Fair Value Measurements - Difference Between the Aggregate Fair Value and the Aggregate Unpaid Principal Balance for Residential Mortgage Loans Measured at Fair Value (Details) - Residential mortgage loans - USD ($) $ in Millions |
Jun. 30, 2025 |
Dec. 31, 2024 |
|---|---|---|
| Aggregate Fair Value | ||
| Residential mortgage loans measured at fair value | $ 679 | $ 682 |
| Past due loans of 30-89 days | 1 | 1 |
| Past due loans of 90 days or more | 1 | 1 |
| Nonaccrual loans | 2 | 2 |
| Aggregate Unpaid Principal Balance | ||
| Residential mortgage loans measured at fair value | 677 | 693 |
| Past due loans of 30-89 days | 1 | 1 |
| Past due loans of 90 days or more | 1 | 1 |
| Nonaccrual loans | $ 2 | $ 2 |