Significant agreements - Ionis Evaluation and Option Agreement (Details) - USD ($) $ in Thousands		1 Months Ended	6 Months Ended	12 Months Ended
	Jul. 09, 2021	Jan. 31, 2021	Jun. 30, 2023	Dec. 31, 2020	Dec. 31, 2022	Dec. 31, 2021
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Deferred revenue			$ 144,837		$ 61,873	$ 71,340
Ionis Evaluation and Option Agreement
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Term of the Evaluation Period (in months)				4 months
Upfront cash payment	$ 3,000	$ 3,000	$ 3,000	$ 3,000
Threshold period of notice required for termination of agreement			30 days
Deferred revenue				$ 3,000	$ 21,500