Derivative instruments (Details 2) (USD $) In Millions, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011
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
Total	$ 96	$ (42)	$ 120	$ (83)
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
The amount of gain (loss) recognized in product sales	38	(41)	67	(82)
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
The amount of gain (loss) recognized in interest and other income, net	58	0	54	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
The amount of gain (loss) recognized in interest expense, net	$ 0	$ (1)	$ (1)	$ (1)