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Short-term investments - Additional Information (Detail) - USD ($)
3 Months Ended 6 Months Ended
Jun. 30, 2022
Jun. 30, 2022
Dec. 31, 2021
Debt Securities, Available-for-Sale [Line Items]      
Debt securities, available-for-sale, unrealized loss $ 2,430,000 $ 2,430,000  
Short-term investments     $ 0
Short-Term Investments [Member]      
Debt Securities, Available-for-Sale [Line Items]      
Proceeds from sale of debt securities, available-for-Sale   0  
Payments to acquire debt securities, available-for-Sale   196,800,000  
Debt securities, available-for-sale, unrealized loss $ 2,400,000 $ 2,429,000