Fair Value Measurement - Summary of Financial Assets Measured at Fair Value on Recurring Basis (Detail) - Fair Value on Recurring Basis [Member] - USD ($) $ in Thousands	Sep. 30, 2021	Dec. 31, 2020
Assets Fair Value Disclosure
Assets Fair Value Disclosure	$ 200,433	$ 44,416
Money Market Funds [Member] | Cash Equivalents [Member]
Assets Fair Value Disclosure
Assets Fair Value Disclosure	200,433	44,416
Level 1 [Member]
Assets Fair Value Disclosure
Assets Fair Value Disclosure	200,433	44,416
Level 1 [Member] | Money Market Funds [Member] | Cash Equivalents [Member]
Assets Fair Value Disclosure
Assets Fair Value Disclosure	$ 200,433	$ 44,416