Reserves for Insurance Losses and Loss Adjustment Expenses (Short-duration Insurance Contracts, Reconciliation of Claims Development to Liability) (Details) - USD ($) $ in Millions	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Reserves for Insurance Losses and Loss Adjustment Expenses (Short-duration Insurance Contracts, Reconciliation of Claims Development to Liability) [Abstract]
Reserves for insurance losses and loss adjustment expenses, net of reinsurance	$ 35	$ 30	$ 38
Reinsurance recoverable on unpaid claims	96	108	108	$ 120
Unallocated loss adjustment expenses	3	2	3
Reserves for insurance losses and loss adjustment expenses	$ 134	$ 140	$ 149	$ 169