Vanguard SP Mid-Cap 400 Growth 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 Growth Index (reflects no deduction for fees, expenses, or taxes)[Member]
Prospectus [Line Items]
Average Annual Return, Percent	15.94%	10.01%	9.86%
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	15.56%	9.63%	9.43%
ETF Shares \| After Taxes on Distributions and Sales
Prospectus [Line Items]
Average Annual Return, Percent	9.49%	7.78%	7.91%
ETF Shares \| Based on NAV[Member]
Prospectus [Line Items]
Average Annual Return, Percent	15.78%	9.85%	9.70%
ETF Shares \| Based on Market Price[Member]
Prospectus [Line Items]
Average Annual Return, Percent	15.69%	9.84%	9.68%