Inventories - Summary of inventories (Details) - USD ($) $ in Thousands	Sep. 30, 2015		Dec. 31, 2014
Inventory Disclosure [Abstract]
Raw material and common parts, net of reserve	$ 6,883		$ 6,680
Work-in-process, net of reserve	3,229		2,280
Finished goods, net of reserve	2,582		3,080
Total inventories	$ 12,694	[1]	$ 12,040

[1] (Unaudited)