Derivative instruments (Details 2) (Foreign currency contracts [Member], Interest and other income, net [Member], USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2012	Mar. 31, 2011
Foreign currency contracts [Member] | Interest and other income, net [Member]
Location in the Consolidated Statements of Income and the amount of gain (loss) recognized in earnings for our derivative instruments not designated as hedging instruments
The amount of gain (loss) recognized in interest and other income, net	$ (10)	$ (51)