v3.19.3
Inventories (Details) - USD ($)
$ in Thousands
Sep. 30, 2019
Dec. 31, 2018
Inventory Disclosure [Abstract]    
Finished goods $ 19,919 $ 25,136
Raw materials 362 439
Parts, supplies and other 36,583 37,979
Total inventories $ 56,864 $ 63,554