Mid-Cap Index Portfolio Investment Objectives and Goals - Portfolio [Member] - Mid-Cap Index Portfolio |
Dec. 31, 2025 |
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| Prospectus [Line Items] | |
| Risk/Return [Heading] | <span style="font-family:Arial;font-size:13pt;font-weight:bold;">Fund Summary</span> |
| Objective [Heading] | <span style="color:#000000;font-family:Arial;font-size:10pt;font-weight:bold;">Investment Objective</span> |
| Objective, Primary [Text Block] | Vanguard Variable Insurance Funds Mid-Cap Index Portfolio (the “Fund”) seeks to track the performance of a benchmark index that measures the investment return of mid-capitalization stocks. |