Liquidity and Management's Plans - Additional Information (Detail) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Dec. 31, 2014	Dec. 31, 2013
Liquidity And Managements Plans [Abstract]
Cash and cash equivalents	$ 67,655	$ 78,364	$ 70,472	$ 23,176
Cash from operations	(19,350)	$ (8,738)
Stockholders' equity	34,920		$ 54,396
Potential milestone payment receivable upon regulatory approval	$ 50,000