Significant agreements - Novartis Collaboration Agreement (Details) $ in Thousands		3 Months Ended		9 Months Ended
	Mar. 27, 2023 USD ($) item	Sep. 30, 2023 USD ($)	Sep. 30, 2022 USD ($)	Sep. 30, 2023 USD ($)	Sep. 30, 2022 USD ($)
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Maximum days allowed for cancellation of contracts prior written notice				90 days
Revenue from collaborative arrangement		$ 5,352	$ 3,040	$ 21,645	$ 11,278
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
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
Revenue from collaborative arrangement		$ 772	$ 0	$ 772	$ 0
Novartis | 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 | 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 | Achievement of Specified Levels of Net Sales [Member]
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Milestone payments receivable	$ 200,000