v3.25.4
Property, plant and equipment - Addtional information (Detail) - EUR (€)
€ in Millions
12 Months Ended
Dec. 31, 2025
Dec. 31, 2024
Disclosure of detailed information about property, plant and equipment [line items]    
Unpaid investment decreased € 0.5 € 0.8
Property, Plant and Equipment [Member]    
Disclosure of detailed information about property, plant and equipment [line items]    
Non cash investments 0.5 0.8
Office Equipment And Installations [Member]    
Disclosure of detailed information about property, plant and equipment [line items]    
Additions Property Plant And Equipment 5.0 8.7
Construction [Member]    
Disclosure of detailed information about property, plant and equipment [line items]    
Additions Property Plant And Equipment € 0.6 € 0.0