Vanguard SP Mid-Cap 400 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 SP Mid-Cap 400 Index Fund | Institutional Shares | ||||||||||
| Prospectus [Line Items] | ||||||||||
| Annual Return [Percent] | 13.85% | 16.36% | (13.11%) | 24.67% | 13.58% | 26.13% | (11.14%) | 16.18% | 20.66% | (2.23%) |