Income Effect of Derivative Financial Instruments (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Derivative [Line Items]
Derivative, Gain (Loss) on Derivative, Net	$ (81)	$ 32	$ 124	$ 78
Designated as Hedging Instrument [Member] | Fair Value Hedging [Member] | Interest Rate Contract [Member]
Derivative [Line Items]
Net interest settlements and accruals excluded from the assessment of hedge effectiveness	89	72	177	141
Gain (Loss) on Interest Rate Fair Value Hedge Ineffectiveness	(10)	5	(4)	10
Change in Unrealized Gain (Loss) on Fair Value Hedging Instruments	(249)	162	(28)	267
Change in Unrealized Gain (Loss) on Hedged Item in Fair Value Hedge	239	(157)	24	(257)
Not Designated as Hedging Instrument [Member] | Interest Rate Contract [Member]
Derivative [Line Items]
Derivative, Gain (Loss) on Derivative, Net	(18)	(9)	(61)	(27)
Not Designated as Hedging Instrument [Member] | Foreign Exchange Contract [Member]
Derivative [Line Items]
Derivative, Gain (Loss) on Derivative, Net	(65)	(25)	0	(30)
Not Designated as Hedging Instrument [Member] | Cross Currency Interest Rate Contract [Member]
Derivative [Line Items]
Derivative, Gain (Loss) on Derivative, Net	$ (77)	$ (11)	$ 12	$ (16)