Fair Value Measurements - Schedule of Fair Value of Financial Assets Measured on Recurring Basis (Detail) - Fair Value Measurements Recurring [Member] - USD ($) $ in Thousands	Sep. 30, 2021	Dec. 31, 2020
Financial Assets
Total financial assets	$ 94,889	$ 102,219
Level 1 [Member]
Financial Assets
Total financial assets	94,889	102,219
Money Market Funds [Member]
Financial Assets
Total financial assets	94,589	101,919
Money Market Funds [Member] | Level 1 [Member]
Financial Assets
Total financial assets	94,589	101,919
Restricted Money Market Funds [Member]
Financial Assets
Total financial assets	300	300
Restricted Money Market Funds [Member] | Level 1 [Member]
Financial Assets
Total financial assets	$ 300	$ 300