Vanguard Total Bond Market Index Fund Average Annual Total Returns - Institutional Select Prospectus [Member] |
12 Months Ended | 60 Months Ended | 114 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%) | 1.64% | |
| Institutional Select Shares | ||||
| Prospectus [Line Items] | ||||
| Average Annual Return, Percent | 7.18% | (0.38%) | 1.62% | |
| Performance Inception Date | Jun. 24, 2016 | |||
| Institutional Select Shares | After Taxes on Distributions | ||||
| Prospectus [Line Items] | ||||
| Average Annual Return, Percent | 5.48% | (1.62%) | 0.43% | |
| Institutional Select Shares | After Taxes on Distributions and Sales | ||||
| Prospectus [Line Items] | ||||
| Average Annual Return, Percent | 4.23% | (0.82%) | 0.72% |