CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Income Statement [Abstract]
Net sales	$ 309,459	$ 323,674	$ 878,845	$ 947,973
Cost of goods sold	198,369	201,628	570,421	591,528
Gross profit	111,090	122,046	308,424	356,445
Operating expenses
Selling, general and administrative	44,651	46,123	132,238	137,143
Research and development	24,469	22,689	69,469	66,566
Amortization of acquisition related intangible assets	4,007	4,519	12,249	13,539
Other operating expense (income)	108		(108)	(158)
Total operating expense	73,235	73,331	213,848	217,090
Income from operations	37,855	48,715	94,576	139,355
Other income (expense)
Interest income	138	272	579	1,780
Interest expense	(3,745)	(2,007)	(7,643)	(6,163)
Foreign currency loss, net	(2,618)	(822)	(6,143)	(1,382)
Other income	1,627	2,577	2,902	5,056
Total other expense	(4,598)	20	(10,305)	(709)
Income before income taxes and noncontrolling interest	33,257	48,735	84,271	138,646
Income tax provision	5,871	10,613	15,097	32,085
Net income	27,386	38,122	69,174	106,561
Less net income attributable to noncontrolling interest	(234)	(62)	(821)	(501)
Net income attributable to common stockholders	$ 27,152	$ 38,060	$ 68,353	$ 106,060
Earnings per share attributable to common stockholders:
Basic	$ 0.52	$ 0.75	$ 1.33	$ 2.09
Diluted	$ 0.51	$ 0.73	$ 1.30	$ 2.05
Number of shares used in earnings per share computation:
Basic	51,825	50,998	51,563	50,687
Diluted	52,729	51,869	52,612	51,699