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 reporting company | ||||||||||
| Number of employees of reporting company | ||||||||||
| Number of employees | 
                                                5,026
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                4,967
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                4,662
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                4,722
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                4,377
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                4,143
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                4,311
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             |