S000010778 [Member] 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 |
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| S000010778 [Member] | C000029792 [Member] | ||||||||||||
| Prospectus [Line Items] | ||||||||||||
| Annual Return [Percent] | [1] | 2.23% | 3.54% | (3.24%) | 0.31% | 1.70% | 2.84% | 1.19% | 1.28% | (0.19%) | 0.30% | |
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