Inventories (Details) (USD $) In Thousands, unless otherwise specified	Sep. 30, 2013	Dec. 31, 2012
Inventories carried at LIFO:
Finished goods	$ 37,796	$ 33,546
Raw materials, production parts and work-in-process	13,555	14,291
LIFO Reserve	(27,608)	(27,608)
Total LIFO inventories	23,743	20,229
Inventories carried at FIFO:
Finished goods	31,582	25,623
Raw materials, production parts and work-in-process	12,065	12,284
Total FIFO inventories	43,647	37,907
Total inventories	$ 67,390	$ 58,136