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MainStay Epoch U.S. Equity Yield Fund  
Risk/Return: rr_RiskReturnAbstract  
Risk/Return [Heading] rr_RiskReturnHeading MainStay Epoch U.S. Equity Yield Fund
Objective [Heading] rr_ObjectiveHeading Investment Objective
Objective, Primary [Text Block] rr_ObjectivePrimaryTextBlock

The Fund seeks current income and capital appreciation.
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 101 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 18% of the average value of its portfolio.

Portfolio Turnover, Rate rr_PortfolioTurnoverRate 18.00%
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
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

The Fund generally invests in a diversified portfolio consisting of equity securities of U.S. companies that have a history of attractive dividend yields and positive growth in operating cash flow. Under normal circumstances, the Fund invests at least 80% of its assets (net assets plus any borrowings for investment purposes) in equity securities of dividend-paying U.S. companies across all market capitalizations. Generally, U.S. companies are companies organized in the U.S. that trade primarily in U.S. securities markets. The Fund may invest up to 15% of its net assets in foreign securities. Generally, foreign securities are issued by companies organized outside the U.S. or that trade primarily in non-U.S. securities markets.


Investment Process: Epoch Investment Partners, Inc., the Fund's Subadvisor, invests primarily in companies that generate increasing levels of free cash flow and have management teams that the Subadvisor believes allocate free cash flow effectively to create shareholder value.


The security selection process focuses on free-cash-flow analytics as opposed to traditional accounting-based metrics. The Subadvisor seeks to identify companies with a consistent, straightforward ability to both generate free cash flow and to intelligently allocate it among internal reinvestment opportunities, acquisitions, dividends, share repurchases and/or debt reduction.


The Subadvisor seeks to find and invest in companies that meet its definition of quality-companies that are free cash flow positive or becoming free cash flow positive, that are debt free or deleveraging, and that are led by strong management. The Subadvisor evaluates whether a company has a focus on shareholder yield by analyzing the company's existing cash dividend, the company's share repurchase activities, and the company's debt reduction activities as well as the likelihood of positive changes to each of these criteria, among other factors.


The Subadvisor may sell or reduce a position in a security when it believes its investment objectives have been met or if the investment thesis is failing to materialize. The Subadvisor may also sell or reduce a position in a security if it sees an interruption to the dividend policy, a deterioration in fundamentals or when the security is deemed less attractive relative to another security on a return/risk basis.

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.


Equity Securities Risk: Investments in common stocks and other equity securities are particularly subject to the risk of changing economic, stock market, industry and company conditions and the risks inherent in the portfolio managers' ability to anticipate such changes that can adversely affect the value of the Fund's holdings.


Dividend-Paying Stock Risk: The Fund’s emphasis on equity and equity-related securities that produce income or other distributions subjects the Fund to the risk that such securities may fall out of favor with investors and underperform the market. Depending upon market conditions, income producing stocks that meet the Fund’s investment criteria may not be widely available and/or may be highly concentrated in only a few market sectors. This may limit the ability of the Fund to produce current income while remaining fully diversified. Also, an issuer may reduce or eliminate its income payments or other distributions, particularly during a market downturn. The distributions received by the Fund may not qualify as income for Fund investors.


Value Stock Risk: Value stocks may never reach what the Subadvisor believes is their full value or they may go down in value. In addition, different types of stocks tend to shift in and out of favor depending on market and economic conditions, and therefore the Fund's performance may be lower or higher than that of funds that invest in other types of equity securities.


Market Capitalization Risk: To the extent the Fund invests in securities issued by small-, mid-, or large-cap companies, the Fund will be subject to the risks associated with securities issued by companies of the applicable market capitalization.  Securities of small-cap and mid-cap companies may be subject to greater price volatility, significantly lower trading volumes, cyclical, static or moderate growth prospects and greater spreads between their bid and ask prices than securities of larger companies. Smaller capitalization companies frequently rely on narrower product lines and niche markets and may be more vulnerable to adverse business or market developments.  Securities issued by larger companies may have less growth potential and may not be able to attain the high growth rates of successful smaller companies, especially during strong economic periods.  In addition, larger companies may be less capable of responding quickly to competitive challenges and industry changes, including those resulting from improvements in technology, and may suffer sharper price declines as a result of earnings disappointments.  There is a risk that the securities issued by companies of a certain market capitalization may underperform the broader market at any given time.


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. These risks may be greater with respect to securities of companies that conduct their business activities in emerging markets or whose securities are traded principally in emerging markets.
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, as well as a composite index. The Fund has selected the Russell 1000® Value Index as its primary benchmark. The Russell 1000® Value Index measures the performance of the large-cap value segment of the U.S. equity universe. It includes those Russell 1000® Index companies with lower price-to-book ratios and lower expected growth values. The Fund has selected the U.S. Equity Yield Composite Index as its secondary benchmark. The U.S. Equity Yield Composite Index consists of the MSCI USA High Dividend Yield Index and the MSCI USA Minimum Volatility (USD) Index weighted at 60% and 40%, respectively. The MSCI USA High Dividend Yield Index is based on the MSCI USA Index and includes large- and mid-cap stocks. The MSCI USA High Dividend Yield Index is designed to reflect the performance of equities in the MSCI USA Index (excluding real estate investment trusts) with higher dividend income and quality characteristics than average dividend yields that are both sustainable and persistent. The MSCI USA Minimum Volatility (USD) Index aims to reflect the performance characteristics of a minimum variance strategy applied to the large- and mid-cap USA equity universe. The MSCI USA Minimum Volatility (USD) Index is calculated by optimizing the MSCI USA Index in USD for the lowest absolute risk (within a given set of constraints).


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.


On September 17, 2012, the Fund changed its investment objective and principal investment strategies. Performance figures for dates prior to September 17, 2012 reflect the Fund's prior 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 Additional Market Index [Text] rr_PerformanceAdditionalMarketIndex The Fund has selected the U.S. Equity Yield Composite Index as its secondary benchmark. The U.S. Equity Yield Composite Index consists of the MSCI USA High Dividend Yield Index and the MSCI USA Minimum Volatility (USD) Index weighted at 60% and 40%, respectively. The MSCI USA High Dividend Yield Index is based on the MSCI USA Index and includes large- and mid-cap stocks. The MSCI USA High Dividend Yield Index is designed to reflect the performance of equities in the MSCI USA Index (excluding real estate investment trusts) with higher dividend income and quality characteristics than average dividend yields that are both sustainable and persistent. The MSCI USA Minimum Volatility (USD) Index aims to reflect the performance characteristics of a minimum variance strategy applied to the large- and mid-cap USA equity universe. The MSCI USA Minimum Volatility (USD) Index is calculated by optimizing the MSCI USA Index in USD for the lowest absolute risk (within a given set of constraints).
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 Closing [Text Block] rr_BarChartClosingTextBlock
   

Best Quarter

 

1Q/13

12.82

%

Worst Quarter

 

3Q/11

-16.22

%
Highest Quarterly Return, Label rr_HighestQuarterlyReturnLabel Best Quarter
Highest Quarterly Return, Date rr_BarChartHighestQuarterlyReturnDate Mar. 31, 2013
Highest Quarterly Return rr_BarChartHighestQuarterlyReturn 12.82%
Lowest Quarterly Return, Label rr_LowestQuarterlyReturnLabel Worst Quarter
Lowest Quarterly Return, Date rr_BarChartLowestQuarterlyReturnDate Sep. 30, 2011
Lowest Quarterly Return rr_BarChartLowestQuarterlyReturn (16.22%)
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 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 Epoch U.S. Equity Yield Fund | Russell 1000® Value Index (reflects no deductions for fees, expenses, or taxes)  
Risk/Return: rr_RiskReturnAbstract  
1 Year rr_AverageAnnualReturnYear01 26.54%
5 Years or Since Inception rr_AverageAnnualReturnYear05 8.29%
10 Years rr_AverageAnnualReturnYear10 11.80%
MainStay Epoch U.S. Equity Yield Fund | U.S. Equity Yield Composite Index (reflects no deductions for fees, expenses, or taxes)  
Risk/Return: rr_RiskReturnAbstract  
1 Year rr_AverageAnnualReturnYear01 23.63%
5 Years or Since Inception rr_AverageAnnualReturnYear05 10.63%
10 Years rr_AverageAnnualReturnYear10 12.99%
MainStay Epoch U.S. Equity Yield Fund | Class A  
Risk/Return: rr_RiskReturnAbstract  
Maximum Sales Charge (Load) Imposed on Purchases (as a percentage of offering price) rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice 5.50%
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 0.69% [2]
Distribution and/or Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets 0.25%
Other Expenses rr_OtherExpensesOverAssets 0.14%
Total Annual Fund Operating Expenses rr_ExpensesOverAssets 1.08%
Waivers / Reimbursements rr_FeeWaiverOrReimbursementOverAssets none [3]
Total Annual Fund Operating Expenses After Waivers / Reimbursements rr_NetExpensesOverAssets 1.08% [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 $ 654
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 875
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 1,113
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 1,795
1 Year rr_AverageAnnualReturnYear01 16.89%
5 Years or Since Inception rr_AverageAnnualReturnYear05 7.44%
10 Years rr_AverageAnnualReturnYear10 10.37%
Inception Date rr_AverageAnnualReturnInceptionDate Feb. 03, 2009
MainStay Epoch U.S. Equity Yield Fund | Investor Class  
Risk/Return: rr_RiskReturnAbstract  
Maximum Sales Charge (Load) Imposed on Purchases (as a percentage of offering price) rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice 5.50%
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 0.69% [2]
Distribution and/or Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets 0.25%
Other Expenses rr_OtherExpensesOverAssets 0.41%
Total Annual Fund Operating Expenses rr_ExpensesOverAssets 1.35%
Waivers / Reimbursements rr_FeeWaiverOrReimbursementOverAssets (0.01%) [3]
Total Annual Fund Operating Expenses After Waivers / Reimbursements rr_NetExpensesOverAssets 1.34% [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 $ 679
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 953
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 1,248
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 2,084
1 Year rr_AverageAnnualReturnYear01 16.68%
5 Years or Since Inception rr_AverageAnnualReturnYear05 7.25%
10 Years rr_AverageAnnualReturnYear10 10.22%
Inception Date rr_AverageAnnualReturnInceptionDate Nov. 16, 2009
MainStay Epoch U.S. Equity Yield 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 0.69% [2],[4]
Distribution and/or Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets 1.00% [4]
Other Expenses rr_OtherExpensesOverAssets 0.41% [4]
Total Annual Fund Operating Expenses rr_ExpensesOverAssets 2.10% [4]
Waivers / Reimbursements rr_FeeWaiverOrReimbursementOverAssets (0.01%) [3],[4]
Total Annual Fund Operating Expenses After Waivers / Reimbursements rr_NetExpensesOverAssets 2.09% [3],[4]
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 712
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 957
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 1,328
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 2,239
Expense Example, No Redemption, 1 Year rr_ExpenseExampleNoRedemptionYear01 212
Expense Example, No Redemption, 3 Years rr_ExpenseExampleNoRedemptionYear03 657
Expense Example, No Redemption, 5 Years rr_ExpenseExampleNoRedemptionYear05 1,128
Expense Example, No Redemption, 10 Years rr_ExpenseExampleNoRedemptionYear10 $ 2,239
1 Year rr_AverageAnnualReturnYear01 17.52%
5 Years or Since Inception rr_AverageAnnualReturnYear05 7.98%
Inception Date rr_AverageAnnualReturnInceptionDate Feb. 28, 2017
MainStay Epoch U.S. Equity Yield 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 0.69% [2]
Distribution and/or Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets 1.00%
Other Expenses rr_OtherExpensesOverAssets 0.41%
Total Annual Fund Operating Expenses rr_ExpensesOverAssets 2.10%
Waivers / Reimbursements rr_FeeWaiverOrReimbursementOverAssets (0.01%) [3]
Total Annual Fund Operating Expenses After Waivers / Reimbursements rr_NetExpensesOverAssets 2.09% [3]
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 312
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 657
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 1,128
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 2,430
Expense Example, No Redemption, 1 Year rr_ExpenseExampleNoRedemptionYear01 212
Expense Example, No Redemption, 3 Years rr_ExpenseExampleNoRedemptionYear03 657
Expense Example, No Redemption, 5 Years rr_ExpenseExampleNoRedemptionYear05 1,128
Expense Example, No Redemption, 10 Years rr_ExpenseExampleNoRedemptionYear10 $ 2,430
1 Year rr_AverageAnnualReturnYear01 21.45%
5 Years or Since Inception rr_AverageAnnualReturnYear05 7.65%
10 Years rr_AverageAnnualReturnYear10 10.02%
Inception Date rr_AverageAnnualReturnInceptionDate Nov. 16, 2009
MainStay Epoch U.S. Equity Yield 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 0.69% [2]
Distribution and/or Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets none
Other Expenses rr_OtherExpensesOverAssets 0.14%
Total Annual Fund Operating Expenses rr_ExpensesOverAssets 0.83%
Waivers / Reimbursements rr_FeeWaiverOrReimbursementOverAssets (0.10%) [3]
Total Annual Fund Operating Expenses After Waivers / Reimbursements rr_NetExpensesOverAssets 0.73% [3]
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 75
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 255
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 451
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 1,016
Annual Return 2010 rr_AnnualReturn2010 12.46%
Annual Return 2011 rr_AnnualReturn2011 0.23%
Annual Return 2012 rr_AnnualReturn2012 12.52%
Annual Return 2013 rr_AnnualReturn2013 30.19%
Annual Return 2014 rr_AnnualReturn2014 14.85%
Annual Return 2015 rr_AnnualReturn2015 (2.49%)
Annual Return 2016 rr_AnnualReturn2016 14.66%
Annual Return 2017 rr_AnnualReturn2017 16.91%
Annual Return 2018 rr_AnnualReturn2018 (5.37%)
Annual Return 2019 rr_AnnualReturn2019 23.97%
1 Year rr_AverageAnnualReturnYear01 23.97%
5 Years or Since Inception rr_AverageAnnualReturnYear05 8.92%
10 Years rr_AverageAnnualReturnYear10 11.26%
Inception Date rr_AverageAnnualReturnInceptionDate Dec. 03, 2008
MainStay Epoch U.S. Equity Yield Fund | Class I | After Taxes on Distributions  
Risk/Return: rr_RiskReturnAbstract  
1 Year rr_AverageAnnualReturnYear01 22.77%
5 Years or Since Inception rr_AverageAnnualReturnYear05 7.64%
10 Years rr_AverageAnnualReturnYear10 9.66%
MainStay Epoch U.S. Equity Yield Fund | Class I | After Taxes on Distributions and Sale of Fund Shares  
Risk/Return: rr_RiskReturnAbstract  
1 Year rr_AverageAnnualReturnYear01 14.98%
5 Years or Since Inception rr_AverageAnnualReturnYear05 6.78%
10 Years rr_AverageAnnualReturnYear10 8.96%
MainStay Epoch U.S. Equity Yield Fund | Class R1  
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 0.69% [2]
Distribution and/or Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets none
Other Expenses rr_OtherExpensesOverAssets 0.24%
Total Annual Fund Operating Expenses rr_ExpensesOverAssets 0.93%
Waivers / Reimbursements rr_FeeWaiverOrReimbursementOverAssets none [3]
Total Annual Fund Operating Expenses After Waivers / Reimbursements rr_NetExpensesOverAssets 0.93% [3]
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 95
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 296
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 515
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 1,143
1 Year rr_AverageAnnualReturnYear01 23.85%
5 Years or Since Inception rr_AverageAnnualReturnYear05 10.15%
Inception Date rr_AverageAnnualReturnInceptionDate Feb. 28, 2017
MainStay Epoch U.S. Equity Yield Fund | Class R2  
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 0.69% [2]
Distribution and/or Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets 0.25%
Other Expenses rr_OtherExpensesOverAssets 0.24%
Total Annual Fund Operating Expenses rr_ExpensesOverAssets 1.18%
Waivers / Reimbursements rr_FeeWaiverOrReimbursementOverAssets none [3]
Total Annual Fund Operating Expenses After Waivers / Reimbursements rr_NetExpensesOverAssets 1.18% [3]
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 120
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 375
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 649
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 1,432
1 Year rr_AverageAnnualReturnYear01 23.59%
5 Years or Since Inception rr_AverageAnnualReturnYear05 9.85%
Inception Date rr_AverageAnnualReturnInceptionDate Feb. 28, 2017
MainStay Epoch U.S. Equity Yield Fund | Class R3  
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 0.69% [2]
Distribution and/or Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets 0.50%
Other Expenses rr_OtherExpensesOverAssets 0.24%
Total Annual Fund Operating Expenses rr_ExpensesOverAssets 1.43%
Waivers / Reimbursements rr_FeeWaiverOrReimbursementOverAssets none [3]
Total Annual Fund Operating Expenses After Waivers / Reimbursements rr_NetExpensesOverAssets 1.43% [3]
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 146
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 452
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 782
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 1,713
1 Year rr_AverageAnnualReturnYear01 23.27%
5 Years or Since Inception rr_AverageAnnualReturnYear05 9.60%
Inception Date rr_AverageAnnualReturnInceptionDate Feb. 28, 2017
MainStay Epoch U.S. Equity Yield 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 0.69% [2]
Distribution and/or Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets none
Other Expenses rr_OtherExpensesOverAssets 0.05%
Total Annual Fund Operating Expenses rr_ExpensesOverAssets 0.74%
Waivers / Reimbursements rr_FeeWaiverOrReimbursementOverAssets (0.01%) [3]
Total Annual Fund Operating Expenses After Waivers / Reimbursements rr_NetExpensesOverAssets 0.73% [3]
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 75
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 236
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 410
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 917
1 Year rr_AverageAnnualReturnYear01 24.16%
5 Years or Since Inception rr_AverageAnnualReturnYear05 10.39%
Inception Date rr_AverageAnnualReturnInceptionDate Feb. 28, 2017
[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] The management fee is as follows: 0.70% on assets up to $500 million; 0.68% on assets from $500 million to $1 billion; 0.66% on assets from $1 billion to $2 billion; and 0.65% on assets over $2 billion.
[3] New York Life Investment Management LLC ("New York Life Investments") has contractually agreed to limit the transfer agency expenses charged to each of the Fund's share classes to a maximum of 0.35% of that share class's average daily net assets on an annual basis (excluding small account fees) after deducting any other applicable expense cap reimbursements or transfer agency waivers. 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) for Class I shares do not exceed 0.73%. 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. These agreements 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.