Employees
| Concept | As at 2024-03-31 | As at 2024-03-31 | As at 2024-03-31 | As at 2024-03-31 | As at 2024-03-31 | As at 2024-03-31 | 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 | As at 2020-03-31 | As at 2020-03-31 | 
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Employees | ||||||||||||||||
| Information about group | ||||||||||||||||
| Number of employees of group | ||||||||||||||||
| Number of employees | 
                                                481
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                944
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                993
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                23
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                26
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                8
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                26
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                447
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                468
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                945
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                449
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                904
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                856
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                451
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                448
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                837
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
| Average number of temporary employees | 
                                                61
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                110
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                131
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                12
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                9
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                7
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                9
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                45
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                65
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                131
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                50
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                161
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                122
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                54
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                56
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                141
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             |