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 Income And Comprehensive Income [Abstract]
Net loss	$ (58,329)	$ (31,350)	$ (105,242)	$ (62,076)
Other comprehensive income (loss):
Unrealized gain (loss) on available-for-sale securities, net of tax	(21)	(5)	148	(33)
Total comprehensive loss	$ (58,350)	$ (31,355)	$ (105,094)	$ (62,109)