Consolidated Balance Sheets - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Current assets
Cash and cash equivalents	$ 13,766	$ 16,966
Accounts receivable, net of allowances of $0 and $26, respectively	476	15
Costs and estimated earnings in excess of billings on uncompleted contracts	987	680
Inventory	1,109	4,541
Other current assets	1,311	1,015
Total current assets	17,649	23,217
Property and equipment, net	2,993	3,251
Restricted cash	435	435
Intangible assets	486	602
Other assets	1,470	2,262
Total assets	23,033	29,767
Current liabilities
Accounts payable	2,411	3,063
Accrued liabilities	5,602	5,864
Billings on uncompleted contracts in excess of related costs	0	5
Other current liabilities	10,154	10,142
Current portion of capital lease obligations	21	0
Total current liabilities	18,188	19,074
Capital lease obligations, net of current portion	33	0
Deferred rent, net of current portion	695	302
Other long-term liabilities	0	305
Total liabilities	18,916	19,681
Commitments and contingencies (Note 12)
Shareholders' equity
Preferred stock, par value $0.001; 25,000 shares authorized; 0 and 0 shares issued and outstanding	0	0
Common stock, par value $0.001; 150,000 shares authorized; 100,105 and 78,597 shares issued and outstanding at December 31, 2018 and 2017, respectively	100	79
Additional paid-in capital	550,133	528,873
Accumulated deficit	(546,116)	(518,866)
Total shareholders' equity	4,117	10,086
Total liabilities and shareholders' equity	23,033	29,767
Reconciliation of cash, cash equivalents, and restricted cash balances
Cash and cash equivalents	13,766	16,966
Restricted cash	435	435
Cash, cash equivalents, and restricted cash	$ 14,201	$ 17,401