Net Loss per Share - Schedule of Diluted Net Loss Per Share Attributable to Common Stockholders Anti-Diluted Effect (Detail) - shares	9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Anti-dilutive stock	5,785,042	32,545,331
Unvested Restricted Stock
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Anti-dilutive stock	133,317	261,354
Options to purchase Common Stock
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Anti-dilutive stock	5,651,725	1,953,647
Convertible Preferred Stock
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Anti-dilutive stock		30,330,330