Consolidated Balance Sheets - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Current assets
Cash and cash equivalents	$ 3,169	$ 35,703
Investment securities	72,453	5,063
Prepaid expenses and other current assets	1,310	2,099
Total current assets	76,932	42,865
Property, plant and equipment, net	92,070	73,226
Total assets	169,002	116,091
Current liabilities
Accounts payable	719	726
Share-based compensation liability	3,018	1,815
Accrued liabilities and other current liabilities	8,353	5,856
Total current liabilities	12,090	8,397
Non-current Common Stock Warrant liabilities	7,441
Non-current compensation liabilities		2,015
Non-current share-based compensation liability		2,587
Total liabilities	19,531	12,999
Commitments and contingencies (Note 12)
Stockholders’ equity
Common stock, $0.0001 par value Authorized: 480.0 million shares at December 31, 2018 and December 31, 2017 Issued and outstanding: 106.9 million shares and 106.3 million shares at December 31, 2018 and December 31, 2017, respectively	11	11
Treasury stock: 6,425 shares and zero shares at December 31, 2018 and December 31, 2017, respectively, at cost	(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 December 31, 2018 and December 31, 2017
Additional paid-in-capital	180,862	158,738
Accumulated deficit	(97,617)	(55,617)
Accumulated other comprehensive loss		(40)
Total stockholders’ equity	83,221	103,092
Total liabilities, Series A and Series B Convertible Preferred Stock and stockholders’ equity	169,002	116,091
Series A Convertible Preferred stock
Current liabilities
Convertible Preferred Stock	40,091	0
Series B Convertible Preferred stock
Current liabilities
Convertible Preferred Stock	$ 26,159	$ 0