Condensed Consolidated Statements of Comprehensive Loss - USD ($) $ in Thousands		3 Months Ended		9 Months Ended
		Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Statement of Comprehensive Income [Abstract]
Net loss		$ (1,988)	$ (10,226)	$ (10,417)	$ (23,966)
Other comprehensive income (loss)
Unrealized gain (loss) on marketable securities, net of tax	[1]	0	(90)	0	13
Other comprehensive income (loss)		0	(90)	0	13
Total comprehensive loss		$ (1,988)	$ (10,316)	$ (10,417)	$ (23,953)

[1] No tax benefit (expense) for three and nine months ended September 30, 2018. Net of tax expense of $52 and tax benefit of $8 for the three and nine months ended September 30, 2017, respectively.