Share-based compensation - Costs (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2024	Jun. 30, 2023	Jun. 30, 2024	Jun. 30, 2023
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense	$ 3,227	$ 1,033	$ 5,386	$ 2,257
Unrecognized compensation cost	43,700		$ 43,700
Recognition period			1 year 9 months 18 days
Research and development
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense	1,041	427	$ 1,424	857
General and administrative
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense	$ 2,186	$ 606	$ 3,962	$ 1,400