Vanguard Mortgage-Backed Securities 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 Mortgage-Backed Securities Index Fund | Institutional Shares | ||||||||||
| Prospectus [Line Items] | ||||||||||
| Annual Return [Percent] | 1.42% | 5.01% | (11.56%) | (1.30%) | 3.77% | 6.18% | 0.88% | 2.38% | 1.47% | 1.44% |