Investments Allowance for Credit Losses (Details) - USD ($) $ in Millions |
3 Months Ended | |||
|---|---|---|---|---|
Mar. 31, 2025 |
Mar. 31, 2024 |
Dec. 31, 2024 |
Dec. 31, 2023 |
|
| Allowance for Credit Loss [Abstract] | ||||
| (Charge-offs)/recoveries | $ (1) | $ (1) | ||
| Provision for/(reversal of) credit losses | 1 | (4) | ||
| Debt securities, available-for-sale, amortized cost, allowance for credit loss, excluding accrued interest | $ 30 | $ 26 | $ 30 | $ 31 |