Reinsurance and Indemnification - Schedule of Effects of Reinsurance Ceded and Indemnification Programs on Property and Casualty Premiums Earned and Accident and Health Insurance Premiums and Contract Charges (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Property and casualty insurance premiums
Reinsurance
Property and casualty insurance premiums earned	$ (557)	$ (446)
Accident and health insurance premiums and contract charges
Reinsurance
Accident and health insurance premiums and contract charges	$ (10)	$ (9)