Inventories (Details) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2013	Dec. 31, 2012	Mar. 31, 2012
Inventory Disclosure [Abstract]
Raw materials	$ 14,180		$ 14,002
Work in progress	2,484		2,848
Finished goods	5,492		5,238
Supplies	915		868
Total Inventories	23,071		22,956
Inventory reserve	(73)		(61)
Net Inventories	$ 22,998	$ 22,895	$ 22,895