Inventories (Details) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2012	Dec. 31, 2011
Inventories carried at LIFO:
Finished goods	$ 33,546	$ 32,648
Raw materials, production parts and work-in-process	14,291	16,611
LIFO Reserve	(27,608)	(27,926)
Total LIFO inventories	20,229	21,333
Inventories carried at FIFO:
Finished goods	25,623	31,912
Raw materials, production parts and work-in-process	12,284	12,667
Total FIFO inventories	37,907	44,579
Inventories	$ 58,136	$ 65,912