v3.26.1
Share capital and share based payments - Additional Information (Details)
12 Months Ended
Jan. 02, 2024
Dec. 31, 2023
EUR (€)
employee
€ / shares
shares
Nov. 07, 2022
shares
Dec. 31, 2025
EUR (€)
shares
subsidiary
action
€ / shares
Dec. 31, 2024
EUR (€)
shares
condition
€ / shares
Dec. 31, 2023
EUR (€)
shares
vestingKicker
€ / shares
Dec. 31, 2022
filingsAndApproval
vestingKicker
€ / shares
shares
Dec. 31, 2021
vestingKicker
Dec. 31, 2020
vestingKicker
Apr. 24, 2025
EUR (€)
Jan. 27, 2025
clinicalProductCandidate
Disclosure of changes in the share capital                      
Share capital   € 4,044,000   € 4,686,661 € 4,192,000 € 4,044,000       € 4,609,489.9  
Par value per share (in EUR per share) | € / shares   € 0.05   € 0.05 € 0.05 € 0.05 € 0.05        
Number of own shares (in shares) | shares       18,575              
Expense from share-based payment transactions with employees       € 2,567,000 € 3,944,000 € 4,256,000          
Number of filing and approval of a biologic license application | filingsAndApproval             1        
Number of patients planned to be enrolled in medical study | clinicalProductCandidate                     105
Number of subsidiaries | subsidiary       1              
AGA Perf Management 2019-1                      
Disclosure of changes in the share capital                      
Performance conditions threshold     50.00%                
Number of other equity instruments exercised or vested in share-based payment arrangement (in shares) | shares     171,550                
AGA Bonus 2022-1 [Member]                      
Disclosure of changes in the share capital                      
Number of other equity instruments exercised or vested in share-based payment arrangement (in shares) | shares       128,061 128,061 128,061          
Expense from share-based payment transactions with employees       € 0 € 0 € 0          
Percentge of annual variable compensation       50.00%              
Percentage of premium increased       50.00%              
Percentage of over performance       1              
AGA Perf Employees 2020-1 / AGA Perf Management 2020                      
Disclosure of changes in the share capital                      
Number of vesting kickers | vestingKicker                 2    
Revenue from collaboration and licensing agreements, minimum accrual between attribution and definitive acquisition date       € 100,000,000              
AGA Perf Management 2020-1                      
Disclosure of changes in the share capital                      
Number of other equity instruments exercised or vested in share-based payment arrangement (in shares)   130,000   130,000 130,000 130,000          
AGAP Employee 2020 / AGAP Management 2020                      
Disclosure of changes in the share capital                      
Expense from share-based payment transactions with employees       € 0 € 0 € 1,436,000          
Free performances shares plans, performance (in percents) 20.00%                    
AGA Perf Employees 2020-1                      
Disclosure of changes in the share capital                      
Number of other equity instruments exercised or vested in share-based payment arrangement (in shares)   85,230   85,230 85,230 85,230          
AGA Perf Employees 2019 / AGA Perf Management 2019 [Member]                      
Disclosure of changes in the share capital                      
Expense from share-based payment transactions with employees       € 0 € 0            
AGAP Employee 2021 / AGAP Management 2021                      
Disclosure of changes in the share capital                      
Expense from share-based payment transactions with employees       0 1,162,000 € 1,161,000          
Number of vesting kickers | vestingKicker               2      
AGAP Employee 2023/ AGAP Management 2023                      
Disclosure of changes in the share capital                      
Expense from share-based payment transactions with employees       702,000 1,226,000 € 33,000          
Number of vesting kickers | vestingKicker           3          
Revenue from collaboration and licensing agreements, minimum accrual between attribution and definitive acquisition date       € 50,000,000              
Implementation of environmental or social actions by employees | action       6              
AGAP Employee 2022 / AGAP Management 2022                      
Disclosure of changes in the share capital                      
Expense from share-based payment transactions with employees       € 891,000 € 888,000 € 1,157,000          
Number of vesting kickers | vestingKicker             3        
AGA New Members 2023-1                      
Disclosure of changes in the share capital                      
Number of other equity instruments exercised or vested in share-based payment arrangement (in shares) | shares       0 0 0          
Expense from share-based payment transactions with employees       € 19,000 € 19,000 € 3,000          
AGA New Members 2024-1                      
Disclosure of changes in the share capital                      
Number of other equity instruments exercised or vested in share-based payment arrangement (in shares) | shares       0 0            
Expense from share-based payment transactions with employees       € (17,000) € 17,000 0          
AGA Perf Management 2024-1                      
Disclosure of changes in the share capital                      
Number of other equity instruments exercised or vested in share-based payment arrangement (in shares) | shares       0 0            
Expense from share-based payment transactions with employees       € 0 € 302,000 0          
Number of internal conditions performance, free performance shares | condition         2            
Other free shares                      
Disclosure of changes in the share capital                      
Expense from share-based payment transactions with employees       231,000 € 32,000 0          
AGAP Employee 2024/ AGAP Management 2024                      
Disclosure of changes in the share capital                      
Expense from share-based payment transactions with employees       699,000 € 119,000 0          
Revenue from collaboration and licensing agreements, minimum accrual between attribution and definitive acquisition date       € 50,000,000              
Number of internal conditions performance, free performance shares | condition         3            
Percent of employees using transport mobility       25.00%              
AGA Employee 2025                      
Disclosure of changes in the share capital                      
Expense from share-based payment transactions with employees       € 54,000 € 0 € 0          
BSAAR                      
Disclosure of changes in the share capital                      
Number of other equity instruments exercised or vested in share-based payment arrangement (in shares) | shares       0 0 47,100          
Share-based payment transactions with employees, awards, expected term (year)       10 years              
Common shares                      
Disclosure of changes in the share capital                      
Number of shares outstanding (in shares) | shares   80,860,563   93,719,323 83,830,336 80,860,563 80,212,069        
Par value per share (in EUR per share) | € / shares       € 0.05              
2016 free preferred shares                      
Disclosure of changes in the share capital                      
Number of shares outstanding (in shares) | shares       6,324              
Par value per share (in EUR per share) | € / shares       € 0.05              
2017 free preferred shares                      
Disclosure of changes in the share capital                      
Number of shares outstanding (in shares) | shares       7,581              
Par value per share (in EUR per share) | € / shares       € 0.05