Income Taxes - Components of Income (Loss) Before Taxes (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Operating Loss Carryforwards [Line Items]
Loss before income taxes	$ (19,566)	$ (16,340)	$ (19,920)
U.S.
Operating Loss Carryforwards [Line Items]
Loss before income taxes	(19,302)	(16,235)	(18,078)
Non U.S.
Operating Loss Carryforwards [Line Items]
Loss before income taxes	$ (264)	$ (105)	$ (1,842)