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		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Derivative Instruments, Gain (Loss) [Line Items]
Interest on long-term debt	$ (410)	$ (493)	$ (1,258)	$ (1,576)
Gain (loss) on mortgage and automotive loans, net	(2)	0	45	6
Other income, net of losses	80	78	251	214
Gain (Loss) on Interest Rate Derivative Instruments Not Designated as Hedging Instruments	(2)	(5)	(11)	(24)
Gain (Loss) on Equity Forward Contract Not Designated as Hedging Instruments	(4)	(6)	(7)	(6)
Gain (Loss) on Foreign Currency Derivative Instruments Not Designated as Hedging Instruments	0	(100)	(130)	(109)
Gain (Loss) on Derivative Instruments, Net, Pretax	(5)	(88)	(132)	(91)
Interest and Fee Income, Loans and Leases	(1,166)	(1,114)	(3,358)	(3,345)
Interest Gain For Qualifying Accounting Hedges Of Debt	24	27	71	89
Derivative Instruments Not Designated as Hedging Instruments, Gain (Loss), Net	1		1
Gains on amortization of deferred basis adjustments on the hedged items	14	38	59	120
Gain (Loss) from Revaulation of Foreign-Denominated Debt or Receivable	1	102	134	112
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	1	23	16	48
Interest Rate Contract [Member] | Designated as Hedging Instrument [Member] | Gain (Loss) Recognized in Earnings on Derivatives [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Interest on long-term debt	132	(39)	121	102
Interest and Fee Income, Loans and Leases	34	(28)	50	(22)
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 on long-term debt	(135)	49	(128)	(90)
Interest and Fee Income, Loans and Leases	(38)	15	(73)	(14)
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	18	16	50	43
Interest Rate Contract [Member] | Not Designated as Hedging Instrument [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Gain (loss) on mortgage and automotive loans, net	(2)	0	(2)	0
Other income, net of losses	0	(5)	(9)	(24)
Foreign Exchange Contract [Member] | Not Designated as Hedging Instrument [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Interest on long-term debt	(1)	(108)	(139)	(117)
Other income, net of losses	1	8	9	8
Forward Contracts [Member] | Not Designated as Hedging Instrument [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Other income, net of losses	$ (4)	$ (6)	$ (7)	$ (6)