v3.25.2
Shareholder Report
 6 Months Ended
Apr. 30, 2025
USD ($)
Holding
Shareholder Report [Line Items]  
Document Type N-CSRS
Amendment Flag false
Registrant Name NEW YORK LIFE INVESTMENTS FUNDS
Entity Central Index Key 0000787441
Entity Investment Company Type N-1A
Document Period End Date Apr. 30, 2025
C000018685 [Member]  
Shareholder Report [Line Items]  
Fund Name NYLI MacKay Strategic Bond Fund
Class Name Class A
Trading Symbol MASAX
Annual or Semi-Annual Statement [Text Block] This semiannual shareholder report contains important information about NYLI MacKay Strategic Bond Fund (the "Fund") for the period November 1, 2024 to April 30, 2025.
Shareholder Report Annual or Semi-Annual semi-annual shareholder report
Additional Information [Text Block] You can find additional information about the Fund at dfinview.com/NYLIM. You can also request this information by contacting us at 800-624-6782.
Additional Information Phone Number 800-624-6782
Additional Information Website dfinview.com/NYLIM
Expenses [Text Block]
What were the Fund costs for the last six months?
(Based on a hypothetical $10,000 investment)
Share Class Name Costs of a $10,000 investment Costs paid as a percentage
of a $10,000 investment1
Class A $49 0.98%
1.
Annualized.
Expenses Paid, Amount $ 49
Expense Ratio, Percent 0.98% [1]
Performance Past Does Not Indicate Future [Text] Keep in mind that the Fund ’s past performance is not a good predictor of how the Fund will perform in the future.
Line Graph [Table Text Block]
Fund Performance
The following graph compares the initial and subsequent account values at the end of each of the most recently completed 10 semiannual reporting periods of the Fund (or for the life of the Fund, if shorter). It assumes a $15,000 initial investment at the beginning of the first fiscal period in an appropriate, broad-based securities market index and other additional indexes, if applicable, for the same period and reflects the deduction of all sales charges, where applicable.
Fund Performance - Growth of 10K
Average Annual Return [Table Text Block]
Average Annual Total Returns for the Period Ended April 30, 2025 Inception
Date		 Six
Months1		 One
Year		 Five
Years		 Ten
Years
Class A Shares - Including sales charges 2/28/1997 (1.55)% 4.59% 3.62% 2.44%
Class A Shares - Excluding sales charges 3.09% 9.52% 4.58% 2.91%
Bloomberg U.S. Aggregate Bond Index2 2.57% 8.02% (0.67)% 1.54%
Morningstar Multisector Bond Category Average3 2.25% 7.76% 4.19% 3.12%
1.
Not annualized.
2.
The Fund has selected the Bloomberg U.S. Aggregate Bond Index to represent a broad measure of market performance. The Bloomberg U.S. Aggregate Bond Index is a broad-based benchmark that measures the performance of the investment grade, U.S. dollar denominated, fixed-rate taxable bond market, including Treasuries, government-related and corporate securities, mortgage-backed securities (agency fixed-rate and hybrid adjustable rate mortgage pass-throughs), asset-backed securities and commercial mortgage-backed securities.
3.
The Morningstar Multisector Bond Category Average is representative of funds that seek income by diversifying their assets among several fixed-income sectors, usually U.S. government obligations, U.S. corporate bonds, foreign bonds, and high yield U.S. debt securities. These portfolios typically hold 35% to 65% of bond assets in securities that are not rated or are rated by a major agency such as Standard & Poor's or Moody's at the level of BB (considered speculative for taxable bonds) and below. Results are based on average total returns of similar funds with all dividends and capital gain distributions reinvested.
Performance Inception Date Feb. 28, 1997
No Deduction of Taxes [Text Block] The graph and table do not reflect the deduction of taxes that a shareholder would pay on Fund distributions or redemption of Fund shares.
Updated Performance Information Location [Text Block] Visit newyorklifeinvestments.com/funds for the most recent performance information.
Net Assets $ 995,196,754
Holdings Count | Holding 548
Investment Company Portfolio Turnover 85.00%
Additional Fund Statistics [Text Block]
Key Fund Statistics
Fund's net assets $995,196,754%
Total number of portfolio holdings 548%
Portfolio turnover rate 85%
Holdings [Text Block]
Graphical Representation of Holdings
The tables below show the investment makeup of the Fund; percentages indicated are based on the Fund's net assets.
Top Ten Holdings and/or Issuers*
U.S. Treasury Notes, 3.75%-4.625%, due 4/30/27-2/15/35 22.3%
Connecticut Avenue Securities Trust, 6.053%-14.204%, due 9/25/31-1/25/45 3.9%
FHLMC STACR REMIC Trust, 6.004%-11.454%, due 8/25/33-1/25/51 3.5%
GNMA, (zero coupon)-4.50%, due 7/20/44-2/16/66 3.1%
UMBS, 30 Year, 2.00%-5.50%, due 3/1/52-5/1/54 2.5%
Flagship Credit Auto Trust, 1.59%-6.30%, due 3/16/26-4/15/30 2.0%
FHLMC, (zero coupon)-9.304%, due 5/25/44-8/15/56 1.5%
Exeter Automobile Receivables Trust, 3.04%-10.45%, due 12/15/28-9/15/32 1.4%
Wells Fargo Commercial Mortgage Trust, 2.70%-5.122%, due 12/15/39-1/15/60 1.3%
CF Hippolyta Issuer LLC, 1.69%-2.60%, due 7/15/60-3/15/61 1.0%
* Excluding short-term investments
Portfolio Composition 
Corporate Bonds 28.8%
Mortgage-Backed Securities 26.9%
U.S. Government & Federal Agencies 25.3%
Asset-Backed Securities 11.8%
Foreign Government Bonds 4.1%
Loan Assignments 2.0%
Short-Term Investments 1.4%
Common Stocks 0.0%‡
Other Assets, Less Liabilities (0.3)%
‡
Less than one-tenth of a percent.
Largest Holdings [Text Block]
Top Ten Holdings and/or Issuers*
U.S. Treasury Notes, 3.75%-4.625%, due 4/30/27-2/15/35 22.3%
Connecticut Avenue Securities Trust, 6.053%-14.204%, due 9/25/31-1/25/45 3.9%
FHLMC STACR REMIC Trust, 6.004%-11.454%, due 8/25/33-1/25/51 3.5%
GNMA, (zero coupon)-4.50%, due 7/20/44-2/16/66 3.1%
UMBS, 30 Year, 2.00%-5.50%, due 3/1/52-5/1/54 2.5%
Flagship Credit Auto Trust, 1.59%-6.30%, due 3/16/26-4/15/30 2.0%
FHLMC, (zero coupon)-9.304%, due 5/25/44-8/15/56 1.5%
Exeter Automobile Receivables Trust, 3.04%-10.45%, due 12/15/28-9/15/32 1.4%
Wells Fargo Commercial Mortgage Trust, 2.70%-5.122%, due 12/15/39-1/15/60 1.3%
CF Hippolyta Issuer LLC, 1.69%-2.60%, due 7/15/60-3/15/61 1.0%
* Excluding short-term investments
C000018687 [Member]  
Shareholder Report [Line Items]  
Fund Name NYLI MacKay Strategic Bond Fund
Class Name Class C
Trading Symbol MSICX
Annual or Semi-Annual Statement [Text Block] This semiannual shareholder report contains important information about NYLI MacKay Strategic Bond Fund (the "Fund") for the period November 1, 2024 to April 30, 2025.
Shareholder Report Annual or Semi-Annual semi-annual shareholder report
Additional Information [Text Block] You can find additional information about the Fund at dfinview.com/NYLIM. You can also request this information by contacting us at 800-624-6782.
Additional Information Phone Number 800-624-6782
Additional Information Website dfinview.com/NYLIM
Expenses [Text Block]
What were the Fund costs for the last six months?
(Based on a hypothetical $10,000 investment)
Share Class Name Costs of a $10,000 investment Costs paid as a percentage
of a $10,000 investment1,2
Class C $99 1.97%
1.
Reflects fee waivers and/or expense reimbursements, without which expenses would have been higher.
2.
Annualized.
Expenses Paid, Amount $ 99
Expense Ratio, Percent 1.97% [2],[3]
Performance Past Does Not Indicate Future [Text] Keep in mind that the Fund ’s past performance is not a good predictor of how the Fund will perform in the future.
Line Graph [Table Text Block]
Fund Performance
The following graph compares the initial and subsequent account values at the end of each of the most recently completed 10 semiannual reporting periods of the Fund (or for the life of the Fund, if shorter). It assumes a $10,000 initial investment at the beginning of the first fiscal period in an appropriate, broad-based securities market index and other additional indexes, if applicable, for the same period and reflects the deduction of all sales charges, where applicable.
Fund Performance - Growth of 10K
Average Annual Return [Table Text Block]
Average Annual Total Returns for the Period Ended April 30, 2025 Inception
Date		 Six
Months1		 One
Year		 Five
Years		 Ten
Years
Class C Shares - Including sales charges 9/1/1998 1.60% 7.37% 3.61% 2.04%
Class C Shares - Excluding sales charges 2.60% 8.37% 3.61% 2.04%
Bloomberg U.S. Aggregate Bond Index2 2.57% 8.02% (0.67)% 1.54%
Morningstar Multisector Bond Category Average3 2.25% 7.76% 4.19% 3.12%
1.
Not annualized.
2.
The Fund has selected the Bloomberg U.S. Aggregate Bond Index to represent a broad measure of market performance. The Bloomberg U.S. Aggregate Bond Index is a broad-based benchmark that measures the performance of the investment grade, U.S. dollar denominated, fixed-rate taxable bond market, including Treasuries, government-related and corporate securities, mortgage-backed securities (agency fixed-rate and hybrid adjustable rate mortgage pass-throughs), asset-backed securities and commercial mortgage-backed securities.
3.
The Morningstar Multisector Bond Category Average is representative of funds that seek income by diversifying their assets among several fixed-income sectors, usually U.S. government obligations, U.S. corporate bonds, foreign bonds, and high yield U.S. debt securities. These portfolios typically hold 35% to 65% of bond assets in securities that are not rated or are rated by a major agency such as Standard & Poor's or Moody's at the level of BB (considered speculative for taxable bonds) and below. Results are based on average total returns of similar funds with all dividends and capital gain distributions reinvested.
Performance Inception Date Sep. 01, 1998
No Deduction of Taxes [Text Block] The graph and table do not reflect the deduction of taxes that a shareholder would pay on Fund distributions or redemption of Fund shares.
Updated Performance Information Location [Text Block] Visit newyorklifeinvestments.com/funds for the most recent performance information.
Net Assets $ 995,196,754
Holdings Count | Holding 548
Investment Company Portfolio Turnover 85.00%
Additional Fund Statistics [Text Block]
Key Fund Statistics
Fund's net assets $995,196,754%
Total number of portfolio holdings 548%
Portfolio turnover rate 85%
Holdings [Text Block]
Graphical Representation of Holdings
The tables below show the investment makeup of the Fund; percentages indicated are based on the Fund's net assets.
Top Ten Holdings and/or Issuers*
U.S. Treasury Notes, 3.75%-4.625%, due 4/30/27-2/15/35 22.3%
Connecticut Avenue Securities Trust, 6.053%-14.204%, due 9/25/31-1/25/45 3.9%
FHLMC STACR REMIC Trust, 6.004%-11.454%, due 8/25/33-1/25/51 3.5%
GNMA, (zero coupon)-4.50%, due 7/20/44-2/16/66 3.1%
UMBS, 30 Year, 2.00%-5.50%, due 3/1/52-5/1/54 2.5%
Flagship Credit Auto Trust, 1.59%-6.30%, due 3/16/26-4/15/30 2.0%
FHLMC, (zero coupon)-9.304%, due 5/25/44-8/15/56 1.5%
Exeter Automobile Receivables Trust, 3.04%-10.45%, due 12/15/28-9/15/32 1.4%
Wells Fargo Commercial Mortgage Trust, 2.70%-5.122%, due 12/15/39-1/15/60 1.3%
CF Hippolyta Issuer LLC, 1.69%-2.60%, due 7/15/60-3/15/61 1.0%
* Excluding short-term investments
Portfolio Composition 
Corporate Bonds 28.8%
Mortgage-Backed Securities 26.9%
U.S. Government & Federal Agencies 25.3%
Asset-Backed Securities 11.8%
Foreign Government Bonds 4.1%
Loan Assignments 2.0%
Short-Term Investments 1.4%
Common Stocks 0.0%‡
Other Assets, Less Liabilities (0.3)%
‡
Less than one-tenth of a percent.
Largest Holdings [Text Block]
Top Ten Holdings and/or Issuers*
U.S. Treasury Notes, 3.75%-4.625%, due 4/30/27-2/15/35 22.3%
Connecticut Avenue Securities Trust, 6.053%-14.204%, due 9/25/31-1/25/45 3.9%
FHLMC STACR REMIC Trust, 6.004%-11.454%, due 8/25/33-1/25/51 3.5%
GNMA, (zero coupon)-4.50%, due 7/20/44-2/16/66 3.1%
UMBS, 30 Year, 2.00%-5.50%, due 3/1/52-5/1/54 2.5%
Flagship Credit Auto Trust, 1.59%-6.30%, due 3/16/26-4/15/30 2.0%
FHLMC, (zero coupon)-9.304%, due 5/25/44-8/15/56 1.5%
Exeter Automobile Receivables Trust, 3.04%-10.45%, due 12/15/28-9/15/32 1.4%
Wells Fargo Commercial Mortgage Trust, 2.70%-5.122%, due 12/15/39-1/15/60 1.3%
CF Hippolyta Issuer LLC, 1.69%-2.60%, due 7/15/60-3/15/61 1.0%
* Excluding short-term investments
C000018688 [Member]  
Shareholder Report [Line Items]  
Fund Name NYLI MacKay Strategic Bond Fund
Class Name Class I
Trading Symbol MSDIX
Annual or Semi-Annual Statement [Text Block] This semiannual shareholder report contains important information about NYLI MacKay Strategic Bond Fund (the "Fund") for the period November 1, 2024 to April 30, 2025.
Shareholder Report Annual or Semi-Annual semi-annual shareholder report
Additional Information [Text Block] You can find additional information about the Fund at dfinview.com/NYLIM. You can also request this information by contacting us at 800-624-6782.
Additional Information Phone Number 800-624-6782
Additional Information Website dfinview.com/NYLIM
Expenses [Text Block]
What were the Fund costs for the last six months?
(Based on a hypothetical $10,000 investment)
Share Class Name Costs of a $10,000 investment Costs paid as a percentage
of a $10,000 investment1,2
Class I $35 0.70%
1.
Reflects fee waivers and/or expense reimbursements, without which expenses would have been higher.
2.
Annualized.
Expenses Paid, Amount $ 35
Expense Ratio, Percent 0.70% [4],[5]
Performance Past Does Not Indicate Future [Text] Keep in mind that the Fund ’s past performance is not a good predictor of how the Fund will perform in the future.
Line Graph [Table Text Block]
Fund Performance
The following graph compares the initial and subsequent account values at the end of each of the most recently completed 10 semiannual reporting periods of the Fund (or for the life of the Fund, if shorter). It assumes a $10,000 initial investment at the beginning of the first fiscal period in an appropriate, broad-based securities market index and other additional indexes, if applicable, for the same period and reflects the deduction of all sales charges, where applicable.
Fund Performance - Growth of 10K
Average Annual Return [Table Text Block]
Average Annual Total Returns for the Period Ended April 30, 2025 Inception
Date		 Six
Months1		 One
Year		 Five
Years		 Ten
Years
Class I Shares 1/2/2004 3.22% 9.82% 4.89% 3.19%
Bloomberg U.S. Aggregate Bond Index2 2.57% 8.02% (0.67)% 1.54%
Morningstar Multisector Bond Category Average3 2.25% 7.76% 4.19% 3.12%
1.
Not annualized.
2.
The Fund has selected the Bloomberg U.S. Aggregate Bond Index to represent a broad measure of market performance. The Bloomberg U.S. Aggregate Bond Index is a broad-based benchmark that measures the performance of the investment grade, U.S. dollar denominated, fixed-rate taxable bond market, including Treasuries, government-related and corporate securities, mortgage-backed securities (agency fixed-rate and hybrid adjustable rate mortgage pass-throughs), asset-backed securities and commercial mortgage-backed securities.
3.
The Morningstar Multisector Bond Category Average is representative of funds that seek income by diversifying their assets among several fixed-income sectors, usually U.S. government obligations, U.S. corporate bonds, foreign bonds, and high yield U.S. debt securities. These portfolios typically hold 35% to 65% of bond assets in securities that are not rated or are rated by a major agency such as Standard & Poor's or Moody's at the level of BB (considered speculative for taxable bonds) and below. Results are based on average total returns of similar funds with all dividends and capital gain distributions reinvested.
Performance Inception Date Jan. 02, 2004
No Deduction of Taxes [Text Block] The graph and table do not reflect the deduction of taxes that a shareholder would pay on Fund distributions or redemption of Fund shares.
Updated Performance Information Location [Text Block] Visit newyorklifeinvestments.com/funds for the most recent performance information.
Net Assets $ 995,196,754
Holdings Count | Holding 548
Investment Company Portfolio Turnover 85.00%
Additional Fund Statistics [Text Block]
Key Fund Statistics
Fund's net assets $995,196,754%
Total number of portfolio holdings 548%
Portfolio turnover rate 85%
Holdings [Text Block]
Graphical Representation of Holdings
The tables below show the investment makeup of the Fund; percentages indicated are based on the Fund's net assets.
Top Ten Holdings and/or Issuers*
U.S. Treasury Notes, 3.75%-4.625%, due 4/30/27-2/15/35 22.3%
Connecticut Avenue Securities Trust, 6.053%-14.204%, due 9/25/31-1/25/45 3.9%
FHLMC STACR REMIC Trust, 6.004%-11.454%, due 8/25/33-1/25/51 3.5%
GNMA, (zero coupon)-4.50%, due 7/20/44-2/16/66 3.1%
UMBS, 30 Year, 2.00%-5.50%, due 3/1/52-5/1/54 2.5%
Flagship Credit Auto Trust, 1.59%-6.30%, due 3/16/26-4/15/30 2.0%
FHLMC, (zero coupon)-9.304%, due 5/25/44-8/15/56 1.5%
Exeter Automobile Receivables Trust, 3.04%-10.45%, due 12/15/28-9/15/32 1.4%
Wells Fargo Commercial Mortgage Trust, 2.70%-5.122%, due 12/15/39-1/15/60 1.3%
CF Hippolyta Issuer LLC, 1.69%-2.60%, due 7/15/60-3/15/61 1.0%
* Excluding short-term investments
Portfolio Composition 
Corporate Bonds 28.8%
Mortgage-Backed Securities 26.9%
U.S. Government & Federal Agencies 25.3%
Asset-Backed Securities 11.8%
Foreign Government Bonds 4.1%
Loan Assignments 2.0%
Short-Term Investments 1.4%
Common Stocks 0.0%‡
Other Assets, Less Liabilities (0.3)%
‡
Less than one-tenth of a percent.
Largest Holdings [Text Block]
Top Ten Holdings and/or Issuers*
U.S. Treasury Notes, 3.75%-4.625%, due 4/30/27-2/15/35 22.3%
Connecticut Avenue Securities Trust, 6.053%-14.204%, due 9/25/31-1/25/45 3.9%
FHLMC STACR REMIC Trust, 6.004%-11.454%, due 8/25/33-1/25/51 3.5%
GNMA, (zero coupon)-4.50%, due 7/20/44-2/16/66 3.1%
UMBS, 30 Year, 2.00%-5.50%, due 3/1/52-5/1/54 2.5%
Flagship Credit Auto Trust, 1.59%-6.30%, due 3/16/26-4/15/30 2.0%
FHLMC, (zero coupon)-9.304%, due 5/25/44-8/15/56 1.5%
Exeter Automobile Receivables Trust, 3.04%-10.45%, due 12/15/28-9/15/32 1.4%
Wells Fargo Commercial Mortgage Trust, 2.70%-5.122%, due 12/15/39-1/15/60 1.3%
CF Hippolyta Issuer LLC, 1.69%-2.60%, due 7/15/60-3/15/61 1.0%
* Excluding short-term investments
C000185554 [Member]  
Shareholder Report [Line Items]  
Fund Name NYLI MacKay Strategic Bond Fund
Class Name Class R6
Trading Symbol MSYEX
Annual or Semi-Annual Statement [Text Block] This semiannual shareholder report contains important information about NYLI MacKay Strategic Bond Fund (the "Fund") for the period November 1, 2024 to April 30, 2025.
Shareholder Report Annual or Semi-Annual semi-annual shareholder report
Additional Information [Text Block] You can find additional information about the Fund at dfinview.com/NYLIM. You can also request this information by contacting us at 800-624-6782.
Additional Information Phone Number 800-624-6782
Additional Information Website dfinview.com/NYLIM
Expenses [Text Block]
What were the Fund costs for the last six months?
(Based on a hypothetical $10,000 investment)
Share Class Name Costs of a $10,000 investment Costs paid as a percentage
of a $10,000 investment1
Class R6 $32 0.63%
1.
Annualized.
Expenses Paid, Amount $ 32
Expense Ratio, Percent 0.63% [6]
Performance Past Does Not Indicate Future [Text] Keep in mind that the Fund ’s past performance is not a good predictor of how the Fund will perform in the future.
Line Graph [Table Text Block]
Fund Performance
The following graph compares the initial and subsequent account values at the end of each of the most recently completed 10 semiannual reporting periods of the Fund (or for the life of the Fund, if shorter). It assumes a $10,000 initial investment at the beginning of the first fiscal period in an appropriate, broad-based securities market index and other additional indexes, if applicable, for the same period and reflects the deduction of all sales charges, where applicable.
Fund Performance - Growth of 10K
Average Annual Return [Table Text Block]
Average Annual Total Returns for the Period Ended April 30, 2025 Inception
Date		 Six
Months1		 One
Year		 Five
Years		 Since
Inception
Class R6 Shares 2/28/2018 3.25% 9.85% 5.05% 3.65%
Bloomberg U.S. Aggregate Bond Index2 2.57% 8.02% (0.67)% 1.69%
Morningstar Multisector Bond Category Average3 2.25% 7.76% 4.19% 2.94%
1.
Not annualized.
2.
The Fund has selected the Bloomberg U.S. Aggregate Bond Index to represent a broad measure of market performance. The Bloomberg U.S. Aggregate Bond Index is a broad-based benchmark that measures the performance of the investment grade, U.S. dollar denominated, fixed-rate taxable bond market, including Treasuries, government-related and corporate securities, mortgage-backed securities (agency fixed-rate and hybrid adjustable rate mortgage pass-throughs), asset-backed securities and commercial mortgage-backed securities.
3.
The Morningstar Multisector Bond Category Average is representative of funds that seek income by diversifying their assets among several fixed-income sectors, usually U.S. government obligations, U.S. corporate bonds, foreign bonds, and high yield U.S. debt securities. These portfolios typically hold 35% to 65% of bond assets in securities that are not rated or are rated by a major agency such as Standard & Poor's or Moody's at the level of BB (considered speculative for taxable bonds) and below. Results are based on average total returns of similar funds with all dividends and capital gain distributions reinvested.
Performance Inception Date Feb. 28, 2018
No Deduction of Taxes [Text Block] The graph and table do not reflect the deduction of taxes that a shareholder would pay on Fund distributions or redemption of Fund shares.
Updated Performance Information Location [Text Block] Visit newyorklifeinvestments.com/funds for the most recent performance information.
Net Assets $ 995,196,754
Holdings Count | Holding 548
Investment Company Portfolio Turnover 85.00%
Additional Fund Statistics [Text Block]
Key Fund Statistics
Fund's net assets $995,196,754%
Total number of portfolio holdings 548%
Portfolio turnover rate 85%
Holdings [Text Block]
Graphical Representation of Holdings
The tables below show the investment makeup of the Fund; percentages indicated are based on the Fund's net assets.
Top Ten Holdings and/or Issuers*
U.S. Treasury Notes, 3.75%-4.625%, due 4/30/27-2/15/35 22.3%
Connecticut Avenue Securities Trust, 6.053%-14.204%, due 9/25/31-1/25/45 3.9%
FHLMC STACR REMIC Trust, 6.004%-11.454%, due 8/25/33-1/25/51 3.5%
GNMA, (zero coupon)-4.50%, due 7/20/44-2/16/66 3.1%
UMBS, 30 Year, 2.00%-5.50%, due 3/1/52-5/1/54 2.5%
Flagship Credit Auto Trust, 1.59%-6.30%, due 3/16/26-4/15/30 2.0%
FHLMC, (zero coupon)-9.304%, due 5/25/44-8/15/56 1.5%
Exeter Automobile Receivables Trust, 3.04%-10.45%, due 12/15/28-9/15/32 1.4%
Wells Fargo Commercial Mortgage Trust, 2.70%-5.122%, due 12/15/39-1/15/60 1.3%
CF Hippolyta Issuer LLC, 1.69%-2.60%, due 7/15/60-3/15/61 1.0%
* Excluding short-term investments
Portfolio Composition 
Corporate Bonds 28.8%
Mortgage-Backed Securities 26.9%
U.S. Government & Federal Agencies 25.3%
Asset-Backed Securities 11.8%
Foreign Government Bonds 4.1%
Loan Assignments 2.0%
Short-Term Investments 1.4%
Common Stocks 0.0%‡
Other Assets, Less Liabilities (0.3)%
‡
Less than one-tenth of a percent.
Largest Holdings [Text Block]
Top Ten Holdings and/or Issuers*
U.S. Treasury Notes, 3.75%-4.625%, due 4/30/27-2/15/35 22.3%
Connecticut Avenue Securities Trust, 6.053%-14.204%, due 9/25/31-1/25/45 3.9%
FHLMC STACR REMIC Trust, 6.004%-11.454%, due 8/25/33-1/25/51 3.5%
GNMA, (zero coupon)-4.50%, due 7/20/44-2/16/66 3.1%
UMBS, 30 Year, 2.00%-5.50%, due 3/1/52-5/1/54 2.5%
Flagship Credit Auto Trust, 1.59%-6.30%, due 3/16/26-4/15/30 2.0%
FHLMC, (zero coupon)-9.304%, due 5/25/44-8/15/56 1.5%
Exeter Automobile Receivables Trust, 3.04%-10.45%, due 12/15/28-9/15/32 1.4%
Wells Fargo Commercial Mortgage Trust, 2.70%-5.122%, due 12/15/39-1/15/60 1.3%
CF Hippolyta Issuer LLC, 1.69%-2.60%, due 7/15/60-3/15/61 1.0%
* Excluding short-term investments
C000060790 [Member]  
Shareholder Report [Line Items]  
Fund Name NYLI MacKay Strategic Bond Fund
Class Name Investor Class
Trading Symbol MSYDX
Annual or Semi-Annual Statement [Text Block] This semiannual shareholder report contains important information about NYLI MacKay Strategic Bond Fund (the "Fund") for the period November 1, 2024 to April 30, 2025.
Shareholder Report Annual or Semi-Annual semi-annual shareholder report
Additional Information [Text Block] You can find additional information about the Fund at dfinview.com/NYLIM. You can also request this information by contacting us at 800-624-6782.
Additional Information Phone Number 800-624-6782
Additional Information Website dfinview.com/NYLIM
Expenses [Text Block]
What were the Fund costs for the last six months?
(Based on a hypothetical $10,000 investment)
Share Class Name Costs of a $10,000 investment Costs paid as a percentage
of a $10,000 investment1,2
Investor Class $62 1.22%
1.
Reflects fee waivers and/or expense reimbursements, without which expenses would have been higher.
2.
Annualized.
Expenses Paid, Amount $ 62
Expense Ratio, Percent 1.22% [7],[8]
Performance Past Does Not Indicate Future [Text] Keep in mind that the Fund ’s past performance is not a good predictor of how the Fund will perform in the future.
Line Graph [Table Text Block]
Fund Performance
The following graph compares the initial and subsequent account values at the end of each of the most recently completed 10 semiannual reporting periods of the Fund (or for the life of the Fund, if shorter). It assumes a $10,000 initial investment at the beginning of the first fiscal period in an appropriate, broad-based securities market index and other additional indexes, if applicable, for the same period and reflects the deduction of all sales charges, where applicable.
Fund Performance - Growth of 10K
Average Annual Return [Table Text Block]
Average Annual Total Returns for the Period Ended April 30, 2025 Inception
Date		 Six
Months1		 One
Year		 Five
Years		 Ten
Years
Investor Class Shares - Including sales charges 2/28/2008 (1.08)% 4.90% 3.44% 2.33%
Investor Class Shares - Excluding sales charges 3.04% 9.27% 4.40% 2.80%
Bloomberg U.S. Aggregate Bond Index2 2.57% 8.02% (0.67)% 1.54%
Morningstar Multisector Bond Category Average3 2.25% 7.76% 4.19% 3.12%
1.
Not annualized.
2.
The Fund has selected the Bloomberg U.S. Aggregate Bond Index to represent a broad measure of market performance. The Bloomberg U.S. Aggregate Bond Index is a broad-based benchmark that measures the performance of the investment grade, U.S. dollar denominated, fixed-rate taxable bond market, including Treasuries, government-related and corporate securities, mortgage-backed securities (agency fixed-rate and hybrid adjustable rate mortgage pass-throughs), asset-backed securities and commercial mortgage-backed securities.
3.
The Morningstar Multisector Bond Category Average is representative of funds that seek income by diversifying their assets among several fixed-income sectors, usually U.S. government obligations, U.S. corporate bonds, foreign bonds, and high yield U.S. debt securities. These portfolios typically hold 35% to 65% of bond assets in securities that are not rated or are rated by a major agency such as Standard & Poor's or Moody's at the level of BB (considered speculative for taxable bonds) and below. Results are based on average total returns of similar funds with all dividends and capital gain distributions reinvested.
Performance Inception Date Feb. 28, 2008
No Deduction of Taxes [Text Block] The graph and table do not reflect the deduction of taxes that a shareholder would pay on Fund distributions or redemption of Fund shares.
Updated Performance Information Location [Text Block] Visit newyorklifeinvestments.com/funds for the most recent performance information.
Net Assets $ 995,196,754
Holdings Count | Holding 548
Investment Company Portfolio Turnover 85.00%
Additional Fund Statistics [Text Block]
Key Fund Statistics
Fund's net assets $995,196,754%
Total number of portfolio holdings 548%
Portfolio turnover rate 85%
Holdings [Text Block]
Graphical Representation of Holdings
The tables below show the investment makeup of the Fund; percentages indicated are based on the Fund's net assets.
Top Ten Holdings and/or Issuers*
U.S. Treasury Notes, 3.75%-4.625%, due 4/30/27-2/15/35 22.3%
Connecticut Avenue Securities Trust, 6.053%-14.204%, due 9/25/31-1/25/45 3.9%
FHLMC STACR REMIC Trust, 6.004%-11.454%, due 8/25/33-1/25/51 3.5%
GNMA, (zero coupon)-4.50%, due 7/20/44-2/16/66 3.1%
UMBS, 30 Year, 2.00%-5.50%, due 3/1/52-5/1/54 2.5%
Flagship Credit Auto Trust, 1.59%-6.30%, due 3/16/26-4/15/30 2.0%
FHLMC, (zero coupon)-9.304%, due 5/25/44-8/15/56 1.5%
Exeter Automobile Receivables Trust, 3.04%-10.45%, due 12/15/28-9/15/32 1.4%
Wells Fargo Commercial Mortgage Trust, 2.70%-5.122%, due 12/15/39-1/15/60 1.3%
CF Hippolyta Issuer LLC, 1.69%-2.60%, due 7/15/60-3/15/61 1.0%
* Excluding short-term investments
Portfolio Composition 
Corporate Bonds 28.8%
Mortgage-Backed Securities 26.9%
U.S. Government & Federal Agencies 25.3%
Asset-Backed Securities 11.8%
Foreign Government Bonds 4.1%
Loan Assignments 2.0%
Short-Term Investments 1.4%
Common Stocks 0.0%‡
Other Assets, Less Liabilities (0.3)%
‡
Less than one-tenth of a percent.
Largest Holdings [Text Block]
Top Ten Holdings and/or Issuers*
U.S. Treasury Notes, 3.75%-4.625%, due 4/30/27-2/15/35 22.3%
Connecticut Avenue Securities Trust, 6.053%-14.204%, due 9/25/31-1/25/45 3.9%
FHLMC STACR REMIC Trust, 6.004%-11.454%, due 8/25/33-1/25/51 3.5%
GNMA, (zero coupon)-4.50%, due 7/20/44-2/16/66 3.1%
UMBS, 30 Year, 2.00%-5.50%, due 3/1/52-5/1/54 2.5%
Flagship Credit Auto Trust, 1.59%-6.30%, due 3/16/26-4/15/30 2.0%
FHLMC, (zero coupon)-9.304%, due 5/25/44-8/15/56 1.5%
Exeter Automobile Receivables Trust, 3.04%-10.45%, due 12/15/28-9/15/32 1.4%
Wells Fargo Commercial Mortgage Trust, 2.70%-5.122%, due 12/15/39-1/15/60 1.3%
CF Hippolyta Issuer LLC, 1.69%-2.60%, due 7/15/60-3/15/61 1.0%
* Excluding short-term investments
C000018689 [Member]  
Shareholder Report [Line Items]  
Fund Name NYLI MacKay U.S. Infrastructure Bond Fund
Class Name Class A
Trading Symbol MGVAX
Annual or Semi-Annual Statement [Text Block] This semiannual shareholder report contains important information about NYLI MacKay U.S. Infrastructure Bond Fund (the "Fund") for the period November 1, 2024 to April 30, 2025.
Shareholder Report Annual or Semi-Annual semi-annual shareholder report
Additional Information [Text Block] You can find additional information about the Fund at dfinview.com/NYLIM. You can also request this information by contacting us at 800-624-6782.
Additional Information Phone Number 800-624-6782
Additional Information Website dfinview.com/NYLIM
Expenses [Text Block]
What were the Fund costs for the last six months?
(Based on a hypothetical $10,000 investment)
Share Class Name Costs of a $10,000 investment Costs paid as a percentage
of a $10,000 investment1,2
Class A $43 0.85%
1.
Reflects fee waivers and/or expense reimbursements, without which expenses would have been higher.
2.
Annualized.
Expenses Paid, Amount $ 43
Expense Ratio, Percent 0.85% [9],[10]
Performance Past Does Not Indicate Future [Text] Keep in mind that the Fund ’s past performance is not a good predictor of how the Fund will perform in the future.
Line Graph [Table Text Block]
Fund Performance
The following graph compares the initial and subsequent account values at the end of each of the most recently completed 10 semiannual reporting periods of the Fund (or for the life of the Fund, if shorter). It assumes a $15,000 initial investment at the beginning of the first fiscal period in an appropriate, broad-based securities market index and other additional indexes, if applicable, for the same period and reflects the deduction of all sales charges, where applicable.
Fund Performance - Growth of 10K
Average Annual Return [Table Text Block]
Average Annual Total Returns for the Period Ended April 30, 2025 Inception
Date		 Six
Months1		 One
Year		 Five
Years		 Ten
Years
Class A Shares - Including sales charges 1/3/1995 (0.12)% 4.70% (0.08)% 1.02%
Class A Shares - Excluding sales charges 2.97% 7.94% 0.85% 1.48%
Bloomberg U.S. Aggregate Bond Index2 2.57% 8.02% (0.67)% 1.54%
Bloomberg 5-10 Year Taxable Municipal Bond Index3 3.44% 8.53% 1.18% 2.76%
Morningstar Intermediate Core Bond Category Average4 2.53% 7.90% (0.29)% 1.48%
1.
Not annualized.
2.
The Fund has selected the Bloomberg U.S. Aggregate Bond Index to represent a broad measure of market performance. The Bloomberg U.S. Aggregate Bond Index is a broad-based benchmark that measures the performance of the investment grade, U.S. dollar-denominated, fixed-rate taxable bond market, including Treasuries, government-related and corporate securities, mortgage-backed securities (agency fixed-rate and hybrid adjustable rate mortgage pass-throughs), asset-backed securities, and commercial mortgage-backed securities.
3.
The Bloomberg 5-10 Year Taxable Municipal Bond Index, which is generally representative of the market sectors or types of investments in which the Fund invests, is the 5-10 year component of the Bloomberg Taxable Municipal Bond Index.
4.
The Morningstar Intermediate Core Bond Category Average is representative of funds that invest primarily in investment-grade U.S. fixed-income issues including government, corporate, and securitized debt, and hold less than 5% in below-investment-grade exposures. Their durations (a measure of interest-rate sensitivity) typically range between 75% and 125% of the three-year average of the effective duration of the Morningstar Core Bond Index. Results are based on average total returns of similar funds with all dividends and capital gain distributions reinvested.
Performance Inception Date Jan. 03, 1995
No Deduction of Taxes [Text Block] The graph and table do not reflect the deduction of taxes that a shareholder would pay on Fund distributions or redemption of Fund shares.
Updated Performance Information Location [Text Block] Visit newyorklifeinvestments.com/funds for the most recent performance information.
Net Assets $ 1,522,704,914
Holdings Count | Holding 386
Investment Company Portfolio Turnover 45.00%
Additional Fund Statistics [Text Block]
Key Fund Statistics
Fund's net assets $1,522,704,914%
Total number of portfolio holdings 386%
Portfolio turnover rate 45%
Holdings [Text Block]
Graphical Representation of Holdings
The tables below show the investment makeup of the Fund; percentages indicated are based on the Fund's net assets.
Top Ten Holdings and/or Issuers*
State of Illinois, 3.45%-7.35%, due 6/15/29-12/1/38 3.5%
State of California, 4.875%-7.55%, due 9/1/29-10/1/41 3.1%
Commonwealth of Massachusetts, 2.663%-5.50%, due 7/15/29-9/1/39 2.8%
City of Los Angeles, 3.258%-5.50%, due 5/15/30-6/1/36 2.4%
New York City Transitional Finance Authority, 2.60%-5.65%, due 5/1/30-11/1/36 2.4%
State of Connecticut, 2.677%-5.099%, due 5/15/30-3/15/34 2.2%
District of Columbia, 5.153%-7.625%, due 5/1/31-10/1/35 2.0%
Alameda Corridor Transportation Authority, (zero coupon)-6.60%, due 10/1/29-10/1/33 1.9%
State of Hawaii, 1.718%-4.936%, due 10/1/30-10/1/38 1.9%
City of New York, 1.623%-5.75%, due 8/1/28-2/1/38 1.8%
* Excluding short-term investments
Portfolio Composition 
Municipal Bonds 91.2%
Corporate Bonds 6.8%
Short-Term Investment 4.5%
Closed-End Fund 0.2%
U.S. Government & Federal Agencies 0.0%‡
Other Assets, Less Liabilities (2.7)%
‡
Less than one-tenth of a percent.
Largest Holdings [Text Block]
Top Ten Holdings and/or Issuers*
State of Illinois, 3.45%-7.35%, due 6/15/29-12/1/38 3.5%
State of California, 4.875%-7.55%, due 9/1/29-10/1/41 3.1%
Commonwealth of Massachusetts, 2.663%-5.50%, due 7/15/29-9/1/39 2.8%
City of Los Angeles, 3.258%-5.50%, due 5/15/30-6/1/36 2.4%
New York City Transitional Finance Authority, 2.60%-5.65%, due 5/1/30-11/1/36 2.4%
State of Connecticut, 2.677%-5.099%, due 5/15/30-3/15/34 2.2%
District of Columbia, 5.153%-7.625%, due 5/1/31-10/1/35 2.0%
Alameda Corridor Transportation Authority, (zero coupon)-6.60%, due 10/1/29-10/1/33 1.9%
State of Hawaii, 1.718%-4.936%, due 10/1/30-10/1/38 1.9%
City of New York, 1.623%-5.75%, due 8/1/28-2/1/38 1.8%
* Excluding short-term investments
C000018691 [Member]  
Shareholder Report [Line Items]  
Fund Name NYLI MacKay U.S. Infrastructure Bond Fund
Class Name Class C
Trading Symbol MGVCX
Annual or Semi-Annual Statement [Text Block] This semiannual shareholder report contains important information about NYLI MacKay U.S. Infrastructure Bond Fund (the "Fund") for the period November 1, 2024 to April 30, 2025.
Shareholder Report Annual or Semi-Annual semi-annual shareholder report
Additional Information [Text Block] You can find additional information about the Fund at dfinview.com/NYLIM. You can also request this information by contacting us at 800-624-6782.
Additional Information Phone Number 800-624-6782
Additional Information Website dfinview.com/NYLIM
Expenses [Text Block]
What were the Fund costs for the last six months?
(Based on a hypothetical $10,000 investment)
Share Class Name Costs of a $10,000 investment Costs paid as a percentage
of a $10,000 investment1,2
Class C $94 1.86%
1.
Reflects fee waivers and/or expense reimbursements, without which expenses would have been higher.
2.
Annualized.
Expenses Paid, Amount $ 94
Expense Ratio, Percent 1.86% [11],[12]
Performance Past Does Not Indicate Future [Text] Keep in mind that the Fund ’s past performance is not a good predictor of how the Fund will perform in the future.
Line Graph [Table Text Block]
Fund Performance
The following graph compares the initial and subsequent account values at the end of each of the most recently completed 10 semiannual reporting periods of the Fund (or for the life of the Fund, if shorter). It assumes a $10,000 initial investment at the beginning of the first fiscal period in an appropriate, broad-based securities market index and other additional indexes, if applicable, for the same period and reflects the deduction of all sales charges, where applicable.
Fund Performance - Growth of 10K
Average Annual Return [Table Text Block]
Average Annual Total Returns for the Period Ended April 30, 2025 Inception
Date		 Six
Months1		 One
Year		 Five
Years		 Ten
Years
Class C Shares - Including sales charges 9/1/1998 1.46% 6.00% (0.18)% 0.45%
Class C Shares - Excluding sales charges 2.46% 7.00% (0.18)% 0.45%
Bloomberg U.S. Aggregate Bond Index2 2.57% 8.02% (0.67)% 1.54%
Bloomberg 5-10 Year Taxable Municipal Bond Index3 3.44% 8.53% 1.18% 2.76%
Morningstar Intermediate Core Bond Category Average4 2.53% 7.90% (0.29)% 1.48%
1.
Not annualized.
2.
The Fund has selected the Bloomberg U.S. Aggregate Bond Index to represent a broad measure of market performance. The Bloomberg U.S. Aggregate Bond Index is a broad-based benchmark that measures the performance of the investment grade, U.S. dollar-denominated, fixed-rate taxable bond market, including Treasuries, government-related and corporate securities, mortgage-backed securities (agency fixed-rate and hybrid adjustable rate mortgage pass-throughs), asset-backed securities, and commercial mortgage-backed securities.
3.
The Bloomberg 5-10 Year Taxable Municipal Bond Index, which is generally representative of the market sectors or types of investments in which the Fund invests, is the 5-10 year component of the Bloomberg Taxable Municipal Bond Index.
4.
The Morningstar Intermediate Core Bond Category Average is representative of funds that invest primarily in investment-grade U.S. fixed-income issues including government, corporate, and securitized debt, and hold less than 5% in below-investment-grade exposures. Their durations (a measure of interest-rate sensitivity) typically range between 75% and 125% of the three-year average of the effective duration of the Morningstar Core Bond Index. Results are based on average total returns of similar funds with all dividends and capital gain distributions reinvested.
Performance Inception Date Sep. 01, 1998
No Deduction of Taxes [Text Block] The graph and table do not reflect the deduction of taxes that a shareholder would pay on Fund distributions or redemption of Fund shares.
Updated Performance Information Location [Text Block] Visit newyorklifeinvestments.com/funds for the most recent performance information.
Net Assets $ 1,522,704,914
Holdings Count | Holding 386
Investment Company Portfolio Turnover 45.00%
Additional Fund Statistics [Text Block]
Key Fund Statistics
Fund's net assets $1,522,704,914%
Total number of portfolio holdings 386%
Portfolio turnover rate 45%
Holdings [Text Block]
Graphical Representation of Holdings
The tables below show the investment makeup of the Fund; percentages indicated are based on the Fund's net assets.
Top Ten Holdings and/or Issuers*
State of Illinois, 3.45%-7.35%, due 6/15/29-12/1/38 3.5%
State of California, 4.875%-7.55%, due 9/1/29-10/1/41 3.1%
Commonwealth of Massachusetts, 2.663%-5.50%, due 7/15/29-9/1/39 2.8%
City of Los Angeles, 3.258%-5.50%, due 5/15/30-6/1/36 2.4%
New York City Transitional Finance Authority, 2.60%-5.65%, due 5/1/30-11/1/36 2.4%
State of Connecticut, 2.677%-5.099%, due 5/15/30-3/15/34 2.2%
District of Columbia, 5.153%-7.625%, due 5/1/31-10/1/35 2.0%
Alameda Corridor Transportation Authority, (zero coupon)-6.60%, due 10/1/29-10/1/33 1.9%
State of Hawaii, 1.718%-4.936%, due 10/1/30-10/1/38 1.9%
City of New York, 1.623%-5.75%, due 8/1/28-2/1/38 1.8%
* Excluding short-term investments
Portfolio Composition 
Municipal Bonds 91.2%
Corporate Bonds 6.8%
Short-Term Investment 4.5%
Closed-End Fund 0.2%
U.S. Government & Federal Agencies 0.0%‡
Other Assets, Less Liabilities (2.7)%
‡
Less than one-tenth of a percent.
Largest Holdings [Text Block]
Top Ten Holdings and/or Issuers*
State of Illinois, 3.45%-7.35%, due 6/15/29-12/1/38 3.5%
State of California, 4.875%-7.55%, due 9/1/29-10/1/41 3.1%
Commonwealth of Massachusetts, 2.663%-5.50%, due 7/15/29-9/1/39 2.8%
City of Los Angeles, 3.258%-5.50%, due 5/15/30-6/1/36 2.4%
New York City Transitional Finance Authority, 2.60%-5.65%, due 5/1/30-11/1/36 2.4%
State of Connecticut, 2.677%-5.099%, due 5/15/30-3/15/34 2.2%
District of Columbia, 5.153%-7.625%, due 5/1/31-10/1/35 2.0%
Alameda Corridor Transportation Authority, (zero coupon)-6.60%, due 10/1/29-10/1/33 1.9%
State of Hawaii, 1.718%-4.936%, due 10/1/30-10/1/38 1.9%
City of New York, 1.623%-5.75%, due 8/1/28-2/1/38 1.8%
* Excluding short-term investments
C000018692 [Member]  
Shareholder Report [Line Items]  
Fund Name NYLI MacKay U.S. Infrastructure Bond Fund
Class Name Class I
Trading Symbol MGOIX
Annual or Semi-Annual Statement [Text Block] This semiannual shareholder report contains important information about NYLI MacKay U.S. Infrastructure Bond Fund (the "Fund") for the period November 1, 2024 to April 30, 2025.
Shareholder Report Annual or Semi-Annual semi-annual shareholder report
Additional Information [Text Block] You can find additional information about the Fund at dfinview.com/NYLIM. You can also request this information by contacting us at 800-624-6782.
Additional Information Phone Number 800-624-6782
Additional Information Website dfinview.com/NYLIM
Expenses [Text Block]
What were the Fund costs for the last six months?
(Based on a hypothetical $10,000 investment)
Share Class Name Costs of a $10,000 investment Costs paid as a percentage
of a $10,000 investment1,2
Class I $30 0.60%
1.
Reflects fee waivers and/or expense reimbursements, without which expenses would have been higher.
2.
Annualized.
Expenses Paid, Amount $ 30
Expense Ratio, Percent 0.60% [13],[14]
Performance Past Does Not Indicate Future [Text] Keep in mind that the Fund ’s past performance is not a good predictor of how the Fund will perform in the future.
Line Graph [Table Text Block]
Fund Performance
The following graph compares the initial and subsequent account values at the end of each of the most recently completed 10 semiannual reporting periods of the Fund (or for the life of the Fund, if shorter). It assumes a $10,000 initial investment at the beginning of the first fiscal period in an appropriate, broad-based securities market index and other additional indexes, if applicable, for the same period and reflects the deduction of all sales charges, where applicable.
Fund Performance - Growth of 10K
Average Annual Return [Table Text Block]
Average Annual Total Returns for the Period Ended April 30, 2025 Inception
Date		 Six
Months1		 One
Year		 Five
Years		 Ten
Years
Class I Shares 1/2/2004 3.06% 8.26% 1.06% 1.73%
Bloomberg U.S. Aggregate Bond Index2 2.57% 8.02% (0.67)% 1.54%
Bloomberg 5-10 Year Taxable Municipal Bond Index3 3.44% 8.53% 1.18% 2.76%
Morningstar Intermediate Core Bond Category Average4 2.53% 7.90% (0.29)% 1.48%
1.
Not annualized.
2.
The Fund has selected the Bloomberg U.S. Aggregate Bond Index to represent a broad measure of market performance. The Bloomberg U.S. Aggregate Bond Index is a broad-based benchmark that measures the performance of the investment grade, U.S. dollar-denominated, fixed-rate taxable bond market, including Treasuries, government-related and corporate securities, mortgage-backed securities (agency fixed-rate and hybrid adjustable rate mortgage pass-throughs), asset-backed securities, and commercial mortgage-backed securities.
3.
The Bloomberg 5-10 Year Taxable Municipal Bond Index, which is generally representative of the market sectors or types of investments in which the Fund invests, is the 5-10 year component of the Bloomberg Taxable Municipal Bond Index.
4.
The Morningstar Intermediate Core Bond Category Average is representative of funds that invest primarily in investment-grade U.S. fixed-income issues including government, corporate, and securitized debt, and hold less than 5% in below-investment-grade exposures. Their durations (a measure of interest-rate sensitivity) typically range between 75% and 125% of the three-year average of the effective duration of the Morningstar Core Bond Index. Results are based on average total returns of similar funds with all dividends and capital gain distributions reinvested.
Performance Inception Date Jan. 02, 2004
No Deduction of Taxes [Text Block] The graph and table do not reflect the deduction of taxes that a shareholder would pay on Fund distributions or redemption of Fund shares.
Updated Performance Information Location [Text Block] Visit newyorklifeinvestments.com/funds for the most recent performance information.
Net Assets $ 1,522,704,914
Holdings Count | Holding 386
Investment Company Portfolio Turnover 45.00%
Additional Fund Statistics [Text Block]
Key Fund Statistics
Fund's net assets $1,522,704,914%
Total number of portfolio holdings 386%
Portfolio turnover rate 45%
Holdings [Text Block]
Graphical Representation of Holdings
The tables below show the investment makeup of the Fund; percentages indicated are based on the Fund's net assets.
Top Ten Holdings and/or Issuers*
State of Illinois, 3.45%-7.35%, due 6/15/29-12/1/38 3.5%
State of California, 4.875%-7.55%, due 9/1/29-10/1/41 3.1%
Commonwealth of Massachusetts, 2.663%-5.50%, due 7/15/29-9/1/39 2.8%
City of Los Angeles, 3.258%-5.50%, due 5/15/30-6/1/36 2.4%
New York City Transitional Finance Authority, 2.60%-5.65%, due 5/1/30-11/1/36 2.4%
State of Connecticut, 2.677%-5.099%, due 5/15/30-3/15/34 2.2%
District of Columbia, 5.153%-7.625%, due 5/1/31-10/1/35 2.0%
Alameda Corridor Transportation Authority, (zero coupon)-6.60%, due 10/1/29-10/1/33 1.9%
State of Hawaii, 1.718%-4.936%, due 10/1/30-10/1/38 1.9%
City of New York, 1.623%-5.75%, due 8/1/28-2/1/38 1.8%
* Excluding short-term investments
Portfolio Composition 
Municipal Bonds 91.2%
Corporate Bonds 6.8%
Short-Term Investment 4.5%
Closed-End Fund 0.2%
U.S. Government & Federal Agencies 0.0%‡
Other Assets, Less Liabilities (2.7)%
‡
Less than one-tenth of a percent.
Largest Holdings [Text Block]
Top Ten Holdings and/or Issuers*
State of Illinois, 3.45%-7.35%, due 6/15/29-12/1/38 3.5%
State of California, 4.875%-7.55%, due 9/1/29-10/1/41 3.1%
Commonwealth of Massachusetts, 2.663%-5.50%, due 7/15/29-9/1/39 2.8%
City of Los Angeles, 3.258%-5.50%, due 5/15/30-6/1/36 2.4%
New York City Transitional Finance Authority, 2.60%-5.65%, due 5/1/30-11/1/36 2.4%
State of Connecticut, 2.677%-5.099%, due 5/15/30-3/15/34 2.2%
District of Columbia, 5.153%-7.625%, due 5/1/31-10/1/35 2.0%
Alameda Corridor Transportation Authority, (zero coupon)-6.60%, due 10/1/29-10/1/33 1.9%
State of Hawaii, 1.718%-4.936%, due 10/1/30-10/1/38 1.9%
City of New York, 1.623%-5.75%, due 8/1/28-2/1/38 1.8%
* Excluding short-term investments
C000185556 [Member]  
Shareholder Report [Line Items]  
Fund Name NYLI MacKay U.S. Infrastructure Bond Fund
Class Name Class R6
Trading Symbol MGVDX
Annual or Semi-Annual Statement [Text Block] This semiannual shareholder report contains important information about NYLI MacKay U.S. Infrastructure Bond Fund (the "Fund") for the period November 1, 2024 to April 30, 2025.
Shareholder Report Annual or Semi-Annual semi-annual shareholder report
Additional Information [Text Block] You can find additional information about the Fund at dfinview.com/NYLIM. You can also request this information by contacting us at 800-624-6782.
Additional Information Phone Number 800-624-6782
Additional Information Website dfinview.com/NYLIM
Expenses [Text Block]
What were the Fund costs for the last six months?
(Based on a hypothetical $10,000 investment)
Share Class Name Costs of a $10,000 investment Costs paid as a percentage
of a $10,000 investment1
Class R6 $26 0.51%
1.
Annualized.
Expenses Paid, Amount $ 26
Expense Ratio, Percent 0.51% [15]
Performance Past Does Not Indicate Future [Text] Keep in mind that the Fund ’s past performance is not a good predictor of how the Fund will perform in the future.
Line Graph [Table Text Block]
Fund Performance
The following graph compares the initial and subsequent account values at the end of each of the most recently completed 10 semiannual reporting periods of the Fund (or for the life of the Fund, if shorter). It assumes a $10,000 initial investment at the beginning of the first fiscal period in an appropriate, broad-based securities market index and other additional indexes, if applicable, for the same period and reflects the deduction of all sales charges, where applicable.
Fund Performance - Growth of 10K
Average Annual Return [Table Text Block]
Average Annual Total Returns for the Period Ended April 30, 2025 Inception
Date		 Six
Months1		 One
Year		 Five
Years		 Since
Inception
Class R6 Shares 11/1/2019 3.11% 8.34% 1.13% 1.11%
Bloomberg U.S. Aggregate Bond Index2 2.57% 8.02% (0.67)% 0.25%
Bloomberg 5-10 Year Taxable Municipal Bond Index3 3.44% 8.53% 1.18% 1.53%
Morningstar Intermediate Core Bond Category Average4 2.53% 7.90% (0.29)% 0.23%
1.
Not annualized.
2.
The Fund has selected the Bloomberg U.S. Aggregate Bond Index to represent a broad measure of market performance. The Bloomberg U.S. Aggregate Bond Index is a broad-based benchmark that measures the performance of the investment grade, U.S. dollar-denominated, fixed-rate taxable bond market, including Treasuries, government-related and corporate securities, mortgage-backed securities (agency fixed-rate and hybrid adjustable rate mortgage pass-throughs), asset-backed securities, and commercial mortgage-backed securities.
3.
The Bloomberg 5-10 Year Taxable Municipal Bond Index, which is generally representative of the market sectors or types of investments in which the Fund invests, is the 5-10 year component of the Bloomberg Taxable Municipal Bond Index.
4.
The Morningstar Intermediate Core Bond Category Average is representative of funds that invest primarily in investment-grade U.S. fixed-income issues including government, corporate, and securitized debt, and hold less than 5% in below-investment-grade exposures. Their durations (a measure of interest-rate sensitivity) typically range between 75% and 125% of the three-year average of the effective duration of the Morningstar Core Bond Index. Results are based on average total returns of similar funds with all dividends and capital gain distributions reinvested.
Performance Inception Date Nov. 01, 2019
No Deduction of Taxes [Text Block] The graph and table do not reflect the deduction of taxes that a shareholder would pay on Fund distributions or redemption of Fund shares.
Updated Performance Information Location [Text Block] Visit newyorklifeinvestments.com/funds for the most recent performance information.
Net Assets $ 1,522,704,914
Holdings Count | Holding 386
Investment Company Portfolio Turnover 45.00%
Additional Fund Statistics [Text Block]
Key Fund Statistics
Fund's net assets $1,522,704,914%
Total number of portfolio holdings 386%
Portfolio turnover rate 45%
Holdings [Text Block]
Graphical Representation of Holdings
The tables below show the investment makeup of the Fund; percentages indicated are based on the Fund's net assets.
Top Ten Holdings and/or Issuers*
State of Illinois, 3.45%-7.35%, due 6/15/29-12/1/38 3.5%
State of California, 4.875%-7.55%, due 9/1/29-10/1/41 3.1%
Commonwealth of Massachusetts, 2.663%-5.50%, due 7/15/29-9/1/39 2.8%
City of Los Angeles, 3.258%-5.50%, due 5/15/30-6/1/36 2.4%
New York City Transitional Finance Authority, 2.60%-5.65%, due 5/1/30-11/1/36 2.4%
State of Connecticut, 2.677%-5.099%, due 5/15/30-3/15/34 2.2%
District of Columbia, 5.153%-7.625%, due 5/1/31-10/1/35 2.0%
Alameda Corridor Transportation Authority, (zero coupon)-6.60%, due 10/1/29-10/1/33 1.9%
State of Hawaii, 1.718%-4.936%, due 10/1/30-10/1/38 1.9%
City of New York, 1.623%-5.75%, due 8/1/28-2/1/38 1.8%
* Excluding short-term investments
Portfolio Composition 
Municipal Bonds 91.2%
Corporate Bonds 6.8%
Short-Term Investment 4.5%
Closed-End Fund 0.2%
U.S. Government & Federal Agencies 0.0%‡
Other Assets, Less Liabilities (2.7)%
‡
Less than one-tenth of a percent.
Largest Holdings [Text Block]
Top Ten Holdings and/or Issuers*
State of Illinois, 3.45%-7.35%, due 6/15/29-12/1/38 3.5%
State of California, 4.875%-7.55%, due 9/1/29-10/1/41 3.1%
Commonwealth of Massachusetts, 2.663%-5.50%, due 7/15/29-9/1/39 2.8%
City of Los Angeles, 3.258%-5.50%, due 5/15/30-6/1/36 2.4%
New York City Transitional Finance Authority, 2.60%-5.65%, due 5/1/30-11/1/36 2.4%
State of Connecticut, 2.677%-5.099%, due 5/15/30-3/15/34 2.2%
District of Columbia, 5.153%-7.625%, due 5/1/31-10/1/35 2.0%
Alameda Corridor Transportation Authority, (zero coupon)-6.60%, due 10/1/29-10/1/33 1.9%
State of Hawaii, 1.718%-4.936%, due 10/1/30-10/1/38 1.9%
City of New York, 1.623%-5.75%, due 8/1/28-2/1/38 1.8%
* Excluding short-term investments
C000060791 [Member]  
Shareholder Report [Line Items]  
Fund Name NYLI MacKay U.S. Infrastructure Bond Fund
Class Name Investor Class
Trading Symbol MGVNX
Annual or Semi-Annual Statement [Text Block] This semiannual shareholder report contains important information about NYLI MacKay U.S. Infrastructure Bond Fund (the "Fund") for the period November 1, 2024 to April 30, 2025.
Shareholder Report Annual or Semi-Annual semi-annual shareholder report
Additional Information [Text Block] You can find additional information about the Fund at dfinview.com/NYLIM. You can also request this information by contacting us at 800-624-6782.
Additional Information Phone Number 800-624-6782
Additional Information Website dfinview.com/NYLIM
Expenses [Text Block]
What were the Fund costs for the last six months?
(Based on a hypothetical $10,000 investment)
Share Class Name Costs of a $10,000 investment Costs paid as a percentage
of a $10,000 investment1,2
Investor Class $56 1.11%
1.
Reflects fee waivers and/or expense reimbursements, without which expenses would have been higher.
2.
Annualized.
Expenses Paid, Amount $ 56
Expense Ratio, Percent 1.11% [16],[17]
Performance Past Does Not Indicate Future [Text] Keep in mind that the Fund ’s past performance is not a good predictor of how the Fund will perform in the future.
Line Graph [Table Text Block]
Fund Performance
The following graph compares the initial and subsequent account values at the end of each of the most recently completed 10 semiannual reporting periods of the Fund (or for the life of the Fund, if shorter). It assumes a $10,000 initial investment at the beginning of the first fiscal period in an appropriate, broad-based securities market index and other additional indexes, if applicable, for the same period and reflects the deduction of all sales charges, where applicable.
Fund Performance - Growth of 10K
Average Annual Return [Table Text Block]
Average Annual Total Returns for the Period Ended April 30, 2025 Inception
Date		 Six
Months1		 One
Year		 Five
Years		 Ten
Years
Investor Class Shares - Including sales charges 2/28/2008 0.26% 5.06% (0.36)% 0.73%
Investor Class Shares - Excluding sales charges 2.83% 7.75% 0.56% 1.20%
Bloomberg U.S. Aggregate Bond Index2 2.57% 8.02% (0.67)% 1.54%
Bloomberg 5-10 Year Taxable Municipal Bond Index3 3.44% 8.53% 1.18% 2.76%
Morningstar Intermediate Core Bond Category Average4 2.53% 7.90% (0.29)% 1.48%
1.
Not annualized.
2.
The Fund has selected the Bloomberg U.S. Aggregate Bond Index to represent a broad measure of market performance. The Bloomberg U.S. Aggregate Bond Index is a broad-based benchmark that measures the performance of the investment grade, U.S. dollar-denominated, fixed-rate taxable bond market, including Treasuries, government-related and corporate securities, mortgage-backed securities (agency fixed-rate and hybrid adjustable rate mortgage pass-throughs), asset-backed securities, and commercial mortgage-backed securities.
3.
The Bloomberg 5-10 Year Taxable Municipal Bond Index, which is generally representative of the market sectors or types of investments in which the Fund invests, is the 5-10 year component of the Bloomberg Taxable Municipal Bond Index.
4.
The Morningstar Intermediate Core Bond Category Average is representative of funds that invest primarily in investment-grade U.S. fixed-income issues including government, corporate, and securitized debt, and hold less than 5% in below-investment-grade exposures. Their durations (a measure of interest-rate sensitivity) typically range between 75% and 125% of the three-year average of the effective duration of the Morningstar Core Bond Index. Results are based on average total returns of similar funds with all dividends and capital gain distributions reinvested.
Performance Inception Date Feb. 28, 2008
No Deduction of Taxes [Text Block] The graph and table do not reflect the deduction of taxes that a shareholder would pay on Fund distributions or redemption of Fund shares.
Updated Performance Information Location [Text Block] Visit newyorklifeinvestments.com/funds for the most recent performance information.
Net Assets $ 1,522,704,914
Holdings Count | Holding 386
Investment Company Portfolio Turnover 45.00%
Additional Fund Statistics [Text Block]
Key Fund Statistics
Fund's net assets $1,522,704,914%
Total number of portfolio holdings 386%
Portfolio turnover rate 45%
Holdings [Text Block]
Graphical Representation of Holdings
The tables below show the investment makeup of the Fund; percentages indicated are based on the Fund's net assets.
Top Ten Holdings and/or Issuers*
State of Illinois, 3.45%-7.35%, due 6/15/29-12/1/38 3.5%
State of California, 4.875%-7.55%, due 9/1/29-10/1/41 3.1%
Commonwealth of Massachusetts, 2.663%-5.50%, due 7/15/29-9/1/39 2.8%
City of Los Angeles, 3.258%-5.50%, due 5/15/30-6/1/36 2.4%
New York City Transitional Finance Authority, 2.60%-5.65%, due 5/1/30-11/1/36 2.4%
State of Connecticut, 2.677%-5.099%, due 5/15/30-3/15/34 2.2%
District of Columbia, 5.153%-7.625%, due 5/1/31-10/1/35 2.0%
Alameda Corridor Transportation Authority, (zero coupon)-6.60%, due 10/1/29-10/1/33 1.9%
State of Hawaii, 1.718%-4.936%, due 10/1/30-10/1/38 1.9%
City of New York, 1.623%-5.75%, due 8/1/28-2/1/38 1.8%
* Excluding short-term investments
Portfolio Composition 
Municipal Bonds 91.2%
Corporate Bonds 6.8%
Short-Term Investment 4.5%
Closed-End Fund 0.2%
U.S. Government & Federal Agencies 0.0%‡
Other Assets, Less Liabilities (2.7)%
‡
Less than one-tenth of a percent.
Largest Holdings [Text Block]
Top Ten Holdings and/or Issuers*
State of Illinois, 3.45%-7.35%, due 6/15/29-12/1/38 3.5%
State of California, 4.875%-7.55%, due 9/1/29-10/1/41 3.1%
Commonwealth of Massachusetts, 2.663%-5.50%, due 7/15/29-9/1/39 2.8%
City of Los Angeles, 3.258%-5.50%, due 5/15/30-6/1/36 2.4%
New York City Transitional Finance Authority, 2.60%-5.65%, due 5/1/30-11/1/36 2.4%
State of Connecticut, 2.677%-5.099%, due 5/15/30-3/15/34 2.2%
District of Columbia, 5.153%-7.625%, due 5/1/31-10/1/35 2.0%
Alameda Corridor Transportation Authority, (zero coupon)-6.60%, due 10/1/29-10/1/33 1.9%
State of Hawaii, 1.718%-4.936%, due 10/1/30-10/1/38 1.9%
City of New York, 1.623%-5.75%, due 8/1/28-2/1/38 1.8%
* Excluding short-term investments
C000018693 [Member]  
Shareholder Report [Line Items]  
Fund Name NYLI MacKay High Yield Corporate Bond Fund
Class Name Class A
Trading Symbol MHCAX
Annual or Semi-Annual Statement [Text Block] This semiannual shareholder report contains important information about NYLI MacKay High Yield Corporate Bond Fund (the "Fund") for the period November 1, 2024 to April 30, 2025.
Shareholder Report Annual or Semi-Annual semi-annual shareholder report
Additional Information [Text Block] You can find additional information about the Fund at dfinview.com/NYLIM. You can also request this information by contacting us at 800-624-6782.
Additional Information Phone Number 800-624-6782
Additional Information Website dfinview.com/NYLIM
Expenses [Text Block]
What were the Fund costs for the last six months?
(Based on a hypothetical $10,000 investment)
Share Class Name Costs of a $10,000 investment Costs paid as a percentage
of a $10,000 investment1
Class A $49 0.98%
1.
Annualized.
Expenses Paid, Amount $ 49
Expense Ratio, Percent 0.98% [18]
Performance Past Does Not Indicate Future [Text] Keep in mind that the Fund ’s past performance is not a good predictor of how the Fund will perform in the future.
Line Graph [Table Text Block]
Fund Performance
The following graph compares the initial and subsequent account values at the end of each of the most recently completed 10 semiannual reporting periods of the Fund (or for the life of the Fund, if shorter). It assumes a $15,000 initial investment at the beginning of the first fiscal period in an appropriate, broad-based securities market index and other additional indexes, if applicable, for the same period and reflects the deduction of all sales charges, where applicable.
Fund Performance - Growth of 10K
Average Annual Return [Table Text Block]
Average Annual Total Returns for the Period Ended April 30, 2025 Inception
Date		 Six
Months1		 One
Year		 Five
Years		 Ten
Years
Class A Shares - Including sales charges 1/3/1995 (3.36)% 1.38% 4.86% 4.07%
Class A Shares - Excluding sales charges 1.20% 6.16% 5.83% 4.55%
Bloomberg U.S. Aggregate Bond Index2 2.57% 8.02% (0.67)% 1.54%
ICE BofA U.S. High Yield Constrained Index3 1.67% 8.69% 6.40% 4.79%
Morningstar High Yield Bond Category Average4 1.47% 7.52% 6.00% 4.08%
1.
Not annualized.
2.
The Fund has selected the Bloomberg U.S. Aggregate Bond Index to represent a broad measure of market performance. The Bloomberg U.S. Aggregate Bond Index is a broad-based benchmark that measures the performance of the investment grade, U.S. dollar-denominated, fixed-rate taxable bond market, including Treasuries, government-related and corporate securities, mortgage-backed securities (agency fixed-rate and hybrid adjustable rate mortgage pass-throughs), asset-backed securities and commercial mortgage-backed securities.
3.
The ICE BofA U.S. High Yield Constrained Index, which is generally representative of the market sectors or types of investments in which the Fund invests, is a market value-weighted index of all domestic and Yankee high-yield bonds, including deferred interest bonds and payment-in-kind securities. Issuers included in the ICE BofA U.S. High Yield Constrained Index have maturities of one year or more and have a credit rating lower than BBB-/Baa3, but are not in default. No single issuer may constitute greater than 2% of the ICE BofA U.S. High Yield Constrained Index.
4.
The Morningstar High Yield Bond Category Average is representative of funds that concentrate on lower-quality bonds, which are riskier than those of higher-quality companies. These funds primarily invest in U.S. high-income debt securities where at least 65% or more of bond assets are not rated or are rated by a major agency such as Standard & Poor’s or Moody’s at the level of BB and below. Results are based on average total returns of similar funds with all dividends and capital gain distributions reinvested.
Performance Inception Date Jan. 03, 1995
No Deduction of Taxes [Text Block] The graph and table do not reflect the deduction of taxes that a shareholder would pay on Fund distributions or redemption of Fund shares.
Updated Performance Information Location [Text Block] Visit newyorklifeinvestments.com/funds for the most recent performance information.
Net Assets $ 11,114,470,812
Holdings Count | Holding 633
Investment Company Portfolio Turnover 15.00%
Additional Fund Statistics [Text Block]
Key Fund Statistics
Fund's net assets $11,114,470,812%
Total number of portfolio holdings 633%
Portfolio turnover rate 15%
Holdings [Text Block]
Graphical Representation of Holdings
The tables below show the investment makeup of the Fund; percentages indicated are based on the Fund's net assets.
Top Ten Holdings and/or Issuers*
TransDigm, Inc., 4.625%-7.125%, due 11/15/27-1/15/33 2.3%
CCO Holdings LLC, 4.25%-5.375%, due 5/1/27-1/15/34 2.1%
Yum! Brands, Inc., 3.625%-5.375%, due 1/15/30-4/1/32 1.2%
Churchill Downs, Inc., 4.75%-6.75%, due 4/1/27-5/1/31 1.2%
Hilton Domestic Operating Co., Inc., 4.00%-5.875%, due 5/1/28-3/15/33 1.1%
Jane Street Group, 6.125%-7.125%, due 4/30/31-5/1/33 1.0%
LifePoint Health, Inc., 5.375%-11.00%, due 1/15/29-6/1/32 1.0%
Mineral Resources Ltd., 8.00%-9.25%, due 5/1/27-5/1/30 1.0%
1011778 B.C. Unlimited Liability Co., 3.875%-6.125%, due 1/15/28-10/15/30 0.9%
Great Outdoors Group LLC, 7.572%, due 1/23/32 0.9%
* Excluding short-term investments
Portfolio Composition 
Corporate Bonds 85.2%
Loan Assignments 7.7%
Common Stocks 0.6%
Convertible Bonds 0.5%
Exchange-Traded Funds 0.4%
Preferred Stocks 0.3%
Other Assets, Less Liabilities 5.3%
Largest Holdings [Text Block]
Top Ten Holdings and/or Issuers*
TransDigm, Inc., 4.625%-7.125%, due 11/15/27-1/15/33 2.3%
CCO Holdings LLC, 4.25%-5.375%, due 5/1/27-1/15/34 2.1%
Yum! Brands, Inc., 3.625%-5.375%, due 1/15/30-4/1/32 1.2%
Churchill Downs, Inc., 4.75%-6.75%, due 4/1/27-5/1/31 1.2%
Hilton Domestic Operating Co., Inc., 4.00%-5.875%, due 5/1/28-3/15/33 1.1%
Jane Street Group, 6.125%-7.125%, due 4/30/31-5/1/33 1.0%
LifePoint Health, Inc., 5.375%-11.00%, due 1/15/29-6/1/32 1.0%
Mineral Resources Ltd., 8.00%-9.25%, due 5/1/27-5/1/30 1.0%
1011778 B.C. Unlimited Liability Co., 3.875%-6.125%, due 1/15/28-10/15/30 0.9%
Great Outdoors Group LLC, 7.572%, due 1/23/32 0.9%
* Excluding short-term investments
C000018695 [Member]  
Shareholder Report [Line Items]  
Fund Name NYLI MacKay High Yield Corporate Bond Fund
Class Name Class C
Trading Symbol MYHCX
Annual or Semi-Annual Statement [Text Block] This semiannual shareholder report contains important information about NYLI MacKay High Yield Corporate Bond Fund (the "Fund") for the period November 1, 2024 to April 30, 2025.
Shareholder Report Annual or Semi-Annual semi-annual shareholder report
Additional Information [Text Block] You can find additional information about the Fund at dfinview.com/NYLIM. You can also request this information by contacting us at 800-624-6782.
Additional Information Phone Number 800-624-6782
Additional Information Website dfinview.com/NYLIM
Expenses [Text Block]
What were the Fund costs for the last six months?
(Based on a hypothetical $10,000 investment)
Share Class Name Costs of a $10,000 investment Costs paid as a percentage
of a $10,000 investment1
Class C $95 1.91%
1.
Annualized.
Expenses Paid, Amount $ 95
Expense Ratio, Percent 1.91% [19]
Performance Past Does Not Indicate Future [Text] Keep in mind that the Fund ’s past performance is not a good predictor of how the Fund will perform in the future.
Line Graph [Table Text Block]
Fund Performance
The following graph compares the initial and subsequent account values at the end of each of the most recently completed 10 semiannual reporting periods of the Fund (or for the life of the Fund, if shorter). It assumes a $10,000 initial investment at the beginning of the first fiscal period in an appropriate, broad-based securities market index and other additional indexes, if applicable, for the same period and reflects the deduction of all sales charges, where applicable.
Fund Performance - Growth of 10K
Average Annual Return [Table Text Block]
Average Annual Total Returns for the Period Ended April 30, 2025 Inception
Date		 Six
Months1		 One
Year		 Five
Years		 Ten
Years
Class C Shares - Including sales charges 9/1/1998 (0.26)% 4.19% 4.89% 3.67%
Class C Shares - Excluding sales charges 0.73% 5.19% 4.89% 3.67%
Bloomberg U.S. Aggregate Bond Index2 2.57% 8.02% (0.67)% 1.54%
ICE BofA U.S. High Yield Constrained Index3 1.67% 8.69% 6.40% 4.79%
Morningstar High Yield Bond Category Average4 1.47% 7.52% 6.00% 4.08%
1.
Not annualized.
2.
The Fund has selected the Bloomberg U.S. Aggregate Bond Index to represent a broad measure of market performance. The Bloomberg U.S. Aggregate Bond Index is a broad-based benchmark that measures the performance of the investment grade, U.S. dollar-denominated, fixed-rate taxable bond market, including Treasuries, government-related and corporate securities, mortgage-backed securities (agency fixed-rate and hybrid adjustable rate mortgage pass-throughs), asset-backed securities and commercial mortgage-backed securities.
3.
The ICE BofA U.S. High Yield Constrained Index, which is generally representative of the market sectors or types of investments in which the Fund invests, is a market value-weighted index of all domestic and Yankee high-yield bonds, including deferred interest bonds and payment-in-kind securities. Issuers included in the ICE BofA U.S. High Yield Constrained Index have maturities of one year or more and have a credit rating lower than BBB-/Baa3, but are not in default. No single issuer may constitute greater than 2% of the ICE BofA U.S. High Yield Constrained Index.
4.
The Morningstar High Yield Bond Category Average is representative of funds that concentrate on lower-quality bonds, which are riskier than those of higher-quality companies. These funds primarily invest in U.S. high-income debt securities where at least 65% or more of bond assets are not rated or are rated by a major agency such as Standard & Poor’s or Moody’s at the level of BB and below. Results are based on average total returns of similar funds with all dividends and capital gain distributions reinvested.
Performance Inception Date Sep. 01, 1998
No Deduction of Taxes [Text Block] The graph and table do not reflect the deduction of taxes that a shareholder would pay on Fund distributions or redemption of Fund shares.
Updated Performance Information Location [Text Block] Visit newyorklifeinvestments.com/funds for the most recent performance information.
Net Assets $ 11,114,470,812
Holdings Count | Holding 633
Investment Company Portfolio Turnover 15.00%
Additional Fund Statistics [Text Block]
Key Fund Statistics
Fund's net assets $11,114,470,812%
Total number of portfolio holdings 633%
Portfolio turnover rate 15%
Holdings [Text Block]
Graphical Representation of Holdings
The tables below show the investment makeup of the Fund; percentages indicated are based on the Fund's net assets.
Top Ten Holdings and/or Issuers*
TransDigm, Inc., 4.625%-7.125%, due 11/15/27-1/15/33 2.3%
CCO Holdings LLC, 4.25%-5.375%, due 5/1/27-1/15/34 2.1%
Yum! Brands, Inc., 3.625%-5.375%, due 1/15/30-4/1/32 1.2%
Churchill Downs, Inc., 4.75%-6.75%, due 4/1/27-5/1/31 1.2%
Hilton Domestic Operating Co., Inc., 4.00%-5.875%, due 5/1/28-3/15/33 1.1%
Jane Street Group, 6.125%-7.125%, due 4/30/31-5/1/33 1.0%
LifePoint Health, Inc., 5.375%-11.00%, due 1/15/29-6/1/32 1.0%
Mineral Resources Ltd., 8.00%-9.25%, due 5/1/27-5/1/30 1.0%
1011778 B.C. Unlimited Liability Co., 3.875%-6.125%, due 1/15/28-10/15/30 0.9%
Great Outdoors Group LLC, 7.572%, due 1/23/32 0.9%
* Excluding short-term investments
Portfolio Composition 
Corporate Bonds 85.2%
Loan Assignments 7.7%
Common Stocks 0.6%
Convertible Bonds 0.5%
Exchange-Traded Funds 0.4%
Preferred Stocks 0.3%
Other Assets, Less Liabilities 5.3%
Largest Holdings [Text Block]
Top Ten Holdings and/or Issuers*
TransDigm, Inc., 4.625%-7.125%, due 11/15/27-1/15/33 2.3%
CCO Holdings LLC, 4.25%-5.375%, due 5/1/27-1/15/34 2.1%
Yum! Brands, Inc., 3.625%-5.375%, due 1/15/30-4/1/32 1.2%
Churchill Downs, Inc., 4.75%-6.75%, due 4/1/27-5/1/31 1.2%
Hilton Domestic Operating Co., Inc., 4.00%-5.875%, due 5/1/28-3/15/33 1.1%
Jane Street Group, 6.125%-7.125%, due 4/30/31-5/1/33 1.0%
LifePoint Health, Inc., 5.375%-11.00%, due 1/15/29-6/1/32 1.0%
Mineral Resources Ltd., 8.00%-9.25%, due 5/1/27-5/1/30 1.0%
1011778 B.C. Unlimited Liability Co., 3.875%-6.125%, due 1/15/28-10/15/30 0.9%
Great Outdoors Group LLC, 7.572%, due 1/23/32 0.9%
* Excluding short-term investments
C000018696 [Member]  
Shareholder Report [Line Items]  
Fund Name NYLI MacKay High Yield Corporate Bond Fund
Class Name Class I
Trading Symbol MHYIX
Annual or Semi-Annual Statement [Text Block] This semiannual shareholder report contains important information about NYLI MacKay High Yield Corporate Bond Fund (the "Fund") for the period November 1, 2024 to April 30, 2025.
Shareholder Report Annual or Semi-Annual semi-annual shareholder report
Additional Information [Text Block] You can find additional information about the Fund at dfinview.com/NYLIM. You can also request this information by contacting us at 800-624-6782.
Additional Information Phone Number 800-624-6782
Additional Information Website dfinview.com/NYLIM
Expenses [Text Block]
What were the Fund costs for the last six months?
(Based on a hypothetical $10,000 investment)
Share Class Name Costs of a $10,000 investment Costs paid as a percentage
of a $10,000 investment1
Class I $36 0.73%
1.
Annualized.
Expenses Paid, Amount $ 36
Expense Ratio, Percent 0.73% [20]
Performance Past Does Not Indicate Future [Text] Keep in mind that the Fund ’s past performance is not a good predictor of how the Fund will perform in the future.
Line Graph [Table Text Block]
Fund Performance
The following graph compares the initial and subsequent account values at the end of each of the most recently completed 10 semiannual reporting periods of the Fund (or for the life of the Fund, if shorter). It assumes a $10,000 initial investment at the beginning of the first fiscal period in an appropriate, broad-based securities market index and other additional indexes, if applicable, for the same period and reflects the deduction of all sales charges, where applicable.
Fund Performance - Growth of 10K
Average Annual Return [Table Text Block]
Average Annual Total Returns for the Period Ended April 30, 2025 Inception
Date		 Six
Months1		 One
Year		 Five
Years		 Ten
Years
Class I Shares 1/2/2004 1.32% 6.42% 6.09% 4.82%
Bloomberg U.S. Aggregate Bond Index2 2.57% 8.02% (0.67)% 1.54%
ICE BofA U.S. High Yield Constrained Index3 1.67% 8.69% 6.40% 4.79%
Morningstar High Yield Bond Category Average4 1.47% 7.52% 6.00% 4.08%
1.
Not annualized.
2.
The Fund has selected the Bloomberg U.S. Aggregate Bond Index to represent a broad measure of market performance. The Bloomberg U.S. Aggregate Bond Index is a broad-based benchmark that measures the performance of the investment grade, U.S. dollar-denominated, fixed-rate taxable bond market, including Treasuries, government-related and corporate securities, mortgage-backed securities (agency fixed-rate and hybrid adjustable rate mortgage pass-throughs), asset-backed securities and commercial mortgage-backed securities.
3.
The ICE BofA U.S. High Yield Constrained Index, which is generally representative of the market sectors or types of investments in which the Fund invests, is a market value-weighted index of all domestic and Yankee high-yield bonds, including deferred interest bonds and payment-in-kind securities. Issuers included in the ICE BofA U.S. High Yield Constrained Index have maturities of one year or more and have a credit rating lower than BBB-/Baa3, but are not in default. No single issuer may constitute greater than 2% of the ICE BofA U.S. High Yield Constrained Index.
4.
The Morningstar High Yield Bond Category Average is representative of funds that concentrate on lower-quality bonds, which are riskier than those of higher-quality companies. These funds primarily invest in U.S. high-income debt securities where at least 65% or more of bond assets are not rated or are rated by a major agency such as Standard & Poor’s or Moody’s at the level of BB and below. Results are based on average total returns of similar funds with all dividends and capital gain distributions reinvested.
Performance Inception Date Jan. 02, 2004
No Deduction of Taxes [Text Block] The graph and table do not reflect the deduction of taxes that a shareholder would pay on Fund distributions or redemption of Fund shares.
Updated Performance Information Location [Text Block] Visit newyorklifeinvestments.com/funds for the most recent performance information.
Net Assets $ 11,114,470,812
Holdings Count | Holding 633
Investment Company Portfolio Turnover 15.00%
Additional Fund Statistics [Text Block]
Key Fund Statistics
Fund's net assets $11,114,470,812%
Total number of portfolio holdings 633%
Portfolio turnover rate 15%
Holdings [Text Block]
Graphical Representation of Holdings
The tables below show the investment makeup of the Fund; percentages indicated are based on the Fund's net assets.
Top Ten Holdings and/or Issuers*
TransDigm, Inc., 4.625%-7.125%, due 11/15/27-1/15/33 2.3%
CCO Holdings LLC, 4.25%-5.375%, due 5/1/27-1/15/34 2.1%
Yum! Brands, Inc., 3.625%-5.375%, due 1/15/30-4/1/32 1.2%
Churchill Downs, Inc., 4.75%-6.75%, due 4/1/27-5/1/31 1.2%
Hilton Domestic Operating Co., Inc., 4.00%-5.875%, due 5/1/28-3/15/33 1.1%
Jane Street Group, 6.125%-7.125%, due 4/30/31-5/1/33 1.0%
LifePoint Health, Inc., 5.375%-11.00%, due 1/15/29-6/1/32 1.0%
Mineral Resources Ltd., 8.00%-9.25%, due 5/1/27-5/1/30 1.0%
1011778 B.C. Unlimited Liability Co., 3.875%-6.125%, due 1/15/28-10/15/30 0.9%
Great Outdoors Group LLC, 7.572%, due 1/23/32 0.9%
* Excluding short-term investments
Portfolio Composition 
Corporate Bonds 85.2%
Loan Assignments 7.7%
Common Stocks 0.6%
Convertible Bonds 0.5%
Exchange-Traded Funds 0.4%
Preferred Stocks 0.3%
Other Assets, Less Liabilities 5.3%
Largest Holdings [Text Block]
Top Ten Holdings and/or Issuers*
TransDigm, Inc., 4.625%-7.125%, due 11/15/27-1/15/33 2.3%
CCO Holdings LLC, 4.25%-5.375%, due 5/1/27-1/15/34 2.1%
Yum! Brands, Inc., 3.625%-5.375%, due 1/15/30-4/1/32 1.2%
Churchill Downs, Inc., 4.75%-6.75%, due 4/1/27-5/1/31 1.2%
Hilton Domestic Operating Co., Inc., 4.00%-5.875%, due 5/1/28-3/15/33 1.1%
Jane Street Group, 6.125%-7.125%, due 4/30/31-5/1/33 1.0%
LifePoint Health, Inc., 5.375%-11.00%, due 1/15/29-6/1/32 1.0%
Mineral Resources Ltd., 8.00%-9.25%, due 5/1/27-5/1/30 1.0%
1011778 B.C. Unlimited Liability Co., 3.875%-6.125%, due 1/15/28-10/15/30 0.9%
Great Outdoors Group LLC, 7.572%, due 1/23/32 0.9%
* Excluding short-term investments
C000057099 [Member]  
Shareholder Report [Line Items]  
Fund Name NYLI MacKay High Yield Corporate Bond Fund
Class Name Class R2
Trading Symbol MHYRX
Annual or Semi-Annual Statement [Text Block] This semiannual shareholder report contains important information about NYLI MacKay High Yield Corporate Bond Fund (the "Fund") for the period November 1, 2024 to April 30, 2025.
Shareholder Report Annual or Semi-Annual semi-annual shareholder report
Additional Information [Text Block] You can find additional information about the Fund at dfinview.com/NYLIM. You can also request this information by contacting us at 800-624-6782.
Additional Information Phone Number 800-624-6782
Additional Information Website dfinview.com/NYLIM
Expenses [Text Block]
What were the Fund costs for the last six months?
(Based on a hypothetical $10,000 investment)
Share Class Name Costs of a $10,000 investment Costs paid as a percentage
of a $10,000 investment1
Class R2 $54 1.08%
1.
Annualized.
Expenses Paid, Amount $ 54
Expense Ratio, Percent 1.08% [21]
Performance Past Does Not Indicate Future [Text] Keep in mind that the Fund ’s past performance is not a good predictor of how the Fund will perform in the future.
Line Graph [Table Text Block]
Fund Performance
The following graph compares the initial and subsequent account values at the end of each of the most recently completed 10 semiannual reporting periods of the Fund (or for the life of the Fund, if shorter). It assumes a $10,000 initial investment at the beginning of the first fiscal period in an appropriate, broad-based securities market index and other additional indexes, if applicable, for the same period and reflects the deduction of all sales charges, where applicable.
Fund Performance - Growth of 10K
Average Annual Return [Table Text Block]
Average Annual Total Returns for the Period Ended April 30, 2025 Inception
Date		 Six
Months1		 One
Year		 Five
Years		 Ten
Years
Class R2 Shares 5/1/2008 1.14% 6.05% 5.72% 4.45%
Bloomberg U.S. Aggregate Bond Index2 2.57% 8.02% (0.67)% 1.54%
ICE BofA U.S. High Yield Constrained Index3 1.67% 8.69% 6.40% 4.79%
Morningstar High Yield Bond Category Average4 1.47% 7.52% 6.00% 4.08%
1.
Not annualized.
2.
The Fund has selected the Bloomberg U.S. Aggregate Bond Index to represent a broad measure of market performance. The Bloomberg U.S. Aggregate Bond Index is a broad-based benchmark that measures the performance of the investment grade, U.S. dollar-denominated, fixed-rate taxable bond market, including Treasuries, government-related and corporate securities, mortgage-backed securities (agency fixed-rate and hybrid adjustable rate mortgage pass-throughs), asset-backed securities and commercial mortgage-backed securities.
3.
The ICE BofA U.S. High Yield Constrained Index, which is generally representative of the market sectors or types of investments in which the Fund invests, is a market value-weighted index of all domestic and Yankee high-yield bonds, including deferred interest bonds and payment-in-kind securities. Issuers included in the ICE BofA U.S. High Yield Constrained Index have maturities of one year or more and have a credit rating lower than BBB-/Baa3, but are not in default. No single issuer may constitute greater than 2% of the ICE BofA U.S. High Yield Constrained Index.
4.
The Morningstar High Yield Bond Category Average is representative of funds that concentrate on lower-quality bonds, which are riskier than those of higher-quality companies. These funds primarily invest in U.S. high-income debt securities where at least 65% or more of bond assets are not rated or are rated by a major agency such as Standard & Poor’s or Moody’s at the level of BB and below. Results are based on average total returns of similar funds with all dividends and capital gain distributions reinvested.
Performance Inception Date May 01, 2008
No Deduction of Taxes [Text Block] The graph and table do not reflect the deduction of taxes that a shareholder would pay on Fund distributions or redemption of Fund shares.
Updated Performance Information Location [Text Block] Visit newyorklifeinvestments.com/funds for the most recent performance information.
Net Assets $ 11,114,470,812
Holdings Count | Holding 633
Investment Company Portfolio Turnover 15.00%
Additional Fund Statistics [Text Block]
Key Fund Statistics
Fund's net assets $11,114,470,812%
Total number of portfolio holdings 633%
Portfolio turnover rate 15%
Holdings [Text Block]
Graphical Representation of Holdings
The tables below show the investment makeup of the Fund; percentages indicated are based on the Fund's net assets.
Top Ten Holdings and/or Issuers*
TransDigm, Inc., 4.625%-7.125%, due 11/15/27-1/15/33 2.3%
CCO Holdings LLC, 4.25%-5.375%, due 5/1/27-1/15/34 2.1%
Yum! Brands, Inc., 3.625%-5.375%, due 1/15/30-4/1/32 1.2%
Churchill Downs, Inc., 4.75%-6.75%, due 4/1/27-5/1/31 1.2%
Hilton Domestic Operating Co., Inc., 4.00%-5.875%, due 5/1/28-3/15/33 1.1%
Jane Street Group, 6.125%-7.125%, due 4/30/31-5/1/33 1.0%
LifePoint Health, Inc., 5.375%-11.00%, due 1/15/29-6/1/32 1.0%
Mineral Resources Ltd., 8.00%-9.25%, due 5/1/27-5/1/30 1.0%
1011778 B.C. Unlimited Liability Co., 3.875%-6.125%, due 1/15/28-10/15/30 0.9%
Great Outdoors Group LLC, 7.572%, due 1/23/32 0.9%
* Excluding short-term investments
Portfolio Composition 
Corporate Bonds 85.2%
Loan Assignments 7.7%
Common Stocks 0.6%
Convertible Bonds 0.5%
Exchange-Traded Funds 0.4%
Preferred Stocks 0.3%
Other Assets, Less Liabilities 5.3%
Largest Holdings [Text Block]
Top Ten Holdings and/or Issuers*
TransDigm, Inc., 4.625%-7.125%, due 11/15/27-1/15/33 2.3%
CCO Holdings LLC, 4.25%-5.375%, due 5/1/27-1/15/34 2.1%
Yum! Brands, Inc., 3.625%-5.375%, due 1/15/30-4/1/32 1.2%
Churchill Downs, Inc., 4.75%-6.75%, due 4/1/27-5/1/31 1.2%
Hilton Domestic Operating Co., Inc., 4.00%-5.875%, due 5/1/28-3/15/33 1.1%
Jane Street Group, 6.125%-7.125%, due 4/30/31-5/1/33 1.0%
LifePoint Health, Inc., 5.375%-11.00%, due 1/15/29-6/1/32 1.0%
Mineral Resources Ltd., 8.00%-9.25%, due 5/1/27-5/1/30 1.0%
1011778 B.C. Unlimited Liability Co., 3.875%-6.125%, due 1/15/28-10/15/30 0.9%
Great Outdoors Group LLC, 7.572%, due 1/23/32 0.9%
* Excluding short-term investments
C000166835 [Member]  
Shareholder Report [Line Items]  
Fund Name NYLI MacKay High Yield Corporate Bond Fund
Class Name Class R3
Trading Symbol MHYTX
Annual or Semi-Annual Statement [Text Block] This semiannual shareholder report contains important information about NYLI MacKay High Yield Corporate Bond Fund (the "Fund") for the period November 1, 2024 to April 30, 2025.
Shareholder Report Annual or Semi-Annual semi-annual shareholder report
Additional Information [Text Block] You can find additional information about the Fund at dfinview.com/NYLIM. You can also request this information by contacting us at 800-624-6782.
Additional Information Phone Number 800-624-6782
Additional Information Website dfinview.com/NYLIM
Expenses [Text Block]
What were the Fund costs for the last six months?
(Based on a hypothetical $10,000 investment)
Share Class Name Costs of a $10,000 investment Costs paid as a percentage
of a $10,000 investment1
Class R3 $66 1.33%
1.
Annualized.
Expenses Paid, Amount $ 66
Expense Ratio, Percent 1.33% [22]
Performance Past Does Not Indicate Future [Text] Keep in mind that the Fund ’s past performance is not a good predictor of how the Fund will perform in the future.
Line Graph [Table Text Block]
Fund Performance
The following graph compares the initial and subsequent account values at the end of each of the most recently completed 10 semiannual reporting periods of the Fund (or for the life of the Fund, if shorter). It assumes a $10,000 initial investment at the beginning of the first fiscal period in an appropriate, broad-based securities market index and other additional indexes, if applicable, for the same period and reflects the deduction of all sales charges, where applicable.
Fund Performance - Growth of 10K
Average Annual Return [Table Text Block]
Average Annual Total Returns for the Period Ended April 30, 2025 Inception
Date		 Six
Months1		 One
Year		 Five
Years		 Since
Inception
Class R3 Shares 2/29/2016 1.02% 5.80% 5.42% 5.37%
Bloomberg U.S. Aggregate Bond Index2 2.57% 8.02% (0.67)% 1.53%
ICE BofA U.S. High Yield Constrained Index3 1.67% 8.69% 6.40% 6.34%
Morningstar High Yield Bond Category Average4 1.47% 7.52% 6.00% 5.19%
1.
Not annualized.
2.
The Fund has selected the Bloomberg U.S. Aggregate Bond Index to represent a broad measure of market performance. The Bloomberg U.S. Aggregate Bond Index is a broad-based benchmark that measures the performance of the investment grade, U.S. dollar-denominated, fixed-rate taxable bond market, including Treasuries, government-related and corporate securities, mortgage-backed securities (agency fixed-rate and hybrid adjustable rate mortgage pass-throughs), asset-backed securities and commercial mortgage-backed securities.
3.
The ICE BofA U.S. High Yield Constrained Index, which is generally representative of the market sectors or types of investments in which the Fund invests, is a market value-weighted index of all domestic and Yankee high-yield bonds, including deferred interest bonds and payment-in-kind securities. Issuers included in the ICE BofA U.S. High Yield Constrained Index have maturities of one year or more and have a credit rating lower than BBB-/Baa3, but are not in default. No single issuer may constitute greater than 2% of the ICE BofA U.S. High Yield Constrained Index.
4.
The Morningstar High Yield Bond Category Average is representative of funds that concentrate on lower-quality bonds, which are riskier than those of higher-quality companies. These funds primarily invest in U.S. high-income debt securities where at least 65% or more of bond assets are not rated or are rated by a major agency such as Standard & Poor’s or Moody’s at the level of BB and below. Results are based on average total returns of similar funds with all dividends and capital gain distributions reinvested.
Performance Inception Date Feb. 29, 2016
No Deduction of Taxes [Text Block] The graph and table do not reflect the deduction of taxes that a shareholder would pay on Fund distributions or redemption of Fund shares.
Updated Performance Information Location [Text Block] Visit newyorklifeinvestments.com/funds for the most recent performance information.
Net Assets $ 11,114,470,812
Holdings Count | Holding 633
Investment Company Portfolio Turnover 15.00%
Additional Fund Statistics [Text Block]
Key Fund Statistics
Fund's net assets $11,114,470,812%
Total number of portfolio holdings 633%
Portfolio turnover rate 15%
Holdings [Text Block]
Graphical Representation of Holdings
The tables below show the investment makeup of the Fund; percentages indicated are based on the Fund's net assets.
Top Ten Holdings and/or Issuers*
TransDigm, Inc., 4.625%-7.125%, due 11/15/27-1/15/33 2.3%
CCO Holdings LLC, 4.25%-5.375%, due 5/1/27-1/15/34 2.1%
Yum! Brands, Inc., 3.625%-5.375%, due 1/15/30-4/1/32 1.2%
Churchill Downs, Inc., 4.75%-6.75%, due 4/1/27-5/1/31 1.2%
Hilton Domestic Operating Co., Inc., 4.00%-5.875%, due 5/1/28-3/15/33 1.1%
Jane Street Group, 6.125%-7.125%, due 4/30/31-5/1/33 1.0%
LifePoint Health, Inc., 5.375%-11.00%, due 1/15/29-6/1/32 1.0%
Mineral Resources Ltd., 8.00%-9.25%, due 5/1/27-5/1/30 1.0%
1011778 B.C. Unlimited Liability Co., 3.875%-6.125%, due 1/15/28-10/15/30 0.9%
Great Outdoors Group LLC, 7.572%, due 1/23/32 0.9%
* Excluding short-term investments
Portfolio Composition 
Corporate Bonds 85.2%
Loan Assignments 7.7%
Common Stocks 0.6%
Convertible Bonds 0.5%
Exchange-Traded Funds 0.4%
Preferred Stocks 0.3%
Other Assets, Less Liabilities 5.3%
Largest Holdings [Text Block]
Top Ten Holdings and/or Issuers*
TransDigm, Inc., 4.625%-7.125%, due 11/15/27-1/15/33 2.3%
CCO Holdings LLC, 4.25%-5.375%, due 5/1/27-1/15/34 2.1%
Yum! Brands, Inc., 3.625%-5.375%, due 1/15/30-4/1/32 1.2%
Churchill Downs, Inc., 4.75%-6.75%, due 4/1/27-5/1/31 1.2%
Hilton Domestic Operating Co., Inc., 4.00%-5.875%, due 5/1/28-3/15/33 1.1%
Jane Street Group, 6.125%-7.125%, due 4/30/31-5/1/33 1.0%
LifePoint Health, Inc., 5.375%-11.00%, due 1/15/29-6/1/32 1.0%
Mineral Resources Ltd., 8.00%-9.25%, due 5/1/27-5/1/30 1.0%
1011778 B.C. Unlimited Liability Co., 3.875%-6.125%, due 1/15/28-10/15/30 0.9%
Great Outdoors Group LLC, 7.572%, due 1/23/32 0.9%
* Excluding short-term investments
C000127160 [Member]  
Shareholder Report [Line Items]  
Fund Name NYLI MacKay High Yield Corporate Bond Fund
Class Name Class R6
Trading Symbol MHYSX
Annual or Semi-Annual Statement [Text Block] This semiannual shareholder report contains important information about NYLI MacKay High Yield Corporate Bond Fund (the "Fund") for the period November 1, 2024 to April 30, 2025.
Shareholder Report Annual or Semi-Annual semi-annual shareholder report
Additional Information [Text Block] You can find additional information about the Fund at dfinview.com/NYLIM. You can also request this information by contacting us at 800-624-6782.
Additional Information Phone Number 800-624-6782
Additional Information Website dfinview.com/NYLIM
Expenses [Text Block]
What were the Fund costs for the last six months?
(Based on a hypothetical $10,000 investment)
Share Class Name Costs of a $10,000 investment Costs paid as a percentage
of a $10,000 investment1
Class R6 $28 0.56%
1.
Annualized.
Expenses Paid, Amount $ 28
Expense Ratio, Percent 0.56% [23]
Performance Past Does Not Indicate Future [Text] Keep in mind that the Fund ’s past performance is not a good predictor of how the Fund will perform in the future.
Line Graph [Table Text Block]
Fund Performance
The following graph compares the initial and subsequent account values at the end of each of the most recently completed 10 semiannual reporting periods of the Fund (or for the life of the Fund, if shorter). It assumes a $10,000 initial investment at the beginning of the first fiscal period in an appropriate, broad-based securities market index and other additional indexes, if applicable, for the same period and reflects the deduction of all sales charges, where applicable.
Fund Performance - Growth of 10K
Average Annual Return [Table Text Block]
Average Annual Total Returns for the Period Ended April 30, 2025 Inception
Date		 Six
Months1		 One
Year		 Five
Years		 Ten
Years
Class R6 Shares 6/17/2013 1.40% 6.61% 6.23% 4.95%
Bloomberg U.S. Aggregate Bond Index2 2.57% 8.02% (0.67)% 1.54%
ICE BofA U.S. High Yield Constrained Index3 1.67% 8.69% 6.40% 4.79%
Morningstar High Yield Bond Category Average4 1.47% 7.52% 6.00% 4.08%
1.
Not annualized.
2.
The Fund has selected the Bloomberg U.S. Aggregate Bond Index to represent a broad measure of market performance. The Bloomberg U.S. Aggregate Bond Index is a broad-based benchmark that measures the performance of the investment grade, U.S. dollar-denominated, fixed-rate taxable bond market, including Treasuries, government-related and corporate securities, mortgage-backed securities (agency fixed-rate and hybrid adjustable rate mortgage pass-throughs), asset-backed securities and commercial mortgage-backed securities.
3.
The ICE BofA U.S. High Yield Constrained Index, which is generally representative of the market sectors or types of investments in which the Fund invests, is a market value-weighted index of all domestic and Yankee high-yield bonds, including deferred interest bonds and payment-in-kind securities. Issuers included in the ICE BofA U.S. High Yield Constrained Index have maturities of one year or more and have a credit rating lower than BBB-/Baa3, but are not in default. No single issuer may constitute greater than 2% of the ICE BofA U.S. High Yield Constrained Index.
4.
The Morningstar High Yield Bond Category Average is representative of funds that concentrate on lower-quality bonds, which are riskier than those of higher-quality companies. These funds primarily invest in U.S. high-income debt securities where at least 65% or more of bond assets are not rated or are rated by a major agency such as Standard & Poor’s or Moody’s at the level of BB and below. Results are based on average total returns of similar funds with all dividends and capital gain distributions reinvested.
Performance Inception Date Jun. 17, 2013
No Deduction of Taxes [Text Block] The graph and table do not reflect the deduction of taxes that a shareholder would pay on Fund distributions or redemption of Fund shares.
Updated Performance Information Location [Text Block] Visit newyorklifeinvestments.com/funds for the most recent performance information.
Net Assets $ 11,114,470,812
Holdings Count | Holding 633
Investment Company Portfolio Turnover 15.00%
Additional Fund Statistics [Text Block]
Key Fund Statistics
Fund's net assets $11,114,470,812%
Total number of portfolio holdings 633%
Portfolio turnover rate 15%
Holdings [Text Block]
Graphical Representation of Holdings
The tables below show the investment makeup of the Fund; percentages indicated are based on the Fund's net assets.
Top Ten Holdings and/or Issuers*
TransDigm, Inc., 4.625%-7.125%, due 11/15/27-1/15/33 2.3%
CCO Holdings LLC, 4.25%-5.375%, due 5/1/27-1/15/34 2.1%
Yum! Brands, Inc., 3.625%-5.375%, due 1/15/30-4/1/32 1.2%
Churchill Downs, Inc., 4.75%-6.75%, due 4/1/27-5/1/31 1.2%
Hilton Domestic Operating Co., Inc., 4.00%-5.875%, due 5/1/28-3/15/33 1.1%
Jane Street Group, 6.125%-7.125%, due 4/30/31-5/1/33 1.0%
LifePoint Health, Inc., 5.375%-11.00%, due 1/15/29-6/1/32 1.0%
Mineral Resources Ltd., 8.00%-9.25%, due 5/1/27-5/1/30 1.0%
1011778 B.C. Unlimited Liability Co., 3.875%-6.125%, due 1/15/28-10/15/30 0.9%
Great Outdoors Group LLC, 7.572%, due 1/23/32 0.9%
* Excluding short-term investments
Portfolio Composition 
Corporate Bonds 85.2%
Loan Assignments 7.7%
Common Stocks 0.6%
Convertible Bonds 0.5%
Exchange-Traded Funds 0.4%
Preferred Stocks 0.3%
Other Assets, Less Liabilities 5.3%
Largest Holdings [Text Block]
Top Ten Holdings and/or Issuers*
TransDigm, Inc., 4.625%-7.125%, due 11/15/27-1/15/33 2.3%
CCO Holdings LLC, 4.25%-5.375%, due 5/1/27-1/15/34 2.1%
Yum! Brands, Inc., 3.625%-5.375%, due 1/15/30-4/1/32 1.2%
Churchill Downs, Inc., 4.75%-6.75%, due 4/1/27-5/1/31 1.2%
Hilton Domestic Operating Co., Inc., 4.00%-5.875%, due 5/1/28-3/15/33 1.1%
Jane Street Group, 6.125%-7.125%, due 4/30/31-5/1/33 1.0%
LifePoint Health, Inc., 5.375%-11.00%, due 1/15/29-6/1/32 1.0%
Mineral Resources Ltd., 8.00%-9.25%, due 5/1/27-5/1/30 1.0%
1011778 B.C. Unlimited Liability Co., 3.875%-6.125%, due 1/15/28-10/15/30 0.9%
Great Outdoors Group LLC, 7.572%, due 1/23/32 0.9%
* Excluding short-term investments
C000060792 [Member]  
Shareholder Report [Line Items]  
Fund Name NYLI MacKay High Yield Corporate Bond Fund
Class Name Investor Class
Trading Symbol MHHIX
Annual or Semi-Annual Statement [Text Block] This semiannual shareholder report contains important information about NYLI MacKay High Yield Corporate Bond Fund (the "Fund") for the period November 1, 2024 to April 30, 2025.
Shareholder Report Annual or Semi-Annual semi-annual shareholder report
Additional Information [Text Block] You can find additional information about the Fund at dfinview.com/NYLIM. You can also request this information by contacting us at 800-624-6782.
Additional Information Phone Number 800-624-6782
Additional Information Website dfinview.com/NYLIM
Expenses [Text Block]
What were the Fund costs for the last six months?
(Based on a hypothetical $10,000 investment)
Share Class Name Costs of a $10,000 investment Costs paid as a percentage
of a $10,000 investment1
Investor Class $58 1.16%
1.
Annualized.
Expenses Paid, Amount $ 58
Expense Ratio, Percent 1.16% [24]
Performance Past Does Not Indicate Future [Text] Keep in mind that the Fund ’s past performance is not a good predictor of how the Fund will perform in the future.
Line Graph [Table Text Block]
Fund Performance
The following graph compares the initial and subsequent account values at the end of each of the most recently completed 10 semiannual reporting periods of the Fund (or for the life of the Fund, if shorter). It assumes a $10,000 initial investment at the beginning of the first fiscal period in an appropriate, broad-based securities market index and other additional indexes, if applicable, for the same period and reflects the deduction of all sales charges, where applicable.
Fund Performance - Growth of 10K
Average Annual Return [Table Text Block]
Average Annual Total Returns for the Period Ended April 30, 2025 Inception
Date		 Six
Months1		 One
Year		 Five
Years		 Ten
Years
Investor Class Shares - Including sales charges 2/28/2008 (2.95)% 1.68% 4.69% 3.97%
Investor Class Shares - Excluding sales charges 1.09% 5.91% 5.66% 4.45%
Bloomberg U.S. Aggregate Bond Index2 2.57% 8.02% (0.67)% 1.54%
ICE BofA U.S. High Yield Constrained Index3 1.67% 8.69% 6.40% 4.79%
Morningstar High Yield Bond Category Average4 1.47% 7.52% 6.00% 4.08%
1.
Not annualized.
2.
The Fund has selected the Bloomberg U.S. Aggregate Bond Index to represent a broad measure of market performance. The Bloomberg U.S. Aggregate Bond Index is a broad-based benchmark that measures the performance of the investment grade, U.S. dollar-denominated, fixed-rate taxable bond market, including Treasuries, government-related and corporate securities, mortgage-backed securities (agency fixed-rate and hybrid adjustable rate mortgage pass-throughs), asset-backed securities and commercial mortgage-backed securities.
3.
The ICE BofA U.S. High Yield Constrained Index, which is generally representative of the market sectors or types of investments in which the Fund invests, is a market value-weighted index of all domestic and Yankee high-yield bonds, including deferred interest bonds and payment-in-kind securities. Issuers included in the ICE BofA U.S. High Yield Constrained Index have maturities of one year or more and have a credit rating lower than BBB-/Baa3, but are not in default. No single issuer may constitute greater than 2% of the ICE BofA U.S. High Yield Constrained Index.
4.
The Morningstar High Yield Bond Category Average is representative of funds that concentrate on lower-quality bonds, which are riskier than those of higher-quality companies. These funds primarily invest in U.S. high-income debt securities where at least 65% or more of bond assets are not rated or are rated by a major agency such as Standard & Poor’s or Moody’s at the level of BB and below. Results are based on average total returns of similar funds with all dividends and capital gain distributions reinvested.
Performance Inception Date Feb. 28, 2008
No Deduction of Taxes [Text Block] The graph and table do not reflect the deduction of taxes that a shareholder would pay on Fund distributions or redemption of Fund shares.
Updated Performance Information Location [Text Block] Visit newyorklifeinvestments.com/funds for the most recent performance information.
Net Assets $ 11,114,470,812
Holdings Count | Holding 633
Investment Company Portfolio Turnover 15.00%
Additional Fund Statistics [Text Block]
Key Fund Statistics
Fund's net assets $11,114,470,812%
Total number of portfolio holdings 633%
Portfolio turnover rate 15%
Holdings [Text Block]
Graphical Representation of Holdings
The tables below show the investment makeup of the Fund; percentages indicated are based on the Fund's net assets.
Top Ten Holdings and/or Issuers*
TransDigm, Inc., 4.625%-7.125%, due 11/15/27-1/15/33 2.3%
CCO Holdings LLC, 4.25%-5.375%, due 5/1/27-1/15/34 2.1%
Yum! Brands, Inc., 3.625%-5.375%, due 1/15/30-4/1/32 1.2%
Churchill Downs, Inc., 4.75%-6.75%, due 4/1/27-5/1/31 1.2%
Hilton Domestic Operating Co., Inc., 4.00%-5.875%, due 5/1/28-3/15/33 1.1%
Jane Street Group, 6.125%-7.125%, due 4/30/31-5/1/33 1.0%
LifePoint Health, Inc., 5.375%-11.00%, due 1/15/29-6/1/32 1.0%
Mineral Resources Ltd., 8.00%-9.25%, due 5/1/27-5/1/30 1.0%
1011778 B.C. Unlimited Liability Co., 3.875%-6.125%, due 1/15/28-10/15/30 0.9%
Great Outdoors Group LLC, 7.572%, due 1/23/32 0.9%
* Excluding short-term investments
Portfolio Composition 
Corporate Bonds 85.2%
Loan Assignments 7.7%
Common Stocks 0.6%
Convertible Bonds 0.5%
Exchange-Traded Funds 0.4%
Preferred Stocks 0.3%
Other Assets, Less Liabilities 5.3%
Largest Holdings [Text Block]
Top Ten Holdings and/or Issuers*
TransDigm, Inc., 4.625%-7.125%, due 11/15/27-1/15/33 2.3%
CCO Holdings LLC, 4.25%-5.375%, due 5/1/27-1/15/34 2.1%
Yum! Brands, Inc., 3.625%-5.375%, due 1/15/30-4/1/32 1.2%
Churchill Downs, Inc., 4.75%-6.75%, due 4/1/27-5/1/31 1.2%
Hilton Domestic Operating Co., Inc., 4.00%-5.875%, due 5/1/28-3/15/33 1.1%
Jane Street Group, 6.125%-7.125%, due 4/30/31-5/1/33 1.0%
LifePoint Health, Inc., 5.375%-11.00%, due 1/15/29-6/1/32 1.0%
Mineral Resources Ltd., 8.00%-9.25%, due 5/1/27-5/1/30 1.0%
1011778 B.C. Unlimited Liability Co., 3.875%-6.125%, due 1/15/28-10/15/30 0.9%
Great Outdoors Group LLC, 7.572%, due 1/23/32 0.9%
* Excluding short-term investments
C000221691 [Member]  
Shareholder Report [Line Items]  
Fund Name NYLI MacKay High Yield Corporate Bond Fund
Class Name SIMPLE Class
Trading Symbol MHHSX
Annual or Semi-Annual Statement [Text Block] This semiannual shareholder report contains important information about NYLI MacKay High Yield Corporate Bond Fund (the "Fund") for the period November 1, 2024 to April 30, 2025.
Shareholder Report Annual or Semi-Annual semi-annual shareholder report
Additional Information [Text Block] You can find additional information about the Fund at dfinview.com/NYLIM. You can also request this information by contacting us at 800-624-6782.
Additional Information Phone Number 800-624-6782
Additional Information Website dfinview.com/NYLIM
Expenses [Text Block]
What were the Fund costs for the last six months?
(Based on a hypothetical $10,000 investment)
Share Class Name Costs of a $10,000 investment Costs paid as a percentage
of a $10,000 investment1
SIMPLE Class $59 1.18%
1.
Annualized.
Expenses Paid, Amount $ 59
Expense Ratio, Percent 1.18% [25]
Performance Past Does Not Indicate Future [Text] Keep in mind that the Fund ’s past performance is not a good predictor of how the Fund will perform in the future.
Line Graph [Table Text Block]
Fund Performance
The following graph compares the initial and subsequent account values at the end of each of the most recently completed 10 semiannual reporting periods of the Fund (or for the life of the Fund, if shorter). It assumes a $10,000 initial investment at the beginning of the first fiscal period in an appropriate, broad-based securities market index and other additional indexes, if applicable, for the same period and reflects the deduction of all sales charges, where applicable.
Fund Performance - Growth of 10K
Average Annual Return [Table Text Block]
Average Annual Total Returns for the Period Ended April 30, 2025 Inception
Date		 Six
Months1		 One
Year		 Since
Inception
SIMPLE Class Shares 8/31/2020 1.07% 5.85% 3.71%
Bloomberg U.S. Aggregate Bond Index2 2.57% 8.02% (1.09)%
ICE BofA U.S. High Yield Constrained Index3 1.67% 8.69% 4.38%
Morningstar High Yield Bond Category Average4 1.47% 7.52% 3.88%
1.
Not annualized.
2.
The Fund has selected the Bloomberg U.S. Aggregate Bond Index to represent a broad measure of market performance. The Bloomberg U.S. Aggregate Bond Index is a broad-based benchmark that measures the performance of the investment grade, U.S. dollar-denominated, fixed-rate taxable bond market, including Treasuries, government-related and corporate securities, mortgage-backed securities (agency fixed-rate and hybrid adjustable rate mortgage pass-throughs), asset-backed securities and commercial mortgage-backed securities.
3.
The ICE BofA U.S. High Yield Constrained Index, which is generally representative of the market sectors or types of investments in which the Fund invests, is a market value-weighted index of all domestic and Yankee high-yield bonds, including deferred interest bonds and payment-in-kind securities. Issuers included in the ICE BofA U.S. High Yield Constrained Index have maturities of one year or more and have a credit rating lower than BBB-/Baa3, but are not in default. No single issuer may constitute greater than 2% of the ICE BofA U.S. High Yield Constrained Index.
4.
The Morningstar High Yield Bond Category Average is representative of funds that concentrate on lower-quality bonds, which are riskier than those of higher-quality companies. These funds primarily invest in U.S. high-income debt securities where at least 65% or more of bond assets are not rated or are rated by a major agency such as Standard & Poor’s or Moody’s at the level of BB and below. Results are based on average total returns of similar funds with all dividends and capital gain distributions reinvested.
Performance Inception Date Aug. 31, 2020
No Deduction of Taxes [Text Block] The graph and table do not reflect the deduction of taxes that a shareholder would pay on Fund distributions or redemption of Fund shares.
Updated Performance Information Location [Text Block] Visit newyorklifeinvestments.com/funds for the most recent performance information.
Net Assets $ 11,114,470,812
Holdings Count | Holding 633
Investment Company Portfolio Turnover 15.00%
Additional Fund Statistics [Text Block]
Key Fund Statistics
Fund's net assets $11,114,470,812%
Total number of portfolio holdings 633%
Portfolio turnover rate 15%
Holdings [Text Block]
Graphical Representation of Holdings
The tables below show the investment makeup of the Fund; percentages indicated are based on the Fund's net assets.
Top Ten Holdings and/or Issuers*
TransDigm, Inc., 4.625%-7.125%, due 11/15/27-1/15/33 2.3%
CCO Holdings LLC, 4.25%-5.375%, due 5/1/27-1/15/34 2.1%
Yum! Brands, Inc., 3.625%-5.375%, due 1/15/30-4/1/32 1.2%
Churchill Downs, Inc., 4.75%-6.75%, due 4/1/27-5/1/31 1.2%
Hilton Domestic Operating Co., Inc., 4.00%-5.875%, due 5/1/28-3/15/33 1.1%
Jane Street Group, 6.125%-7.125%, due 4/30/31-5/1/33 1.0%
LifePoint Health, Inc., 5.375%-11.00%, due 1/15/29-6/1/32 1.0%
Mineral Resources Ltd., 8.00%-9.25%, due 5/1/27-5/1/30 1.0%
1011778 B.C. Unlimited Liability Co., 3.875%-6.125%, due 1/15/28-10/15/30 0.9%
Great Outdoors Group LLC, 7.572%, due 1/23/32 0.9%
* Excluding short-term investments
Portfolio Composition 
Corporate Bonds 85.2%
Loan Assignments 7.7%
Common Stocks 0.6%
Convertible Bonds 0.5%
Exchange-Traded Funds 0.4%
Preferred Stocks 0.3%
Other Assets, Less Liabilities 5.3%
Largest Holdings [Text Block]
Top Ten Holdings and/or Issuers*
TransDigm, Inc., 4.625%-7.125%, due 11/15/27-1/15/33 2.3%
CCO Holdings LLC, 4.25%-5.375%, due 5/1/27-1/15/34 2.1%
Yum! Brands, Inc., 3.625%-5.375%, due 1/15/30-4/1/32 1.2%
Churchill Downs, Inc., 4.75%-6.75%, due 4/1/27-5/1/31 1.2%
Hilton Domestic Operating Co., Inc., 4.00%-5.875%, due 5/1/28-3/15/33 1.1%
Jane Street Group, 6.125%-7.125%, due 4/30/31-5/1/33 1.0%
LifePoint Health, Inc., 5.375%-11.00%, due 1/15/29-6/1/32 1.0%
Mineral Resources Ltd., 8.00%-9.25%, due 5/1/27-5/1/30 1.0%
1011778 B.C. Unlimited Liability Co., 3.875%-6.125%, due 1/15/28-10/15/30 0.9%
Great Outdoors Group LLC, 7.572%, due 1/23/32 0.9%
* Excluding short-term investments
C000018697 [Member]  
Shareholder Report [Line Items]  
Fund Name NYLI Money Market Fund
Class Name Class A
Trading Symbol MMAXX
Annual or Semi-Annual Statement [Text Block] This semiannual shareholder report contains important information about NYLI Money Market Fund (the "Fund") for the period November 1, 2024 to April 30, 2025.
Shareholder Report Annual or Semi-Annual semi-annual shareholder report
Additional Information [Text Block] You can find additional information about the Fund at dfinview.com/NYLIM. You can also request this information by contacting us at 800-624-6782.
Additional Information Phone Number 800-624-6782
Additional Information Website dfinview.com/NYLIM
Expenses [Text Block]
What were the Fund costs for the last six months?
(Based on a hypothetical $10,000 investment)
Share Class Name Costs of a $10,000 investment Costs paid as a percentage
of a $10,000 investment1
Class A $26 0.51%
1.
Annualized.
Expenses Paid, Amount $ 26
Expense Ratio, Percent 0.51% [26]
Performance Past Does Not Indicate Future [Text] Keep in mind that the Fund ’s past performance is not a good predictor of how the Fund will perform in the future.
Line Graph [Table Text Block]
Fund Performance
The following graph compares the initial and subsequent account values at the end of each of the most recently completed 10 semiannual reporting periods of the Fund (or for the life of the Fund, if shorter). It assumes a $15,000 initial investment at the beginning of the first fiscal period in an equally weighted performance average of money market funds and other additional indexes, if applicable, for the same period and reflects the deduction of all sales charges, where applicable.
Fund Performance - Growth of 10K
Average Annual Return [Table Text Block]
Average Annual Total Returns for the Period Ended April 30, 2025 Inception
Date		 Six
Months1		 One
Year		 Five
Years		 Ten
Years
Class A Shares 1/3/1995 2.00% 4.49% 2.41% 1.59%
Average Lipper Money Market Fund2 2.05% 4.57% 2.48% 1.70%
1.
Not annualized.
2.
The Average Lipper Money Market Fund is an equally weighted performance average adjusted for capital gains distributions and income dividends of all of the money market funds in the Lipper Universe. Lipper Inc., a wholly-owned subsidiary of Reuters Group PLC, is an independent monitor of mutual fund performance. Lipper averages are not class specific. Lipper returns are unaudited. Results are based on average total returns of similar funds with all dividend and capital gain distributions reinvested.
Performance Inception Date Jan. 03, 1995
No Deduction of Taxes [Text Block] The graph and table do not reflect the deduction of taxes that a shareholder would pay on Fund distributions or redemption of Fund shares.
Updated Performance Information Location [Text Block] Visit newyorklifeinvestments.com/funds for the most recent performance information.
Net Assets $ 575,375,870
Holdings Count | Holding 23
Additional Fund Statistics [Text Block]
Key Fund Statistics
Fund's net assets $575,375,870
Total number of portfolio holdings 23
Holdings [Text Block]
Graphical Representation of Holdings
The tables below show the investment makeup of the Fund; percentages indicated are based on the Fund's net assets.
Portfolio Composition 
Commercial Paper 43.7%
Repurchase Agreements 32.2%
U.S. Treasury Debt 24.1%
Other Assets, Less Liabilities 0.0%‡
‡
Less than one-tenth of a percent.
C000018699 [Member]  
Shareholder Report [Line Items]  
Fund Name NYLI Money Market Fund
Class Name Class C
Trading Symbol MSCXX
Annual or Semi-Annual Statement [Text Block] This semiannual shareholder report contains important information about NYLI Money Market Fund (the "Fund") for the period November 1, 2024 to April 30, 2025.
Shareholder Report Annual or Semi-Annual semi-annual shareholder report
Additional Information [Text Block] You can find additional information about the Fund at dfinview.com/NYLIM. You can also request this information by contacting us at 800-624-6782.
Additional Information Phone Number 800-624-6782
Additional Information Website dfinview.com/NYLIM
Expenses [Text Block]
What were the Fund costs for the last six months?
(Based on a hypothetical $10,000 investment)
Share Class Name Costs of a $10,000 investment Costs paid as a percentage
of a $10,000 investment1,2
Class C $40 0.79%
1.
Reflects fee waivers and/or expense reimbursements, without which expenses would have been higher.
2.
Annualized.
Expenses Paid, Amount $ 40
Expense Ratio, Percent 0.79% [27],[28]
Performance Past Does Not Indicate Future [Text] Keep in mind that the Fund ’s past performance is not a good predictor of how the Fund will perform in the future.
Line Graph [Table Text Block]
Fund Performance
The following graph compares the initial and subsequent account values at the end of each of the most recently completed 10 semiannual reporting periods of the Fund (or for the life of the Fund, if shorter). It assumes a $10,000 initial investment at the beginning of the first fiscal period in an equally weighted performance average of money market funds and other additional indexes, if applicable, for the same period and reflects the deduction of all sales charges, where applicable.
Fund Performance - Growth of 10K
Average Annual Return [Table Text Block]
Average Annual Total Returns for the Period Ended April 30, 2025 Inception
Date		 Six
Months1		 One
Year		 Five
Years		 Ten
Years
Class C Shares 9/1/1998 1.86% 4.20% 2.24% 1.43%
Average Lipper Money Market Fund2 2.05% 4.57% 2.48% 1.70%
1.
Not annualized.
2.
The Average Lipper Money Market Fund is an equally weighted performance average adjusted for capital gains distributions and income dividends of all of the money market funds in the Lipper Universe. Lipper Inc., a wholly-owned subsidiary of Reuters Group PLC, is an independent monitor of mutual fund performance. Lipper averages are not class specific. Lipper returns are unaudited. Results are based on average total returns of similar funds with all dividend and capital gain distributions reinvested.
Performance Inception Date Sep. 01, 1998
No Deduction of Taxes [Text Block] The graph and table do not reflect the deduction of taxes that a shareholder would pay on Fund distributions or redemption of Fund shares.
Updated Performance Information Location [Text Block] Visit newyorklifeinvestments.com/funds for the most recent performance information.
Net Assets $ 575,375,870
Holdings Count | Holding 23
Additional Fund Statistics [Text Block]
Key Fund Statistics
Fund's net assets $575,375,870
Total number of portfolio holdings 23
Holdings [Text Block]
Graphical Representation of Holdings
The tables below show the investment makeup of the Fund; percentages indicated are based on the Fund's net assets.
Portfolio Composition 
Commercial Paper 43.7%
Repurchase Agreements 32.2%
U.S. Treasury Debt 24.1%
Other Assets, Less Liabilities 0.0%‡
‡
Less than one-tenth of a percent.
C000060793 [Member]  
Shareholder Report [Line Items]  
Fund Name NYLI Money Market Fund
Class Name Investor Class
Trading Symbol MKTXX
Annual or Semi-Annual Statement [Text Block] This semiannual shareholder report contains important information about NYLI Money Market Fund (the "Fund") for the period November 1, 2024 to April 30, 2025.
Shareholder Report Annual or Semi-Annual semi-annual shareholder report
Additional Information [Text Block] You can find additional information about the Fund at dfinview.com/NYLIM. You can also request this information by contacting us at 800-624-6782.
Additional Information Phone Number 800-624-6782
Additional Information Website dfinview.com/NYLIM
Expenses [Text Block]
What were the Fund costs for the last six months?
(Based on a hypothetical $10,000 investment)
Share Class Name Costs of a $10,000 investment Costs paid as a percentage
of a $10,000 investment1,2
Investor Class $40 0.79%
1.
Reflects fee waivers and/or expense reimbursements, without which expenses would have been higher.
2.
Annualized.
Expenses Paid, Amount $ 40
Expense Ratio, Percent 0.79% [29],[30]
Performance Past Does Not Indicate Future [Text] Keep in mind that the Fund ’s past performance is not a good predictor of how the Fund will perform in the future.
Line Graph [Table Text Block]
Fund Performance
The following graph compares the initial and subsequent account values at the end of each of the most recently completed 10 semiannual reporting periods of the Fund (or for the life of the Fund, if shorter). It assumes a $10,000 initial investment at the beginning of the first fiscal period in an equally weighted performance average of money market funds and other additional indexes, if applicable, for the same period and reflects the deduction of all sales charges, where applicable.
Fund Performance - Growth of 10K
Average Annual Return [Table Text Block]
Average Annual Total Returns for the Period Ended April 30, 2025 Inception
Date		 Six
Months1		 One
Year		 Five
Years		 Ten
Years
Investor Class Shares 2/28/2008 1.86% 4.20% 2.24% 1.43%
Average Lipper Money Market Fund2 2.05% 4.57% 2.48% 1.70%
1.
Not annualized.
2.
The Average Lipper Money Market Fund is an equally weighted performance average adjusted for capital gains distributions and income dividends of all of the money market funds in the Lipper Universe. Lipper Inc., a wholly-owned subsidiary of Reuters Group PLC, is an independent monitor of mutual fund performance. Lipper averages are not class specific. Lipper returns are unaudited. Results are based on average total returns of similar funds with all dividend and capital gain distributions reinvested.
Performance Inception Date Feb. 28, 2008
No Deduction of Taxes [Text Block] The graph and table do not reflect the deduction of taxes that a shareholder would pay on Fund distributions or redemption of Fund shares.
Updated Performance Information Location [Text Block] Visit newyorklifeinvestments.com/funds for the most recent performance information.
Net Assets $ 575,375,870
Holdings Count | Holding 23
Additional Fund Statistics [Text Block]
Key Fund Statistics
Fund's net assets $575,375,870
Total number of portfolio holdings 23
Holdings [Text Block]
Graphical Representation of Holdings
The tables below show the investment makeup of the Fund; percentages indicated are based on the Fund's net assets.
Portfolio Composition 
Commercial Paper 43.7%
Repurchase Agreements 32.2%
U.S. Treasury Debt 24.1%
Other Assets, Less Liabilities 0.0%‡
‡
Less than one-tenth of a percent.
C000221692 [Member]  
Shareholder Report [Line Items]  
Fund Name NYLI Money Market Fund
Class Name SIMPLE Class
Trading Symbol MIPXX
Annual or Semi-Annual Statement [Text Block] This semiannual shareholder report contains important information about NYLI Money Market Fund (the "Fund") for the period November 1, 2024 to April 30, 2025.
Shareholder Report Annual or Semi-Annual semi-annual shareholder report
Additional Information [Text Block] You can find additional information about the Fund at dfinview.com/NYLIM. You can also request this information by contacting us at 800-624-6782.
Additional Information Phone Number 800-624-6782
Additional Information Website dfinview.com/NYLIM
Expenses [Text Block]
What were the Fund costs for the last six months?
(Based on a hypothetical $10,000 investment)
Share Class Name Costs of a $10,000 investment Costs paid as a percentage
of a $10,000 investment1
SIMPLE Class $25 0.49%
1.
Annualized.
Expenses Paid, Amount $ 25
Expense Ratio, Percent 0.49% [31]
Performance Past Does Not Indicate Future [Text] Keep in mind that the Fund ’s past performance is not a good predictor of how the Fund will perform in the future.
Line Graph [Table Text Block]
Fund Performance
The following graph compares the initial and subsequent account values at the end of each of the most recently completed 10 semiannual reporting periods of the Fund (or for the life of the Fund, if shorter). It assumes a $10,000 initial investment at the beginning of the first fiscal period in an equally weighted performance average of money market funds and other additional indexes, if applicable, for the same period and reflects the deduction of all sales charges, where applicable.
Fund Performance - Growth of 10K
Average Annual Return [Table Text Block]
Average Annual Total Returns for the Period Ended April 30, 2025 Inception
Date		 Six
Months1		 One
Year		 Since
Inception
SIMPLE Class Shares 8/31/2020 2.01% 4.53% 2.55%
Average Lipper Money Market Fund2 2.05% 4.57% 2.65%
1.
Not annualized.
2.
The Average Lipper Money Market Fund is an equally weighted performance average adjusted for capital gains distributions and income dividends of all of the money market funds in the Lipper Universe. Lipper Inc., a wholly-owned subsidiary of Reuters Group PLC, is an independent monitor of mutual fund performance. Lipper averages are not class specific. Lipper returns are unaudited. Results are based on average total returns of similar funds with all dividend and capital gain distributions reinvested.
Performance Inception Date Aug. 31, 2020
No Deduction of Taxes [Text Block] The graph and table do not reflect the deduction of taxes that a shareholder would pay on Fund distributions or redemption of Fund shares.
Updated Performance Information Location [Text Block] Visit newyorklifeinvestments.com/funds for the most recent performance information.
Net Assets $ 575,375,870
Holdings Count | Holding 23
Additional Fund Statistics [Text Block]
Key Fund Statistics
Fund's net assets $575,375,870
Total number of portfolio holdings 23
Holdings [Text Block]
Graphical Representation of Holdings
The tables below show the investment makeup of the Fund; percentages indicated are based on the Fund's net assets.
Portfolio Composition 
Commercial Paper 43.7%
Repurchase Agreements 32.2%
U.S. Treasury Debt 24.1%
Other Assets, Less Liabilities 0.0%‡
‡
Less than one-tenth of a percent.
C000018700 [Member]  
Shareholder Report [Line Items]  
Fund Name NYLI MacKay Tax Free Bond Fund
Class Name Class A
Trading Symbol MTBAX
Annual or Semi-Annual Statement [Text Block] This semiannual shareholder report contains important information about NYLI MacKay Tax Free Bond Fund (the "Fund") for the period November 1, 2024 to April 30, 2025.
Shareholder Report Annual or Semi-Annual semi-annual shareholder report
Additional Information [Text Block] You can find additional information about the Fund at dfinview.com/NYLIM. You can also request this information by contacting us at 800-624-6782.
Additional Information Phone Number 800-624-6782
Additional Information Website dfinview.com/NYLIM
Expenses [Text Block]
What were the Fund costs for the last six months?
(Based on a hypothetical $10,000 investment)
Share Class Name Costs of a $10,000 investment Costs paid as a percentage
of a $10,000 investment1
Class A $36 0.73%
1.
Annualized.
Expenses Paid, Amount $ 36
Expense Ratio, Percent 0.73% [32]
Performance Past Does Not Indicate Future [Text] Keep in mind that the Fund ’s past performance is not a good predictor of how the Fund will perform in the future.
Line Graph [Table Text Block]
Fund Performance
The following graph compares the initial and subsequent account values at the end of each of the most recently completed 10 semiannual reporting periods of the Fund (or for the life of the Fund, if shorter). It assumes a $15,000 initial investment at the beginning of the first fiscal period in an appropriate, broad-based securities market index and other additional indexes, if applicable, for the same period and reflects the deduction of all sales charges, where applicable.
Fund Performance - Growth of 10K
Average Annual Return [Table Text Block]
Average Annual Total Returns for the Period Ended April 30, 2025 Inception
Date		 Six
Months1		 One
Year		 Five
Years		 Ten
Years
Class A Shares - Including sales charges 1/3/1995 (3.91)% (1.54)% 0.24% 1.68%
Class A Shares - Excluding sales charges (0.94)% 1.51% 1.17% 2.15%
Bloomberg Municipal Bond Index2 (0.78)% 1.66% 1.17% 2.10%
Morningstar Muni National Long Category Average3 (1.35)% 2.00% 1.43% 1.99%
1.
Not annualized.
2.
The Fund has selected the Bloomberg Municipal Bond Index to represent a broad measure of market performance. The Bloomberg Municipal Bond Index is considered representative of the broad market for investment-grade, tax-exempt bonds with a maturity of at least one year. Bonds subject to the alternative minimum tax or with floating or zero coupons are excluded.
3.
The Morningstar Muni National Long Category Average is representative of funds that invest in bonds issued by various state and local governments to fund public projects. The income from these bonds is generally free from federal taxes. These funds have durations of more than 7 years. Results are based on average total returns of similar funds with all dividends and capital gain distributions reinvested.
Performance Inception Date Jan. 03, 1995
No Deduction of Taxes [Text Block] The graph and table do not reflect the deduction of taxes that a shareholder would pay on Fund distributions or redemption of Fund shares.
Updated Performance Information Location [Text Block] Visit newyorklifeinvestments.com/funds for the most recent performance information.
Net Assets $ 8,898,665,906
Holdings Count | Holding 1,067
Investment Company Portfolio Turnover 37.00%
Additional Fund Statistics [Text Block]
Key Fund Statistics
Fund's net assets $8,898,665,906%
Total number of portfolio holdings 1,067%
Portfolio turnover rate 37%
Holdings [Text Block]
Graphical Representation of Holdings
The tables below show the investment makeup of the Fund; percentages indicated are based on the Fund's net assets.
Top Ten Holdings and/or Issuers*
Los Angeles Department of Water & Power, 3.65%-6.603%, due 7/1/28-7/1/55 3.5%
San Francisco City & County Airport Commission, 5.00%-5.50%, due 5/1/30-5/1/55 2.5%
New York City Transitional Finance Authority, 3.00%-5.50%, due 11/1/36-5/1/53 2.4%
California Community Choice Financing Authority, 4.00%-5.25%, due 2/1/52-11/1/55 2.2%
Black Belt Energy Gas District, 4.00%-5.50%, due 6/1/49-5/1/55 1.9%
New York State Dormitory Authority, 3.00%-5.75%, due 7/1/27-7/1/54 1.9%
Main Street Natural Gas, Inc., 4.00%-5.50%, due 9/15/27-5/1/55 1.5%
Triborough Bridge & Tunnel Authority, 3.00%-5.50%, due 3/15/27-5/15/63 1.5%
New Hampshire Business Finance Authority, 3.00%-6.89%, due 4/1/34-7/1/54 1.5%
Southeast Energy Authority A Cooperative District, 4.00%-5.25%, due 11/1/35-1/1/56 1.4%
* Excluding short-term investments
Top States
California 15.1%
New York 13.9%
Texas 9.9%
Illinois 6.7%
Florida 5.6%
Alabama 4.9%
Georgia 3.8%
Pennsylvania 2.6%
Colorado 2.5%
Utah 2.4%
Largest Holdings [Text Block]
Top Ten Holdings and/or Issuers*
Los Angeles Department of Water & Power, 3.65%-6.603%, due 7/1/28-7/1/55 3.5%
San Francisco City & County Airport Commission, 5.00%-5.50%, due 5/1/30-5/1/55 2.5%
New York City Transitional Finance Authority, 3.00%-5.50%, due 11/1/36-5/1/53 2.4%
California Community Choice Financing Authority, 4.00%-5.25%, due 2/1/52-11/1/55 2.2%
Black Belt Energy Gas District, 4.00%-5.50%, due 6/1/49-5/1/55 1.9%
New York State Dormitory Authority, 3.00%-5.75%, due 7/1/27-7/1/54 1.9%
Main Street Natural Gas, Inc., 4.00%-5.50%, due 9/15/27-5/1/55 1.5%
Triborough Bridge & Tunnel Authority, 3.00%-5.50%, due 3/15/27-5/15/63 1.5%
New Hampshire Business Finance Authority, 3.00%-6.89%, due 4/1/34-7/1/54 1.5%
Southeast Energy Authority A Cooperative District, 4.00%-5.25%, due 11/1/35-1/1/56 1.4%
* Excluding short-term investments
C000018702 [Member]  
Shareholder Report [Line Items]  
Fund Name NYLI MacKay Tax Free Bond Fund
Class Name Class C
Trading Symbol MTFCX
Annual or Semi-Annual Statement [Text Block] This semiannual shareholder report contains important information about NYLI MacKay Tax Free Bond Fund (the "Fund") for the period November 1, 2024 to April 30, 2025.
Shareholder Report Annual or Semi-Annual semi-annual shareholder report
Additional Information [Text Block] You can find additional information about the Fund at dfinview.com/NYLIM. You can also request this information by contacting us at 800-624-6782.
Additional Information Phone Number 800-624-6782
Additional Information Website dfinview.com/NYLIM
Expenses [Text Block]
What were the Fund costs for the last six months?
(Based on a hypothetical $10,000 investment)
Share Class Name Costs of a $10,000 investment Costs paid as a percentage
of a $10,000 investment1
Class C $51 1.03%
1.
Annualized.
Expenses Paid, Amount $ 51
Expense Ratio, Percent 1.03% [33]
Performance Past Does Not Indicate Future [Text] Keep in mind that the Fund ’s past performance is not a good predictor of how the Fund will perform in the future.
Line Graph [Table Text Block]
Fund Performance
The following graph compares the initial and subsequent account values at the end of each of the most recently completed 10 semiannual reporting periods of the Fund (or for the life of the Fund, if shorter). It assumes a $10,000 initial investment at the beginning of the first fiscal period in an appropriate, broad-based securities market index and other additional indexes, if applicable, for the same period and reflects the deduction of all sales charges, where applicable.
Fund Performance - Growth of 10K
Average Annual Return [Table Text Block]
Average Annual Total Returns for the Period Ended April 30, 2025 Inception
Date		 Six
Months1		 One
Year		 Five
Years		 Ten
Years
Class C Shares - Including sales charges 9/1/1998 (1.95)% 0.34% 0.91% 1.90%
Class C Shares - Excluding sales charges (0.97)% 1.32% 0.91% 1.90%
Bloomberg Municipal Bond Index2 (0.78)% 1.66% 1.17% 2.10%
Morningstar Muni National Long Category Average3 (1.35)% 2.00% 1.43% 1.99%
1.
Not annualized.
2.
The Fund has selected the Bloomberg Municipal Bond Index to represent a broad measure of market performance. The Bloomberg Municipal Bond Index is considered representative of the broad market for investment-grade, tax-exempt bonds with a maturity of at least one year. Bonds subject to the alternative minimum tax or with floating or zero coupons are excluded.
3.
The Morningstar Muni National Long Category Average is representative of funds that invest in bonds issued by various state and local governments to fund public projects. The income from these bonds is generally free from federal taxes. These funds have durations of more than 7 years. Results are based on average total returns of similar funds with all dividends and capital gain distributions reinvested.
Performance Inception Date Sep. 01, 1998
No Deduction of Taxes [Text Block] The graph and table do not reflect the deduction of taxes that a shareholder would pay on Fund distributions or redemption of Fund shares.
Updated Performance Information Location [Text Block] Visit newyorklifeinvestments.com/funds for the most recent performance information.
Net Assets $ 8,898,665,906
Holdings Count | Holding 1,067
Investment Company Portfolio Turnover 37.00%
Additional Fund Statistics [Text Block]
Key Fund Statistics
Fund's net assets $8,898,665,906%
Total number of portfolio holdings 1,067%
Portfolio turnover rate 37%
Holdings [Text Block]
Graphical Representation of Holdings
The tables below show the investment makeup of the Fund; percentages indicated are based on the Fund's net assets.
Top Ten Holdings and/or Issuers*
Los Angeles Department of Water & Power, 3.65%-6.603%, due 7/1/28-7/1/55 3.5%
San Francisco City & County Airport Commission, 5.00%-5.50%, due 5/1/30-5/1/55 2.5%
New York City Transitional Finance Authority, 3.00%-5.50%, due 11/1/36-5/1/53 2.4%
California Community Choice Financing Authority, 4.00%-5.25%, due 2/1/52-11/1/55 2.2%
Black Belt Energy Gas District, 4.00%-5.50%, due 6/1/49-5/1/55 1.9%
New York State Dormitory Authority, 3.00%-5.75%, due 7/1/27-7/1/54 1.9%
Main Street Natural Gas, Inc., 4.00%-5.50%, due 9/15/27-5/1/55 1.5%
Triborough Bridge & Tunnel Authority, 3.00%-5.50%, due 3/15/27-5/15/63 1.5%
New Hampshire Business Finance Authority, 3.00%-6.89%, due 4/1/34-7/1/54 1.5%
Southeast Energy Authority A Cooperative District, 4.00%-5.25%, due 11/1/35-1/1/56 1.4%
* Excluding short-term investments
Top States
California 15.1%
New York 13.9%
Texas 9.9%
Illinois 6.7%
Florida 5.6%
Alabama 4.9%
Georgia 3.8%
Pennsylvania 2.6%
Colorado 2.5%
Utah 2.4%
Largest Holdings [Text Block]
Top Ten Holdings and/or Issuers*
Los Angeles Department of Water & Power, 3.65%-6.603%, due 7/1/28-7/1/55 3.5%
San Francisco City & County Airport Commission, 5.00%-5.50%, due 5/1/30-5/1/55 2.5%
New York City Transitional Finance Authority, 3.00%-5.50%, due 11/1/36-5/1/53 2.4%
California Community Choice Financing Authority, 4.00%-5.25%, due 2/1/52-11/1/55 2.2%
Black Belt Energy Gas District, 4.00%-5.50%, due 6/1/49-5/1/55 1.9%
New York State Dormitory Authority, 3.00%-5.75%, due 7/1/27-7/1/54 1.9%
Main Street Natural Gas, Inc., 4.00%-5.50%, due 9/15/27-5/1/55 1.5%
Triborough Bridge & Tunnel Authority, 3.00%-5.50%, due 3/15/27-5/15/63 1.5%
New Hampshire Business Finance Authority, 3.00%-6.89%, due 4/1/34-7/1/54 1.5%
Southeast Energy Authority A Cooperative District, 4.00%-5.25%, due 11/1/35-1/1/56 1.4%
* Excluding short-term investments
C000221693 [Member]  
Shareholder Report [Line Items]  
Fund Name NYLI MacKay Tax Free Bond Fund
Class Name Class C2
Trading Symbol MTSPX
Annual or Semi-Annual Statement [Text Block] This semiannual shareholder report contains important information about NYLI MacKay Tax Free Bond Fund (the "Fund") for the period November 1, 2024 to April 30, 2025.
Shareholder Report Annual or Semi-Annual semi-annual shareholder report
Additional Information [Text Block] You can find additional information about the Fund at dfinview.com/NYLIM. You can also request this information by contacting us at 800-624-6782.
Additional Information Phone Number 800-624-6782
Additional Information Website dfinview.com/NYLIM
Expenses [Text Block]
What were the Fund costs for the last six months?
(Based on a hypothetical $10,000 investment)
Share Class Name Costs of a $10,000 investment Costs paid as a percentage
of a $10,000 investment1
Class C2 $58 1.18%
1.
Annualized.
Expenses Paid, Amount $ 58
Expense Ratio, Percent 1.18% [34]
Performance Past Does Not Indicate Future [Text] Keep in mind that the Fund ’s past performance is not a good predictor of how the Fund will perform in the future.
Line Graph [Table Text Block]
Fund Performance
The following graph compares the initial and subsequent account values at the end of each of the most recently completed 10 semiannual reporting periods of the Fund (or for the life of the Fund, if shorter). It assumes a $10,000 initial investment at the beginning of the first fiscal period in an appropriate, broad-based securities market index and other additional indexes, if applicable, for the same period and reflects the deduction of all sales charges, where applicable.
Fund Performance - Growth of 10K
Average Annual Return [Table Text Block]
Average Annual Total Returns for the Period Ended April 30, 2025 Inception
Date		 Six
Months1		 One
Year		 Since
Inception
Class C2 Shares - Including sales charges 8/31/2020 (2.13)% 0.19% (0.48)%
Class C2 Shares - Excluding sales charges (1.15)% 1.17% (0.48)%
Bloomberg Municipal Bond Index2 (0.78)% 1.66% 0.14%
Morningstar Muni National Long Category Average3 (1.35)% 2.00% (0.01)%
1.
Not annualized.
2.
The Fund has selected the Bloomberg Municipal Bond Index to represent a broad measure of market performance. The Bloomberg Municipal Bond Index is considered representative of the broad market for investment-grade, tax-exempt bonds with a maturity of at least one year. Bonds subject to the alternative minimum tax or with floating or zero coupons are excluded.
3.
The Morningstar Muni National Long Category Average is representative of funds that invest in bonds issued by various state and local governments to fund public projects. The income from these bonds is generally free from federal taxes. These funds have durations of more than 7 years. Results are based on average total returns of similar funds with all dividends and capital gain distributions reinvested.
Performance Inception Date Aug. 31, 2020
No Deduction of Taxes [Text Block] The graph and table do not reflect the deduction of taxes that a shareholder would pay on Fund distributions or redemption of Fund shares.
Updated Performance Information Location [Text Block] Visit newyorklifeinvestments.com/funds for the most recent performance information.
Net Assets $ 8,898,665,906
Holdings Count | Holding 1,067
Investment Company Portfolio Turnover 37.00%
Additional Fund Statistics [Text Block]
Key Fund Statistics
Fund's net assets $8,898,665,906%
Total number of portfolio holdings 1,067%
Portfolio turnover rate 37%
Holdings [Text Block]
Graphical Representation of Holdings
The tables below show the investment makeup of the Fund; percentages indicated are based on the Fund's net assets.
Top Ten Holdings and/or Issuers*
Los Angeles Department of Water & Power, 3.65%-6.603%, due 7/1/28-7/1/55 3.5%
San Francisco City & County Airport Commission, 5.00%-5.50%, due 5/1/30-5/1/55 2.5%
New York City Transitional Finance Authority, 3.00%-5.50%, due 11/1/36-5/1/53 2.4%
California Community Choice Financing Authority, 4.00%-5.25%, due 2/1/52-11/1/55 2.2%
Black Belt Energy Gas District, 4.00%-5.50%, due 6/1/49-5/1/55 1.9%
New York State Dormitory Authority, 3.00%-5.75%, due 7/1/27-7/1/54 1.9%
Main Street Natural Gas, Inc., 4.00%-5.50%, due 9/15/27-5/1/55 1.5%
Triborough Bridge & Tunnel Authority, 3.00%-5.50%, due 3/15/27-5/15/63 1.5%
New Hampshire Business Finance Authority, 3.00%-6.89%, due 4/1/34-7/1/54 1.5%
Southeast Energy Authority A Cooperative District, 4.00%-5.25%, due 11/1/35-1/1/56 1.4%
* Excluding short-term investments
Top States
California 15.1%
New York 13.9%
Texas 9.9%
Illinois 6.7%
Florida 5.6%
Alabama 4.9%
Georgia 3.8%
Pennsylvania 2.6%
Colorado 2.5%
Utah 2.4%
Largest Holdings [Text Block]
Top Ten Holdings and/or Issuers*
Los Angeles Department of Water & Power, 3.65%-6.603%, due 7/1/28-7/1/55 3.5%
San Francisco City & County Airport Commission, 5.00%-5.50%, due 5/1/30-5/1/55 2.5%
New York City Transitional Finance Authority, 3.00%-5.50%, due 11/1/36-5/1/53 2.4%
California Community Choice Financing Authority, 4.00%-5.25%, due 2/1/52-11/1/55 2.2%
Black Belt Energy Gas District, 4.00%-5.50%, due 6/1/49-5/1/55 1.9%
New York State Dormitory Authority, 3.00%-5.75%, due 7/1/27-7/1/54 1.9%
Main Street Natural Gas, Inc., 4.00%-5.50%, due 9/15/27-5/1/55 1.5%
Triborough Bridge & Tunnel Authority, 3.00%-5.50%, due 3/15/27-5/15/63 1.5%
New Hampshire Business Finance Authority, 3.00%-6.89%, due 4/1/34-7/1/54 1.5%
Southeast Energy Authority A Cooperative District, 4.00%-5.25%, due 11/1/35-1/1/56 1.4%
* Excluding short-term investments
C000082082 [Member]  
Shareholder Report [Line Items]  
Fund Name NYLI MacKay Tax Free Bond Fund
Class Name Class I
Trading Symbol MTBIX
Annual or Semi-Annual Statement [Text Block] This semiannual shareholder report contains important information about NYLI MacKay Tax Free Bond Fund (the "Fund") for the period November 1, 2024 to April 30, 2025.
Shareholder Report Annual or Semi-Annual semi-annual shareholder report
Additional Information [Text Block] You can find additional information about the Fund at dfinview.com/NYLIM. You can also request this information by contacting us at 800-624-6782.
Additional Information Phone Number 800-624-6782
Additional Information Website dfinview.com/NYLIM
Expenses [Text Block]
What were the Fund costs for the last six months?
(Based on a hypothetical $10,000 investment)
Share Class Name Costs of a $10,000 investment Costs paid as a percentage
of a $10,000 investment1
Class I $24 0.48%
1.
Annualized.
Expenses Paid, Amount $ 24
Expense Ratio, Percent 0.48% [35]
Performance Past Does Not Indicate Future [Text] Keep in mind that the Fund ’s past performance is not a good predictor of how the Fund will perform in the future.
Line Graph [Table Text Block]
Fund Performance
The following graph compares the initial and subsequent account values at the end of each of the most recently completed 10 semiannual reporting periods of the Fund (or for the life of the Fund, if shorter). It assumes a $10,000 initial investment at the beginning of the first fiscal period in an appropriate, broad-based securities market index and other additional indexes, if applicable, for the same period and reflects the deduction of all sales charges, where applicable.
Fund Performance - Growth of 10K
Average Annual Return [Table Text Block]
Average Annual Total Returns for the Period Ended April 30, 2025 Inception
Date		 Six
Months1		 One
Year		 Five
Years		 Ten
Years
Class I Shares 12/21/2009 (0.70)% 1.87% 1.45% 2.41%
Bloomberg Municipal Bond Index2 (0.78)% 1.66% 1.17% 2.10%
Morningstar Muni National Long Category Average3 (1.35)% 2.00% 1.43% 1.99%
1.
Not annualized.
2.
The Fund has selected the Bloomberg Municipal Bond Index to represent a broad measure of market performance. The Bloomberg Municipal Bond Index is considered representative of the broad market for investment-grade, tax-exempt bonds with a maturity of at least one year. Bonds subject to the alternative minimum tax or with floating or zero coupons are excluded.
3.
The Morningstar Muni National Long Category Average is representative of funds that invest in bonds issued by various state and local governments to fund public projects. The income from these bonds is generally free from federal taxes. These funds have durations of more than 7 years. Results are based on average total returns of similar funds with all dividends and capital gain distributions reinvested.
Performance Inception Date Dec. 21, 2009
No Deduction of Taxes [Text Block] The graph and table do not reflect the deduction of taxes that a shareholder would pay on Fund distributions or redemption of Fund shares.
Updated Performance Information Location [Text Block] Visit newyorklifeinvestments.com/funds for the most recent performance information.
Net Assets $ 8,898,665,906
Holdings Count | Holding 1,067
Investment Company Portfolio Turnover 37.00%
Additional Fund Statistics [Text Block]
Key Fund Statistics
Fund's net assets $8,898,665,906%
Total number of portfolio holdings 1,067%
Portfolio turnover rate 37%
Holdings [Text Block]
Graphical Representation of Holdings
The tables below show the investment makeup of the Fund; percentages indicated are based on the Fund's net assets.
Top Ten Holdings and/or Issuers*
Los Angeles Department of Water & Power, 3.65%-6.603%, due 7/1/28-7/1/55 3.5%
San Francisco City & County Airport Commission, 5.00%-5.50%, due 5/1/30-5/1/55 2.5%
New York City Transitional Finance Authority, 3.00%-5.50%, due 11/1/36-5/1/53 2.4%
California Community Choice Financing Authority, 4.00%-5.25%, due 2/1/52-11/1/55 2.2%
Black Belt Energy Gas District, 4.00%-5.50%, due 6/1/49-5/1/55 1.9%
New York State Dormitory Authority, 3.00%-5.75%, due 7/1/27-7/1/54 1.9%
Main Street Natural Gas, Inc., 4.00%-5.50%, due 9/15/27-5/1/55 1.5%
Triborough Bridge & Tunnel Authority, 3.00%-5.50%, due 3/15/27-5/15/63 1.5%
New Hampshire Business Finance Authority, 3.00%-6.89%, due 4/1/34-7/1/54 1.5%
Southeast Energy Authority A Cooperative District, 4.00%-5.25%, due 11/1/35-1/1/56 1.4%
* Excluding short-term investments
Top States
California 15.1%
New York 13.9%
Texas 9.9%
Illinois 6.7%
Florida 5.6%
Alabama 4.9%
Georgia 3.8%
Pennsylvania 2.6%
Colorado 2.5%
Utah 2.4%
Largest Holdings [Text Block]
Top Ten Holdings and/or Issuers*
Los Angeles Department of Water & Power, 3.65%-6.603%, due 7/1/28-7/1/55 3.5%
San Francisco City & County Airport Commission, 5.00%-5.50%, due 5/1/30-5/1/55 2.5%
New York City Transitional Finance Authority, 3.00%-5.50%, due 11/1/36-5/1/53 2.4%
California Community Choice Financing Authority, 4.00%-5.25%, due 2/1/52-11/1/55 2.2%
Black Belt Energy Gas District, 4.00%-5.50%, due 6/1/49-5/1/55 1.9%
New York State Dormitory Authority, 3.00%-5.75%, due 7/1/27-7/1/54 1.9%
Main Street Natural Gas, Inc., 4.00%-5.50%, due 9/15/27-5/1/55 1.5%
Triborough Bridge & Tunnel Authority, 3.00%-5.50%, due 3/15/27-5/15/63 1.5%
New Hampshire Business Finance Authority, 3.00%-6.89%, due 4/1/34-7/1/54 1.5%
Southeast Energy Authority A Cooperative District, 4.00%-5.25%, due 11/1/35-1/1/56 1.4%
* Excluding short-term investments
C000185560 [Member]  
Shareholder Report [Line Items]  
Fund Name NYLI MacKay Tax Free Bond Fund
Class Name Class R6
Trading Symbol MTBDX
Annual or Semi-Annual Statement [Text Block] This semiannual shareholder report contains important information about NYLI MacKay Tax Free Bond Fund (the "Fund") for the period November 1, 2024 to April 30, 2025.
Shareholder Report Annual or Semi-Annual semi-annual shareholder report
Additional Information [Text Block] You can find additional information about the Fund at dfinview.com/NYLIM. You can also request this information by contacting us at 800-624-6782.
Additional Information Phone Number 800-624-6782
Additional Information Website dfinview.com/NYLIM
Expenses [Text Block]
What were the Fund costs for the last six months?
(Based on a hypothetical $10,000 investment)
Share Class Name Costs of a $10,000 investment Costs paid as a percentage
of a $10,000 investment1
Class R6 $21 0.43%
1.
Annualized.
Expenses Paid, Amount $ 21
Expense Ratio, Percent 0.43% [36]
Performance Past Does Not Indicate Future [Text] Keep in mind that the Fund ’s past performance is not a good predictor of how the Fund will perform in the future.
Line Graph [Table Text Block]
Fund Performance
The following graph compares the initial and subsequent account values at the end of each of the most recently completed 10 semiannual reporting periods of the Fund (or for the life of the Fund, if shorter). It assumes a $10,000 initial investment at the beginning of the first fiscal period in an appropriate, broad-based securities market index and other additional indexes, if applicable, for the same period and reflects the deduction of all sales charges, where applicable.
Fund Performance - Growth of 10K
Average Annual Return [Table Text Block]
Average Annual Total Returns for the Period Ended April 30, 2025 Inception
Date		 Six
Months1		 One
Year		 Five
Years		 Since
Inception
Class R6 Shares 11/1/2019 (0.79)% 1.92% 1.48% 1.00%
Bloomberg Municipal Bond Index2 (0.78)% 1.66% 1.17% 0.81%
Morningstar Muni National Long Category Average3 (1.35)% 2.00% 1.43% 0.52%
1.
Not annualized.
2.
The Fund has selected the Bloomberg Municipal Bond Index to represent a broad measure of market performance. The Bloomberg Municipal Bond Index is considered representative of the broad market for investment-grade, tax-exempt bonds with a maturity of at least one year. Bonds subject to the alternative minimum tax or with floating or zero coupons are excluded.
3.
The Morningstar Muni National Long Category Average is representative of funds that invest in bonds issued by various state and local governments to fund public projects. The income from these bonds is generally free from federal taxes. These funds have durations of more than 7 years. Results are based on average total returns of similar funds with all dividends and capital gain distributions reinvested.
Performance Inception Date Nov. 01, 2019
No Deduction of Taxes [Text Block] The graph and table do not reflect the deduction of taxes that a shareholder would pay on Fund distributions or redemption of Fund shares.
Updated Performance Information Location [Text Block] Visit newyorklifeinvestments.com/funds for the most recent performance information.
Net Assets $ 8,898,665,906
Holdings Count | Holding 1,067
Investment Company Portfolio Turnover 37.00%
Additional Fund Statistics [Text Block]
Key Fund Statistics
Fund's net assets $8,898,665,906%
Total number of portfolio holdings 1,067%
Portfolio turnover rate 37%
Holdings [Text Block]
Graphical Representation of Holdings
The tables below show the investment makeup of the Fund; percentages indicated are based on the Fund's net assets.
Top Ten Holdings and/or Issuers*
Los Angeles Department of Water & Power, 3.65%-6.603%, due 7/1/28-7/1/55 3.5%
San Francisco City & County Airport Commission, 5.00%-5.50%, due 5/1/30-5/1/55 2.5%
New York City Transitional Finance Authority, 3.00%-5.50%, due 11/1/36-5/1/53 2.4%
California Community Choice Financing Authority, 4.00%-5.25%, due 2/1/52-11/1/55 2.2%
Black Belt Energy Gas District, 4.00%-5.50%, due 6/1/49-5/1/55 1.9%
New York State Dormitory Authority, 3.00%-5.75%, due 7/1/27-7/1/54 1.9%
Main Street Natural Gas, Inc., 4.00%-5.50%, due 9/15/27-5/1/55 1.5%
Triborough Bridge & Tunnel Authority, 3.00%-5.50%, due 3/15/27-5/15/63 1.5%
New Hampshire Business Finance Authority, 3.00%-6.89%, due 4/1/34-7/1/54 1.5%
Southeast Energy Authority A Cooperative District, 4.00%-5.25%, due 11/1/35-1/1/56 1.4%
* Excluding short-term investments
Top States
California 15.1%
New York 13.9%
Texas 9.9%
Illinois 6.7%
Florida 5.6%
Alabama 4.9%
Georgia 3.8%
Pennsylvania 2.6%
Colorado 2.5%
Utah 2.4%
Largest Holdings [Text Block]
Top Ten Holdings and/or Issuers*
Los Angeles Department of Water & Power, 3.65%-6.603%, due 7/1/28-7/1/55 3.5%
San Francisco City & County Airport Commission, 5.00%-5.50%, due 5/1/30-5/1/55 2.5%
New York City Transitional Finance Authority, 3.00%-5.50%, due 11/1/36-5/1/53 2.4%
California Community Choice Financing Authority, 4.00%-5.25%, due 2/1/52-11/1/55 2.2%
Black Belt Energy Gas District, 4.00%-5.50%, due 6/1/49-5/1/55 1.9%
New York State Dormitory Authority, 3.00%-5.75%, due 7/1/27-7/1/54 1.9%
Main Street Natural Gas, Inc., 4.00%-5.50%, due 9/15/27-5/1/55 1.5%
Triborough Bridge & Tunnel Authority, 3.00%-5.50%, due 3/15/27-5/15/63 1.5%
New Hampshire Business Finance Authority, 3.00%-6.89%, due 4/1/34-7/1/54 1.5%
Southeast Energy Authority A Cooperative District, 4.00%-5.25%, due 11/1/35-1/1/56 1.4%
* Excluding short-term investments
C000060794 [Member]  
Shareholder Report [Line Items]  
Fund Name NYLI MacKay Tax Free Bond Fund
Class Name Investor Class
Trading Symbol MKINX
Annual or Semi-Annual Statement [Text Block] This semiannual shareholder report contains important information about NYLI MacKay Tax Free Bond Fund (the "Fund") for the period November 1, 2024 to April 30, 2025.
Shareholder Report Annual or Semi-Annual semi-annual shareholder report
Additional Information [Text Block] You can find additional information about the Fund at dfinview.com/NYLIM. You can also request this information by contacting us at 800-624-6782.
Additional Information Phone Number 800-624-6782
Additional Information Website dfinview.com/NYLIM
Expenses [Text Block]
What were the Fund costs for the last six months?
(Based on a hypothetical $10,000 investment)
Share Class Name Costs of a $10,000 investment Costs paid as a percentage
of a $10,000 investment1
Investor Class $38 0.78%
1.
Annualized.
Expenses Paid, Amount $ 38
Expense Ratio, Percent 0.78% [37]
Performance Past Does Not Indicate Future [Text] Keep in mind that the Fund ’s past performance is not a good predictor of how the Fund will perform in the future.
Line Graph [Table Text Block]
Fund Performance
The following graph compares the initial and subsequent account values at the end of each of the most recently completed 10 semiannual reporting periods of the Fund (or for the life of the Fund, if shorter). It assumes a $10,000 initial investment at the beginning of the first fiscal period in an appropriate, broad-based securities market index and other additional indexes, if applicable, for the same period and reflects the deduction of all sales charges, where applicable.
Fund Performance - Growth of 10K
Average Annual Return [Table Text Block]
Average Annual Total Returns for the Period Ended April 30, 2025 Inception
Date		 Six
Months1		 One
Year		 Five
Years		 Ten
Years
Investor Class Shares - Including sales charges 2/28/2008 (3.33)% (0.97)% 0.23% 1.68%
Investor Class Shares - Excluding sales charges (0.85)% 1.57% 1.16% 2.15%
Bloomberg Municipal Bond Index2 (0.78)% 1.66% 1.17% 2.10%
Morningstar Muni National Long Category Average3 (1.35)% 2.00% 1.43% 1.99%
1.
Not annualized.
2.
The Fund has selected the Bloomberg Municipal Bond Index to represent a broad measure of market performance. The Bloomberg Municipal Bond Index is considered representative of the broad market for investment-grade, tax-exempt bonds with a maturity of at least one year. Bonds subject to the alternative minimum tax or with floating or zero coupons are excluded.
3.
The Morningstar Muni National Long Category Average is representative of funds that invest in bonds issued by various state and local governments to fund public projects. The income from these bonds is generally free from federal taxes. These funds have durations of more than 7 years. Results are based on average total returns of similar funds with all dividends and capital gain distributions reinvested.
Performance Inception Date Feb. 28, 2008
No Deduction of Taxes [Text Block] The graph and table do not reflect the deduction of taxes that a shareholder would pay on Fund distributions or redemption of Fund shares.
Updated Performance Information Location [Text Block] Visit newyorklifeinvestments.com/funds for the most recent performance information.
Net Assets $ 8,898,665,906
Holdings Count | Holding 1,067
Investment Company Portfolio Turnover 37.00%
Additional Fund Statistics [Text Block]
Key Fund Statistics
Fund's net assets $8,898,665,906%
Total number of portfolio holdings 1,067%
Portfolio turnover rate 37%
Holdings [Text Block]
Graphical Representation of Holdings
The tables below show the investment makeup of the Fund; percentages indicated are based on the Fund's net assets.
Top Ten Holdings and/or Issuers*
Los Angeles Department of Water & Power, 3.65%-6.603%, due 7/1/28-7/1/55 3.5%
San Francisco City & County Airport Commission, 5.00%-5.50%, due 5/1/30-5/1/55 2.5%
New York City Transitional Finance Authority, 3.00%-5.50%, due 11/1/36-5/1/53 2.4%
California Community Choice Financing Authority, 4.00%-5.25%, due 2/1/52-11/1/55 2.2%
Black Belt Energy Gas District, 4.00%-5.50%, due 6/1/49-5/1/55 1.9%
New York State Dormitory Authority, 3.00%-5.75%, due 7/1/27-7/1/54 1.9%
Main Street Natural Gas, Inc., 4.00%-5.50%, due 9/15/27-5/1/55 1.5%
Triborough Bridge & Tunnel Authority, 3.00%-5.50%, due 3/15/27-5/15/63 1.5%
New Hampshire Business Finance Authority, 3.00%-6.89%, due 4/1/34-7/1/54 1.5%
Southeast Energy Authority A Cooperative District, 4.00%-5.25%, due 11/1/35-1/1/56 1.4%
* Excluding short-term investments
Top States
California 15.1%
New York 13.9%
Texas 9.9%
Illinois 6.7%
Florida 5.6%
Alabama 4.9%
Georgia 3.8%
Pennsylvania 2.6%
Colorado 2.5%
Utah 2.4%
Largest Holdings [Text Block]
Top Ten Holdings and/or Issuers*
Los Angeles Department of Water & Power, 3.65%-6.603%, due 7/1/28-7/1/55 3.5%
San Francisco City & County Airport Commission, 5.00%-5.50%, due 5/1/30-5/1/55 2.5%
New York City Transitional Finance Authority, 3.00%-5.50%, due 11/1/36-5/1/53 2.4%
California Community Choice Financing Authority, 4.00%-5.25%, due 2/1/52-11/1/55 2.2%
Black Belt Energy Gas District, 4.00%-5.50%, due 6/1/49-5/1/55 1.9%
New York State Dormitory Authority, 3.00%-5.75%, due 7/1/27-7/1/54 1.9%
Main Street Natural Gas, Inc., 4.00%-5.50%, due 9/15/27-5/1/55 1.5%
Triborough Bridge & Tunnel Authority, 3.00%-5.50%, due 3/15/27-5/15/63 1.5%
New Hampshire Business Finance Authority, 3.00%-6.89%, due 4/1/34-7/1/54 1.5%
Southeast Energy Authority A Cooperative District, 4.00%-5.25%, due 11/1/35-1/1/56 1.4%
* Excluding short-term investments
C000018703 [Member]  
Shareholder Report [Line Items]  
Fund Name NYLI MacKay Convertible Fund
Class Name Class A
Trading Symbol MCOAX
Annual or Semi-Annual Statement [Text Block] This semiannual shareholder report contains important information about NYLI MacKay Convertible Fund (the "Fund") for the period November 1, 2024 to April 30, 2025.
Shareholder Report Annual or Semi-Annual semi-annual shareholder report
Additional Information [Text Block] You can find additional information about the Fund at dfinview.com/NYLIM. You can also request this information by contacting us at 800-624-6782.
Additional Information Phone Number 800-624-6782
Additional Information Website dfinview.com/NYLIM
Expenses [Text Block]
What were the Fund costs for the last six months?
(Based on a hypothetical $10,000 investment)
Share Class Name Costs of a $10,000 investment Costs paid as a percentage
of a $10,000 investment1
Class A $46 0.93%
1.
Annualized.
Expenses Paid, Amount $ 46
Expense Ratio, Percent 0.93% [38]
Performance Past Does Not Indicate Future [Text] Keep in mind that the Fund ’s past performance is not a good predictor of how the Fund will perform in the future.
Line Graph [Table Text Block]
Fund Performance
The following graph compares the initial and subsequent account values at the end of each of the most recently completed 10 semiannual reporting periods of the Fund (or for the life of the Fund, if shorter). It assumes a $15,000 initial investment at the beginning of the first fiscal period in an appropriate, broad-based securities market index and other additional indexes, if applicable, for the same period and reflects the deduction of all sales charges, where applicable.
Fund Performance - Growth of 10K
Average Annual Return [Table Text Block]
Average Annual Total Returns for the Period Ended April 30, 2025 Inception
Date		 Six
Months1		 One
Year		 Five
Years		 Ten
Years
Class A Shares - Including sales charges 1/3/1995 (6.13)% 0.95% 8.46% 7.13%
Class A Shares - Excluding sales charges (0.67)% 6.82% 9.70% 7.74%
Bloomberg U.S. Aggregate Bond Index2 2.57% 8.02% (0.67)% 1.54%
ICE BofA U.S. Convertible Index3 1.67% 11.59% 10.38% 8.57%
Morningstar Convertibles Category Average4 1.08% 9.86% 8.32% 7.10%
1.
Not annualized.
2.
The Fund has selected the Bloomberg U.S. Aggregate Bond Index to represent a broad measure of market performance. The Bloomberg U.S. Aggregate Bond Index is a broad-based benchmark that measures the investment grade, U.S. dollar-denominated, fixed-rate taxable bond market, including Treasuries, government-related and corporate securities, mortgage-backed securities (agency fixed-rate and hybrid adjustable rate mortgage pass-throughs), asset-backed securities and commercial mortgage-backed securities.
3.
The ICE BofA U.S. Convertible Index, which is generally representative of the market sectors or types of investments in which the Fund invests, is a market-capitalization weighted index of domestic corporate convertible securities. In order to be included in the ICE BofA U.S. Convertible Index, bonds and preferred stocks must be convertible only to common stock.
4.
The Morningstar Convertibles Category Average is representative of funds that are designed to offer some of the capital-appreciation potential of stock funds while also supplying some of the safety and yield of bond funds. Results are based on average total returns of similar funds with all dividends and capital gain distributions reinvested.
Performance Inception Date Jan. 03, 1995
No Deduction of Taxes [Text Block] The graph and table do not reflect the deduction of taxes that a shareholder would pay on Fund distributions or redemption of Fund shares.
Updated Performance Information Location [Text Block] Visit newyorklifeinvestments.com/funds for the most recent performance information.
Net Assets $ 1,453,869,493
Holdings Count | Holding 105
Investment Company Portfolio Turnover 17.00%
Additional Fund Statistics [Text Block]
Key Fund Statistics
Fund's net assets $1,453,869,493%
Total number of portfolio holdings 105%
Portfolio turnover rate 17%
Holdings [Text Block]
Graphical Representation of Holdings
The tables below show the investment makeup of the Fund; percentages indicated are based on the Fund's net assets.
Top Ten Holdings and/or Issuers*
NRG Energy, Inc., 2.75%, due 6/1/48 2.6%
Lantheus Holdings, Inc., 2.625%, due 12/15/27 2.4%
Merit Medical Systems, Inc., 3.00%, due 2/1/29 2.1%
Tetra Tech, Inc., 2.25%, due 8/15/28 2.0%
Post Holdings, Inc., 2.50%, due 8/15/27 1.9%
Southwest Airlines Co., 1.25%, due 5/1/25 1.9%
Integer Holdings Corp., 1.875%, due 3/15/30 1.9%
Booking Holdings, Inc., 0.75%, due 5/1/25 1.8%
PG&E Corp., 4.25%, due 12/1/27 1.8%
Welltower OP LLC, 3.125%, due 7/15/29 1.6%
* Excluding short-term investments
Portfolio Composition 
Convertible Bonds 86.9%
Convertible Preferred Stocks 8.4%
Short-Term Investments 3.7%
Common Stock 0.5%
Other Assets, Less Liabilities 0.5%
Largest Holdings [Text Block]
Top Ten Holdings and/or Issuers*
NRG Energy, Inc., 2.75%, due 6/1/48 2.6%
Lantheus Holdings, Inc., 2.625%, due 12/15/27 2.4%
Merit Medical Systems, Inc., 3.00%, due 2/1/29 2.1%
Tetra Tech, Inc., 2.25%, due 8/15/28 2.0%
Post Holdings, Inc., 2.50%, due 8/15/27 1.9%
Southwest Airlines Co., 1.25%, due 5/1/25 1.9%
Integer Holdings Corp., 1.875%, due 3/15/30 1.9%
Booking Holdings, Inc., 0.75%, due 5/1/25 1.8%
PG&E Corp., 4.25%, due 12/1/27 1.8%
Welltower OP LLC, 3.125%, due 7/15/29 1.6%
* Excluding short-term investments
C000018705 [Member]  
Shareholder Report [Line Items]  
Fund Name NYLI MacKay Convertible Fund
Class Name Class C
Trading Symbol MCCVX
Annual or Semi-Annual Statement [Text Block] This semiannual shareholder report contains important information about NYLI MacKay Convertible Fund (the "Fund") for the period November 1, 2024 to April 30, 2025.
Shareholder Report Annual or Semi-Annual semi-annual shareholder report
Additional Information [Text Block] You can find additional information about the Fund at dfinview.com/NYLIM. You can also request this information by contacting us at 800-624-6782.
Additional Information Phone Number 800-624-6782
Additional Information Website dfinview.com/NYLIM
Expenses [Text Block]
What were the Fund costs for the last six months?
(Based on a hypothetical $10,000 investment)
Share Class Name Costs of a $10,000 investment Costs paid as a percentage
of a $10,000 investment1
Class C $95 1.93%
1.
Annualized.
Expenses Paid, Amount $ 95
Expense Ratio, Percent 1.93% [39]
Performance Past Does Not Indicate Future [Text] Keep in mind that the Fund ’s past performance is not a good predictor of how the Fund will perform in the future.
Line Graph [Table Text Block]
Fund Performance
The following graph compares the initial and subsequent account values at the end of each of the most recently completed 10 semiannual reporting periods of the Fund (or for the life of the Fund, if shorter). It assumes a $10,000 initial investment at the beginning of the first fiscal period in an appropriate, broad-based securities market index and other additional indexes, if applicable, for the same period and reflects the deduction of all sales charges, where applicable.
Fund Performance - Growth of 10K
Average Annual Return [Table Text Block]
Average Annual Total Returns for the Period Ended April 30, 2025 Inception
Date		 Six
Months1		 One
Year		 Five
Years		 Ten
Years
Class C Shares - Including sales charges 9/1/1998 (2.11)% 4.77% 8.65% 6.74%
Class C Shares - Excluding sales charges (1.16)% 5.77% 8.65% 6.74%
Bloomberg U.S. Aggregate Bond Index2 2.57% 8.02% (0.67)% 1.54%
ICE BofA U.S. Convertible Index3 1.67% 11.59% 10.38% 8.57%
Morningstar Convertibles Category Average4 1.08% 9.86% 8.32% 7.10%
1.
Not annualized.
2.
The Fund has selected the Bloomberg U.S. Aggregate Bond Index to represent a broad measure of market performance. The Bloomberg U.S. Aggregate Bond Index is a broad-based benchmark that measures the investment grade, U.S. dollar-denominated, fixed-rate taxable bond market, including Treasuries, government-related and corporate securities, mortgage-backed securities (agency fixed-rate and hybrid adjustable rate mortgage pass-throughs), asset-backed securities and commercial mortgage-backed securities.
3.
The ICE BofA U.S. Convertible Index, which is generally representative of the market sectors or types of investments in which the Fund invests, is a market-capitalization weighted index of domestic corporate convertible securities. In order to be included in the ICE BofA U.S. Convertible Index, bonds and preferred stocks must be convertible only to common stock.
4.
The Morningstar Convertibles Category Average is representative of funds that are designed to offer some of the capital-appreciation potential of stock funds while also supplying some of the safety and yield of bond funds. Results are based on average total returns of similar funds with all dividends and capital gain distributions reinvested.
Performance Inception Date Sep. 01, 1998
No Deduction of Taxes [Text Block] The graph and table do not reflect the deduction of taxes that a shareholder would pay on Fund distributions or redemption of Fund shares.
Updated Performance Information Location [Text Block] Visit newyorklifeinvestments.com/funds for the most recent performance information.
Net Assets $ 1,453,869,493
Holdings Count | Holding 105
Investment Company Portfolio Turnover 17.00%
Additional Fund Statistics [Text Block]
Key Fund Statistics
Fund's net assets $1,453,869,493%
Total number of portfolio holdings 105%
Portfolio turnover rate 17%
Holdings [Text Block]
Graphical Representation of Holdings
The tables below show the investment makeup of the Fund; percentages indicated are based on the Fund's net assets.
Top Ten Holdings and/or Issuers*
NRG Energy, Inc., 2.75%, due 6/1/48 2.6%
Lantheus Holdings, Inc., 2.625%, due 12/15/27 2.4%
Merit Medical Systems, Inc., 3.00%, due 2/1/29 2.1%
Tetra Tech, Inc., 2.25%, due 8/15/28 2.0%
Post Holdings, Inc., 2.50%, due 8/15/27 1.9%
Southwest Airlines Co., 1.25%, due 5/1/25 1.9%
Integer Holdings Corp., 1.875%, due 3/15/30 1.9%
Booking Holdings, Inc., 0.75%, due 5/1/25 1.8%
PG&E Corp., 4.25%, due 12/1/27 1.8%
Welltower OP LLC, 3.125%, due 7/15/29 1.6%
* Excluding short-term investments
Portfolio Composition 
Convertible Bonds 86.9%
Convertible Preferred Stocks 8.4%
Short-Term Investments 3.7%
Common Stock 0.5%
Other Assets, Less Liabilities 0.5%
Largest Holdings [Text Block]
Top Ten Holdings and/or Issuers*
NRG Energy, Inc., 2.75%, due 6/1/48 2.6%
Lantheus Holdings, Inc., 2.625%, due 12/15/27 2.4%
Merit Medical Systems, Inc., 3.00%, due 2/1/29 2.1%
Tetra Tech, Inc., 2.25%, due 8/15/28 2.0%
Post Holdings, Inc., 2.50%, due 8/15/27 1.9%
Southwest Airlines Co., 1.25%, due 5/1/25 1.9%
Integer Holdings Corp., 1.875%, due 3/15/30 1.9%
Booking Holdings, Inc., 0.75%, due 5/1/25 1.8%
PG&E Corp., 4.25%, due 12/1/27 1.8%
Welltower OP LLC, 3.125%, due 7/15/29 1.6%
* Excluding short-term investments
C000087595 [Member]  
Shareholder Report [Line Items]  
Fund Name NYLI MacKay Convertible Fund
Class Name Class I
Trading Symbol MCNVX
Annual or Semi-Annual Statement [Text Block] This semiannual shareholder report contains important information about NYLI MacKay Convertible Fund (the "Fund") for the period November 1, 2024 to April 30, 2025.
Shareholder Report Annual or Semi-Annual semi-annual shareholder report
Additional Information [Text Block] You can find additional information about the Fund at dfinview.com/NYLIM. You can also request this information by contacting us at 800-624-6782.
Additional Information Phone Number 800-624-6782
Additional Information Website dfinview.com/NYLIM
Expenses [Text Block]
What were the Fund costs for the last six months?
(Based on a hypothetical $10,000 investment)
Share Class Name Costs of a $10,000 investment Costs paid as a percentage
of a $10,000 investment1,2
Class I $30 0.61%
1.
Reflects fee waivers and/or expense reimbursements, without which expenses would have been higher.
2.
Annualized.
Expenses Paid, Amount $ 30
Expense Ratio, Percent 0.61% [40],[41]
Performance Past Does Not Indicate Future [Text] Keep in mind that the Fund ’s past performance is not a good predictor of how the Fund will perform in the future.
Line Graph [Table Text Block]
Fund Performance
The following graph compares the initial and subsequent account values at the end of each of the most recently completed 10 semiannual reporting periods of the Fund (or for the life of the Fund, if shorter). It assumes a $10,000 initial investment at the beginning of the first fiscal period in an appropriate, broad-based securities market index and other additional indexes, if applicable, for the same period and reflects the deduction of all sales charges, where applicable.
Fund Performance - Growth of 10K
Average Annual Return [Table Text Block]
Average Annual Total Returns for the Period Ended April 30, 2025 Inception
Date		 Six
Months1		 One
Year		 Five
Years		 Ten
Years
Class I Shares 11/28/2008 (0.50)% 7.14% 10.05% 8.10%
Bloomberg U.S. Aggregate Bond Index2 2.57% 8.02% (0.67)% 1.54%
ICE BofA U.S. Convertible Index3 1.67% 11.59% 10.38% 8.57%
Morningstar Convertibles Category Average4 1.08% 9.86% 8.32% 7.10%
1.
Not annualized.
2.
The Fund has selected the Bloomberg U.S. Aggregate Bond Index to represent a broad measure of market performance. The Bloomberg U.S. Aggregate Bond Index is a broad-based benchmark that measures the investment grade, U.S. dollar-denominated, fixed-rate taxable bond market, including Treasuries, government-related and corporate securities, mortgage-backed securities (agency fixed-rate and hybrid adjustable rate mortgage pass-throughs), asset-backed securities and commercial mortgage-backed securities.
3.
The ICE BofA U.S. Convertible Index, which is generally representative of the market sectors or types of investments in which the Fund invests, is a market-capitalization weighted index of domestic corporate convertible securities. In order to be included in the ICE BofA U.S. Convertible Index, bonds and preferred stocks must be convertible only to common stock.
4.
The Morningstar Convertibles Category Average is representative of funds that are designed to offer some of the capital-appreciation potential of stock funds while also supplying some of the safety and yield of bond funds. Results are based on average total returns of similar funds with all dividends and capital gain distributions reinvested.
Performance Inception Date Nov. 28, 2008
No Deduction of Taxes [Text Block] The graph and table do not reflect the deduction of taxes that a shareholder would pay on Fund distributions or redemption of Fund shares.
Updated Performance Information Location [Text Block] Visit newyorklifeinvestments.com/funds for the most recent performance information.
Net Assets $ 1,453,869,493
Holdings Count | Holding 105
Investment Company Portfolio Turnover 17.00%
Additional Fund Statistics [Text Block]
Key Fund Statistics
Fund's net assets $1,453,869,493%
Total number of portfolio holdings 105%
Portfolio turnover rate 17%
Holdings [Text Block]
Graphical Representation of Holdings
The tables below show the investment makeup of the Fund; percentages indicated are based on the Fund's net assets.
Top Ten Holdings and/or Issuers*
NRG Energy, Inc., 2.75%, due 6/1/48 2.6%
Lantheus Holdings, Inc., 2.625%, due 12/15/27 2.4%
Merit Medical Systems, Inc., 3.00%, due 2/1/29 2.1%
Tetra Tech, Inc., 2.25%, due 8/15/28 2.0%
Post Holdings, Inc., 2.50%, due 8/15/27 1.9%
Southwest Airlines Co., 1.25%, due 5/1/25 1.9%
Integer Holdings Corp., 1.875%, due 3/15/30 1.9%
Booking Holdings, Inc., 0.75%, due 5/1/25 1.8%
PG&E Corp., 4.25%, due 12/1/27 1.8%
Welltower OP LLC, 3.125%, due 7/15/29 1.6%
* Excluding short-term investments
Portfolio Composition 
Convertible Bonds 86.9%
Convertible Preferred Stocks 8.4%
Short-Term Investments 3.7%
Common Stock 0.5%
Other Assets, Less Liabilities 0.5%
Largest Holdings [Text Block]
Top Ten Holdings and/or Issuers*
NRG Energy, Inc., 2.75%, due 6/1/48 2.6%
Lantheus Holdings, Inc., 2.625%, due 12/15/27 2.4%
Merit Medical Systems, Inc., 3.00%, due 2/1/29 2.1%
Tetra Tech, Inc., 2.25%, due 8/15/28 2.0%
Post Holdings, Inc., 2.50%, due 8/15/27 1.9%
Southwest Airlines Co., 1.25%, due 5/1/25 1.9%
Integer Holdings Corp., 1.875%, due 3/15/30 1.9%
Booking Holdings, Inc., 0.75%, due 5/1/25 1.8%
PG&E Corp., 4.25%, due 12/1/27 1.8%
Welltower OP LLC, 3.125%, due 7/15/29 1.6%
* Excluding short-term investments
C000060795 [Member]  
Shareholder Report [Line Items]  
Fund Name NYLI MacKay Convertible Fund
Class Name Investor Class
Trading Symbol MCINX
Annual or Semi-Annual Statement [Text Block] This semiannual shareholder report contains important information about NYLI MacKay Convertible Fund (the "Fund") for the period November 1, 2024 to April 30, 2025.
Shareholder Report Annual or Semi-Annual semi-annual shareholder report
Additional Information [Text Block] You can find additional information about the Fund at dfinview.com/NYLIM. You can also request this information by contacting us at 800-624-6782.
Additional Information Phone Number 800-624-6782
Additional Information Website dfinview.com/NYLIM
Expenses [Text Block]
What were the Fund costs for the last six months?
(Based on a hypothetical $10,000 investment)
Share Class Name Costs of a $10,000 investment Costs paid as a percentage
of a $10,000 investment1
Investor Class $58 1.18%
1.
Annualized.
Expenses Paid, Amount $ 58
Expense Ratio, Percent 1.18% [42]
Performance Past Does Not Indicate Future [Text] Keep in mind that the Fund ’s past performance is not a good predictor of how the Fund will perform in the future.
Line Graph [Table Text Block]
Fund Performance
The following graph compares the initial and subsequent account values at the end of each of the most recently completed 10 semiannual reporting periods of the Fund (or for the life of the Fund, if shorter). It assumes a $10,000 initial investment at the beginning of the first fiscal period in an appropriate, broad-based securities market index and other additional indexes, if applicable, for the same period and reflects the deduction of all sales charges, where applicable.
Fund Performance - Growth of 10K
Average Annual Return [Table Text Block]
Average Annual Total Returns for the Period Ended April 30, 2025 Inception
Date		 Six
Months1		 One
Year		 Five
Years		 Ten
Years
Investor Class Shares - Including sales charges 2/28/2008 (5.70)% 1.27% 8.24% 6.93%
Investor Class Shares - Excluding sales charges (0.74)% 6.60% 9.47% 7.54%
Bloomberg U.S. Aggregate Bond Index2 2.57% 8.02% (0.67)% 1.54%
ICE BofA U.S. Convertible Index3 1.67% 11.59% 10.38% 8.57%
Morningstar Convertibles Category Average4 1.08% 9.86% 8.32% 7.10%
1.
Not annualized.
2.
The Fund has selected the Bloomberg U.S. Aggregate Bond Index to represent a broad measure of market performance. The Bloomberg U.S. Aggregate Bond Index is a broad-based benchmark that measures the investment grade, U.S. dollar-denominated, fixed-rate taxable bond market, including Treasuries, government-related and corporate securities, mortgage-backed securities (agency fixed-rate and hybrid adjustable rate mortgage pass-throughs), asset-backed securities and commercial mortgage-backed securities.
3.
The ICE BofA U.S. Convertible Index, which is generally representative of the market sectors or types of investments in which the Fund invests, is a market-capitalization weighted index of domestic corporate convertible securities. In order to be included in the ICE BofA U.S. Convertible Index, bonds and preferred stocks must be convertible only to common stock.
4.
The Morningstar Convertibles Category Average is representative of funds that are designed to offer some of the capital-appreciation potential of stock funds while also supplying some of the safety and yield of bond funds. Results are based on average total returns of similar funds with all dividends and capital gain distributions reinvested.
Performance Inception Date Feb. 28, 2008
No Deduction of Taxes [Text Block] The graph and table do not reflect the deduction of taxes that a shareholder would pay on Fund distributions or redemption of Fund shares.
Updated Performance Information Location [Text Block] Visit newyorklifeinvestments.com/funds for the most recent performance information.
Net Assets $ 1,453,869,493
Holdings Count | Holding 105
Investment Company Portfolio Turnover 17.00%
Additional Fund Statistics [Text Block]
Key Fund Statistics
Fund's net assets $1,453,869,493%
Total number of portfolio holdings 105%
Portfolio turnover rate 17%
Holdings [Text Block]
Graphical Representation of Holdings
The tables below show the investment makeup of the Fund; percentages indicated are based on the Fund's net assets.
Top Ten Holdings and/or Issuers*
NRG Energy, Inc., 2.75%, due 6/1/48 2.6%
Lantheus Holdings, Inc., 2.625%, due 12/15/27 2.4%
Merit Medical Systems, Inc., 3.00%, due 2/1/29 2.1%
Tetra Tech, Inc., 2.25%, due 8/15/28 2.0%
Post Holdings, Inc., 2.50%, due 8/15/27 1.9%
Southwest Airlines Co., 1.25%, due 5/1/25 1.9%
Integer Holdings Corp., 1.875%, due 3/15/30 1.9%
Booking Holdings, Inc., 0.75%, due 5/1/25 1.8%
PG&E Corp., 4.25%, due 12/1/27 1.8%
Welltower OP LLC, 3.125%, due 7/15/29 1.6%
* Excluding short-term investments
Portfolio Composition 
Convertible Bonds 86.9%
Convertible Preferred Stocks 8.4%
Short-Term Investments 3.7%
Common Stock 0.5%
Other Assets, Less Liabilities 0.5%
Largest Holdings [Text Block]
Top Ten Holdings and/or Issuers*
NRG Energy, Inc., 2.75%, due 6/1/48 2.6%
Lantheus Holdings, Inc., 2.625%, due 12/15/27 2.4%
Merit Medical Systems, Inc., 3.00%, due 2/1/29 2.1%
Tetra Tech, Inc., 2.25%, due 8/15/28 2.0%
Post Holdings, Inc., 2.50%, due 8/15/27 1.9%
Southwest Airlines Co., 1.25%, due 5/1/25 1.9%
Integer Holdings Corp., 1.875%, due 3/15/30 1.9%
Booking Holdings, Inc., 0.75%, due 5/1/25 1.8%
PG&E Corp., 4.25%, due 12/1/27 1.8%
Welltower OP LLC, 3.125%, due 7/15/29 1.6%
* Excluding short-term investments
C000018706 [Member]  
Shareholder Report [Line Items]  
Fund Name NYLI Income Builder Fund
Class Name Class A
Trading Symbol MTRAX
Annual or Semi-Annual Statement [Text Block] This semiannual shareholder report contains important information about NYLI Income Builder Fund (the "Fund") for the period November 1, 2024 to April 30, 2025.
Shareholder Report Annual or Semi-Annual semi-annual shareholder report
Additional Information [Text Block] You can find additional information about the Fund at dfinview.com/NYLIM. You can also request this information by contacting us at 800-624-6782.
Additional Information Phone Number 800-624-6782
Additional Information Website dfinview.com/NYLIM
Expenses [Text Block]
What were the Fund costs for the last six months?
(Based on a hypothetical $10,000 investment)
Share Class Name Costs of a $10,000 investment Costs paid as a percentage
of a $10,000 investment1
Class A $51 1.02%
1.
Annualized.
Expenses Paid, Amount $ 51
Expense Ratio, Percent 1.02% [43]
Performance Past Does Not Indicate Future [Text] Keep in mind that the Fund ’s past performance is not a good predictor of how the Fund will perform in the future.
Line Graph [Table Text Block]
Fund Performance
The following graph compares the initial and subsequent account values at the end of each of the most recently completed 10 semiannual reporting periods of the Fund (or for the life of the Fund, if shorter). It assumes a $15,000 initial investment at the beginning of the first fiscal period in an appropriate, broad-based securities market index and other additional indexes, if applicable, for the same period and reflects the deduction of all sales charges, where applicable.
Fund Performance - Growth of 10K
Average Annual Return [Table Text Block]
Average Annual Total Returns for the Period Ended April 30, 2025 Inception
Date		 Six
Months1		 One
Year		 Five
Years		 Ten
Years
Class A Shares - Including sales charges 1/3/1995 (1.99)% 8.96% 6.20% 4.37%
Class A Shares - Excluding sales charges 1.05% 12.33% 6.85% 4.96%
MSCI World Index (Net)2 0.93% 12.16% 13.95% 9.34%
Bloomberg U.S. Aggregate Bond Index3 2.57% 8.02% (0.67)% 1.54%
Blended Benchmark Index4 1.64% 10.56% 8.08% 6.40%
Morningstar Global Moderate Allocation Category Average5 (1.07)% 8.64% 7.97% 4.90%
1.
Not annualized.
2.
The Fund has selected the MSCI World Index (Net) to represent a broad measure of market performance. The MSCI World Index (Net) is a free float-adjusted market capitalization weighted index that is designed to measure the equity market performance of developed markets.
3.
The Bloomberg U.S. Aggregate Bond Index is a broad-based benchmark that measures performance of the investment-grade, U.S. dollar-denominated, fixed-rate taxable bond market, including Treasuries, government-related and corporate securities, mortgage-backed securities (agency fixed-rate and hybrid adjustable-rate mortgage pass-throughs), asset-backed securities and commercial mortgage-backed securities.
4.
The Blended Benchmark Index is comprised of the MSCI World Index (Net) and the Bloomberg U.S. Aggregate Bond Index weighted 60%/40%.
5.
Morningstar Global Moderate Allocation Category Average funds seek to provide both income and capital appreciation by primarily investing in multiple asset classes, including stocks, bonds, and cash. These moderate strategies seek to balance preservation of capital with appreciation. They typically expect volatility similar to a strategic equity exposure between 50% and 70%. Results are based on average total returns of similar funds with all dividends and capital gain distributions reinvested.
Performance Inception Date Jan. 03, 1995
No Deduction of Taxes [Text Block] The graph and table do not reflect the deduction of taxes that a shareholder would pay on Fund distributions or redemption of Fund shares.
Updated Performance Information Location [Text Block] Visit newyorklifeinvestments.com/funds for the most recent performance information.
Net Assets $ 1,001,362,966
Holdings Count | Holding 561
Investment Company Portfolio Turnover 19.00%
Additional Fund Statistics [Text Block]
Key Fund Statistics
Fund's net assets $1,001,362,966%
Total number of portfolio holdings 561%
Portfolio turnover rate 19%
Holdings [Text Block]
Graphical Representation of Holdings
The tables below show the investment makeup of the Fund; percentages indicated are based on the Fund's net assets.
Top Ten Holdings and/or Issuers*
GNMA, (zero coupon)-7.764%, due 7/20/44-2/16/66 3.1%
UMBS, 30 Year, 2.00%-6.50%, due 8/1/48-9/1/54 2.0%
Broadcom, Inc. 1.4%
Microsoft Corp. 1.4%
Connecticut Avenue Securities Trust, 6.053%-14.204%, due 11/25/39-2/25/45 1.4%
AbbVie, Inc. 1.3%
International Business Machines Corp. 1.3%
FHLMC STACR REMIC Trust, 6.004%-11.454%, due 9/25/41-1/25/50 1.3%
Cisco Systems, Inc. 1.2%
Philip Morris International, Inc. 1.2%
* Excluding short-term investments
Portfolio Composition 
Common Stocks 62.0%
Mortgage-Backed Securities 13.2%
Corporate Bonds 12.3%
U.S. Government & Federal Agencies 4.5%
Asset-Backed Securities 3.6%
Short-Term Investments 2.4%
Foreign Government Bonds 0.6%
Loan Assignments 0.4%
Other Assets, Less Liabilities 1.0%
Largest Holdings [Text Block]
Top Ten Holdings and/or Issuers*
GNMA, (zero coupon)-7.764%, due 7/20/44-2/16/66 3.1%
UMBS, 30 Year, 2.00%-6.50%, due 8/1/48-9/1/54 2.0%
Broadcom, Inc. 1.4%
Microsoft Corp. 1.4%
Connecticut Avenue Securities Trust, 6.053%-14.204%, due 11/25/39-2/25/45 1.4%
AbbVie, Inc. 1.3%
International Business Machines Corp. 1.3%
FHLMC STACR REMIC Trust, 6.004%-11.454%, due 9/25/41-1/25/50 1.3%
Cisco Systems, Inc. 1.2%
Philip Morris International, Inc. 1.2%
* Excluding short-term investments
C000018708 [Member]  
Shareholder Report [Line Items]  
Fund Name NYLI Income Builder Fund
Class Name Class C
Trading Symbol MCTRX
Annual or Semi-Annual Statement [Text Block] This semiannual shareholder report contains important information about NYLI Income Builder Fund (the "Fund") for the period November 1, 2024 to April 30, 2025.
Shareholder Report Annual or Semi-Annual semi-annual shareholder report
Additional Information [Text Block] You can find additional information about the Fund at dfinview.com/NYLIM. You can also request this information by contacting us at 800-624-6782.
Additional Information Phone Number 800-624-6782
Additional Information Website dfinview.com/NYLIM
Expenses [Text Block]
What were the Fund costs for the last six months?
(Based on a hypothetical $10,000 investment)
Share Class Name Costs of a $10,000 investment Costs paid as a percentage
of a $10,000 investment1,2
Class C $101 2.03%
1.
Reflects fee waivers and/or expense reimbursements, without which expenses would have been higher.
2.
Annualized.
Expenses Paid, Amount $ 101
Expense Ratio, Percent 2.03% [44],[45]
Performance Past Does Not Indicate Future [Text] Keep in mind that the Fund ’s past performance is not a good predictor of how the Fund will perform in the future.
Line Graph [Table Text Block]
Fund Performance
The following graph compares the initial and subsequent account values at the end of each of the most recently completed 10 semiannual reporting periods of the Fund (or for the life of the Fund, if shorter). It assumes a $10,000 initial investment at the beginning of the first fiscal period in an appropriate, broad-based securities market index and other additional indexes, if applicable, for the same period and reflects the deduction of all sales charges, where applicable.
Fund Performance - Growth of 10K
Average Annual Return [Table Text Block]
Average Annual Total Returns for the Period Ended April 30, 2025 Inception
Date		 Six
Months1		 One
Year		 Five
Years		 Ten
Years
Class C Shares - Including sales charges 9/1/1998 (0.44)% 10.23% 5.82% 3.99%
Class C Shares - Excluding sales charges 0.56% 11.23% 5.82% 3.99%
MSCI World Index (Net)2 0.93% 12.16% 13.95% 9.34%
Bloomberg U.S. Aggregate Bond Index3 2.57% 8.02% (0.67)% 1.54%
Blended Benchmark Index4 1.64% 10.56% 8.08% 6.40%
Morningstar Global Moderate Allocation Category Average5 (1.07)% 8.64% 7.97% 4.90%
1.
Not annualized.
2.
The Fund has selected the MSCI World Index (Net) to represent a broad measure of market performance. The MSCI World Index (Net) is a free float-adjusted market capitalization weighted index that is designed to measure the equity market performance of developed markets.
3.
The Bloomberg U.S. Aggregate Bond Index is a broad-based benchmark that measures performance of the investment-grade, U.S. dollar-denominated, fixed-rate taxable bond market, including Treasuries, government-related and corporate securities, mortgage-backed securities (agency fixed-rate and hybrid adjustable-rate mortgage pass-throughs), asset-backed securities and commercial mortgage-backed securities.
4.
The Blended Benchmark Index is comprised of the MSCI World Index (Net) and the Bloomberg U.S. Aggregate Bond Index weighted 60%/40%.
5.
Morningstar Global Moderate Allocation Category Average funds seek to provide both income and capital appreciation by primarily investing in multiple asset classes, including stocks, bonds, and cash. These moderate strategies seek to balance preservation of capital with appreciation. They typically expect volatility similar to a strategic equity exposure between 50% and 70%. Results are based on average total returns of similar funds with all dividends and capital gain distributions reinvested.
Performance Inception Date Sep. 01, 1998
No Deduction of Taxes [Text Block] The graph and table do not reflect the deduction of taxes that a shareholder would pay on Fund distributions or redemption of Fund shares.
Updated Performance Information Location [Text Block] Visit newyorklifeinvestments.com/funds for the most recent performance information.
Net Assets $ 1,001,362,966
Holdings Count | Holding 561
Investment Company Portfolio Turnover 19.00%
Additional Fund Statistics [Text Block]
Key Fund Statistics
Fund's net assets $1,001,362,966%
Total number of portfolio holdings 561%
Portfolio turnover rate 19%
Holdings [Text Block]
Graphical Representation of Holdings
The tables below show the investment makeup of the Fund; percentages indicated are based on the Fund's net assets.
Top Ten Holdings and/or Issuers*
GNMA, (zero coupon)-7.764%, due 7/20/44-2/16/66 3.1%
UMBS, 30 Year, 2.00%-6.50%, due 8/1/48-9/1/54 2.0%
Broadcom, Inc. 1.4%
Microsoft Corp. 1.4%
Connecticut Avenue Securities Trust, 6.053%-14.204%, due 11/25/39-2/25/45 1.4%
AbbVie, Inc. 1.3%
International Business Machines Corp. 1.3%
FHLMC STACR REMIC Trust, 6.004%-11.454%, due 9/25/41-1/25/50 1.3%
Cisco Systems, Inc. 1.2%
Philip Morris International, Inc. 1.2%
* Excluding short-term investments
Portfolio Composition 
Common Stocks 62.0%
Mortgage-Backed Securities 13.2%
Corporate Bonds 12.3%
U.S. Government & Federal Agencies 4.5%
Asset-Backed Securities 3.6%
Short-Term Investments 2.4%
Foreign Government Bonds 0.6%
Loan Assignments 0.4%
Other Assets, Less Liabilities 1.0%
Largest Holdings [Text Block]
Top Ten Holdings and/or Issuers*
GNMA, (zero coupon)-7.764%, due 7/20/44-2/16/66 3.1%
UMBS, 30 Year, 2.00%-6.50%, due 8/1/48-9/1/54 2.0%
Broadcom, Inc. 1.4%
Microsoft Corp. 1.4%
Connecticut Avenue Securities Trust, 6.053%-14.204%, due 11/25/39-2/25/45 1.4%
AbbVie, Inc. 1.3%
International Business Machines Corp. 1.3%
FHLMC STACR REMIC Trust, 6.004%-11.454%, due 9/25/41-1/25/50 1.3%
Cisco Systems, Inc. 1.2%
Philip Morris International, Inc. 1.2%
* Excluding short-term investments
C000018709 [Member]  
Shareholder Report [Line Items]  
Fund Name NYLI Income Builder Fund
Class Name Class I
Trading Symbol MTOIX
Annual or Semi-Annual Statement [Text Block] This semiannual shareholder report contains important information about NYLI Income Builder Fund (the "Fund") for the period November 1, 2024 to April 30, 2025.
Shareholder Report Annual or Semi-Annual semi-annual shareholder report
Additional Information [Text Block] You can find additional information about the Fund at dfinview.com/NYLIM. You can also request this information by contacting us at 800-624-6782.
Additional Information Phone Number 800-624-6782
Additional Information Website dfinview.com/NYLIM
Expenses [Text Block]
What were the Fund costs for the last six months?
(Based on a hypothetical $10,000 investment)
Share Class Name Costs of a $10,000 investment Costs paid as a percentage
of a $10,000 investment1
Class I $38 0.77%
1.
Annualized.
Expenses Paid, Amount $ 38
Expense Ratio, Percent 0.77% [46]
Performance Past Does Not Indicate Future [Text] Keep in mind that the Fund ’s past performance is not a good predictor of how the Fund will perform in the future.
Line Graph [Table Text Block]
Fund Performance
The following graph compares the initial and subsequent account values at the end of each of the most recently completed 10 semiannual reporting periods of the Fund (or for the life of the Fund, if shorter). It assumes a $10,000 initial investment at the beginning of the first fiscal period in an appropriate, broad-based securities market index and other additional indexes, if applicable, for the same period and reflects the deduction of all sales charges, where applicable.
Fund Performance - Growth of 10K
Average Annual Return [Table Text Block]
Average Annual Total Returns for the Period Ended April 30, 2025 Inception
Date		 Six
Months1		 One
Year		 Five
Years		 Ten
Years
Class I Shares 1/2/2004 1.21% 12.61% 7.12% 5.23%
MSCI World Index (Net)2 0.93% 12.16% 13.95% 9.34%
Bloomberg U.S. Aggregate Bond Index3 2.57% 8.02% (0.67)% 1.54%
Blended Benchmark Index4 1.64% 10.56% 8.08% 6.40%
Morningstar Global Moderate Allocation Category Average5 (1.07)% 8.64% 7.97% 4.90%
1.
Not annualized.
2.
The Fund has selected the MSCI World Index (Net) to represent a broad measure of market performance. The MSCI World Index (Net) is a free float-adjusted market capitalization weighted index that is designed to measure the equity market performance of developed markets.
3.
The Bloomberg U.S. Aggregate Bond Index is a broad-based benchmark that measures performance of the investment-grade, U.S. dollar-denominated, fixed-rate taxable bond market, including Treasuries, government-related and corporate securities, mortgage-backed securities (agency fixed-rate and hybrid adjustable-rate mortgage pass-throughs), asset-backed securities and commercial mortgage-backed securities.
4.
The Blended Benchmark Index is comprised of the MSCI World Index (Net) and the Bloomberg U.S. Aggregate Bond Index weighted 60%/40%.
5.
Morningstar Global Moderate Allocation Category Average funds seek to provide both income and capital appreciation by primarily investing in multiple asset classes, including stocks, bonds, and cash. These moderate strategies seek to balance preservation of capital with appreciation. They typically expect volatility similar to a strategic equity exposure between 50% and 70%. Results are based on average total returns of similar funds with all dividends and capital gain distributions reinvested.
Performance Inception Date Jan. 02, 2004
No Deduction of Taxes [Text Block] The graph and table do not reflect the deduction of taxes that a shareholder would pay on Fund distributions or redemption of Fund shares.
Updated Performance Information Location [Text Block] Visit newyorklifeinvestments.com/funds for the most recent performance information.
Net Assets $ 1,001,362,966
Holdings Count | Holding 561
Investment Company Portfolio Turnover 19.00%
Additional Fund Statistics [Text Block]
Key Fund Statistics
Fund's net assets $1,001,362,966%
Total number of portfolio holdings 561%
Portfolio turnover rate 19%
Holdings [Text Block]
Graphical Representation of Holdings
The tables below show the investment makeup of the Fund; percentages indicated are based on the Fund's net assets.
Top Ten Holdings and/or Issuers*
GNMA, (zero coupon)-7.764%, due 7/20/44-2/16/66 3.1%
UMBS, 30 Year, 2.00%-6.50%, due 8/1/48-9/1/54 2.0%
Broadcom, Inc. 1.4%
Microsoft Corp. 1.4%
Connecticut Avenue Securities Trust, 6.053%-14.204%, due 11/25/39-2/25/45 1.4%
AbbVie, Inc. 1.3%
International Business Machines Corp. 1.3%
FHLMC STACR REMIC Trust, 6.004%-11.454%, due 9/25/41-1/25/50 1.3%
Cisco Systems, Inc. 1.2%
Philip Morris International, Inc. 1.2%
* Excluding short-term investments
Portfolio Composition 
Common Stocks 62.0%
Mortgage-Backed Securities 13.2%
Corporate Bonds 12.3%
U.S. Government & Federal Agencies 4.5%
Asset-Backed Securities 3.6%
Short-Term Investments 2.4%
Foreign Government Bonds 0.6%
Loan Assignments 0.4%
Other Assets, Less Liabilities 1.0%
Largest Holdings [Text Block]
Top Ten Holdings and/or Issuers*
GNMA, (zero coupon)-7.764%, due 7/20/44-2/16/66 3.1%
UMBS, 30 Year, 2.00%-6.50%, due 8/1/48-9/1/54 2.0%
Broadcom, Inc. 1.4%
Microsoft Corp. 1.4%
Connecticut Avenue Securities Trust, 6.053%-14.204%, due 11/25/39-2/25/45 1.4%
AbbVie, Inc. 1.3%
International Business Machines Corp. 1.3%
FHLMC STACR REMIC Trust, 6.004%-11.454%, due 9/25/41-1/25/50 1.3%
Cisco Systems, Inc. 1.2%
Philip Morris International, Inc. 1.2%
* Excluding short-term investments
C000185564 [Member]  
Shareholder Report [Line Items]  
Fund Name NYLI Income Builder Fund
Class Name Class R6
Trading Symbol MTODX
Annual or Semi-Annual Statement [Text Block] This semiannual shareholder report contains important information about NYLI Income Builder Fund (the "Fund") for the period November 1, 2024 to April 30, 2025.
Shareholder Report Annual or Semi-Annual semi-annual shareholder report
Additional Information [Text Block] You can find additional information about the Fund at dfinview.com/NYLIM. You can also request this information by contacting us at 800-624-6782.
Additional Information Phone Number 800-624-6782
Additional Information Website dfinview.com/NYLIM
Expenses [Text Block]
What were the Fund costs for the last six months?
(Based on a hypothetical $10,000 investment)
Share Class Name Costs of a $10,000 investment Costs paid as a percentage
of a $10,000 investment1
Class R6 $34 0.68%
1.
Annualized.
Expenses Paid, Amount $ 34
Expense Ratio, Percent 0.68% [47]
Performance Past Does Not Indicate Future [Text] Keep in mind that the Fund ’s past performance is not a good predictor of how the Fund will perform in the future.
Line Graph [Table Text Block]
Fund Performance
The following graph compares the initial and subsequent account values at the end of each of the most recently completed 10 semiannual reporting periods of the Fund (or for the life of the Fund, if shorter). It assumes a $10,000 initial investment at the beginning of the first fiscal period in an appropriate, broad-based securities market index and other additional indexes, if applicable, for the same period and reflects the deduction of all sales charges, where applicable.
Fund Performance - Growth of 10K
Average Annual Return [Table Text Block]
Average Annual Total Returns for the Period Ended April 30, 2025 Inception
Date		 Six
Months1		 One
Year		 Five
Years		 Since
Inception
Class R6 Shares 2/28/2018 1.20% 12.64% 7.21% 5.76%
MSCI World Index (Net)2 0.93% 12.16% 13.95% 9.71%
Bloomberg U.S. Aggregate Bond Index3 2.57% 8.02% (0.67)% 1.69%
Blended Benchmark Index4 1.64% 10.56% 8.08% 6.71%
Morningstar Global Moderate Allocation Category Average5 (1.07)% 8.64% 7.97% 5.21%
1.
Not annualized.
2.
The Fund has selected the MSCI World Index (Net) to represent a broad measure of market performance. The MSCI World Index (Net) is a free float-adjusted market capitalization weighted index that is designed to measure the equity market performance of developed markets.
3.
The Bloomberg U.S. Aggregate Bond Index is a broad-based benchmark that measures performance of the investment-grade, U.S. dollar-denominated, fixed-rate taxable bond market, including Treasuries, government-related and corporate securities, mortgage-backed securities (agency fixed-rate and hybrid adjustable-rate mortgage pass-throughs), asset-backed securities and commercial mortgage-backed securities.
4.
The Blended Benchmark Index is comprised of the MSCI World Index (Net) and the Bloomberg U.S. Aggregate Bond Index weighted 60%/40%.
5.
Morningstar Global Moderate Allocation Category Average funds seek to provide both income and capital appreciation by primarily investing in multiple asset classes, including stocks, bonds, and cash. These moderate strategies seek to balance preservation of capital with appreciation. They typically expect volatility similar to a strategic equity exposure between 50% and 70%. Results are based on average total returns of similar funds with all dividends and capital gain distributions reinvested.
Performance Inception Date Feb. 28, 2018
No Deduction of Taxes [Text Block] The graph and table do not reflect the deduction of taxes that a shareholder would pay on Fund distributions or redemption of Fund shares.
Updated Performance Information Location [Text Block] Visit newyorklifeinvestments.com/funds for the most recent performance information.
Net Assets $ 1,001,362,966
Holdings Count | Holding 561
Investment Company Portfolio Turnover 19.00%
Additional Fund Statistics [Text Block]
Key Fund Statistics
Fund's net assets $1,001,362,966%
Total number of portfolio holdings 561%
Portfolio turnover rate 19%
Holdings [Text Block]
Graphical Representation of Holdings
The tables below show the investment makeup of the Fund; percentages indicated are based on the Fund's net assets.
Top Ten Holdings and/or Issuers*
GNMA, (zero coupon)-7.764%, due 7/20/44-2/16/66 3.1%
UMBS, 30 Year, 2.00%-6.50%, due 8/1/48-9/1/54 2.0%
Broadcom, Inc. 1.4%
Microsoft Corp. 1.4%
Connecticut Avenue Securities Trust, 6.053%-14.204%, due 11/25/39-2/25/45 1.4%
AbbVie, Inc. 1.3%
International Business Machines Corp. 1.3%
FHLMC STACR REMIC Trust, 6.004%-11.454%, due 9/25/41-1/25/50 1.3%
Cisco Systems, Inc. 1.2%
Philip Morris International, Inc. 1.2%
* Excluding short-term investments
Portfolio Composition 
Common Stocks 62.0%
Mortgage-Backed Securities 13.2%
Corporate Bonds 12.3%
U.S. Government & Federal Agencies 4.5%
Asset-Backed Securities 3.6%
Short-Term Investments 2.4%
Foreign Government Bonds 0.6%
Loan Assignments 0.4%
Other Assets, Less Liabilities 1.0%
Largest Holdings [Text Block]
Top Ten Holdings and/or Issuers*
GNMA, (zero coupon)-7.764%, due 7/20/44-2/16/66 3.1%
UMBS, 30 Year, 2.00%-6.50%, due 8/1/48-9/1/54 2.0%
Broadcom, Inc. 1.4%
Microsoft Corp. 1.4%
Connecticut Avenue Securities Trust, 6.053%-14.204%, due 11/25/39-2/25/45 1.4%
AbbVie, Inc. 1.3%
International Business Machines Corp. 1.3%
FHLMC STACR REMIC Trust, 6.004%-11.454%, due 9/25/41-1/25/50 1.3%
Cisco Systems, Inc. 1.2%
Philip Morris International, Inc. 1.2%
* Excluding short-term investments
C000060796 [Member]  
Shareholder Report [Line Items]  
Fund Name NYLI Income Builder Fund
Class Name Investor Class
Trading Symbol MTINX
Annual or Semi-Annual Statement [Text Block] This semiannual shareholder report contains important information about NYLI Income Builder Fund (the "Fund") for the period November 1, 2024 to April 30, 2025.
Shareholder Report Annual or Semi-Annual semi-annual shareholder report
Additional Information [Text Block] You can find additional information about the Fund at dfinview.com/NYLIM. You can also request this information by contacting us at 800-624-6782.
Additional Information Phone Number 800-624-6782
Additional Information Website dfinview.com/NYLIM
Expenses [Text Block]
What were the Fund costs for the last six months?
(Based on a hypothetical $10,000 investment)
Share Class Name Costs of a $10,000 investment Costs paid as a percentage
of a $10,000 investment1,2
Investor Class $64 1.28%
1.
Reflects fee waivers and/or expense reimbursements, without which expenses would have been higher.
2.
Annualized.
Expenses Paid, Amount $ 64
Expense Ratio, Percent 1.28% [48],[49]
Performance Past Does Not Indicate Future [Text] Keep in mind that the Fund ’s past performance is not a good predictor of how the Fund will perform in the future.
Line Graph [Table Text Block]
Fund Performance
The following graph compares the initial and subsequent account values at the end of each of the most recently completed 10 semiannual reporting periods of the Fund (or for the life of the Fund, if shorter). It assumes a $10,000 initial investment at the beginning of the first fiscal period in an appropriate, broad-based securities market index and other additional indexes, if applicable, for the same period and reflects the deduction of all sales charges, where applicable.
Fund Performance - Growth of 10K
Average Annual Return [Table Text Block]
Average Annual Total Returns for the Period Ended April 30, 2025 Inception
Date		 Six
Months1		 One
Year		 Five
Years		 Ten
Years
Investor Class Shares - Including sales charges 2/28/2008 (1.61)% 9.22% 5.97% 4.18%
Investor Class Shares - Excluding sales charges 0.91% 12.02% 6.62% 4.77%
MSCI World Index (Net)2 0.93% 12.16% 13.95% 9.34%
Bloomberg U.S. Aggregate Bond Index3 2.57% 8.02% (0.67)% 1.54%
Blended Benchmark Index4 1.64% 10.56% 8.08% 6.40%
Morningstar Global Moderate Allocation Category Average5 (1.07)% 8.64% 7.97% 4.90%
1.
Not annualized.
2.
The Fund has selected the MSCI World Index (Net) to represent a broad measure of market performance. The MSCI World Index (Net) is a free float-adjusted market capitalization weighted index that is designed to measure the equity market performance of developed markets.
3.
The Bloomberg U.S. Aggregate Bond Index is a broad-based benchmark that measures performance of the investment-grade, U.S. dollar-denominated, fixed-rate taxable bond market, including Treasuries, government-related and corporate securities, mortgage-backed securities (agency fixed-rate and hybrid adjustable-rate mortgage pass-throughs), asset-backed securities and commercial mortgage-backed securities.
4.
The Blended Benchmark Index is comprised of the MSCI World Index (Net) and the Bloomberg U.S. Aggregate Bond Index weighted 60%/40%.
5.
Morningstar Global Moderate Allocation Category Average funds seek to provide both income and capital appreciation by primarily investing in multiple asset classes, including stocks, bonds, and cash. These moderate strategies seek to balance preservation of capital with appreciation. They typically expect volatility similar to a strategic equity exposure between 50% and 70%. Results are based on average total returns of similar funds with all dividends and capital gain distributions reinvested.
Performance Inception Date Feb. 28, 2008
No Deduction of Taxes [Text Block] The graph and table do not reflect the deduction of taxes that a shareholder would pay on Fund distributions or redemption of Fund shares.
Updated Performance Information Location [Text Block] Visit newyorklifeinvestments.com/funds for the most recent performance information.
Net Assets $ 1,001,362,966
Holdings Count | Holding 561
Investment Company Portfolio Turnover 19.00%
Additional Fund Statistics [Text Block]
Key Fund Statistics
Fund's net assets $1,001,362,966%
Total number of portfolio holdings 561%
Portfolio turnover rate 19%
Holdings [Text Block]
Graphical Representation of Holdings
The tables below show the investment makeup of the Fund; percentages indicated are based on the Fund's net assets.
Top Ten Holdings and/or Issuers*
GNMA, (zero coupon)-7.764%, due 7/20/44-2/16/66 3.1%
UMBS, 30 Year, 2.00%-6.50%, due 8/1/48-9/1/54 2.0%
Broadcom, Inc. 1.4%
Microsoft Corp. 1.4%
Connecticut Avenue Securities Trust, 6.053%-14.204%, due 11/25/39-2/25/45 1.4%
AbbVie, Inc. 1.3%
International Business Machines Corp. 1.3%
FHLMC STACR REMIC Trust, 6.004%-11.454%, due 9/25/41-1/25/50 1.3%
Cisco Systems, Inc. 1.2%
Philip Morris International, Inc. 1.2%
* Excluding short-term investments
Portfolio Composition 
Common Stocks 62.0%
Mortgage-Backed Securities 13.2%
Corporate Bonds 12.3%
U.S. Government & Federal Agencies 4.5%
Asset-Backed Securities 3.6%
Short-Term Investments 2.4%
Foreign Government Bonds 0.6%
Loan Assignments 0.4%
Other Assets, Less Liabilities 1.0%
Largest Holdings [Text Block]
Top Ten Holdings and/or Issuers*
GNMA, (zero coupon)-7.764%, due 7/20/44-2/16/66 3.1%
UMBS, 30 Year, 2.00%-6.50%, due 8/1/48-9/1/54 2.0%
Broadcom, Inc. 1.4%
Microsoft Corp. 1.4%
Connecticut Avenue Securities Trust, 6.053%-14.204%, due 11/25/39-2/25/45 1.4%
AbbVie, Inc. 1.3%
International Business Machines Corp. 1.3%
FHLMC STACR REMIC Trust, 6.004%-11.454%, due 9/25/41-1/25/50 1.3%
Cisco Systems, Inc. 1.2%
Philip Morris International, Inc. 1.2%
* Excluding short-term investments
C000221696 [Member]  
Shareholder Report [Line Items]  
Fund Name NYLI Income Builder Fund
Class Name SIMPLE Class
Trading Symbol MTISX
Annual or Semi-Annual Statement [Text Block] This semiannual shareholder report contains important information about NYLI Income Builder Fund (the "Fund") for the period November 1, 2024 to April 30, 2025.
Shareholder Report Annual or Semi-Annual semi-annual shareholder report
Additional Information [Text Block] You can find additional information about the Fund at dfinview.com/NYLIM. You can also request this information by contacting us at 800-624-6782.
Additional Information Phone Number 800-624-6782
Additional Information Website dfinview.com/NYLIM
Expenses [Text Block]
What were the Fund costs for the last six months?
(Based on a hypothetical $10,000 investment)
Share Class Name Costs of a $10,000 investment Costs paid as a percentage
of a $10,000 investment1
SIMPLE Class $63 1.26%
1.
Annualized.
Expenses Paid, Amount $ 63
Expense Ratio, Percent 1.26% [50]
Performance Past Does Not Indicate Future [Text] Keep in mind that the Fund ’s past performance is not a good predictor of how the Fund will perform in the future.
Line Graph [Table Text Block]
Fund Performance
The following graph compares the initial and subsequent account values at the end of each of the most recently completed 10 semiannual reporting periods of the Fund (or for the life of the Fund, if shorter). It assumes a $10,000 initial investment at the beginning of the first fiscal period in an appropriate, broad-based securities market index and other additional indexes, if applicable, for the same period and reflects the deduction of all sales charges, where applicable.
Fund Performance - Growth of 10K
Average Annual Return [Table Text Block]
Average Annual Total Returns for the Period Ended April 30, 2025 Inception
Date		 Six
Months1		 One
Year		 Since
Inception
SIMPLE Class Shares 8/31/2020 0.97% 12.02% 4.88%
MSCI World Index (Net)2 0.93% 12.16% 10.55%
Bloomberg U.S. Aggregate Bond Index3 2.57% 8.02% (1.09)%
Blended Benchmark Index4 1.64% 10.56% 5.94%
Morningstar Global Moderate Allocation Category Average5 (1.07)% 8.64% 5.83%
1.
Not annualized.
2.
The Fund has selected the MSCI World Index (Net) to represent a broad measure of market performance. The MSCI World Index (Net) is a free float-adjusted market capitalization weighted index that is designed to measure the equity market performance of developed markets.
3.
The Bloomberg U.S. Aggregate Bond Index is a broad-based benchmark that measures performance of the investment-grade, U.S. dollar-denominated, fixed-rate taxable bond market, including Treasuries, government-related and corporate securities, mortgage-backed securities (agency fixed-rate and hybrid adjustable-rate mortgage pass-throughs), asset-backed securities and commercial mortgage-backed securities.
4.
The Blended Benchmark Index is comprised of the MSCI World Index (Net) and the Bloomberg U.S. Aggregate Bond Index weighted 60%/40%.
5.
Morningstar Global Moderate Allocation Category Average funds seek to provide both income and capital appreciation by primarily investing in multiple asset classes, including stocks, bonds, and cash. These moderate strategies seek to balance preservation of capital with appreciation. They typically expect volatility similar to a strategic equity exposure between 50% and 70%. Results are based on average total returns of similar funds with all dividends and capital gain distributions reinvested.
Performance Inception Date Aug. 31, 2020
No Deduction of Taxes [Text Block] The graph and table do not reflect the deduction of taxes that a shareholder would pay on Fund distributions or redemption of Fund shares.
Updated Performance Information Location [Text Block] Visit newyorklifeinvestments.com/funds for the most recent performance information.
Net Assets $ 1,001,362,966
Holdings Count | Holding 561
Investment Company Portfolio Turnover 19.00%
Additional Fund Statistics [Text Block]
Key Fund Statistics
Fund's net assets $1,001,362,966%
Total number of portfolio holdings 561%
Portfolio turnover rate 19%
Holdings [Text Block]
Graphical Representation of Holdings
The tables below show the investment makeup of the Fund; percentages indicated are based on the Fund's net assets.
Top Ten Holdings and/or Issuers*
GNMA, (zero coupon)-7.764%, due 7/20/44-2/16/66 3.1%
UMBS, 30 Year, 2.00%-6.50%, due 8/1/48-9/1/54 2.0%
Broadcom, Inc. 1.4%
Microsoft Corp. 1.4%
Connecticut Avenue Securities Trust, 6.053%-14.204%, due 11/25/39-2/25/45 1.4%
AbbVie, Inc. 1.3%
International Business Machines Corp. 1.3%
FHLMC STACR REMIC Trust, 6.004%-11.454%, due 9/25/41-1/25/50 1.3%
Cisco Systems, Inc. 1.2%
Philip Morris International, Inc. 1.2%
* Excluding short-term investments
Portfolio Composition 
Common Stocks 62.0%
Mortgage-Backed Securities 13.2%
Corporate Bonds 12.3%
U.S. Government & Federal Agencies 4.5%
Asset-Backed Securities 3.6%
Short-Term Investments 2.4%
Foreign Government Bonds 0.6%
Loan Assignments 0.4%
Other Assets, Less Liabilities 1.0%
Largest Holdings [Text Block]
Top Ten Holdings and/or Issuers*
GNMA, (zero coupon)-7.764%, due 7/20/44-2/16/66 3.1%
UMBS, 30 Year, 2.00%-6.50%, due 8/1/48-9/1/54 2.0%
Broadcom, Inc. 1.4%
Microsoft Corp. 1.4%
Connecticut Avenue Securities Trust, 6.053%-14.204%, due 11/25/39-2/25/45 1.4%
AbbVie, Inc. 1.3%
International Business Machines Corp. 1.3%
FHLMC STACR REMIC Trust, 6.004%-11.454%, due 9/25/41-1/25/50 1.3%
Cisco Systems, Inc. 1.2%
Philip Morris International, Inc. 1.2%
* Excluding short-term investments
C000018710 [Member]  
Shareholder Report [Line Items]  
Fund Name NYLI Candriam Emerging Markets Debt Fund
Class Name Class A
Trading Symbol MGHAX
Annual or Semi-Annual Statement [Text Block] This semiannual shareholder report contains important information about NYLI Candriam Emerging Markets Debt Fund (the "Fund") for the period November 1, 2024 to April 30, 2025.
Shareholder Report Annual or Semi-Annual semi-annual shareholder report
Additional Information [Text Block] You can find additional information about the Fund at dfinview.com/NYLIM. You can also request this information by contacting us at 800-624-6782.
Additional Information Phone Number 800-624-6782
Additional Information Website dfinview.com/NYLIM
Expenses [Text Block]
What were the Fund costs for the last six months?
(Based on a hypothetical $10,000 investment)
Share Class Name Costs of a $10,000 investment Costs paid as a percentage
of a $10,000 investment1,2
Class A $57 1.15%
1.
Reflects fee waivers and/or expense reimbursements, without which expenses would have been higher.
2.
Annualized.
Expenses Paid, Amount $ 57
Expense Ratio, Percent 1.15% [51],[52]
Performance Past Does Not Indicate Future [Text] Keep in mind that the Fund ’s past performance is not a good predictor of how the Fund will perform in the future.
Line Graph [Table Text Block]
Fund Performance
The following graph compares the initial and subsequent account values at the end of each of the most recently completed 10 semiannual reporting periods of the Fund (or for the life of the Fund, if shorter). It assumes a $15,000 initial investment at the beginning of the first fiscal period in an appropriate, broad-based securities market index and other additional indexes, if applicable, for the same period and reflects the deduction of all sales charges, where applicable. 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 graph and table prior to those dates reflects the Fund’s prior subadvisor, investment objective and principal investment strategies.
Fund Performance - Growth of 10K
Average Annual Return [Table Text Block]
Average Annual Total Returns for the Period Ended April 30, 2025 Inception
Date		 Six
Months1		 One
Year		 Five
Years		 Ten
Years
Class A Shares - Including sales charges 6/1/1998 (4.23)% 1.71% 2.63% 2.16%
Class A Shares - Excluding sales charges 0.29% 6.50% 3.58% 2.63%
JPMorgan EMBI Global Diversified Index2 1.79% 8.77% 2.99% 2.97%
Morningstar Emerging Markets Bond Category Average3 1.94% 8.43% 3.97% 2.82%
1.
Not annualized.
2.
The Fund has selected the JPMorgan EMBI Global Diversified Index to represent a broad measure of market performance. 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.
3.
The Morningstar Emerging Markets Bond Category Average is representative of funds that invest more than 65% of their assets in foreign bonds from developing countries. The largest portion of the emerging-markets bond market comes from Latin America, followed by Eastern Europe. Africa, the Middle East, and Asia make up the rest. Results are based on average total returns of similar funds with all dividends and capital gain distributions reinvested.
Performance Inception Date Jun. 01, 1998
No Deduction of Taxes [Text Block] The graph and table do not reflect the deduction of taxes that a shareholder would pay on Fund distributions or redemption of Fund shares.
Updated Performance Information Location [Text Block] Visit newyorklifeinvestments.com/funds for the most recent performance information.
Net Assets $ 128,391,878
Holdings Count | Holding 141
Investment Company Portfolio Turnover 46.00%
Additional Fund Statistics [Text Block]
Key Fund Statistics
Fund's net assets $128,391,878%
Total number of portfolio holdings 141%
Portfolio turnover rate 46%
Holdings [Text Block]
Graphical Representation of Holdings
The tables below show the investment makeup of the Fund; percentages indicated are based on the Fund's net assets.
Top Ten Holdings and/or Issuers*
Brazil Government Bond, 3.875%-7.125%, due 6/12/30-5/13/54 5.7%
Colombia Government Bond, 5.00%-8.75%, due 4/20/33-11/14/53 5.1%
Mexico Government Bond, 3.50%-6.00%, due 5/19/33-10/12/2110 4.7%
Dominican Republic Government Bond, 4.875%-7.05%, due 2/22/29-1/30/60 4.4%
Hungary Government Bond, 2.125%-7.625%, due 6/16/29-3/29/41 4.3%
Poland Government Bond, 5.375%-5.50%, due 2/12/35-3/18/54 3.7%
Turkey Government Bond, 4.875%-5.75%, due 3/13/30-5/11/47 3.1%
Egypt Government Bond, 7.625%-8.875%, due 5/29/32-5/29/50 3.1%
Argentina Government Bond, 0.75%-3.50%, due 7/9/29-7/9/41 2.9%
Oman Government Bond, 6.00%-6.75%, due 8/1/29-1/17/48 2.8%
* Excluding short-term investments
Top Countries
Colombia 6.8%
Brazil 5.7%
Turkey 5.3%
Hungary 5.0%
Poland 5.0%
Mexico 4.7%
Dominican Republic 4.4%
Egypt 3.1%
United States 3.0%
Argentina 2.9%
Largest Holdings [Text Block]
Top Ten Holdings and/or Issuers*
Brazil Government Bond, 3.875%-7.125%, due 6/12/30-5/13/54 5.7%
Colombia Government Bond, 5.00%-8.75%, due 4/20/33-11/14/53 5.1%
Mexico Government Bond, 3.50%-6.00%, due 5/19/33-10/12/2110 4.7%
Dominican Republic Government Bond, 4.875%-7.05%, due 2/22/29-1/30/60 4.4%
Hungary Government Bond, 2.125%-7.625%, due 6/16/29-3/29/41 4.3%
Poland Government Bond, 5.375%-5.50%, due 2/12/35-3/18/54 3.7%
Turkey Government Bond, 4.875%-5.75%, due 3/13/30-5/11/47 3.1%
Egypt Government Bond, 7.625%-8.875%, due 5/29/32-5/29/50 3.1%
Argentina Government Bond, 0.75%-3.50%, due 7/9/29-7/9/41 2.9%
Oman Government Bond, 6.00%-6.75%, due 8/1/29-1/17/48 2.8%
* Excluding short-term investments
C000018712 [Member]  
Shareholder Report [Line Items]  
Fund Name NYLI Candriam Emerging Markets Debt Fund
Class Name Class C
Trading Symbol MHYCX
Annual or Semi-Annual Statement [Text Block] This semiannual shareholder report contains important information about NYLI Candriam Emerging Markets Debt Fund (the "Fund") for the period November 1, 2024 to April 30, 2025.
Shareholder Report Annual or Semi-Annual semi-annual shareholder report
Additional Information [Text Block] You can find additional information about the Fund at dfinview.com/NYLIM. You can also request this information by contacting us at 800-624-6782.
Additional Information Phone Number 800-624-6782
Additional Information Website dfinview.com/NYLIM
Expenses [Text Block]
What were the Fund costs for the last six months?
(Based on a hypothetical $10,000 investment)
Share Class Name Costs of a $10,000 investment Costs paid as a percentage
of a $10,000 investment1,2
Class C $114 2.29%
1.
Reflects fee waivers and/or expense reimbursements, without which expenses would have been higher.
2.
Annualized.
Expenses Paid, Amount $ 114
Expense Ratio, Percent 2.29% [53],[54]
Performance Past Does Not Indicate Future [Text] Keep in mind that the Fund ’s past performance is not a good predictor of how the Fund will perform in the future.
Line Graph [Table Text Block]
Fund Performance
The following graph compares the initial and subsequent account values at the end of each of the most recently completed 10 semiannual reporting periods of the Fund (or for the life of the Fund, if shorter). It assumes a $10,000 initial investment at the beginning of the first fiscal period in an appropriate, broad-based securities market index and other additional indexes, if applicable, for the same period and reflects the deduction of all sales charges, where applicable. 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 graph and table prior to those dates reflects the Fund’s prior subadvisor, investment objective and principal investment strategies.
Fund Performance - Growth of 10K
Average Annual Return [Table Text Block]
Average Annual Total Returns for the Period Ended April 30, 2025 Inception
Date		 Six
Months1		 One
Year		 Five
Years		 Ten
Years
Class C Shares - Including sales charges 9/1/1998 (1.11)% 4.29% 2.38% 1.54%
Class C Shares - Excluding sales charges (0.15)% 5.28% 2.38% 1.54%
JPMorgan EMBI Global Diversified Index2 1.79% 8.77% 2.99% 2.97%
Morningstar Emerging Markets Bond Category Average3 1.94% 8.43% 3.97% 2.82%
1.
Not annualized.
2.
The Fund has selected the JPMorgan EMBI Global Diversified Index to represent a broad measure of market performance. 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.
3.
The Morningstar Emerging Markets Bond Category Average is representative of funds that invest more than 65% of their assets in foreign bonds from developing countries. The largest portion of the emerging-markets bond market comes from Latin America, followed by Eastern Europe. Africa, the Middle East, and Asia make up the rest. Results are based on average total returns of similar funds with all dividends and capital gain distributions reinvested.
Performance Inception Date Sep. 01, 1998
No Deduction of Taxes [Text Block] The graph and table do not reflect the deduction of taxes that a shareholder would pay on Fund distributions or redemption of Fund shares.
Updated Performance Information Location [Text Block] Visit newyorklifeinvestments.com/funds for the most recent performance information.
Net Assets $ 128,391,878
Holdings Count | Holding 141
Investment Company Portfolio Turnover 46.00%
Additional Fund Statistics [Text Block]
Key Fund Statistics
Fund's net assets $128,391,878%
Total number of portfolio holdings 141%
Portfolio turnover rate 46%
Holdings [Text Block]
Graphical Representation of Holdings
The tables below show the investment makeup of the Fund; percentages indicated are based on the Fund's net assets.
Top Ten Holdings and/or Issuers*
Brazil Government Bond, 3.875%-7.125%, due 6/12/30-5/13/54 5.7%
Colombia Government Bond, 5.00%-8.75%, due 4/20/33-11/14/53 5.1%
Mexico Government Bond, 3.50%-6.00%, due 5/19/33-10/12/2110 4.7%
Dominican Republic Government Bond, 4.875%-7.05%, due 2/22/29-1/30/60 4.4%
Hungary Government Bond, 2.125%-7.625%, due 6/16/29-3/29/41 4.3%
Poland Government Bond, 5.375%-5.50%, due 2/12/35-3/18/54 3.7%
Turkey Government Bond, 4.875%-5.75%, due 3/13/30-5/11/47 3.1%
Egypt Government Bond, 7.625%-8.875%, due 5/29/32-5/29/50 3.1%
Argentina Government Bond, 0.75%-3.50%, due 7/9/29-7/9/41 2.9%
Oman Government Bond, 6.00%-6.75%, due 8/1/29-1/17/48 2.8%
* Excluding short-term investments
Top Countries
Colombia 6.8%
Brazil 5.7%
Turkey 5.3%
Hungary 5.0%
Poland 5.0%
Mexico 4.7%
Dominican Republic 4.4%
Egypt 3.1%
United States 3.0%
Argentina 2.9%
Largest Holdings [Text Block]
Top Ten Holdings and/or Issuers*
Brazil Government Bond, 3.875%-7.125%, due 6/12/30-5/13/54 5.7%
Colombia Government Bond, 5.00%-8.75%, due 4/20/33-11/14/53 5.1%
Mexico Government Bond, 3.50%-6.00%, due 5/19/33-10/12/2110 4.7%
Dominican Republic Government Bond, 4.875%-7.05%, due 2/22/29-1/30/60 4.4%
Hungary Government Bond, 2.125%-7.625%, due 6/16/29-3/29/41 4.3%
Poland Government Bond, 5.375%-5.50%, due 2/12/35-3/18/54 3.7%
Turkey Government Bond, 4.875%-5.75%, due 3/13/30-5/11/47 3.1%
Egypt Government Bond, 7.625%-8.875%, due 5/29/32-5/29/50 3.1%
Argentina Government Bond, 0.75%-3.50%, due 7/9/29-7/9/41 2.9%
Oman Government Bond, 6.00%-6.75%, due 8/1/29-1/17/48 2.8%
* Excluding short-term investments
C000052120 [Member]  
Shareholder Report [Line Items]  
Fund Name NYLI Candriam Emerging Markets Debt Fund
Class Name Class I
Trading Symbol MGHIX
Annual or Semi-Annual Statement [Text Block] This semiannual shareholder report contains important information about NYLI Candriam Emerging Markets Debt Fund (the "Fund") for the period November 1, 2024 to April 30, 2025.
Shareholder Report Annual or Semi-Annual semi-annual shareholder report
Additional Information [Text Block] You can find additional information about the Fund at dfinview.com/NYLIM. You can also request this information by contacting us at 800-624-6782.
Additional Information Phone Number 800-624-6782
Additional Information Website dfinview.com/NYLIM
Expenses [Text Block]
What were the Fund costs for the last six months?
(Based on a hypothetical $10,000 investment)
Share Class Name Costs of a $10,000 investment Costs paid as a percentage
of a $10,000 investment1,2
Class I $42 0.85%
1.
Reflects fee waivers and/or expense reimbursements, without which expenses would have been higher.
2.
Annualized.
Expenses Paid, Amount $ 42
Expense Ratio, Percent 0.85% [55],[56]
Performance Past Does Not Indicate Future [Text] Keep in mind that the Fund ’s past performance is not a good predictor of how the Fund will perform in the future.
Line Graph [Table Text Block]
Fund Performance
The following graph compares the initial and subsequent account values at the end of each of the most recently completed 10 semiannual reporting periods of the Fund (or for the life of the Fund, if shorter). It assumes a $10,000 initial investment at the beginning of the first fiscal period in an appropriate, broad-based securities market index and other additional indexes, if applicable, for the same period and reflects the deduction of all sales charges, where applicable. 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 graph and table prior to those dates reflects the Fund’s prior subadvisor, investment objective and principal investment strategies.
Fund Performance - Growth of 10K
Average Annual Return [Table Text Block]
Average Annual Total Returns for the Period Ended April 30, 2025 Inception
Date		 Six
Months1		 One
Year		 Five
Years		 Ten
Years
Class I Shares 8/31/2007 0.43% 6.80% 3.88% 2.91%
JPMorgan EMBI Global Diversified Index2 1.79% 8.77% 2.99% 2.97%
Morningstar Emerging Markets Bond Category Average3 1.94% 8.43% 3.97% 2.82%
1.
Not annualized.
2.
The Fund has selected the JPMorgan EMBI Global Diversified Index to represent a broad measure of market performance. 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.
3.
The Morningstar Emerging Markets Bond Category Average is representative of funds that invest more than 65% of their assets in foreign bonds from developing countries. The largest portion of the emerging-markets bond market comes from Latin America, followed by Eastern Europe. Africa, the Middle East, and Asia make up the rest. Results are based on average total returns of similar funds with all dividends and capital gain distributions reinvested.
Performance Inception Date Aug. 31, 2007
No Deduction of Taxes [Text Block] The graph and table do not reflect the deduction of taxes that a shareholder would pay on Fund distributions or redemption of Fund shares.
Updated Performance Information Location [Text Block] Visit newyorklifeinvestments.com/funds for the most recent performance information.
Net Assets $ 128,391,878
Holdings Count | Holding 141
Investment Company Portfolio Turnover 46.00%
Additional Fund Statistics [Text Block]
Key Fund Statistics
Fund's net assets $128,391,878%
Total number of portfolio holdings 141%
Portfolio turnover rate 46%
Holdings [Text Block]
Graphical Representation of Holdings
The tables below show the investment makeup of the Fund; percentages indicated are based on the Fund's net assets.
Top Ten Holdings and/or Issuers*
Brazil Government Bond, 3.875%-7.125%, due 6/12/30-5/13/54 5.7%
Colombia Government Bond, 5.00%-8.75%, due 4/20/33-11/14/53 5.1%
Mexico Government Bond, 3.50%-6.00%, due 5/19/33-10/12/2110 4.7%
Dominican Republic Government Bond, 4.875%-7.05%, due 2/22/29-1/30/60 4.4%
Hungary Government Bond, 2.125%-7.625%, due 6/16/29-3/29/41 4.3%
Poland Government Bond, 5.375%-5.50%, due 2/12/35-3/18/54 3.7%
Turkey Government Bond, 4.875%-5.75%, due 3/13/30-5/11/47 3.1%
Egypt Government Bond, 7.625%-8.875%, due 5/29/32-5/29/50 3.1%
Argentina Government Bond, 0.75%-3.50%, due 7/9/29-7/9/41 2.9%
Oman Government Bond, 6.00%-6.75%, due 8/1/29-1/17/48 2.8%
* Excluding short-term investments
Top Countries
Colombia 6.8%
Brazil 5.7%
Turkey 5.3%
Hungary 5.0%
Poland 5.0%
Mexico 4.7%
Dominican Republic 4.4%
Egypt 3.1%
United States 3.0%
Argentina 2.9%
Largest Holdings [Text Block]
Top Ten Holdings and/or Issuers*
Brazil Government Bond, 3.875%-7.125%, due 6/12/30-5/13/54 5.7%
Colombia Government Bond, 5.00%-8.75%, due 4/20/33-11/14/53 5.1%
Mexico Government Bond, 3.50%-6.00%, due 5/19/33-10/12/2110 4.7%
Dominican Republic Government Bond, 4.875%-7.05%, due 2/22/29-1/30/60 4.4%
Hungary Government Bond, 2.125%-7.625%, due 6/16/29-3/29/41 4.3%
Poland Government Bond, 5.375%-5.50%, due 2/12/35-3/18/54 3.7%
Turkey Government Bond, 4.875%-5.75%, due 3/13/30-5/11/47 3.1%
Egypt Government Bond, 7.625%-8.875%, due 5/29/32-5/29/50 3.1%
Argentina Government Bond, 0.75%-3.50%, due 7/9/29-7/9/41 2.9%
Oman Government Bond, 6.00%-6.75%, due 8/1/29-1/17/48 2.8%
* Excluding short-term investments
C000060797 [Member]  
Shareholder Report [Line Items]  
Fund Name NYLI Candriam Emerging Markets Debt Fund
Class Name Investor Class
Trading Symbol MGHHX
Annual or Semi-Annual Statement [Text Block] This semiannual shareholder report contains important information about NYLI Candriam Emerging Markets Debt Fund (the "Fund") for the period November 1, 2024 to April 30, 2025.
Shareholder Report Annual or Semi-Annual semi-annual shareholder report
Additional Information [Text Block] You can find additional information about the Fund at dfinview.com/NYLIM. You can also request this information by contacting us at 800-624-6782.
Additional Information Phone Number 800-624-6782
Additional Information Website dfinview.com/NYLIM
Expenses [Text Block]
What were the Fund costs for the last six months?
(Based on a hypothetical $10,000 investment)
Share Class Name Costs of a $10,000 investment Costs paid as a percentage
of a $10,000 investment1,2
Investor Class $76 1.54%
1.
Reflects fee waivers and/or expense reimbursements, without which expenses would have been higher.
2.
Annualized.
Expenses Paid, Amount $ 76
Expense Ratio, Percent 1.54% [57],[58]
Performance Past Does Not Indicate Future [Text] Keep in mind that the Fund ’s past performance is not a good predictor of how the Fund will perform in the future.
Line Graph [Table Text Block]
Fund Performance
The following graph compares the initial and subsequent account values at the end of each of the most recently completed 10 semiannual reporting periods of the Fund (or for the life of the Fund, if shorter). It assumes a $10,000 initial investment at the beginning of the first fiscal period in an appropriate, broad-based securities market index and other additional indexes, if applicable, for the same period and reflects the deduction of all sales charges, where applicable. 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 graph and table prior to those dates reflects the Fund’s prior subadvisor, investment objective and principal investment strategies.
Fund Performance - Growth of 10K
Average Annual Return [Table Text Block]
Average Annual Total Returns for the Period Ended April 30, 2025 Inception
Date		 Six
Months1		 One
Year		 Five
Years		 Ten
Years
Investor Class Shares - Including sales charges 2/28/2008 (3.79)% 1.87% 2.22% 1.84%
Investor Class Shares - Excluding sales charges 0.21% 6.11% 3.17% 2.31%
JPMorgan EMBI Global Diversified Index2 1.79% 8.77% 2.99% 2.97%
Morningstar Emerging Markets Bond Category Average3 1.94% 8.43% 3.97% 2.82%
1.
Not annualized.
2.
The Fund has selected the JPMorgan EMBI Global Diversified Index to represent a broad measure of market performance. 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.
3.
The Morningstar Emerging Markets Bond Category Average is representative of funds that invest more than 65% of their assets in foreign bonds from developing countries. The largest portion of the emerging-markets bond market comes from Latin America, followed by Eastern Europe. Africa, the Middle East, and Asia make up the rest. Results are based on average total returns of similar funds with all dividends and capital gain distributions reinvested.
Performance Inception Date Feb. 28, 2008
No Deduction of Taxes [Text Block] The graph and table do not reflect the deduction of taxes that a shareholder would pay on Fund distributions or redemption of Fund shares.
Updated Performance Information Location [Text Block] Visit newyorklifeinvestments.com/funds for the most recent performance information.
Net Assets $ 128,391,878
Holdings Count | Holding 141
Investment Company Portfolio Turnover 46.00%
Additional Fund Statistics [Text Block]
Key Fund Statistics
Fund's net assets $128,391,878%
Total number of portfolio holdings 141%
Portfolio turnover rate 46%
Holdings [Text Block]
Graphical Representation of Holdings
The tables below show the investment makeup of the Fund; percentages indicated are based on the Fund's net assets.
Top Ten Holdings and/or Issuers*
Brazil Government Bond, 3.875%-7.125%, due 6/12/30-5/13/54 5.7%
Colombia Government Bond, 5.00%-8.75%, due 4/20/33-11/14/53 5.1%
Mexico Government Bond, 3.50%-6.00%, due 5/19/33-10/12/2110 4.7%
Dominican Republic Government Bond, 4.875%-7.05%, due 2/22/29-1/30/60 4.4%
Hungary Government Bond, 2.125%-7.625%, due 6/16/29-3/29/41 4.3%
Poland Government Bond, 5.375%-5.50%, due 2/12/35-3/18/54 3.7%
Turkey Government Bond, 4.875%-5.75%, due 3/13/30-5/11/47 3.1%
Egypt Government Bond, 7.625%-8.875%, due 5/29/32-5/29/50 3.1%
Argentina Government Bond, 0.75%-3.50%, due 7/9/29-7/9/41 2.9%
Oman Government Bond, 6.00%-6.75%, due 8/1/29-1/17/48 2.8%
* Excluding short-term investments
Top Countries
Colombia 6.8%
Brazil 5.7%
Turkey 5.3%
Hungary 5.0%
Poland 5.0%
Mexico 4.7%
Dominican Republic 4.4%
Egypt 3.1%
United States 3.0%
Argentina 2.9%
Largest Holdings [Text Block]
Top Ten Holdings and/or Issuers*
Brazil Government Bond, 3.875%-7.125%, due 6/12/30-5/13/54 5.7%
Colombia Government Bond, 5.00%-8.75%, due 4/20/33-11/14/53 5.1%
Mexico Government Bond, 3.50%-6.00%, due 5/19/33-10/12/2110 4.7%
Dominican Republic Government Bond, 4.875%-7.05%, due 2/22/29-1/30/60 4.4%
Hungary Government Bond, 2.125%-7.625%, due 6/16/29-3/29/41 4.3%
Poland Government Bond, 5.375%-5.50%, due 2/12/35-3/18/54 3.7%
Turkey Government Bond, 4.875%-5.75%, due 3/13/30-5/11/47 3.1%
Egypt Government Bond, 7.625%-8.875%, due 5/29/32-5/29/50 3.1%
Argentina Government Bond, 0.75%-3.50%, due 7/9/29-7/9/41 2.9%
Oman Government Bond, 6.00%-6.75%, due 8/1/29-1/17/48 2.8%
* Excluding short-term investments
C000018719 [Member]  
Shareholder Report [Line Items]  
Fund Name NYLI WMC Enduring Capital Fund
Class Name Class A
Trading Symbol MSOAX
Annual or Semi-Annual Statement [Text Block] This semiannual shareholder report contains important information about NYLI WMC Enduring Capital Fund (the "Fund") for the period November 1, 2024 to April 30, 2025.
Shareholder Report Annual or Semi-Annual semi-annual shareholder report
Additional Information [Text Block] You can find additional information about the Fund at dfinview.com/NYLIM. You can also request this information by contacting us at 800-624-6782.
Additional Information Phone Number 800-624-6782
Additional Information Website dfinview.com/NYLIM
Expenses [Text Block]
What were the Fund costs for the last six months?
(Based on a hypothetical $10,000 investment)
Share Class Name Costs of a $10,000 investment Costs paid as a percentage
of a $10,000 investment1
Class A $46 0.92%
1.
Annualized.
Expenses Paid, Amount $ 46
Expense Ratio, Percent 0.92% [59]
Performance Past Does Not Indicate Future [Text] Keep in mind that the Fund ’s past performance is not a good predictor of how the Fund will perform in the future.
Line Graph [Table Text Block]
Fund Performance
The following graph compares the initial and subsequent account values at the end of each of the most recently completed 10 semiannual reporting periods of the Fund (or for the life of the Fund, if shorter). It assumes a $15,000 initial investment at the beginning of the first fiscal period in an appropriate, broad-based securities market index and other additional indexes, if applicable, for the same period and reflects the deduction of all sales charges, where applicable.
Fund Performance - Growth of 10K
Average Annual Return [Table Text Block]
Average Annual Total Returns for the Period Ended April 30, 2025 Inception
Date		 Six
Months1		 One
Year		 Five
Years		 Ten
Years
Class A Shares - Including sales charges 6/1/1998 (3.38)% 5.12% 13.94% 10.24%
Class A Shares - Excluding sales charges 2.24% 11.24% 15.24% 10.87%
Russell 3000®Index2 (2.15)% 11.40% 15.12% 11.68%
S&P 500®Index3 (1.74)% 12.10% 15.61% 12.32%
Morningstar Large Blend Category Average4 (2.35)% 9.59% 14.37% 10.85%
1.
Not annualized.
2.
The Fund has selected the Russell 3000® Index to represent a broad measure of market performance. The Russell 3000® Index measures the performance of the largest 3,000 U.S. companies representing approximately 98% of the investable U.S. equity market.
3.
The S&P 500® Index, which represents a broad measure of market performance, is generally representative of the market sectors or types of investments in which the Fund invests. S&P® and S&P 500® are registered trademarks of Standard & Poor’s Financial Services LLC. The S&P 500® Index is widely regarded as the standard index for measuring large-cap U.S. stock market performance.
4.
The Morningstar Large Blend Category Average is representative of funds that represent the overall U.S. stock market in size, growth rates and price. Stocks in the top 70% of the capitalization of the U.S. equity market are defined as large cap. The blend style is assigned to funds where neither growth nor value characteristics predominate. These funds tend to invest across the spectrum of U.S. industries, and owing to their broad exposure, the funds' returns are often similar to those of the S&P 500® Index. Results are based on average total returns of similar funds with all dividends and capital gain distributions reinvested.
Performance Inception Date Jun. 01, 1998
No Deduction of Taxes [Text Block] The graph and table do not reflect the deduction of taxes that a shareholder would pay on Fund distributions or redemption of Fund shares.
Updated Performance Information Location [Text Block] Visit newyorklifeinvestments.com/funds for the most recent performance information.
Net Assets $ 516,187,803
Holdings Count | Holding 34
Investment Company Portfolio Turnover 7.00%
Additional Fund Statistics [Text Block]
Key Fund Statistics
Fund's net assets $516,187,803%
Total number of portfolio holdings 34%
Portfolio turnover rate 7%
Holdings [Text Block]
Graphical Representation of Holdings
The tables below show the investment makeup of the Fund; percentages indicated are based on the Fund's net assets.
Top Ten Holdings and/or Issuers*
Constellation Software, Inc. 9.2%
Progressive Corp. (The) 6.7%
NVR, Inc. 5.4%
Copart, Inc. 4.9%
Markel Group, Inc. 4.8%
Berkshire Hathaway, Inc., Class B 4.3%
Linde plc 4.1%
Cintas Corp. 4.0%
PACCAR, Inc. 3.8%
O'Reilly Automotive, Inc. 3.8%
* Excluding short-term investments
Top Industries 
Commercial Services & Supplies 12.1%
Insurance 11.5%
Software 9.5%
Machinery 7.6%
Chemicals 7.4%
Electronic Equipment, Instruments & Components 5.7%
Household Durables 5.4%
Financial Services 4.3%
Specialty Retail 3.8%
Specialized REITs 3.4%
Largest Holdings [Text Block]
Top Ten Holdings and/or Issuers*
Constellation Software, Inc. 9.2%
Progressive Corp. (The) 6.7%
NVR, Inc. 5.4%
Copart, Inc. 4.9%
Markel Group, Inc. 4.8%
Berkshire Hathaway, Inc., Class B 4.3%
Linde plc 4.1%
Cintas Corp. 4.0%
PACCAR, Inc. 3.8%
O'Reilly Automotive, Inc. 3.8%
* Excluding short-term investments
C000018721 [Member]  
Shareholder Report [Line Items]  
Fund Name NYLI WMC Enduring Capital Fund
Class Name Class C
Trading Symbol MGOCX
Annual or Semi-Annual Statement [Text Block] This semiannual shareholder report contains important information about NYLI WMC Enduring Capital Fund (the "Fund") for the period November 1, 2024 to April 30, 2025.
Shareholder Report Annual or Semi-Annual semi-annual shareholder report
Additional Information [Text Block] You can find additional information about the Fund at dfinview.com/NYLIM. You can also request this information by contacting us at 800-624-6782.
Additional Information Phone Number 800-624-6782
Additional Information Website dfinview.com/NYLIM
Expenses [Text Block]
What were the Fund costs for the last six months?
(Based on a hypothetical $10,000 investment)
Share Class Name Costs of a $10,000 investment Costs paid as a percentage
of a $10,000 investment1
Class C $95 1.90%
1.
Annualized.
Expenses Paid, Amount $ 95
Expense Ratio, Percent 1.90% [60]
Performance Past Does Not Indicate Future [Text] Keep in mind that the Fund ’s past performance is not a good predictor of how the Fund will perform in the future.
Line Graph [Table Text Block]
Fund Performance
The following graph compares the initial and subsequent account values at the end of each of the most recently completed 10 semiannual reporting periods of the Fund (or for the life of the Fund, if shorter). It assumes a $10,000 initial investment at the beginning of the first fiscal period in an appropriate, broad-based securities market index and other additional indexes, if applicable, for the same period and reflects the deduction of all sales charges, where applicable.
Fund Performance - Growth of 10K
Average Annual Return [Table Text Block]
Average Annual Total Returns for the Period Ended April 30, 2025 Inception
Date		 Six
Months1		 One
Year		 Five
Years		 Ten
Years
Class C Shares - Including sales charges 9/1/1998 0.73% 9.17% 14.12% 9.77%
Class C Shares - Excluding sales charges 1.73% 10.17% 14.12% 9.77%
Russell 3000®Index2 (2.15)% 11.40% 15.12% 11.68%
S&P 500®Index3 (1.74)% 12.10% 15.61% 12.32%
Morningstar Large Blend Category Average4 (2.35)% 9.59% 14.37% 10.85%
1.
Not annualized.
2.
The Fund has selected the Russell 3000® Index to represent a broad measure of market performance. The Russell 3000® Index measures the performance of the largest 3,000 U.S. companies representing approximately 98% of the investable U.S. equity market.
3.
The S&P 500® Index, which represents a broad measure of market performance, is generally representative of the market sectors or types of investments in which the Fund invests. S&P® and S&P 500® are registered trademarks of Standard & Poor’s Financial Services LLC. The S&P 500® Index is widely regarded as the standard index for measuring large-cap U.S. stock market performance.
4.
The Morningstar Large Blend Category Average is representative of funds that represent the overall U.S. stock market in size, growth rates and price. Stocks in the top 70% of the capitalization of the U.S. equity market are defined as large cap. The blend style is assigned to funds where neither growth nor value characteristics predominate. These funds tend to invest across the spectrum of U.S. industries, and owing to their broad exposure, the funds' returns are often similar to those of the S&P 500® Index. Results are based on average total returns of similar funds with all dividends and capital gain distributions reinvested.
Performance Inception Date Sep. 01, 1998
No Deduction of Taxes [Text Block] The graph and table do not reflect the deduction of taxes that a shareholder would pay on Fund distributions or redemption of Fund shares.
Updated Performance Information Location [Text Block] Visit newyorklifeinvestments.com/funds for the most recent performance information.
Net Assets $ 516,187,803
Holdings Count | Holding 34
Investment Company Portfolio Turnover 7.00%
Additional Fund Statistics [Text Block]
Key Fund Statistics
Fund's net assets $516,187,803%
Total number of portfolio holdings 34%
Portfolio turnover rate 7%
Holdings [Text Block]
Graphical Representation of Holdings
The tables below show the investment makeup of the Fund; percentages indicated are based on the Fund's net assets.
Top Ten Holdings and/or Issuers*
Constellation Software, Inc. 9.2%
Progressive Corp. (The) 6.7%
NVR, Inc. 5.4%
Copart, Inc. 4.9%
Markel Group, Inc. 4.8%
Berkshire Hathaway, Inc., Class B 4.3%
Linde plc 4.1%
Cintas Corp. 4.0%
PACCAR, Inc. 3.8%
O'Reilly Automotive, Inc. 3.8%
* Excluding short-term investments
Top Industries 
Commercial Services & Supplies 12.1%
Insurance 11.5%
Software 9.5%
Machinery 7.6%
Chemicals 7.4%
Electronic Equipment, Instruments & Components 5.7%
Household Durables 5.4%
Financial Services 4.3%
Specialty Retail 3.8%
Specialized REITs 3.4%
Largest Holdings [Text Block]
Top Ten Holdings and/or Issuers*
Constellation Software, Inc. 9.2%
Progressive Corp. (The) 6.7%
NVR, Inc. 5.4%
Copart, Inc. 4.9%
Markel Group, Inc. 4.8%
Berkshire Hathaway, Inc., Class B 4.3%
Linde plc 4.1%
Cintas Corp. 4.0%
PACCAR, Inc. 3.8%
O'Reilly Automotive, Inc. 3.8%
* Excluding short-term investments
C000018722 [Member]  
Shareholder Report [Line Items]  
Fund Name NYLI WMC Enduring Capital Fund
Class Name Class I
Trading Symbol MSOIX
Annual or Semi-Annual Statement [Text Block] This semiannual shareholder report contains important information about NYLI WMC Enduring Capital Fund (the "Fund") for the period November 1, 2024 to April 30, 2025.
Shareholder Report Annual or Semi-Annual semi-annual shareholder report
Additional Information [Text Block] You can find additional information about the Fund at dfinview.com/NYLIM. You can also request this information by contacting us at 800-624-6782.
Additional Information Phone Number 800-624-6782
Additional Information Website dfinview.com/NYLIM
Expenses [Text Block]
What were the Fund costs for the last six months?
(Based on a hypothetical $10,000 investment)
Share Class Name Costs of a $10,000 investment Costs paid as a percentage
of a $10,000 investment1
Class I $33 0.67%
1.
Annualized.
Expenses Paid, Amount $ 33
Expense Ratio, Percent 0.67% [61]
Performance Past Does Not Indicate Future [Text] Keep in mind that the Fund ’s past performance is not a good predictor of how the Fund will perform in the future.
Line Graph [Table Text Block]
Fund Performance
The following graph compares the initial and subsequent account values at the end of each of the most recently completed 10 semiannual reporting periods of the Fund (or for the life of the Fund, if shorter). It assumes a $10,000 initial investment at the beginning of the first fiscal period in an appropriate, broad-based securities market index and other additional indexes, if applicable, for the same period and reflects the deduction of all sales charges, where applicable.
Fund Performance - Growth of 10K
Average Annual Return [Table Text Block]
Average Annual Total Returns for the Period Ended April 30, 2025 Inception
Date		 Six
Months1		 One
Year		 Five
Years		 Ten
Years
Class I Shares 12/28/2004 2.36% 11.54% 15.54% 11.15%
Russell 3000®Index2 (2.15)% 11.40% 15.12% 11.68%
S&P 500®Index3 (1.74)% 12.10% 15.61% 12.32%
Morningstar Large Blend Category Average4 (2.35)% 9.59% 14.37% 10.85%
1.
Not annualized.
2.
The Fund has selected the Russell 3000® Index to represent a broad measure of market performance. The Russell 3000® Index measures the performance of the largest 3,000 U.S. companies representing approximately 98% of the investable U.S. equity market.
3.
The S&P 500® Index, which represents a broad measure of market performance, is generally representative of the market sectors or types of investments in which the Fund invests. S&P® and S&P 500® are registered trademarks of Standard & Poor’s Financial Services LLC. The S&P 500® Index is widely regarded as the standard index for measuring large-cap U.S. stock market performance.
4.
The Morningstar Large Blend Category Average is representative of funds that represent the overall U.S. stock market in size, growth rates and price. Stocks in the top 70% of the capitalization of the U.S. equity market are defined as large cap. The blend style is assigned to funds where neither growth nor value characteristics predominate. These funds tend to invest across the spectrum of U.S. industries, and owing to their broad exposure, the funds' returns are often similar to those of the S&P 500® Index. Results are based on average total returns of similar funds with all dividends and capital gain distributions reinvested.
Performance Inception Date Dec. 28, 2004
No Deduction of Taxes [Text Block] The graph and table do not reflect the deduction of taxes that a shareholder would pay on Fund distributions or redemption of Fund shares.
Updated Performance Information Location [Text Block] Visit newyorklifeinvestments.com/funds for the most recent performance information.
Net Assets $ 516,187,803
Holdings Count | Holding 34
Investment Company Portfolio Turnover 7.00%
Additional Fund Statistics [Text Block]
Key Fund Statistics
Fund's net assets $516,187,803%
Total number of portfolio holdings 34%
Portfolio turnover rate 7%
Holdings [Text Block]
Graphical Representation of Holdings
The tables below show the investment makeup of the Fund; percentages indicated are based on the Fund's net assets.
Top Ten Holdings and/or Issuers*
Constellation Software, Inc. 9.2%
Progressive Corp. (The) 6.7%
NVR, Inc. 5.4%
Copart, Inc. 4.9%
Markel Group, Inc. 4.8%
Berkshire Hathaway, Inc., Class B 4.3%
Linde plc 4.1%
Cintas Corp. 4.0%
PACCAR, Inc. 3.8%
O'Reilly Automotive, Inc. 3.8%
* Excluding short-term investments
Top Industries 
Commercial Services & Supplies 12.1%
Insurance 11.5%
Software 9.5%
Machinery 7.6%
Chemicals 7.4%
Electronic Equipment, Instruments & Components 5.7%
Household Durables 5.4%
Financial Services 4.3%
Specialty Retail 3.8%
Specialized REITs 3.4%
Largest Holdings [Text Block]
Top Ten Holdings and/or Issuers*
Constellation Software, Inc. 9.2%
Progressive Corp. (The) 6.7%
NVR, Inc. 5.4%
Copart, Inc. 4.9%
Markel Group, Inc. 4.8%
Berkshire Hathaway, Inc., Class B 4.3%
Linde plc 4.1%
Cintas Corp. 4.0%
PACCAR, Inc. 3.8%
O'Reilly Automotive, Inc. 3.8%
* Excluding short-term investments
C000179143 [Member]  
Shareholder Report [Line Items]  
Fund Name NYLI WMC Enduring Capital Fund
Class Name Class R6
Trading Symbol MCSDX
Annual or Semi-Annual Statement [Text Block] This semiannual shareholder report contains important information about NYLI WMC Enduring Capital Fund (the "Fund") for the period November 1, 2024 to April 30, 2025.
Shareholder Report Annual or Semi-Annual semi-annual shareholder report
Additional Information [Text Block] You can find additional information about the Fund at dfinview.com/NYLIM. You can also request this information by contacting us at 800-624-6782.
Additional Information Phone Number 800-624-6782
Additional Information Website dfinview.com/NYLIM
Expenses [Text Block]
What were the Fund costs for the last six months?
(Based on a hypothetical $10,000 investment)
Share Class Name Costs of a $10,000 investment Costs paid as a percentage
of a $10,000 investment1
Class R6 $30 0.60%
1.
Annualized.
Expenses Paid, Amount $ 30
Expense Ratio, Percent 0.60% [62]
Performance Past Does Not Indicate Future [Text] Keep in mind that the Fund ’s past performance is not a good predictor of how the Fund will perform in the future.
Line Graph [Table Text Block]
Fund Performance
The following graph compares the initial and subsequent account values at the end of each of the most recently completed 10 semiannual reporting periods of the Fund (or for the life of the Fund, if shorter). It assumes a $10,000 initial investment at the beginning of the first fiscal period in an appropriate, broad-based securities market index and other additional indexes, if applicable, for the same period and reflects the deduction of all sales charges, where applicable.
Fund Performance - Growth of 10K
Average Annual Return [Table Text Block]
Average Annual Total Returns for the Period Ended April 30, 2025 Inception
Date		 Six
Months1		 One
Year		 Since
Inception
Class R6 Shares 4/26/2021 2.37% 11.58% 8.59%
Russell 3000®Index2 (2.15)% 11.40% 7.46%
S&P 500®Index3 (1.74)% 12.10% 8.99%
Morningstar Large Blend Category Average4 (2.35)% 9.59% 6.90%
1.
Not annualized.
2.
The Fund has selected the Russell 3000® Index to represent a broad measure of market performance. The Russell 3000® Index measures the performance of the largest 3,000 U.S. companies representing approximately 98% of the investable U.S. equity market.
3.
The S&P 500® Index, which represents a broad measure of market performance, is generally representative of the market sectors or types of investments in which the Fund invests. S&P® and S&P 500® are registered trademarks of Standard & Poor’s Financial Services LLC. The S&P 500® Index is widely regarded as the standard index for measuring large-cap U.S. stock market performance.
4.
The Morningstar Large Blend Category Average is representative of funds that represent the overall U.S. stock market in size, growth rates and price. Stocks in the top 70% of the capitalization of the U.S. equity market are defined as large cap. The blend style is assigned to funds where neither growth nor value characteristics predominate. These funds tend to invest across the spectrum of U.S. industries, and owing to their broad exposure, the funds' returns are often similar to those of the S&P 500® Index. Results are based on average total returns of similar funds with all dividends and capital gain distributions reinvested.
Performance Inception Date Apr. 26, 2021
No Deduction of Taxes [Text Block] The graph and table do not reflect the deduction of taxes that a shareholder would pay on Fund distributions or redemption of Fund shares.
Updated Performance Information Location [Text Block] Visit newyorklifeinvestments.com/funds for the most recent performance information.
Net Assets $ 516,187,803
Holdings Count | Holding 34
Investment Company Portfolio Turnover 7.00%
Additional Fund Statistics [Text Block]
Key Fund Statistics
Fund's net assets $516,187,803%
Total number of portfolio holdings 34%
Portfolio turnover rate 7%
Holdings [Text Block]
Graphical Representation of Holdings
The tables below show the investment makeup of the Fund; percentages indicated are based on the Fund's net assets.
Top Ten Holdings and/or Issuers*
Constellation Software, Inc. 9.2%
Progressive Corp. (The) 6.7%
NVR, Inc. 5.4%
Copart, Inc. 4.9%
Markel Group, Inc. 4.8%
Berkshire Hathaway, Inc., Class B 4.3%
Linde plc 4.1%
Cintas Corp. 4.0%
PACCAR, Inc. 3.8%
O'Reilly Automotive, Inc. 3.8%
* Excluding short-term investments
Top Industries 
Commercial Services & Supplies 12.1%
Insurance 11.5%
Software 9.5%
Machinery 7.6%
Chemicals 7.4%
Electronic Equipment, Instruments & Components 5.7%
Household Durables 5.4%
Financial Services 4.3%
Specialty Retail 3.8%
Specialized REITs 3.4%
Largest Holdings [Text Block]
Top Ten Holdings and/or Issuers*
Constellation Software, Inc. 9.2%
Progressive Corp. (The) 6.7%
NVR, Inc. 5.4%
Copart, Inc. 4.9%
Markel Group, Inc. 4.8%
Berkshire Hathaway, Inc., Class B 4.3%
Linde plc 4.1%
Cintas Corp. 4.0%
PACCAR, Inc. 3.8%
O'Reilly Automotive, Inc. 3.8%
* Excluding short-term investments
C000060799 [Member]  
Shareholder Report [Line Items]  
Fund Name NYLI WMC Enduring Capital Fund
Class Name Investor Class
Trading Symbol MCSSX
Annual or Semi-Annual Statement [Text Block] This semiannual shareholder report contains important information about NYLI WMC Enduring Capital Fund (the "Fund") for the period November 1, 2024 to April 30, 2025.
Shareholder Report Annual or Semi-Annual semi-annual shareholder report
Additional Information [Text Block] You can find additional information about the Fund at dfinview.com/NYLIM. You can also request this information by contacting us at 800-624-6782.
Additional Information Phone Number 800-624-6782
Additional Information Website dfinview.com/NYLIM
Expenses [Text Block]
What were the Fund costs for the last six months?
(Based on a hypothetical $10,000 investment)
Share Class Name Costs of a $10,000 investment Costs paid as a percentage
of a $10,000 investment1
Investor Class $58 1.15%
1.
Annualized.
Expenses Paid, Amount $ 58
Expense Ratio, Percent 1.15% [63]
Performance Past Does Not Indicate Future [Text] Keep in mind that the Fund ’s past performance is not a good predictor of how the Fund will perform in the future.
Line Graph [Table Text Block]
Fund Performance
The following graph compares the initial and subsequent account values at the end of each of the most recently completed 10 semiannual reporting periods of the Fund (or for the life of the Fund, if shorter). It assumes a $10,000 initial investment at the beginning of the first fiscal period in an appropriate, broad-based securities market index and other additional indexes, if applicable, for the same period and reflects the deduction of all sales charges, where applicable.
Fund Performance - Growth of 10K
Average Annual Return [Table Text Block]
Average Annual Total Returns for the Period Ended April 30, 2025 Inception
Date		 Six
Months1		 One
Year		 Five
Years		 Ten
Years
Investor Class Shares - Including sales charges 2/28/2008 (3.01)% 5.43% 13.69% 9.98%
Investor Class Shares - Excluding sales charges 2.10% 10.98% 14.99% 10.60%
Russell 3000®Index2 (2.15)% 11.40% 15.12% 11.68%
S&P 500®Index3 (1.74)% 12.10% 15.61% 12.32%
Morningstar Large Blend Category Average4 (2.35)% 9.59% 14.37% 10.85%
1.
Not annualized.
2.
The Fund has selected the Russell 3000® Index to represent a broad measure of market performance. The Russell 3000® Index measures the performance of the largest 3,000 U.S. companies representing approximately 98% of the investable U.S. equity market.
3.
The S&P 500® Index, which represents a broad measure of market performance, is generally representative of the market sectors or types of investments in which the Fund invests. S&P® and S&P 500® are registered trademarks of Standard & Poor’s Financial Services LLC. The S&P 500® Index is widely regarded as the standard index for measuring large-cap U.S. stock market performance.
4.
The Morningstar Large Blend Category Average is representative of funds that represent the overall U.S. stock market in size, growth rates and price. Stocks in the top 70% of the capitalization of the U.S. equity market are defined as large cap. The blend style is assigned to funds where neither growth nor value characteristics predominate. These funds tend to invest across the spectrum of U.S. industries, and owing to their broad exposure, the funds' returns are often similar to those of the S&P 500® Index. Results are based on average total returns of similar funds with all dividends and capital gain distributions reinvested.
Performance Inception Date Feb. 28, 2008
No Deduction of Taxes [Text Block] The graph and table do not reflect the deduction of taxes that a shareholder would pay on Fund distributions or redemption of Fund shares.
Updated Performance Information Location [Text Block] Visit newyorklifeinvestments.com/funds for the most recent performance information.
Net Assets $ 516,187,803
Holdings Count | Holding 34
Investment Company Portfolio Turnover 7.00%
Additional Fund Statistics [Text Block]
Key Fund Statistics
Fund's net assets $516,187,803%
Total number of portfolio holdings 34%
Portfolio turnover rate 7%
Holdings [Text Block]
Graphical Representation of Holdings
The tables below show the investment makeup of the Fund; percentages indicated are based on the Fund's net assets.
Top Ten Holdings and/or Issuers*
Constellation Software, Inc. 9.2%
Progressive Corp. (The) 6.7%
NVR, Inc. 5.4%
Copart, Inc. 4.9%
Markel Group, Inc. 4.8%
Berkshire Hathaway, Inc., Class B 4.3%
Linde plc 4.1%
Cintas Corp. 4.0%
PACCAR, Inc. 3.8%
O'Reilly Automotive, Inc. 3.8%
* Excluding short-term investments
Top Industries 
Commercial Services & Supplies 12.1%
Insurance 11.5%
Software 9.5%
Machinery 7.6%
Chemicals 7.4%
Electronic Equipment, Instruments & Components 5.7%
Household Durables 5.4%
Financial Services 4.3%
Specialty Retail 3.8%
Specialized REITs 3.4%
Largest Holdings [Text Block]
Top Ten Holdings and/or Issuers*
Constellation Software, Inc. 9.2%
Progressive Corp. (The) 6.7%
NVR, Inc. 5.4%
Copart, Inc. 4.9%
Markel Group, Inc. 4.8%
Berkshire Hathaway, Inc., Class B 4.3%
Linde plc 4.1%
Cintas Corp. 4.0%
PACCAR, Inc. 3.8%
O'Reilly Automotive, Inc. 3.8%
* Excluding short-term investments
C000018724 [Member]  
Shareholder Report [Line Items]  
Fund Name NYLI Winslow Large Cap Growth Fund
Class Name Class A
Trading Symbol MLAAX
Annual or Semi-Annual Statement [Text Block] This semiannual shareholder report contains important information about NYLI Winslow Large Cap Growth Fund (the "Fund") for the period November 1, 2024 to April 30, 2025.
Shareholder Report Annual or Semi-Annual semi-annual shareholder report
Additional Information [Text Block] You can find additional information about the Fund at dfinview.com/NYLIM. You can also request this information by contacting us at 800-624-6782.
Additional Information Phone Number 800-624-6782
Additional Information Website dfinview.com/NYLIM
Expenses [Text Block]
What were the Fund costs for the last six months?
(Based on a hypothetical $10,000 investment)
Share Class Name Costs of a $10,000 investment Costs paid as a percentage
of a $10,000 investment1,2
Class A $47 0.94%
1.
Reflects fee waivers and/or expense reimbursements, without which expenses would have been higher.
2.
Annualized.
Expenses Paid, Amount $ 47
Expense Ratio, Percent 0.94% [64],[65]
Performance Past Does Not Indicate Future [Text] Keep in mind that the Fund ’s past performance is not a good predictor of how the Fund will perform in the future.
Line Graph [Table Text Block]
Fund Performance
The following graph compares the initial and subsequent account values at the end of each of the most recently completed 10 semiannual reporting periods of the Fund (or for the life of the Fund, if shorter). It assumes a $15,000 initial investment at the beginning of the first fiscal period in an appropriate, broad-based securities market index and other additional indexes, if applicable, for the same period and reflects the deduction of all sales charges, where applicable.
Fund Performance - Growth of 10K
Average Annual Return [Table Text Block]
Average Annual Total Returns for the Period Ended April 30, 2025 Inception
Date		 Six
Months1		 One
Year		 Five
Years		 Ten
Years
Class A Shares - Including sales charges 7/1/1995 (6.28)% 6.95% 13.98% 13.36%
Class A Shares - Excluding sales charges (0.82)% 13.17% 15.27% 14.01%
Russell 3000®Index2 (2.15)% 11.40% 15.12% 11.68%
Russell 1000® Growth Index3 (1.57)% 14.53% 17.23% 15.27%
S&P 500®Index4 (1.74)% 12.10% 15.61% 12.32%
Morningstar Large Growth Category Average5 (1.64)% 12.32% 14.18% 12.78%
1.
Not annualized.
2.
The Fund has selected the Russell 3000® Index to represent a broad measure of market performance. The Russell 3000® Index measures the performance of the largest 3,000 U.S. companies representing approximately 98% of the investable U.S. equity market.
3.
The Russell 1000® Growth Index, which is generally representative of the market sectors or types of investments in which the Fund invests, measures the performance of the large-cap growth segment of the U.S. equity universe. It includes those Russell 1000® Index companies with higher price-to-book ratios and higher forecasted growth values.
4.
The S&P 500® Index, which represents a broad measure of market performance, is generally representative of the market sectors or types of investments in which the Fund invests. S&P® and S&P 500® are registered trademarks of Standard & Poor’s Financial Services LLC. The S&P 500® Index is widely regarded as the standard index for measuring large-cap U.S. stock market performance.
5.
The Morningstar Large Growth Category Average is representative of funds that invest primarily in big U.S. companies that are projected to grow faster than other large-cap stocks. Stocks in the top 70% of the capitalization of the U.S. equity market are defined as large cap. Growth is defined based on fast growth and high valuations. Most of these funds focus on companies in rapidly expanding industries. Results are based on average total returns of similar funds with all dividends and capital gain distributions reinvested.
Performance Inception Date Jul. 01, 1995
No Deduction of Taxes [Text Block] The graph and table do not reflect the deduction of taxes that a shareholder would pay on Fund distributions or redemption of Fund shares.
Updated Performance Information Location [Text Block] Visit newyorklifeinvestments.com/funds for the most recent performance information.
Net Assets $ 12,360,651,183
Holdings Count | Holding 44
Investment Company Portfolio Turnover 42.00%
Additional Fund Statistics [Text Block]
Key Fund Statistics
Fund's net assets $12,360,651,183%
Total number of portfolio holdings 44%
Portfolio turnover rate 42%
Holdings [Text Block]
Graphical Representation of Holdings
The tables below show the investment makeup of the Fund; percentages indicated are based on the Fund's net assets.
Top Ten Holdings and/or Issuers*
Microsoft Corp. 9.4%
Amazon.com, Inc. 6.8%
NVIDIA Corp. 6.4%
Apple, Inc. 5.6%
Meta Platforms, Inc., Class A 5.0%
Broadcom, Inc. 4.2%
Eli Lilly & Co. 4.1%
Visa, Inc., Class A 3.2%
Netflix, Inc. 3.0%
Spotify Technology SA 2.9%
* Excluding short-term investments
Top Industries 
Software 17.3%
Semiconductors & Semiconductor Equipment 13.9%
Interactive Media & Services 7.6%
Financial Services 7.2%
Broadline Retail 6.8%
Hotels, Restaurants & Leisure 6.3%
Entertainment 5.9%
Technology Hardware, Storage & Peripherals 5.6%
Health Care Equipment & Supplies 5.4%
Aerospace & Defense 4.6%
Largest Holdings [Text Block]
Top Ten Holdings and/or Issuers*
Microsoft Corp. 9.4%
Amazon.com, Inc. 6.8%
NVIDIA Corp. 6.4%
Apple, Inc. 5.6%
Meta Platforms, Inc., Class A 5.0%
Broadcom, Inc. 4.2%
Eli Lilly & Co. 4.1%
Visa, Inc., Class A 3.2%
Netflix, Inc. 3.0%
Spotify Technology SA 2.9%
* Excluding short-term investments
C000018726 [Member]  
Shareholder Report [Line Items]  
Fund Name NYLI Winslow Large Cap Growth Fund
Class Name Class C
Trading Symbol MLACX
Annual or Semi-Annual Statement [Text Block] This semiannual shareholder report contains important information about NYLI Winslow Large Cap Growth Fund (the "Fund") for the period November 1, 2024 to April 30, 2025.
Shareholder Report Annual or Semi-Annual semi-annual shareholder report
Additional Information [Text Block] You can find additional information about the Fund at dfinview.com/NYLIM. You can also request this information by contacting us at 800-624-6782.
Additional Information Phone Number 800-624-6782
Additional Information Website dfinview.com/NYLIM
Expenses [Text Block]
What were the Fund costs for the last six months?
(Based on a hypothetical $10,000 investment)
Share Class Name Costs of a $10,000 investment Costs paid as a percentage
of a $10,000 investment1,2
Class C $92 1.87%
1.
Reflects fee waivers and/or expense reimbursements, without which expenses would have been higher.
2.
Annualized.
Expenses Paid, Amount $ 92
Expense Ratio, Percent 1.87% [66],[67]
Performance Past Does Not Indicate Future [Text] Keep in mind that the Fund ’s past performance is not a good predictor of how the Fund will perform in the future.
Line Graph [Table Text Block]
Fund Performance
The following graph compares the initial and subsequent account values at the end of each of the most recently completed 10 semiannual reporting periods of the Fund (or for the life of the Fund, if shorter). It assumes a $10,000 initial investment at the beginning of the first fiscal period in an appropriate, broad-based securities market index and other additional indexes, if applicable, for the same period and reflects the deduction of all sales charges, where applicable.
Fund Performance - Growth of 10K
Average Annual Return [Table Text Block]
Average Annual Total Returns for the Period Ended April 30, 2025 Inception
Date		 Six
Months1		 One
Year		 Five
Years		 Ten
Years
Class C Shares - Including sales charges 4/1/2005 (1.92)% 11.56% 14.22% 13.03%
Class C Shares - Excluding sales charges (1.26)% 12.32% 14.22% 13.03%
Russell 3000®Index2 (2.15)% 11.40% 15.12% 11.68%
Russell 1000® Growth Index3 (1.57)% 14.53% 17.23% 15.27%
S&P 500®Index4 (1.74)% 12.10% 15.61% 12.32%
Morningstar Large Growth Category Average5 (1.64)% 12.32% 14.18% 12.78%
1.
Not annualized.
2.
The Fund has selected the Russell 3000® Index to represent a broad measure of market performance. The Russell 3000® Index measures the performance of the largest 3,000 U.S. companies representing approximately 98% of the investable U.S. equity market.
3.
The Russell 1000® Growth Index, which is generally representative of the market sectors or types of investments in which the Fund invests, measures the performance of the large-cap growth segment of the U.S. equity universe. It includes those Russell 1000® Index companies with higher price-to-book ratios and higher forecasted growth values.
4.
The S&P 500® Index, which represents a broad measure of market performance, is generally representative of the market sectors or types of investments in which the Fund invests. S&P® and S&P 500® are registered trademarks of Standard & Poor’s Financial Services LLC. The S&P 500® Index is widely regarded as the standard index for measuring large-cap U.S. stock market performance.
5.
The Morningstar Large Growth Category Average is representative of funds that invest primarily in big U.S. companies that are projected to grow faster than other large-cap stocks. Stocks in the top 70% of the capitalization of the U.S. equity market are defined as large cap. Growth is defined based on fast growth and high valuations. Most of these funds focus on companies in rapidly expanding industries. Results are based on average total returns of similar funds with all dividends and capital gain distributions reinvested.
Performance Inception Date Apr. 01, 2005
No Deduction of Taxes [Text Block] The graph and table do not reflect the deduction of taxes that a shareholder would pay on Fund distributions or redemption of Fund shares.
Updated Performance Information Location [Text Block] Visit newyorklifeinvestments.com/funds for the most recent performance information.
Net Assets $ 12,360,651,183
Holdings Count | Holding 44
Investment Company Portfolio Turnover 42.00%
Additional Fund Statistics [Text Block]
Key Fund Statistics
Fund's net assets $12,360,651,183%
Total number of portfolio holdings 44%
Portfolio turnover rate 42%
Holdings [Text Block]
Graphical Representation of Holdings
The tables below show the investment makeup of the Fund; percentages indicated are based on the Fund's net assets.
Top Ten Holdings and/or Issuers*
Microsoft Corp. 9.4%
Amazon.com, Inc. 6.8%
NVIDIA Corp. 6.4%
Apple, Inc. 5.6%
Meta Platforms, Inc., Class A 5.0%
Broadcom, Inc. 4.2%
Eli Lilly & Co. 4.1%
Visa, Inc., Class A 3.2%
Netflix, Inc. 3.0%
Spotify Technology SA 2.9%
* Excluding short-term investments
Top Industries 
Software 17.3%
Semiconductors & Semiconductor Equipment 13.9%
Interactive Media & Services 7.6%
Financial Services 7.2%
Broadline Retail 6.8%
Hotels, Restaurants & Leisure 6.3%
Entertainment 5.9%
Technology Hardware, Storage & Peripherals 5.6%
Health Care Equipment & Supplies 5.4%
Aerospace & Defense 4.6%
Largest Holdings [Text Block]
Top Ten Holdings and/or Issuers*
Microsoft Corp. 9.4%
Amazon.com, Inc. 6.8%
NVIDIA Corp. 6.4%
Apple, Inc. 5.6%
Meta Platforms, Inc., Class A 5.0%
Broadcom, Inc. 4.2%
Eli Lilly & Co. 4.1%
Visa, Inc., Class A 3.2%
Netflix, Inc. 3.0%
Spotify Technology SA 2.9%
* Excluding short-term investments
C000018727 [Member]  
Shareholder Report [Line Items]  
Fund Name NYLI Winslow Large Cap Growth Fund
Class Name Class I
Trading Symbol MLAIX
Annual or Semi-Annual Statement [Text Block] This semiannual shareholder report contains important information about NYLI Winslow Large Cap Growth Fund (the "Fund") for the period November 1, 2024 to April 30, 2025.
Shareholder Report Annual or Semi-Annual semi-annual shareholder report
Additional Information [Text Block] You can find additional information about the Fund at dfinview.com/NYLIM. You can also request this information by contacting us at 800-624-6782.
Additional Information Phone Number 800-624-6782
Additional Information Website dfinview.com/NYLIM
Expenses [Text Block]
What were the Fund costs for the last six months?
(Based on a hypothetical $10,000 investment)
Share Class Name Costs of a $10,000 investment Costs paid as a percentage
of a $10,000 investment1,2
Class I $34 0.69%
1.
Reflects fee waivers and/or expense reimbursements, without which expenses would have been higher.
2.
Annualized.
Expenses Paid, Amount $ 34
Expense Ratio, Percent 0.69% [68],[69]
Performance Past Does Not Indicate Future [Text] Keep in mind that the Fund ’s past performance is not a good predictor of how the Fund will perform in the future.
Line Graph [Table Text Block]
Fund Performance
The following graph compares the initial and subsequent account values at the end of each of the most recently completed 10 semiannual reporting periods of the Fund (or for the life of the Fund, if shorter). It assumes a $10,000 initial investment at the beginning of the first fiscal period in an appropriate, broad-based securities market index and other additional indexes, if applicable, for the same period and reflects the deduction of all sales charges, where applicable.
Fund Performance - Growth of 10K
Average Annual Return [Table Text Block]
Average Annual Total Returns for the Period Ended April 30, 2025 Inception
Date		 Six
Months1		 One
Year		 Five
Years		 Ten
Years
Class I Shares 4/1/2005 (0.76)% 13.37% 15.53% 14.28%
Russell 3000®Index2 (2.15)% 11.40% 15.12% 11.68%
Russell 1000® Growth Index3 (1.57)% 14.53% 17.23% 15.27%
S&P 500®Index4 (1.74)% 12.10% 15.61% 12.32%
Morningstar Large Growth Category Average5 (1.64)% 12.32% 14.18% 12.78%
1.
Not annualized.
2.
The Fund has selected the Russell 3000® Index to represent a broad measure of market performance. The Russell 3000® Index measures the performance of the largest 3,000 U.S. companies representing approximately 98% of the investable U.S. equity market.
3.
The Russell 1000® Growth Index, which is generally representative of the market sectors or types of investments in which the Fund invests, measures the performance of the large-cap growth segment of the U.S. equity universe. It includes those Russell 1000® Index companies with higher price-to-book ratios and higher forecasted growth values.
4.
The S&P 500® Index, which represents a broad measure of market performance, is generally representative of the market sectors or types of investments in which the Fund invests. S&P® and S&P 500® are registered trademarks of Standard & Poor’s Financial Services LLC. The S&P 500® Index is widely regarded as the standard index for measuring large-cap U.S. stock market performance.
5.
The Morningstar Large Growth Category Average is representative of funds that invest primarily in big U.S. companies that are projected to grow faster than other large-cap stocks. Stocks in the top 70% of the capitalization of the U.S. equity market are defined as large cap. Growth is defined based on fast growth and high valuations. Most of these funds focus on companies in rapidly expanding industries. Results are based on average total returns of similar funds with all dividends and capital gain distributions reinvested.
Performance Inception Date Apr. 01, 2005
No Deduction of Taxes [Text Block] The graph and table do not reflect the deduction of taxes that a shareholder would pay on Fund distributions or redemption of Fund shares.
Updated Performance Information Location [Text Block] Visit newyorklifeinvestments.com/funds for the most recent performance information.
Net Assets $ 12,360,651,183
Holdings Count | Holding 44
Investment Company Portfolio Turnover 42.00%
Additional Fund Statistics [Text Block]
Key Fund Statistics
Fund's net assets $12,360,651,183%
Total number of portfolio holdings 44%
Portfolio turnover rate 42%
Holdings [Text Block]
Graphical Representation of Holdings
The tables below show the investment makeup of the Fund; percentages indicated are based on the Fund's net assets.
Top Ten Holdings and/or Issuers*
Microsoft Corp. 9.4%
Amazon.com, Inc. 6.8%
NVIDIA Corp. 6.4%
Apple, Inc. 5.6%
Meta Platforms, Inc., Class A 5.0%
Broadcom, Inc. 4.2%
Eli Lilly & Co. 4.1%
Visa, Inc., Class A 3.2%
Netflix, Inc. 3.0%
Spotify Technology SA 2.9%
* Excluding short-term investments
Top Industries 
Software 17.3%
Semiconductors & Semiconductor Equipment 13.9%
Interactive Media & Services 7.6%
Financial Services 7.2%
Broadline Retail 6.8%
Hotels, Restaurants & Leisure 6.3%
Entertainment 5.9%
Technology Hardware, Storage & Peripherals 5.6%
Health Care Equipment & Supplies 5.4%
Aerospace & Defense 4.6%
Largest Holdings [Text Block]
Top Ten Holdings and/or Issuers*
Microsoft Corp. 9.4%
Amazon.com, Inc. 6.8%
NVIDIA Corp. 6.4%
Apple, Inc. 5.6%
Meta Platforms, Inc., Class A 5.0%
Broadcom, Inc. 4.2%
Eli Lilly & Co. 4.1%
Visa, Inc., Class A 3.2%
Netflix, Inc. 3.0%
Spotify Technology SA 2.9%
* Excluding short-term investments
C000018728 [Member]  
Shareholder Report [Line Items]  
Fund Name NYLI Winslow Large Cap Growth Fund
Class Name Class R1
Trading Symbol MLRRX
Annual or Semi-Annual Statement [Text Block] This semiannual shareholder report contains important information about NYLI Winslow Large Cap Growth Fund (the "Fund") for the period November 1, 2024 to April 30, 2025.
Shareholder Report Annual or Semi-Annual semi-annual shareholder report
Additional Information [Text Block] You can find additional information about the Fund at dfinview.com/NYLIM. You can also request this information by contacting us at 800-624-6782.
Additional Information Phone Number 800-624-6782
Additional Information Website dfinview.com/NYLIM
Expenses [Text Block]
What were the Fund costs for the last six months?
(Based on a hypothetical $10,000 investment)
Share Class Name Costs of a $10,000 investment Costs paid as a percentage
of a $10,000 investment1,2
Class R1 $39 0.79%
1.
Reflects fee waivers and/or expense reimbursements, without which expenses would have been higher.
2.
Annualized.
Expenses Paid, Amount $ 39
Expense Ratio, Percent 0.79% [70],[71]
Performance Past Does Not Indicate Future [Text] Keep in mind that the Fund ’s past performance is not a good predictor of how the Fund will perform in the future.
Line Graph [Table Text Block]
Fund Performance
The following graph compares the initial and subsequent account values at the end of each of the most recently completed 10 semiannual reporting periods of the Fund (or for the life of the Fund, if shorter). It assumes a $10,000 initial investment at the beginning of the first fiscal period in an appropriate, broad-based securities market index and other additional indexes, if applicable, for the same period and reflects the deduction of all sales charges, where applicable.
Fund Performance - Growth of 10K
Average Annual Return [Table Text Block]
Average Annual Total Returns for the Period Ended April 30, 2025 Inception
Date		 Six
Months1		 One
Year		 Five
Years		 Ten
Years
Class R1 Shares 4/1/2005 (0.81)% 13.29% 15.41% 14.17%
Russell 3000®Index2 (2.15)% 11.40% 15.12% 11.68%
Russell 1000® Growth Index3 (1.57)% 14.53% 17.23% 15.27%
S&P 500®Index4 (1.74)% 12.10% 15.61% 12.32%
Morningstar Large Growth Category Average5 (1.64)% 12.32% 14.18% 12.78%
1.
Not annualized.
2.
The Fund has selected the Russell 3000® Index to represent a broad measure of market performance. The Russell 3000® Index measures the performance of the largest 3,000 U.S. companies representing approximately 98% of the investable U.S. equity market.
3.
The Russell 1000® Growth Index, which is generally representative of the market sectors or types of investments in which the Fund invests, measures the performance of the large-cap growth segment of the U.S. equity universe. It includes those Russell 1000® Index companies with higher price-to-book ratios and higher forecasted growth values.
4.
The S&P 500® Index, which represents a broad measure of market performance, is generally representative of the market sectors or types of investments in which the Fund invests. S&P® and S&P 500® are registered trademarks of Standard & Poor’s Financial Services LLC. The S&P 500® Index is widely regarded as the standard index for measuring large-cap U.S. stock market performance.
5.
The Morningstar Large Growth Category Average is representative of funds that invest primarily in big U.S. companies that are projected to grow faster than other large-cap stocks. Stocks in the top 70% of the capitalization of the U.S. equity market are defined as large cap. Growth is defined based on fast growth and high valuations. Most of these funds focus on companies in rapidly expanding industries. Results are based on average total returns of similar funds with all dividends and capital gain distributions reinvested.
Performance Inception Date Apr. 01, 2005
No Deduction of Taxes [Text Block] The graph and table do not reflect the deduction of taxes that a shareholder would pay on Fund distributions or redemption of Fund shares.
Updated Performance Information Location [Text Block] Visit newyorklifeinvestments.com/funds for the most recent performance information.
Net Assets $ 12,360,651,183
Holdings Count | Holding 44
Investment Company Portfolio Turnover 42.00%
Additional Fund Statistics [Text Block]
Key Fund Statistics
Fund's net assets $12,360,651,183%
Total number of portfolio holdings 44%
Portfolio turnover rate 42%
Holdings [Text Block]
Graphical Representation of Holdings
The tables below show the investment makeup of the Fund; percentages indicated are based on the Fund's net assets.
Top Ten Holdings and/or Issuers*
Microsoft Corp. 9.4%
Amazon.com, Inc. 6.8%
NVIDIA Corp. 6.4%
Apple, Inc. 5.6%
Meta Platforms, Inc., Class A 5.0%
Broadcom, Inc. 4.2%
Eli Lilly & Co. 4.1%
Visa, Inc., Class A 3.2%
Netflix, Inc. 3.0%
Spotify Technology SA 2.9%
* Excluding short-term investments
Top Industries 
Software 17.3%
Semiconductors & Semiconductor Equipment 13.9%
Interactive Media & Services 7.6%
Financial Services 7.2%
Broadline Retail 6.8%
Hotels, Restaurants & Leisure 6.3%
Entertainment 5.9%
Technology Hardware, Storage & Peripherals 5.6%
Health Care Equipment & Supplies 5.4%
Aerospace & Defense 4.6%
Largest Holdings [Text Block]
Top Ten Holdings and/or Issuers*
Microsoft Corp. 9.4%
Amazon.com, Inc. 6.8%
NVIDIA Corp. 6.4%
Apple, Inc. 5.6%
Meta Platforms, Inc., Class A 5.0%
Broadcom, Inc. 4.2%
Eli Lilly & Co. 4.1%
Visa, Inc., Class A 3.2%
Netflix, Inc. 3.0%
Spotify Technology SA 2.9%
* Excluding short-term investments
C000018729 [Member]  
Shareholder Report [Line Items]  
Fund Name NYLI Winslow Large Cap Growth Fund
Class Name Class R2
Trading Symbol MLRTX
Annual or Semi-Annual Statement [Text Block] This semiannual shareholder report contains important information about NYLI Winslow Large Cap Growth Fund (the "Fund") for the period November 1, 2024 to April 30, 2025.
Shareholder Report Annual or Semi-Annual semi-annual shareholder report
Additional Information [Text Block] You can find additional information about the Fund at dfinview.com/NYLIM. You can also request this information by contacting us at 800-624-6782.
Additional Information Phone Number 800-624-6782
Additional Information Website dfinview.com/NYLIM
Expenses [Text Block]
What were the Fund costs for the last six months?
(Based on a hypothetical $10,000 investment)
Share Class Name Costs of a $10,000 investment Costs paid as a percentage
of a $10,000 investment1,2
Class R2 $51 1.04%
1.
Reflects fee waivers and/or expense reimbursements, without which expenses would have been higher.
2.
Annualized.
Expenses Paid, Amount $ 51
Expense Ratio, Percent 1.04% [72],[73]
Performance Past Does Not Indicate Future [Text] Keep in mind that the Fund ’s past performance is not a good predictor of how the Fund will perform in the future.
Line Graph [Table Text Block]
Fund Performance
The following graph compares the initial and subsequent account values at the end of each of the most recently completed 10 semiannual reporting periods of the Fund (or for the life of the Fund, if shorter). It assumes a $10,000 initial investment at the beginning of the first fiscal period in an appropriate, broad-based securities market index and other additional indexes, if applicable, for the same period and reflects the deduction of all sales charges, where applicable.
Fund Performance - Growth of 10K
Average Annual Return [Table Text Block]
Average Annual Total Returns for the Period Ended April 30, 2025 Inception
Date		 Six
Months1		 One
Year		 Five
Years		 Ten
Years
Class R2 Shares 4/1/2005 (0.84)% 13.10% 15.16% 13.89%
Russell 3000®Index2 (2.15)% 11.40% 15.12% 11.68%
Russell 1000® Growth Index3 (1.57)% 14.53% 17.23% 15.27%
S&P 500®Index4 (1.74)% 12.10% 15.61% 12.32%
Morningstar Large Growth Category Average5 (1.64)% 12.32% 14.18% 12.78%
1.
Not annualized.
2.
The Fund has selected the Russell 3000® Index to represent a broad measure of market performance. The Russell 3000® Index measures the performance of the largest 3,000 U.S. companies representing approximately 98% of the investable U.S. equity market.
3.
The Russell 1000® Growth Index, which is generally representative of the market sectors or types of investments in which the Fund invests, measures the performance of the large-cap growth segment of the U.S. equity universe. It includes those Russell 1000® Index companies with higher price-to-book ratios and higher forecasted growth values.
4.
The S&P 500® Index, which represents a broad measure of market performance, is generally representative of the market sectors or types of investments in which the Fund invests. S&P® and S&P 500® are registered trademarks of Standard & Poor’s Financial Services LLC. The S&P 500® Index is widely regarded as the standard index for measuring large-cap U.S. stock market performance.
5.
The Morningstar Large Growth Category Average is representative of funds that invest primarily in big U.S. companies that are projected to grow faster than other large-cap stocks. Stocks in the top 70% of the capitalization of the U.S. equity market are defined as large cap. Growth is defined based on fast growth and high valuations. Most of these funds focus on companies in rapidly expanding industries. Results are based on average total returns of similar funds with all dividends and capital gain distributions reinvested.
Performance Inception Date Apr. 01, 2005
No Deduction of Taxes [Text Block] The graph and table do not reflect the deduction of taxes that a shareholder would pay on Fund distributions or redemption of Fund shares.
Updated Performance Information Location [Text Block] Visit newyorklifeinvestments.com/funds for the most recent performance information.
Net Assets $ 12,360,651,183
Holdings Count | Holding 44
Investment Company Portfolio Turnover 42.00%
Additional Fund Statistics [Text Block]
Key Fund Statistics
Fund's net assets $12,360,651,183%
Total number of portfolio holdings 44%
Portfolio turnover rate 42%
Holdings [Text Block]
Graphical Representation of Holdings
The tables below show the investment makeup of the Fund; percentages indicated are based on the Fund's net assets.
Top Ten Holdings and/or Issuers*
Microsoft Corp. 9.4%
Amazon.com, Inc. 6.8%
NVIDIA Corp. 6.4%
Apple, Inc. 5.6%
Meta Platforms, Inc., Class A 5.0%
Broadcom, Inc. 4.2%
Eli Lilly & Co. 4.1%
Visa, Inc., Class A 3.2%
Netflix, Inc. 3.0%
Spotify Technology SA 2.9%
* Excluding short-term investments
Top Industries 
Software 17.3%
Semiconductors & Semiconductor Equipment 13.9%
Interactive Media & Services 7.6%
Financial Services 7.2%
Broadline Retail 6.8%
Hotels, Restaurants & Leisure 6.3%
Entertainment 5.9%
Technology Hardware, Storage & Peripherals 5.6%
Health Care Equipment & Supplies 5.4%
Aerospace & Defense 4.6%
Largest Holdings [Text Block]
Top Ten Holdings and/or Issuers*
Microsoft Corp. 9.4%
Amazon.com, Inc. 6.8%
NVIDIA Corp. 6.4%
Apple, Inc. 5.6%
Meta Platforms, Inc., Class A 5.0%
Broadcom, Inc. 4.2%
Eli Lilly & Co. 4.1%
Visa, Inc., Class A 3.2%
Netflix, Inc. 3.0%
Spotify Technology SA 2.9%
* Excluding short-term investments
C000030958 [Member]  
Shareholder Report [Line Items]  
Fund Name NYLI Winslow Large Cap Growth Fund
Class Name Class R3
Trading Symbol MLGRX
Annual or Semi-Annual Statement [Text Block] This semiannual shareholder report contains important information about NYLI Winslow Large Cap Growth Fund (the "Fund") for the period November 1, 2024 to April 30, 2025.
Shareholder Report Annual or Semi-Annual semi-annual shareholder report
Additional Information [Text Block] You can find additional information about the Fund at dfinview.com/NYLIM. You can also request this information by contacting us at 800-624-6782.
Additional Information Phone Number 800-624-6782
Additional Information Website dfinview.com/NYLIM
Expenses [Text Block]
What were the Fund costs for the last six months?
(Based on a hypothetical $10,000 investment)
Share Class Name Costs of a $10,000 investment Costs paid as a percentage
of a $10,000 investment1,2
Class R3 $64 1.29%
1.
Reflects fee waivers and/or expense reimbursements, without which expenses would have been higher.
2.
Annualized.
Expenses Paid, Amount $ 64
Expense Ratio, Percent 1.29% [74],[75]
Performance Past Does Not Indicate Future [Text] Keep in mind that the Fund ’s past performance is not a good predictor of how the Fund will perform in the future.
Line Graph [Table Text Block]
Fund Performance
The following graph compares the initial and subsequent account values at the end of each of the most recently completed 10 semiannual reporting periods of the Fund (or for the life of the Fund, if shorter). It assumes a $10,000 initial investment at the beginning of the first fiscal period in an appropriate, broad-based securities market index and other additional indexes, if applicable, for the same period and reflects the deduction of all sales charges, where applicable.
Fund Performance - Growth of 10K
Average Annual Return [Table Text Block]
Average Annual Total Returns for the Period Ended April 30, 2025 Inception
Date		 Six
Months1		 One
Year		 Five
Years		 Ten
Years
Class R3 Shares 4/28/2006 (1.01)% 12.67% 14.85% 13.60%
Russell 3000®Index2 (2.15)% 11.40% 15.12% 11.68%
Russell 1000® Growth Index3 (1.57)% 14.53% 17.23% 15.27%
S&P 500®Index4 (1.74)% 12.10% 15.61% 12.32%
Morningstar Large Growth Category Average5 (1.64)% 12.32% 14.18% 12.78%
1.
Not annualized.
2.
The Fund has selected the Russell 3000® Index to represent a broad measure of market performance. The Russell 3000® Index measures the performance of the largest 3,000 U.S. companies representing approximately 98% of the investable U.S. equity market.
3.
The Russell 1000® Growth Index, which is generally representative of the market sectors or types of investments in which the Fund invests, measures the performance of the large-cap growth segment of the U.S. equity universe. It includes those Russell 1000® Index companies with higher price-to-book ratios and higher forecasted growth values.
4.
The S&P 500® Index, which represents a broad measure of market performance, is generally representative of the market sectors or types of investments in which the Fund invests. S&P® and S&P 500® are registered trademarks of Standard & Poor’s Financial Services LLC. The S&P 500® Index is widely regarded as the standard index for measuring large-cap U.S. stock market performance.
5.
The Morningstar Large Growth Category Average is representative of funds that invest primarily in big U.S. companies that are projected to grow faster than other large-cap stocks. Stocks in the top 70% of the capitalization of the U.S. equity market are defined as large cap. Growth is defined based on fast growth and high valuations. Most of these funds focus on companies in rapidly expanding industries. Results are based on average total returns of similar funds with all dividends and capital gain distributions reinvested.
Performance Inception Date Apr. 28, 2006
No Deduction of Taxes [Text Block] The graph and table do not reflect the deduction of taxes that a shareholder would pay on Fund distributions or redemption of Fund shares.
Updated Performance Information Location [Text Block] Visit newyorklifeinvestments.com/funds for the most recent performance information.
Net Assets $ 12,360,651,183
Holdings Count | Holding 44
Investment Company Portfolio Turnover 42.00%
Additional Fund Statistics [Text Block]
Key Fund Statistics
Fund's net assets $12,360,651,183%
Total number of portfolio holdings 44%
Portfolio turnover rate 42%
Holdings [Text Block]
Graphical Representation of Holdings
The tables below show the investment makeup of the Fund; percentages indicated are based on the Fund's net assets.
Top Ten Holdings and/or Issuers*
Microsoft Corp. 9.4%
Amazon.com, Inc. 6.8%
NVIDIA Corp. 6.4%
Apple, Inc. 5.6%
Meta Platforms, Inc., Class A 5.0%
Broadcom, Inc. 4.2%
Eli Lilly & Co. 4.1%
Visa, Inc., Class A 3.2%
Netflix, Inc. 3.0%
Spotify Technology SA 2.9%
* Excluding short-term investments
Top Industries 
Software 17.3%
Semiconductors & Semiconductor Equipment 13.9%
Interactive Media & Services 7.6%
Financial Services 7.2%
Broadline Retail 6.8%
Hotels, Restaurants & Leisure 6.3%
Entertainment 5.9%
Technology Hardware, Storage & Peripherals 5.6%
Health Care Equipment & Supplies 5.4%
Aerospace & Defense 4.6%
Largest Holdings [Text Block]
Top Ten Holdings and/or Issuers*
Microsoft Corp. 9.4%
Amazon.com, Inc. 6.8%
NVIDIA Corp. 6.4%
Apple, Inc. 5.6%
Meta Platforms, Inc., Class A 5.0%
Broadcom, Inc. 4.2%
Eli Lilly & Co. 4.1%
Visa, Inc., Class A 3.2%
Netflix, Inc. 3.0%
Spotify Technology SA 2.9%
* Excluding short-term investments
C000127162 [Member]  
Shareholder Report [Line Items]  
Fund Name NYLI Winslow Large Cap Growth Fund
Class Name Class R6
Trading Symbol MLRSX
Annual or Semi-Annual Statement [Text Block] This semiannual shareholder report contains important information about NYLI Winslow Large Cap Growth Fund (the "Fund") for the period November 1, 2024 to April 30, 2025.
Shareholder Report Annual or Semi-Annual semi-annual shareholder report
Additional Information [Text Block] You can find additional information about the Fund at dfinview.com/NYLIM. You can also request this information by contacting us at 800-624-6782.
Additional Information Phone Number 800-624-6782
Additional Information Website dfinview.com/NYLIM
Expenses [Text Block]
What were the Fund costs for the last six months?
(Based on a hypothetical $10,000 investment)
Share Class Name Costs of a $10,000 investment Costs paid as a percentage
of a $10,000 investment1,2
Class R6 $31 0.63%
1.
Reflects fee waivers and/or expense reimbursements, without which expenses would have been higher.
2.
Annualized.
Expenses Paid, Amount $ 31
Expense Ratio, Percent 0.63% [76],[77]
Performance Past Does Not Indicate Future [Text] Keep in mind that the Fund ’s past performance is not a good predictor of how the Fund will perform in the future.
Line Graph [Table Text Block]
Fund Performance
The following graph compares the initial and subsequent account values at the end of each of the most recently completed 10 semiannual reporting periods of the Fund (or for the life of the Fund, if shorter). It assumes a $10,000 initial investment at the beginning of the first fiscal period in an appropriate, broad-based securities market index and other additional indexes, if applicable, for the same period and reflects the deduction of all sales charges, where applicable.
Fund Performance - Growth of 10K
Average Annual Return [Table Text Block]
Average Annual Total Returns for the Period Ended April 30, 2025 Inception
Date		 Six
Months1		 One
Year		 Five
Years		 Ten
Years
Class R6 Shares 6/17/2013 (0.65)% 13.50% 15.63% 14.39%
Russell 3000®Index2 (2.15)% 11.40% 15.12% 11.68%
Russell 1000® Growth Index3 (1.57)% 14.53% 17.23% 15.27%
S&P 500®Index4 (1.74)% 12.10% 15.61% 12.32%
Morningstar Large Growth Category Average5 (1.64)% 12.32% 14.18% 12.78%
1.
Not annualized.
2.
The Fund has selected the Russell 3000® Index to represent a broad measure of market performance. The Russell 3000® Index measures the performance of the largest 3,000 U.S. companies representing approximately 98% of the investable U.S. equity market.
3.
The Russell 1000® Growth Index, which is generally representative of the market sectors or types of investments in which the Fund invests, measures the performance of the large-cap growth segment of the U.S. equity universe. It includes those Russell 1000® Index companies with higher price-to-book ratios and higher forecasted growth values.
4.
The S&P 500® Index, which represents a broad measure of market performance, is generally representative of the market sectors or types of investments in which the Fund invests. S&P® and S&P 500® are registered trademarks of Standard & Poor’s Financial Services LLC. The S&P 500® Index is widely regarded as the standard index for measuring large-cap U.S. stock market performance.
5.
The Morningstar Large Growth Category Average is representative of funds that invest primarily in big U.S. companies that are projected to grow faster than other large-cap stocks. Stocks in the top 70% of the capitalization of the U.S. equity market are defined as large cap. Growth is defined based on fast growth and high valuations. Most of these funds focus on companies in rapidly expanding industries. Results are based on average total returns of similar funds with all dividends and capital gain distributions reinvested.
Performance Inception Date Jun. 17, 2013
No Deduction of Taxes [Text Block] The graph and table do not reflect the deduction of taxes that a shareholder would pay on Fund distributions or redemption of Fund shares.
Updated Performance Information Location [Text Block] Visit newyorklifeinvestments.com/funds for the most recent performance information.
Net Assets $ 12,360,651,183
Holdings Count | Holding 44
Investment Company Portfolio Turnover 42.00%
Additional Fund Statistics [Text Block]
Key Fund Statistics
Fund's net assets $12,360,651,183%
Total number of portfolio holdings 44%
Portfolio turnover rate 42%
Holdings [Text Block]
Graphical Representation of Holdings
The tables below show the investment makeup of the Fund; percentages indicated are based on the Fund's net assets.
Top Ten Holdings and/or Issuers*
Microsoft Corp. 9.4%
Amazon.com, Inc. 6.8%
NVIDIA Corp. 6.4%
Apple, Inc. 5.6%
Meta Platforms, Inc., Class A 5.0%
Broadcom, Inc. 4.2%
Eli Lilly & Co. 4.1%
Visa, Inc., Class A 3.2%
Netflix, Inc. 3.0%
Spotify Technology SA 2.9%
* Excluding short-term investments
Top Industries 
Software 17.3%
Semiconductors & Semiconductor Equipment 13.9%
Interactive Media & Services 7.6%
Financial Services 7.2%
Broadline Retail 6.8%
Hotels, Restaurants & Leisure 6.3%
Entertainment 5.9%
Technology Hardware, Storage & Peripherals 5.6%
Health Care Equipment & Supplies 5.4%
Aerospace & Defense 4.6%
Largest Holdings [Text Block]
Top Ten Holdings and/or Issuers*
Microsoft Corp. 9.4%
Amazon.com, Inc. 6.8%
NVIDIA Corp. 6.4%
Apple, Inc. 5.6%
Meta Platforms, Inc., Class A 5.0%
Broadcom, Inc. 4.2%
Eli Lilly & Co. 4.1%
Visa, Inc., Class A 3.2%
Netflix, Inc. 3.0%
Spotify Technology SA 2.9%
* Excluding short-term investments
C000060800 [Member]  
Shareholder Report [Line Items]  
Fund Name NYLI Winslow Large Cap Growth Fund
Class Name Investor Class
Trading Symbol MLINX
Annual or Semi-Annual Statement [Text Block] This semiannual shareholder report contains important information about NYLI Winslow Large Cap Growth Fund (the "Fund") for the period November 1, 2024 to April 30, 2025.
Shareholder Report Annual or Semi-Annual semi-annual shareholder report
Additional Information [Text Block] You can find additional information about the Fund at dfinview.com/NYLIM. You can also request this information by contacting us at 800-624-6782.
Additional Information Phone Number 800-624-6782
Additional Information Website dfinview.com/NYLIM
Expenses [Text Block]
What were the Fund costs for the last six months?
(Based on a hypothetical $10,000 investment)
Share Class Name Costs of a $10,000 investment Costs paid as a percentage
of a $10,000 investment1,2
Investor Class $55 1.12%
1.
Reflects fee waivers and/or expense reimbursements, without which expenses would have been higher.
2.
Annualized.
Expenses Paid, Amount $ 55
Expense Ratio, Percent 1.12% [78],[79]
Performance Past Does Not Indicate Future [Text] Keep in mind that the Fund ’s past performance is not a good predictor of how the Fund will perform in the future.
Line Graph [Table Text Block]
Fund Performance
The following graph compares the initial and subsequent account values at the end of each of the most recently completed 10 semiannual reporting periods of the Fund (or for the life of the Fund, if shorter). It assumes a $10,000 initial investment at the beginning of the first fiscal period in an appropriate, broad-based securities market index and other additional indexes, if applicable, for the same period and reflects the deduction of all sales charges, where applicable.
Fund Performance - Growth of 10K
Average Annual Return [Table Text Block]
Average Annual Total Returns for the Period Ended April 30, 2025 Inception
Date		 Six
Months1		 One
Year		 Five
Years		 Ten
Years
Investor Class Shares - Including sales charges 2/28/2008 (5.82)% 7.36% 13.77% 13.23%
Investor Class Shares - Excluding sales charges (0.86)% 13.01% 15.06% 13.87%
Russell 3000®Index2 (2.15)% 11.40% 15.12% 11.68%
Russell 1000® Growth Index3 (1.57)% 14.53% 17.23% 15.27%
S&P 500®Index4 (1.74)% 12.10% 15.61% 12.32%
Morningstar Large Growth Category Average5 (1.64)% 12.32% 14.18% 12.78%
1.
Not annualized.
2.
The Fund has selected the Russell 3000® Index to represent a broad measure of market performance. The Russell 3000® Index measures the performance of the largest 3,000 U.S. companies representing approximately 98% of the investable U.S. equity market.
3.
The Russell 1000® Growth Index, which is generally representative of the market sectors or types of investments in which the Fund invests, measures the performance of the large-cap growth segment of the U.S. equity universe. It includes those Russell 1000® Index companies with higher price-to-book ratios and higher forecasted growth values.
4.
The S&P 500® Index, which represents a broad measure of market performance, is generally representative of the market sectors or types of investments in which the Fund invests. S&P® and S&P 500® are registered trademarks of Standard & Poor’s Financial Services LLC. The S&P 500® Index is widely regarded as the standard index for measuring large-cap U.S. stock market performance.
5.
The Morningstar Large Growth Category Average is representative of funds that invest primarily in big U.S. companies that are projected to grow faster than other large-cap stocks. Stocks in the top 70% of the capitalization of the U.S. equity market are defined as large cap. Growth is defined based on fast growth and high valuations. Most of these funds focus on companies in rapidly expanding industries. Results are based on average total returns of similar funds with all dividends and capital gain distributions reinvested.
Performance Inception Date Feb. 28, 2008
No Deduction of Taxes [Text Block] The graph and table do not reflect the deduction of taxes that a shareholder would pay on Fund distributions or redemption of Fund shares.
Updated Performance Information Location [Text Block] Visit newyorklifeinvestments.com/funds for the most recent performance information.
Net Assets $ 12,360,651,183
Holdings Count | Holding 44
Investment Company Portfolio Turnover 42.00%
Additional Fund Statistics [Text Block]
Key Fund Statistics
Fund's net assets $12,360,651,183%
Total number of portfolio holdings 44%
Portfolio turnover rate 42%
Holdings [Text Block]
Graphical Representation of Holdings
The tables below show the investment makeup of the Fund; percentages indicated are based on the Fund's net assets.
Top Ten Holdings and/or Issuers*
Microsoft Corp. 9.4%
Amazon.com, Inc. 6.8%
NVIDIA Corp. 6.4%
Apple, Inc. 5.6%
Meta Platforms, Inc., Class A 5.0%
Broadcom, Inc. 4.2%
Eli Lilly & Co. 4.1%
Visa, Inc., Class A 3.2%
Netflix, Inc. 3.0%
Spotify Technology SA 2.9%
* Excluding short-term investments
Top Industries 
Software 17.3%
Semiconductors & Semiconductor Equipment 13.9%
Interactive Media & Services 7.6%
Financial Services 7.2%
Broadline Retail 6.8%
Hotels, Restaurants & Leisure 6.3%
Entertainment 5.9%
Technology Hardware, Storage & Peripherals 5.6%
Health Care Equipment & Supplies 5.4%
Aerospace & Defense 4.6%
Largest Holdings [Text Block]
Top Ten Holdings and/or Issuers*
Microsoft Corp. 9.4%
Amazon.com, Inc. 6.8%
NVIDIA Corp. 6.4%
Apple, Inc. 5.6%
Meta Platforms, Inc., Class A 5.0%
Broadcom, Inc. 4.2%
Eli Lilly & Co. 4.1%
Visa, Inc., Class A 3.2%
Netflix, Inc. 3.0%
Spotify Technology SA 2.9%
* Excluding short-term investments
C000221700 [Member]  
Shareholder Report [Line Items]  
Fund Name NYLI Winslow Large Cap Growth Fund
Class Name SIMPLE Class
Trading Symbol MLRMX
Annual or Semi-Annual Statement [Text Block] This semiannual shareholder report contains important information about NYLI Winslow Large Cap Growth Fund (the "Fund") for the period November 1, 2024 to April 30, 2025.
Shareholder Report Annual or Semi-Annual semi-annual shareholder report
Additional Information [Text Block] You can find additional information about the Fund at dfinview.com/NYLIM. You can also request this information by contacting us at 800-624-6782.
Additional Information Phone Number 800-624-6782
Additional Information Website dfinview.com/NYLIM
Expenses [Text Block]
What were the Fund costs for the last six months?
(Based on a hypothetical $10,000 investment)
Share Class Name Costs of a $10,000 investment Costs paid as a percentage
of a $10,000 investment1,2
SIMPLE Class $58 1.18%
1.
Reflects fee waivers and/or expense reimbursements, without which expenses would have been higher.
2.
Annualized.
Expenses Paid, Amount $ 58
Expense Ratio, Percent 1.18% [80],[81]
Performance Past Does Not Indicate Future [Text] Keep in mind that the Fund ’s past performance is not a good predictor of how the Fund will perform in the future.
Line Graph [Table Text Block]
Fund Performance
The following graph compares the initial and subsequent account values at the end of each of the most recently completed 10 semiannual reporting periods of the Fund (or for the life of the Fund, if shorter). It assumes a $10,000 initial investment at the beginning of the first fiscal period in an appropriate, broad-based securities market index and other additional indexes, if applicable, for the same period and reflects the deduction of all sales charges, where applicable.
Fund Performance - Growth of 10K
Average Annual Return [Table Text Block]
Average Annual Total Returns for the Period Ended April 30, 2025 Inception
Date		 Six
Months1		 One
Year		 Since
Inception
SIMPLE Class Shares 8/31/2020 (0.99)% 12.78% 9.28%
Russell 3000®Index2 (2.15)% 11.40% 11.41%
Russell 1000® Growth Index3 (1.57)% 14.53% 11.66%
S&P 500®Index4 (1.74)% 12.10% 12.14%
Morningstar Large Growth Category Average5 (1.64)% 12.32% 8.71%
1.
Not annualized.
2.
The Fund has selected the Russell 3000® Index to represent a broad measure of market performance. The Russell 3000® Index measures the performance of the largest 3,000 U.S. companies representing approximately 98% of the investable U.S. equity market.
3.
The Russell 1000® Growth Index, which is generally representative of the market sectors or types of investments in which the Fund invests, measures the performance of the large-cap growth segment of the U.S. equity universe. It includes those Russell 1000® Index companies with higher price-to-book ratios and higher forecasted growth values.
4.
The S&P 500® Index, which represents a broad measure of market performance, is generally representative of the market sectors or types of investments in which the Fund invests. S&P® and S&P 500® are registered trademarks of Standard & Poor’s Financial Services LLC. The S&P 500® Index is widely regarded as the standard index for measuring large-cap U.S. stock market performance.
5.
The Morningstar Large Growth Category Average is representative of funds that invest primarily in big U.S. companies that are projected to grow faster than other large-cap stocks. Stocks in the top 70% of the capitalization of the U.S. equity market are defined as large cap. Growth is defined based on fast growth and high valuations. Most of these funds focus on companies in rapidly expanding industries. Results are based on average total returns of similar funds with all dividends and capital gain distributions reinvested.
Performance Inception Date Aug. 31, 2020
No Deduction of Taxes [Text Block] The graph and table do not reflect the deduction of taxes that a shareholder would pay on Fund distributions or redemption of Fund shares.
Updated Performance Information Location [Text Block] Visit newyorklifeinvestments.com/funds for the most recent performance information.
Net Assets $ 12,360,651,183
Holdings Count | Holding 44
Investment Company Portfolio Turnover 42.00%
Additional Fund Statistics [Text Block]
Key Fund Statistics
Fund's net assets $12,360,651,183%
Total number of portfolio holdings 44%
Portfolio turnover rate 42%
Holdings [Text Block]
Graphical Representation of Holdings
The tables below show the investment makeup of the Fund; percentages indicated are based on the Fund's net assets.
Top Ten Holdings and/or Issuers*
Microsoft Corp. 9.4%
Amazon.com, Inc. 6.8%
NVIDIA Corp. 6.4%
Apple, Inc. 5.6%
Meta Platforms, Inc., Class A 5.0%
Broadcom, Inc. 4.2%
Eli Lilly & Co. 4.1%
Visa, Inc., Class A 3.2%
Netflix, Inc. 3.0%
Spotify Technology SA 2.9%
* Excluding short-term investments
Top Industries 
Software 17.3%
Semiconductors & Semiconductor Equipment 13.9%
Interactive Media & Services 7.6%
Financial Services 7.2%
Broadline Retail 6.8%
Hotels, Restaurants & Leisure 6.3%
Entertainment 5.9%
Technology Hardware, Storage & Peripherals 5.6%
Health Care Equipment & Supplies 5.4%
Aerospace & Defense 4.6%
Largest Holdings [Text Block]
Top Ten Holdings and/or Issuers*
Microsoft Corp. 9.4%
Amazon.com, Inc. 6.8%
NVIDIA Corp. 6.4%
Apple, Inc. 5.6%
Meta Platforms, Inc., Class A 5.0%
Broadcom, Inc. 4.2%
Eli Lilly & Co. 4.1%
Visa, Inc., Class A 3.2%
Netflix, Inc. 3.0%
Spotify Technology SA 2.9%
* Excluding short-term investments
C000018730 [Member]  
Shareholder Report [Line Items]  
Fund Name NYLI WMC Value Fund
Class Name Class A
Trading Symbol MAPAX
Annual or Semi-Annual Statement [Text Block] This semiannual shareholder report contains important information about NYLI WMC Value Fund (the "Fund") for the period November 1, 2024 to April 30, 2025.
Shareholder Report Annual or Semi-Annual semi-annual shareholder report
Additional Information [Text Block] You can find additional information about the Fund at dfinview.com/NYLIM. You can also request this information by contacting us at 800-624-6782.
Additional Information Phone Number 800-624-6782
Additional Information Website dfinview.com/NYLIM
Expenses [Text Block]
What were the Fund costs for the last six months?
(Based on a hypothetical $10,000 investment)
Share Class Name Costs of a $10,000 investment Costs paid as a percentage
of a $10,000 investment1
Class A $50 1.01%
1.
Annualized.
Expenses Paid, Amount $ 50
Expense Ratio, Percent 1.01% [82]
Performance Past Does Not Indicate Future [Text] Keep in mind that the Fund ’s past performance is not a good predictor of how the Fund will perform in the future.
Line Graph [Table Text Block]
Fund Performance
The following graph compares the initial and subsequent account values at the end of each of the most recently completed 10 semiannual reporting periods of the Fund (or for the life of the Fund, if shorter). It assumes a $15,000 initial investment at the beginning of the first fiscal period in an appropriate, broad-based securities market index and other additional indexes, if applicable, for the same period and reflects the deduction of all sales charges, where applicable. One of the Fund's subadvisors changed effective January 9, 2017, and the Fund's principal investment strategies changed effective February 28, 2017 and March 13, 2017. Effective April 26, 2021, the Fund replaced both of its subadvisors and modified its principal investment strategies. The past performance in the graph and table prior to that date reflects the Fund’s prior subadvisors and principal investment strategies.
Fund Performance - Growth of 10K
Average Annual Return [Table Text Block]
Average Annual Total Returns for the Period Ended April 30, 2025 Inception
Date		 Six
Months1		 One
Year		 Five
Years		 Ten
Years
Class A Shares - Including sales charges 6/9/1999 (7.94)% 1.93% 12.88% 8.87%
Class A Shares - Excluding sales charges (2.58)% 7.86% 14.16% 9.49%
Russell 3000®Index2 (2.15)% 11.40% 15.12% 11.68%
Russell 1000® Value Index3 (1.86)% 8.55% 13.00% 8.36%
Morningstar Large Value Category Average4 (2.27)% 7.57% 13.36% 8.45%
1.
Not annualized.
2.
The Fund has selected the Russell 3000® Index to represent a broad measure of market performance. The Russell 3000® Index measures the performance of the largest 3,000 U.S. companies representing approximately 98% of the investable U.S. equity market.
3.
The Russell 1000® Value Index, which is generally representative of the market sectors or types of investments in which the Fund invests, 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.
4.
The Morningstar Large Value Category Average is representative of funds that invest primarily in big U.S. companies that are less expensive or growing more slowly than other large-cap stocks. Results are based on average total returns of similar funds with all dividends and capital gain distributions reinvested.
Performance Inception Date Jun. 09, 1999
No Deduction of Taxes [Text Block] The graph and table do not reflect the deduction of taxes that a shareholder would pay on Fund distributions or redemption of Fund shares.
Updated Performance Information Location [Text Block] Visit newyorklifeinvestments.com/funds for the most recent performance information.
Net Assets $ 920,939,860
Holdings Count | Holding 68
Investment Company Portfolio Turnover 21.00%
Additional Fund Statistics [Text Block]
Key Fund Statistics
Fund's net assets $920,939,860%
Total number of portfolio holdings 68%
Portfolio turnover rate 21%
Holdings [Text Block]
Graphical Representation of Holdings
The tables below show the investment makeup of the Fund; percentages indicated are based on the Fund's net assets.
Top Ten Holdings and/or Issuers*
JPMorgan Chase & Co. 3.9%
Johnson & Johnson 3.2%
UnitedHealth Group, Inc. 2.7%
Cisco Systems, Inc. 2.4%
Gilead Sciences, Inc. 2.1%
American International Group, Inc. 2.1%
Pfizer, Inc. 1.9%
Johnson Controls International plc 1.9%
Elevance Health, Inc. 1.9%
Marsh & McLennan Cos., Inc. 1.8%
* Excluding short-term investments
Top Industries 
Pharmaceuticals 9.2%
Oil, Gas & Consumable Fuels 9.1%
Capital Markets 8.2%
Banks 7.9%
Insurance 6.8%
Health Care Providers & Services 6.3%
Communications Equipment 3.6%
Multi–Utilities 3.3%
Specialized REITs 3.1%
Machinery 2.8%
Largest Holdings [Text Block]
Top Ten Holdings and/or Issuers*
JPMorgan Chase & Co. 3.9%
Johnson & Johnson 3.2%
UnitedHealth Group, Inc. 2.7%
Cisco Systems, Inc. 2.4%
Gilead Sciences, Inc. 2.1%
American International Group, Inc. 2.1%
Pfizer, Inc. 1.9%
Johnson Controls International plc 1.9%
Elevance Health, Inc. 1.9%
Marsh & McLennan Cos., Inc. 1.8%
* Excluding short-term investments
C000018732 [Member]  
Shareholder Report [Line Items]  
Fund Name NYLI WMC Value Fund
Class Name Class C
Trading Symbol MMPCX
Annual or Semi-Annual Statement [Text Block] This semiannual shareholder report contains important information about NYLI WMC Value Fund (the "Fund") for the period November 1, 2024 to April 30, 2025.
Shareholder Report Annual or Semi-Annual semi-annual shareholder report
Additional Information [Text Block] You can find additional information about the Fund at dfinview.com/NYLIM. You can also request this information by contacting us at 800-624-6782.
Additional Information Phone Number 800-624-6782
Additional Information Website dfinview.com/NYLIM
Expenses [Text Block]
What were the Fund costs for the last six months?
(Based on a hypothetical $10,000 investment)
Share Class Name Costs of a $10,000 investment Costs paid as a percentage
of a $10,000 investment1
Class C $98 2.00%
1.
Annualized.
Expenses Paid, Amount $ 98
Expense Ratio, Percent 2.00% [83]
Performance Past Does Not Indicate Future [Text] Keep in mind that the Fund ’s past performance is not a good predictor of how the Fund will perform in the future.
Line Graph [Table Text Block]
Fund Performance
The following graph compares the initial and subsequent account values at the end of each of the most recently completed 10 semiannual reporting periods of the Fund (or for the life of the Fund, if shorter). It assumes a $10,000 initial investment at the beginning of the first fiscal period in an appropriate, broad-based securities market index and other additional indexes, if applicable, for the same period and reflects the deduction of all sales charges, where applicable. One of the Fund's subadvisors changed effective January 9, 2017, and the Fund's principal investment strategies changed effective February 28, 2017 and March 13, 2017. Effective April 26, 2021, the Fund replaced both of its subadvisors and modified its principal investment strategies. The past performance in the graph and table prior to that date reflects the Fund’s prior subadvisors and principal investment strategies.
Fund Performance - Growth of 10K
Average Annual Return [Table Text Block]
Average Annual Total Returns for the Period Ended April 30, 2025 Inception
Date		 Six
Months1		 One
Year		 Five
Years		 Ten
Years
Class C Shares - Including sales charges 6/9/1999 (3.95)% 5.80% 13.02% 8.42%
Class C Shares - Excluding sales charges (3.05)% 6.80% 13.02% 8.42%
Russell 3000®Index2 (2.15)% 11.40% 15.12% 11.68%
Russell 1000® Value Index3 (1.86)% 8.55% 13.00% 8.36%
Morningstar Large Value Category Average4 (2.27)% 7.57% 13.36% 8.45%
1.
Not annualized.
2.
The Fund has selected the Russell 3000® Index to represent a broad measure of market performance. The Russell 3000® Index measures the performance of the largest 3,000 U.S. companies representing approximately 98% of the investable U.S. equity market.
3.
The Russell 1000® Value Index, which is generally representative of the market sectors or types of investments in which the Fund invests, 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.
4.
The Morningstar Large Value Category Average is representative of funds that invest primarily in big U.S. companies that are less expensive or growing more slowly than other large-cap stocks. Results are based on average total returns of similar funds with all dividends and capital gain distributions reinvested.
Performance Inception Date Jun. 09, 1999
No Deduction of Taxes [Text Block] The graph and table do not reflect the deduction of taxes that a shareholder would pay on Fund distributions or redemption of Fund shares.
Updated Performance Information Location [Text Block] Visit newyorklifeinvestments.com/funds for the most recent performance information.
Net Assets $ 920,939,860
Holdings Count | Holding 68
Investment Company Portfolio Turnover 21.00%
Additional Fund Statistics [Text Block]
Key Fund Statistics
Fund's net assets $920,939,860%
Total number of portfolio holdings 68%
Portfolio turnover rate 21%
Holdings [Text Block]
Graphical Representation of Holdings
The tables below show the investment makeup of the Fund; percentages indicated are based on the Fund's net assets.
Top Ten Holdings and/or Issuers*
JPMorgan Chase & Co. 3.9%
Johnson & Johnson 3.2%
UnitedHealth Group, Inc. 2.7%
Cisco Systems, Inc. 2.4%
Gilead Sciences, Inc. 2.1%
American International Group, Inc. 2.1%
Pfizer, Inc. 1.9%
Johnson Controls International plc 1.9%
Elevance Health, Inc. 1.9%
Marsh & McLennan Cos., Inc. 1.8%
* Excluding short-term investments
Top Industries 
Pharmaceuticals 9.2%
Oil, Gas & Consumable Fuels 9.1%
Capital Markets 8.2%
Banks 7.9%
Insurance 6.8%
Health Care Providers & Services 6.3%
Communications Equipment 3.6%
Multi–Utilities 3.3%
Specialized REITs 3.1%
Machinery 2.8%
Largest Holdings [Text Block]
Top Ten Holdings and/or Issuers*
JPMorgan Chase & Co. 3.9%
Johnson & Johnson 3.2%
UnitedHealth Group, Inc. 2.7%
Cisco Systems, Inc. 2.4%
Gilead Sciences, Inc. 2.1%
American International Group, Inc. 2.1%
Pfizer, Inc. 1.9%
Johnson Controls International plc 1.9%
Elevance Health, Inc. 1.9%
Marsh & McLennan Cos., Inc. 1.8%
* Excluding short-term investments
C000018733 [Member]  
Shareholder Report [Line Items]  
Fund Name NYLI WMC Value Fund
Class Name Class I
Trading Symbol MUBFX
Annual or Semi-Annual Statement [Text Block] This semiannual shareholder report contains important information about NYLI WMC Value Fund (the "Fund") for the period November 1, 2024 to April 30, 2025.
Shareholder Report Annual or Semi-Annual semi-annual shareholder report
Additional Information [Text Block] You can find additional information about the Fund at dfinview.com/NYLIM. You can also request this information by contacting us at 800-624-6782.
Additional Information Phone Number 800-624-6782
Additional Information Website dfinview.com/NYLIM
Expenses [Text Block]
What were the Fund costs for the last six months?
(Based on a hypothetical $10,000 investment)
Share Class Name Costs of a $10,000 investment Costs paid as a percentage
of a $10,000 investment1,2
Class I $34 0.70%
1.
Reflects fee waivers and/or expense reimbursements, without which expenses would have been higher.
2.
Annualized.
Expenses Paid, Amount $ 34
Expense Ratio, Percent 0.70% [84],[85]
Performance Past Does Not Indicate Future [Text] Keep in mind that the Fund ’s past performance is not a good predictor of how the Fund will perform in the future.
Line Graph [Table Text Block]
Fund Performance
The following graph compares the initial and subsequent account values at the end of each of the most recently completed 10 semiannual reporting periods of the Fund (or for the life of the Fund, if shorter). It assumes a $10,000 initial investment at the beginning of the first fiscal period in an appropriate, broad-based securities market index and other additional indexes, if applicable, for the same period and reflects the deduction of all sales charges, where applicable. One of the Fund's subadvisors changed effective January 9, 2017, and the Fund's principal investment strategies changed effective February 28, 2017 and March 13, 2017. Effective April 26, 2021, the Fund replaced both of its subadvisors and modified its principal investment strategies. The past performance in the graph and table prior to that date reflects the Fund’s prior subadvisors and principal investment strategies.
Fund Performance - Growth of 10K
Average Annual Return [Table Text Block]
Average Annual Total Returns for the Period Ended April 30, 2025 Inception
Date		 Six
Months1		 One
Year		 Five
Years		 Ten
Years
Class I Shares 1/21/1971 (2.46)% 8.19% 14.52% 9.80%
Russell 3000®Index2 (2.15)% 11.40% 15.12% 11.68%
Russell 1000® Value Index3 (1.86)% 8.55% 13.00% 8.36%
Morningstar Large Value Category Average4 (2.27)% 7.57% 13.36% 8.45%
1.
Not annualized.
2.
The Fund has selected the Russell 3000® Index to represent a broad measure of market performance. The Russell 3000® Index measures the performance of the largest 3,000 U.S. companies representing approximately 98% of the investable U.S. equity market.
3.
The Russell 1000® Value Index, which is generally representative of the market sectors or types of investments in which the Fund invests, 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.
4.
The Morningstar Large Value Category Average is representative of funds that invest primarily in big U.S. companies that are less expensive or growing more slowly than other large-cap stocks. Results are based on average total returns of similar funds with all dividends and capital gain distributions reinvested.
Performance Inception Date Jan. 21, 1971
No Deduction of Taxes [Text Block] The graph and table do not reflect the deduction of taxes that a shareholder would pay on Fund distributions or redemption of Fund shares.
Updated Performance Information Location [Text Block] Visit newyorklifeinvestments.com/funds for the most recent performance information.
Net Assets $ 920,939,860
Holdings Count | Holding 68
Investment Company Portfolio Turnover 21.00%
Additional Fund Statistics [Text Block]
Key Fund Statistics
Fund's net assets $920,939,860%
Total number of portfolio holdings 68%
Portfolio turnover rate 21%
Holdings [Text Block]
Graphical Representation of Holdings
The tables below show the investment makeup of the Fund; percentages indicated are based on the Fund's net assets.
Top Ten Holdings and/or Issuers*
JPMorgan Chase & Co. 3.9%
Johnson & Johnson 3.2%
UnitedHealth Group, Inc. 2.7%
Cisco Systems, Inc. 2.4%
Gilead Sciences, Inc. 2.1%
American International Group, Inc. 2.1%
Pfizer, Inc. 1.9%
Johnson Controls International plc 1.9%
Elevance Health, Inc. 1.9%
Marsh & McLennan Cos., Inc. 1.8%
* Excluding short-term investments
Top Industries 
Pharmaceuticals 9.2%
Oil, Gas & Consumable Fuels 9.1%
Capital Markets 8.2%
Banks 7.9%
Insurance 6.8%
Health Care Providers & Services 6.3%
Communications Equipment 3.6%
Multi–Utilities 3.3%
Specialized REITs 3.1%
Machinery 2.8%
Largest Holdings [Text Block]
Top Ten Holdings and/or Issuers*
JPMorgan Chase & Co. 3.9%
Johnson & Johnson 3.2%
UnitedHealth Group, Inc. 2.7%
Cisco Systems, Inc. 2.4%
Gilead Sciences, Inc. 2.1%
American International Group, Inc. 2.1%
Pfizer, Inc. 1.9%
Johnson Controls International plc 1.9%
Elevance Health, Inc. 1.9%
Marsh & McLennan Cos., Inc. 1.8%
* Excluding short-term investments
C000185571 [Member]  
Shareholder Report [Line Items]  
Fund Name NYLI WMC Value Fund
Class Name Class R6
Trading Symbol MMPDX
Annual or Semi-Annual Statement [Text Block] This semiannual shareholder report contains important information about NYLI WMC Value Fund (the "Fund") for the period November 1, 2024 to April 30, 2025.
Shareholder Report Annual or Semi-Annual semi-annual shareholder report
Additional Information [Text Block] You can find additional information about the Fund at dfinview.com/NYLIM. You can also request this information by contacting us at 800-624-6782.
Additional Information Phone Number 800-624-6782
Additional Information Website dfinview.com/NYLIM
Expenses [Text Block]
What were the Fund costs for the last six months?
(Based on a hypothetical $10,000 investment)
Share Class Name Costs of a $10,000 investment Costs paid as a percentage
of a $10,000 investment1
Class R6 $34 0.70%
1.
Annualized.
Expenses Paid, Amount $ 34
Expense Ratio, Percent 0.70% [86]
Performance Past Does Not Indicate Future [Text] Keep in mind that the Fund ’s past performance is not a good predictor of how the Fund will perform in the future.
Line Graph [Table Text Block]
Fund Performance
The following graph compares the initial and subsequent account values at the end of each of the most recently completed 10 semiannual reporting periods of the Fund (or for the life of the Fund, if shorter). It assumes a $10,000 initial investment at the beginning of the first fiscal period in an appropriate, broad-based securities market index and other additional indexes, if applicable, for the same period and reflects the deduction of all sales charges, where applicable.
Fund Performance - Growth of 10K
Average Annual Return [Table Text Block]
Average Annual Total Returns for the Period Ended April 30, 2025 Inception
Date		 Six
Months1		 One
Year		 Since
Inception
Class R6 Shares 4/26/2021 (2.43)% 8.21% 5.97%
Russell 3000®Index2 (2.15)% 11.40% 7.46%
Russell 1000® Value Index3 (1.86)% 8.55% 6.08%
Morningstar Large Value Category Average4 (2.27)% 7.57% 6.57%
1.
Not annualized.
2.
The Fund has selected the Russell 3000® Index to represent a broad measure of market performance. The Russell 3000® Index measures the performance of the largest 3,000 U.S. companies representing approximately 98% of the investable U.S. equity market.
3.
The Russell 1000® Value Index, which is generally representative of the market sectors or types of investments in which the Fund invests, 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.
4.
The Morningstar Large Value Category Average is representative of funds that invest primarily in big U.S. companies that are less expensive or growing more slowly than other large-cap stocks. Results are based on average total returns of similar funds with all dividends and capital gain distributions reinvested.
Performance Inception Date Apr. 26, 2021
No Deduction of Taxes [Text Block] The graph and table do not reflect the deduction of taxes that a shareholder would pay on Fund distributions or redemption of Fund shares.
Updated Performance Information Location [Text Block] Visit newyorklifeinvestments.com/funds for the most recent performance information.
Net Assets $ 920,939,860
Holdings Count | Holding 68
Investment Company Portfolio Turnover 21.00%
Additional Fund Statistics [Text Block]
Key Fund Statistics
Fund's net assets $920,939,860%
Total number of portfolio holdings 68%
Portfolio turnover rate 21%
Holdings [Text Block]
Graphical Representation of Holdings
The tables below show the investment makeup of the Fund; percentages indicated are based on the Fund's net assets.
Top Ten Holdings and/or Issuers*
JPMorgan Chase & Co. 3.9%
Johnson & Johnson 3.2%
UnitedHealth Group, Inc. 2.7%
Cisco Systems, Inc. 2.4%
Gilead Sciences, Inc. 2.1%
American International Group, Inc. 2.1%
Pfizer, Inc. 1.9%
Johnson Controls International plc 1.9%
Elevance Health, Inc. 1.9%
Marsh & McLennan Cos., Inc. 1.8%
* Excluding short-term investments
Top Industries 
Pharmaceuticals 9.2%
Oil, Gas & Consumable Fuels 9.1%
Capital Markets 8.2%
Banks 7.9%
Insurance 6.8%
Health Care Providers & Services 6.3%
Communications Equipment 3.6%
Multi–Utilities 3.3%
Specialized REITs 3.1%
Machinery 2.8%
Largest Holdings [Text Block]
Top Ten Holdings and/or Issuers*
JPMorgan Chase & Co. 3.9%
Johnson & Johnson 3.2%
UnitedHealth Group, Inc. 2.7%
Cisco Systems, Inc. 2.4%
Gilead Sciences, Inc. 2.1%
American International Group, Inc. 2.1%
Pfizer, Inc. 1.9%
Johnson Controls International plc 1.9%
Elevance Health, Inc. 1.9%
Marsh & McLennan Cos., Inc. 1.8%
* Excluding short-term investments
C000060801 [Member]  
Shareholder Report [Line Items]  
Fund Name NYLI WMC Value Fund
Class Name Investor Class
Trading Symbol MSMIX
Annual or Semi-Annual Statement [Text Block] This semiannual shareholder report contains important information about NYLI WMC Value Fund (the "Fund") for the period November 1, 2024 to April 30, 2025.
Shareholder Report Annual or Semi-Annual semi-annual shareholder report
Additional Information [Text Block] You can find additional information about the Fund at dfinview.com/NYLIM. You can also request this information by contacting us at 800-624-6782.
Additional Information Phone Number 800-624-6782
Additional Information Website dfinview.com/NYLIM
Expenses [Text Block]
What were the Fund costs for the last six months?
(Based on a hypothetical $10,000 investment)
Share Class Name Costs of a $10,000 investment Costs paid as a percentage
of a $10,000 investment1
Investor Class $61 1.25%
1.
Annualized.
Expenses Paid, Amount $ 61
Expense Ratio, Percent 1.25% [87]
Performance Past Does Not Indicate Future [Text] Keep in mind that the Fund ’s past performance is not a good predictor of how the Fund will perform in the future.
Line Graph [Table Text Block]
Fund Performance
The following graph compares the initial and subsequent account values at the end of each of the most recently completed 10 semiannual reporting periods of the Fund (or for the life of the Fund, if shorter). It assumes a $10,000 initial investment at the beginning of the first fiscal period in an appropriate, broad-based securities market index and other additional indexes, if applicable, for the same period and reflects the deduction of all sales charges, where applicable. One of the Fund's subadvisors changed effective January 9, 2017, and the Fund's principal investment strategies changed effective February 28, 2017 and March 13, 2017. Effective April 26, 2021, the Fund replaced both of its subadvisors and modified its principal investment strategies. The past performance in the graph and table prior to that date reflects the Fund’s prior subadvisors and principal investment strategies.
Fund Performance - Growth of 10K
Average Annual Return [Table Text Block]
Average Annual Total Returns for the Period Ended April 30, 2025 Inception
Date		 Six
Months1		 One
Year		 Five
Years		 Ten
Years
Investor Class Shares - Including sales charges 2/28/2008 (7.55)% 2.23% 12.59% 8.62%
Investor Class Shares - Excluding sales charges (2.68)% 7.61% 13.87% 9.24%
Russell 3000®Index2 (2.15)% 11.40% 15.12% 11.68%
Russell 1000® Value Index3 (1.86)% 8.55% 13.00% 8.36%
Morningstar Large Value Category Average4 (2.27)% 7.57% 13.36% 8.45%
1.
Not annualized.
2.
The Fund has selected the Russell 3000® Index to represent a broad measure of market performance. The Russell 3000® Index measures the performance of the largest 3,000 U.S. companies representing approximately 98% of the investable U.S. equity market.
3.
The Russell 1000® Value Index, which is generally representative of the market sectors or types of investments in which the Fund invests, 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.
4.
The Morningstar Large Value Category Average is representative of funds that invest primarily in big U.S. companies that are less expensive or growing more slowly than other large-cap stocks. Results are based on average total returns of similar funds with all dividends and capital gain distributions reinvested.
Performance Inception Date Feb. 28, 2008
No Deduction of Taxes [Text Block] The graph and table do not reflect the deduction of taxes that a shareholder would pay on Fund distributions or redemption of Fund shares.
Updated Performance Information Location [Text Block] Visit newyorklifeinvestments.com/funds for the most recent performance information.
Net Assets $ 920,939,860
Holdings Count | Holding 68
Investment Company Portfolio Turnover 21.00%
Additional Fund Statistics [Text Block]
Key Fund Statistics
Fund's net assets $920,939,860%
Total number of portfolio holdings 68%
Portfolio turnover rate 21%
Holdings [Text Block]
Graphical Representation of Holdings
The tables below show the investment makeup of the Fund; percentages indicated are based on the Fund's net assets.
Top Ten Holdings and/or Issuers*
JPMorgan Chase & Co. 3.9%
Johnson & Johnson 3.2%
UnitedHealth Group, Inc. 2.7%
Cisco Systems, Inc. 2.4%
Gilead Sciences, Inc. 2.1%
American International Group, Inc. 2.1%
Pfizer, Inc. 1.9%
Johnson Controls International plc 1.9%
Elevance Health, Inc. 1.9%
Marsh & McLennan Cos., Inc. 1.8%
* Excluding short-term investments
Top Industries 
Pharmaceuticals 9.2%
Oil, Gas & Consumable Fuels 9.1%
Capital Markets 8.2%
Banks 7.9%
Insurance 6.8%
Health Care Providers & Services 6.3%
Communications Equipment 3.6%
Multi–Utilities 3.3%
Specialized REITs 3.1%
Machinery 2.8%
Largest Holdings [Text Block]
Top Ten Holdings and/or Issuers*
JPMorgan Chase & Co. 3.9%
Johnson & Johnson 3.2%
UnitedHealth Group, Inc. 2.7%
Cisco Systems, Inc. 2.4%
Gilead Sciences, Inc. 2.1%
American International Group, Inc. 2.1%
Pfizer, Inc. 1.9%
Johnson Controls International plc 1.9%
Elevance Health, Inc. 1.9%
Marsh & McLennan Cos., Inc. 1.8%
* Excluding short-term investments
[1] Annualized.
[2] Annualized.
[3] Reflects fee waivers and/or expense reimbursements, without which expenses would have been higher.
[4] Annualized.
[5] Reflects fee waivers and/or expense reimbursements, without which expenses would have been higher.
[6] Annualized.
[7] Annualized.
[8] Reflects fee waivers and/or expense reimbursements, without which expenses would have been higher.
[9] Annualized.
[10] Reflects fee waivers and/or expense reimbursements, without which expenses would have been higher.
[11] Annualized.
[12] Reflects fee waivers and/or expense reimbursements, without which expenses would have been higher.
[13] Annualized.
[14] Reflects fee waivers and/or expense reimbursements, without which expenses would have been higher.
[15] Annualized.
[16] Annualized.
[17] Reflects fee waivers and/or expense reimbursements, without which expenses would have been higher.
[18] Annualized.
[19] Annualized.
[20] Annualized.
[21] Annualized.
[22] Annualized.
[23] Annualized.
[24] Annualized.
[25] Annualized.
[26] Annualized.
[27] Annualized.
[28] Reflects fee waivers and/or expense reimbursements, without which expenses would have been higher.
[29] Annualized.
[30] Reflects fee waivers and/or expense reimbursements, without which expenses would have been higher.
[31] Annualized.
[32] Annualized.
[33] Annualized.
[34] Annualized.
[35] Annualized.
[36] Annualized.
[37] Annualized.
[38] Annualized.
[39] Annualized.
[40] Annualized.
[41] Reflects fee waivers and/or expense reimbursements, without which expenses would have been higher.
[42] Annualized.
[43] Annualized.
[44] Annualized.
[45] Reflects fee waivers and/or expense reimbursements, without which expenses would have been higher.
[46] Annualized.
[47] Annualized.
[48] Annualized.
[49] Reflects fee waivers and/or expense reimbursements, without which expenses would have been higher.
[50] Annualized.
[51] Annualized.
[52] Reflects fee waivers and/or expense reimbursements, without which expenses would have been higher.
[53] Annualized.
[54] Reflects fee waivers and/or expense reimbursements, without which expenses would have been higher.
[55] Annualized.
[56] Reflects fee waivers and/or expense reimbursements, without which expenses would have been higher.
[57] Annualized.
[58] Reflects fee waivers and/or expense reimbursements, without which expenses would have been higher.
[59] Annualized.
[60] Annualized.
[61] Annualized.
[62] Annualized.
[63] Annualized.
[64] Annualized.
[65] Reflects fee waivers and/or expense reimbursements, without which expenses would have been higher.
[66] Annualized.
[67] Reflects fee waivers and/or expense reimbursements, without which expenses would have been higher.
[68] Annualized.
[69] Reflects fee waivers and/or expense reimbursements, without which expenses would have been higher.
[70] Annualized.
[71] Reflects fee waivers and/or expense reimbursements, without which expenses would have been higher.
[72] Annualized.
[73] Reflects fee waivers and/or expense reimbursements, without which expenses would have been higher.
[74] Annualized.
[75] Reflects fee waivers and/or expense reimbursements, without which expenses would have been higher.
[76] Annualized.
[77] Reflects fee waivers and/or expense reimbursements, without which expenses would have been higher.
[78] Annualized.
[79] Reflects fee waivers and/or expense reimbursements, without which expenses would have been higher.
[80] Annualized.
[81] Reflects fee waivers and/or expense reimbursements, without which expenses would have been higher.
[82] Annualized.
[83] Annualized.
[84] Annualized.
[85] Reflects fee waivers and/or expense reimbursements, without which expenses would have been higher.
[86] Annualized.
[87] Annualized.