Summary of Significant Accounting Policies (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Accounting Policies [Abstract]
Unbilled Audit Premiums	$ 19	$ 19	$ 25
Weighted average shares held in grantor trust	17,659,297
Indefinite-lived Intangible Assets [Line Items]
Basic weighted average number of shares outstanding (in shares)	399,734	406,500	415,278
Deposit contracts, liabilities	$ 29	$ 31
Depreciation	55	51	$ 52
Interest payments	138	114	138
Income taxes paid	410	332	$ 295
Other Assets
Indefinite-lived Intangible Assets [Line Items]
Intangible assets, net (excluding goodwill)	$ 97	$ 119