Other current liabilities - Schedule of Other Current Liabilities (Details) - USD ($) $ in Thousands	Sep. 30, 2021	Dec. 31, 2020
Other current liabilities
Payroll	$ 18,926	$ 13,694
Accrued professional service fee	3,607	3,128
Payables for purchase of property and equipment	1,797	788
Accrued rebate to distributors	10,803	7,067
Tax payable	10,989	952
Others	8,170	4,567
Total	$ 54,292	$ 30,196