Condensed Consolidated Statements of Operations (Unaudited) - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Income Statement [Abstract]
Revenue	$ 29,464	$ 37,103	$ 57,880	$ 63,789
Cost of revenue	24,036	29,350	46,771	49,928
Gross profit	5,428	7,753	11,109	13,861
Operating expenses:
Selling, general and administrative	9,787	12,120	19,359	21,712
Research and development	5,549	4,449	11,081	9,155
Restructuring and exit costs	78	0	21	997
Total operating expenses	15,414	16,569	30,461	31,864
Loss from operations	(9,986)	(8,816)	(19,352)	(18,003)
Interest expense, net	1,030	97	2,023	160
Other components of defined benefit plans, net	(211)	(143)	(432)	(298)
Other income	(41)	(52)	(41)	(53)
Foreign currency exchange loss, net	238	18	327	115
Loss before income taxes	(11,002)	(8,736)	(21,229)	(17,927)
Income tax provision (benefit)	300	1,382	(722)	2,590
Net loss	$ (11,302)	$ (10,118)	$ (20,507)	$ (20,517)
Net loss per share
Basic and diluted (in dollars per share)	$ (0.30)	$ (0.28)	$ (0.54)	$ (0.61)
Weighted average common shares outstanding:
Weighted average common shares outstanding, basic and diluted	38,068	35,526	37,797	33,871