Property, plant and equipment (Details) (USD $) In Millions, unless otherwise specified			12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2012 Minimum [Member] Building and Improvements [Member]	Dec. 31, 2012 Minimum [Member] Manufacturing Equipment [Member]	Dec. 31, 2012 Minimum [Member] Laboratory Equipment [Member]	Dec. 31, 2012 Minimum [Member] Other [Member]	Dec. 31, 2012 Maximum [Member] Building and Improvements [Member]	Dec. 31, 2012 Maximum [Member] Manufacturing Equipment [Member]	Dec. 31, 2012 Maximum [Member] Laboratory Equipment [Member]	Dec. 31, 2012 Maximum [Member] Other [Member]
Property, Plant and Equipment [Line Items]
Useful life			10 years	8 years	8 years	3 years	40 years	12 years	12 years	15 years
Property, plant and equipment [Abstract]
Land	$ 412	$ 366
Buildings and improvements	3,510	3,463
Manufacturing equipment	2,007	1,897
Laboratory equipment	1,056	1,016
Other	3,891	3,745
Construction in progress	1,071	744
Property, plant and equipment, gross	11,947	11,231
Less accumulated depreciation and amortization	(6,621)	(5,811)
Property, plant and equipment, net	$ 5,326	$ 5,420