Reserves for Insurance Losses and Loss Adjustment Expenses (Rollforward of Reserves for Insurance Losses and Loss Adjustment Expenses) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Liability for Unpaid Claims and Claims Adjustment Expense [Roll Forward]
Gross reserves for insurance losses and loss adjustment expenses	$ 122	$ 134	$ 140
Reinsurance recoverable	88	96	108
Net reserves for insurance losses and loss adjustment expenses	34	38	32
Net insurance losses and loss adjustment expenses, current year	360	321	291
Net insurance losses and loss adjustment expenses, prior years	3	0	4
Net insurance losses and loss adjustment expenses incurred	363	321	295
Net insurance losses and loss adjustment expenses paid or payable, current year	(328)	(295)	(263)
Net insurance losses and loss adjustment expenses paid or payable, prior years	(30)	(30)	(26)
Total net insurance losses and loss adjustment expenses paid or payable	(358)	(325)	(289)
Net reserves for insurance losses and loss adjustment expenses	39	34	38
Reinsurance recoverable	90	88	96
Gross reserves for insurance losses and loss adjustment expenses	$ 129	$ 122	$ 134