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Vanguard Russell 2000 Growth 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 Growth Index (reflects no deduction for fees, expenses, or taxes)[Member]      
Prospectus [Line Items]      
Average Annual Return, Percent 15.15% 6.86% 8.09%
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 15.25% 6.96% 8.22%
Institutional Shares | After Taxes on Distributions      
Prospectus [Line Items]      
Average Annual Return, Percent 15.07% 6.76% 7.98%
Institutional Shares | After Taxes on Distributions and Sales      
Prospectus [Line Items]      
Average Annual Return, Percent 9.14% 5.42% 6.63%