Reinsurance (Components of Reinsurance Receivables) (Details) - USD ($) $ in Millions	Dec. 31, 2023	Dec. 31, 2022		Dec. 31, 2021	Dec. 31, 2020
Reinsurance receivables related to insurance reserves
Ceded claim and claim adjustment expenses	$ 5,141	$ 5,191		$ 4,969	$ 4,005
Reinsurance receivables related to paid losses	293	247
Reinsurance receivables	5,434	5,438		$ 5,484
Allowance for uncollectible reinsurance	(22)	(22)
Reinsurance receivables, net of allowance for uncollectible reinsurance	$ 5,412	$ 5,416	[1]

[1] As of January 1, 2023, the Company adopted ASU 2018-12, Financial Services-Insurance (Topic 944): Targeted Improvements to the Accounting for Long-Duration Contracts (ASU 2018-12) using the modified retrospective method applied as of the transition date of January 1, 2021. Prior period amounts in the financial statements have been adjusted to reflect application of the new guidance. See Note A to the Consolidated Financial Statements for additional information.