Inventories (Details) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2014	Dec. 31, 2013	Mar. 31, 2013	Dec. 31, 2012
Inventory Disclosure [Abstract]
Raw materials	$ 32,085	$ 28,592
Work in process	2,474	2,286
Finished goods	915	1,841
Inventory, gross	35,474	32,719
Less: Allowance for excess and obsolete inventories	(583)	(579)	(532)	(363)
Total, net	$ 34,891	$ 32,140