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, 2015	Mar. 31, 2014
Derivative Instruments, Gain (Loss) [Line Items]
Interest and Fee Income, Loans and Leases	$ 1,074	$ 1,107
Interest on long-term debt	(429)	(534)
Gain (loss) on mortgage and automotive loans, net	46	0
Other income, net of losses	97	67
Gain (Loss) on Equity Forward Contract Not Designated as Hedging Instruments	(6)	0
Gain (Loss) on Interest Rate Derivative Instruments Not Designated as Hedging Instruments	(14)	(8)
Gain (Loss) on Foreign Currency Derivative Instruments Not Designated as Hedging Instruments	(132)	(5)
Gain (Loss) on Derivative Instruments, Net, Pretax	(143)	2
Interest Gain For Qualifying Accounting Hedges Of Debt	23	35
Gains on amortization of deferred basis adjustments on the hedged items	28	45
Gain (Loss) from Revaulation of Foreign-Denominated Debt or Receivable	134	4
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	9	15
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	(23)	2
Interest on long-term debt	86	34
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	33	11
Interest on long-term debt	(87)	(32)
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	17	13
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
Other income, net of losses	(12)	(8)
Foreign Exchange Contract [Member] | Not Designated as Hedging Instrument [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Interest on long-term debt	(143)	(5)
Other income, net of losses	11	0
Forward Contracts [Member] | Not Designated as Hedging Instrument [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Other income, net of losses	$ (6)	$ 0