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
	Mar. 31, 2019	Mar. 31, 2018
Derivative Instruments, Gain (Loss) [Line Items]
Amount of Gain (Loss) Recognized in Income on Derivatives	$ (737)	$ 2,489
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	4	1,232
Interest swap contract | Interest and Other Expense | Not Designated as Hedging Instrument
Derivative Instruments, Gain (Loss) [Line Items]
Amount of Gain (Loss) Recognized in Income on Derivatives	$ (652)	$ 1,162