Derivative Contracts - Effect of Derivative Instruments on Consolidated Statements of Operations for Derivatives not Designated as Hedging Instruments (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Derivative Instruments, Gain (Loss) [Line Items]
Amount of Gain (Loss) Recognized in Income on Derivatives			$ 979	$ (208)
Foreign exchange contract | Cost of Revenues | Not Designated as Hedging Instrument
Derivative Instruments, Gain (Loss) [Line Items]
Amount of Gain (Loss) Recognized in Income on Derivatives	$ (322)	$ (869)	1,438	(205)
Interest swap contract | Interest Income (Expense) | Not Designated as Hedging Instrument
Derivative Instruments, Gain (Loss) [Line Items]
Amount of Gain (Loss) Recognized in Income on Derivatives	$ 38	$ 0	$ (485)	$ 0