Derivative instruments (Locations and Gain (Loss) for Derivatives Not Designated as Hedging Instruments) (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Foreign currency contracts [Member] | Interest and other income, net [Member]
Location in the Condensed Consolidated Statements of Income and the amount of gain (loss) recognized in earnings for our derivative instruments not designated as hedging instruments
Amount of gain (loss) recognized in interest and other income, net	$ (24)	$ 20	$ (34)	$ (9)