Investments - Hybrid Securities (Detail) - USD ($) $ in Millions |
Sep. 30, 2026 |
Dec. 31, 2025 |
Sep. 30, 2025 |
|---|---|---|---|
| Hybrid Instruments [Line Items] | |||
| Hybrid securities | $ 1,337 | $ 1,525 | $ 1,338 |
| Corporate and other debt | |||
| Hybrid Instruments [Line Items] | |||
| Hybrid securities | 643 | 733 | 696 |
| Residential mortgage-backed | |||
| Hybrid Instruments [Line Items] | |||
| Hybrid securities | $ 694 | $ 792 | $ 642 |