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Summary of Significant Accounting Policies - Schedule of Cash, Cash Equivalents, and Restricted Cash (Detail) - USD ($)
$ in Thousands
Sep. 30, 2021
Dec. 31, 2020
Sep. 30, 2020
Dec. 31, 2019
Accounting Policies [Abstract]        
Cash and cash equivalents $ 459,288 $ 1,309    
Restricted cash 490 565    
Total cash, cash equivalents, and restricted cash $ 459,778 $ 1,874 $ 988 $ 3,612