Consolidated Statements of Operations - USD ($) shares in Thousands, $ in Thousands		12 Months Ended
		Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Income Statement [Abstract]
Revenue	[1]	$ 130,368	$ 121,244	$ 167,372
Cost of revenue		101,573	88,274	116,410
Gross profit		28,795	32,970	50,962
Operating expenses:
Selling, general and administrative		45,818	36,281	40,758
Research and development		18,351	20,889	24,697
Restructuring and exit costs		2,282	297	2,512
Impairment of assets		240	1,389	0
Total operating expenses		66,691	58,856	67,967
Loss from operations		(37,896)	(25,886)	(17,005)
Gain on sale of product line		0	(6,657)	0
Interest expense, net		1,355	248	284
Other income		(85)	(133)	0
Foreign currency exchange loss, net		306	216	441
Loss before income taxes		(39,472)	(19,560)	(17,730)
Income tax provision		3,657	4,145	4,603
Net loss		$ (43,129)	$ (23,705)	$ (22,333)
Net loss per share:
Basic and diluted		$ (1.22)	$ (0.74)	$ (0.73)
Weighted average common shares outstanding:
Basic and diluted		35,480	31,870	30,716

[1] Location is determined by shipment destination.