Derivative instruments (Details 2) (USD $) In Millions, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 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 contracts [Abstract]
Product sales	$ 4,799	$ 4,647	$ 4,595	$ 4,151	$ 4,337	$ 4,201	$ 4,200	$ 3,901	$ 18,192	$ 16,639	$ 15,295
Derivatives in cash flow hedging relationships [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 [Abstract]
Total									85	134	(112)
Derivatives in cash flow hedging relationships [Member] | Foreign currency 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 [Abstract]
Product sales									4	74	(108)
Derivatives in cash flow hedging relationships [Member] | 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 [Abstract]
The amount of gain (loss) recognized in interest and other income, net									82	61	(3)
Derivatives in cash flow hedging relationships [Member] | 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 [Abstract]
The amount of gain (loss) recognized in interest expense, net									$ (1)	$ (1)	$ (1)