Reinsurance and Indemnification - Rollforward of credit loss allowance for reinsurance recoverables (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2023	Mar. 31, 2022
Property and casualty
Reinsurance Recoverable, Allowance for Credit Loss [Roll Forward]
Beginning balance	$ (62)	$ (66)
Decrease (increase) in the provision for credit losses	1	0
Write-offs	0	0
Ending balance	(61)	(66)
Accident and health insurance
Reinsurance Recoverable, Allowance for Credit Loss [Roll Forward]
Beginning balance	(3)	(8)
Decrease (increase) in the provision for credit losses	0	0
Write-offs	0	0
Ending balance	$ (3)	$ (8)