Derivative Instruments And Hedging Activities (Statement Of Gains and Losses on Derivative Instruments Reported in Statement of Comprehensive Income) (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Derivative Instruments, Gain (Loss) [Line Items]
Interest and Fee Income, Loans and Leases	$ (1,265)	$ (1,118)	$ (2,500)	$ (2,192)
Interest on long-term debt	(436)	(419)	(878)	(848)
Gain (loss) on mortgage and automotive loans, net	3	1	4	47
Other income, net of losses	96	84	191	191
Gain (Loss) on Interest Rate Derivative Instruments Not Designated as Hedging Instruments	1	5	3	(9)
Gain (Loss) on Foreign Currency Derivative Instruments Not Designated as Hedging Instruments	0	2	(5)	(130)
Gain (Loss) on Equity Forward Contract Not Designated as Hedging Instruments	(1)	3	(2)	(3)
Gain (Loss) on Derivative Instruments, Net, Pretax	0	16	(9)	(127)
Interest Gain For Qualifying Accounting Hedges Of Debt	11	24	27	47
Derivative Instruments Not Designated as Hedging Instruments, Gain (Loss), Net	4	1	9	1
Gains on amortization of deferred basis adjustments on the hedged items	21	16	39	44
Gain (Loss) from Revaulation of Foreign-Denominated Debt or Receivable	(1)	1	3	133
Designated as Hedging Instrument [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Derivative Instruments, Gain (Loss) Recognized in Income, Ineffective Portion and Amount Excluded from Effectiveness Testing, Net	0	6	(5)	15
Interest Rate Contract [Member] | Designated as Hedging Instrument [Member] | Gain (Loss) Recognized in Earnings on Derivatives [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Interest and Fee Income, Loans and Leases	(6)	7	34	16
Interest on long-term debt	51	(97)	242	(11)
Interest Rate Contract [Member] | Designated as Hedging Instrument [Member] | Gain (Loss) Recognized in Earnings on Hedged Item [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Interest and Fee Income, Loans and Leases	5	2	(33)	(35)
Interest on long-term debt	(50)	94	(246)	7
Interest Rate Contract [Member] | Designated as Hedging Instrument [Member] | Gain (loss) Excluded from Earnings on Derivatives [Domain]
Derivative Instruments, Gain (Loss) [Line Items]
Interest and Fee Income, Loans and Leases	(5)	(15)	(12)	(32)
Interest Rate Contract [Member] | Not Designated as Hedging Instrument [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Gain (loss) on mortgage and automotive loans, net	0	2	0	0
Other income, net of losses	1	3	3	(9)
Foreign Exchange Contract [Member] | Not Designated as Hedging Instrument [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Interest on long-term debt	(1)	5	(2)	(138)
Other income, net of losses	1	(3)	(3)	8
Forward Contracts [Member] | Not Designated as Hedging Instrument [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Other income, net of losses	(1)	$ 3	(2)	$ (3)
Secured Debt [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Interest Gain For Qualifying Accounting Hedges Of Debt	$ 2		$ 3