Warrants - Additional Information (Detail) - USD ($) $ in Thousands	3 Months Ended	9 Months Ended		12 Months Ended
	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014	Dec. 31, 2009
Class of Warrant or Right [Line Items]
Warrants to purchase an aggregate of shares of common stock				8,206,520
Warrant term				5 years
Warrants expiration date		2014-12
Change in fair value of warrants	$ 5,847		$ 11,529
Warrants exercised			2,292,362
Conversion of Warrants to Common Stock			1,991,409
J. P. Morgan Securities LLC
Class of Warrant or Right [Line Items]
Warrants issued				464,520