Summary of Significant Accounting Policies - Anti-Dilutive Securities Excluded from the Computation of Diluted Net Loss per Share (Detail)	3 Months Ended		9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Anti-dilutive securities excluded from the computation of diluted loss per share	3,027,165	1,633,046	3,027,165	1,633,046
Warrants for common stock [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Anti-dilutive securities excluded from the computation of diluted loss per share	1,787,617	1,543,437	1,787,617	1,543,437
Common Stock [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Anti-dilutive securities excluded from the computation of diluted loss per share	992,033	89,609	992,033	89,609
Incentive awards [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Anti-dilutive securities excluded from the computation of diluted loss per share	247,515		247,515