Liquidity and Management's Plans - Additional Information (Detail) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Dec. 31, 2014	Dec. 31, 2013
Liquidity And Managements Plans [Abstract]
Cash and cash equivalents	$ 54,429	$ 85,794	$ 70,472	$ 23,176
Cash from operations	(32,717)	$ (10,799)
Stockholders' equity	19,702		$ 54,396
Potential milestone payment receivable upon regulatory approval	50,000
Deferred revenue recognized during the period	$ 6,000