Business Acquisitions (Details textual) - USD ($) $ in Thousands		9 Months Ended
	Nov. 30, 2016	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016
Business Acquisition [Line Items]
Goodwill		$ 930,846			$ 801,406
Prox Dynamics, AS [Member]
Business Acquisition [Line Items]
Business Combination, Consideration Transferred	$ 134,088	$ 134,088
Business Combination, Recognized Identifiable Assets Acquired, Goodwill, and Liabilities Assumed, Net					11,300
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Finite-Lived Intangibles				$ 31,400
Goodwill			$ 99,269	$ 91,900	$ 122,800
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Deferred Tax Assets Noncurrent			$ (7,387)