Condensed Consolidated Statements of Cash Flows (Unaudited) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Operating activities:
Net loss	$ (7,460)	$ (6,974)
Adjustments to reconcile net loss to net cash provided by (used in) operating activities:
Amortization of intangible assets	0	844
Depreciation and amortization of property and equipment	326	465
Gain on disposal of property and equipment	(1)	(27)
Stock-based compensation	1,669	1,389
Changes in operating assets and liabilities:
Accounts receivable, net	543	2,977
Inventories	(299)	(30)
Prepaid expenses and other current assets	(174)	5
Restricted cash	(43)	0
Other assets	6	109
Accounts payable	(882)	(395)
Accrued compensation	1,020	974
Other accrued liabilities	763	1,172
Long term lease incentive	(106)	(106)
Other long term liabilities	(19)	0
Deferred revenue	1,048	(184)
Net cash provided by (used in) operating activities	(3,609)	219
Investing activities:
Purchase of property and equipment	(237)	(265)
Proceeds from disposal of property and equipment	1	27
Change in restricted cash	75	0
Net cash used in investing activities	(161)	(238)
Financing activities:
Proceeds from exercises of options	99	7
Principal payments on capital lease obligations	(10)	0
Taxes paid related to net share settlement of equity awards	(1,636)	(1,098)
Net cash used in financing activities	(1,547)	(1,091)
Net decrease in cash and cash equivalents	(5,317)	(1,110)
Cash and cash equivalents at the beginning of the period	19,240	23,273
Cash and cash equivalents at the end of the period	13,923	22,163
Noncash Investing and Financing Items [Abstract]
Equipment acquired under a capital lease	$ 528	$ 0