Inventories (Details) (USD $) In Thousands, unless otherwise specified	Jun. 30, 2013	Dec. 31, 2012
Inventory Disclosure [Abstract]
Raw materials and work in process	$ 53,187	$ 66,221
Supplies and service parts	65,478	72,551
Finished products	50,583	68,335
Inventory at FIFO cost	169,248	207,107
Excess of FIFO cost over LIFO cost	(28,187)	(27,429)
Total inventory, net	$ 141,061	$ 179,678