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, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011
Derivative Instruments, Gain (Loss) [Line Items]
Interest on long-term debt	$ 1,041	$ 1,293	$ 3,286	$ 4,030
Servicing asset valuation and hedge activities, net	134	(471)	70	(663)
Gain (loss) on mortgage and automotive loans, net	141	95	401	301
Other gain (loss) on investments, net	(19)	75	137	251
Other income, net of losses	225	130	728	573
Other operating expenses	619	754	3,268	2,392
Gain (Loss) on Interest Rate Derivative Instruments Not Designated as Hedging Instruments	408	275	616	(57)
Gain (Loss) on Foreign Currency Derivative Instruments Not Designated as Hedging Instruments	(90)	146	(75)	76
Gain (Loss) on Derivative Instruments, Net, Pretax	302	450	517	54
Interest Gain For Qualifying Accounting Hedges Of Debt	29	64	88	231
Gains on amortization of deferred basis adjustments on the hedged items	57	49	181	162
Gain (Loss) from Revaulation of Foreign-Denominated Debt or Receivable	92	(157)	66	(105)
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	(16)	29	(24)	35
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	17	706	214	821
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	(33)	(677)	(238)	(786)
Interest Rate Contract [Member] | Not Designated as Hedging Instrument [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Interest on long-term debt	0	0	(3)	(1)
Servicing asset valuation and hedge activities, net	387	741	725	664
Gain (loss) on mortgage and automotive loans, net	28	(425)	(68)	(646)
Other gain (loss) on investments, net	0	0	0	0
Other income, net of losses	(7)	(41)	(38)	(74)
Other operating expenses	0	0	0	0
Foreign Exchange Contract [Member] | Not Designated as Hedging Instrument [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Interest on long-term debt	(37)	41	(49)	103
Other income, net of losses	(53)	111	(28)	(11)
Other operating expenses	$ 0	$ (6)	$ 2	$ (16)