Consolidated Statements of Operations - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Income Statement [Abstract]
Net sales	$ 161,710	$ 148,105
Cost of sales	120,140	113,856
Gross profit	41,570	34,249
Operating expenses
Selling, general and administrative expenses	23,148	19,952
Research and development expenses	17,958	17,815
Restructuring gain and other	(17,010)	(7,785)
Early termination charges	11,107
Total operating expenses	35,203	29,982
Operating income	6,367	4,267
Interest expense	(5,173)	(4,057)
Foreign currency gain, net	41,786	8,195
Other income, net	1,611	535
Income before income taxes	44,591	8,940
Income tax expenses	853	815
Net income	$ 43,738	$ 8,125
Earnings per common share-
Basic	$ 1.30	$ 0.23
Diluted	$ 1.05	$ 0.23
Weighted average number of shares-
Basic	33,662,297	34,698,904
Diluted	42,892,044	34,918,568