CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS - USD ($) shares in Thousands, $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Income Statement [Abstract]
Net sales	$ 274,512	$ 236,303
Cost of goods sold	175,917	162,392
Gross profit	98,595	73,911
Operating expenses
Selling, general and administrative	47,150	39,690
Research and development	20,200	18,040
Amortization of acquisition related intangible assets	4,767	4,758
Restructuring	(320)	2,231
Other operating income	(142)	(165)
Total operating expenses	71,655	64,554
Income from operations	26,940	9,357
Other income (expense)
Interest income	514	295
Interest expense	(2,757)	(3,485)
Foreign currency loss, net	(3,029)	(3,794)
Other income (expense)	4,635	(271)
Total other income (expense)	(637)	(7,255)
Income before income taxes and noncontrolling interest	26,303	2,102
Income tax provision	7,783	560
Net income	18,520	1,542
Less net loss (income) attributable to noncontrolling interest	6	(325)
Net income attributable to common stockholders	$ 18,526	$ 1,217
Earnings per share attributable to common stockholders:
Basic	$ 0.38	$ 0.03
Diluted	$ 0.37	$ 0.02
Number of shares used in earnings per share computation:
Basic	49,337	48,316
Diluted	50,622	49,663