Consolidated Statements of Comprehensive Loss - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Statement Of Income And Comprehensive Income [Abstract]
Net loss	$ (81,177)	$ (53,916)	$ (162,013)
Other comprehensive income (loss):
Net unrealized loss on available-for-sale investments	(226)	(95)	(268)
Income tax provision on unrealized gain on available-for-sale investments	0	0	470
Net foreign currency translation loss	(377)	(291)	(1,026)
Other comprehensive loss, net of tax	(603)	(386)	(824)
Comprehensive loss	$ (81,780)	$ (54,302)	$ (162,837)