v3.26.1
Discontinued operations and assets held for sale - Transfer of Jyseleca Business to Alfasigma (Details) - Jyseleca business, classified as held for sale
12 Months Ended
Dec. 30, 2023
item
Oct. 30, 2023
country
Dec. 31, 2025
EUR (€)
Dec. 31, 2024
EUR (€)
Disclosure of analysis of single amount of off-balance sheet arrangements [line items]        
Number of positions in European countries agreed to transfer | item 400      
Number of European countries in which positions has been agreed to transfer | country   14    
Upfront payment received       € 50,000,000
Potential Sales Based Milestones To Receive.       120,000,000
Contributions related to development activities.     € 25,000,000 € 15,000,000