CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Income Statement [Abstract]
Net sales	$ 264,224	$ 236,645	$ 500,527	$ 459,383
Cost of goods sold	174,085	161,828	336,477	320,346
Gross profit	90,139	74,817	164,050	139,037
Operating expenses
Selling, general and administrative	39,697	41,390	79,387	80,844
Research and development	19,796	17,010	37,836	35,159
Amortization of acquisition related intangible assets	4,646	5,131	9,404	10,262
Restructuring expense	1,838		4,069
Other operating expenses	334	9	169	40
Total operating expenses	66,311	63,540	130,865	126,305
Income from operations	23,828	11,277	33,185	12,732
Other income (expense)
Interest income	308	298	603	754
Interest expense	(3,447)	(3,684)	(6,932)	(6,196)
Foreign currency (loss) gain, net	(1,628)	673	(5,422)	(606)
Other income	802	228	531	71
Total other income (expense)	(3,965)	(2,485)	(11,220)	(5,977)
Income before income taxes and noncontrolling interest	19,863	8,792	21,965	6,755
Income tax provision	6,039	2,396	6,599	1,844
Net income	13,824	6,396	15,366	4,911
Less net income attributable to noncontrolling interest	(645)	(644)	(970)	(892)
Net income attributable to common stockholders	$ 13,179	$ 5,752	$ 14,396	$ 4,019
Earnings per share attributable to common stockholders:
Basic	$ 0.27	$ 0.12	$ 0.30	$ 0.08
Diluted	$ 0.26	$ 0.12	$ 0.29	$ 0.08
Number of shares used in earnings per share computation:
Basic	48,518	48,383	48,418	48,336
Diluted	49,944	49,500	49,807	49,380