Consolidated Balance Sheets - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017
Current assets
Cash and cash equivalents	$ 33,880	$ 35,703
Investments	60,135	5,063
Prepaid expenses and other current assets	1,804	2,099
Total current assets	95,819	42,865
Property, plant and equipment, net	88,870	73,226
Total assets	184,689	116,091
Current liabilities
Accounts payable	991	726
Share-based compensation liability	6,394	1,815
Accrued liabilities and other current liabilities	14,556	5,856
Total current liabilities	21,941	8,397
Non-current common stock warrant liabilities	7,522
Non-current compensation liabilities		2,015
Non-current share-based compensation liability		2,587
Total liabilities	29,463	12,999
Commitments and contingencies (Note 10)
Stockholders’ equity
Common stock, $0.0001 par value Authorized: 480.0 million shares at September 30, 2018 and December 31, 2017 Issued and outstanding: 106.8 million shares and 106.3 million shares at September 30, 2018 and December 31, 2017, respectively	11	11
Treasury stock: 3,202 shares and zero shares at September 30, 2018 and December 31, 2017, respectively, at cost	(19)
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, 2018 and December 31, 2017
Additional paid-in-capital	176,274	158,738
Accumulated deficit	(86,019)	(55,617)
Accumulated other comprehensive loss		(40)
Total stockholders’ equity	90,247	103,092
Total liabilities, Series A and Series B Convertible Preferred Stock and stockholders’ equity	184,689	116,091
Series A Convertible Preferred stock
Current liabilities
Convertible preferred stock	38,820	0
Series B Convertible Preferred stock
Current liabilities
Convertible preferred stock	$ 26,159	$ 0