Consolidated Statement Of Cash Flows
| Concept | 2024-01-01 to 2024-12-31 | As at 2024-12-31 | 2023-01-01 to 2023-12-31 | As at 2023-12-31 | As at 2022-12-31 | 
|---|---|---|---|---|---|
| Consolidated statement of cash flows | |||||
| Statement of cash flows | |||||
| Cash flows from operating activities | |||||
| Subtotal | 
                                                2,453,730,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                1,965,131,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
| Interest and dividends received | 
                                                33,009,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                18,606,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
| Interest paid | 
                                                -13,243,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                -16,611,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
| Income taxes paid | 
                                                -326,480,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                -196,562,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
| Net cash provided by (used in) operating activities | 
                                                2,148,847,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                1,779,822,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
| Cash flows from investing activities | |||||
| Purchase of property, plant and equipment | 
                                                -734,108,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                -1,204,089,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
| Net cash provided by (used in) investing activities | 
                                                -723,877,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                -1,236,452,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
| Other, net | 
                                                15,110,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                4,420,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
| Cash flows from financing activities | |||||
| Purchase of treasury shares | 
                                                -81,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                -374,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
| Dividends paid | 
                                                -433,420,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                -442,036,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
| Repayments of long-term borrowings | 
                                                -662,850,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                -732,036,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
| Net cash provided by (used in) financing activities | 
                                                -1,096,351,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                -1,548,069,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
| Other, net | 
                                                
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                3,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
| Effect of exchange rate change on cash and cash equivalents | 
                                                213,471,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                117,639,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
| Net increase (decrease) in cash and cash equivalents | 
                                                542,090,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                -887,059,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
| Cash and cash equivalents | — | 
                                                6,023,661,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                5,481,571,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                6,368,631,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             |