Consolidated Balance Sheets - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
Current assets
Cash and cash equivalents	$ 24,705	$ 35,703
Investments	5,065	5,063
Prepaid expenses and other current assets	2,282	2,099
Total current assets	32,052	42,865
Property, plant and equipment, net	79,364	73,226
Total assets	111,416	116,091
Current liabilities
Accounts payable	247	726
Share-based compensation liability	1,949	1,815
Accrued liabilities and other current liabilities	5,469	5,856
Total current liabilities	7,665	8,397
Non-current compensation liabilities	1,000	2,015
Non-current share-based compensation liability	3,419	2,587
Total liabilities	12,084	12,999
Commitments and contingencies (Note 9)
Stockholders’ equity
Preferred stock, $0.0001 par value, 1.0 million shares authorized, none issued
Common stock	11	11
Additional paid-in-capital	171,178	158,738
Accumulated deficit	(71,857)	(55,617)
Accumulated other comprehensive loss		(40)
Total stockholders’ equity	99,332	103,092
Total liabilities and stockholders’ equity	$ 111,416	$ 116,091