CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME - USD ($) shares in Thousands, $ in Thousands		3 Months Ended		6 Months Ended
		Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Net revenues	[1]	$ 249,699	$ 226,811	$ 495,044	$ 452,680
Cost of revenues		165,058	145,053	319,149	288,213
Gross profit		84,641	81,758	175,895	164,467
Selling, general and administrative expenses		27,646	28,659	54,632	58,913
Income from operations		56,995	53,099	121,263	105,554
Interest expense		(2,193)	(3,216)	(4,626)	(6,592)
Other income		1,470	462	2,031	958
Non-Service components of post retirement benefit cost		(288)	(338)	(590)	(662)
Other expense, net (See note 23)		(1,011)	(3,092)	(3,185)	(6,296)
Income before provision for income taxes		55,984	50,007	118,078	99,258
Income tax expense		14,836	13,355	31,291	24,226
Net income		41,148	36,652	86,787	75,032
Other comprehensive (loss) income
Foreign currency translation adjustments		(12,614)	937	(15,071)	7,112
Gains/(losses) on derivatives:
Gain/(loss) arising during period on cash flow hedges		975	(672)	3,885	291
Unrealized gains on available-for-sale debt securities:
Unrealized holding gains arising during period		426	198	699	241
Reclassification adjustment for gains included in net income		(207)	(89)	(156)	(81)
Unrealized gains on securities, Total		219	109	543	160
Defined benefit pension plans:
Prior service cost arising during period				(457)
Net profit arising during period				18	6
Amortization of prior service cost included in net periodic pension cost		(1)	24	7	32
Defined Benefit Pension plans, Total		(1)	24	(432)	38
Other comprehensive (loss)/Income, before tax		(11,421)	398	(11,075)	7,601
Income tax (expenses) benefit related to other comprehensive income		(329)	224	(1,028)	(179)
Net current-period other comprehensive income (loss)		(11,750)	622	(12,103)	7,422
Comprehensive income		$ 29,398	$ 37,274	$ 74,684	$ 82,454
Earnings per share:
Basic		$ 0.49	$ 0.44	$ 1.04	$ 0.90
Diluted		$ 0.49	$ 0.44	$ 1.04	$ 0.89
Weighted average common shares outstanding:
Basic		83,130	83,818	83,130	83,807
Diluted		83,475	83,853	83,426	83,844

[1] Net revenues are attributed to regions based upon customer location.