Stock-based compensation - Stock Based Compensation Expense (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Stock options
Stock-based compensation expense included in total operating expenses	$ 16,458	$ 21,136	$ 21,522
Research and development
Stock options
Stock-based compensation expense included in total operating expenses	8,889	11,043	11,386
General and administrative
Stock options
Stock-based compensation expense included in total operating expenses	7,569	10,093	10,136
Stock options
Stock options
Stock-based compensation expense included in total operating expenses	9,428	14,171	15,814
Restricted stock units and other stock awards
Stock options
Stock-based compensation expense included in total operating expenses	6,656	6,184	5,175
Employee stock purchase plan
Stock options
Stock-based compensation expense included in total operating expenses	$ 374	$ 781	$ 533