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	$ (15,001)	$ (52,739)	$ (107,029)
Other comprehensive (loss) income:
Unrealized (losses) gains on available-for-sale securities	(3)	2	(9)
Foreign currency translation adjustment			26
Comprehensive loss	$ (15,004)	$ (52,737)	$ (107,012)