Share-based compensation - Restricted Share Units (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Restricted shares
Total share-based compensation expense	$ 9,282	$ 9,042
Restricted share units | 2020 Plan
Number of Shares Underlying RSUs
Unvested restricted ordinary shares at beginning	326,848
Granted	596,996
Vested and settled	(67,096)
Vested and deferred	(10,500)
Unvested restricted ordinary shares at ending	846,248
Unvested restricted ordinary shares, Vested but subject to deferred settlement	10,500
Outstanding ordinary shares at ending	856,748
Weighted Average Grant Date Fair Value
Weighted average grant date fair value unvested, Beginning Balance	$ 37.40
Granted	18.12
Vested and settled	33.99
Vested and deferred	18.07
Weighted average grant date fair value unvested, Ending Balance	24.31
Weighted average grant date fair value, Vested but subject to deferred settlement	18.07
Weighted average grant date fair value unvested, Ending Balance	$ 24.23
Restricted shares
Fair value of employee restricted share awards vested	$ 1,500	1,600
Total share-based compensation expense	1,800	$ 1,600
Unrecognized compensation cost	$ 18,900
Weighted average Period	3 years