Quarterly Consolidated Statement Of Cash Flows
| Concept | 2023-01-01 to 2023-12-31 | As at 2023-12-31 | As at 2022-12-31 | 2022-01-01 to 2022-12-31 | As at 2021-12-31 | 
|---|---|---|---|---|---|
| Quarterly consolidated statement of cash flows | |||||
| Statement of cash flows | |||||
| Cash flows from operating activities | |||||
| Subtotal | 
                                                1,278,294,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                2,118,304,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Interest and dividends received | 
                                                3,691,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                3,837,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Interest paid | 
                                                -2,697,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                -2,348,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Income taxes paid | 
                                                -642,755,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                -568,127,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Net cash provided by (used in) operating activities | 
                                                716,129,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                1,630,810,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Cash flows from investing activities | |||||
| Purchase of property, plant and equipment | 
                                                -35,075,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                -46,869,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Proceeds from sale of property, plant and equipment | 
                                                181,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                1,392,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Other, net | 
                                                52,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                359,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Net cash provided by (used in) investing activities | 
                                                -68,903,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                -106,180,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Cash flows from financing activities | |||||
| Purchase of treasury shares | 
                                                -176,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                -244,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Dividends paid | 
                                                -422,327,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                -415,565,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Net cash provided by (used in) financing activities | 
                                                7,495,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                -895,810,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Effect of exchange rate change on cash and cash equivalents | 
                                                4,304,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                3,710,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Net increase (decrease) in cash and cash equivalents | 
                                                659,025,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                632,529,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Cash and cash equivalents | — | 
                                                3,762,196,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                3,103,171,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                2,470,641,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             |