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
	Mar. 31, 2013	Mar. 31, 2012
Derivative Instruments, Gain (Loss) [Line Items]
Interest on long-term debt	$ (701)	$ (880)
Servicing asset valuation and hedge activities, net	(201)	(106)
Gain (loss) on mortgage and automotive loans, net	38	20
Other income, net of losses	157	210
Gain (Loss) on Interest Rate Derivative Instruments Not Designated as Hedging Instruments	(145)	5
Gain (Loss) on Foreign Currency Derivative Instruments Not Designated as Hedging Instruments	67	(34)
Gain (Loss) on Derivative Instruments, Net, Pretax	(75)	(47)
Interest Gain For Qualifying Accounting Hedges Of Debt	33	26
Gains on amortization of deferred basis adjustments on the hedged items	38	60
Gain (Loss) from Revaulation of Foreign-Denominated Debt or Receivable	(65)	31
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	3	(18)
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	(98)	(69)
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	101	51
Interest Rate Contract [Member] | Not Designated as Hedging Instrument [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Servicing asset valuation and hedge activities, net	(112)	(96)
Gain (loss) on mortgage and automotive loans, net	(32)	83
Other income, net of losses	(1)	18
Foreign Exchange Contract [Member] | Not Designated as Hedging Instrument [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Interest on long-term debt	39	(9)
Other income, net of losses	$ 28	$ (25)