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		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 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			136	215
Net insurance losses and loss adjustment expenses, prior years			1	1
Total net insurance losses and loss adjustment expenses incurred	$ 74	$ 142	137	216
Net insurance losses and loss adjustment expenses paid or payable, current year			(108)	(178)
Net insurance losses and loss adjustment expenses paid or payable, prior years			(27)	(26)
Total net insurance losses and loss adjustment expenses paid or payable			(135)	(204)
Net reserves for insurance losses and loss adjustment expenses, ending balance	41	46	41	46
Reinsurance recoverable	85	86	85	86
Gross reserves for insurance losses and loss adjustment expenses, ending balance	$ 126	$ 132	$ 126	$ 132