CONSOLIDATED STATEMENTS OF INCOME - USD ($) shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Income Statement [Abstract]
Net sales	$ 1,249,130	$ 1,213,989	$ 1,054,204
Cost of goods sold	783,323	778,713	697,428
Gross profit	465,807	435,276	356,776
Operating expenses
Selling, general and administrative	181,343	176,197	168,590
Research and development	88,517	86,286	77,877
Amortization of acquisition-related intangible assets	18,041	18,351	18,798
Impairment of fixed assets		390	2,211
Restructuring		206	10,137
Gain on disposal of fixed assets	(24,429)	(636)	(245)
Other operating expense (income)	1,727		(1)
Total operating expenses	265,199	280,794	277,367
Income from operations	200,608	154,482	79,409
Other income (expense)
Interest income	2,189	1,978	1,475
Interest expense	(7,893)	(9,901)	(13,448)
Foreign currency loss, net	(3,737)	(3,701)	(7,995)
Other income	7,079	7,104	3,150
Total other expense	(2,362)	(4,520)	(16,818)
Income before income taxes and noncontrolling interest	198,246	149,962	62,591
Income tax provision	44,131	44,556	62,325
Net income	154,115	105,406	266
Less: net income attributable to noncontrolling interest	(865)	(1,385)	(2,071)
Net income (loss) attributable to common stockholders	$ 153,250	$ 104,021	$ (1,805)
Earnings (loss) per share attributable to common stockholders
Basic	$ 3.02	$ 2.09	$ (0.04)
Diluted	$ 2.96	$ 2.04	$ (0.04)
Number of shares used in computation
Basic	50,787	49,841	48,824
Diluted	51,860	50,935	48,824