Reinsurance - Rollforward of the Reinsurance Recoverable Allowance for Credit Losses (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2025	Sep. 30, 2024	Sep. 30, 2025	Sep. 30, 2024
Reinsurance Recoverable, Allowance for Credit Loss [Roll Forward]
Balance, beginning of period	$ 276	$ 260	$ 269	$ 255
Addition to (release of) allowance for expected credit losses and disputes, net	0	9	(1)	9
Write-offs charged against the allowance for credit losses and disputes	0	0	(1)	(1)
Other changes	(1)	3	8	9
Balance, end of period	$ 275	$ 272	$ 275	$ 272