Related Party Transactions Narrative (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022		Dec. 31, 2021
Other liabilities	$ 2,897	$ 2,983	[1]
Other assets	2,534	2,274	[1]
Net earned premiums	9,480	8,667	[1]	$ 8,175	[1]
Related Party
Other liabilities	28	26
Other assets	23	18
Related Party | Fees and expenses of investment facilities and services
Related party transaction, amounts of transaction	55	51		47
Related Party | Corporate services and related travel expenses
Related party transaction, amounts of transaction	1	1
Related Party | Loews
Net earned premiums	$ 2	$ 3		$ 2

[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.