Inventories (Details) (USD $) In Thousands, unless otherwise specified	Jun. 30, 2012	Dec. 31, 2011
Inventory Disclosure [Abstract]
Raw materials and work in process	$ 68,456	$ 63,216
Supplies and service parts	72,552	68,600
Finished products	72,535	71,958
Inventory at FIFO cost	213,543	203,774
Excess of FIFO cost over LIFO cost	(25,981)	(25,175)
Total inventory, net	$ 187,562	$ 178,599