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Summary of Significant Accounting Policies - Summary of reconciliation of cash and cash equivalents and restricted cash reported within the condensed balance sheets (Detail) - USD ($)
$ in Thousands
Mar. 31, 2021
Dec. 31, 2020
Mar. 31, 2020
Dec. 31, 2019
Cash and cash equivalents $ 374,205 $ 386,569    
Restricted cash 350 350    
Total cash and cash equivalents and restricted cash 374,555 386,919 $ 24,180 $ 10,526
Restricted Cash [Member]        
Cash and cash equivalents 374,205 386,569    
Restricted cash 350 350    
Total cash and cash equivalents and restricted cash $ 374,555 $ 386,919