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Net Loss per Share - Summary of Securities Not Included in Diluted Per Share Calculations (Detail) - shares
3 Months Ended
Mar. 31, 2017
Mar. 31, 2016
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]    
Antidilutive securities not included in the diluted per share calculations, amount 5,717,193 4,708,689
Option to purchase common stock [Member]    
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]    
Antidilutive securities not included in the diluted per share calculations, amount 4,380,299 3,371,795
Warrants to purchase common stock [Member]    
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]    
Antidilutive securities not included in the diluted per share calculations, amount 1,336,894 1,336,894