Other Comprehensive Income (Loss) - Amounts reclassified from accumulated other comprehensive income (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Provision for credit losses	$ 0	$ 9	$ (23)	$ (48)
Income (loss) before income taxes and income (loss) from operating affiliates	741	(6)	2,197	600
Income tax (expense) benefit	(72)	15	(203)	(19)
Net of tax	723	18	2,109	620
Reclassification out of accumulated other comprehensive income | Unrealized appreciation (decline) on available-for-sale investments
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Net realized gains (losses)	(104)	(56)	(345)	(186)
Provision for credit losses	0	9	(23)	(48)
Income (loss) before income taxes and income (loss) from operating affiliates	(104)	(47)	(368)	(234)
Income tax (expense) benefit	8	1	24	28
Net of tax	$ (96)	$ (46)	$ (344)	$ (206)