Stockholders'/Members' Equity (Deficit) - Schedule of Stock-based Compensation Expense (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Class Of Stock [Line Items]
Stock-based compensation	$ 4,366	$ 0	$ 21,307	$ 0
Research and Development Expense
Class Of Stock [Line Items]
Stock-based compensation	1,267		3,376
General and Administrative Expense
Class Of Stock [Line Items]
Stock-based compensation	$ 3,099		$ 17,931