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 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 2023-03-31 | As at 2022-03-31 | As at 2021-03-31 | 
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Employees | ||||||||||||||||||||
| Information about reporting company | ||||||||||||||||||||
| Information about employees of reporting company | ||||||||||||||||||||
| Number of employees | 
                                                2,863
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                600
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                1,132
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                52
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                1,189
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                657
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                20,069
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                4,408
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                4,634
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                1,346
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                2,087
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                677
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                850
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                804
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                327
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                7,711
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                4,388
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                4,184
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                4,174
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                4,183
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
| Average age (Years) | — | — | — | — | — | — | — | — | 
                                                42.1
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | 
| Average length of service (Years) | — | — | — | — | — | — | — | — | 
                                                13.9
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | 
| Average annual salary | — | — | — | — | — | — | — | — | 
                                                8,510,441
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — |