Inventories (Details) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2011	Dec. 31, 2010
Inventory, Net [Abstract]
Raw materials and work in process	$ 63,216	$ 60,465
Supplies and service parts	68,600	65,878
Finished products	71,958	68,941
Inventory at FIFO cost	203,774	195,284
Excess of FIFO cost over LIFO cost	(25,175)	(26,317)
Total	$ 178,599	$ 168,967