Summary of Significant Accounting Policies - Summary of Weighted-Average Anti-Dilutive Securities Excluded from Calculation of Diluted Net Loss Per Share (Detail)	3 Months Ended		6 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Weighted-average anti-dilutive securities excluded from the calculation of diluted net loss per share	788,771	2,584,252	790,112	2,584,252
Convertible preferred stock outstanding [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Weighted-average anti-dilutive securities excluded from the calculation of diluted net loss per share		2,439,002		2,439,002
Warrants for convertible preferred stock [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Weighted-average anti-dilutive securities excluded from the calculation of diluted net loss per share		22,000		22,000
Warrants for common stock [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Weighted-average anti-dilutive securities excluded from the calculation of diluted net loss per share	96,000		96,000
Common stock options [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Weighted-average anti-dilutive securities excluded from the calculation of diluted net loss per share	688,750	123,250	688,750	123,250
Employee stock purchase plan [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Weighted-average anti-dilutive securities excluded from the calculation of diluted net loss per share	4,021		5,362