Consolidated Statements of Income - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Income Statement [Abstract]
Product revenues	$ 913,098	$ 971,684	$ 1,048,505
Type of Revenue [Extensible List]	us-gaap:ProductMember	us-gaap:ProductMember	us-gaap:ProductMember
Cost of sales	$ 644,994	$ 683,349	$ 743,647
Gross margin	268,104	288,335	304,858
Operating expenses:
Research and development expenses	81,968	91,033	98,663
Reimbursed research and development expenses	(13,928)	(18,557)	(18,763)
Net research and development expenses	68,040	72,476	79,900
Selling, general and administrative expenses	105,044	118,680	137,398
Restructuring expenses	5,803	12,919	14,772
Total operating expenses	178,887	204,075	232,070
Operating income	89,217	84,260	72,788
Interest expense, net	(4,559)	(4,763)	(4,942)
Foreign currency (loss) gain	(5,439)	2,326	622
Impairment loss		(21,206)	(11,476)
Net loss on divestitures		(1,587)
Other income	2,337	121	1,127
Earnings before income tax	81,556	59,151	58,119
Income tax expense	21,866	10,285	16,220
Net income	$ 59,690	$ 48,866	$ 41,899
Basic earnings per share	$ 1.83	$ 1.48	$ 1.17
Diluted earnings per share	$ 1.81	$ 1.47	$ 1.16
Weighted average number of shares – basic	32,666,025	33,120,076	35,920,782
Weighted average number of shares – diluted	33,028,104	33,297,589	36,177,144