Stock-based compensation - Compensation expense (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2024	Sep. 30, 2023
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation	$ 3,434	$ 2,878	$ 11,048	$ 8,108
Employee Stock Option [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation	2,373	2,021	7,357	5,587
Restricted stock awards and units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation	983	774	3,454	2,339
Employee stock purchase plan awards
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation	78	83	237	182
Research and development
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation	1,590	919	4,495	2,472
General and administrative
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation	$ 1,844	$ 1,959	$ 6,553	$ 5,636