Annual report pursuant to Section 13 and 15(d)

Inventory (Details)

v3.19.1
Inventory (Details) - USD ($)
$ in Thousands
Dec. 31, 2018
Dec. 31, 2017
Inventory Disclosure [Abstract]    
Supplies $ 12,571 $ 9,437
Raw materials 199 219
Work in process 3,273 2,370
Finished goods 5,259 5,788
Total inventory $ 21,302 $ 17,814