Condensed Consolidated Statement of Comprehensive Loss - 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	$ (12,078)	$ (12,261)	$ (24,084)	$ (23,798)
Unrealized gain (loss) on available-for-sale securities	3	(36)	81	(18)
Comprehensive loss	$ (12,075)	$ (12,297)	$ (24,003)	$ (23,816)