| Form N-CSR Cover | 12 Months Ended |
| Dec. 31, 2024 | |
| Shareholder Report [Line Items] | |
| Document Type | N-CSR |
| Amendment Flag | false |
| Registrant Name | BNY Mellon Investment Portfolios |
| Entity Central Index Key | 0001056707 |
| Entity Investment Company Type | N-1A |
| Document Period End Date | Dec. 31, 2024 |
| Shareholder Report | 12 Months Ended | |
| Dec. 31, 2024 USD ($) Holding | ||
| Shareholder Report [Line Items] | ||
| Document Type | N-CSR | |
| Amendment Flag | false | |
| Registrant Name | BNY Mellon Investment Portfolios | |
| Entity Central Index Key | 0001056707 | |
| Entity Investment Company Type | N-1A | |
| Document Period End Date | Dec. 31, 2024 | |
| C000007611 [Member] | ||
| Shareholder Report [Line Items] | ||
| Fund Name | Midcap Stock Portfolio | |
| Class Name | Initial Shares | |
| No Trading Symbol Flag | true | |
| Annual or Semi-Annual Statement [Text Block] | This annual shareholder report contains important information about BNY Mellon Investment Portfolios, MidCap Stock Portfolio (the “Fund”) for the period of January 1, 2024 to December 31, 2024. | |
| Shareholder Report Annual or Semi-Annual | annual shareholder report | |
| Additional Information [Text Block] | You can find additional information about the Fund at www.bny.com/investments/us/en/intermediary/products/variable-products.html#funds-table-tabs1 | |
| Additional Information Phone Number | 1-800-373-9387 | |
| Additional Information Email | info@bny.com | |
| Additional Information Website | www.bny.com/investments/us/en/intermediary/products/variable-products.html#funds-table-tabs1 | |
| Expenses [Text Block] | What were the Fund’s costs for the last year ? (based on a hypothetical $10,000 investment) Share Class Costs of a $10,000 investment Costs paid as a percentage of a $10,000 investment Initial Shares * $ 0.81 % * During the period, fees were waived and/or expenses reimbursed pursuant to an agreement with the Fund’s investment adviser, BNY Mellon Investment Adviser, Inc. If this agreement is not extended in the future, expenses could be higher. | |
| Expenses Paid, Amount | $ 86 | [1] |
| Expense Ratio, Percent | 0.81% | [1] |
| Factors Affecting Performance [Text Block] | How did the Fund perform last year ? For the 12-month period ended December 31, 2024, the Fund’s Initial Shares returned 12.61%. In comparison, the S&P MidCap 400 ® What affected the Fund’s performance? U.S. stocks rose as investors rewarded high-growth-oriented companies, including companies with exposure to artificial intelligence investment themes. Index performance was stronger in utilities and weaker in materials. Stock selection in the consumer staples, industrials and financials sectors contributed to the Fund’s performance relative to the Index. Stock selection in the information technology and real estate sectors detracted most from relative performance. Not FDIC Insured. Not Bank-Guaranteed. May Lose Value | |
| Performance Past Does Not Indicate Future [Text] | The Fund’s past performance is not a good predictor of the Fund’s future performance. | |
| Line Graph [Table Text Block] | How did the Fund perform over the past 10 years? The Fund’s past performance is not a good predictor of the Fund’s future performance. Cumulative Performance from January 1 , 2014 through December 31, 2024 Initial Investment of $10,000 The above graph compares a hypothetical $10,000 investment in the Fund’s Initial Shares to a hypothetical investment of $10,000 made in each of the S&P 1500 ® ® | |
| Average Annual Return [Table Text Block] | AVERAGE ANNUAL TOTAL RETURNS (AS OF 12/31/24 ) Share Class 1YR 5YR 10YR Initial Shares 12.61 % 9.27 % 7.49 % S&P 1500 ® * 23.95 % 14.13 % 12.79 % S&P MidCap 400 ® 13.93 % 10.34 % 9.68 % * In accordance with regulatory changes requiring the Fund’s primary benchmark to represent the overall applicable market, the Fund’s primary prospectus benchmark changed to the indicated benchmark effective as of December 31, 2024. | |
| 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. | |
| Performance Table Market Index Changed [Text Block] | In accordance with regulatory changes requiring the Fund’s primary benchmark to represent the overall applicable market, the Fund’s primary prospectus benchmark changed to the indicated benchmark effective as of December 31, 2024. | |
| Updated Performance Information Location [Text Block] | For more current information visitwww.bny.com/investments/us/en/intermediary/products/variable-products.html#funds-table-tabs1. | |
| Net Assets | $ 158,000,000 | |
| Holdings Count | Holding | 265 | |
| Advisory Fees Paid, Amount | $ 1,063,842 | |
| Investment Company Portfolio Turnover | 59.03% | |
| Additional Fund Statistics [Text Block] | KEY FUND STATISTICS (AS OF 12/31/24 ) Total Advisory Fee Paid During $ 265 $ 59.03 % Not FDIC Insured. Not Bank-Guaranteed. May Lose Value | |
| Holdings [Text Block] | Portfolio Holdings (as of 12/31/24 ) Top Ten Holdings (Based on Net Assets) * * Excludes money market funds or other short-term securities held for the investment of cash and cash collateral for securities loaned, if any. Sector Allocation (Based on Net Assets) | |
| Largest Holdings [Text Block] | Top Ten Holdings (Based on Net Assets) * * Excludes money market funds or other short-term securities held for the investment of cash and cash collateral for securities loaned, if any. | |
| C000007612 [Member] | ||
| Shareholder Report [Line Items] | ||
| Fund Name | Midcap Stock Portfolio | |
| Class Name | Service Shares | |
| No Trading Symbol Flag | true | |
| Annual or Semi-Annual Statement [Text Block] | This annual shareholder report contains important information about BNY Mellon Investment Portfolios, MidCap Stock Portfolio (the “Fund”) for the period of January 1, 2024 to December 31, 2024. | |
| Shareholder Report Annual or Semi-Annual | annual shareholder report | |
| Additional Information [Text Block] | You can find additional information about the Fund at www.bny.com/investments/us/en/intermediary/products/variable-products.html#funds-table-tabs1 | |
| Additional Information Phone Number | 1-800-373-9387 | |
| Additional Information Email | info@bny.com | |
| Additional Information Website | www.bny.com/investments/us/en/intermediary/products/variable-products.html#funds-table-tabs1 | |
| Expenses [Text Block] | What were the Fund’s costs for the last year ? (based on a hypothetical $10,000 investment) Share Class Costs of a $10,000 investment Costs paid as a percentage of a $10,000 investment Service Shares * $ 1.06 % * During the period, fees were waived and/or expenses reimbursed pursuant to an agreement with the Fund’s investment adviser, BNY Mellon Investment Adviser, Inc. If this agreement is not extended in the future, expenses could be higher. | |
| Expenses Paid, Amount | $ 113 | [2] |
| Expense Ratio, Percent | 1.06% | [2] |
| Factors Affecting Performance [Text Block] | How did the Fund perform last year ? For the 12-month period ended December 31, 2024, the Fund’s Service Shares returned 12.33%. In comparison, the S&P MidCap 400 ® What affected the Fund’s performance? U.S. stocks rose as investors rewarded high-growth-oriented companies, including companies with exposure to artificial intelligence investment themes. Index performance was stronger in utilities and weaker in materials. Stock selection in the consumer staples, industrials and financials sectors contributed to the Fund’s performance relative to the Index. Stock selection in the information technology and real estate sectors detracted most from relative performance. Not FDIC Insured. Not Bank-Guaranteed. May Lose Value | |
| Performance Past Does Not Indicate Future [Text] | The Fund’s past performance is not a good predictor of the Fund’s future performance. | |
| Line Graph [Table Text Block] | How did the Fund perform over the past 10 years? The Fund’s past performance is not a good predictor of the Fund’s future performance. Cumulative Performance from January 1 , 2014 through December 31, 2024 Initial Investment of $10,000 The above graph compares a hypothetical $10,000 investment in the Fund’s Service Shares to a hypothetical investment of $10,000 made in each of the S&P 1500 ® ® | |
| Average Annual Return [Table Text Block] | AVERAGE ANNUAL TOTAL RETURNS (AS OF 12/31/24 ) Share Class 1YR 5YR 10YR Service Shares 12.33 % 9.00 % 7.22 % S&P 1500 ® * 23.95 % 14.13 % 12.79 % S&P MidCap 400 ® 13.93 % 10.34 % 9.68 % * In accordance with regulatory changes requiring the Fund’s primary benchmark to represent the overall applicable market, the Fund’s primary prospectus benchmark changed to the indicated benchmark effective as of December 31, 2024. | |
| 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. | |
| Performance Table Market Index Changed [Text Block] | In accordance with regulatory changes requiring the Fund’s primary benchmark to represent the overall applicable market, the Fund’s primary prospectus benchmark changed to the indicated benchmark effective as of December 31, 2024. | |
| Updated Performance Information Location [Text Block] | For more current information visitwww.bny.com/investments/us/en/intermediary/products/variable-products.html#funds-table-tabs1. | |
| Net Assets | $ 158,000,000 | |
| Holdings Count | Holding | 265 | |
| Advisory Fees Paid, Amount | $ 1,063,842 | |
| Investment Company Portfolio Turnover | 59.03% | |
| Additional Fund Statistics [Text Block] | KEY FUND STATISTICS (AS OF 12/31/24 ) Total Advisory Fee Paid During $ 265 $ 59.03 % Not FDIC Insured. Not Bank-Guaranteed. May Lose Value | |
| Holdings [Text Block] | Portfolio Holdings (as of 12/31/24 ) Top Ten Holdings (Based on Net Assets) * * Excludes money market funds or other short-term securities held for the investment of cash and cash collateral for securities loaned, if any. Sector Allocation (Based on Net Assets) | |
| Largest Holdings [Text Block] | Top Ten Holdings (Based on Net Assets) * * Excludes money market funds or other short-term securities held for the investment of cash and cash collateral for securities loaned, if any. | |
| C000007613 [Member] | ||
| Shareholder Report [Line Items] | ||
| Fund Name | Small Cap Stock Index Portfolio | |
| Class Name | Service Shares | |
| No Trading Symbol Flag | true | |
| Annual or Semi-Annual Statement [Text Block] | This annual shareholder report contains important information about BNY Mellon Investment Portfolios, Small Cap Stock Index Portfolio (the “Fund”) for the period of January 1, 2024 to December 31, 2024. | |
| Shareholder Report Annual or Semi-Annual | annual shareholder report | |
| Additional Information [Text Block] | You can find additional information about the Fund at www.bny.com/investments/us/en/intermediary/products/variable-products.html#funds-table-tabs1 | |
| Additional Information Phone Number | 1-800-373-9387 | |
| Additional Information Email | info@bny.com | |
| Additional Information Website | www.bny.com/investments/us/en/intermediary/products/variable-products.html#funds-table-tabs1 | |
| Expenses [Text Block] | What were the Fund’s costs for the last year ? (based on a hypothetical $10,000 investment) Share Class Costs of a $10,000 investment Costs paid as a percentage of a $10,000 investment Service Shares * $ 0.61 % * During the period, fees were waived and/or expenses reimbursed pursuant to an agreement with the Fund’s investment adviser, BNY Mellon Investment Adviser, Inc. | |
| Expenses Paid, Amount | $ 63 | [3] |
| Expense Ratio, Percent | 0.61% | [3] |
| Factors Affecting Performance [Text Block] | How did the Fund perform last year ? For the 12-month period ended December 31, 2024, the Fund’s Service Shares returned 7.96%. In comparison, the S&P SmallCap 600 ® What affected the Fund’s performance? Small-cap equities posted positive returns amid resilient economic growth, moderating inflation, and rising corporate profits, but trailed larger-cap markets. Growth-oriented stocks outperformed value-oriented shares due to the improving economic outlook, rising corporate profits, and the prospect of lower interest rates. The best-performing small-cap sector was financials, which stood to benefit from the reduction in regulatory oversight promised by the incoming presidential administration, followed by industrials and communication services. Only two sectors posted negative returns, with energy stocks hurt by volatile prices and information technology small caps lacking the resources to compete in the development of artificial intelligence. The difference in returns between the Fund and the Index resulted primarily from transaction costs and operating expenses that are not reflected in index results. Not FDIC Insured. Not Bank-Guaranteed. May Lose Value | |
| Performance Past Does Not Indicate Future [Text] | The Fund’s past performance is not a good predictor of the Fund’s future performance. | |
| Line Graph [Table Text Block] | How did the Fund perform over the past 10 years? The Fund’s past performance is not a good predictor of the Fund’s future performance. Cumulative Performance from January 1 , 2014 through December 31, 2024 Initial Investment of $10,000 The above graph compares a hypothetical $10,000 investment in the Fund’s Service Shares to a hypothetical investment of $10,000 made in each of the S&P 1500 ® ® | |
| Average Annual Return [Table Text Block] | AVERAGE ANNUAL TOTAL RETURNS (AS OF 12/31/24 ) Share Class 1YR 5YR 10YR Small Cap Stock Index Portfolio 7.96 % 7.70 % 8.33 % S&P 1500 ® * 23.95 % 14.13 % 12.79 % S&P SmallCap 600 ® 8.70 % 8.36 % 8.96 % * In accordance with regulatory changes requiring the Fund to compare its performance with a broad-based securities market index that represents the overall applicable market, the Fund added the indicated benchmark effective December 31, 2024. | |
| 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. | |
| Performance Table Market Index Changed [Text Block] | In accordance with regulatory changes requiring the Fund to compare its performance with a broad-based securities market index that represents the overall applicable market, the Fund added the indicated benchmark effective December 31, 2024. | |
| Updated Performance Information Location [Text Block] | For more current information visit www.bny.com/investments/us/en/intermediary/products/variable-products.html#funds-table-tabs1 | |
| Net Assets | $ 582,000,000 | |
| Holdings Count | Holding | 609 | |
| Advisory Fees Paid, Amount | $ 1,994,261 | |
| Investment Company Portfolio Turnover | 77.24% | |
| Additional Fund Statistics [Text Block] | KEY FUND STATISTICS (AS OF 12/31/24 ) Total Advisory Fee Paid During $ 609 $ 77.24 % Not FDIC Insured. Not Bank-Guaranteed. May Lose Value | |
| Holdings [Text Block] | Portfolio Holdings (as of 12/31/24 ) Top Ten Holdings (Based on Net Assets) * * Excludes money market funds or other short-term securities held for the investment of cash and cash collateral for securities loaned, if any. Sector Allocation (Based on Net Assets) | |
| Largest Holdings [Text Block] | Top Ten Holdings (Based on Net Assets) * * Excludes money market funds or other short-term securities held for the investment of cash and cash collateral for securities loaned, if any. | |
| C000007614 [Member] | ||
| Shareholder Report [Line Items] | ||
| Fund Name | Technology Growth Portfolio | |
| Class Name | Initial Shares | |
| No Trading Symbol Flag | true | |
| Annual or Semi-Annual Statement [Text Block] | This annual shareholder report contains important information about BNY Mellon Investment Portfolios, Technology Growth Portfolio (the “Fund”) for the period of January 1, 2024 to December 31, 2024. | |
| Shareholder Report Annual or Semi-Annual | annual shareholder report | |
| Additional Information [Text Block] | You can find additional information about the Fund at www.bny.com/investments/us/en/intermediary/products/variable-products.html#funds-table-tabs1 | |
| Additional Information Phone Number | 1-800-373-9387 | |
| Additional Information Email | info@bny.com | |
| Additional Information Website | www.bny.com/investments/us/en/intermediary/products/variable-products.html#funds-table-tabs1 | |
| Expenses [Text Block] | What were the Fund’s costs for the last year ? (based on a hypothetical $10,000 investment) Share Class Costs of a $10,000 investment Costs paid as a percentage of a $10,000 investment Initial Shares $ 0.77 % | |
| Expenses Paid, Amount | $ 87 | |
| Expense Ratio, Percent | 0.77% | |
| Factors Affecting Performance [Text Block] | How did the Fund perform last year ? For the 12-month period ended December 31, 2024, the Fund’s Initial Shares returned 25.74%. In comparison, the NYSE ® What affected the Fund’s performance? Strong market returns in 2024 were driven by the AI theme, especially by key enablers like the Magnificent 7, which remain at the forefront of investing in the new technology. The Fund benefited from stock selection, especially in the semiconductor industry and the consumer discretionary sector. Overweights in communication services and industrials also contributed. Fund performance was hindered by two real estate-related positions, which were hurt by higher interest rates. Rates rose on the prospect that growth-oriented policies from President Trump could reignite inflation. Underweights in an EV company and an auto components firm also detracted, as did positions in IT services. Not FDIC Insured. Not Bank-Guaranteed. May Lose Value | |
| Performance Past Does Not Indicate Future [Text] | The Fund’s past performance is not a good predictor of the Fund’s future performance. | |
| Line Graph [Table Text Block] | How did the Fund perform over the past 10 years? The Fund’s past performance is not a good predictor of the Fund’s future performance. Cumulative Performance from January 1 , 2014 through December 31, 2024 Initial Investment of $10,000 The above graph compares a hypothetical $10,000 investment in the Fund’s Initial Shares to a hypothetical investment of $10,000 made in each of the S&P 500 ® ® | |
| Average Annual Return [Table Text Block] | AVERAGE ANNUAL TOTAL RETURNS (AS OF 12/31/24 ) Share Class 1YR 5YR 10YR Initial Shares 25.74 % 15.58 % 15.08 % S&P 500 ® * 25.02 % 14.52 % 13.10 % NYSE ® 23.84 % 20.83 % 19.15 % * In accordance with regulatory changes requiring the Fund’s primary benchmark to represent the overall applicable market, the Fund’s primary prospectus benchmark changed to the indicated benchmark effective as of December 31, 2024. | |
| 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. | |
| Performance Table Market Index Changed [Text Block] | In accordance with regulatory changes requiring the Fund’s primary benchmark to represent the overall applicable market, the Fund’s primary prospectus benchmark changed to the indicated benchmark effective as of December 31, 2024. | |
| Updated Performance Information Location [Text Block] | For more current information visit www.bny.com/investments/us/en/intermediary/products/variable-products.html#funds-table-tabs1 | |
| Net Assets | $ 1,234,000,000 | |
| Holdings Count | Holding | 43 | |
| Advisory Fees Paid, Amount | $ 8,650,478 | |
| Investment Company Portfolio Turnover | 34.96% | |
| Additional Fund Statistics [Text Block] | KEY FUND STATISTICS (AS OF 12/31/24 ) Total Advisory Fee Paid During $ 43 $ 34.96 % Not FDIC Insured. Not Bank-Guaranteed. May Lose Value | |
| Holdings [Text Block] | Portfolio Holdings (as of 12/31/24 ) Top Ten Holdings (Based on Net Assets) * * Excludes money market funds or other short-term securities held for the investment of cash and cash collateral for securities loaned, if any. Sector Allocation (Based on Net Assets) | |
| Largest Holdings [Text Block] | Top Ten Holdings (Based on Net Assets) * * Excludes money market funds or other short-term securities held for the investment of cash and cash collateral for securities loaned, if any. | |
| C000007615 [Member] | ||
| Shareholder Report [Line Items] | ||
| Fund Name | Technology Growth Portfolio | |
| Class Name | Service Shares | |
| No Trading Symbol Flag | true | |
| Annual or Semi-Annual Statement [Text Block] | This annual shareholder report contains important information about BNY Mellon Investment Portfolios, Technology Growth Portfolio (the “Fund”) for the period of January 1, 2024 to December 31, 2024. | |
| Shareholder Report Annual or Semi-Annual | annual shareholder report | |
| Additional Information [Text Block] | You can find additional information about the Fund at www.bny.com/investments/us/en/intermediary/products/variable-products.html#funds-table-tabs1 | |
| Additional Information Phone Number | 1-800-373-9387 | |
| Additional Information Email | info@bny.com | |
| Additional Information Website | www.bny.com/investments/us/en/intermediary/products/variable-products.html#funds-table-tabs1 | |
| Expenses [Text Block] | What were the Fund’s costs for the last year ? (based on a hypothetical $10,000 investment) Share Class Costs of a $10,000 investment Costs paid as a percentage of a $10,000 investment Service Shares $ 1.02 % | |
| Expenses Paid, Amount | $ 115 | |
| Expense Ratio, Percent | 1.02% | |
| Factors Affecting Performance [Text Block] | How did the Fund perform last year ? For the 12-month period ended December 31, 2024, the Fund’s Service Shares returned 25.39%. In comparison, the NYSE ® What affected the Fund’s performance? Strong market returns in 2024 were driven by the AI theme, especially by key enablers like the Magnificent 7, which remain at the forefront of investing in the new technology. The Fund benefited from stock selection, especially in the semiconductor industry and the consumer discretionary sector. Overweights in communication services and industrials also contributed. Fund performance was hindered by two real estate-related positions, which were hurt by higher interest rates. Rates rose on the prospect that growth-oriented policies from President Trump could reignite inflation. Underweights in an EV company and an auto components firm also detracted, as did positions in IT services. Not FDIC Insured. Not Bank-Guaranteed. May Lose Value | |
| Performance Past Does Not Indicate Future [Text] | The Fund’s past performance is not a good predictor of the Fund’s future performance. | |
| Line Graph [Table Text Block] | How did the Fund perform over the past 10 years? The Fund’s past performance is not a good predictor of the Fund’s future performance. Cumulative Performance from January 1 , 2014 through December 31, 2024 Initial Investment of $10,000 The above graph compares a hypothetical $10,000 investment in the Fund’s Service Shares to a hypothetical investment of $10,000 made in each of the S&P 500 ® ® | |
| Average Annual Return [Table Text Block] | AVERAGE ANNUAL TOTAL RETURNS (AS OF 12/31/24 ) Share Class 1YR 5YR 10YR Service Shares 25.39 % 15.29 % 14.79 % S&P 500 ® * 25.02 % 14.52 % 13.10 % NYSE ® 23.84 % 20.83 % 19.15 % * In accordance with regulatory changes requiring the Fund’s primary benchmark to represent the overall applicable market, the Fund’s primary prospectus benchmark changed to the indicated benchmark effective as of December 31, 2024. | |
| 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. | |
| Performance Table Market Index Changed [Text Block] | In accordance with regulatory changes requiring the Fund’s primary benchmark to represent the overall applicable market, the Fund’s primary prospectus benchmark changed to the indicated benchmark effective as of December 31, 2024. | |
| Updated Performance Information Location [Text Block] | For more current information visit www.bny.com/investments/us/en/intermediary/products/variable-products.html#funds-table-tabs1 | |
| Net Assets | $ 1,234,000,000 | |
| Holdings Count | Holding | 43 | |
| Advisory Fees Paid, Amount | $ 8,650,478 | |
| Investment Company Portfolio Turnover | 34.96% | |
| Additional Fund Statistics [Text Block] | KEY FUND STATISTICS (AS OF 12/31/24 ) Total Advisory Fee Paid During $ 43 $ 34.96 % Not FDIC Insured. Not Bank-Guaranteed. May Lose Value | |
| Holdings [Text Block] | Portfolio Holdings (as of 12/31/24 ) Top Ten Holdings (Based on Net Assets) * * Excludes money market funds or other short-term securities held for the investment of cash and cash collateral for securities loaned, if any. Sector Allocation (Based on Net Assets) | |
| Largest Holdings [Text Block] | Top Ten Holdings (Based on Net Assets) * * Excludes money market funds or other short-term securities held for the investment of cash and cash collateral for securities loaned, if any. | |
| [1]During the period, fees were waived and/or expenses reimbursed pursuant to an agreement with the Fund’s investment adviser, BNY Mellon Investment Adviser, Inc. If this agreement is not extended in the future, expenses could be higher.[2]During the period, fees were waived and/or expenses reimbursed pursuant to an agreement with the Fund’s investment adviser, BNY Mellon Investment Adviser, Inc. If this agreement is not extended in the future, expenses could be higher.[3]During the period, fees were waived and/or expenses reimbursed pursuant to an agreement with the Fund’s investment adviser, BNY Mellon Investment Adviser, Inc. | ||
| Shareholder Report, Line Graph (Details) - USD ($) | 12 Months Ended | 60 Months Ended | 120 Months Ended | |||||||||||
| Dec. 31, 2024 | Dec. 31, 2024 | Dec. 31, 2024 | Dec. 31, 2023 | Dec. 31, 2022 | Dec. 31, 2021 | Dec. 31, 2020 | Dec. 31, 2019 | Dec. 31, 2018 | Dec. 31, 2017 | Dec. 31, 2016 | Dec. 31, 2015 | Dec. 31, 2014 | ||
| C000007611 [Member] | ||||||||||||||
| Account Value [Line Items] | ||||||||||||||
| Line Graph and Table Measure Name | Initial Shares | |||||||||||||
| Account Value | $ 20,599 | $ 20,599 | $ 20,599 | $ 18,291 | $ 15,460 | $ 17,993 | $ 14,294 | $ 13,222 | $ 11,001 | $ 13,018 | $ 11,283 | $ 9,771 | $ 10,000 | |
| Average Annual Return, Percent | 12.61% | 9.27% | 7.49% | |||||||||||
| C000007612 [Member] | ||||||||||||||
| Account Value [Line Items] | ||||||||||||||
| Line Graph and Table Measure Name | Service Shares | |||||||||||||
| Account Value | $ 20,084 | $ 20,084 | $ 20,084 | 17,879 | 15,154 | 17,679 | 14,080 | 13,056 | 10,893 | 12,919 | 11,230 | 9,748 | 10,000 | |
| Average Annual Return, Percent | 12.33% | 9% | 7.22% | |||||||||||
| C000007613 [Member] | ||||||||||||||
| Account Value [Line Items] | ||||||||||||||
| Line Graph and Table Measure Name | Small Cap Stock Index Portfolio | |||||||||||||
| Account Value | $ 22,250 | $ 22,250 | $ 22,250 | 20,610 | 17,861 | 21,429 | 16,988 | 15,355 | 12,564 | 13,803 | 12,280 | 9,767 | 10,000 | |
| Average Annual Return, Percent | 7.96% | 7.70% | 8.33% | |||||||||||
| C000007614 [Member] | ||||||||||||||
| Account Value [Line Items] | ||||||||||||||
| Line Graph and Table Measure Name | Initial Shares | |||||||||||||
| Account Value | $ 40,740 | $ 40,740 | $ 40,740 | 32,400 | 20,324 | 37,908 | 33,568 | 19,755 | 15,701 | 15,857 | 11,117 | 10,616 | 10,000 | |
| Average Annual Return, Percent | 25.74% | 15.58% | 15.08% | |||||||||||
| C000007615 [Member] | ||||||||||||||
| Account Value [Line Items] | ||||||||||||||
| Line Graph and Table Measure Name | Service Shares | |||||||||||||
| Account Value | $ 39,722 | $ 39,722 | $ 39,722 | 31,679 | 19,924 | 37,254 | 33,072 | 19,504 | 15,539 | 15,739 | 11,056 | 10,592 | 10,000 | |
| Average Annual Return, Percent | 25.39% | 15.29% | 14.79% | |||||||||||
| Standard & Poor's 500 Index [Member] | ||||||||||||||
| Account Value [Line Items] | ||||||||||||||
| Line Graph and Table Measure Name | S&P 500® Index (broad-based index) | |||||||||||||
| Account Value | [1] | $ 34,237 | $ 34,237 | $ 34,237 | 27,388 | 21,690 | 26,483 | 20,578 | 17,380 | 13,221 | 13,826 | 11,350 | 10,139 | 10,000 |
| Average Annual Return, Percent | [1] | 25.02% | 14.52% | 13.10% | ||||||||||
| NYSE Technology Index [Member] | ||||||||||||||
| Account Value [Line Items] | ||||||||||||||
| Line Graph and Table Measure Name | NYSE® Technology Index | |||||||||||||
| Account Value | $ 57,763 | $ 57,763 | $ 57,763 | 46,593 | 27,281 | 46,091 | 39,050 | 22,390 | 16,146 | 17,302 | 12,290 | 10,817 | 10,000 | |
| Average Annual Return, Percent | 23.84% | 20.83% | 19.15% | |||||||||||
| S And P 1500 Index [Member] | ||||||||||||||
| Account Value [Line Items] | ||||||||||||||
| Line Graph and Table Measure Name | S&P 1500® Index (broad-based index) | |||||||||||||
| Account Value | [2] | $ 33,322 | $ 33,322 | $ 33,322 | 26,884 | 21,427 | 26,060 | 20,288 | 17,205 | 13,144 | 13,830 | 11,417 | 10,101 | 10,000 |
| Average Annual Return, Percent | [2],[3] | 23.95% | 14.13% | 12.79% | ||||||||||
| S And P MidCap 400 Index [Member] | ||||||||||||||
| Account Value [Line Items] | ||||||||||||||
| Line Graph and Table Measure Name | S&P MidCap 400® Index | |||||||||||||
| Account Value | $ 25,196 | $ 25,196 | $ 25,196 | 22,116 | 18,993 | 21,846 | 17,511 | 15,406 | 12,208 | 13,729 | 11,811 | 9,782 | 10,000 | |
| Average Annual Return, Percent | 13.93% | 10.34% | 9.68% | |||||||||||
| S And P SmallCap 600 Index [Member] | ||||||||||||||
| Account Value [Line Items] | ||||||||||||||
| Line Graph and Table Measure Name | S&P SmallCap 600® Index | |||||||||||||
| Account Value | $ 23,579 | $ 23,579 | $ 23,579 | $ 21,693 | $ 18,692 | $ 22,279 | $ 17,568 | $ 15,786 | $ 12,857 | $ 14,048 | $ 12,407 | $ 9,803 | $ 10,000 | |
| Average Annual Return, Percent | 8.70% | 8.36% | 8.96% | |||||||||||
| [1]In accordance with regulatory changes requiring the Fund’s primary benchmark to represent the overall applicable market, the Fund’s primary prospectus benchmark changed to the indicated benchmark effective as of December 31, 2024.[2]In accordance with regulatory changes requiring the Fund’s primary benchmark to represent the overall applicable market, the Fund’s primary prospectus benchmark changed to the indicated benchmark effective as of December 31, 2024.[3]In accordance with regulatory changes requiring the Fund to compare its performance with a broad-based securities market index that represents the overall applicable market, the Fund added the indicated benchmark effective December 31, 2024. | ||||||||||||||
| Shareholder Report, Holdings (Details) | Dec. 31, 2024 | |
| C000007611 [Member] | RenaissanceRe Holdings Ltd [Member] | ||
| Holdings [Line Items] | ||
| Percent of Net Asset Value | 1.50% | [1] |
| C000007611 [Member] | Vistra Corp [Member] | ||
| Holdings [Line Items] | ||
| Percent of Net Asset Value | 1.40% | [1] |
| C000007611 [Member] | First Horizon Corp [Member] | ||
| Holdings [Line Items] | ||
| Percent of Net Asset Value | 1.30% | [1] |
| C000007611 [Member] | US Foods Holding Corp [Member] | ||
| Holdings [Line Items] | ||
| Percent of Net Asset Value | 1.20% | [1] |
| C000007611 [Member] | ITT Inc [Member] | ||
| Holdings [Line Items] | ||
| Percent of Net Asset Value | 1.20% | [1] |
| C000007611 [Member] | Eagle Materials Inc [Member] | ||
| Holdings [Line Items] | ||
| Percent of Net Asset Value | 1.30% | [1] |
| C000007611 [Member] | EMCOR Group Inc [Member] | ||
| Holdings [Line Items] | ||
| Percent of Net Asset Value | 2.20% | [1] |
| C000007611 [Member] | Williams Sonoma Inc [Member] | ||
| Holdings [Line Items] | ||
| Percent of Net Asset Value | 1.10% | [1] |
| C000007611 [Member] | Sprouts Farmers Markets Inc [Member] | ||
| Holdings [Line Items] | ||
| Percent of Net Asset Value | 1.10% | [1] |
| C000007611 [Member] | SEI Investments Co [Member] | ||
| Holdings [Line Items] | ||
| Percent of Net Asset Value | 0.90% | [1] |
| C000007611 [Member] | Energy Sector [Member] | ||
| Holdings [Line Items] | ||
| Percent of Net Asset Value | 4.80% | |
| C000007611 [Member] | Financial Services Sector [Member] | ||
| Holdings [Line Items] | ||
| Percent of Net Asset Value | 16.50% | |
| C000007611 [Member] | Healthcare Sector [Member] | ||
| Holdings [Line Items] | ||
| Percent of Net Asset Value | 9.90% | |
| C000007611 [Member] | Real Estate Sector [Member] | ||
| Holdings [Line Items] | ||
| Percent of Net Asset Value | 7.70% | |
| C000007611 [Member] | Communications Sector [Member] | ||
| Holdings [Line Items] | ||
| Percent of Net Asset Value | 1.90% | |
| C000007611 [Member] | Consumer Discretionary Sector [Member] | ||
| Holdings [Line Items] | ||
| Percent of Net Asset Value | 13.30% | |
| C000007611 [Member] | Consumer Staples Sector [Member] | ||
| Holdings [Line Items] | ||
| Percent of Net Asset Value | 5.90% | |
| C000007611 [Member] | Industrial Sector [Member] | ||
| Holdings [Line Items] | ||
| Percent of Net Asset Value | 19.80% | |
| C000007611 [Member] | Information Technology Sector [Member] | ||
| Holdings [Line Items] | ||
| Percent of Net Asset Value | 8.90% | |
| C000007611 [Member] | Materials Sector [Member] | ||
| Holdings [Line Items] | ||
| Percent of Net Asset Value | 6.20% | |
| C000007611 [Member] | Utilities Sector [Member] | ||
| Holdings [Line Items] | ||
| Percent of Net Asset Value | 4.60% | |
| C000007611 [Member] | Net Other Assets and Liabilities [Member] | ||
| Holdings [Line Items] | ||
| Percent of Net Asset Value | 0.50% | |
| C000007612 [Member] | RenaissanceRe Holdings Ltd [Member] | ||
| Holdings [Line Items] | ||
| Percent of Net Asset Value | 1.50% | [2] |
| C000007612 [Member] | Vistra Corp [Member] | ||
| Holdings [Line Items] | ||
| Percent of Net Asset Value | 1.40% | [2] |
| C000007612 [Member] | First Horizon Corp [Member] | ||
| Holdings [Line Items] | ||
| Percent of Net Asset Value | 1.30% | [2] |
| C000007612 [Member] | US Foods Holding Corp [Member] | ||
| Holdings [Line Items] | ||
| Percent of Net Asset Value | 1.20% | [2] |
| C000007612 [Member] | ITT Inc [Member] | ||
| Holdings [Line Items] | ||
| Percent of Net Asset Value | 1.20% | [2] |
| C000007612 [Member] | Eagle Materials Inc [Member] | ||
| Holdings [Line Items] | ||
| Percent of Net Asset Value | 1.30% | [2] |
| C000007612 [Member] | EMCOR Group Inc [Member] | ||
| Holdings [Line Items] | ||
| Percent of Net Asset Value | 2.20% | [2] |
| C000007612 [Member] | Williams Sonoma Inc [Member] | ||
| Holdings [Line Items] | ||
| Percent of Net Asset Value | 1.10% | [2] |
| C000007612 [Member] | Sprouts Farmers Markets Inc [Member] | ||
| Holdings [Line Items] | ||
| Percent of Net Asset Value | 1.10% | [2] |
| C000007612 [Member] | SEI Investments Co [Member] | ||
| Holdings [Line Items] | ||
| Percent of Net Asset Value | 0.90% | [2] |
| C000007612 [Member] | Energy Sector [Member] | ||
| Holdings [Line Items] | ||
| Percent of Net Asset Value | 4.80% | |
| C000007612 [Member] | Financial Services Sector [Member] | ||
| Holdings [Line Items] | ||
| Percent of Net Asset Value | 16.50% | |
| C000007612 [Member] | Healthcare Sector [Member] | ||
| Holdings [Line Items] | ||
| Percent of Net Asset Value | 9.90% | |
| C000007612 [Member] | Real Estate Sector [Member] | ||
| Holdings [Line Items] | ||
| Percent of Net Asset Value | 7.70% | |
| C000007612 [Member] | Communications Sector [Member] | ||
| Holdings [Line Items] | ||
| Percent of Net Asset Value | 1.90% | |
| C000007612 [Member] | Consumer Discretionary Sector [Member] | ||
| Holdings [Line Items] | ||
| Percent of Net Asset Value | 13.30% | |
| C000007612 [Member] | Consumer Staples Sector [Member] | ||
| Holdings [Line Items] | ||
| Percent of Net Asset Value | 5.90% | |
| C000007612 [Member] | Industrial Sector [Member] | ||
| Holdings [Line Items] | ||
| Percent of Net Asset Value | 19.80% | |
| C000007612 [Member] | Information Technology Sector [Member] | ||
| Holdings [Line Items] | ||
| Percent of Net Asset Value | 8.90% | |
| C000007612 [Member] | Materials Sector [Member] | ||
| Holdings [Line Items] | ||
| Percent of Net Asset Value | 6.20% | |
| C000007612 [Member] | Utilities Sector [Member] | ||
| Holdings [Line Items] | ||
| Percent of Net Asset Value | 4.60% | |
| C000007612 [Member] | Net Other Assets and Liabilities [Member] | ||
| Holdings [Line Items] | ||
| Percent of Net Asset Value | 0.50% | |
| C000007613 [Member] | iShares Core S And P Small Cap ETF [Member] | ||
| Holdings [Line Items] | ||
| Percent of Net Asset Value | 0.70% | [3] |
| C000007613 [Member] | Bath And Body Works Inc [Member] | ||
| Holdings [Line Items] | ||
| Percent of Net Asset Value | 0.60% | [3] |
| C000007613 [Member] | Glaukos Corp [Member] | ||
| Holdings [Line Items] | ||
| Percent of Net Asset Value | 0.60% | [3] |
| C000007613 [Member] | Alaska Air Group Inc [Member] | ||
| Holdings [Line Items] | ||
| Percent of Net Asset Value | 0.60% | [3] |
| C000007613 [Member] | ATI Inc [Member] | ||
| Holdings [Line Items] | ||
| Percent of Net Asset Value | 0.60% | [3] |
| C000007613 [Member] | Robert Half Inc [Member] | ||
| Holdings [Line Items] | ||
| Percent of Net Asset Value | 0.50% | [3] |
| C000007613 [Member] | VF Corp [Member] | ||
| Holdings [Line Items] | ||
| Percent of Net Asset Value | 0.50% | [3] |
| C000007613 [Member] | SPS Commerce Inc [Member] | ||
| Holdings [Line Items] | ||
| Percent of Net Asset Value | 0.50% | [3] |
| C000007613 [Member] | SPX Technologies Inc [Member] | ||
| Holdings [Line Items] | ||
| Percent of Net Asset Value | 0.50% | [3] |
| C000007613 [Member] | Jackson Financial Inc Cl A [Member] | ||
| Holdings [Line Items] | ||
| Percent of Net Asset Value | 0.50% | [3] |
| C000007613 [Member] | Energy Sector [Member] | ||
| Holdings [Line Items] | ||
| Percent of Net Asset Value | 4.70% | |
| C000007613 [Member] | Financial Services Sector [Member] | ||
| Holdings [Line Items] | ||
| Percent of Net Asset Value | 18.70% | |
| C000007613 [Member] | Healthcare Sector [Member] | ||
| Holdings [Line Items] | ||
| Percent of Net Asset Value | 11.10% | |
| C000007613 [Member] | Real Estate Sector [Member] | ||
| Holdings [Line Items] | ||
| Percent of Net Asset Value | 7.50% | |
| C000007613 [Member] | Communications Sector [Member] | ||
| Holdings [Line Items] | ||
| Percent of Net Asset Value | 3.40% | |
| C000007613 [Member] | Consumer Discretionary Sector [Member] | ||
| Holdings [Line Items] | ||
| Percent of Net Asset Value | 14.50% | |
| C000007613 [Member] | Consumer Staples Sector [Member] | ||
| Holdings [Line Items] | ||
| Percent of Net Asset Value | 3% | |
| C000007613 [Member] | Industrial Sector [Member] | ||
| Holdings [Line Items] | ||
| Percent of Net Asset Value | 17.50% | |
| C000007613 [Member] | Information Technology Sector [Member] | ||
| Holdings [Line Items] | ||
| Percent of Net Asset Value | 12% | |
| C000007613 [Member] | Materials Sector [Member] | ||
| Holdings [Line Items] | ||
| Percent of Net Asset Value | 4.40% | |
| C000007613 [Member] | Utilities Sector [Member] | ||
| Holdings [Line Items] | ||
| Percent of Net Asset Value | 2.20% | |
| C000007613 [Member] | Investment Companies [Member] | ||
| Holdings [Line Items] | ||
| Percent of Net Asset Value | 2.30% | |
| C000007613 [Member] | Net Other Assets and Liabilities [Member] | ||
| Holdings [Line Items] | ||
| Percent of Net Asset Value | (1.30%) | |
| C000007614 [Member] | NVIDIA Corp [Member] | ||
| Holdings [Line Items] | ||
| Percent of Net Asset Value | 8.20% | [4] |
| C000007614 [Member] | Taiwan Semiconductor Manufacturing Co Ltd ADR [Member] | ||
| Holdings [Line Items] | ||
| Percent of Net Asset Value | 7% | [4] |
| C000007614 [Member] | Amazon com Inc [Member] | ||
| Holdings [Line Items] | ||
| Percent of Net Asset Value | 4.90% | [4] |
| C000007614 [Member] | Microsoft Corp [Member] | ||
| Holdings [Line Items] | ||
| Percent of Net Asset Value | 4.80% | [4] |
| C000007614 [Member] | Shopify Inc Cl A [Member] | ||
| Holdings [Line Items] | ||
| Percent of Net Asset Value | 4.40% | [4] |
| C000007614 [Member] | Apple Inc [Member] | ||
| Holdings [Line Items] | ||
| Percent of Net Asset Value | 4.40% | [4] |
| C000007614 [Member] | ServiceNow Inc [Member] | ||
| Holdings [Line Items] | ||
| Percent of Net Asset Value | 4.30% | [4] |
| C000007614 [Member] | Alphabet Inc Cl C [Member] | ||
| Holdings [Line Items] | ||
| Percent of Net Asset Value | 4.20% | [4] |
| C000007614 [Member] | Netflix Inc [Member] | ||
| Holdings [Line Items] | ||
| Percent of Net Asset Value | 4.10% | [4] |
| C000007614 [Member] | Meta Platforms Inc Cl A [Member] | ||
| Holdings [Line Items] | ||
| Percent of Net Asset Value | 4.10% | [4] |
| C000007614 [Member] | Healthcare Sector [Member] | ||
| Holdings [Line Items] | ||
| Percent of Net Asset Value | 0.50% | |
| C000007614 [Member] | Real Estate Sector [Member] | ||
| Holdings [Line Items] | ||
| Percent of Net Asset Value | 1.80% | |
| C000007614 [Member] | Communications Sector [Member] | ||
| Holdings [Line Items] | ||
| Percent of Net Asset Value | 17.10% | |
| C000007614 [Member] | Consumer Discretionary Sector [Member] | ||
| Holdings [Line Items] | ||
| Percent of Net Asset Value | 7.40% | |
| C000007614 [Member] | Industrial Sector [Member] | ||
| Holdings [Line Items] | ||
| Percent of Net Asset Value | 2.50% | |
| C000007614 [Member] | Information Technology Sector [Member] | ||
| Holdings [Line Items] | ||
| Percent of Net Asset Value | 67.50% | |
| C000007614 [Member] | Investment Companies [Member] | ||
| Holdings [Line Items] | ||
| Percent of Net Asset Value | 4.20% | |
| C000007614 [Member] | Net Other Assets and Liabilities [Member] | ||
| Holdings [Line Items] | ||
| Percent of Net Asset Value | (1.00%) | |
| C000007615 [Member] | NVIDIA Corp [Member] | ||
| Holdings [Line Items] | ||
| Percent of Net Asset Value | 8.20% | [5] |
| C000007615 [Member] | Taiwan Semiconductor Manufacturing Co Ltd ADR [Member] | ||
| Holdings [Line Items] | ||
| Percent of Net Asset Value | 7% | [5] |
| C000007615 [Member] | Amazon com Inc [Member] | ||
| Holdings [Line Items] | ||
| Percent of Net Asset Value | 4.90% | [5] |
| C000007615 [Member] | Microsoft Corp [Member] | ||
| Holdings [Line Items] | ||
| Percent of Net Asset Value | 4.80% | [5] |
| C000007615 [Member] | Shopify Inc Cl A [Member] | ||
| Holdings [Line Items] | ||
| Percent of Net Asset Value | 4.40% | [5] |
| C000007615 [Member] | Apple Inc [Member] | ||
| Holdings [Line Items] | ||
| Percent of Net Asset Value | 4.40% | [5] |
| C000007615 [Member] | ServiceNow Inc [Member] | ||
| Holdings [Line Items] | ||
| Percent of Net Asset Value | 4.30% | [5] |
| C000007615 [Member] | Alphabet Inc Cl C [Member] | ||
| Holdings [Line Items] | ||
| Percent of Net Asset Value | 4.20% | [5] |
| C000007615 [Member] | Netflix Inc [Member] | ||
| Holdings [Line Items] | ||
| Percent of Net Asset Value | 4.10% | [5] |
| C000007615 [Member] | Meta Platforms Inc Cl A [Member] | ||
| Holdings [Line Items] | ||
| Percent of Net Asset Value | 4.10% | [5] |
| C000007615 [Member] | Healthcare Sector [Member] | ||
| Holdings [Line Items] | ||
| Percent of Net Asset Value | 0.50% | |
| C000007615 [Member] | Real Estate Sector [Member] | ||
| Holdings [Line Items] | ||
| Percent of Net Asset Value | 1.80% | |
| C000007615 [Member] | Communications Sector [Member] | ||
| Holdings [Line Items] | ||
| Percent of Net Asset Value | 17.10% | |
| C000007615 [Member] | Consumer Discretionary Sector [Member] | ||
| Holdings [Line Items] | ||
| Percent of Net Asset Value | 7.40% | |
| C000007615 [Member] | Industrial Sector [Member] | ||
| Holdings [Line Items] | ||
| Percent of Net Asset Value | 2.50% | |
| C000007615 [Member] | Information Technology Sector [Member] | ||
| Holdings [Line Items] | ||
| Percent of Net Asset Value | 67.50% | |
| C000007615 [Member] | Investment Companies [Member] | ||
| Holdings [Line Items] | ||
| Percent of Net Asset Value | 4.20% | |
| C000007615 [Member] | Net Other Assets and Liabilities [Member] | ||
| Holdings [Line Items] | ||
| Percent of Net Asset Value | (1.00%) | |
| [1]Excludes money market funds or other short-term securities held for the investment of cash and cash collateral for securities loaned, if any.[2]Excludes money market funds or other short-term securities held for the investment of cash and cash collateral for securities loaned, if any.[3]Excludes money market funds or other short-term securities held for the investment of cash and cash collateral for securities loaned, if any.[4]Excludes money market funds or other short-term securities held for the investment of cash and cash collateral for securities loaned, if any.[5]Excludes money market funds or other short-term securities held for the investment of cash and cash collateral for securities loaned, if any. | ||
