Reinsurance and Indemnification - Schedule of Rollforward of Credit Loss Allowance for Reinsurance Recoverables (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Property and casualty
Reinsurance Recoverable, Allowance for Credit Loss [Roll Forward]
Beginning balance	$ (62)	$ (62)
(Increase) decrease in the provision for credit losses	(2)	1
Write-offs	0	0
Ending balance	(64)	(61)
Accident and health insurance
Reinsurance Recoverable, Allowance for Credit Loss [Roll Forward]
Beginning balance	(3)	(3)
(Increase) decrease in the provision for credit losses	0	0
Write-offs	0	0
Ending balance	$ (3)	$ (3)