Long-Term US Government Bond Portfolio Average Annual Total Returns |
12 Months Ended | 60 Months Ended | 120 Months Ended |
|---|---|---|---|
Dec. 31, 2025 |
Dec. 31, 2025 |
Dec. 31, 2025 |
|
| Bloomberg® Long-Term Treasury Index[Member] | |||
| Prospectus [Line Items] | |||
| Average Annual Return, Percent | 5.59% | (7.23%) | 0.02% |
| Bloomberg® U.S. Aggregate Bond Index(reflects no deduction for fees, expenses or taxes)[Member] | |||
| Prospectus [Line Items] | |||
| Average Annual Return, Percent | 7.30% | (0.36%) | 2.01% |
| Long-Term US Government Bond Portfolio | |||
| Prospectus [Line Items] | |||
| Average Annual Return, Percent | 6.15% | (7.18%) | (0.19%) |