Reinsurance and Indemnification - Schedule of Rollforward of Credit Loss Allowance for Reinsurance Recoverables (Details) - Property and casualty - 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]
Beginning balance	$ (63)	$ (64)	$ (63)	$ (62)
(Increase) decrease in the provision for credit losses	(1)	2	(1)	0
Write-offs	10	0	10	0
Ending balance	$ (54)	$ (62)	$ (54)	$ (62)