Inventories (Details) (USD $) In Thousands, unless otherwise specified	Sep. 30, 2012	Dec. 31, 2011
Inventories carried at LIFO [Abstract]
Finished goods	$ 36,005	$ 32,648
Raw materials, production parts and work-in-process	15,072	16,611
LIFO Reserve	(27,926)	(27,926)
Total LIFO inventories	23,151	21,333
Inventories carried at FIFO [Abstract]
Finished goods	25,514	31,912
Raw materials, production parts and work-in-process	12,288	12,667
Total FIFO inventories	37,802	44,579
Total Inventories	$ 60,953	$ 65,912