Net Loss Per Share - Schedule of Anti-dilutive Equity Instruments Excluded from Calculation of Diluted Net Loss Per Share (Detail) - shares	9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020
Earnings Per Share Basic [Line Items]
Anti-dilutive securities excluded from calculation of diluted net loss per share	5,584,852	37,022,016
Awards under Equity Incentive Plan [Member]
Earnings Per Share Basic [Line Items]
Anti-dilutive securities excluded from calculation of diluted net loss per share	4,978,725	4,688,659
Nonvested Restricted Shares and Restricted Stock Units [Member]
Earnings Per Share Basic [Line Items]
Anti-dilutive securities excluded from calculation of diluted net loss per share	528,334	504,647
Warrants to Purchase Common Stock [Member]
Earnings Per Share Basic [Line Items]
Anti-dilutive securities excluded from calculation of diluted net loss per share	77,793	31,828,710