Inventories (Details) (USD $) In Thousands, unless otherwise specified	Jun. 30, 2014	Dec. 31, 2013
Inventory Disclosure [Abstract]
Raw materials and work in process	$ 35,723	$ 33,920
Supplies and service parts	45,045	48,165
Finished products	35,218	38,515
Inventory at FIFO cost	115,986	120,600
Excess of FIFO cost over LIFO cost	(14,734)	(17,020)
Total inventory, net	$ 101,252	$ 103,580