Nature of Business, Financial Condition and Basis of Presentation - Additional Information (Detail) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014	Apr. 15, 2015	Dec. 31, 2014	Dec. 31, 2013
Accounting Policies [Abstract]
Net loss	$ (6,519)	$ (938)	$ (28,232)	$ (30,066)
Deficit accumulated	(331,530)		(331,530)			$ (303,298)
Cash and cash equivalents	$ 16,203	$ 14,010	$ 16,203	$ 14,010		$ 6,359	$ 24,625
Common stock, par value	$ 0.01		$ 0.01		$ 0.01	$ 0.01
Reverse split of common stock			one-for-fifteen