Employees
| Concept | As at 2025-03-31 | As at 2025-03-31 | As at 2025-03-31 | As at 2025-03-31 | As at 2025-03-31 | As at 2025-03-31 | As at 2025-03-31 | As at 2025-03-31 | As at 2025-03-31 | 
|---|---|---|---|---|---|---|---|---|---|
| Employees | |||||||||
| Metrics related to human capital diversity | |||||||||
| Metrics of consolidated subsidiaries | |||||||||
| Consolidated subsidiaries | 
                                                日本エヌ・ユー・エス㈱
                                                
                                             | 
                                                日揮触媒化成㈱
                                                
                                             | 
                                                日揮ビジネスサービス㈱
                                                
                                             | 
                                                青森日揮プランテック㈱
                                                
                                             | 
                                                日揮コーポレートソリューションズ㈱
                                                
                                             | 
                                                日本ファインセラミックス㈱
                                                
                                             | 
                                                JFCマテリアルズ㈱
                                                
                                             | 
                                                日揮グローバル㈱
                                                
                                             | 
                                                日揮㈱
                                                
                                             | 
| Ratio of female employees in managerial positions | 
                                                0.156
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                0.027
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                0.571
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                0.167
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                0.019
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                0.014
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
| Ratio of male employees taking childcare leave | |||||||||
| All employees | 
                                                1.00
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                0.72
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                1.00
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                1.00
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                0.62
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                0.46
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
| Differences in wages between male and female employees | |||||||||
| All employees | 
                                                0.731
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                0.785
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                0.581
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                0.678
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                0.552
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                0.742
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                0.810
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                0.668
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                0.634
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
| Regular employees | 
                                                0.786
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                0.853
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                0.657
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                0.755
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                0.595
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                0.820
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                1.030
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                0.675
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                0.636
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
| Non-regular employees | 
                                                0.489
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                0.610
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                0.394
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                0.447
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                0.137
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                1.238
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                0.288
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                0.473
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             |