Vanguard Long-Term Investment-Grade Fund Average Annual Total Returns - Retail Prospectus [Member] |
12 Months Ended | 60 Months Ended | 120 Months Ended |
|---|---|---|---|
Dec. 31, 2025 |
Dec. 31, 2025 |
Dec. 31, 2025 |
|
| Bloomberg U.S. Long Credit A or Better Bond Index (reflects no deduction for fees, expenses, or taxes)[Member] | |||
| Prospectus [Line Items] | |||
| Average Annual Return, Percent | 7.54% | (3.69%) | 2.59% |
| Bloomberg U.S. Aggregate Bond Index (reflects no deduction for fees, expenses, or taxes)[Member] | |||
| Prospectus [Line Items] | |||
| Average Annual Return, Percent | 7.30% | (0.36%) | 2.01% |
| Investor Shares | |||
| Prospectus [Line Items] | |||
| Average Annual Return, Percent | 7.18% | (3.74%) | 2.68% |
| Investor Shares | After Taxes on Distributions | |||
| Prospectus [Line Items] | |||
| Average Annual Return, Percent | 5.04% | (5.52%) | 0.66% |
| Investor Shares | After Taxes on Distributions and Sales | |||
| Prospectus [Line Items] | |||
| Average Annual Return, Percent | 4.22% | (3.46%) | 1.32% |
| Admiral Shares | |||
| Prospectus [Line Items] | |||
| Average Annual Return, Percent | 7.30% | (3.64%) | 2.79% |