Vanguard SP Mid-Cap 400 Index Fund Average Annual Total Returns - ETF Prospectus [Member] |
12 Months Ended | 60 Months Ended | 120 Months Ended |
|---|---|---|---|
Dec. 31, 2024 |
Dec. 31, 2024 |
Dec. 31, 2024 |
|
| S&P MidCap 400 Index (reflects no deduction for fees, expenses, or taxes)[Member] | |||
| Prospectus [Line Items] | |||
| Average Annual Return, Percent | 13.93% | 10.34% | 9.68% |
| Dow Jones U.S. Total Stock Market Float Adjusted Index (reflects no deduction for fees, expenses, or taxes)[Member] | |||
| Prospectus [Line Items] | |||
| Average Annual Return, Percent | 23.88% | 13.78% | 12.48% |
| ETF Shares | After Taxes on Distributions | |||
| Prospectus [Line Items] | |||
| Average Annual Return, Percent | 13.44% | 9.84% | 9.16% |
| ETF Shares | After Taxes on Distributions and Sales | |||
| Prospectus [Line Items] | |||
| Average Annual Return, Percent | 8.40% | 8.04% | 7.74% |
| ETF Shares | Based on NAV[Member] | |||
| Prospectus [Line Items] | |||
| Average Annual Return, Percent | 13.82% | 10.23% | 9.56% |
| ETF Shares | Based on Market Price[Member] | |||
| Prospectus [Line Items] | |||
| Average Annual Return, Percent | 13.75% | 10.23% | 9.56% |