Reinsurance and Indemnification - Schedule of Effects of Reinsurance Ceded and Indemnification Programs on Property and Casualty Insurance Claims and Claims Expense and Accident, Health and Other Policy Benefits (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Property and casualty insurance claims and claims expense
Effects of Reinsurance [Line Items]
Reinsurance ceded amount	$ (1,716)	$ (633)	$ (1,600)
Accident, health and other policy benefits
Effects of Reinsurance [Line Items]
Reinsurance ceded amount	$ (36)	$ (44)	$ 15