S000003867 [Member] Performance Management - BlackRock Capital Appreciation Portfolio |
Dec. 31, 2025 |
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| Prospectus [Line Items] | |
| Bar Chart and Performance Table [Heading] | Performance Information |
| Performance Narrative [Text Block] | The information shows you how the Fund’s performance has varied year by year and provides some indication of the risks of investing in the Fund. The table compares the Fund’s performance to that of the S&P 500® Index and the Russell 1000® Growth Index, which are relevant to the Fund because they have characteristics similar to the Fund’s investment strategies. To the extent that dividends and distributions have been paid by the Fund, the performance information for the Fund in the chart and table assumes reinvestment of the dividends and distributions. As with all such investments, past performance is not an indication of future results. The bar chart and table do not reflect separate account fees and expenses. If they did, returns would be less than those shown. If the Fund’s investment manager and its affiliates had not waived or reimbursed certain Fund expenses during these periods, the Fund’s returns would have been lower.
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| Performance Past Does Not Indicate Future [Text] | As with all such investments, past performance is not an indication of future results. |
| Performance Information Illustrates Variability of Returns [Text] | The information shows you how the Fund’s performance has varied year by year and provides some indication of the risks of investing in the Fund. |
| Performance Additional Market Index [Text] | The table compares the Fund’s performance to that of the S&P 500® Index and the Russell 1000® Growth Index, which are relevant to the Fund because they have characteristics similar to the Fund’s investment strategies. |
| Bar Chart Does Not Reflect Sales Loads [Text] | The bar chart and table do not reflect separate account fees and expenses. If they did, returns would be less than those shown. |
| Bar Chart [Heading] | ANNUAL TOTAL RETURNS BlackRock Capital Appreciation Portfolio As of 12/31 |
| Bar Chart Closing [Text Block] | During the ten‑year period shown in the bar chart, the highest return for a quarter was 29.04% (quarter ended June 30, 2020) and the lowest return for a quarter was -23.10% (quarter ended June 30, 2022).
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| Performance Table Heading | For the periods ended 12/31/25Average Annual Total Returns |
| BlackRock Capital Appreciation Portfolio | |
| Prospectus [Line Items] | |
| Highest Quarterly Return, Label [Optional Text] | highest return |
| Highest Quarterly Return | 29.04% |
| Highest Quarterly Return, Date | Jun. 30, 2020 |
| Lowest Quarterly Return, Label [Optional Text] | lowest return |
| Lowest Quarterly Return | (23.10%) |
| Lowest Quarterly Return, Date | Jun. 30, 2022 |