v3.26.1
Summary of significant transactions - Strategic Reorganization And Wind Down Of The Cell Therapy Activities (Details)
 12 Months Ended
Oct. 21, 2025
employee
Jan. 08, 2025
employee
Dec. 31, 2025
EUR (€)
entity
Dec. 31, 2024
EUR (€)
Dec. 31, 2023
EUR (€)
Summary Of Significant Transaction [line items]          
Number Of Publicly Trade Entities Traded | entity     2    
Impairment of fixed assets     € 228,112,000    
Other operating expense     53,493,000 € 40,773,000 € 47,272,000
Deferred tax income     19,413,000 € 3,104,000 € (3,685,000)
provision for early termination of collobaration     16,300,000    
Former owners of cell point          
Summary Of Significant Transaction [line items]          
Gain On Fair Value adjustment on the contingent consideration payable.     21,800,000    
Cell Point and AbountBio [Member]          
Summary Of Significant Transaction [line items]          
Deferred tax income     19,300,000    
Small molecules activities          
Summary Of Significant Transaction [line items]          
Number Of Reduction In Positions | employee   300      
Percentage of reduction in employees across Belgium and France   40.00%      
Cost for strategic reorganization and separation     124,800,000    
Severance costs     47,700,000    
Cost for early termination of collaborations     46,100,000    
Impairment of fixed assets     9,500,000    
Deal Cost     14,800,000    
Accelerated non cash cost recognition for subscription right     4,600,000    
Other operating expense     2,100,000    
Cell Therapy Business Associated Assets [member]          
Summary Of Significant Transaction [line items]          
Number Of Reduction In Positions | employee 365        
Severance costs     33,300,000    
Impairment of fixed assets     228,100,000    
Deal Cost     10,100,000    
Accelerated non cash cost recognition for subscription right     1,500,000    
Other operating expense     7,500,000    
Total Pre Tax Effect Of Winddown     € 275,000,000