Share-based compensation - Costs (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2025	Sep. 30, 2024	Sep. 30, 2025	Sep. 30, 2024
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total share-based compensation expense	$ 6,747	$ 4,892	$ 17,797	$ 10,278
Unrecognized compensation cost	87,400		$ 87,400
Recognition period			3 years 1 month 6 days
Research and development
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total share-based compensation expense	2,851	1,820	$ 7,518	3,244
General and administrative
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total share-based compensation expense	$ 3,896	$ 3,072	$ 10,279	$ 7,034