S000010027 [Member] Annual Total Returns |
12 Months Ended | |||||||||
|---|---|---|---|---|---|---|---|---|---|---|
Dec. 31, 2025 |
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 |
|
| The MidCap Growth Fund | Shares | ||||||||||
| Prospectus [Line Items] | ||||||||||
| Annual Return [Percent] | 1.51% | 11.84% | 17.73% | (20.32%) | 19.32% | 23.72% | 34.36% | (4.35%) | 23.37% | 10.90% |