Vanguard Institutional Index Fund Expense Example - Institutional Prospectus [Member] - Vanguard Institutional Index Fund |
Dec. 31, 2025
USD ($)
|
|---|---|
| Institutional Shares | |
| Prospectus [Line Items] | |
| Expense Example, with Redemption, 1 Year | $ 4 |
| Expense Example, with Redemption, 3 Years | 11 |
| Expense Example, with Redemption, 5 Years | 20 |
| Expense Example, with Redemption, 10 Years | 45 |
| Institutional Plus Shares | |
| Prospectus [Line Items] | |
| Expense Example, with Redemption, 1 Year | 2 |
| Expense Example, with Redemption, 3 Years | 6 |
| Expense Example, with Redemption, 5 Years | 11 |
| Expense Example, with Redemption, 10 Years | $ 26 |