Derivative instruments (Details 1) (Derivatives in cash flow hedging relationships [Member], USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Location in the Consolidated Statements of Income and the effective portion of gain/(loss) reclassified from Accumulated Other Comprehensive Income into earnings for our derivative instruments designated as cash flow hedges contracts
Total	$ (112)	$ 46	$ (8)
Foreign currency contracts [Member] | Product sales [Member]
Location in the Consolidated Statements of Income and the effective portion of gain/(loss) reclassified from Accumulated Other Comprehensive Income into earnings for our derivative instruments designated as cash flow hedges contracts
The amount of gain (loss) recognized in product sales	(108)	47	(7)
Cross currency swap contracts [Member]
Location in the Consolidated Statements of Income and the effective portion of gain/(loss) reclassified from Accumulated Other Comprehensive Income into earnings for our derivative instruments designated as cash flow hedges contracts
The amount of gain (loss) recognized in interest and other income, net	(3)	0	0
Forward interest rate contracts [Member]
Location in the Consolidated Statements of Income and the effective portion of gain/(loss) reclassified from Accumulated Other Comprehensive Income into earnings for our derivative instruments designated as cash flow hedges contracts
The amount of gain (loss) recognized in interest expense, net	$ (1)	$ (1)	$ (1)