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Income taxes - Schedule of change in total valuation allowance for deferred tax assets (Detail) - USD ($)
$ in Thousands
12 Months Ended
Dec. 31, 2022
Dec. 31, 2021
Dec. 31, 2020
Income Tax Disclosure [Abstract]      
Opening valuation allowance $ 212,192 $ 206,011 $ 62,628
Reduction during the year (214) (1,206) (35,662)
Addition during the year 10,677 7,387 179,045
Closing valuation allowance $ 222,655 $ 212,192 $ 206,011