Quarterly Consolidated Statement Of Cash Flows
| Concept | 2023-01-01 to 2023-12-31 | As at 2023-12-31 | 2022-01-01 to 2022-12-31 | As at 2022-12-31 | As at 2021-12-31 | 
|---|---|---|---|---|---|
| Quarterly consolidated statement of cash flows | |||||
| Statement of cash flows | |||||
| Cash flows from operating activities | |||||
| Subtotal | 
                                                6,674,525,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                9,366,603,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
| Interest and dividends received | 
                                                30,333,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                1,814,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
| Interest paid | 
                                                
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                0
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
| Income taxes paid | 
                                                -2,718,510,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                -3,200,870,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
| Net cash provided by (used in) operating activities | 
                                                3,991,831,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                6,172,506,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
| Cash flows from investing activities | |||||
| Purchase of property, plant and equipment | 
                                                -262,948,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                -178,316,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
| Other, net | 
                                                -380,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                -505,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
| Net cash provided by (used in) investing activities | 
                                                -270,448,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                -1,553,587,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
| Cash flows from financing activities | |||||
| Purchase of treasury shares | 
                                                -177,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                -106,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
| Dividends paid | 
                                                -2,380,827,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                -1,570,630,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
| Net cash provided by (used in) financing activities | 
                                                -2,381,004,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                -1,570,737,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
| Effect of exchange rate change on cash and cash equivalents | 
                                                939,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                400,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
| Net increase (decrease) in cash and cash equivalents | 
                                                1,341,318,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                3,048,582,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
| Cash and cash equivalents | — | 
                                                8,716,464,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                7,375,146,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                4,326,563,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             |