Other Comprehensive Income (Loss) - Amounts reclassified from accumulated other comprehensive income (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2024	Jun. 30, 2023	Jun. 30, 2024	Jun. 30, 2023
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Provision for credit losses	$ 4	$ (7)	$ (2)	$ (23)
Income (loss) before income taxes and income (loss) from operating affiliates	1,321	714	2,487	1,456
Income tax (expense) benefit	(97)	(67)	(198)	(131)
Net of tax	1,269	669	2,389	1,386
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)	(64)	(147)	(92)	(241)
Provision for credit losses	4	(7)	(2)	(23)
Income (loss) before income taxes and income (loss) from operating affiliates	(60)	(154)	(94)	(264)
Income tax (expense) benefit	7	5	12	16
Net of tax	$ (53)	$ (149)	$ (82)	$ (248)