Nature of the Business - 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	$ 32,613	$ 36,780	$ 90,899	$ 91,581
Accumulated deficit	355,315		355,315		$ 264,416
Cash and cash equivalents	$ 201,369	$ 219,546	$ 201,369	$ 219,546	$ 259,682