CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Income Statement [Abstract]
Net sales	$ 304,085	$ 264,224	$ 578,597	$ 500,527
Cost of goods sold	196,817	174,085	372,734	336,477
Gross profit	107,268	90,139	205,863	164,050
Operating expenses
Selling, general and administrative	42,153	39,697	89,303	79,387
Research and development	22,050	19,796	42,250	37,836
Amortization of acquisition related intangible assets	4,678	4,646	9,445	9,404
Restructuring	526	1,838	206	4,069
Other operating expense (income)	17	334	(125)	169
Total operating expense	69,424	66,311	141,079	130,865
Income from operations	37,844	23,828	64,784	33,185
Other income (expense)
Interest income	443	308	957	603
Interest expense	(2,544)	(3,447)	(5,301)	(6,932)
Foreign currency gain (loss), net	300	(1,628)	(2,729)	(5,422)
Other income	377	802	5,012	531
Total other expense	(1,424)	(3,965)	(2,061)	(11,220)
Income before income taxes and noncontrolling interest	36,420	19,863	62,723	21,965
Income tax provision	10,753	6,039	18,536	6,599
Net income	25,667	13,824	44,187	15,366
Less net income attributable to noncontrolling interest	(599)	(645)	(593)	(970)
Net income attributable to common stockholders	$ 25,068	$ 13,179	$ 43,594	$ 14,396
Earnings per share attributable to common stockholders:
Basic	$ 0.50	$ 0.27	$ 0.88	$ 0.30
Diluted	$ 0.49	$ 0.26	$ 0.86	$ 0.29
Number of shares used in earnings per share computation:
Basic	49,680	48,518	49,509	48,418
Diluted	50,792	49,944	50,727	49,807