Inventories (Details) - USD ($) $ in Thousands	Sep. 30, 2016	Dec. 31, 2015
Inventory Disclosure [Abstract]
Raw materials	$ 35,228	$ 25,803
Work in process	8,512	6,408
Supplies and service parts	45,653	44,323
Finished products	31,701	24,618
Inventory at FIFO cost	121,094	101,152
Excess of FIFO cost over LIFO cost	(12,328)	(12,328)
Total inventory, net	$ 108,766	$ 88,824