Quarterly 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 | 
|---|---|---|---|---|---|
| Quarterly consolidated statement of cash flows | |||||
| Statement of cash flows | |||||
| Cash flows from operating activities | |||||
| Subtotal | 
                                                2,581,401,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                1,812,451,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
| Interest and dividends received | 
                                                36,652,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                40,299,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
| Interest paid | 
                                                -39,606,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                -33,124,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
| Income taxes paid | 
                                                -571,812,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                -489,133,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
| Net cash provided by (used in) operating activities | 
                                                2,020,971,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                1,346,221,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
| Cash flows from investing activities | |||||
| Purchase of property, plant and equipment | 
                                                -151,413,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                -72,011,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
| Purchase of investment securities | 
                                                -737,447,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                -463,910,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
| Proceeds from sale of investment securities | 
                                                577,478,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                654,679,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
| Other, net | 
                                                
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                -3,642,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
| Net cash provided by (used in) investing activities | 
                                                -713,945,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                -179,434,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
| Cash flows from financing activities | |||||
| Repayments of long-term borrowings | 
                                                -507,148,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                -507,148,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
| Proceeds from issuance of shares | 
                                                
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                894,600,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
| Purchase of treasury shares | 
                                                -1,149,724,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                -705,029,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
| Dividends paid | 
                                                -643,884,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                -564,917,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
| Net cash provided by (used in) financing activities | 
                                                -1,218,230,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                -894,165,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
| Net increase (decrease) in cash and cash equivalents | 
                                                88,794,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                272,621,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
| Cash and cash equivalents | — | 
                                                5,188,771,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                5,099,976,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                4,827,354,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             |