Summary of Significant Accounting Policies - Schedule of Potentially Dilutive Securities Not Included in Calculation of Diluted Net Loss per Share (Detail) - shares	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Options to Purchase Common Stock [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Potentially dilutive securities not included in the calculation of diluted net loss per share	3,733,711	3,233,013
Warrants to Purchase Common Stock [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Potentially dilutive securities not included in the calculation of diluted net loss per share	250,539	250,646