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Vanguard SP Small-Cap 600 Index Fund Average Annual Total Returns - Institutional Prospectus [Member]
12 Months Ended 60 Months Ended 69 Months Ended 118 Months Ended 120 Months Ended
Dec. 31, 2024
Dec. 31, 2024
Dec. 31, 2024
Dec. 31, 2024
Dec. 31, 2024
S&P SmallCap 600 Index (reflects no deduction for fees, expenses, or taxes)[Member]          
Prospectus [Line Items]          
Average Annual Return, Percent 8.70% 8.36%     8.96%
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% 14.20% 12.36% 12.48%
Institutional Shares          
Prospectus [Line Items]          
Average Annual Return, Percent 8.63% 8.33%     8.94%
Institutional Shares | After Taxes on Distributions          
Prospectus [Line Items]          
Average Annual Return, Percent 8.23% 7.95%     8.57%
Institutional Shares | After Taxes on Distributions and Sales          
Prospectus [Line Items]          
Average Annual Return, Percent 5.35% 6.50%     7.23%