Derivative Instruments And Hedging Activities (Statement Of Gains and Losses on Derivative Instruments Reported in Statement of Comprehensive Income) (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Derivative Instruments, Gain (Loss) [Line Items]
Interest on long-term debt	$ (442)	$ (429)
Gain (loss) on mortgage and automotive loans, net	1	46
Other income, net of losses	82	97
Gain (Loss) on Interest Rate Derivative Instruments Not Designated as Hedging Instruments	2	(14)
Gain (Loss) on Equity Forward Contract Not Designated as Hedging Instruments	(1)	(6)
Gain (Loss) on Foreign Currency Derivative Instruments Not Designated as Hedging Instruments	(5)	(132)
Gain (Loss) on Derivative Instruments, Net, Pretax	(9)	(143)
Interest and Fee Income, Loans and Leases	(1,235)	(1,074)
Interest Gain For Qualifying Accounting Hedges Of Debt	16	23
Derivative Instruments Not Designated as Hedging Instruments, Gain (Loss), Net	5
Gains on amortization of deferred basis adjustments on the hedged items	18	28
Gain (Loss) from Revaulation of Foreign-Denominated Debt or Receivable	4	134
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	(5)	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	191	86
Interest and Fee Income, Loans and Leases	(28)	(23)
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	(196)	(87)
Interest and Fee Income, Loans and Leases	28	33
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	7	17
Interest Rate Contract [Member] | Not Designated as Hedging Instrument [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Gain (loss) on mortgage and automotive loans, net	0	(2)
Other income, net of losses	2	(12)
Foreign Exchange Contract [Member] | Not Designated as Hedging Instrument [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Interest on long-term debt	(1)	(143)
Other income, net of losses	(4)	11
Forward Contracts [Member] | Not Designated as Hedging Instrument [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Other income, net of losses	(1)	$ (6)
Secured Debt [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Interest Gain For Qualifying Accounting Hedges Of Debt	$ 1