Statement Of Changes In Net Assets Available For Benefits [Abstract]
| Concept | 2024-01-01 to 2024-12-31 | 2023-01-01 to 2023-12-31 | 2022-01-01 to 2022-12-31 | 
|---|---|---|---|
| Statement of changes in net assets available for benefits [abstract] | |||
| Reconciliation of changes in net assets available for benefits [abstract] | |||
| Changes in net assets available for benefits [abstract] | |||
| Other income | 
                                                590,000,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | 
                                                112,000,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | 
                                                127,000,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | 
| Other expense, by function | 
                                                1,019,000,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | 
                                                645,000,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | 
                                                109,000,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | 
| Tax expense (income) | 
                                                963,000,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | 
                                                73,000,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | 
                                                113,000,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             |