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 reporting company | ||||||||||
| Number of employees of reporting company | ||||||||||
| Number of employees | 
                                                1,865
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                2,419
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                2,292
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                1,769
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                1,722
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                2,218
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                2,043
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                1,592
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                1,550
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                2,127
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
| Average number of temporary employees | 
                                                79
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                111
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                96
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                74
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                85
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                109
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                169
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                140
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                179
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                209
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             |