Employees
| Concept | As at 2025-03-31 | As at 2025-03-31 | As at 2024-03-31 | As at 2024-03-31 | As at 2023-03-31 | As at 2023-03-31 | As at 2022-03-31 | As at 2022-03-31 | As at 2021-03-31 | As at 2021-03-31 | 
|---|---|---|---|---|---|---|---|---|---|---|
| Employees | ||||||||||
| Information about group | ||||||||||
| Number of employees of group | ||||||||||
| Number of employees | 
                                                258
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                257
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                251
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                252
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                258
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                257
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                306
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                307
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                346
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                345
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
| Average number of temporary employees | 
                                                2,300
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                2,300
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                2,158
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                2,158
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                2,212
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                2,212
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                1,835
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                1,835
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                2,250
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                2,250
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             |