Reinsurance - Supplemental Information for Loss and Benefit Reserves, Gross and Net of Ceded Reinsurance (Details) - USD ($) $ in Millions	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
As Reported
Liability for unpaid losses and loss adjustment expenses	$ (69,168)	$ (70,393)	$ (75,167)	$ (79,026)
Future policy benefits	(1,317)	(1,467)
Unearned premiums	(17,232)	(17,375)
Other policyholder funds	(418)	(495)
Reinsurance assets	34,166	35,492
Net of Reinsurance
Liability for unpaid losses and loss adjustment expenses	(40,032)	(39,994)
Future policy benefits	(591)	(644)
Reserve for unearned premiums	(12,928)	(13,105)
Other policyholder funds	(418)	(495)
Reinsurance asset, allowance for credit loss	220	206
Reserve for liability to unpaid losses	110	110
Loss Recoveries
Net of Reinsurance
Contract claim recoverables	4,068	3,819
Contract Claims Recoverable
Net of Reinsurance
Contract claim recoverables	$ 31	$ 27