Fair Value (Carrying amount and estimated fair value of financial instrument assets and liabilities which are not measured at fair value) (Details) - USD ($) $ in Millions |
Mar. 31, 2026 |
Dec. 31, 2025 |
|---|---|---|
| Assets | ||
| Mortgage loans | $ 1,055 | $ 1,079 |
| Liabilities | ||
| Long-term debt | 2,972 | 2,971 |
| Carrying Amount | ||
| Assets | ||
| Mortgage loans | 1,055 | 1,079 |
| Liabilities | ||
| Long-term debt | 2,972 | 2,971 |
| Estimated Fair Value | ||
| Assets | ||
| Mortgage loans | 1,043 | 1,072 |
| Liabilities | ||
| Long-term debt | 2,917 | 2,967 |
| Level 1 | Estimated Fair Value | ||
| Assets | ||
| Mortgage loans | 0 | 0 |
| Liabilities | ||
| Long-term debt | 0 | 0 |
| Level 2 | Estimated Fair Value | ||
| Assets | ||
| Mortgage loans | 0 | 0 |
| Liabilities | ||
| Long-term debt | 2,917 | 2,967 |
| Level 3 | Estimated Fair Value | ||
| Assets | ||
| Mortgage loans | 1,043 | 1,072 |
| Liabilities | ||
| Long-term debt | $ 0 | $ 0 |