Reinsurance - Rollforward of the reinsurance recoverable allowance for credit losses (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Reinsurance Recoverable, Allowance for Credit Loss [Roll Forward]
Balance, beginning of period	$ 320	$ 391	$ 344	$ 382
Addition to (release of) allowance for expected credit losses and disputes, net	5	5	(17)	12
Write-offs charged against the allowance for credit losses and disputes	0	(1)	(1)	(3)
Recoveries of amounts previously written off			0	2
Other changes	(1)	(1)	(2)	1
Balance, end of period	324	394	324	394
General Insurance
Reinsurance Recoverable, Allowance for Credit Loss [Roll Forward]
Balance, beginning of period	254	284	260	281
Addition to (release of) allowance for expected credit losses and disputes, net	1	4	(3)	5
Write-offs charged against the allowance for credit losses and disputes	0	(1)	(1)	(3)
Recoveries of amounts previously written off			0	2
Other changes	(1)	(1)	(2)	1
Balance, end of period	254	286	254	286
Life and Retirement
Reinsurance Recoverable, Allowance for Credit Loss [Roll Forward]
Balance, beginning of period	66	107	84	101
Addition to (release of) allowance for expected credit losses and disputes, net	4	1	(14)	7
Write-offs charged against the allowance for credit losses and disputes	0	0	0	0
Recoveries of amounts previously written off			0	0
Other changes	0	0	0	0
Balance, end of period	$ 70	$ 108	$ 70	$ 108