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	$ (37,948)	$ (20,849)	$ (22,765)
Other comprehensive loss:
Unrealized gain (loss) on investment securities	45	(4)	9
Foreign currency translation adjustments	(1)	(1)	(512)
Comprehensive loss	$ (37,904)	$ (20,854)	$ (23,268)