Derivative Instruments and Hedging Activities Derivative Instruments and Hedging Activities (Ineffective Portion of Cash Flow Hedges) (Details) - Cash Flow Hedging - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Derivative Instruments, Gain (Loss) [Line Items]
Derivative Instruments, Gain (Loss) Reclassified from Accumulated OCI into Income, Effective Portion, Net	$ (45)	$ (77)	$ (125)
Accumulated Other Comprehensive Income Loss Before Tax Expected Increase Decrease Next Twelve Months	90
Interest Rate Contract
Derivative Instruments, Gain (Loss) [Line Items]
Derivative Instruments, Gain (Loss) Reclassified from Accumulated OCI into Income, Effective Portion, Net	(101)	(116)	(144)
Gain (Losses) Recognized in Earnings, Ineffective Portion	(1)	(6)	(4)
Foreign Exchange Contract [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Derivative Instruments, Gain (Loss) Reclassified from Accumulated OCI into Income, Effective Portion, Net	(8)	32	14
Cross Currency Interest Rate Contract [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Derivative Instruments, Gain (Loss) Reclassified from Accumulated OCI into Income, Effective Portion, Net	$ 8	$ (24)	$ (23)