Nature of the Business and Basis of Presentation - Additional Information (Detail) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020	Dec. 31, 2020	Jan. 25, 2018
Nature Of Business And Basis Of Presentation [Line Items]
Net loss	$ 18,695	$ 18,987	$ 35,595	$ 45,681
Accumulated deficit	440,164		440,164		$ 404,569
Net cash used in operating activities			38,466	$ 42,342
Cash, cash equivalents and available-for-sale securities	$ 248,959		$ 248,959
Corporate Conversion [Member]
Nature Of Business And Basis Of Presentation [Line Items]
Common stock, conversion ratio						84.85%