Derivative Instruments And Hedging Activities (Statement Of Gains and Losses on Derivative Instruments Reported in Statement of Comprehensive Income) (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Derivative Instruments, Gain (Loss) [Line Items]
Interest and Fee Income, Loans and Leases	$ 1,119	$ 1,141	$ 3,393	$ 3,374
Interest on long-term debt	(609)	(851)	(2,013)	(2,568)
Servicing asset valuation and hedge activities, net	0	134	(213)	74
Gain (loss) on mortgage and automotive loans, net	15	142	52	248
Other income, net of losses	93	169	324	523
Gain (Loss) on Interest Rate Derivative Instruments Not Designated as Hedging Instruments	20	411	(123)	633
Gain (Loss) on Foreign Currency Derivative Instruments Not Designated as Hedging Instruments	48	(90)	96	(66)
Gain (Loss) on Derivative Instruments, Net, Pretax	64	305	(18)	542
Interest Gain For Qualifying Accounting Hedges Of Debt	33	29	94	85
Gains on amortization of deferred basis adjustments on the hedged items	112	57	188	176
Gain (Loss) from Revaulation of Foreign-Denominated Debt or Receivable	(47)	92	(94)	67
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	(4)	(16)	9	(25)
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	3	0	3	0
Interest on long-term debt	11	17	(302)	216
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	(3)	0	(3)	0
Interest on long-term debt	(15)	(33)	311	(241)
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	(1)		(1)
Interest Rate Contract [Member] | Not Designated as Hedging Instrument [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Servicing asset valuation and hedge activities, net	0	387	(112)	612
Gain (loss) on mortgage and automotive loans, net	0	28	(37)	52
Other income, net of losses	20	(4)	26	(31)
Foreign Exchange Contract [Member] | Not Designated as Hedging Instrument [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Interest on long-term debt	52	(38)	71	(39)
Other income, net of losses	$ (4)	$ (52)	$ 25	$ (27)