Inventories - Components of Inventories (Details) - USD ($) $ in Thousands	Sep. 30, 2017	Dec. 31, 2016
Inventory Disclosure [Abstract]
Raw materials	$ 5,003	$ 5,331
Work in process	1,864	2,337
Finished goods	3,802	3,975
Total inventories	$ 10,669	$ 11,643	[1]

[1] Derived from the audited consolidated financial statements included in the Annual Report on Form 10-K filed with the SEC for the year ended December 31, 2016.