Condensed Consolidated Balance Sheets - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
Current assets
Cash and cash equivalents	$ 6,642	$ 13,766
Accounts receivable, net of allowances of $0 and $0, respectively	505	476
Costs and estimated earnings in excess of billings on uncompleted contracts	0	987
Inventory	241	1,109
Other current assets	574	1,311
Total current assets	7,962	17,649
Property and equipment, net	2,111	2,993
Operating lease right-of-use asset	1,394	0
Restricted cash	435	435
Intangible assets	306	486
Other assets	186	1,470
Total assets	12,394	23,033
Current liabilities
Accounts payable	1,091	2,411
Accrued liabilities	4,064	5,602
Deferred revenue	28	0
Contract liabilities	10,000	0
Other current liabilities	8	10,154
Current portion of operating lease liability	651	0
Current portion of finance lease obligations	24	21
Total current liabilities	15,866	18,188
Operating lease liability, net of current portion	1,482	0
Finance lease obligations, net of current portion	15	33
Deferred rent, net of current portion	0	695
Total liabilities	17,363	18,916
Commitments and contingencies (Note 10)
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; 119,417 and 100,105 shares issued and outstanding at September 30, 2019 and December 31, 2018, respectively	119	100
Additional paid-in capital	564,227	550,133
Accumulated deficit	(569,315)	(546,116)
Total shareholders' equity (deficit)	(4,969)	4,117
Total liabilities and shareholders' equity (deficit)	12,394	23,033
Reconciliation of cash, cash equivalents, and restricted cash balances
Cash and cash equivalents	6,642	13,766
Restricted cash	435	435
Cash, cash equivalents, and restricted cash	$ 7,077	$ 14,201