Financial Instruments and Fair Value Measurements (Details Textual)	3 Months Ended			6 Months Ended
	Jun. 30, 2016 USD ($) investment	Mar. 31, 2016 USD ($)	Jun. 30, 2015 USD ($)	Jun. 30, 2016 USD ($) investment	Jun. 30, 2015 USD ($)	Dec. 31, 2015 USD ($)
Business Acquisition [Line Items]
Impairment charges recorded for earnings				$ 0
Unrealized loss position investment | investment	0			0
Net foreign currency exchange gains (losses), includes gains and losses from derivatives instruments	$ (300,000)		$ (300,000)	$ (200,000)	$ 100,000
Contingent Consideration Liability [Member]
Business Acquisition [Line Items]
Contingent consideration liability recorded upon acquisition		$ 21,400,000		21,439,000
Contingent consideration liability	21,800,000			21,800,000
Quoted price in active market (Level 1) [Member] | Convertible Notes due 2017 [Member]
Business Acquisition [Line Items]
Debt instrument, fair value disclosure	182,200,000			182,200,000		$ 551,400,000
Quoted price in active market (Level 1) [Member] | Senior Convertible Notes due 2021 [Member]
Business Acquisition [Line Items]
Debt instrument, fair value disclosure	769,400,000			769,400,000
Foreign Exchange Forward [Member]
Business Acquisition [Line Items]
Notional principal amount	$ 18,500,000			$ 18,500,000		$ 8,500,000