Accumulated Other Comprehensive Income (Loss) (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended			12 Months Ended							12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2012	Dec. 31, 2012 Net Effect of Exchange Rate Fluctuations	Dec. 31, 2011 Net Effect of Exchange Rate Fluctuations	Dec. 31, 2010 Net Effect of Exchange Rate Fluctuations	Dec. 31, 2012 Deferred Tax Effect for Translation	Dec. 31, 2011 Deferred Tax Effect for Translation	Dec. 31, 2010 Deferred Tax Effect for Translation	Dec. 31, 2009 Deferred Tax Effect for Translation	Dec. 31, 2012 Change in Certain Derivative Instruments	Dec. 31, 2011 Change in Certain Derivative Instruments	Dec. 31, 2010 Change in Certain Derivative Instruments	Dec. 31, 2012 Employee Benefit Plans	Dec. 31, 2011 Employee Benefit Plans	Dec. 31, 2010 Employee Benefit Plans	Dec. 31, 2012 Accumulated Other Comprehensive Income (Loss)	Dec. 31, 2011 Accumulated Other Comprehensive Income (Loss)	Dec. 31, 2010 Accumulated Other Comprehensive Income (Loss)
Increase (Decrease) Accumulated Other Comprehensive Income (Loss), Net of Tax
Balance at beginning of the period	$ (897)		$ (1,506)	$ 476	$ 672	$ 290	$ 13	$ 13	$ 13	$ 13	$ (19)	$ (16)	$ (14)	$ (1,791)	$ (1,566)	$ (1,607)	$ (1,321)	$ (897)	$ (1,318)
Change				(34)	(187)	382					5	(3)	(2)	(200)	(218)	60	(229)	(408)	440
Translation effect														(9)	1	(1)	(9)	1	(1)
Tax effect														53	(8)	(4)	53	(8)	(4)
Acquisition of noncontrolling interest	(107)	(18)			(9)													(9)
Intraperiod tax allocation		8														(14)			(14)
Balance at end of the period	$ (1,321)	$ (897)	$ (1,506)	$ 442	$ 476	$ 672	$ 13	$ 13	$ 13	$ 13	$ (14)	$ (19)	$ (16)	$ (1,947)	$ (1,791)	$ (1,566)	$ (1,506)	$ (1,321)	$ (897)