Securitizations And Variable Interest Entities (Schedule Of Variable Interest Entities) (Details) - USD ($) $ in Millions	Jun. 30, 2016	Dec. 31, 2015
Variable Interest Entity [Line Items]
Total consoldiated involvement with VIEs	$ 40,618	$ 44,940
Assets of nonconsolidated variable interest entities	3,727	3,034
Maximum exposure to loss in nonconsolidated VIEs	4,288	3,527
Other assets	6,254	6,321
Consumer Portfolio Segment [Member] | Automobile Loan [Member]
Variable Interest Entity [Line Items]
Assets of nonconsolidated variable interest entities	3,727	3,034
Maximum exposure to loss in nonconsolidated VIEs	3,751	3,034
Variable Interest Entity, Consolidated, Carrying Amount, Assets	24,557	27,967
Variable Interest Entity, Nonconsolidated, Carrying Amount, Assets	24	0
Continuing Involvement with Continued to be Recognized Transferred Financial Assets, Amount Outstanding	10,000	10,600
Commercial Portfolio Segment [Member] | Automobile Loan [Member]
Variable Interest Entity [Line Items]
Variable Interest Entity, Consolidated, Carrying Amount, Assets	15,791	16,763
Commercial Portfolio Segment [Member] | Other Financing Receivables [Member]
Variable Interest Entity [Line Items]
Assets of nonconsolidated variable interest entities	0	0
Maximum exposure to loss in nonconsolidated VIEs	537	493
Variable Interest Entity, Nonconsolidated, Carrying Amount, Assets	246	210
Other assets	254	222
Accrued Liabilities	$ 8	$ 12