Key Financial Data Of Reporting Company
| Concept | 2023-01-01 to 2023-12-31 | As at 2023-12-31 | 2023-01-01 to 2023-12-31 | As at 2023-12-31 | As at 2023-12-31 | As at 2023-12-31 | As at 2023-12-31 | As at 2022-12-31 | 2022-01-01 to 2022-12-31 | As at 2022-12-31 | 2022-01-01 to 2022-12-31 | 2021-01-01 to 2021-12-31 | As at 2021-12-31 | As at 2021-12-31 | 2021-01-01 to 2021-12-31 | 2020-01-01 to 2020-12-31 | As at 2020-12-31 | 2020-01-01 to 2020-12-31 | As at 2020-12-31 | As at 2019-12-31 | 2019-01-01 to 2019-12-31 | 2019-01-01 to 2019-12-31 | As at 2019-12-31 | 
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Key financial data of reporting company | |||||||||||||||||||||||
| Business results of reporting company | |||||||||||||||||||||||
| Net sales | 
                                                10,025,083,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                9,557,654,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | 
                                                7,915,655,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                7,546,117,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                5,732,196,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                5,741,654,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                5,192,527,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                5,188,593,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                4,771,144,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                4,762,968,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Ordinary profit (loss) | 
                                                1,238,574,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                1,625,830,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | 
                                                921,511,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                1,081,609,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                513,057,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                514,576,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                575,633,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                556,817,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                678,872,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                660,550,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Profit (loss) | — | — | 
                                                1,191,958,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | 
                                                754,497,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                345,454,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | 
                                                413,157,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                417,231,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Share capital | — | — | — | 
                                                374,743,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | 
                                                210,062,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                178,723,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                163,530,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | 
                                                158,137,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Total number of issued shares | — | — | — | 
                                                11,726,457
                                                
                                                    
                                                        xbrli:shares
                                                    
                                                
                                             | — | — | — | — | — | 
                                                11,468,478
                                                
                                                    
                                                        xbrli:shares
                                                    
                                                
                                             | — | — | 
                                                11,418,398
                                                
                                                    
                                                        xbrli:shares
                                                    
                                                
                                             | — | — | — | 
                                                5,777,900
                                                
                                                    
                                                        xbrli:shares
                                                    
                                                
                                             | — | — | — | — | — | 
                                                5,706,000
                                                
                                                    
                                                        xbrli:shares
                                                    
                                                
                                             | 
| Net assets | — | 
                                                6,822,364,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                4,348,730,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                3,015,956,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                3,136,089,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                2,429,387,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                2,454,066,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                2,414,569,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                2,448,598,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                2,185,341,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                2,158,459,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Total assets | — | 
                                                10,874,682,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                8,166,955,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                5,658,644,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                5,646,614,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                3,800,171,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                3,819,274,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                3,759,798,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                3,792,731,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                3,269,111,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                3,243,878,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Net assets per share | — | 
                                                315.81
                                                
                                             | — | 
                                                366.30
                                                
                                             | — | — | — | 
                                                255.37
                                                
                                             | — | 
                                                270.56
                                                
                                             | — | — | 
                                                213.24
                                                
                                             | 
                                                215.40
                                                
                                             | — | — | 
                                                210.09
                                                
                                             | — | 
                                                213.05
                                                
                                             | 
                                                191.63
                                                
                                             | — | — | 
                                                189.27
                                                
                                             | 
| Dividend paid per share | — | — | 
                                                41
                                                
                                             | — | — | — | — | — | — | — | 
                                                28
                                                
                                             | 
                                                10
                                                
                                             | — | — | — | — | — | 
                                                24
                                                
                                             | — | — | — | 
                                                23
                                                
                                             | — | 
| Interim dividend paid per share | — | — |  | — | — | — | — | — | — | — |  |  | — | — | — | — | — |  | — | — | — |  | — | 
| Basic earnings (loss) per share | 
                                                67.51
                                                
                                             | — | 
                                                103.08
                                                
                                             | — | — | — | — | — | 
                                                48.67
                                                
                                             | — | 
                                                65.96
                                                
                                             | 
                                                30.29
                                                
                                             | — | — | 
                                                29.70
                                                
                                             | 
                                                36.89
                                                
                                             | — | 
                                                36.24
                                                
                                             | — | — | 
                                                37.65
                                                
                                             | 
                                                36.58
                                                
                                             | — | 
| Diluted earnings per share | 
                                                66.47
                                                
                                             | — | 
                                                101.49
                                                
                                             | — | — | — | — | — | 
                                                47.93
                                                
                                             | — | 
                                                64.96
                                                
                                             | 
                                                29.82
                                                
                                             | — | — | 
                                                29.24
                                                
                                             | 
                                                36.05
                                                
                                             | — | 
                                                35.42
                                                
                                             | — | — | 
                                                36.68
                                                
                                             | 
                                                35.65
                                                
                                             | — | 
| Equity-to-asset ratio | — | 
                                                0.340
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                0.526
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | 
                                                0.517
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                0.549
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                0.627
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                0.630
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                0.642
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                0.646
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                0.668
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                0.665
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
| Rate of return on equity | 
                                                0.236
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                0.322
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | — | — | 
                                                0.209
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                0.275
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                0.145
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                0.140
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                0.181
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                0.181
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                0.210
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                0.206
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
| Price-earnings ratio | 
                                                22.38
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                14.66
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | — | — | 
                                                25.91
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                19.12
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                24.79
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                25.28
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                64.59
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                65.75
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                19.26
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                19.83
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
| Payout ratio | — | — | 
                                                0.398
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | — | — | — | — | 
                                                0.424
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                0.330
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | — | — | 
                                                0.331
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | 
                                                0.314
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
| Net cash provided by (used in) operating activities | 
                                                225,607,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | 
                                                1,250,257,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | 
                                                316,813,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                456,102,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | 
                                                137,641,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
| Net cash provided by (used in) investing activities | 
                                                -1,377,671,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | 
                                                -486,911,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | 
                                                -31,524,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                -59,305,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | 
                                                -203,350,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
| Net cash provided by (used in) financing activities | 
                                                3,787,732,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | 
                                                646,534,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | 
                                                -404,765,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                -230,684,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | 
                                                -317,748,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
| Cash and cash equivalents | — | 
                                                5,838,745,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | 
                                                3,199,089,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | 
                                                1,784,218,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | 
                                                1,899,100,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                1,733,235,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
| Number of employees | — | 
                                                369
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                328
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                13
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                356
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                328
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                335
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                304
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                256
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                257
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                226
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                227
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                177
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                177
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
| Total shareholder return | — | — | — | 
                                                2.149
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | — | — | 
                                                1.772
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                1.067
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | 
                                                3.264
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | — | — | 
                                                1.001
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
| Total return on share price index | — | — | — | 
                                                1.789
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | — | — | 
                                                1.395
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                1.430
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | 
                                                1.268
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | — | — | 
                                                1.181
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             |