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, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Derivative Instruments, Gain (Loss) [Line Items]
Location of (Loss) Gain Recognized in Income on Derivatives			$ (2,092)	$ 2,842
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	$ 334	4	767
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	$ (236)	$ 350	$ (1,891)	$ 1,950