Employees
| Concept | As at 2024-05-31 | As at 2024-05-31 | As at 2023-05-31 | As at 2023-05-31 | As at 2022-05-31 | As at 2022-05-31 | As at 2021-05-31 | As at 2021-05-31 | As at 2020-05-31 | As at 2020-05-31 | 
|---|---|---|---|---|---|---|---|---|---|---|
| Employees | ||||||||||
| Information about group | ||||||||||
| Number of employees of group | ||||||||||
| Number of employees | 
                                                1,006
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                1,152
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                1,138
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                994
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                973
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                1,120
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                952
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                1,101
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                908
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                1,049
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
| Average number of temporary employees | 
                                                89
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                89
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                85
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                84
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                87
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                88
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                82
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                84
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                90
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                94
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             |