Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Operating activities:
Net loss	$ (2,602)	$ (11,799)	$ (27,953)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation and amortization	1,904	2,931	4,006
Long-lived assets write-off due to restructuring			1,011
Loss on disposal of fixed assets	1
Provision for adjustments to accounts receivable and doubtful accounts	31	347	730
Provision for excess and obsolete inventory	48	124	76
Tax benefits from stock-based compensation	(5)
Non cash compensation related to stock options and restricted stock	2,158	3,652	3,533
Deferred income taxes		(2)
Change in operating accounts:
Accounts receivable	40	(1,000)	660
Income tax receivable	688	(7)	(18)
Inventories	10	(54)	(67)
Prepaid expenses and other assets	92	114	(9)
Accounts payable and accrued liabilities	(1,362)	(2,189)	2,429
Deferred revenue	(1,058)	1,034	(972)
Net cash used in operating activities	(55)	(6,849)	(16,574)
Investing activities:
Capital expenditures	(124)	(216)	(829)
Sales (purchases) of short-term investments	(1,199)	198	10,257
Net cash provided by (used in) investing activities	(1,323)	(18)	9,428
Financing activities:
Cash received from issuance of common stock, net of offering costs		5,242
Cash received from stock sale for employee stock purchase plan	17	21	36
Cash received from exercise of stock options	10	6
Tax benefits received from stock-based compensation	5
Net cash provided by financing activities	32	5,269	36
Net decrease in cash and cash equivalents	(1,346)	(1,598)	(7,110)
Cash and cash equivalents, beginning of period	10,165	11,763	18,873
Cash and cash equivalents, end of period	8,819	10,165	11,763
Supplemental disclosures of cash flow information:
Cash paid for income taxes	17	$ 75	165
Change in unrealized gain (loss) on short-term investments	$ (1)		$ 7