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
	Mar. 31, 2014	Mar. 31, 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	732,090	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
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
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
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	634,750	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	1,340