Accumulated Other Comprehensive Loss (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012	Mar. 31, 2013 Accumulated Currency Translation Adjustment	Mar. 31, 2012 Accumulated Currency Translation Adjustment	Mar. 31, 2013 Accumulated Deferred Gain/(Loss) on Hedging Activities	Mar. 31, 2012 Accumulated Deferred Gain/(Loss) on Hedging Activities	Mar. 31, 2013 Accumulated Pension Liability Adjustment	Mar. 31, 2012 Accumulated Pension Liability Adjustment	Dec. 31, 2011 Accumulated Pension Liability Adjustment	Mar. 31, 2013 Accumulated Unrealized Loss on Investment	Dec. 31, 2012 Accumulated Unrealized Loss on Investment	Mar. 31, 2012 Accumulated Unrealized Loss on Investment	Dec. 31, 2011 Accumulated Unrealized Loss on Investment
Accumulated other comprehensive loss
Balance at the beginning of the period	$ (475)	$ (413)	$ (335)	$ (306)	$ (17)	$ (35)	$ (121)	$ (70)	$ (70)	$ (2)	$ (2)	$ (2)	$ (2)
Losses on cash flow hedges, net of income tax effect of $4 and $16 for the three months ended March 31, 2013 and 2012, respectively	(9)	(29)			(9)	(29)
Amount of (gains) losses on cash flow hedges reclassified to earnings, net of income tax effect of $6 and $2 at March 31, 2013 and March 31, 2012, respectively	(12)	5			(12)	5
Losses related to pension and other postretirement obligations reclassified to earnings, net of income tax	1						1
Currency translation adjustment	(22)	36	(22)	36
Balance at end of the period	(517)	(401)	(357)	(270)	(38)	(59)	(120)	(70)	(70)	(2)	(2)	(2)	(2)
Income tax effect of accumulated other comprehensive gain (loss)
Losses on cash flow hedges, income tax effect	(4)	(16)			(4)	(16)
Amount of (gains) losses on cash flow hedges reclassified to earnings, income tax effect	$ (6)	$ 2			$ (6)	$ 2