Changes in Other Comprehensive Income (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2014	Mar. 31, 2013	Dec. 31, 2013	Dec. 31, 2012
Changes in Other Comprehensive Income [Abstract]
Accumulated Other Comprehensive Income (Loss), Foreign Currency Translation Adjustment, Net of Tax	$ (22)	$ (23)	$ (16)	$ (26)
Accumulated Other Comprehensive Income (Loss), Cumulative Changes in Net Gain (Loss) from Cash Flow Hedges, Effect Net of Tax	114	109	141	34
Accumulated Other Comprehensive Income (Loss), Pension and Other Postretirement Benefit Plans, Net of Tax	(20)	(41)	(19)	(41)
Accumulated Other Comprehensive Income (Loss), Net of Tax	72	45	106	(33)
Cumulative Translation Adjustment, Net of Tax, Period Increase (Decrease)	(6)	3
Other Comprehensive Income (Loss), Unrealized Gain (Loss) on Derivatives Arising During Period, Before Reclassifications, Net of Tax	(14)	71
Other Comprehensive (Income) Loss, Pension and Other Postretirement Benefit Plans, Adjustment, before Reclassification Adjustments, Net of Tax	(1)	0
Other Comprehensive Income (Loss), before Reclassifications, Net of Tax	(21)	74
Other Comprehensive Income (Loss), Unrealized Gain (Loss) on Derivatives Arising During Period, Reclassified from OCI, Net of Tax	(13)	4
Other Comprehensive Income (Loss), Reclassifications out of OCI, Net of Tax	(13)	4
Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Adjustment, Net of Tax	(6)	3
Other Comprehensive Income (Loss), Unrealized Gain (Loss) on Derivatives Arising During Period, Net of Tax	(27)	75
Net change in certain retirement plans	(1)	0
Other Comprehensive Income (Loss), Net of Tax	(34)	78
Other Comprehensive Income (Loss), Unrealized Gain (Loss) on Derivatives Arising During Period, Tax	7	43
Other Comprehensive Income (Loss), Unrealized Gain (Loss) on Derivatives Arising Reclassed from OCI, Tax	$ 8	$ 2