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		6 Months Ended
	Jun. 30, 2024	Jun. 30, 2023	Jun. 30, 2024	Jun. 30, 2023
Liability for Claims and Claims Adjustment Expense [Line Items]
Commercial	$ 6	$ (3)	$ 6	$ (5)
Specialty	(9)	3	(9)	22
Other	0	0	0	(2)
Total pretax (favorable) unfavorable development	$ (3)	$ 0	$ (3)	$ 15