Significant agreements - Ionis Evaluation and Option Agreement (Details) - USD ($) $ in Thousands			1 Months Ended	12 Months Ended
	Jul. 09, 2021	Dec. 31, 2020	Jan. 31, 2021	Dec. 31, 2022	Dec. 31, 2020	Dec. 31, 2021
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Deferred revenue		$ 35,156		$ 61,873	$ 35,156	$ 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			$ 3,000