Employees
| Concept | 
                                    
                                        As at 2024-07-31  | 
                            
                                
                                    
                                        As at 2023-07-31  | 
                            
                                
                                    
                                        As at 2022-07-31  | 
                            
                                
                                    
                                        As at 2021-07-31  | 
                            
                                
                                    
                                        As at 2020-07-31  | 
                            
                        
|---|---|---|---|---|---|
| Employees | |||||
| Information about group | |||||
| Number of employees of group | |||||
| Number of employees | 
                                        
                                             
                                                267
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             
                                        
                                     | 
                                
                                    
                                        
                                             
                                                268
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             
                                        
                                     | 
                                
                                    
                                        
                                             
                                                223
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             
                                        
                                     | 
                                
                                    
                                        
                                             
                                                220
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             
                                        
                                     | 
                                
                                    
                                        
                                             
                                                236
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             
                                        
                                     |