Average Annual Total Returns |
12 Months Ended | 60 Months Ended | 120 Months Ended | 283 Months Ended | 536 Months Ended | ||||||
|---|---|---|---|---|---|---|---|---|---|---|---|
Dec. 31, 2024 |
Dec. 31, 2024 |
Dec. 31, 2024 |
Dec. 31, 2024 |
Dec. 31, 2024 |
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| Investment Shares | |||||||||||
| Prospectus [Line Items] | |||||||||||
| Average Annual Return, Percent | 4.62% | 2.05% | 1.33% | 3.80% | [1] | ||||||
| Performance Inception Date | May 12, 1980 | ||||||||||
| Retirement Shares | |||||||||||
| Prospectus [Line Items] | |||||||||||
| Average Annual Return, Percent | 4.61% | 2.05% | 1.32% | 1.16% | [2] | ||||||
| Performance Inception Date | May 21, 2001 | ||||||||||
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