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 |
|
| Admiral Prospectus [Member] | Vanguard Mortgage-Backed Securities Index Fund | Admiral Shares | ||||||||||
| Prospectus [Line Items] | ||||||||||
| Annual Return [Percent] | 1.44% | 4.99% | (11.56%) | (1.35%) | 3.74% | 6.16% | 0.86% | 2.32% | 1.47% | 1.44% |