Fair Value (Fair Value Measurement - Reconciliation of Level 3 Assets And Liabilities) (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value, Assets, Beginning balance	$ 29	$ 40
Net realized/unrealized gains (losses) included in earnings, Assets	0	2
Net realized/unrealized gains (losses) included in other comprehensive income, Assets	0	0
Purchases, Assets	3	0
Sales, Assets	2	4
Issuances, Assets	0	0
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Settlements	(2)	(15)
Fair Value, Assets, Ending balance	32	31
Fair Value, Assets Measured on Recurring Basis, Change in Unrealized Gain (Loss)	0	0
Loans Held-for-Sale [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value, Assets, Beginning balance	0
Net realized/unrealized gains (losses) included in earnings, Assets	0
Net realized/unrealized gains (losses) included in other comprehensive income, Assets	0
Purchases, Assets	3
Sales, Assets	(2)
Issuances, Assets	0
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Settlements	0
Fair Value, Assets, Ending balance	1
Fair Value, Assets Measured on Recurring Basis, Change in Unrealized Gain (Loss)	0
Retained Interest [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value, Assets, Beginning balance	29	40
Net realized/unrealized gains (losses) included in earnings, Assets	0	2
Net realized/unrealized gains (losses) included in other comprehensive income, Assets	0	0
Purchases, Assets	0	0
Sales, Assets	4	4
Issuances, Assets	0	0
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Settlements	(2)	(15)
Fair Value, Assets, Ending balance	31	31
Fair Value, Assets Measured on Recurring Basis, Change in Unrealized Gain (Loss)	$ 0	$ 0