Separate accounts (Fair value of assets) (Details) - USD ($) $ in Millions |
Sep. 30, 2026 |
Dec. 31, 2025 |
Sep. 30, 2025 |
|---|---|---|---|
| Fair Value, Separate Account Investment [Line Items] | |||
| Separate account assets | $ 7,340 | $ 6,925 | $ 6,810 |
| Separate Account, Cash and Cash Equivalents | |||
| Fair Value, Separate Account Investment [Line Items] | |||
| Separate account assets | 133 | 103 | |
| Mutual funds | |||
| Fair Value, Separate Account Investment [Line Items] | |||
| Separate account assets | 7,134 | 6,631 | |
| Fixed maturities | |||
| Fair Value, Separate Account Investment [Line Items] | |||
| Separate account assets | $ 73 | $ 76 |