Reinsurance and Indemnification - Rollforward of credit loss allowance for reinsurance recoverables (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022
Property and casualty
Reinsurance Recoverable, Allowance for Credit Loss [Roll Forward]
Beginning balance	$ (61)	$ (66)	$ (62)	$ (66)
(Decrease) increase in the provision for credit losses	0	0	1	0
Write-offs	0	0	0	0
Ending balance	(61)	(66)	(61)	(66)
Accident and health insurance
Reinsurance Recoverable, Allowance for Credit Loss [Roll Forward]
Beginning balance	(3)	(8)	(3)	(8)
(Decrease) increase in the provision for credit losses	0	0	0	0
Write-offs	0	0	0	0
Ending balance	$ (3)	$ (8)	$ (3)	$ (8)