Stock-based compensation - Stock Based Compensation Expense by Award Type (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022
Stock options
Stock-based compensation expense included in total operating expenses	$ 6,643	$ 5,348	$ 13,050	$ 10,833
Stock options
Stock options
Stock-based compensation expense included in total operating expenses	4,288	3,933	8,507	8,051
Restricted stock units
Stock options
Stock-based compensation expense included in total operating expenses	2,060	1,258	3,953	2,467
Employee stock purchase plan
Stock options
Stock-based compensation expense included in total operating expenses	$ 295	$ 157	$ 590	$ 315