Vanguard Balanced Index Fund Average Annual Total Returns - Investor Prospectus [Member]	12 Months Ended	60 Months Ended	120 Months Ended
	Dec. 31, 2025	Dec. 31, 2025	Dec. 31, 2025
CRSP US Total Market Index (reflects no deduction for fees, expenses, or taxes)[Member]
Prospectus [Line Items]
Average Annual Return, Percent	17.15%	13.08%	14.25%
Bloomberg U.S. Aggregate Float Adjusted Index (reflects no deduction for fees, expenses, or taxes)[Member]
Prospectus [Line Items]
Average Annual Return, Percent	7.21%	(0.37%)	2.05%
Balanced Composite Index (reflects no deduction for fees, expenses, or taxes)[Member]
Prospectus [Line Items]
Average Annual Return, Percent	13.57%	7.89%	9.69%
Investor Shares
Prospectus [Line Items]
Average Annual Return, Percent	13.46%	7.64%	9.38%
Investor Shares \| After Taxes on Distributions
Prospectus [Line Items]
Average Annual Return, Percent	11.55%	6.35%	8.33%
Investor Shares \| After Taxes on Distributions and Sales
Prospectus [Line Items]
Average Annual Return, Percent	8.71%	5.65%	7.31%