the NAV per share for a share class, particularly in times of heightened volatility in the equity markets, but the methodology may not protect the Fund if equity markets take a sudden and/or significant fall.

Growth Securities Risk. The Fund invests in companies after assessing their growth potential. Securities of companies perceived to be “growth” companies may be more volatile than other stocks and may involve special risks. If the Research Team’s or portfolio manager’s perception of a company’s growth potential is not realized, the securities purchased may not perform as expected, reducing the Fund’s return. In addition, because different types of stocks tend to shift in and out of favor depending on market and economic conditions, “growth” stocks may perform differently from the market as a whole and other types of securities.

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 can be substantially greater than the derivative’s original cost, and can therefore involve 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 to the Fund. If the counterparty to a derivative transaction defaults, such as the Capital Protection Provider or Parent Guarantor, 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.

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. The risk allocation methodology utilized by the Fund will likely increase the level of portfolio turnover.

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 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 One Year or Less [Text]

rr_PerformanceOneYearOrLess

The Fund does not have a full calendar year of operations.

SHAREHOLDER FEES

rr_ShareholderFeesAbstract

Maximum Sales Charge (load) Imposed on Purchases (as a percentage of offering price)

rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice

5.75%

ANNUAL FUND OPERATING EXPENSES

rr_OperatingExpensesAbstract

Management Fees

rr_ManagementFeesOverAssets

0.64%

Other Expenses

rr_OtherExpensesOverAssets

1.30%

^[1]

Remaining Other Expenses

rr_Component2OtherExpensesOverAssets

0.55%

Fee Waiver

rr_FeeWaiverOrReimbursementOverAssets

0.18%

^[2]

EXAMPLE:

rr_ExpenseExampleAbstract

1 Year

rr_ExpenseExampleYear01

784

Expense Example, No Redemption:

rr_ExpenseExampleNoRedemptionAbstract

1 Year

rr_ExpenseExampleNoRedemptionYear01

784

Shareholder Fees Column [Text]

rr_ShareholderFeesColumnName

Class C

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

Distribution/Service (12b-1) Fees

rr_DistributionAndService12b1FeesOverAssets

1.00%

Capital Protection Fee

rr_Component1OtherExpensesOverAssets

0.75%

Total Annual Fund Operating Expenses

rr_ExpensesOverAssets

2.96%

^[2]

Net Annual Fund Operating Expenses After Fee Waiver

rr_NetExpensesOverAssets

2.76%

^[2]

Expense Example, By Year, Column [Text]

rr_ExpenseExampleByYearColumnName

Class C Shares

3 Years

rr_ExpenseExampleYear03

915

Expense Example, No Redemption, By Year, Column [Text]

rr_ExpenseExampleNoRedemptionByYearColumnName

Class C Shares

3 Years

rr_ExpenseExampleNoRedemptionYear03

915

SHAREHOLDER FEES

rr_ShareholderFeesAbstract

Maximum Sales Charge (load) Imposed on Purchases (as a percentage of offering price)

rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice

none

ANNUAL FUND OPERATING EXPENSES

rr_OperatingExpensesAbstract

Management Fees

rr_ManagementFeesOverAssets

0.64%

Other Expenses

rr_OtherExpensesOverAssets

1.45%

^[1]

Remaining Other Expenses

rr_Component2OtherExpensesOverAssets

0.70%

Fee Waiver

rr_FeeWaiverOrReimbursementOverAssets

0.08%

^[2]

EXAMPLE:

rr_ExpenseExampleAbstract

1 Year

rr_ExpenseExampleYear01

237

Expense Example, No Redemption:

rr_ExpenseExampleNoRedemptionAbstract

1 Year

rr_ExpenseExampleNoRedemptionYear01

237

Shareholder Fees Column [Text]

rr_ShareholderFeesColumnName

Class I

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

Distribution/Service (12b-1) Fees

rr_DistributionAndService12b1FeesOverAssets

none

Capital Protection Fee

rr_Component1OtherExpensesOverAssets

0.75%

Total Annual Fund Operating Expenses

rr_ExpensesOverAssets

1.91%

^[2]

Net Annual Fund Operating Expenses After Fee Waiver

rr_NetExpensesOverAssets

1.76%

^[2]

Expense Example, By Year, Column [Text]

rr_ExpenseExampleByYearColumnName

Class I Shares

3 Years

rr_ExpenseExampleYear03

600

Expense Example, No Redemption, By Year, Column [Text]

rr_ExpenseExampleNoRedemptionByYearColumnName

Class I Shares

3 Years

rr_ExpenseExampleNoRedemptionYear03

600

SHAREHOLDER FEES

rr_ShareholderFeesAbstract

Maximum Sales Charge (load) Imposed on Purchases (as a percentage of offering price)

rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice

none

ANNUAL FUND OPERATING EXPENSES

rr_OperatingExpensesAbstract

Management Fees

rr_ManagementFeesOverAssets

0.64%

Other Expenses

rr_OtherExpensesOverAssets

1.45%

^[1]

Remaining Other Expenses

rr_Component2OtherExpensesOverAssets

0.70%

Fee Waiver

rr_FeeWaiverOrReimbursementOverAssets

0.08%

^[2]

EXAMPLE:

rr_ExpenseExampleAbstract

1 Year

rr_ExpenseExampleYear01

212

Expense Example, No Redemption:

rr_ExpenseExampleNoRedemptionAbstract

1 Year

rr_ExpenseExampleNoRedemptionYear01

212

Risk/Return [Heading]

rr_RiskReturnHeading

FUND SUMMARY Janus Protected Series – Global

Objective, Primary [Text Block]

rr_ObjectivePrimaryTextBlock

Janus Protected Series – Global seeks long-term growth of capital and capital preservation.

Expense [Heading]

rr_ExpenseHeading

FEES AND EXPENSES OF THE FUND

ANNUAL FUND OPERATING EXPENSES

rr_OperatingExpensesAbstract

Other Expenses, New Fund, Based on Estimates [Text]

rr_OtherExpensesNewFundBasedOnEstimates

Since the Fund is new, Other Expenses are based on the estimated expenses that the Fund expects to incur in its initial fiscal period.

EXAMPLE:

rr_ExpenseExampleAbstract

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.

Portfolio Turnover:

jif277751_PortfolioTurnoverAltAbstract

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.

Strategy [Heading]

rr_StrategyHeading

PRINCIPAL INVESTMENT STRATEGIES

Principal Investment Risks

jif277751_PrincipalInvestmentRisksAbstract

Risk Narrative [Text Block]

rr_RiskNarrativeTextBlock

The biggest risk is that the Fund’s returns will vary, and you could lose money, despite the Capital Protection Agreement. Common stocks tend to be more volatile than many other investment choices. Because the NAV per share for a share class is protected to at least 80%, and not 100%, of its highest attained NAV since the inception of the share class (as reduced to account for dividends, distributions, any extraordinary expenses, and certain extraordinary items), it is possible that in the event that equity markets fall, you could lose money, even if the Protection is triggered. In addition, if the Capital Protection Agreement does not work as intended or has been terminated, you could lose money. Because the Protected NAV is reduced by dividends, distributions, any extraordinary expenses, and certain extraordinary items, the amount of Protection could be less than 80% of the highest attained NAV for your class of shares, meaning the Protected NAV does not become a static number that only increases. To the extent that the protected amount owed to the Fund exceeds the Maximum Settlement Amount ($500 million), none of the Fund, Janus Capital, any affiliate thereof, or any company offering the shares will cover any shortfall amount, so you could lose money including amounts that would have otherwise been protected.

The Protected NAV for each share class will be posted on the Janus websites at janus.com/allfunds, or janus.com/advisor/mutual-funds for share classes other than Class D Shares. Any change to the Protected NAV is expected to be updated within one business day. Because any one share class falling below its Protected NAV can alone trigger the Protection and liquidation of the Fund, shareholders should review the Protected NAV for each share class prior to purchasing shares of this Fund, keeping in mind that each share class has different fees and expenses that impact the NAV.

Allocation Risk. Because there are risk parameters within which the portfolio manager must manage the Fund’s assets in order to maintain the Protection, the Fund’s ability to take certain investment actions that the portfolio manager might otherwise take may be limited. More specifically, complying with the provisions of the Capital Protection Agreement may impact the Fund’s allocation of assets to and within the Equity Component during the life of the Fund, may not allow the Fund to be fully invested in the Equity Component, and/or may affect the portfolio manager’s ability to respond to changing equity market conditions. This could limit the Fund’s ability to capture certain market gains when the allocations are more heavily weighted to the Protection Component. Conversely, as equity markets are rising or displaying signs of relative stability, the Fund may have more of the portfolio weighted towards assets considered to have higher risk which could increase the potential for loss of return for the Fund. Generally, the risk parameters may lead the portfolio manager to take certain investment actions that would not otherwise be taken when allocating the Fund’s assets between and within the Equity Component and the Protection Component. This allocation process can have an adverse effect on the performance of the Fund, especially during periods of increased equity market volatility. The risk allocation methodology is designed so that the NAV of each share class does not fall below its Protected NAV and, if successful, protection payments are not triggered. It is possible, however, that the risk allocation methodology may not work as designed or intended and may cause the Fund to trigger the Protection, resulting in the termination of the Fund. In addition, the allocation of the Fund’s assets between and within the Equity Component and the Protection Component will likely result in a high portfolio turnover rate and additional transaction costs, such as brokerage commissions, which can impact the Fund’s returns. Because the portfolio manager allocates the Fund’s assets between and within the Equity Component and Protection Component daily according to a risk allocation methodology, there is the risk that a sudden intraday market drop may occur before the Fund’s Equity Component exposure can be reduced. Additionally, if the Fund fails to allocate its assets according to the risk allocation methodology, the Capital Protection Provider will have the option to terminate the Capital Protection Agreement, resulting in the Fund allocating 100% of its assets solely to cash and the liquidation of the Fund. Under these circumstances, the Capital Protection Provider will pay any amounts it is obligated to pay to the Fund.

Market Underperformance Risk. The Fund’s use of the risk allocation methodology and the resulting allocation between and within the Equity Component and the Protection Component may cause the Fund to underperform its primary benchmark and/or other similarly situated growth funds. This underperformance may be a result of the portfolio manager’s inability to reallocate Fund assets to respond to rising equity market conditions as quickly as another fund that invests primarily in equity securities, including non-U.S. securities. In addition, to maintain compliance with the risk parameters, the Fund may need to liquidate a position, or forego an investment that could have otherwise contributed to Fund performance. Under certain circumstances, the Capital Protection Agreement may require that all of the Fund’s assets be fully allocated to the Protection Component, thus limiting the upside potential for Fund returns during this period. The use of the risk allocation methodology may also impact the Fund’s performance in the event that it does not work as intended, potentially subjecting the Fund to additional expenses as a result of increased trading or allocating a larger portion of the Fund’s assets than necessary to either the Equity Component or Protection Component. Because the Fund may reallocate its assets between and within the Equity Component and the Protection Component as frequently as daily, the Fund’s reallocation will likely cause it to experience an increase in its portfolio turnover rate resulting in higher costs, which may have a negative effect on the Fund’s performance, particularly during periods of relative instability in equity markets. The Fund’s payment of the capital protection fee to the Capital Protection Provider may also result in the Fund underperforming its primary benchmark and/or other similarly situated growth funds that do not pay a protection fee.

Capital Protection Termination Risk. There is a risk that the Protection could terminate without any obligation of the Capital Protection Provider or the Parent Guarantor to make payment to the Fund. The terms and conditions of the Capital Protection Agreement are designed to protect against certain market risks inherent in any equity investment. It does not protect against certain actions or omissions that constitute gross negligence, fraud, bad faith, willful misconduct, or a criminal act on the part of the Fund, Janus Capital or certain key employees of Janus Capital, or the Fund’s custodian, that negatively impacts a share class’ NAV. Such events will result in the termination of the Protection without any obligation by the Capital Protection Provider, and therefore by the Parent Guarantor, to make any payment to the Fund. The Fund will liquidate in these events, and shareholders will not receive the Protected NAV but will instead receive the Fund’s then-current NAV at the time their shares are redeemed, which may be lower than the Protected NAV and lower than the price per share of the shareholder’s initial investment. None of the Fund, Janus Capital, any affiliate thereof, or any company offering the shares is obligated to make any payment to the Fund or cover any shortfall. Therefore, in the event that the Protection is terminated as a result of such events, you could lose money as a result of the Fund losing the Protection under the Capital Protection Agreement, including amounts that would have otherwise been protected. This means that you could receive less than 80% of your investment and will not be reimbursed for any amounts paid under the Capital Protection Agreement.

Early Termination Events Risk. While the Capital Protection Agreement has an initial 10-year term that may be extended, there is a risk that the Capital Protection Agreement could terminate earlier under various scenarios at the option of the Capital Protection Provider, which are considered Early Termination Events. In such events, the Capital Protection Provider will be obligated to make the payment of the Settlement Amount, if due, to the Fund and the Fund will liquidate. Shareholders receive the higher of their Protected NAV or the then-current NAV for their share class, which will include any Settlement Amount due to the Fund. Examples of “Early Termination Events” include, but are not limited to (1) if the Fund, Janus Capital, or the Fund’s custodian, fails to comply with certain terms and conditions of the Capital Protection Agreement, including the failure to reallocate Fund assets when such assets fall outside the specified risk parameters, or (2) if the aggregate value of the Fund’s shares outstanding results in the Protection exceeding the Maximum Settlement Amount. The Fund is also expected to liquidate and the Capital Protection Agreement will terminate if, pursuant to the terms of the Capital Protection Agreement, the Protection is triggered. In addition, to the extent that the introduction of laws or a change of law, in each case, not known as of the date of the Capital Protection Agreement, results in a new or increased cost of capital or collateral for the Capital Protection Provider or its parent company, the Fund’s Board of Trustees will make a determination whether to approve the Fund paying such increased costs to the Capital Protection Provider or to terminate the Capital Protection Agreement. Only shareholders who hold their shares on the Termination Date are entitled to receive the Protected NAV from the Fund. Shareholders who redeem prior to the Termination Date receive the then-current NAV which will be higher than the Protected NAV for their share class and will not include any payment of the Protection.

Maximum Settlement Amount Risk. The Capital Protection Agreement currently covers the outstanding shares of each class of shares offered by the Fund having an aggregate protected amount up to an initial value of $500 million. If the Maximum Settlement Amount exceeds $500 million without any additional coverage being extended to the Fund, the Capital Protection Provider will not be liable for any Settlement Amount payment in excess of $500 million. None of the Fund, Janus Capital, any affiliate thereof, or any company offering the shares will be responsible for any portion of the Settlement Amount, including any amounts which may exceed the Maximum Settlement Amount. Therefore, although the Protection applies, you could lose money to the extent the Aggregate Shortfall Amount exceeds the Maximum Settlement Amount including amounts that would have otherwise been protected. This means that you could receive less than 80% of your investment. In any event, as the Fund’s assets grow, the Fund intends to take such actions as may be deemed necessary, including limiting shareholder purchases, to limit the Aggregate Shortfall Amount to a level so that it does not exceed the Maximum Settlement Amount, but there is no guarantee that such efforts will be successful. There is no guarantee that the Capital Protection Provider will agree to extend coverage beyond $500 million.

Liquidation Risk. Although the risk allocation methodology is designed so that the NAV of each share class does not fall below its Protected NAV, there is the possibility that the risk allocation methodology may not work as designed or redemptions, particularly a large redemption, may impact the allocation process, and the NAV of any share class falls below its Protected NAV. If this happens, it is expected that the Fund will receive payment of the Settlement Amount from the Capital Protection Provider, if due, and liquidate as soon as possible following the event. The NAV of one share class falling below its Protected NAV will result in the Protection being triggered and, as a result, the liquidation of the entire Fund, even though the NAV of one or more other share classes remains at or above its Protected NAV. Other events described in this Prospectus may, at the discretion of the Fund or Capital Protection Provider, as applicable, also terminate the Capital Protection Agreement resulting in payment of the Settlement Amount and liquidation of the Fund. In the event the Protection is triggered and the Fund begins the liquidation process, no other purchases will be permitted, and the payment of redemption proceeds will be suspended, likely from the day the Protection is triggered; shareholders receive the higher of their Protected NAV or the then-current NAV for their share class, which will include any Settlement Amount due to the Fund. Redemptions are taxable events. This Prospectus serves as advance notice to shareholders of any rejection of purchases, suspension of the payment of redemption proceeds, and liquidation of the Fund. In the event that the Capital Protection Agreement is terminated and the Fund begins the liquidation process, Janus Capital will make such information available at janus.com/allfunds, or janus.com/advisor/mutual-funds for share classes other than Class D Shares. Notice of the Fund liquidation will otherwise be made when you receive your redemption proceeds. For illustrative purposes to understand a scenario where the Protection is triggered and the Fund proceeds to liquidation, see below: