Inventories (Details) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2014	Dec. 31, 2013
Inventory Disclosure [Abstract]
Raw materials and work in process	$ 34,084	$ 33,920
Supplies and service parts	44,284	48,165
Finished products	38,652	38,515
Inventory at FIFO cost	117,020	120,600
Excess of FIFO cost over LIFO cost	(16,064)	(17,020)
Total inventory, net	$ 100,956	$ 103,580