Condensed Consolidated Statements of Comprehensive Loss (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Statement Of Income And Comprehensive Income [Abstract]
Net loss	$ (10,695)	$ (2,402)	$ (25,899)	$ (14,039)
Other comprehensive loss:
Unrealized gain (loss) on investment securities	110	3	80	(4)
Foreign currency translation adjustments		(1)		(1)
Comprehensive loss	$ (10,585)	$ (2,400)	$ (25,819)	$ (14,044)