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		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Liability for Unpaid Claims and Claims Adjustment Expense [Roll Forward]
Gross reserves for insurance losses and loss adjustment expenses, beginning balance			$ 129	$ 122
Reinsurance recoverable			90	88
Net reserves for insurance losses and loss adjustment expenses, beginning balance			39	34
Net insurance losses and loss adjustment expenses, current year			207	298
Net insurance losses and loss adjustment expenses, prior years			(1)	3
Total net insurance losses and loss adjustment expenses incurred	$ 69	$ 85	206	301
Net insurance losses and loss adjustment expenses paid or payable, current year			(174)	(271)
Net insurance losses and loss adjustment expenses paid or payable, prior years			(29)	(27)
Total net insurance losses and loss adjustment expenses paid or payable			(203)	(298)
Net reserves for insurance losses and loss adjustment expenses, ending balance	42	37	42	37
Reinsurance recoverable	83	88	83	88
Gross reserves for insurance losses and loss adjustment expenses, ending balance	$ 125	$ 125	$ 125	$ 125