CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Income Statement [Abstract]
Net sales	$ 288,669	$ 322,006	$ 569,386	$ 624,299
Cost of goods sold	187,177	200,018	372,052	389,900
Gross profit	101,492	121,988	197,334	234,399
Operating expenses
Selling, general and administrative	45,372	47,333	87,587	91,021
Research and development	21,322	21,707	45,000	43,877
Amortization of acquisition related intangible assets	4,021	4,536	8,242	9,020
Other operating (income)	(92)	(104)	(216)	(158)
Total operating expense	70,623	73,472	140,613	143,760
Income from operations	30,869	48,516	56,721	90,639
Other income (expense)
Interest income	168	633	441	1,508
Interest expense	(2,653)	(2,011)	(3,898)	(4,156)
Foreign currency loss, net	(3,600)	(496)	(3,525)	(560)
Other income	1,274	1,235	1,275	2,480
Total other expense	(4,811)	(639)	(5,707)	(728)
Income before income taxes and noncontrolling interest	26,058	47,877	51,014	89,911
Income tax provision	4,670	11,174	9,226	21,472
Net income	21,388	36,703	41,788	68,439
Less net income attributable to noncontrolling interest	(355)	(419)	(587)	(439)
Net income attributable to common stockholders	$ 21,033	$ 36,284	$ 41,201	$ 68,000
Earnings per share attributable to common stockholders:
Basic	$ 0.41	$ 0.72	$ 0.80	$ 1.35
Diluted	$ 0.40	$ 0.70	$ 0.78	$ 1.32
Number of shares used in earnings per share computation:
Basic	51,527	50,658	51,431	50,529
Diluted	52,569	51,620	52,517	51,566