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Vanguard Russell 2000 Index Fund Average Annual Total Returns - Institutional Prospectus [Member]
12 Months Ended 60 Months Ended 120 Months Ended
Dec. 31, 2024
Dec. 31, 2024
Dec. 31, 2024
Russell 2000 Index (reflects no deduction for fees, expenses, or taxes)[Member]      
Prospectus [Line Items]      
Average Annual Return, Percent 11.54% 7.40% 7.82%
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%
Institutional Shares      
Prospectus [Line Items]      
Average Annual Return, Percent 11.58% 7.48% 7.90%
Institutional Shares | After Taxes on Distributions      
Prospectus [Line Items]      
Average Annual Return, Percent 11.21% 7.09% 7.49%
Institutional Shares | After Taxes on Distributions and Sales      
Prospectus [Line Items]      
Average Annual Return, Percent 7.04% 5.78% 6.29%