Vanguard Total Bond Market II Index Fund Average Annual Total Returns - Institutional Prospectus [Member] |
12 Months Ended | 60 Months Ended | 120 Months Ended |
|---|---|---|---|
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%) | 2.05% |
| Institutional Shares | |||
| Prospectus [Line Items] | |||
| Average Annual Return, Percent | 7.17% | (0.40%) | 1.97% |
| Institutional Shares | After Taxes on Distributions | |||
| Prospectus [Line Items] | |||
| Average Annual Return, Percent | 5.44% | (1.63%) | 0.77% |
| Institutional Shares | After Taxes on Distributions and Sales | |||
| Prospectus [Line Items] | |||
| Average Annual Return, Percent | 4.22% | (0.83%) | 1.00% |