Significant agreements - Novartis Collaboration Agreement (Details) $ in Thousands		6 Months Ended
	Mar. 27, 2023 USD ($) item	Jun. 30, 2023
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Maximum Days Allowed for Cancellation of Contracts Prior Written Notice		90 days
Termination In Entirety Or Product By Product Or Target By Target Basis [Member]
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Threshold period of notice required for termination of agreement	90 days
Completion of All Milestones For Targets [Member]
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Milestone payments receivable	$ 800,000
Novartis Collaboration Agreement
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Number of collaboration targets | item	2
Additional research term	1 year
Upfront cash payment	$ 50,000
Milestone payments receivable	210,000
Milestone payments, receivable	$ 840,000
Maximum Days Allowed for Cancellation of Contracts Prior Written Notice	30 days
Total transaction price initially determined	$ 50,000
Expected period for satisfaction of performance obligations	3 years
Material rights exercise period	6 years
Novartis Collaboration Agreement | Termination Based On Other Party's Uncured Material Breach Or Insolvency [Member]
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Threshold period of notice required for termination of agreement	60 days
Novartis Collaboration Agreement | Termination If Safety Or Regulatory Issue Exists [Member]
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Threshold period of notice required for termination of agreement	30 days
Novartis Collaboration Agreement | Achievement of Specified Levels of Net Sales [Member]
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Milestone payments receivable	$ 200,000