Quarterly Consolidated Balance Sheet
| Concept | As at 2025-03-31 | As at 2025-03-31 | As at 2025-03-31 | As at 2025-03-31 | As at 2025-03-31 | As at 2025-03-31 | As at 2025-03-31 | As at 2025-03-31 | As at 2025-03-31 | As at 2025-03-31 | As at 2025-03-31 | As at 2025-03-31 | As at 2025-03-31 | As at 2025-03-31 | As at 2025-03-31 | As at 2025-03-31 | As at 2025-03-31 | As at 2025-03-31 | As at 2025-03-31 | As at 2024-03-31 | As at 2024-03-31 | As at 2024-03-31 | As at 2024-03-31 | As at 2024-03-31 | As at 2024-03-31 | As at 2024-03-31 | As at 2024-03-31 | As at 2024-03-31 | As at 2024-03-31 | As at 2024-03-31 | As at 2024-03-31 | As at 2024-03-31 | As at 2024-03-31 | As at 2024-03-31 | As at 2024-03-31 | As at 2024-03-31 | As at 2024-03-31 | As at 2024-03-31 | As at 2023-03-31 | As at 2023-03-31 | As at 2023-03-31 | As at 2023-03-31 | As at 2023-03-31 | As at 2023-03-31 | As at 2023-03-31 | As at 2023-03-31 | As at 2023-03-31 | As at 2023-03-31 | As at 2023-03-31 | As at 2023-03-31 | As at 2023-03-31 | As at 2023-03-31 | As at 2023-03-31 | As at 2023-03-31 | As at 2023-03-31 | As at 2023-03-31 | As at 2023-03-31 | 
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Quarterly consolidated balance sheet | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Balance sheet | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Assets | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Current assets | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Cash and deposits | — | — | — | — | — | — | — | — | 
                                                4,936,257,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | 
                                                3,786,660,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 
                                                3,689,777,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                2,522,657,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 
| Merchandise and finished goods | — | — | — | — | — | — | — | — | 
                                                30,116,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | 
                                                29,581,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 
                                                503,792,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                503,284,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 
| Work in process | — | — | — | — | — | — | — | — | 
                                                
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | 
                                                
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 
                                                2,159,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                2,159,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 
| Raw materials and supplies | — | — | — | — | — | — | — | — | 
                                                294,264,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | 
                                                228,735,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 
                                                569,240,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                508,200,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 
| Other | — | — | — | — | — | — | — | — | 
                                                549,809,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | 
                                                25,182,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 
                                                580,621,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                22,191,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 
| Allowance for doubtful accounts | — | — | — | — | — | — | — | — | 
                                                -10,444,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | 
                                                -7,428,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 
                                                -10,669,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                -8,705,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 
| Current assets | — | — | — | — | — | — | — | — | 
                                                6,432,902,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | 
                                                5,621,278,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 
                                                5,937,084,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                5,243,441,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 
| Non-current assets | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Property, plant and equipment | — | — | — | — | — | — | — | — | 
                                                6,254,274,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | 
                                                5,935,384,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 
                                                6,463,428,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                6,124,356,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 
| Property, plant and equipment | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Buildings and structures | — | — | — | — | — | — | — | — | 
                                                12,581,089,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 
                                                12,741,343,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 
| Accumulated depreciation | — | — | — | — | — | — | — | — | 
                                                -10,233,647,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 
                                                -10,230,489,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 
| Buildings and structures, net | — | — | — | — | — | — | — | — | 
                                                2,347,442,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 
                                                2,510,853,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 
| Land | — | — | — | — | — | — | — | — | 
                                                3,638,866,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | 
                                                3,627,182,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 
                                                3,701,366,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                3,689,682,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 
| Leased assets | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 
| Leased assets, net | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 
                                                0
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 
                                                0
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 
| Construction in progress | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 
                                                20,240,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 
                                                
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 
| Other | — | — | — | — | — | — | — | — | 
                                                3,149,680,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 
                                                3,137,745,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 
| Accumulated depreciation | — | — | — | — | — | — | — | — | 
                                                -2,881,714,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 
                                                -2,886,538,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 
| Other, net | — | — | — | — | — | — | — | — | 
                                                267,965,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 
                                                251,207,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 
| Intangible assets | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Goodwill | — | — | — | — | — | — | — | — | 
                                                260,291,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 
                                                263,419,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 
| Other | — | — | — | — | — | — | — | — | 
                                                119,692,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | 
                                                55,251,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 
                                                118,398,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                55,739,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 
| Intangible assets | — | — | — | — | — | — | — | — | 
                                                379,983,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | 
                                                117,665,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 
                                                381,817,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                115,768,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 
| Investments and other assets | — | — | — | — | — | — | — | — | 
                                                3,543,596,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | 
                                                3,506,488,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 
                                                3,284,551,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                3,272,692,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 
| Investments and other assets | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Investment securities | — | — | — | — | — | — | — | — | 
                                                80,554,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | 
                                                25,417,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 
                                                76,890,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                25,417,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 
| Long-term loans receivable | — | — | — | — | — | — | — | — | 
                                                498,862,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | 
                                                496,497,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 
                                                498,977,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                493,933,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 
| Deferred tax assets | — | — | — | — | — | — | — | — | 
                                                784,114,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | 
                                                713,578,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 
                                                662,364,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                617,601,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 
| Other | — | — | — | — | — | — | — | — | 
                                                457,022,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | 
                                                134,020,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 
                                                359,348,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                34,020,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 
| Allowance for doubtful accounts | — | — | — | — | — | — | — | — | 
                                                -422,568,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | 
                                                -421,706,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 
                                                -428,150,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                -427,083,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 
| Non-current assets | — | — | — | — | — | — | — | — | 
                                                10,177,854,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | 
                                                9,559,538,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 
                                                10,129,797,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                9,512,817,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 
| Assets | — | — | — | — | — | — | — | — | 
                                                16,610,756,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | 
                                                15,180,817,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 
                                                16,066,881,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                14,756,258,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 
| Liabilities | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Current liabilities | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Short-term borrowings | — | — | — | — | — | — | — | — | 
                                                300,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | 
                                                300,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 
                                                300,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                300,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 
| Income taxes payable | — | — | — | — | — | — | — | — | 
                                                132,567,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | 
                                                105,767,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 
                                                134,264,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                104,469,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 
| Asset retirement obligations | — | — | — | — | — | — | — | — | 
                                                20,892,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | 
                                                8,172,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 
                                                34,252,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                14,605,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 
| Other | — | — | — | — | — | — | — | — | 
                                                1,420,032,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | 
                                                13,637,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 
                                                1,462,943,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                11,035,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 
| Current liabilities | — | — | — | — | — | — | — | — | 
                                                4,405,845,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | 
                                                3,727,124,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 
                                                4,304,842,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                3,653,280,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 
| Non-current liabilities | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Long-term borrowings | — | — | — | — | — | — | — | — | 
                                                4,186,259,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | 
                                                3,479,655,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 
                                                3,129,455,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                2,533,692,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 
| Retirement benefit liability | — | — | — | — | — | — | — | — | 
                                                9,480,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 
                                                13,425,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 
| Asset retirement obligations | — | — | — | — | — | — | — | — | 
                                                856,603,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | 
                                                650,518,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 
                                                731,021,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                544,615,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 
| Other | — | — | — | — | — | — | — | — | 
                                                375,011,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | 
                                                2,677,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 
                                                386,733,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                2,677,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 
| Non-current liabilities | — | — | — | — | — | — | — | — | 
                                                5,452,901,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | 
                                                5,201,286,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 
                                                4,301,270,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                4,103,652,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 
| Liabilities | — | — | — | — | — | — | — | — | 
                                                9,858,747,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | 
                                                8,928,411,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 
                                                8,606,113,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                7,756,933,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 
| Net assets | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Shareholders' equity | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Share capital | — | — | — | — | — | — | — | — | 
                                                100,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | 
                                                100,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 
                                                100,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                100,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 
| Capital surplus | — | — | — | — | — | — | — | — | 
                                                6,765,703,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | 
                                                6,789,884,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 
                                                6,783,527,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                6,807,708,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 
| Retained earnings | — | — | — | — | — | — | — | — | 
                                                507,755,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | 
                                                -13,477,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 
                                                1,239,171,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                754,019,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 
| Treasury shares | — | — | — | — | — | — | — | — | 
                                                -624,001,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | 
                                                -624,001,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 
                                                -662,402,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                -662,402,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 
| Shareholders' equity | — | — | — | — | — | — | — | — | 
                                                6,749,458,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | 
                                                6,252,406,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 
                                                7,460,296,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                6,999,325,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 
| Valuation and translation adjustments | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Valuation difference on available-for-sale securities | — | — | — | — | — | — | — | — | 
                                                1,031,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 
                                                471,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 
| Valuation and translation adjustments | — | — | — | — | — | — | — | — | 
                                                1,031,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 
                                                471,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 
| Non-controlling interests | — | — | — | — | — | — | — | — | 
                                                1,519,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 
                                                
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 
| Net assets | 
                                                1,031,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                1,519,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                6,252,406,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                6,689,884,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                -13,477,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                78,085,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                507,755,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                -91,562,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                6,752,009,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                100,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                6,749,458,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                1,031,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                -624,001,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                -624,001,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                6,252,406,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                6,789,884,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                100,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                100,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                6,765,703,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                6,999,325,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                100,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                6,807,708,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                -662,402,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                754,019,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                -662,402,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                471,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                6,707,708,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                6,783,527,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                100,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                7,460,768,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                7,460,296,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                471,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                78,085,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                6,999,325,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                100,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                1,239,171,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                675,934,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                100,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                100,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                769,878,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                6,721,439,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                7,328,260,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                7,079,506,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                480,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                6,797,258,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                6,821,439,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                -689,896,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                100,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                7,328,740,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                -689,896,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                7,079,506,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                480,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                1,120,898,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                847,963,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                78,085,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Liabilities and net assets | — | — | — | — | — | — | — | — | 
                                                16,610,756,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | 
                                                15,180,817,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 
                                                16,066,881,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                14,756,258,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — |