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Balance Sheet Components - Summary of Gross Unrealized Gains and Unrealized Losses of Investment Securities Excluding Investments in Money Market Funds (Parenthetical) (Detail) - USD ($)
$ in Thousands
Sep. 30, 2021
Dec. 31, 2020
Schedule of Available-for-sale Securities [Line Items]    
Cash and cash equivalents $ 80,885 $ 44,597
Commercial Paper [Member]    
Schedule of Available-for-sale Securities [Line Items]    
Cash and cash equivalents $ 42,200