v3.26.1
Related parties - Narrative (Details)
 12 Months Ended
Dec. 31, 2025
EUR (€)
item
Dec. 31, 2024
EUR (€)
Dec. 31, 2023
EUR (€)
item
Dec. 31, 2019
Nov. 06, 2019
Aug. 28, 2019
Disclosure of amounts incurred by entity for provision of key management personnel services provided by separate management entities [line items]            
Deferred income other than contract liabilities € 32,000 € 1,071,352,000 € 1,327,463,000      
Gilead [member]            
Disclosure of amounts incurred by entity for provision of key management personnel services provided by separate management entities [line items]            
Percentage of ownership interest 25.35%     25.84% 25.10% 22.04%
Number of Directors Represented as Board of Directors | item 2          
Minimum Percentage Of Ownership Required To Appoint Investor Board Designees 20.00%          
Number of performance obligations | item     2      
Gilead collaboration agreement for drug discovery platform | Gilead [member]            
Disclosure of amounts incurred by entity for provision of key management personnel services provided by separate management entities [line items]            
Deferred income other than contract liabilities   1,068,981,000 € 1,299,163,000      
Collaboration agreement for filgotinib | Gilead [member]            
Disclosure of amounts incurred by entity for provision of key management personnel services provided by separate management entities [line items]            
Deferred income other than contract liabilities     € 26,268,000      
Deferred income released   € 26,300,000