Securitizations And Variable Interest Entities (Schedule Of Variable Interest Entities) (Details) - USD ($) $ in Millions	Sep. 30, 2015	Dec. 31, 2014
Variable Interest Entity [Line Items]
Assets of nonconsolidated variable interest entities	$ 2,870	$ 2,801
Maximum exposure to loss in nonconsolidated VIEs	3,315	3,163
Total consoldiated involvement with VIEs	44,744	50,311
Other Assets	6,024	7,302
Consumer Portfolio Segment [Member] | Automobile Loan [Member]
Variable Interest Entity [Line Items]
Variable Interest Entity, Consolidated, Carrying Amount, Assets	29,429	31,994
Variable Interest Entity, Nonconsolidated, Carrying Amount, Assets	0	0
Assets of nonconsolidated variable interest entities	2,870	2,801
Maximum exposure to loss in nonconsolidated VIEs	2,870	2,801
Continuing Involvement with Continued to be Recognized Transferred Financial Assets, Amount Outstanding	10,200	12,700
Commercial Portfolio Segment [Member] | Automobile Loan [Member]
Variable Interest Entity [Line Items]
Variable Interest Entity, Consolidated, Carrying Amount, Assets	15,118	18,171
Commercial Portfolio Segment [Member] | Other Financing Receivables [Member]
Variable Interest Entity [Line Items]
Variable Interest Entity, Nonconsolidated, Carrying Amount, Assets	197	146
Assets of nonconsolidated variable interest entities	0	0
Maximum exposure to loss in nonconsolidated VIEs	445	362
Other Assets	211	164
Accrued Liabilities	$ 14	$ 18