Consolidated Condensed Statements of (Loss) Income - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Income Statement [Abstract]
Product revenues	$ 136,061	$ 243,326	$ 364,674	$ 501,247
Type of Revenue [Extensible List]	us-gaap:ProductMember	us-gaap:ProductMember	us-gaap:ProductMember	us-gaap:ProductMember
Cost of sales	$ 109,326	$ 170,612	$ 271,872	$ 353,226
Gross margin	26,735	72,714	92,802	148,021
Operating expenses:
Net research and development expenses	15,341	19,255	33,101	38,152
Selling, general and administrative expenses	21,889	32,171	47,729	64,822
Restructuring expenses	(598)	1,231	3,168	3,145
Total operating expenses	36,632	52,657	83,998	106,119
Operating (loss) income	(9,897)	20,057	8,804	41,902
Interest expense, net	(1,361)	(1,240)	(2,109)	(2,608)
Foreign currency loss	(1,741)	(804)	(2,679)	(601)
Gain on sale of business				4,970
Impairment loss		(9,885)		(20,369)
Other income	2,882	171	3,146	314
(Loss) earnings before income tax	(10,117)	8,299	7,162	23,608
Income tax expense	205	5,548	5,611	12,443
Net (loss) income	$ (10,322)	$ 2,751	$ 1,551	$ 11,165
Basic (loss) earnings per share	$ (0.32)	$ 0.08	$ 0.05	$ 0.33
Diluted (loss) earnings per share	$ (0.32)	$ 0.08	$ 0.05	$ 0.33
Weighted average number of shares – basic	32,579,549	33,440,764	32,635,322	33,508,479
Weighted average number of shares – diluted	32,579,549	33,573,608	32,868,714	33,651,117