Reinsurance (Reinsurance Recoverable on Ceded Reinsurance) (Details) - USD ($) $ in Millions		Sep. 30, 2022	Dec. 31, 2021	Sep. 30, 2021	Dec. 31, 2020
Reinsurance Disclosures [Abstract]
Reinsurance recoverable on unpaid losses and loss expenses	[1]	$ 17,380	$ 16,184	$ 15,550	$ 14,647
Reinsurance recoverable on paid losses and loss expenses	[1]	1,374	1,182
Reinsurance recoverable on losses and loss expenses	[1]	18,754	17,366
Reinsurance recoverable on policy benefits	[1]	297	213
Reinsurance Recoverables on Unpaid Losses, Allowance		297	271
Reinsurance Recoverables on Paid Losses, Allowance		55	58
Reinsurance Recoverable, Allowance for Credit Loss, Total		352	329	$ 325	$ 314
Reinsurance Recoverables on Future Policy Benefits, Allowance		$ 4	$ 4

[1] Net of valuation allowance for uncollectible reinsurance.