Inventories (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Inventory Disclosure [Abstract]
Raw materials	$ 13,514	$ 8,229
Supplies and service parts	21,840	21,841
Finished products	36,969	36,692
Inventory at FIFO cost, net	72,323	66,762
Excess of FIFO cost over LIFO cost	(4,072)	(4,483)
Total inventory, net	$ 68,251	$ 62,279