Employees
| Concept | 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 | As at 2020-03-31 | As at 2020-03-31 | 
|---|---|---|---|---|---|---|---|---|---|---|
| Employees | ||||||||||
| Information about group | ||||||||||
| Number of employees of group | ||||||||||
| Number of employees | 
                                                80
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                1,384
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                1,370
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                80
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                71
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                1,402
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                1,438
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                69
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                64
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                1,448
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
| Average number of temporary employees | 
                                                0
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                4,768
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                4,640
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                8
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                10
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                4,027
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                4,290
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                9
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                6
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                5,065
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             |