Reserves for Insurance Losses and Loss Adjustment Expenses Reserves for Insurance Losses and Loss Adjustment Expenses (Short-duration Insurance Contracts, Reconciliation of Claims Development to Liability) (Details) - USD ($) $ in Millions	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Short-duration Insurance Contracts, Liability for Unpaid Claims and Allocated Claim Adjustment Expense, Net [Abstract]
Short-duration insurance contracts, liability for unpaid claims and allocated claim adjustment expense, net	$ 32	$ 35	$ 30
Reinsurance Recoverable for Paid and Unpaid Claims and Claims Adjustments	88	96	108	$ 108
Short-duration Insurance Contracts, Liability for Unpaid Claims and Claims Adjustment Expense, Accumulated Unallocated Claim Adjustment Expense	2	3	2
Reserves for insurance losses and loss adjustment expenses	$ 122	$ 134	$ 140	$ 149