Employees
| Concept | As at 2024-12-31 | As at 2024-12-31 | As at 2024-12-31 | As at 2024-12-31 | As at 2024-12-31 | As at 2024-12-31 | As at 2024-12-31 | 
|---|---|---|---|---|---|---|---|
| Employees | |||||||
| Metrics related to human capital diversity | |||||||
| Metrics of consolidated subsidiaries | |||||||
| Consolidated subsidiaries | 
                                                大塚倉庫㈱
                                                
                                             | 
                                                ㈱大塚製薬工場
                                                
                                             | 
                                                大塚メディカルデバイス㈱
                                                
                                             | 
                                                大塚製薬㈱
                                                
                                             | 
                                                大塚化学㈱
                                                
                                             | 
                                                大鵬薬品工業㈱
                                                
                                             | 
                                                大塚食品㈱
                                                
                                             | 
| Ratio of female employees in managerial positions | 
                                                0.102
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                0.086
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                0.143
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                0.122
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                0.132
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                0.127
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                0.065
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
| Ratio of male employees taking childcare leave | |||||||
| All employees | 
                                                1.000
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                0.774
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                1.000
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                0.716
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                0.692
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                0.955
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                0.667
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
| Differences in wages between male and female employees | |||||||
| All employees | 
                                                0.749
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                0.832
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                0.753
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                0.792
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                0.913
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                0.664
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                0.751
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
| Regular employees | 
                                                0.835
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                0.845
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                0.790
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                0.827
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                0.916
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                0.663
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                0.807
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
| Non-regular employees | 
                                                0.718
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                0.652
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                0.512
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                0.538
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                0.882
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                0.417
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                0.541
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             |