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Marketable Securities and Fair Value Measurements - Summary of marketable securities (Detail) - Fair Value, Recurring [Member] - USD ($)
$ in Thousands
Sep. 30, 2021
Dec. 31, 2020
Marketable Securities [Line Items]    
Amortized cost   $ 199,429
Gross unrealized gains   13
Gross unrealized losses   (4)
Fair value   199,438
U.S. treasury securities    
Marketable Securities [Line Items]    
Amortized cost $ 10,016 129,446
Gross unrealized gains   9
Gross unrealized losses   (4)
Fair value $ 10,016 129,451
Commercial paper    
Marketable Securities [Line Items]    
Amortized cost   52,441
Fair value   52,441
Corporate debt securities    
Marketable Securities [Line Items]    
Amortized cost   17,542
Gross unrealized gains   4
Fair value   $ 17,546