Vanguard Intermediate-Term Bond 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 |
|
| Bloomberg U.S. 5-10 Year Gov/Credit Float Adjusted Index (reflects no deduction for fees, expenses, or taxes)[Member] | |||
| Prospectus [Line Items] | |||
| Average Annual Return, Percent | 8.76% | (0.15%) | 2.55% |
| 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% |
| Investor Shares | |||
| Prospectus [Line Items] | |||
| Average Annual Return, Percent | 8.46% | (0.29%) | 2.39% |
| Investor Shares | After Taxes on Distributions | |||
| Prospectus [Line Items] | |||
| Average Annual Return, Percent | 6.72% | (1.54%) | 1.18% |
| Investor Shares | After Taxes on Distributions and Sales | |||
| Prospectus [Line Items] | |||
| Average Annual Return, Percent | 4.98% | (0.73%) | 1.33% |