CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Income Statement [Abstract]
Net sales	$ 322,006	$ 304,085	$ 624,299	$ 578,597
Cost of goods sold	200,018	196,817	389,900	372,734
Gross profit	121,988	107,268	234,399	205,863
Operating expenses
Selling, general and administrative	47,333	42,153	91,021	89,303
Research and development	21,707	22,050	43,877	42,250
Amortization of acquisition related intangible assets	4,536	4,678	9,020	9,445
Other operating (income) expense	(104)	543	(158)	81
Total operating expense	73,472	69,424	143,760	141,079
Income from operations	48,516	37,844	90,639	64,784
Other income (expense)
Interest income	633	443	1,508	957
Interest expense	(2,011)	(2,544)	(4,156)	(5,301)
Foreign currency (loss) gain, net	(496)	300	(560)	(2,729)
Other income	1,235	377	2,480	5,012
Total other expense	(639)	(1,424)	(728)	(2,061)
Income before income taxes and noncontrolling interest	47,877	36,420	89,911	62,723
Income tax provision	11,174	10,753	21,472	18,536
Net income	36,703	25,667	68,439	44,187
Less net (income) attributable to noncontrolling interest	(419)	(599)	(439)	(593)
Net income attributable to common stockholders	$ 36,284	$ 25,068	$ 68,000	$ 43,594
Earnings per share attributable to common stockholders:
Basic	$ 0.72	$ 0.50	$ 1.35	$ 0.88
Diluted	$ 0.70	$ 0.49	$ 1.32	$ 0.86
Number of shares used in earnings per share computation:
Basic	50,658	49,680	50,529	49,509
Diluted	51,620	50,792	51,566	50,727