Consolidated Balance Sheets - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017
Current assets
Cash and cash equivalents	$ 13,210	$ 16,966
Accounts receivable, net of allowances of $0 and $26, respectively	5,044	15
Costs and estimated earnings in excess of billings on uncompleted contracts	1,080	680
Inventory	3,347	4,541
Other current assets	893	1,015
Total current assets	23,574	23,217
Property and equipment, net	2,954	3,251
Restricted cash	435	435
Intangible assets	515	602
Other assets	2,492	2,262
Total assets	29,970	29,767
Current liabilities
Accounts payable	1,631	3,063
Accrued liabilities	5,719	5,864
Deferred revenue		0
Billings on uncompleted contracts in excess of related costs	1	5
Other current liabilities	10,027	10,142
Current portion of capital lease obligations	13	0
Total current liabilities	17,391	19,074
Capital lease obligations, net of current portion	27	0
Deferred revenue, net of current portion		0
Deferred rent, net of current portion	504	302
Other long-term liabilities	0	305
Total liabilities	17,922	19,681
Commitments and contingencies (Note 8)
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; 93,073 and 78,597 shares issued and outstanding at September 30, 2018 and December 31, 2017, respectively	93	79
Additional paid-in capital	546,123	528,873
Accumulated deficit	(534,168)	(518,866)
Total shareholders' equity	12,048	10,086
Total liabilities and shareholders' equity	29,970	29,767
Reconciliation of cash, cash equivalents, and restricted cash balances
Cash and cash equivalents	13,210	16,966
Restricted cash	435	435
Cash, cash equivalents, and restricted cash	$ 13,645	$ 17,401