Nature of the Business and Basis of Presentation - Additional Information (Detail) - USD ($) $ / shares in Units, $ in Thousands				1 Months Ended	12 Months Ended
	Dec. 15, 2020	Jul. 30, 2019	Jan. 30, 2018	Oct. 31, 2020	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	Jan. 25, 2018
Nature Of Business And Basis Of Presentation [Line Items]
Net proceeds from issuance					$ 113,208	$ 49,325
Gross proceeds from private placement	$ 90,000	$ 59,977
Offering costs					3,790	2,102	$ 2,168
Net loss					88,290	117,223	74,798
Accumulated deficit					404,569	316,279
Net cash used in operating activities					56,599	92,714	70,197
Cash and cash equivalents					$ 154,744	$ 76,043	$ 86,366
IPO [Member]
Nature Of Business And Basis Of Presentation [Line Items]
Stock issued and sold			8,984,375
Stock price per share			$ 16.00
Net proceeds from issuance			$ 129,096
Private Placement [Member]
Nature Of Business And Basis Of Presentation [Line Items]
Offering costs	$ 3,790	$ 2,102
Private Placement [Member] | Common Stock [Member]
Nature Of Business And Basis Of Presentation [Line Items]
Stock issued and sold	24,324,320	10,607,525
Stock price per share	$ 3.70	$ 4.65
Private Placement [Member] | Pre-Funded Warrants [Member]
Nature Of Business And Basis Of Presentation [Line Items]
Warrants to purchase common stock		2,295,699
Warrants price per share		$ 4.64
Warrants exercisable for common stock		1
Exercise price of warrant		$ 0.01
ATM Sales Agreement [Member]
Nature Of Business And Basis Of Presentation [Line Items]
Stock issued and sold				6,309,632
Net proceeds from issuance				$ 23,209
Corporate Conversion [Member]
Nature Of Business And Basis Of Presentation [Line Items]
Common stock, conversion ratio								84.85%