Reinsurance, Allowance (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Reinsurance Disclosures [Abstract]
Valuation allowance for uncollectible reinsurance	$ 351	$ 329	$ 314
Provision for uncollectible reinsurance	43	66
Write-offs charged against the valuation allowance	(19)	(50)
Foreign exchange revaluation	$ (2)	$ (1)