XML 39 R41.htm IDEA: XBRL DOCUMENT v3.20.1
Label Element Value
MainStay Candriam Emerging Markets Debt Fund  
Risk/Return: rr_RiskReturnAbstract  
Risk/Return [Heading] rr_RiskReturnHeading MainStay Candriam Emerging Markets Debt Fund (formerly known as MainStay MacKay Emerging Markets Debt Fund)
Objective [Heading] rr_ObjectiveHeading Investment Objective
Objective, Primary [Text Block] rr_ObjectivePrimaryTextBlock

The Fund seeks total return.
Expense [Heading] rr_ExpenseHeading Fees and Expenses of the Fund
Expense Narrative [Text Block] rr_ExpenseNarrativeTextBlock

The table below describes the fees and expenses that you may pay if you buy and hold shares of the Fund. You may be required to pay a commission or other transaction charge to your financial intermediary for effecting transactions in a class of shares of the Fund that has no initial sales charge, contingent deferred sales charge, or other asset-based fee for sales or distribution, such as Class I or Class R6 shares. These commissions are not reflected in the fee and expense table or expense example below. 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 MainStay Funds. This amount may vary depending on the MainStay Fund in which you invest. In addition, different financial intermediary firms and financial professionals may impose different sales loads and waivers. More information about these and other discounts or waivers is available from your financial professional, in the "Information on Sales Charges" section starting on page 130 of the Prospectus and Appendix A – Intermediary-Specific Sales Charge Waivers and Discounts, and in the "Alternative Sales Arrangements" section on page 123 of the Statement of Additional Information.

Shareholder Fees Caption [Text] rr_ShareholderFeesCaption Shareholder Fees (fees paid directly from your investment)
Operating Expenses Caption [Text] rr_OperatingExpensesCaption Annual Fund Operating Expenses (expenses that you pay each year as a percentage of the value of your investment)
Fee Waiver or Reimbursement over Assets, Date of Termination rr_FeeWaiverOrReimbursementOverAssetsDateOfTermination Feb. 28, 2021
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 102% of the average value of its portfolio.

Portfolio Turnover, Rate rr_PortfolioTurnoverRate 102.00%
Expense Breakpoint Discounts [Text] rr_ExpenseBreakpointDiscounts 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 MainStay Funds.
Expense Breakpoint, Minimum Investment Required [Amount] rr_ExpenseBreakpointMinimumInvestmentRequiredAmount $ 50,000
Expenses Restated to Reflect Current [Text] rr_ExpensesRestatedToReflectCurrent Restated to reflect the elimination of the Fund’s fund accounting service fee.
Expense Example [Heading] rr_ExpenseExampleHeading Example
Expense Example Narrative [Text Block] rr_ExpenseExampleNarrativeTextBlock

The Example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds. The Example assumes that you invest $10,000 in the Fund for the time periods indicated whether or not you redeem all of your shares at the end of those periods (except as indicated with respect to Class B and Class C shares). The Example reflects Class B shares converting into Investor Class shares in years 9-10; fees could be lower if you are eligible to convert to Class A shares instead. The Example also assumes that your investment has a 5% return each year and that the Fund's operating expenses remain the same. The Example reflects the contractual fee waiver and/or expense reimbursement arrangement, if applicable, for the current duration of the arrangement only. Although your actual costs may be higher or lower, based on these assumptions your costs would be:
Expense Example by, Year, Caption [Text] rr_ExpenseExampleByYearCaption Assuming redemption at end of period
Expense Example, No Redemption, By Year, Caption [Text] rr_ExpenseExampleNoRedemptionByYearCaption Assuming no redemption
Strategy [Heading] rr_StrategyHeading Principal Investment Strategies
Strategy Narrative [Text Block] rr_StrategyNarrativeTextBlock

Under normal circumstances, the Fund invests at least 80% of its assets (net assets plus any borrowings for investment purposes) in fixed income securities of issuers in emerging markets. Candriam Luxembourg S.C.A., the Fund’s Subadvisor, has discretion to determine the countries considered to be emerging market countries, including taking into consideration a variety of factors such as the development of a country’s financial and capital markets and inclusion in an index, such as the J.P. Morgan Emerging Market Bond Index, considered by the Subadvisor to be representative of emerging markets.


The securities in which the Fund invests may be denominated in foreign currency. The debt securities in which the Fund invests may consist of securities that are rated below investment grade. Below investment grade securities are generally securities that receive low ratings from a nationally recognized statistical rating organization (“NRSRO”) (such as securities rated lower than BBB- and Baa3), or if unrated, are deemed to be of comparable quality by the Subadvisor. Securities rated below investment grade by a NRSRO are commonly referred to as “high yield securities” or “junk bonds.” If NRSROs assign different ratings to the same security, the Fund will use the higher rating for purposes of determining the security's credit quality. The Fund may invest in fixed income securities of any duration or maturity.


The Fund's principal investments include sovereign, quasi-sovereign and corporate Eurobonds. The Fund may invest in floating rate notes and inverse floating rate notes. The Fund may also invest in derivative instruments, such as forward commitments, futures, options and swap agreements to try to enhance returns or reduce the risk of loss by hedging certain of its holdings. The Fund may invest up to 20% of its total assets in swaps, including credit default swaps and credit default swap indices. The Fund may buy and sell currency on a spot basis, buy foreign currency options, and enter into foreign currency forward contracts. These techniques may be used for any purpose, including to seek to increase the Fund's return.


Investment Process: The Subadvisor identifies investment opportunities by deploying a relative value focused investment approach. The approach consists of three primary layers of analysis. The first layer assesses medium-term sovereign creditworthiness and sets up the basis for identifying the second and third layer investment opportunities, which are relative country (second layer) and instrument (third layer) investment opportunities.


The Subadvisor also considers key fundamental macro-economic drivers such as growth and inflation dynamics, internal and external imbalances as well as structural reform and political risk trends. The investment approach is aware of environmental, social and governance (“ESG”) risks as ESG factors are explicitly integrated in the sovereign creditworthiness analysis and may limit exposure to industries which do not satisfy the Subadvisor’s ESG criteria. To this end, the Subadvisor may also give consideration to ESG factors such as sector, country, currency, region, number of securities, certain types of extractive industries, tobacco-related industries and industries related to chemical, biological or white phosphorus weapons.


The Subadvisor may sell a security if it believes the security will no longer contribute to meeting the investment objective of the Fund.
Risk [Heading] rr_RiskHeading Principal Risks
Risk Narrative [Text Block] rr_RiskNarrativeTextBlock

You can lose money by investing in the Fund. An investment in the Fund is not a bank deposit and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other governmental agency. The investments selected by the Subadvisor may underperform the market in which the Fund invests or other investments. The Fund may receive large purchase or redemption orders which may have adverse effects on performance if the Fund were required to sell securities, invest cash or hold a relatively large amount of cash at times when it would not otherwise do so.


The principal risks of investing in the Fund are summarized below.


Market Risk: The value of the Fund’s investments may fluctuate because of changes in the markets in which the Fund invests, which could cause the Fund to underperform other funds with similar investment objectives and strategies. Such changes may be rapid and unpredictable. From time to time, markets may experience periods of stress for potentially prolonged periods that may result in: (i) increased market volatility; (ii) reduced market liquidity; and (iii) increased redemptions of Fund shares. Such conditions may add significantly to the risk of volatility in the net asset value of the Fund's shares.


Portfolio Management Risk: The investment strategies, practices and risk analyses used by the Subadvisor may not produce the desired results. In addition, the Fund may not achieve its investment objective, including during periods in which the Subadvisor takes temporary positions in response to unusual or adverse market, economic or political conditions, or other unusual or abnormal circumstances. The Subadvisor may give consideration to certain ESG criteria when evaluating an investment opportunity. The application of ESG criteria may result in the Fund (i) having exposure to certain securities or industry sectors that are significantly different than the composition of the Fund's benchmark; and (ii) performing differently than other funds and strategies in its peer group that do not take into account ESG criteria or the Fund's benchmark.


Yield Risk: There can be no guarantee that the Fund will achieve or maintain any particular level of yield.


Debt Securities Risk: The risks of investing in debt or fixed-income securities include (without limitation): (i) credit risk, e.g., the issuer or guarantor of a debt security may be unable or unwilling (or be perceived as unable or unwilling) to make timely principal and/or interest payments or otherwise honor its obligations, or changes in an issuer’s credit rating or the market’s perception of an issuer’s creditworthiness may affect the value of the Fund’s investments; (ii) maturity risk, e.g., a debt security with a longer maturity may fluctuate in value more than one with a shorter maturity; (iii) market risk, e.g., low demand for debt securities may negatively impact their price; (iv) interest rate risk, e.g., when interest rates go up, the value of a debt security generally goes down, and when interest rates go down, the value of a debt security generally goes up (long-term debt securities are generally more susceptible to interest rate risk than short-term debt securities); and (v) call or prepayment risk, e.g., during a period of falling interest rates, the issuer may redeem a security by repaying it early, which may reduce the Fund’s income if the proceeds are reinvested at lower interest rates.


Interest rate risk is the risk that the value of the Fund’s investments in fixed income or debt securities will change because of changes in interest rates. There is a risk that interest rates across the financial system may change, possibly significantly and/or rapidly. Changes in interest rates or a lack of market participants may lead to decreased liquidity and increased volatility in the fixed-income or debt markets, making it more difficult for the Fund to sell its fixed-income or debt holdings. Decreased liquidity in the fixed-income or debt markets also may make it more difficult to value some or all of the Fund’s fixed-income or debt holdings. For most fixed-income investments, when market interest rates fall, prices of fixed-rate debt securities rise. However, when market interest rates fall, prices of certain variable and fixed-rate debt securities may be adversely affected (i.e., falling interest rates bring the possibility of prepayment risk, as an instrument may be redeemed before maturity).


Not all U.S. government debt securities are guaranteed by the U.S. government—some are backed only by the issuing agency, which must rely on its own resources to repay the debt. The Fund's yield will fluctuate with changes in short-term interest rates.


Foreign Securities Risk: Investments in foreign (non-U.S.) securities may be riskier than investments in U.S. securities. Foreign regulatory regimes and securities markets can have less stringent investor protections and disclosure standards and less liquid trading markets than U.S. regulatory regimes and securities markets, and can experience political, social and economic developments that may affect the value of the Fund's investments in foreign securities. Foreign securities may also subject the Fund's investments to changes in currency rates. Changes in the value of foreign currencies may make the return on an investment increase or decrease, unrelated to the quality or performance of the investment itself.


Emerging Markets Risk: The risks related to investing in foreign securities are generally greater with respect to securities of companies that conduct their business activities in emerging markets or whose securities are traded principally in emerging markets. The risks of investing in emerging markets include the risks of illiquidity, increased price volatility, smaller market capitalizations, less government regulation, less extensive and less frequent accounting, financial and other reporting requirements, loss resulting from problems in share registration and custody, substantial economic and political disruptions and the nationalization of foreign deposits or assets.


Sovereign Debt Risk: The debt securities issued by sovereign entities may decline as a result of default or other adverse credit event resulting from a sovereign debtor's unwillingness or inability to repay principal and pay interest in a timely manner, which may be affected by a variety of factors, including its cash flow situation, the extent of its reserves, the availability of sufficient foreign exchange on the date a payment is due, the relative size of the debt service burden to the economy as a whole, the sovereign debtor's policy toward international lenders, and the political constraints to which a sovereign debtor may be subject. Sovereign debt risk is increased for emerging market issuers.


High-Yield Securities Risk: Investments in high-yield securities or non-investment grade securities (commonly referred to as "junk bonds") are considered speculative because investments in such securities present a greater risk of loss than investments in higher quality securities. Such securities may, under certain circumstances, be less liquid than higher rated securities. These securities pay investors a premium (a high interest rate or yield) because of the potential illiquidity and increased risk of loss. These securities can also be subject to greater price volatility. In times of unusual or adverse market, economic or political conditions, these securities may experience higher than normal default rates.


Floating Rate Notes and Variable Rate Notes Risk: Floating and variable rate notes provide for a periodic adjustment in the interest rate paid on the securities. The rate adjustment intervals may be regular and range from daily up to annually, or may be based on an event, such as a change in the prime rate. Floating and variable rate notes may be subject to greater liquidity risk than other debt securities, meaning that there may be limitations on the Fund's ability to sell the securities at any given time. Securities with floating interest rates generally are less sensitive to interest rate changes, but may decline in value if their interest rates do not rise as much or as fast as interest rates in general. The terms of many floating rate notes and other instruments are tied to the London Interbank Offered Rate (“LIBOR”), which functions as a reference rate or benchmark. It is anticipated that LIBOR will be discontinued at the end of 2021, which may cause increased volatility and illiquidity in the markets for instruments with terms tied to LIBOR or other adverse consequences for these instruments. These events may adversely affect the Fund and its investments in such instruments.


Derivatives Risk: Derivatives are investments whose value depends on (or is derived from) the value of an underlying instrument, such as a security, asset, reference rate or index. Derivative strategies may expose the Fund to greater risk than if it had invested directly in the underlying instrument and often involve leverage, which may exaggerate a loss, potentially causing the Fund to lose more money than it originally invested and would have lost had it invested directly in the underlying instrument. For example, if the Fund is the seller of credit protection in a credit default swap, the Fund effectively adds leverage to its portfolio and is subject to the credit exposure on the full notional value of the swap. Derivatives may be difficult to sell, unwind or value. Derivatives may also be subject to counterparty risk, which is the risk that the counterparty (the party on the other side of the transaction) on a derivative transaction will be unable or unwilling to honor its contractual obligations to the Fund. Futures may be more volatile than direct investments in the instrument underlying the contract, and may not correlate perfectly to the underlying instrument. Futures and other derivatives also may involve a small initial investment relative to the risk assumed, which could result in losses greater than if they had not been used. Due to fluctuations in the price of the underlying asset, the Fund may not be able to profitably exercise an option and may lose its entire investment in an option. Forward commitments entail the risk that the instrument may be worth less when it is issued or received than the price the Fund agreed to pay when it made the commitment. The use of foreign currency forwards may result in currency exchange losses due to fluctuations in currency exchange rates or an imperfect correlation between portfolio holdings denominated in a particular currency and the forward contracts entered into by the Fund. Swaps may be subject to counterparty credit, correlation, valuation, liquidity and leveraging risks. Swap transactions tend to shift a Fund's investment exposure from one type of investment to another and may entail the risk that a party will default on its payment obligations to the Fund. Additionally, applicable regulators have adopted rules imposing certain margin requirements, including minimums on uncleared swaps, which may result in the Fund and its counterparties posting higher margin amounts for uncleared swaps. Certain standardized swaps are subject to mandatory central clearing and exchange trading. Central clearing, which interposes a central clearinghouse to each participant’s swap, and exchange trading are intended to reduce counterparty credit risk and increase liquidity but neither makes swap transactions risk-free. Derivatives may also increase the expenses of the Fund.


Liquidity and Valuation Risk: The Fund’s investments may be illiquid at the time of purchase or liquid at the time of purchase and subsequently become illiquid due to, among other things, events relating to the issuer of the securities, market events, operational issues, economic conditions, investor perceptions or lack of market participants. The lack of an active trading market may make it difficult to sell or obtain an accurate price for a security. If market conditions or issuer specific developments make it difficult to value securities, the Fund may value these securities using more subjective methods, such as fair value pricing. In such cases, the value determined for a security could be different than the value realized upon such security's sale. As a result, an investor could pay more than the market value when buying Fund shares or receive less than the market value when selling Fund shares. This could affect the proceeds of any redemption or the number of shares an investor receives upon purchase.


The Fund is subject to the risk that it could not meet redemption requests within the allowable time period without significant dilution of remaining investors' interests in the Fund. To meet redemption requests or to raise cash to pursue other investment opportunities, the Fund may be forced to sell securities at an unfavorable time and/or under unfavorable conditions, which may adversely affect the Fund.


Currency Risk: Changes in the value of foreign (non-U.S.) currencies relative to the U.S. dollar may adversely affect the Fund’s investments in foreign currencies or in securities that trade in, and receive revenues in, or in derivatives that provide exposure to, foreign currencies. These changes in value can make the return on an investment go up or down, entirely apart from the quality or performance of the investment itself. The Subadvisor may seek to reduce currency risk by hedging all or part of the exposure to various foreign currencies of the Fund’s assets by engaging in hedging transactions, including swaps, futures, forward currency contracts and other derivatives. The Subadvisor may from time to time attempt to hedge all or a portion of the perceived currency risk by engaging in similar hedging transactions. However, these transactions and techniques may not always work as intended, and in certain cases the Fund may be worse off than if it had not engaged in such hedging practices. In addition, certain market conditions may make it impossible or uneconomical to hedge against currency risk.


Money Market/Short-Term Securities Risk: To the extent the Fund holds cash or invests in money market or short-term securities, the Fund may be less likely to achieve its investment objective. In addition, it is possible that the Fund's investments in these instruments could lose money.
Risk Lose Money [Text] rr_RiskLoseMoney You can lose money by investing in the Fund.
RIsk Not Insured [Text] rr_RiskNotInsured 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 governmental agency.
Bar Chart and Performance Table [Heading] rr_BarChartAndPerformanceTableHeading Past Performance
Performance Narrative [Text Block] rr_PerformanceNarrativeTextBlock

The following bar chart and table indicate some of the risks of investing in the Fund. The bar chart shows you how the Fund's calendar year performance has varied over time. Sales loads, if any, are not reflected in the bar chart. If they were, returns would be less than those shown. The average annual total returns table shows how the Fund's average annual total returns (before and after taxes) compare to those of a broad-based securities market index. The Fund has selected the JPMorgan EMBI Global Diversified Index as its primary benchmark. The JPMorgan EMBI Global Diversified Index is a market capitalization weighted, total return index tracking the traded market for U.S. dollar-denominated Brady Bonds, Eurobonds, traded loans and local market debt instruments issued by sovereign and quasi-sovereign entities.


Performance data for the classes varies based on differences in their fee and expense structures. Performance data is not shown for classes with less than one calendar year of performance. Past performance (before and after taxes) is not necessarily an indication of how the Fund will perform in the future. Please visit nylinvestments.com/funds for more recent performance information.


Effective February 28, 2017, the Fund's principal investment strategies changed. Effective June 21, 2019, the Fund's subadvisor, investment objective and principal investment strategies changed. The performance in the bar chart and table prior to those dates reflects the Fund’s prior subadvisor, investment objective and principal investment strategies.

Performance Information Illustrates Variability of Returns [Text] rr_PerformanceInformationIllustratesVariabilityOfReturns The following bar chart and table indicate some of the risks of investing in the Fund.
Performance One Year or Less [Text] rr_PerformanceOneYearOrLess Performance data is not shown for classes with less than one calendar year of performance.
Performance Availability Website Address [Text] rr_PerformanceAvailabilityWebSiteAddress nylinvestments.com/funds
Performance Past Does Not Indicate Future [Text] rr_PerformancePastDoesNotIndicateFuture Past performance (before and after taxes) is not necessarily an indication of how the Fund will perform in the future.
Bar Chart [Heading] rr_BarChartHeading Annual Returns, Class I Shares* (by calendar year 2010-2019)
Bar Chart Does Not Reflect Sales Loads [Text] rr_BarChartDoesNotReflectSalesLoads Sales loads, if any, are not reflected in the bar chart. If they were, returns would be less than those shown.
Bar Chart Footnotes [Text Block] rr_BarChartFootnotesTextBlock

*Previously, the bar chart presented the Fund's annual returns for Class B shares. Class I shares are presented for consistency across the MainStay Fund complex.

Bar Chart Closing [Text Block] rr_BarChartClosingTextBlock
   

Best Quarter

 

3Q/10

9.51

%

Worst Quarter

 

2Q/13

-6.83

%
Bar Chart, Reason Selected Class Different from Immediately Preceding Period [Text] rr_BarChartReasonSelectedClassDifferentFromImmediatelyPrecedingPeriod Previously, the bar chart presented the Fund's annual returns for Class B shares. Class I shares are presented for consistency across the MainStay Fund complex.
Highest Quarterly Return, Label rr_HighestQuarterlyReturnLabel Best Quarter
Highest Quarterly Return, Date rr_BarChartHighestQuarterlyReturnDate Sep. 30, 2010
Highest Quarterly Return rr_BarChartHighestQuarterlyReturn 9.51%
Lowest Quarterly Return, Label rr_LowestQuarterlyReturnLabel Worst Quarter
Lowest Quarterly Return, Date rr_BarChartLowestQuarterlyReturnDate Jun. 30, 2013
Lowest Quarterly Return rr_BarChartLowestQuarterlyReturn (6.83%)
Performance Table Heading rr_PerformanceTableHeading Average Annual Total Returns (for the periods ended December 31, 2019)
Index No Deduction for Fees, Expenses, Taxes [Text] rr_IndexNoDeductionForFeesExpensesTaxes (reflects no deductions for fees, expenses, or taxes)
Performance Table Uses Highest Federal Rate rr_PerformanceTableUsesHighestFederalRate After-tax returns are calculated using the highest individual federal marginal income tax rates in effect at the time of each distribution or capital gain or upon the sale of fund shares, 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 tax situation and may differ from those shown. After-tax returns are not relevant if you hold your shares through tax-deferred arrangements, such as 401(k) plans or individual retirement accounts.
Performance Table One Class of after Tax Shown [Text] rr_PerformanceTableOneClassOfAfterTaxShown After-tax returns shown are for Class I shares. After-tax returns for the other share classes may vary.
Performance Table Explanation after Tax Higher rr_PerformanceTableExplanationAfterTaxHigher In some cases, the return after taxes may exceed the return before taxes due to an assumed tax benefit from any losses on a sale of shares at the end of the measurement period.
Performance Table Closing [Text Block] rr_PerformanceTableClosingTextBlock

After-tax returns are calculated using the highest individual federal marginal income tax rates in effect at the time of each distribution or capital gain or upon the sale of Fund shares, and do not reflect the impact of state and local taxes. In some cases, the return after taxes may exceed the return before taxes due to an assumed tax benefit from any losses on a sale of shares at the end of the measurement period. Actual after-tax returns depend on your tax situation and may differ from those shown. After-tax returns are not relevant if you hold your shares through tax-deferred arrangements, such as 401(k) plans or individual retirement accounts. After-tax returns shown are for Class I shares. After-tax returns for the other share classes may vary.
MainStay Candriam Emerging Markets Debt Fund | JPMorgan EMBI Global Diversified Index (reflects no deductions for fees, expenses, or taxes)  
Risk/Return: rr_RiskReturnAbstract  
1 Year rr_AverageAnnualReturnYear01 15.04%
5 Years rr_AverageAnnualReturnYear05 6.24%
10 Years rr_AverageAnnualReturnYear10 6.90%
MainStay Candriam Emerging Markets Debt Fund | Class A  
Risk/Return: rr_RiskReturnAbstract  
Maximum Sales Charge (Load) Imposed on Purchases (as a percentage of offering price) rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice 4.50%
Maximum Deferred Sales Charge (Load) (as a percentage of the lesser of the original offering price or redemption proceeds) rr_MaximumDeferredSalesChargeOverOther none [1]
Management Fees (as an annual percentage of the Fund's average daily net assets) rr_ManagementFeesOverAssets 0.70% [2]
Distribution and/or Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets 0.25%
Other Expenses rr_OtherExpensesOverAssets 0.31%
Acquired (Underlying) Fund Fees and Expenses rr_AcquiredFundFeesAndExpensesOverAssets 0.01%
Total Annual Fund Operating Expenses rr_ExpensesOverAssets 1.27%
Waivers / Reimbursements rr_FeeWaiverOrReimbursementOverAssets (0.09%) [3]
Total Annual Fund Operating Expenses After Waivers / Reimbursements rr_NetExpensesOverAssets 1.18% [3]
Expenses Deferred Charges [Text Block] rr_ExpensesDeferredChargesTextBlock No initial sales charge applies on investments of $1 million or more (and certain other qualified purchases). However, a contingent deferred sales charge of 1.00% may be imposed on certain redemptions made within 18 months of the date of purchase on shares that were purchased without an initial sales charge.
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 565
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 826
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 1,107
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 1,907
1 Year rr_AverageAnnualReturnYear01 10.28%
5 Years rr_AverageAnnualReturnYear05 5.08%
10 Years rr_AverageAnnualReturnYear10 5.34%
Inception Date rr_AverageAnnualReturnInceptionDate Jun. 01, 1998
MainStay Candriam Emerging Markets Debt Fund | INVESTOR CLASS  
Risk/Return: rr_RiskReturnAbstract  
Maximum Sales Charge (Load) Imposed on Purchases (as a percentage of offering price) rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice 4.50%
Maximum Deferred Sales Charge (Load) (as a percentage of the lesser of the original offering price or redemption proceeds) rr_MaximumDeferredSalesChargeOverOther none [1]
Management Fees (as an annual percentage of the Fund's average daily net assets) rr_ManagementFeesOverAssets 0.70% [2]
Distribution and/or Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets 0.25%
Other Expenses rr_OtherExpensesOverAssets 0.61%
Acquired (Underlying) Fund Fees and Expenses rr_AcquiredFundFeesAndExpensesOverAssets 0.01%
Total Annual Fund Operating Expenses rr_ExpensesOverAssets 1.57%
Waivers / Reimbursements rr_FeeWaiverOrReimbursementOverAssets (0.09%) [3]
Total Annual Fund Operating Expenses After Waivers / Reimbursements rr_NetExpensesOverAssets 1.48% [3]
Expenses Deferred Charges [Text Block] rr_ExpensesDeferredChargesTextBlock No initial sales charge applies on investments of $1 million or more (and certain other qualified purchases). However, a contingent deferred sales charge of 1.00% may be imposed on certain redemptions made within 18 months of the date of purchase on shares that were purchased without an initial sales charge.
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 594
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 915
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 1,259
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 2,226
1 Year rr_AverageAnnualReturnYear01 9.91%
5 Years rr_AverageAnnualReturnYear05 4.84%
10 Years rr_AverageAnnualReturnYear10 5.15%
Inception Date rr_AverageAnnualReturnInceptionDate Feb. 28, 2008
MainStay Candriam Emerging Markets Debt Fund | Class B  
Risk/Return: rr_RiskReturnAbstract  
Maximum Sales Charge (Load) Imposed on Purchases (as a percentage of offering price) rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice none [4]
Maximum Deferred Sales Charge (Load) (as a percentage of the lesser of the original offering price or redemption proceeds) rr_MaximumDeferredSalesChargeOverOther 5.00% [4]
Management Fees (as an annual percentage of the Fund's average daily net assets) rr_ManagementFeesOverAssets 0.70% [2],[4]
Distribution and/or Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets 1.00% [4]
Other Expenses rr_OtherExpensesOverAssets 0.61% [4]
Acquired (Underlying) Fund Fees and Expenses rr_AcquiredFundFeesAndExpensesOverAssets 0.01% [4]
Total Annual Fund Operating Expenses rr_ExpensesOverAssets 2.32% [4]
Waivers / Reimbursements rr_FeeWaiverOrReimbursementOverAssets (0.09%) [3],[4]
Total Annual Fund Operating Expenses After Waivers / Reimbursements rr_NetExpensesOverAssets 2.23% [3],[4]
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 726
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 1,016
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 1,432
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 2,461
Expense Example, No Redemption, 1 Year rr_ExpenseExampleNoRedemptionYear01 226
Expense Example, No Redemption, 3 Years rr_ExpenseExampleNoRedemptionYear03 716
Expense Example, No Redemption, 5 Years rr_ExpenseExampleNoRedemptionYear05 1,232
Expense Example, No Redemption, 10 Years rr_ExpenseExampleNoRedemptionYear10 $ 2,461
1 Year rr_AverageAnnualReturnYear01 9.26%
5 Years rr_AverageAnnualReturnYear05 4.70%
10 Years rr_AverageAnnualReturnYear10 4.85%
Inception Date rr_AverageAnnualReturnInceptionDate Jun. 01, 1998
MainStay Candriam Emerging Markets Debt Fund | Class C  
Risk/Return: rr_RiskReturnAbstract  
Maximum Sales Charge (Load) Imposed on Purchases (as a percentage of offering price) rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice none
Maximum Deferred Sales Charge (Load) (as a percentage of the lesser of the original offering price or redemption proceeds) rr_MaximumDeferredSalesChargeOverOther 1.00%
Management Fees (as an annual percentage of the Fund's average daily net assets) rr_ManagementFeesOverAssets 0.70% [2]
Distribution and/or Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets 1.00%
Other Expenses rr_OtherExpensesOverAssets 0.61%
Acquired (Underlying) Fund Fees and Expenses rr_AcquiredFundFeesAndExpensesOverAssets 0.01%
Total Annual Fund Operating Expenses rr_ExpensesOverAssets 2.32%
Waivers / Reimbursements rr_FeeWaiverOrReimbursementOverAssets (0.09%) [3]
Total Annual Fund Operating Expenses After Waivers / Reimbursements rr_NetExpensesOverAssets 2.23% [3]
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 326
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 716
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 1,232
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 2,649
Expense Example, No Redemption, 1 Year rr_ExpenseExampleNoRedemptionYear01 226
Expense Example, No Redemption, 3 Years rr_ExpenseExampleNoRedemptionYear03 716
Expense Example, No Redemption, 5 Years rr_ExpenseExampleNoRedemptionYear05 1,232
Expense Example, No Redemption, 10 Years rr_ExpenseExampleNoRedemptionYear10 $ 2,649
1 Year rr_AverageAnnualReturnYear01 13.25%
5 Years rr_AverageAnnualReturnYear05 5.01%
10 Years rr_AverageAnnualReturnYear10 4.84%
Inception Date rr_AverageAnnualReturnInceptionDate Sep. 01, 1998
MainStay Candriam Emerging Markets Debt Fund | Class I  
Risk/Return: rr_RiskReturnAbstract  
Maximum Sales Charge (Load) Imposed on Purchases (as a percentage of offering price) rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice none
Maximum Deferred Sales Charge (Load) (as a percentage of the lesser of the original offering price or redemption proceeds) rr_MaximumDeferredSalesChargeOverOther none
Management Fees (as an annual percentage of the Fund's average daily net assets) rr_ManagementFeesOverAssets 0.70% [2]
Distribution and/or Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets none
Other Expenses rr_OtherExpensesOverAssets 0.31%
Acquired (Underlying) Fund Fees and Expenses rr_AcquiredFundFeesAndExpensesOverAssets 0.01%
Total Annual Fund Operating Expenses rr_ExpensesOverAssets 1.02%
Waivers / Reimbursements rr_FeeWaiverOrReimbursementOverAssets (0.16%) [3]
Total Annual Fund Operating Expenses After Waivers / Reimbursements rr_NetExpensesOverAssets 0.86% [3]
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 88
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 309
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 548
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 1,233
Annual Return 2010 rr_AnnualReturn2010 14.14%
Annual Return 2011 rr_AnnualReturn2011 4.37%
Annual Return 2012 rr_AnnualReturn2012 19.49%
Annual Return 2013 rr_AnnualReturn2013 (5.44%)
Annual Return 2014 rr_AnnualReturn2014 (1.27%)
Annual Return 2015 rr_AnnualReturn2015 (2.02%)
Annual Return 2016 rr_AnnualReturn2016 14.92%
Annual Return 2017 rr_AnnualReturn2017 11.59%
Annual Return 2018 rr_AnnualReturn2018 (6.54%)
Annual Return 2019 rr_AnnualReturn2019 15.68%
1 Year rr_AverageAnnualReturnYear01 15.68%
5 Years rr_AverageAnnualReturnYear05 6.32%
10 Years rr_AverageAnnualReturnYear10 6.09%
Inception Date rr_AverageAnnualReturnInceptionDate Aug. 31, 2007
MainStay Candriam Emerging Markets Debt Fund | Class I | After Taxes on Distributions  
Risk/Return: rr_RiskReturnAbstract  
1 Year rr_AverageAnnualReturnYear01 13.53%
5 Years rr_AverageAnnualReturnYear05 4.38%
10 Years rr_AverageAnnualReturnYear10 3.70%
MainStay Candriam Emerging Markets Debt Fund | Class I | After Taxes on Distributions and Sale of Fund Shares  
Risk/Return: rr_RiskReturnAbstract  
1 Year rr_AverageAnnualReturnYear01 9.23%
5 Years rr_AverageAnnualReturnYear05 3.97%
10 Years rr_AverageAnnualReturnYear10 3.72%
MainStay Candriam Emerging Markets Debt Fund | Class R6  
Risk/Return: rr_RiskReturnAbstract  
Maximum Sales Charge (Load) Imposed on Purchases (as a percentage of offering price) rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice none
Maximum Deferred Sales Charge (Load) (as a percentage of the lesser of the original offering price or redemption proceeds) rr_MaximumDeferredSalesChargeOverOther none
Management Fees (as an annual percentage of the Fund's average daily net assets) rr_ManagementFeesOverAssets 0.70% [2]
Distribution and/or Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets none
Other Expenses rr_OtherExpensesOverAssets 0.20%
Acquired (Underlying) Fund Fees and Expenses rr_AcquiredFundFeesAndExpensesOverAssets 0.01%
Total Annual Fund Operating Expenses rr_ExpensesOverAssets 0.91%
Waivers / Reimbursements rr_FeeWaiverOrReimbursementOverAssets (0.05%) [3]
Total Annual Fund Operating Expenses After Waivers / Reimbursements rr_NetExpensesOverAssets 0.86% [3]
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 88
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 285
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 499
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 1,115
[1] No initial sales charge applies on investments of $1 million or more (and certain other qualified purchases). However, a contingent deferred sales charge of 1.00% may be imposed on certain redemptions made within 18 months of the date of purchase on shares that were purchased without an initial sales charge.
[2] Restated to reflect the elimination of the Fund's fund accounting service fee. The management fee is as follows: 0.70% on assets up to $500 million and 0.65% on assets over $500 million.
[3] New York Life Investment Management LLC ("New York Life Investments") has contractually agreed to waive fees and/or reimburse expenses so that Total Annual Fund Operating Expenses (excluding taxes, interest, litigation, extraordinary expenses, brokerage and other transaction expenses relating to the purchase or sale of portfolio investments, and acquired (underlying) fund fees and expenses) do not exceed the following percentages of its average daily net assets: Class A, 1.17%; and Class I, 0.85%. New York Life Investments will apply an equivalent waiver or reimbursement, in an equal number of basis points as the Class A shares waiver/reimbursement, to Investor Class, Class B and Class C shares. In addition, New York Life Investments will waive fees and/or reimburse expenses so that Total Annual Fund Operating Expenses (excluding taxes, interest, litigation, extraordinary expenses, brokerage and other transaction expenses relating to the purchase or sale of portfolio investments, and acquired (underlying) fund fees and expenses) of Class R6 do not exceed those of Class I. This agreement will remain in effect until February 28, 2021, and shall renew automatically for one-year terms unless New York Life Investments provides written notice of termination prior to the start of the next term or upon approval of the Board of Trustees of the Fund.
[4] Class B shares are closed to all new purchases as well as additional investments by existing Class B shareholders.