Condensed Consolidated Statements of Comprehensive Loss (Unaudited) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Statement of Comprehensive Income [Abstract]
Net loss	$ (5,360)	$ (8,479)	$ (10,922)	$ (14,854)
Other comprehensive income:
Unrealized gain on marketable securities, net of tax benefit of $454 and $463 for the three months and six months ended June 30, 2015 and $2 and $249 for the three months and six months ended June 30, 2014	776	4	792	406
Other comprehensive income	776	4	792	406
Total comprehensive loss	$ (4,584)	$ (8,475)	$ (10,130)	$ (14,448)