Intangible Assets - (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Components of Intangible assets
Cost	$ 33,586	$ 33,586
Accumulated amortization	(6,459)	(4,116)
Net	27,127	29,470
In-process research and development
Components of Intangible assets
Cost		15,956
Accumulated amortization		(177)
Net		$ 15,779
Weighted Average Remaining Life		14 years 10 months
Raw material supply agreement
Components of Intangible assets
Cost	6,230	$ 6,230
Accumulated amortization	(2,408)	(1,987)
Net	$ 3,822	$ 4,243
Weighted Average Remaining Life	8 years	9 years
Renewable diesel technology
Components of Intangible assets
Cost	$ 8,300	$ 8,300
Accumulated amortization	(1,983)	(1,429)
Net	$ 6,317	$ 6,871
Weighted Average Remaining Life	11 years 6 months	12 years 6 months
Acquired customer relationships
Components of Intangible assets
Cost	$ 2,900	$ 2,900
Accumulated amortization	(686)	(396)
Net	$ 2,214	$ 2,504
Weighted Average Remaining Life	7 years 7 months 15 days	8 years 7 months 15 days
Ground lease
Components of Intangible assets
Cost	$ 200	$ 200
Accumulated amortization	(141)	(127)
Net	$ 59	$ 73
Weighted Average Remaining Life	3 years 10 months 24 days	4 years 10 months 24 days
In-process research and development
Components of Intangible assets
Cost	$ 15,956
Accumulated amortization	(1,241)
Net	$ 14,715
Weighted Average Remaining Life	13 years 10 months