Condensed Consolidated Statements of Comprehensive Income (Loss) (Unaudited) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Statement Of Income And Comprehensive Income [Abstract]
Net income (loss)	$ 567	$ (4,684)	$ (42,309)	$ (16,094)
Other comprehensive income:
Unrealized gain on marketable securities	75		75
Comprehensive income (loss)	$ 642	$ (4,684)	$ (42,234)	$ (16,094)