Consolidated Statement Of Changes In Equity
| Concept | As at 2023-12-31 | As at 2023-12-31 | As at 2023-12-31 | As at 2023-12-31 | As at 2023-12-31 | As at 2023-12-31 | As at 2023-12-31 | 2023-10-01 to 2023-12-31 | 2023-10-01 to 2023-12-31 | 2023-10-01 to 2023-12-31 | 2023-10-01 to 2023-12-31 | 2023-10-01 to 2023-12-31 | 2023-10-01 to 2023-12-31 | 2023-10-01 to 2023-12-31 | As at 2023-12-31 | 2023-10-01 to 2023-12-31 | As at 2023-09-30 | As at 2023-09-30 | As at 2023-09-30 | As at 2023-09-30 | As at 2023-09-30 | As at 2023-09-30 | As at 2023-09-30 | As at 2023-09-30 | As at 2022-12-31 | As at 2022-12-31 | As at 2022-12-31 | As at 2022-12-31 | 2022-10-01 to 2022-12-31 | As at 2022-12-31 | As at 2022-12-31 | As at 2022-12-31 | 2022-10-01 to 2022-12-31 | 2022-10-01 to 2022-12-31 | 2022-10-01 to 2022-12-31 | 2022-10-01 to 2022-12-31 | 2022-10-01 to 2022-12-31 | 2022-10-01 to 2022-12-31 | 2022-10-01 to 2022-12-31 | As at 2022-12-31 | As at 2022-09-30 | As at 2022-09-30 | As at 2022-09-30 | As at 2022-09-30 | As at 2022-09-30 | As at 2022-09-30 | As at 2022-09-30 | As at 2022-09-30 | 
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Consolidated statement of changes in equity | ||||||||||||||||||||||||||||||||||||||||||||||||
| Statement of changes in equity | ||||||||||||||||||||||||||||||||||||||||||||||||
| Equity | 
                                                2,877,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                31,432,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                96,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                10,724,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                31,335,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                9,716,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                10,026,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | 
                                                -2,009,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                -2,009,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                97,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                10,035,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                3,051,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                11,668,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                9,716,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                32,462,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                32,560,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                30,029,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                -2,009,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                9,716,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                29,900,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                128,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                10,056,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                860,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | 
                                                11,276,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                10,033,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                1,233,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                11,018,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                31,123,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                30,991,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                9,716,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                -1,009,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                131,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Comprehensive income | ||||||||||||||||||||||||||||||||||||||||||||||||
| Profit (loss) | — | — | — | — | — | — | — | 
                                                0
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                -397,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                -397,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                -397,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | 
                                                567,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                564,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                564,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                3,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | 
| Other comprehensive income | — | — | — | — | — | — | — | 
                                                
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                -174,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                -174,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                -174,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | 
                                                -387,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                -387,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                -387,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | 
| Comprehensive income | — | — | — | — | — | — | — | 
                                                0
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                -397,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                -572,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                -174,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                -571,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | 
                                                180,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                176,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                -387,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                564,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                3,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | 
| Transactions with owners | ||||||||||||||||||||||||||||||||||||||||||||||||
| Purchase of treasury shares | — | — | — | — | — | — | — | 
                                                
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                0
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                0
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                0
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | 
                                                -999,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                -999,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                -999,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | 
| Dividends | — | — | — | — | — | — | — | 
                                                -1,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                -545,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                -545,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                -547,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | 
                                                -303,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                -296,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                -296,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                -6,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | 
| Share-based payment transactions | — | — | — | — | — | — | — | 
                                                
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                -9,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                -9,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                0
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                -9,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | 
                                                28,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                28,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                5,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                23,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | 
| Total transactions with owners | — | — | — | — | — | — | — | 
                                                -1,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                -9,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                -545,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                0
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                -554,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                0
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                -556,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | 
                                                -1,274,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                -999,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                -1,267,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                14,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                -305,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                23,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                -6,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — |