Securitizations And Variable Interest Entities (Schedule Of Variable Interest Entities) (Details) - USD ($) $ in Millions	Mar. 31, 2016	Dec. 31, 2015
Variable Interest Entity [Line Items]
Total consoldiated involvement with VIEs	$ 43,474	$ 44,940
Assets of nonconsolidated variable interest entities	3,647	3,034
Maximum exposure to loss in nonconsolidated VIEs	4,195	3,527
Other assets	6,582	6,321
Consumer Portfolio Segment [Member] | Automobile Loan [Member]
Variable Interest Entity [Line Items]
Assets of nonconsolidated variable interest entities	3,647	3,034
Maximum exposure to loss in nonconsolidated VIEs	3,672	3,034
Variable Interest Entity, Nonconsolidated, Carrying Amount, Assets	25	0
Variable Interest Entity, Consolidated, Carrying Amount, Assets	27,408	27,967
Continuing Involvement with Continued to be Recognized Transferred Financial Assets, Amount Outstanding	10,200	10,600
Commercial Portfolio Segment [Member] | Automobile Loan [Member]
Variable Interest Entity [Line Items]
Variable Interest Entity, Consolidated, Carrying Amount, Assets	15,817	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	523	493
Variable Interest Entity, Nonconsolidated, Carrying Amount, Assets	224	210
Other assets	234	222
Accrued Liabilities	$ 10	$ 12