Summary of Significant Accounting Policies (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Accounting Policies [Abstract]
Unbilled Audit Premiums	$ 19	$ 25	$ 10
Weighted average shares held in grantor trust	11,663,450
Indefinite-lived Intangible Assets [Line Items]
Basic weighted average number of shares outstanding (in shares)	271,000	276,852	277,430
Deposit contracts, liabilities	$ 31	$ 33
Depreciation	51	52	$ 52
Interest payments	114	138	141
Income taxes paid	332	295	$ 244
Other Assets
Indefinite-lived Intangible Assets [Line Items]
Intangible assets, net (excluding goodwill)	$ 119	$ 102