Consolidated Statements of Comprehensive Loss (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Statement Of Income And Comprehensive Income [Abstract]
Net loss	$ (162,013)	$ (171,855)	$ (133,978)
Other comprehensive income (loss):
Net unrealized gain (loss) on available-for-sale investments	(268)	1,206	(783)
Income tax provision (benefit) on unrealized gain on available-for-sale investments	470	(470)
Net foreign currency translation gain (loss)	(1,026)	10	(1,288)
Other comprehensive income (loss), net of tax	(824)	746	(2,071)
Comprehensive loss	$ (162,837)	$ (171,109)	$ (136,049)