Property, Plant and Equipment, Net - Components of Property, Plant and Equipment (Detail) (USD $) In Thousands, unless otherwise specified	Jun. 30, 2014	Dec. 31, 2013
Property Plant And Equipment [Abstract]
Land	$ 260	$ 260
Buildings and improvements	4,965	4,125
Office furniture and equipment	3,347	2,723
Tooling and equipment	11,217	7,595
Transportation equipment	470	203
Construction in progress	5,582	4,844
Property, plant and equipment, at cost	25,841	19,750
Accumulated depreciation	(7,302)	(6,646)
Property, plant and equipment, net	$ 18,539	$ 13,104