Net Loss Per Common Share - Summary of Calculation of the Diluted Net Loss per Common Share (Detail) - shares	6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Shares issuable	20,125,574	17,106,180
Conversion of Series A Preferred Stock [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Shares issuable	391,210	391,210
Conversion of Series B Preferred Stock [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Shares issuable	3,088,444	3,088,444
Conversion of Series C Preferred Stock [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Shares issuable	4,499,921	4,499,921
Conversion of Series D Preferred Stock [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Shares issuable	8,593,360	6,418,437
Exercise of Stock Options [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Shares issuable	2,596,087	1,751,616
Exercise of Common Stock Warrants [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Shares issuable	509,562	509,562
Exercise of Preferred Stock Warrants [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Shares issuable	446,990	446,990