Reserves for Insurance Losses and Loss Adjustment Expenses (Rollforward of Reserves for Insurance Losses and Loss Adjustment Expenses) (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Liability for Unpaid Claims and Claims Adjustment Expense [Roll Forward]
Gross reserves for insurance losses and loss adjustment expenses, beginning balance	$ 122	$ 129
Reinsurance recoverable	81	90
Net reserves for insurance losses and loss adjustment expenses, beginning balance	41	39
Net insurance losses and loss adjustment expenses, current year	61	64
Net insurance losses and loss adjustment expenses, prior years	(3)	(1)
Total net insurance losses and loss adjustment expenses incurred	58	63
Net insurance losses and loss adjustment expenses paid or payable, current year	(36)	(36)
Net insurance losses and loss adjustment expenses paid or payable, prior years	(20)	(23)
Total net insurance losses and loss adjustment expenses paid or payable	(56)	(59)
Net reserves for insurance losses and loss adjustment expenses, ending balance	43	43
Reinsurance recoverable	80	89
Gross reserves for insurance losses and loss adjustment expenses, ending balance	$ 123	$ 132