Net Loss per Share - Summary of Securities Not Included in Diluted Per Share Calculations (Detail) - shares	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities not included in the diluted per share calculations, amount	3,356,387	635,199
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	535,243	252,554
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	2,821,144	382,645