Claim and Claim Adjustment Expense Reserves (International - Net prior year claim and allocated claim adjustment expense reserve development) (Details) - International - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Liability for Claims and Claims Adjustment Expense [Line Items]
Commercial	$ (18)	$ (10)	$ (35)
Specialty	35	(4)	36
Other	(4)	1	1
Total pretax (favorable) unfavorable development	$ 13	$ (13)	$ 2