Reinsurance - Rollforward of the reinsurance recoverable allowance for credit losses (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Reinsurance Recoverable, Allowance for Credit Loss [Roll Forward]
Balance, beginning of period	$ 344	$ 382	$ 375
Addition to (release of) allowance for expected credit losses and disputes, net	(10)	(39)	24
Write-offs charged against the allowance for credit losses and disputes	(49)	(5)	(17)
Recoveries of amounts previously written off	0	2
Other changes	0	4
Balance, end of period	285	344	382
General Insurance
Reinsurance Recoverable, Allowance for Credit Loss [Roll Forward]
Balance, beginning of period	260	281	292
Addition to (release of) allowance for expected credit losses and disputes, net	(5)	(22)	6
Write-offs charged against the allowance for credit losses and disputes	0	(5)	(17)
Recoveries of amounts previously written off	0	2
Other changes	0	4
Balance, end of period	255	260	281
Life and Retirement
Reinsurance Recoverable, Allowance for Credit Loss [Roll Forward]
Balance, beginning of period	84	101	83
Addition to (release of) allowance for expected credit losses and disputes, net	(5)	(17)	18
Write-offs charged against the allowance for credit losses and disputes	(49)	0
Recoveries of amounts previously written off	0	0
Other changes	0	0
Balance, end of period	$ 30	$ 84	$ 101