Changes in Other Comprehensive Income (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012	Mar. 31, 2013	Dec. 31, 2012	Mar. 31, 2012	Dec. 31, 2011
Changes in Other Comprehensive Income [Abstract]
Other Comprehensive Income (Loss), Unrealized Gain (Loss) on Derivatives Arising During Period, Tax	$ 26	$ 7	$ 71	$ 26
Accumulated Other Comprehensive Income (Loss), Foreign Currency Translation Adjustment, Net of Tax	(29)	(51)	(29)	(51)	(23)	(26)	(32)	(58)
Accumulated Other Comprehensive Income (Loss), Cumulative Changes in Net Gain (Loss) from Cash Flow Hedges, Effect Net of Tax	152	(4)	152	(4)	109	34	(15)	(48)
Accumulated Other Comprehensive Income (Loss), Pension and Other Postretirement Benefit Plans, Net of Tax	(41)	(32)	(41)	(32)	(41)	(41)	(32)	(32)
Accumulated Other Comprehensive Income (Loss), Net of Tax	82	(87)	82	(87)	45	(33)	(79)	(138)
Cumulative Translation Adjustment, Net of Tax, Period Increase (Decrease)	(6)	(19)	(3)	7
Other Comprehensive Income (Loss), Unrealized Gain (Loss) on Derivatives Arising During Period, Before Reclassifications, Net of Tax	47	6	118	28
Other Comprehensive Income (Loss), before Reclassifications, Net of Tax	41	(13)	115	35
Other Comprehensive Income (Loss), Unrealized Gain (Loss) on Derivatives Arising During Period, Reclassified from OCI, Net of Tax	(4)	5	0	16
Other Comprehensive Income (Loss), Reclassifications out of OCI, Net of Tax	(4)	5	0	16
Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Adjustment, Net of Tax	(6)	(19)	(3)	7
Other Comprehensive Income (Loss), Unrealized Gain (Loss) on Derivatives Arising During Period, Net of Tax	43	11	118	44
Other Comprehensive Income (Loss), Net of Tax	37	(8)	115	51
Other Comprehensive Income (Loss), Unrealized Gain (Loss) on Derivatives Arising Reclassed from OCI, Tax	$ 2	$ 4		$ 10