Derivatives and Hedge Accounting- Location of Gain or Loss Recognized (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Derivative Instruments, Gain (Loss) [Line Items]
Cost of revenues	$ 158,401	$ 162,446	$ 321,057	$ 319,686
General and administrative expenses	28,750	31,228	57,691	63,759
Selling & marketing expenses	13,051	17,647	27,507	35,694
Depreciation & amortization expense	12,405	12,752	24,855	26,419
Foreign exchange gain, net	1,359	1,202	2,736	2,462
(Loss)/Gain on foreign currency exchange contracts | Derivatives Designated as Hedging Instruments | Derivatives in cash flow hedging relationships | Foreign currency exchange contracts
Derivative Instruments, Gain (Loss) [Line Items]
Cost of revenues	(851)	719	(39)	1,250
General and administrative expenses	(187)	106	(114)	186
Selling & marketing expenses	(9)	12	(5)	19
Depreciation & amortization expense	(80)	47	(40)	100
Reclassification from AOCI, before tax	(1,127)	884	(198)	1,555
(Loss)/Gain on foreign currency exchange contracts | Derivatives not designated as hedging instruments | Foreign currency exchange contracts
Derivative Instruments, Gain (Loss) [Line Items]
Foreign exchange gain, net	$ 3,204	$ 2,923	$ (1,011)	$ 4,319