Condensed Consolidated Statements of Comprehensive Loss (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013
Statement of Comprehensive Income [Abstract]
Net loss	$ (8,479)	$ (12,605)	$ (14,854)	$ (22,228)
Other comprehensive income:
Unrealized gain on marketable securities, net of tax of $2 and $249 for the three months and six months ended June 30, 2014, respectively, and $32 and $155 for the three months and six months ended June 30, 2013, respectively.	4	50	406	242
Other comprehensive income	4	50	406	242
Total comprehensive loss	$ (8,475)	$ (12,555)	$ (14,448)	$ (21,986)