Nature of the Business and Basis of Presentation - Additional Information (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020	Dec. 31, 2020
Organization Consolidation And Presentation Of Financial Statements [Abstract]
Net loss	$ 17,983	$ 21,246	$ 53,578	$ 66,927
Accumulated deficit	458,147		458,147		$ 404,569
Net cash used in operating activities			56,890	$ 57,906
Cash, cash equivalents and available-for-sale securities	$ 229,760		$ 229,760