Share-based compensation - Restricted Share Units (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022
Restricted shares
Total share-based compensation expense	$ 8,193	$ 5,673	$ 17,235	$ 15,871
Restricted ordinary shares | 2020 Plan
Number of Shares Underlying RSUs
Unvested restricted ordinary shares at beginning			187,725
Granted			321,839
Vested			(78,781)
Forfeited			(27,813)
Unvested restricted ordinary shares at ending	402,970		402,970
Weighted Average Grant Date Fair Value
Weighted average grant date fair value unvested, Beginning Balance			$ 60.86
Granted			29.59
Vested			52.87
Forfeited			41.18
Weighted average grant date fair value unvested, Ending Balance	$ 38.81		$ 38.81
Restricted shares
Fair value of employee restricted share awards vested	$ 500	0	$ 2,100	2,100
Total share-based compensation expense	1,400	$ 700	3,000	$ 3,500
Unrecognized compensation cost	$ 13,900		$ 13,900
Weighted average Period			2 years 10 months 24 days