Condensed Consolidated Statements of Cash Flows (Unaudited) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015
Operating activities:
Net loss	$ (4,735)	$ (10,922)
Adjustments to reconcile net loss to net cash provided by (used in) operating activities:
Amortization of intangible assets	1,687	1,687
Depreciation and amortization of property and equipment	924	1,080
Gain on disposal of property and equipment	(27)	(5)
Income tax benefit related to marketable securities	0	(463)
Stock-based compensation	2,631	2,536
Changes in operating assets and liabilities:
Accounts receivable, net	3,989	1,076
Inventories, net	(163)	427
Prepaid expenses and other current assets	190	221
Other assets	27	19
Accounts payable	(492)	(3,021)
Accrued compensation	(488)	(331)
Other accrued liabilities	601	(772)
Long term lease incentive	(212)	(212)
Deferred revenue	(3,745)	660
Net cash provided by (used in) operating activities	187	(8,020)
Investing activities:
Purchase of property and equipment	(474)	(183)
Proceeds from sale of property and equipment	27	5
Increase in restricted cash	0	(75)
Net cash used in investing activities	(447)	(253)
Financing activities:
Proceeds from exercises of options to purchase common stock	837	195
Taxes paid related to net share settlement of equity awards	(1,498)	(1,811)
Net cash used in financing activities	(661)	(1,616)
Net decrease in cash and cash equivalents	(921)	(9,889)
Cash and cash equivalents at the beginning of the period	23,273	26,487
Cash and cash equivalents at the end of the period	$ 22,352	$ 16,598