Changes in Other Comprehensive Income (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015	Dec. 31, 2015	Dec. 31, 2014
Changes in Other Comprehensive Income [Abstract]
Accumulated Other Comprehensive Income (Loss), Foreign Currency Translation Adjustment, Net of Tax	$ (38)	$ (73)	$ (54)	$ (38)
Accumulated Other Comprehensive Income (Loss), Cumulative Changes in Net Gain (Loss) from Cash Flow Hedges, Effect Net of Tax	83	247	152	219
Accumulated Other Comprehensive Income (Loss), Pension and Other Postretirement Benefit Plans, Net of Tax	(10)	(32)	(10)	(37)
Accumulated Other Comprehensive Income (Loss), Net of Tax	35	142	$ 88	$ 144
Cumulative Translation Adjustment, Net of Tax, Period Increase (Decrease)	16	(35)
Other Comprehensive Income (Loss), Unrealized Gain (Loss) on Derivatives Arising During Period, Before Reclassifications, Net of Tax	(38)	59
Other Comprehensive (Income) Loss, Pension and Other Postretirement Benefit Plans, Adjustment, before Reclassification Adjustments, Net of Tax	(2)	(3)
Other Comprehensive Income (Loss), before Reclassifications, Net of Tax	(24)	21
Other Comprehensive Income (Loss), Unrealized Gain (Loss) on Derivatives Arising During Period, Reclassified from OCI, Net of Tax	(31)	(31)
Other Comprehensive (Income) Loss, Reclassification Adjustment from AOCI, Pension and Other Postretirement Benefit Plans, Net of Tax	2	8
Other Comprehensive Income (Loss), Reclassifications out of OCI, Net of Tax	(29)	(23)
Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Adjustment, Net of Tax	16	(35)
Other Comprehensive Income (Loss), Unrealized Gain (Loss) on Derivatives Arising During Period, Net of Tax	(69)	28
Net change in certain retirement plans, net of tax	0	5
Other Comprehensive Income (Loss), Net of Tax	(53)	(2)
Other Comprehensive Income (Loss), Unrealized Gain (Loss) on Derivatives Arising During Period, Tax	21	(34)
Other Comprehensive Income (Loss), Unrealized Gain (Loss) on Derivatives Arising Reclassed from OCI, Tax	$ 17	18
Other Comprehensive Income (Loss) for defined benefit and pension items, reclassified out of OCI, tax impact		$ 4