Key Financial Data Of Reporting Company
| Concept | 2023-04-01 to 2023-12-31 | As at 2023-12-31 | 2023-10-01 to 2023-12-31 | As at 2023-03-31 | 2022-04-01 to 2023-03-31 | As at 2022-12-31 | 2022-04-01 to 2022-12-31 | 2022-10-01 to 2022-12-31 | 
|---|---|---|---|---|---|---|---|---|
| Key financial data of reporting company | ||||||||
| Business results of reporting company | ||||||||
| Operating revenue | 
                                                21,113,728,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                28,168,011,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                21,294,790,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Ordinary profit (loss) | 
                                                1,470,169,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                1,874,225,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                1,440,600,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Net assets | — | 
                                                24,354,931,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                23,239,013,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                22,842,104,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
| Total assets | — | 
                                                47,915,742,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                45,832,606,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                45,917,410,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
| Basic earnings (loss) per share | 
                                                153.73
                                                
                                             | — | 
                                                54.20
                                                
                                             | — | 
                                                178.51
                                                
                                             | — | 
                                                136.66
                                                
                                             | 
                                                45.90
                                                
                                             | 
| Diluted earnings per share |  | — | — | — |  | — |  | — | 
| Equity-to-asset ratio | — | 
                                                0.508
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                0.507
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                0.497
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — |