Significant agreements - Ionis Evaluation and Option Agreement (Details) - USD ($) $ in Thousands		12 Months Ended
	Jul. 09, 2021	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Collaboration revenues		$ 11,697	$ 10,390	$ 13,801
Deferred revenue		$ 71,340	$ 35,156	$ 5,657
Ionis Evaluation and Option Agreement
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Term, Bicycle Research Term (in months)			4 months
Threshold period for receipt of revenue after receipt of the materials and related data package			5 days
Threshold period of notice required for termination of agreement		30 days
Upfront cash payment	$ 3,000	$ 3,000	$ 3,000
Collaboration revenues			3,000
Deferred revenue			$ 3,000