Investments - Gross realized gains and gross realized losses from sales or maturities of available for sale securities (Details) - USD ($) $ in Millions |
12 Months Ended | ||
|---|---|---|---|
Dec. 31, 2023 |
Dec. 31, 2022 |
Dec. 31, 2021 |
|
| Investments, Debt and Equity Securities [Abstract] | |||
| Gross Realized Gains | $ 267 | $ 446 | $ 1,369 |
| Gross Realized Losses | 1,329 | 1,628 | 441 |
| Aggregate fair value of available for sale securities sold | 23,600 | 20,500 | 27,300 |
| Net Investment Income [Line Items] | |||
| Net realized gains (losses) | (1,100) | (1,200) | 928 |
| Fortitude RE Funds Withheld Assets | |||
| Net Investment Income [Line Items] | |||
| Net realized gains (losses) | $ (133) | $ (311) | $ 717 |