Inventories (Details) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2013	Dec. 31, 2012
Inventory Disclosure [Abstract]
Raw materials and work in process	$ 60,389	$ 66,221
Supplies and service parts	70,842	72,551
Finished products	63,925	68,335
Inventory at FIFO cost	195,156	207,107
Excess of FIFO cost over LIFO cost	(27,687)	(27,429)
Total inventory, net	$ 167,469	$ 179,678