Shareholdings
| Concept | As at 2023-09-30 | As at 2023-09-30 | As at 2023-09-30 | As at 2023-09-30 | As at 2023-09-30 | As at 2023-09-30 | As at 2023-09-30 | As at 2023-09-30 | As at 2023-09-30 | As at 2023-09-30 | As at 2023-09-30 | As at 2023-09-30 | As at 2023-09-30 | As at 2022-09-30 | As at 2022-09-30 | As at 2022-09-30 | As at 2022-09-30 | As at 2022-09-30 | As at 2022-09-30 | As at 2022-09-30 | As at 2022-09-30 | As at 2022-09-30 | As at 2022-09-30 | As at 2022-09-30 | As at 2022-09-30 | As at 2022-09-30 | 
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Shareholdings | ||||||||||||||||||||||||||
| Reporting company | ||||||||||||||||||||||||||
| Details of specified investment shares held for purposes other than pure investment | ||||||||||||||||||||||||||
| Issue | 
                                                TDCソフト㈱
                                                
                                             | 
                                                東京電力ホールディングス㈱
                                                
                                             | 
                                                北陸電力㈱
                                                
                                             | 
                                                西日本旅客鉄道㈱
                                                
                                             | 
                                                応用地質㈱
                                                
                                             | 
                                                住友不動産㈱
                                                
                                             | 
                                                中部電力㈱
                                                
                                             | 
                                                ㈱パスコ
                                                
                                             | 
                                                ID&Eホールディングス㈱
                                                
                                             | 
                                                ㈱建設技術研究所
                                                
                                             | 
                                                東海旅客鉄道㈱
                                                
                                             | 
                                                ㈱きもと
                                                
                                             | 
                                                日本国土開発㈱
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | — | 
| Number of shares | 
                                                315,000
                                                
                                                    
                                                        xbrli:shares
                                                    
                                                
                                             | 
                                                6,498
                                                
                                                    
                                                        xbrli:shares
                                                    
                                                
                                             | 
                                                10,613
                                                
                                                    
                                                        xbrli:shares
                                                    
                                                
                                             | 
                                                10,000
                                                
                                                    
                                                        xbrli:shares
                                                    
                                                
                                             | 
                                                121
                                                
                                                    
                                                        xbrli:shares
                                                    
                                                
                                             | 
                                                14,300
                                                
                                                    
                                                        xbrli:shares
                                                    
                                                
                                             | 
                                                5,332
                                                
                                                    
                                                        xbrli:shares
                                                    
                                                
                                             | 
                                                200
                                                
                                                    
                                                        xbrli:shares
                                                    
                                                
                                             | 
                                                220
                                                
                                                    
                                                        xbrli:shares
                                                    
                                                
                                             | 
                                                82,528
                                                
                                                    
                                                        xbrli:shares
                                                    
                                                
                                             | 
                                                5,800
                                                
                                                    
                                                        xbrli:shares
                                                    
                                                
                                             | 
                                                40,000
                                                
                                                    
                                                        xbrli:shares
                                                    
                                                
                                             | 
                                                3,189,000
                                                
                                                    
                                                        xbrli:shares
                                                    
                                                
                                             | 
                                                10,613
                                                
                                                    
                                                        xbrli:shares
                                                    
                                                
                                             | 
                                                6,498
                                                
                                                    
                                                        xbrli:shares
                                                    
                                                
                                             | 
                                                10,000
                                                
                                                    
                                                        xbrli:shares
                                                    
                                                
                                             | 
                                                121
                                                
                                                    
                                                        xbrli:shares
                                                    
                                                
                                             | 
                                                315,000
                                                
                                                    
                                                        xbrli:shares
                                                    
                                                
                                             | 
                                                200
                                                
                                                    
                                                        xbrli:shares
                                                    
                                                
                                             | 
                                                14,300
                                                
                                                    
                                                        xbrli:shares
                                                    
                                                
                                             | 
                                                220
                                                
                                                    
                                                        xbrli:shares
                                                    
                                                
                                             | 
                                                5,332
                                                
                                                    
                                                        xbrli:shares
                                                    
                                                
                                             | 
                                                40,000
                                                
                                                    
                                                        xbrli:shares
                                                    
                                                
                                             | 
                                                5,800
                                                
                                                    
                                                        xbrli:shares
                                                    
                                                
                                             | 
                                                82,528
                                                
                                                    
                                                        xbrli:shares
                                                    
                                                
                                             | 
                                                3,189,000
                                                
                                                    
                                                        xbrli:shares
                                                    
                                                
                                             | 
| Carrying amount | 
                                                532,980,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                4,345,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                8,554,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                61,850,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                301,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                55,569,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                10,168,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                340,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                786,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                370,963,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                105,415,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                7,440,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                2,117,496,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                5,157,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                3,002,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                55,400,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                226,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                389,970,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                256,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                47,018,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                785,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                6,952,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                9,120,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                98,223,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                234,049,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                1,999,503,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Whether issuer of aforementioned shares holds reporting company's shares | 
                                                有
                                                
                                             | 
                                                無
                                                
                                             | 
                                                有
                                                
                                             | 
                                                有
                                                
                                             | 
                                                無
                                                
                                             | 
                                                有
                                                
                                             | 
                                                無
                                                
                                             | 
                                                有
                                                
                                             | 
                                                無
                                                
                                             | 
                                                有
                                                
                                             | 
                                                無
                                                
                                             | 
                                                有
                                                
                                             | 
                                                有
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | — |