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)	$ 7,914	$ (14,436)	$ (8,412)	$ (38,845)
Other comprehensive income (loss):
Unrealized gain (loss) on available-for-sale securities	1	(2)	1	2
Comprehensive income (loss)	$ 7,915	$ (14,438)	$ (8,411)	$ (38,843)