Vanguard Total Bond Market Index Fund Average Annual Total Returns - Admiral Prospectus [Member] |
12 Months Ended | 60 Months Ended | 83 Months Ended | 120 Months Ended |
|---|---|---|---|---|
Dec. 31, 2025 |
Dec. 31, 2025 |
Dec. 31, 2025 |
Dec. 31, 2025 |
|
| 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%) | 1.90% | 2.05% |
| Admiral Shares | ||||
| Prospectus [Line Items] | ||||
| Average Annual Return, Percent | 7.15% | (0.42%) | 1.99% | |
| Admiral Shares | After Taxes on Distributions | ||||
| Prospectus [Line Items] | ||||
| Average Annual Return, Percent | 5.46% | (1.64%) | 0.82% | |
| Admiral Shares | After Taxes on Distributions and Sales | ||||
| Prospectus [Line Items] | ||||
| Average Annual Return, Percent | 4.21% | (0.84%) | 1.02% |