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		6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012
Derivative Instruments, Gain (Loss) [Line Items]
Interest on long-term debt	$ (703)	$ (837)	$ (1,404)	$ (1,717)
Servicing asset valuation and hedge activities, net	(12)	46	(213)	(60)
Gain (loss) on mortgage and automotive loans, net	(1)	86	37	106
Other income, net of losses	74	144	231	354
Gain (Loss) on Interest Rate Derivative Instruments Not Designated as Hedging Instruments	2	217	(143)	222
Gain (Loss) on Foreign Currency Derivative Instruments Not Designated as Hedging Instruments	(19)	58	48	24
Gain (Loss) on Derivative Instruments, Net, Pretax	(7)	284	(82)	237
Interest Gain For Qualifying Accounting Hedges Of Debt	28	29	61	55
Gains on amortization of deferred basis adjustments on the hedged items	38	59	76	119
Gain (Loss) from Revaulation of Foreign-Denominated Debt or Receivable	18	(56)	(47)	(25)
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	10	9	13	(9)
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	(215)	268	(313)	199
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	225	(259)	326	(208)
Interest Rate Contract [Member] | Not Designated as Hedging Instrument [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Servicing asset valuation and hedge activities, net	0	321	(112)	225
Gain (loss) on mortgage and automotive loans, net	(5)	(59)	(37)	24
Other income, net of losses	7	(45)	6	(27)
Foreign Exchange Contract [Member] | Not Designated as Hedging Instrument [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Interest on long-term debt	(20)	8	19	(1)
Other income, net of losses	$ 1	$ 50	$ 29	$ 25