Stock-based compensation - Stock Based Compensation Expense (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Stock options
Stock-based compensation expense included in total operating expenses	$ 21,522	$ 18,409	$ 7,172
Stock options
Stock options
Stock-based compensation expense included in total operating expenses	15,814	14,528	5,725
Unvested restricted stock units
Stock options
Stock-based compensation expense included in total operating expenses	5,175	3,522	1,187
Employee stock purchase plan
Stock options
Stock-based compensation expense included in total operating expenses	533	359	260
Research and development
Stock options
Stock-based compensation expense included in total operating expenses	11,386	9,984	3,841
General and administrative
Stock options
Stock-based compensation expense included in total operating expenses	$ 10,136	$ 8,425	$ 3,331