Property, Plant and Equipment (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Property, Plant and Equipment
Total property, plant and equipment, net	$ 92,070	$ 73,226
Depreciation expense	171	106
Non project assets
Property, Plant and Equipment
Property, plant and equipment, gross	900	579
Less: accumulated depreciation	(542)	(371)
Total property, plant and equipment, net	358	208
Computers
Property, Plant and Equipment
Property, plant and equipment, gross	164	69
Furniture, fixtures, and equipment
Property, Plant and Equipment
Property, plant and equipment, gross	316	246
Leasehold improvements
Property, Plant and Equipment
Property, plant and equipment, gross	420	264
Project assets
Property, Plant and Equipment
Project assets in progress	91,712	73,018
Rio Grande
Property, Plant and Equipment
Project assets in progress	80,407	62,866
Rio Bravo
Property, Plant and Equipment
Project assets in progress	$ 11,305	$ 10,152