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		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Derivative Instruments, Gain (Loss) [Line Items]
Location of (Loss) Gain Recognized in Income on Derivatives			$ (1,823)	$ 2,161
Foreign exchange contract | Cost of Revenues | Not Designated as Hedging Instrument
Derivative Instruments, Gain (Loss) [Line Items]
Location of (Loss) Gain Recognized in Income on Derivatives	$ 0	$ (798)	4	434
Interest swap contract | Interest and Other Expense | Not Designated as Hedging Instrument
Derivative Instruments, Gain (Loss) [Line Items]
Location of (Loss) Gain Recognized in Income on Derivatives	$ (1,004)	$ 438	$ (1,656)	$ 1,600