Consolidated Balance Sheets (Current Period Unaudited) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
Current assets
Cash and cash equivalents	$ 3,841	$ 3,169
Investment securities	40,374	72,453
Prepaid expenses and other current assets	1,288	1,310
Total current assets	45,503	76,932
Property, plant and equipment, net	119,918	92,070
Operating lease right-of-use assets, net	1,336
Other non-current assets	3,071
Total assets	169,828	169,002
Current liabilities
Accounts payable	1,400	719
Share-based compensation liability	182	3,018
Accrued liabilities and other current liabilities	19,911	8,353
Current operating lease liabilities	1,512
Total current liabilities	23,005	12,090
Non-current common stock warrant liabilities	10,343	7,441
Non-current operating lease liabilities	10
Total liabilities	33,358	19,531
Commitments and contingencies (Note 12)
Stockholders’ equity
Common stock, $0.0001 par value Authorized: 480.0 million shares at September 30, 2019 and December 31, 2018, Issued and outstanding: 107.2 million shares and 106.9 million shares at September 30, 2019 and December 31, 2018, respectively	11	11
Treasury stock: 137,860 shares and 6,425 shares at September 30, 2019 and December 31, 2018, respectively, at cost	(685)	(35)
Preferred stock, $0.0001 par value Authorized: 0.9 million, after designation of the Series A and Series B Convertible Preferred Stock, Issued and outstanding: none at September 30, 2019 and December 31, 2018, respectively
Additional paid-in-capital	162,590	180,862
Accumulated deficit	(119,820)	(97,617)
Total stockholders’ equity	42,096	83,221
Total liabilities, Series A and Series B Convertible Preferred Stock and stockholders’ equity	169,828	169,002
Series A Convertible Preferred Stock [Member]
Current liabilities
Convertible Preferred Stock	46,186	40,091
Series B Convertible Preferred Stock [Member]
Current liabilities
Convertible Preferred Stock	$ 48,188	$ 26,159