S000002875 [Member] Performance Management - BlackRock S&P 500 Index V.I. Fund |
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. Separate account fees and expenses are not reflected in the bar chart. If they did, returns would be less than those shown. The returns for Class III Shares prior to February 14, 2018, the recommencement of Class III Shares, are based upon performance of the Fund’s Class I Shares, as adjusted to reflect the distribution and/or service (12b‑1) fees applicable to Class III Shares. This information may be considered when assessing the performance of Class III Shares, but does not represent the actual performance of Class III Shares. 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. 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. |
| Bar Chart Does Not Reflect Sales Loads [Text] | Separate account fees and expenses are not reflected in the bar chart. If they did, returns would be less than those shown. |
| Bar Chart [Heading] | Class I Shares ANNUAL TOTAL RETURNS BlackRock S&P 500 Index V.I. Fund 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 20.51% (quarter ended June 30, 2020) and the lowest return for a quarter was –19.65% (quarter ended March 31, 2020).
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| Performance Table Heading | For the periods ended 12/31/25Average Annual Total Returns |
| Class I | |
| Prospectus [Line Items] | |
| Highest Quarterly Return, Label [Optional Text] | highest return |
| Highest Quarterly Return | 20.51% |
| Highest Quarterly Return, Date | Jun. 30, 2020 |
| Lowest Quarterly Return, Label [Optional Text] | lowest return |
| Lowest Quarterly Return | (19.65%) |
| Lowest Quarterly Return, Date | Mar. 31, 2020 |