Fair value measurements (Details Textual) - USD ($)		6 Months Ended
	Oct. 14, 2015	Jun. 30, 2016	Dec. 31, 2015	Oct. 31, 2015	Mar. 31, 2011
Business Acquisition [Line Items]
Length of time hedged in foreign currency contracts (or less)		3 years
Aggregate fair value of long-term debt, including current portion		$ 36,800,000,000	$ 33,100,000,000
Carrying value of long-term debt, including current portion		$ 33,222,000,000	$ 31,429,000,000
Dezima [Member]
Business Acquisition [Line Items]
Maximum additional consideration due contingent on milestones	$ 1,250,000,000.00			$ 1,250,000,000.00
Estimated fair values of contingent consideration obligations	$ 110,000,000
BioVex [Member]
Business Acquisition [Line Items]
Maximum additional consideration due contingent on milestones					$ 325,000,000
Other Government-related and Corporate Debt Securities [Member]
Business Acquisition [Line Items]
Investment maturity period		5 years