Consolidated Balance Sheets - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018
Current assets
Cash and cash equivalents	$ 6,979	$ 13,766
Accounts receivable, net of allowances of $0 and $0, respectively	274	476
Costs and estimated earnings in excess of billings on uncompleted contracts	1,199	987
Inventory	1,062	1,109
Other current assets	1,091	1,311
Total current assets	10,605	17,649
Property and equipment, net	2,675	2,993
Operating lease right-of-use asset	1,559	0
Restricted cash	435	435
Intangible assets	457	486
Other assets	1,470	1,470
Total assets	17,201	23,033
Current liabilities
Accounts payable	2,003	2,411
Accrued liabilities	5,092	5,602
Billings on uncompleted contracts in excess of related costs	5	0
Other current liabilities	10,095	10,154
Current portion of operating lease liability	642	0
Current portion of finance lease obligations	22	21
Total current liabilities	17,859	18,188
Operating lease liability, net of current portion	1,746	0
Finance lease obligations, net of current portion	28	33
Deferred rent, net of current portion	0	695
Total liabilities	19,633	18,916
Commitments and contingencies (Note 9)
Shareholders' equity (deficit)
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; 102,105 and 100,105 shares issued and outstanding at March 31, 2019 and December 31, 2018, respectively	102	100
Additional paid-in capital	551,650	550,133
Accumulated deficit	(554,184)	(546,116)
Total shareholders' equity (deficit)	(2,432)	4,117
Total liabilities and shareholders' equity (deficit)	17,201	23,033
Reconciliation of cash, cash equivalents, and restricted cash balances
Cash and cash equivalents	6,979	13,766
Restricted cash	435	435
Cash, cash equivalents, and restricted cash	$ 7,414	$ 14,201