Consolidated Statements of Cash Flow $ in Thousands	12 Months Ended
	Dec. 31, 2015 USD ($)	Dec. 31, 2014 USD ($)	Dec. 31, 2013 USD ($)
Cash flows from operating activities
Net income (loss)	$ 14,678	$ (11,266)	$ (17,144)
Adjustments to reconcile net income (loss) to net cash provided by (used for) operating activities:
Depreciation and amortization	4,869	4,589	5,075
Gain on sale of dry strip assets and intellectual property			(1,167)
Deferred taxes	779	1,266	(1,465)
Stock-based compensation expense	5,575	4,812	4,337
Provision for inventory reserves	1,721	1,817	2,562
Changes in operating assets & liabilities
Accounts receivable	5,171	(7,069)	(11,528)
Inventories	(15,938)	(12,280)	2,209
Prepaid expenses and other current assets	640	(1,384)	125
Accounts payable and other current liabilities	5,997	772	7,308
Deferred revenue	1,360	2,577	(2,181)
Income taxes	(46)	(212)	133
Other assets and liabilities	(6,547)	333	(3,306)
Net cash provided by (used for) operating activities	18,259	(16,045)	(15,042)
Cash flows from investing activities
Proceeds from sale of dry strip assets and intellectual property			1,200
Expenditures for property, plant and equipment	(1,830)	(896)	(821)
Decrease in restricted cash			106
Net cash (used for) provided by investing activities	(1,830)	(896)	485
Cash flows from financing activities
Increase in restricted cash	(6,111)		(825)
Financing fees and other expenses	(847)	(115)	(560)
Proceeds from exercise of stock options	3,921	2,895	1,669
Proceeds from Employee Stock Purchase Plan	441	446	436
Principal payments on sale leaseback obligation	(392)
Proceeds from financing obligations	48,940		15,000
Principal payments on Term Loan	(14,530)	(470)
Net cash provided by financing activities	31,422	2,756	15,720
Effect of exchange rate changes on cash	285	(1,352)	141
Net increase (decrease) in cash and cash equivalents	48,136	(15,537)	1,304
Cash and cash equivalents at beginning of period	30,753	46,290	44,986
Cash and cash equivalents at end of period	78,889	30,753	46,290
Supplemental disclosure of cash flow information
Cash paid for Income taxes	669	931	737
Cash paid for Interest paid	3,985	832	409
Supplemental disclosure of total cash, cash equivalents, short-term and long-term restricted cash at end of year:
Cash and cash equivalents at end of period	78,889	30,753	46,290
Short-term and long-term restricted cash at end of year	6,936	825	825
Total cash, cash equivalents and restricted cash at end of year	$ 85,825	$ 31,578	$ 47,115