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		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Derivative Instruments, Gain (Loss) [Line Items]
Interest on long-term debt	$ (419)	$ (549)	$ (848)	$ (1,083)
Gain (loss) on mortgage and automotive loans, net	1	6	47	6
Other income, net of losses	74	69	171	136
Gain (Loss) on Equity Forward Contract Not Designated as Hedging Instruments	3	0	(3)	0
Gain (Loss) on Interest Rate Derivative Instruments Not Designated as Hedging Instruments	5	(11)	(9)	(19)
Gain (Loss) on Foreign Currency Derivative Instruments Not Designated as Hedging Instruments	2	(4)	(130)	(9)
Gain (Loss) on Derivative Instruments, Net, Pretax	16	(5)	(127)	(3)
Interest and Fee Income, Loans and Leases	1,118	1,124	2,192	2,231
Interest Gain For Qualifying Accounting Hedges Of Debt	24	27	47	62
Gains on amortization of deferred basis adjustments on the hedged items	16	37	44	82
Gain (Loss) from Revaulation of Foreign-Denominated Debt or Receivable	(1)	6	133	10
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	6	10	15	25
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	(97)	107	(11)	141
Interest and Fee Income, Loans and Leases	7	(8)	(16)	(6)
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	94	(107)	7	(139)
Interest and Fee Income, Loans and Leases	2	18	35	29
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	15	14	32	27
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	0	0
Other income, net of losses	3	(11)	(9)	(19)
Foreign Exchange Contract [Member] | Not Designated as Hedging Instrument [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Interest on long-term debt	5	(4)	(138)	(9)
Other income, net of losses	(3)	0	8	0
Forward Contracts [Member] | Not Designated as Hedging Instrument [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Other income, net of losses	$ 3	$ 0	$ (3)	$ 0