Share-based compensation - Restricted Share Units (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Restricted shares
Total share-based compensation expense	$ 32,477	$ 26,779	$ 12,083
Restricted ordinary shares | 2020 Plan
Number of Shares Underlying RSUs
Unvested restricted ordinary shares at beginning	187,725
Granted	333,089
Vested	(119,144)
Forfeited	(74,822)
Unvested restricted ordinary shares at ending	326,848	187,725
Weighted Average Grant Date Fair Value
Weighted average grant date fair value unvested, Beginning Balance	$ 60.86
Granted	29.27
Vested	50.30
Forfeited	39.55
Weighted average grant date fair value unvested, Ending Balance	$ 37.40	$ 60.86
Restricted shares
Fair value of employee restricted share awards vested	$ 3,000	$ 2,100	0
Total share-based compensation expense	5,500	$ 4,900	$ 0
Unrecognized compensation cost	$ 10,000
Weighted average Period	2 years 7 months 6 days