Significant agreements - Novartis Collaboration Agreement - Accounting Analysis (Details) $ in Thousands	Mar. 27, 2023 USD ($) item
Two Combined Performance Obligations For First And Second Targets [Member]
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Combined performance obligations | item	2
Two Material Rights Associated With Limited Substitution Rights [Member]
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Combined performance obligations | item	2
Two Material Rights Associated With Options To Progress Development Candidates Incorporating Radionuclides [Member]
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Combined performance obligations | item	2
Two Material Rights Associated With Options To Progress Development Candidates Not Incorporating Radionuclides [Member]
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Combined performance obligations | item	2
Novartis Collaboration Agreement
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Transaction price	$ 50,000
Novartis Collaboration Agreement | Two Combined Performance Obligations For First And Second Targets [Member]
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Transaction price	18,008
Novartis Collaboration Agreement | Two Material Rights Associated With Limited Substitution Rights [Member]
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Transaction price	2,466
Novartis Collaboration Agreement | Two Material Rights Associated With Options To Progress Development Candidates Incorporating Radionuclides [Member]
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Transaction price	19,684
Novartis Collaboration Agreement | Two Material Rights Associated With Options To Progress Development Candidates Not Incorporating Radionuclides [Member]
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Transaction price	$ 9,842