Unearned revenue liability (URL Rollforward) (Details) - USD ($) $ in Millions |
9 Months Ended | |
|---|---|---|
Sep. 30, 2026 |
Sep. 30, 2025 |
|
| Insurance [Abstract] | ||
| Balance – beginning of period | $ 758 | $ 711 |
| Deferred revenue | 91 | 101 |
| Amortization | (61) | (58) |
| Other (including foreign exchange) | 6 | 6 |
| Balance – end of period | $ 794 | $ 760 |