Significant Accounting Policies - Schedule of Computation of Diluted EPS (Detail) - shares	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Ownership cap in shares of common stock (as a percentage)	9.985%		9.985%
Outstanding stock options
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Potential common stock equivalents excluded from the computation of diluted net loss per share (shares)	5,152,024	4,364,943	5,152,024	4,364,943
Stock purchase warrants
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Potential common stock equivalents excluded from the computation of diluted net loss per share (shares)	157,500	159,506	157,500	159,506
Unvested restricted common stock awards
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Potential common stock equivalents excluded from the computation of diluted net loss per share (shares)	171,734	132,622	171,734	132,622
Convertible notes
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Potential common stock equivalents excluded from the computation of diluted net loss per share (shares)	5,040,323	5,040,323	5,040,323	5,040,323
Ownership cap in shares of common stock (as a percentage)	9.985%		9.985%