Insurance Liabilities - Net loss reserve discount benefit (charge) (Details) - USD ($) $ in Millions |
12 Months Ended | ||
|---|---|---|---|
Dec. 31, 2023 |
Dec. 31, 2022 |
Dec. 31, 2021 |
|
| Net Loss Reserve Discount Benefit (Charge) [Line Items] | |||
| Current accident year | $ 112 | $ 98 | $ 62 |
| Accretion and other adjustments to prior year discount | (264) | (239) | (88) |
| Net reserve discount benefit (charge) | (195) | 703 | 193 |
| Change in discount on loss reserves ceded under retroactive reinsurance | 150 | (301) | (42) |
| Net change in total reserve discount | (45) | 402 | 151 |
| North America Commercial Insurance | |||
| Net Loss Reserve Discount Benefit (Charge) [Line Items] | |||
| Effect of interest rate changes | (43) | 844 | 219 |
| United Kingdom | |||
| Net Loss Reserve Discount Benefit (Charge) [Line Items] | |||
| Net change in total reserve discount | $ 61 | $ 19 | $ (35) |