Stock-Based Compensation - Schedule of Components and Classification of Stock-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]
Stock-based compensation expense	$ 2,273	$ 1,750
Employee
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Stock-based compensation expense	2,239	1,551
Non-employee
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Stock-based compensation expense	34	199
Research and Development
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Stock-based compensation expense	1,058	1,033
General and Administrative
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Stock-based compensation expense	$ 1,215	$ 717