Consolidated Statements of Comprehensive Loss - USD ($) $ in Thousands		12 Months Ended
		Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Statement of Comprehensive Income [Abstract]
Net loss		$ (8,558)	$ (7,581)	$ (19,071)
Other comprehensive income (loss):
Unrealized gain (loss) on marketable securities, net of tax	[1]	(405)	547	(110)
Other comprehensive income (loss)		(405)	547	(110)
Total comprehensive loss		$ (8,963)	$ (7,034)	$ (19,181)

[1] Net of benefit from income taxes of $0, $314, and $0 in 2016, 2015 and 2014, respectively.