Intangible Assets - (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Components of Intangible assets
Cost	$ 20,181	$ 20,181
Accumulated amortization	(8,163)	(6,535)
Net	12,018	13,646
Raw material supply agreement
Components of Intangible assets
Cost	6,230	6,230
Accumulated amortization	(3,368)	(2,866)
Net	2,862	3,364
Renewable diesel technology
Components of Intangible assets
Cost	8,300	8,300
Accumulated amortization	(3,089)	(2,536)
Net	5,211	5,764
Acquired customer relationships
Components of Intangible assets
Cost	4,747	4,747
Accumulated amortization	(1,535)	(976)
Net	3,212	3,771
Other intangible assets
Components of Intangible assets
Cost	904	904
Accumulated amortization	(171)	(157)
Net	$ 733	$ 747