Inventory (Details) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Inventory.
Raw materials and supplies	$ 26,298	$ 23,705
Work-in-process	1,865	5,567
Finished goods	1,777	3,480
Total inventory	29,940	32,752
Inventory on consignment	$ 3,300	$ 2,200