Consolidated Statements of Cash Flow $ in Thousands	12 Months Ended
	Dec. 31, 2016 USD ($)	Dec. 31, 2015 USD ($)	Dec. 31, 2014 USD ($)
Cash flows from operating activities
Net income	$ 11,001	$ 14,678	$ (11,266)
Adjustments to reconcile net income to net cash (used in) provided by operating activities:
Depreciation and amortization	4,258	4,869	4,589
Gain on sale of equipment	(248)
Deferred taxes	519	779	1,266
Stock-based compensation expense	5,179	5,575	4,812
Provision for doubtful accounts	106
Provision for excess and obsolete inventory	1,051	1,721	1,817
Changes in operating assets & liabilities:
Accounts receivable	(14,135)	5,171	(7,069)
Inventories	(6,572)	(15,938)	(12,280)
Prepaid expenses and other current assets	(1,056)	640	(1,384)
Accounts payable and other current liabilities	799	5,997	772
Deferred revenue	2,467	1,360	2,577
Income taxes	102	(46)	(212)
Other assets and liabilities	(12,270)	(6,547)	333
Net cash (used in) provided by operating activities	(8,799)	18,259	(16,045)
Cash flows from investing activities
Proceeds from sale of equipment	270
Expenditures for property, plant, and equipment	(2,506)	(1,830)	(896)
Net cash used in investing activities	(2,236)	(1,830)	(896)
Cash flows from financing activities
Decrease in restricted cash	72	(6,111)
Financing fees and other expenses	(146)	(847)	(115)
Proceeds from exercise of stock options	2,227	3,921	2,895
Proceeds from Employee Stock Purchase Plan	277	441	446
Principal payments on sale leaseback obligation		(392)
Proceeds from financing obligations		48,940
Principal payments on Term Loan		(14,530)	(470)
Net cash provided by financing activities	2,430	31,422	2,756
Effect of exchange rate changes on cash and cash equivalents	507	285	(1,352)
Net (decrease) increase in cash and cash equivalents	(8,098)	48,136	(15,537)
Cash and cash equivalents at beginning of period	78,889	30,753	46,290
Cash and cash equivalents at end of period	70,791	78,889	30,753
Supplemental disclosure of cash flow information
Cash paid for Income taxes	525	669	931
Cash paid for Interest	4,815	3,985	832
Supplemental disclosure of total cash, cash equivalents and restricted cash:
Cash and cash equivalents at end of period	70,791	78,889	30,753
Restricted cash at end of period	6,864	6,936	825
Total cash, cash equivalents and restricted cash at end of period	$ 77,655	$ 85,825	$ 31,578