v3.26.1
Intangible assets - Schedule of reconciliation of intangible assets (Details) - EUR (€)
€ in Thousands
 12 Months Ended
Dec. 31, 2025
Dec. 31, 2024
Disclosure of detailed information about intangible assets [line items]    
Intangible assets other than goodwill, beginning balance € 25,258 € 25,567
Additions 61 2,579
Amortization charge (2,904) (2,958)
Impairment charge (3) 0
Exchange rate differences (64) 71
Intangible assets other than goodwill, ending balance 22,349 25,258
Cost    
Disclosure of detailed information about intangible assets [line items]    
Intangible assets other than goodwill, beginning balance 96,516  
Intangible assets other than goodwill, ending balance 96,187 96,516
Accumulated amortization and impairment    
Disclosure of detailed information about intangible assets [line items]    
Intangible assets other than goodwill, beginning balance (71,258)  
Intangible assets other than goodwill, ending balance (73,838) (71,258)
Software    
Disclosure of detailed information about intangible assets [line items]    
Intangible assets other than goodwill, beginning balance 205 255
Additions 61 79
Amortization charge (82) (126)
Impairment charge (3) 0
Exchange rate differences 4 (2)
Intangible assets other than goodwill, ending balance 186 205
Software | Cost    
Disclosure of detailed information about intangible assets [line items]    
Intangible assets other than goodwill, beginning balance 5,823  
Intangible assets other than goodwill, ending balance 5,861 5,823
Software | Accumulated amortization and impairment    
Disclosure of detailed information about intangible assets [line items]    
Intangible assets other than goodwill, beginning balance (5,618)  
Intangible assets other than goodwill, ending balance (5,676) (5,618)
Acquired R&D technology and projects    
Disclosure of detailed information about intangible assets [line items]    
Intangible assets other than goodwill, beginning balance 23,948 24,073
Additions 0 2,500
Amortization charge (2,685) (2,687)
Impairment charge 0 0
Exchange rate differences (58) 62
Intangible assets other than goodwill, ending balance 21,206 23,948
Acquired R&D technology and projects | Cost    
Disclosure of detailed information about intangible assets [line items]    
Intangible assets other than goodwill, beginning balance 83,349  
Intangible assets other than goodwill, ending balance 83,012 83,349
Acquired R&D technology and projects | Accumulated amortization and impairment    
Disclosure of detailed information about intangible assets [line items]    
Intangible assets other than goodwill, beginning balance (59,400)  
Intangible assets other than goodwill, ending balance (61,806) (59,400)
Development costs    
Disclosure of detailed information about intangible assets [line items]    
Intangible assets other than goodwill, beginning balance 1,104 1,239
Additions 0 0
Amortization charge (137) (145)
Impairment charge 0 0
Exchange rate differences (10) 11
Intangible assets other than goodwill, ending balance 957 1,104
Development costs | Cost    
Disclosure of detailed information about intangible assets [line items]    
Intangible assets other than goodwill, beginning balance 7,345  
Intangible assets other than goodwill, ending balance 7,313 7,345
Development costs | Accumulated amortization and impairment    
Disclosure of detailed information about intangible assets [line items]    
Intangible assets other than goodwill, beginning balance (6,240)  
Intangible assets other than goodwill, ending balance (6,356) (6,240)
Intangible assets in the course of construction    
Disclosure of detailed information about intangible assets [line items]    
Intangible assets other than goodwill, beginning balance 0 0
Additions 0 0
Amortization charge 0 0
Impairment charge 0 0
Exchange rate differences 0 0
Intangible assets other than goodwill, ending balance 0 0
Intangible assets in the course of construction | Cost    
Disclosure of detailed information about intangible assets [line items]    
Intangible assets other than goodwill, beginning balance 0  
Intangible assets other than goodwill, ending balance 0 0
Intangible assets in the course of construction | Accumulated amortization and impairment    
Disclosure of detailed information about intangible assets [line items]    
Intangible assets other than goodwill, beginning balance 0  
Intangible assets other than goodwill, ending balance € 0 € 0