Vanguard Long-Term Treasury Index Fund Annual Total Returns |
12 Months Ended | |||||||||
|---|---|---|---|---|---|---|---|---|---|---|
Dec. 31, 2024 |
Dec. 31, 2023 |
Dec. 31, 2022 |
Dec. 31, 2021 |
Dec. 31, 2020 |
Dec. 31, 2019 |
Dec. 31, 2018 |
Dec. 31, 2017 |
Dec. 31, 2016 |
Dec. 31, 2015 |
|
| Institutional Prospectus [Member] | Vanguard Long-Term Treasury Index Fund | Institutional Shares | ||||||||||
| Prospectus [Line Items] | ||||||||||
| Annual Return [Percent] | (6.46%) | 3.70% | (29.45%) | (5.04%) | 17.72% | 14.30% | (1.63%) | 8.67% | 1.38% | (1.32%) |