Consolidated Condensed Statements of Income - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Income Statement [Abstract]
Product revenues	$ 257,921	$ 264,586
Type of Revenue [Extensible List]	us-gaap:ProductMember	us-gaap:ProductMember
Cost of sales	$ 182,614	$ 183,344
Gross margin	75,307	81,242
Operating expenses:
Net research and development expenses	18,897	23,304
Selling, general and administrative expenses	32,613	36,424
Acquisition transaction expenses	38
Restructuring expenses	1,914	865
Total operating expenses	53,462	60,593
Operating income	21,845	20,649
Interest expense	(1,368)	(1,180)
Foreign currency gain (loss)	203	(4,578)
Gain on sale of business	4,970
Impairment loss	(10,484)
Other income	143	1,111
Earnings before income tax	15,309	16,002
Income tax expense	6,895	3,036
Net income	$ 8,414	$ 12,966
Basic earnings per share	$ 0.25	$ 0.35
Diluted earnings per share	$ 0.25	$ 0.35
Weighted average number of shares – basic	33,573,411	36,766,411
Weighted average number of shares – diluted	33,733,335	36,873,407