v3.26.1
Revenue and government financing for research expenditures - Disclosure of Variance of Deferred Revenue (Details) - EUR (€)
€ in Thousands
 12 Months Ended
Dec. 31, 2025
Dec. 31, 2024
Dec. 31, 2023
Disclosure of disaggregation of revenue from contracts with customers [line items]      
Deferred revenue – current portion € 2,825 € 616 € 5,865
Deferred revenue – non-current portion 0 2,825 4,618
Deferred tax liabilities / Deferred revenue      
Disclosure of disaggregation of revenue from contracts with customers [line items]      
Contract liabilities at beginning of period 3,441 10,483 14,481
Recognition in P&L (620) (6,504) (12,373)
Proceeds 0 0 8,200
Transfer from collaboration liabilities 5 (536) 173
Contract liabilities at end of period 2,826 3,441 10,483
Deferred tax liabilities / Deferred revenue | Monalizumab      
Disclosure of disaggregation of revenue from contracts with customers [line items]      
Contract liabilities at beginning of period 215 5,155 14,481
Recognition in P&L (220) (4,404) (9,499)
Proceeds 0 0 0
Transfer from collaboration liabilities 5 (536) 173
Contract liabilities at end of period 0 215 5,155
Deferred tax liabilities / Deferred revenue | Sanofi services      
Disclosure of disaggregation of revenue from contracts with customers [line items]      
Contract liabilities at beginning of period 726 2,826 0
Recognition in P&L (400) (2,100) (374)
Proceeds 0 0 3,200
Transfer from collaboration liabilities 0 0 0
Contract liabilities at end of period 326 726 2,826
Deferred tax liabilities / Deferred revenue | Sanofi options      
Disclosure of disaggregation of revenue from contracts with customers [line items]      
Contract liabilities at beginning of period 2,500 2,500 0
Recognition in P&L 0 0 (2,500)
Proceeds 0 0 5,000
Transfer from collaboration liabilities 0 0 0
Contract liabilities at end of period 2,500 2,500 2,500
Deferred tax liabilities / Deferred revenue | Others      
Disclosure of disaggregation of revenue from contracts with customers [line items]      
Contract liabilities at beginning of period € 0 0  
Recognition in P&L   0  
Proceeds   0  
Transfer from collaboration liabilities   0  
Contract liabilities at end of period   € 0 € 0