Changes in Other Comprehensive Income (Details) (USD $)	3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012	Dec. 31, 2012	Dec. 31, 2011
Changes in Other Comprehensive Income [Abstract]
Other Comprehensive Income (Loss), Unrealized Gain (Loss) on Derivatives Arising During Period, Tax	$ 45,000,000	$ 19,000,000
Accumulated Other Comprehensive Income (Loss), Foreign Currency Translation Adjustment, Net of Tax	(23,000,000)	(33,000,000)	(26,000,000)	(58,000,000)
Accumulated Other Comprehensive Income (Loss), Cumulative Changes in Net Gain (Loss) from Cash Flow Hedges, Effect Net of Tax	109,000,000	(14,000,000)	34,000,000	(48,000,000)
Accumulated Other Comprehensive Income (Loss), Pension and Other Postretirement Benefit Plans, Net of Tax	(41,000,000)	(32,000,000)	(41,000,000)	(32,000,000)
Accumulated Other Comprehensive Income (Loss), Net of Tax	45,000,000	(79,000,000)	(33,000,000)	(138,000,000)
Cumulative Translation Adjustment, Net of Tax, Period Increase (Decrease)	3,000,000	25,000,000
Other Comprehensive Income (Loss), Unrealized Gain (Loss) on Derivatives Arising During Period, Before Reclassifications, Net of Tax	71,000,000	23,000,000
Other Comprehensive Income (Loss), before Reclassifications, Net of Tax	74,000,000	48,000,000
Other Comprehensive Income (Loss), Unrealized Gain (Loss) on Derivatives Arising During Period, Reclassified from OCI, Net of Tax	4,000,000	11,000,000
Other Comprehensive Income (Loss), Reclassifications out of OCI, Net of Tax	4,000,000	11,000,000
Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Adjustment, Net of Tax	3,000,000	25,000,000
Other Comprehensive Income (Loss), Unrealized Gain (Loss) on Derivatives Arising During Period, Net of Tax	75,000,000	34,000,000
Other Comprehensive Income (Loss), Net of Tax	78,000,000	59,000,000
Segment Reporting Information, Revenue for Reportable Segment	1,749,000,000	1,826,000,000
Other Comprehensive Income (Loss), Unrealized Gain (Loss) on Derivatives Arising Reclassed from OCI, Tax	$ 2,000,000	$ 6,000,000