Reinsurance - Rollforward of the reinsurance recoverable allowance for credit losses (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Reinsurance Recoverable, Allowance for Credit Loss [Roll Forward]
Balance, beginning of period	$ 382	$ 375	$ 151
Initial allowance upon CECL adoption	0	0	224
Addition to (release of) allowance for expected credit losses and disputes, net	(39)	24	9
Write-offs charged against the allowance for credit losses and disputes	(5)	(17)	(9)
Recoveries of amounts previously written off	2	0	0
Other changes	4	0	0
Balance, end of period	344	382	375
General Insurance
Reinsurance Recoverable, Allowance for Credit Loss [Roll Forward]
Balance, beginning of period	281	292	111
Initial allowance upon CECL adoption	0	0	202
Addition to (release of) allowance for expected credit losses and disputes, net	(22)	6	(12)
Write-offs charged against the allowance for credit losses and disputes	(5)	(17)	(9)
Recoveries of amounts previously written off	2	0	0
Other changes	4	0	0
Balance, end of period	260	281	292
Life and Retirement
Reinsurance Recoverable, Allowance for Credit Loss [Roll Forward]
Balance, beginning of period	101	83	40
Initial allowance upon CECL adoption	0	0	22
Addition to (release of) allowance for expected credit losses and disputes, net	(17)	18	21
Write-offs charged against the allowance for credit losses and disputes	0	0	0
Recoveries of amounts previously written off	0	0	0
Other changes	0	0	0
Balance, end of period	$ 84	$ 101	$ 83