Share-Based Compensation - Summary of Share-based Compensation Expense (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Share-based compensation expense	$ 5,075	$ 3,153
Research and development
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Share-based compensation expense	1,371	1,170
General and administrative
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Share-based compensation expense	$ 3,704	$ 1,983