Stock Warrant - Additional Information (Detail) - USD ($) $ / shares in Units, $ in Thousands			1 Months Ended		3 Months Ended		9 Months Ended
	Sep. 30, 2015	Dec. 31, 2013	Aug. 31, 2015	Jul. 31, 2015	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014	Jul. 23, 2015
Convertible Preferred Stock Warrants [Line Items]
Convertible preferred stock warrant liability	$ 93	$ 158					$ 93
Change in the fair value of the warrant					$ (6)	$ 19	45	$ 74
Estimated fair value of the warrants issued to placement agents	$ 316				$ 316		$ 316
Insiders
Convertible Preferred Stock Warrants [Line Items]
Common stock issued as warrants			198,760	198,760
Common stock issued as warrants, exercise per share			$ 5.00	$ 5.00
Common stock warrants, expiry term			5 years	5 years
Term Loan | Series C Convertible Preferred Stock
Convertible Preferred Stock Warrants [Line Items]
Vested and exercisable warrant to purchase		128,231							128,231