Consolidated Condensed Statements of Income - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Income Statement [Abstract]
Product revenues	$ 261,889	$ 249,267
Cost of sales	183,322	164,107
Gross margin	78,567	85,160
Operating expenses:
Net research and development expenses	23,304	19,505
Selling, general and administrative expenses	34,592	30,806
Total operating expenses	57,896	50,311
Operating income	20,671	34,849
Interest expense	(1,180)	(1,122)
Foreign currency loss	(4,578)	(1,329)
Other income	1,089	236
Earnings before income tax	16,002	32,634
Income tax expense	3,036	7,232
Net income	$ 12,966	$ 25,402
Basic earnings per share	$ 0.35	$ 0.69
Diluted earnings per share	$ 0.35	$ 0.69
Weighted average number of shares – basic	36,766,411	36,619,825
Weighted average number of shares – diluted	36,873,407	36,739,282