Quarterly Statement Of Cash Flows
| Concept | 2024-01-01 to 2024-06-30 | As at 2024-06-30 | As at 2023-12-31 | 2023-01-01 to 2023-06-30 | As at 2023-06-30 | As at 2022-12-31 | 
|---|---|---|---|---|---|---|
| Quarterly statement of cash flows | ||||||
| Statement of cash flows | ||||||
| Cash flows from operating activities | ||||||
| Subtotal | 
                                                1,583,498,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                1,351,826,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
| Interest and dividends received | 
                                                4,288,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                3,878,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
| Interest paid | 
                                                -163,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                -438,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
| Income taxes paid | 
                                                -377,926,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                -78,900,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
| Net cash provided by (used in) operating activities | 
                                                1,209,697,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                1,276,366,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
| Cash flows from investing activities | ||||||
| Purchase of property, plant and equipment | 
                                                -315,952,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                -636,956,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
| Purchase of investment securities | 
                                                -961,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                -885,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
| Other, net | 
                                                -596,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                128,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
| Net cash provided by (used in) investing activities | 
                                                -595,026,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                -653,313,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
| Cash flows from financing activities | ||||||
| Repayments of long-term borrowings | 
                                                -120,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                -174,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
| Purchase of treasury shares | 
                                                
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                -80,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
| Dividends paid | 
                                                -146,151,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                -119,063,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
| Other, net | 
                                                3,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
| Net cash provided by (used in) financing activities | 
                                                -285,099,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                -322,278,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
| Net increase (decrease) in cash and cash equivalents | 
                                                329,571,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                300,774,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
| Cash and cash equivalents | — | 
                                                6,953,159,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                6,623,588,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                6,093,093,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                5,657,513,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             |