Claim and Claim Adjustment Expense Reserves (International - Net prior year claim and allocated claim adjustment expense reserve development) (Details) - International - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Liability for Claims and Claims Adjustment Expense [Line Items]
Commercial	$ 0	$ (2)
Specialty	0	19
Other	0	(2)
Total pretax (favorable) unfavorable development	$ 0	$ 15