Allowance for Expected Credit Losses - Reinsurance recoverables (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2024	Jun. 30, 2023	Jun. 30, 2024	Jun. 30, 2023
Credit Loss [Abstract]
Balance at beginning of period	$ 7,509	$ 6,612	$ 7,064	$ 6,564
Balance at end of period	7,473	6,717	7,473	6,717
Allowance for Expected Credit Losses
Balance at beginning of period	16	21	21	22
Change for provision of expected credit losses	4	1	(1)	0
Balance at end of period	$ 20	$ 22	$ 20	$ 22