Vanguard Institutional Index Fund Annual Fund Operating Expenses - Institutional Prospectus [Member] - Vanguard Institutional Index Fund |
Dec. 31, 2025 |
|---|---|
| Institutional Shares | |
| Prospectus [Line Items] | |
| Management Fees (as a percentage of Assets) | 0.031% |
| Distribution and Service (12b-1) Fees | 0.00% |
| Other Expenses (as a percentage of Assets): | 0.004% |
| Expenses (as a percentage of Assets) | 0.035% |
| Institutional Plus Shares | |
| Prospectus [Line Items] | |
| Management Fees (as a percentage of Assets) | 0.02% |
| Distribution and Service (12b-1) Fees | 0.00% |
| Other Expenses (as a percentage of Assets): | 0.00% |
| Expenses (as a percentage of Assets) | 0.02% |