Reinsurance and Indemnification - Schedule of Rollforward of Credit Loss Allowance for Reinsurance Recoverables (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2024	Sep. 30, 2023
Property and casualty
Reinsurance Recoverable, Allowance for Credit Loss [Roll Forward]
Beginning balance	$ (64)	$ (61)	$ (62)	$ (62)
Decrease (increase) in the provision for credit losses	2	0	0	1
Write-offs	0	0	0	0
Ending balance	(62)	(61)	(62)	(61)
Accident and health insurance
Reinsurance Recoverable, Allowance for Credit Loss [Roll Forward]
Beginning balance	(3)	(3)	(3)	(3)
Decrease (increase) in the provision for credit losses	0	0	0	0
Write-offs	0	0	0	0
Reinsurance recoverables classified as held for sale	1	0	1	0
Ending balance	$ (2)	$ (3)	$ (2)	$ (3)