Stock-based compensation - Stock Based Compensation Expense by Award Type (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2023	Mar. 31, 2022
Stock options
Stock-based compensation expense included in total operating expenses	$ 6,407	$ 5,485
Stock options
Stock options
Stock-based compensation expense included in total operating expenses	4,219	4,118
Restricted stock units
Stock options
Stock-based compensation expense included in total operating expenses	1,893	1,209
Employee stock purchase plan
Stock options
Stock-based compensation expense included in total operating expenses	$ 295	$ 158