Subclassifications Of Assets, Liabilities And Equities [Abstract]
| Concept | As at 2024-09-30 | As at 2023-09-30 | As at 2023-09-30 | As at 2022-09-30 | 
|---|---|---|---|---|
| Subclassifications of assets, liabilities and equities [abstract] | ||||
| Property, plant and equipment [abstract] | ||||
| Property, plant and equipment | 
                                                1,518
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | — | 
                                                2,048
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | — | 
| Intangible assets and goodwill [abstract] | ||||
| Intangible assets other than goodwill [abstract] | ||||
| Intangible assets other than goodwill | 
                                                7,850
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | — | 
                                                9,689
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | — | 
| Goodwill | 
                                                52,303
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | — | 
                                                69,266
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | — | 
| Trade and other current receivables [abstract] | ||||
| Trade and other current receivables | 
                                                21,409
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | — | 
                                                29,084
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | — | 
| Cash and cash equivalents [abstract] | ||||
| Cash [abstract] | ||||
| Balances with banks | 
                                                12,080
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | — | 
                                                6,900
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | — | 
| Cash and cash equivalents | 
                                                12,080
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | — | 
                                                6,900
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | 
                                                6,058
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | 
| Trade and other current payables [abstract] | ||||
| Trade and other current payables | 
                                                6,935
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | — | 
                                                9,647
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | — | 
| Issued capital [abstract] | ||||
| Issued capital | 
                                                41,153
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | — | 
                                                37,412
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | — | 
| Retained earnings [abstract] | ||||
| Retained earnings | 
                                                14,987
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | 
                                                663,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | 
                                                38,358
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | — | 
| Accumulated other comprehensive income [abstract] | ||||
| Accumulated other comprehensive income | 
                                                478,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | — | 
                                                440,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | — | 
| Miscellaneous equity [abstract] | ||||
| Additional paid-in capital | 
                                                8,884
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | — | 
                                                9,689
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | — | 
| Net assets (liabilities) [abstract] | ||||
| Assets | 
                                                127,604
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | — | 
                                                162,736
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | — | 
| Liabilities | 
                                                79,207
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | — | 
                                                95,551
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | — | 
| Net current assets (liabilities) [abstract] | ||||
| Current assets | 
                                                39,856
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | — | 
                                                50,715
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | — | 
| Current liabilities | 
                                                60,808
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | — | 
                                                70,331
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | — | 
| Assets less current liabilities [abstract] |