Subclassifications Of Assets, Liabilities And Equities [Abstract]
| Concept | As at 2024-12-31 | As at 2023-12-31 | As at 2022-12-31 | 
|---|---|---|---|
| Subclassifications of assets, liabilities and equities [abstract] | |||
| Property, plant and equipment [abstract] | |||
| Property, plant and equipment | 
                                                132,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | 
                                                245,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | 
                                                434,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | 
| Intangible assets and goodwill [abstract] | |||
| Intangible assets other than goodwill [abstract] | |||
| Intangible assets other than goodwill | 
                                                2,537,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | 
                                                3,247,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | 
                                                3,946,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | 
| Goodwill | 
                                                1,213,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | 
                                                1,213,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | 
                                                1,213,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | 
| Trade and other current receivables [abstract] | |||
| Trade and other current receivables | 
                                                279,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | 
                                                1,342,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | 
                                                1,294,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | 
| Cash and cash equivalents [abstract] | |||
| Cash and cash equivalents | 
                                                2,672,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | 
                                                2,669,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | 
                                                3,378,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | 
| Trade and other current payables [abstract] | |||
| Trade and other current payables | 
                                                319,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | 
                                                1,395,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | 
                                                1,460,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | 
| Issued capital [abstract] | |||
| Issued capital | 
                                                2,354,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | 
                                                2,354,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | 
                                                2,354,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | 
| Retained earnings [abstract] | |||
| Retained earnings | 
                                                32,890,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | 
                                                32,087,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | 
                                                30,609,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | 
| Net assets (liabilities) [abstract] | |||
| Assets | 
                                                8,134,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | 
                                                9,660,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | 
                                                11,012,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | 
| Net current assets (liabilities) [abstract] | |||
| Current assets | 
                                                4,252,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | 
                                                4,955,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | 
                                                5,419,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | 
| Current liabilities | 
                                                1,613,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | 
                                                2,336,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | 
                                                2,210,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | 
| Assets less current liabilities [abstract] |