Consolidated Balance Sheets (Current Period Unaudited) - USD ($) $ in Thousands	Mar. 31, 2020	Dec. 31, 2019
Current assets
Cash and cash equivalents	$ 58,279	$ 15,736
Investment securities		62,207
Prepaid expenses and other current assets	1,079	859
Total current assets	59,358	78,802
Property, plant and equipment, net	146,012	134,591
Operating lease right-of-use assets, net	730	1,054
Other non-current assets, net	12,677	6,748
Total assets	218,777	221,195
Current liabilities
Accounts payable	3,873	11,912
Share-based compensation liability	182	182
Accrued liabilities and other current liabilities	8,749	8,751
Current operating lease liabilities	430	698
Total current liabilities	13,234	21,543
Non-current Common Stock Warrant liabilities	3,696	12,034
Non-current operating lease liabilities		3
Other non-current liabilities	15,000
Total liabilities	31,930	33,580
Commitments and contingencies (Note 13)
Stockholders’ equity
Common stock, $0.0001 par value Authorized: 480.0 million shares at March 31, 2020 and December 31, 2019 Issued and outstanding: 117.4 million shares and 117.3 million shares at March 31, 2020 and December 31, 2019, respectively	12	12
Treasury stock: 149,167 shares and 137,860 shares at March 31, 2020 and December 31, 2019, respectively, at cost	(742)	(685)
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 March 31, 2020 and December 31, 2019
Additional paid-in-capital	218,972	224,091
Accumulated deficit	(132,799)	(133,701)
Total stockholders’ equity	85,443	89,717
Total liabilities, Series A and Series B Convertible Preferred Stock and stockholders’ equity	218,777	221,195
Series A Convertible Preferred Stock [Member]
Current liabilities
Convertible Preferred Stock	49,917	48,084
Series B Convertible Preferred Stock [Member]
Current liabilities
Convertible Preferred Stock	$ 51,487	$ 49,814