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Cash, Cash Equivalents and Marketable Securities - Additional Information (Detail)
9 Months Ended 12 Months Ended
Sep. 30, 2021
Dec. 31, 2020
Cash And Cash Equivalents [Line Items]    
Weighted average maturity period of available-for-sale securities   2 months
Maximum [Member]    
Cash And Cash Equivalents [Line Items]    
Weighted average maturity period of available-for-sale securities 1 month