Allowance for Expected Credit Losses - Reinsurance recoverables (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2024	Sep. 30, 2023
Credit Loss [Abstract]
Balance at beginning of period	$ 7,473	$ 6,717	$ 7,064	$ 6,564
Balance at end of period	7,948	6,821	7,948	6,821
Allowance for Expected Credit Losses
Balance at beginning of period	20	22	21	22
Change for provision of expected credit losses	(3)	1	(4)	1
Balance at end of period	$ 17	$ 23	$ 17	$ 23