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, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022
Liability for Claims and Claims Adjustment Expense [Line Items]
Commercial	$ (3)	$ (4)	$ (5)	$ (4)
Specialty	3	(1)	22	(1)
Other	0	0	(2)	0
Total pretax (favorable) unfavorable development	$ 0	$ (5)	$ 15	$ (5)