Inventories (Details) - USD ($) $ in Thousands	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2013
Inventory Disclosure [Abstract]
Raw materials	$ 43,647		$ 34,153
Work in process	1,945		2,262
Finished goods	2,363		1,917
Inventory, gross	47,955		38,332
Less: Allowance for excess and obsolete inventories	(773)	$ (755)	(714)	$ (735)	$ (583)	$ (579)
Total, net	$ 47,182		$ 37,618