Condensed Consolidated Balance Sheets - USD ($) $ in Thousands	Mar. 31, 2017	Dec. 31, 2016
Current assets
Cash and cash equivalents	$ 7,655	$ 15,139
Accounts receivable, net of allowances of $26 and $26, respectively	160	245
Costs and estimated earnings in excess of billings on uncompleted contracts	309	125
Inventory	2,052	1,233
Other current assets	810	606
Total current assets	10,986	17,348
Property and equipment, net	2,569	1,537
Restricted cash	435	435
Intangible assets	689	718
Other assets	144	68
Total assets	14,823	20,106
Current liabilities
Accounts payable	2,237	2,195
Accrued liabilities	4,219	3,882
Deferred revenue	999	999
Billings on uncompleted contracts in excess of related costs	127	168
Total current liabilities	7,582	7,244
Deferred revenue, net of current portion	4,903	5,150
Deferred rent, net of current portion	143	185
Other long-term liabilities	45	53
Total liabilities	12,673	12,632
Commitments and contingencies (Note 6)
Shareholders' equity
Preferred stock, par value $0.001; 25,000 shares authorized; zero and zero shares issued and outstanding	0	0
Common stock, par value $0.001; 100,000 shares authorized; 68,122 and 68,093 shares issued and outstanding	68	68
Additional paid-in capital	507,572	507,249
Accumulated deficit	(505,490)	(499,843)
Total shareholders' equity	2,150	7,474
Total liabilities and shareholders' equity	$ 14,823	$ 20,106