Employees
| Concept | As at 2025-03-31 | As at 2025-03-31 | As at 2025-03-31 | As at 2025-03-31 | As at 2025-03-31 | As at 2025-03-31 | 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 reporting company | ||||||||||||||||
| Number of employees of reporting company | ||||||||||||||||
| Number of employees | 
                                                6,450
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                6,472
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                4,129
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                34,173
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                1,198
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                21,369
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                72,593
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                1,198
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                821
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                72,254
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                73,878
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                811
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                815
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                75,474
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                73,275
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                633
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
| Average number of temporary employees | 
                                                936
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                607
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                584
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                5,077
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                96
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                2,105
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                9,309
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                96
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                75
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                9,436
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                9,635
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                69
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                56
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                9,564
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                9,731
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                25
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             |