Condensed Balance Sheets - USD ($) $ in Thousands	Mar. 31, 2020	Dec. 31, 2019
Current assets
Cash and cash equivalents	$ 2,325	$ 5,837
Accounts receivable, net of allowances of $0 and $0, respectively	552	1,079
Costs and estimated earnings in excess of billings on uncompleted contracts	0	0
Inventory	0	192
Other current assets	413	729
Total current assets	3,290	7,837
Property and equipment, net	1,733	1,849
Operating lease right-of-use asset	1,221	1,308
Restricted cash	435	435
Intangible assets	207	221
Other assets	18	186
Total assets	6,904	11,836
Current liabilities
Accounts payable	2,113	1,871
Accrued liabilities	837	2,045
Deferred revenue	15	21
Contract liabilities	9,271	9,755
Other current liabilities	42	83
Current portion of operating lease liability	661	656
Current portion of finance lease obligations	23	25
Total current liabilities	12,962	14,456
Operating lease liability, net of current portion	1,211	1,348
Finance lease obligations, net of current portion	5	9
Total liabilities	14,178	15,813
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; 130,878 and 125,803 shares issued and outstanding at March 31, 2020 and December 31, 2019, respectively	131	126
Additional paid-in capital	570,128	568,496
Accumulated deficit	(577,533)	(572,599)
Total shareholders' equity (deficit)	(7,274)	(3,977)
Total liabilities and shareholders' equity (deficit)	6,904	11,836
Reconciliation of cash, cash equivalents, and restricted cash balances
Cash and cash equivalents	2,325	5,837
Restricted cash	435	435
Cash, cash equivalents, and restricted cash	$ 2,760	$ 6,272