Key Financial Data Of Reporting Company
| Concept | As at 2024-12-31 | As at 2024-12-31 | As at 2024-12-31 | As at 2024-12-31 | As at 2024-12-31 | 2024-01-01 to 2024-12-31 | As at 2024-12-31 | As at 2024-12-31 | As at 2024-12-31 | As at 2024-12-31 | As at 2023-12-31 | 2023-01-01 to 2023-12-31 | As at 2023-12-31 | As at 2022-12-31 | As at 2022-12-31 | 2022-01-01 to 2022-12-31 | 2021-01-01 to 2021-12-31 | As at 2021-12-31 | As at 2021-12-31 | As at 2020-12-31 | 2020-01-01 to 2020-12-31 | As at 2020-12-31 | 
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Key financial data of reporting company | ||||||||||||||||||||||
| Business results of reporting company | ||||||||||||||||||||||
| Operating revenue | — | — | — | — | — | 
                                                118,029,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | 
                                                82,432,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                57,013,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                115,006,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                102,708,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Ordinary profit (loss) | — | — | — | — | — | 
                                                104,974,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | 
                                                70,010,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                46,363,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                104,789,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                93,473,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Profit (loss) | — | — | — | — | — | 
                                                106,396,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | 
                                                71,047,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                47,404,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                106,032,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                94,378,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Share capital | — | — | — | — | 
                                                81,690,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | 
                                                81,690,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                81,690,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                81,690,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                81,690,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
| Total number of issued shares | — | — | — | — | 
                                                552,024,717
                                                
                                                    
                                                        xbrli:shares
                                                    
                                                
                                             | — | — | — | — | — | — | — | 
                                                557,835,617
                                                
                                                    
                                                        xbrli:shares
                                                    
                                                
                                             | — | 
                                                557,835,617
                                                
                                                    
                                                        xbrli:shares
                                                    
                                                
                                             | — | — | 
                                                557,835,617
                                                
                                                    
                                                        xbrli:shares
                                                    
                                                
                                             | — | 
                                                557,835,617
                                                
                                                    
                                                        xbrli:shares
                                                    
                                                
                                             | — | — | 
| Net assets | — | — | — | — | 
                                                1,072,932,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | 
                                                1,079,851,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                1,063,296,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                1,068,749,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                1,016,964,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
| Total assets | — | — | — | — | 
                                                1,382,500,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | 
                                                1,212,335,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                1,271,496,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                1,248,088,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                1,208,485,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
| Net assets per share | — | — | — | — | 
                                                1,997.67
                                                
                                             | — | — | — | — | — | — | — | 
                                                1,989.83
                                                
                                             | — | 
                                                1,959.51
                                                
                                             | — | — | 
                                                1,970.44
                                                
                                             | — | 
                                                1,875.15
                                                
                                             | — | — | 
| Dividend paid per share | — | — | — | — | — | 
                                                120.0
                                                
                                             | — | — | — | — | — | 
                                                110.0
                                                
                                             | — | — | — | 
                                                100.0
                                                
                                             | 
                                                100.0
                                                
                                             | — | — | — | 
                                                100.0
                                                
                                             | — | 
| Interim dividend paid per share | — | — | — | — | — | 
                                                60.0
                                                
                                             | — | — | — | — | — | 
                                                50.0
                                                
                                             | — | — | — | 
                                                50.0
                                                
                                             | 
                                                50.0
                                                
                                             | — | — | — | 
                                                50.0
                                                
                                             | — | 
| Basic earnings (loss) per share | — | — | — | — | — | 
                                                196.52
                                                
                                             | — | — | — | — | — | 
                                                130.92
                                                
                                             | — | — | — | 
                                                87.37
                                                
                                             | 
                                                195.50
                                                
                                             | — | — | — | 
                                                174.03
                                                
                                             | — | 
| Diluted earnings per share | — | — | — | — | — |  | — | — | — | — | — |  | — | — | — |  |  | — | — | — |  | — | 
| Equity-to-asset ratio | — | — | — | — | 
                                                0.776
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | — | — | — | — | 
                                                0.891
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                0.836
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                0.856
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                0.842
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
| Rate of return on equity | — | — | — | — | — | 
                                                0.099
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | — | — | 
                                                0.066
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | 
                                                0.044
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                0.102
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | 
                                                0.095
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
| Price-earnings ratio | — | — | — | — | — | 
                                                43.8
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | — | — | 
                                                40.4
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | 
                                                49.3
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                21.3
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | 
                                                25.4
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
| Payout ratio | — | — | — | — | — | 
                                                0.611
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | — | — | 
                                                0.840
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | 
                                                1.145
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                0.512
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | 
                                                0.575
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
| Number of employees | 
                                                604
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                2,756
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                9,166
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                183
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                183
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                33,947
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                1,391
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                35,338
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                21,421
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                34,388
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                151
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                33,482
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                147
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                137
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                33,226
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                111
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                33,151
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
| Average number of temporary employees | 
                                                98
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                422
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                2,345
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                25
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                25
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                4,610
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                462
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                5,072
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                1,745
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                5,160
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                23
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                5,386
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                18
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                18
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                4,984
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                17
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                5,069
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
| Total shareholder return | — | — | — | — | 
                                                1.870
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | — | — | — | — | 
                                                1.167
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                0.943
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                0.895
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                0.925
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
| Total return on share price index | — | — | — | — | 
                                                1.825
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | — | — | — | — | 
                                                1.515
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                1.181
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                1.211
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                1.074
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — |