Fair Value Measurements - Summary of Fair Value of the Preferred Stock Tranche Rights Measured At Fair Value On a Recurring Basis Using Level 3 Significant Unobservable Inputs (Detail) - Recurring - Level 3 - Preferred Stock Tranche Rights $ in Thousands	9 Months Ended
	Sep. 30, 2021 USD ($)
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Balance at December 31, 2020	$ 318
Change in fair value	50
Balance at September 30, 2021	0
Series A Preferred Stock
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Fair value recognized as Series A-1 Preferred Stock upon settlement of Preferred Stock Tranche Rights	$ (368)