Disclosure Of Financial Instruments [Text Block]
| Concept | 
                                    
                                        2024-01-01 to 2024-12-31  | 
                            
                                
                                    
                                        2023-01-01 to 2023-12-31  | 
                            
                        
|---|---|---|
| Disclosure of financial instruments [text block] | — | — | 
| Income, expense, gains or losses of financial instruments [abstract] | ||
| Gains (losses) on financial instruments [abstract] | ||
| Other comprehensive income, before tax, financial assets measured at fair value through other comprehensive income | 
                                        
                                             
                                                521,000,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             
                                        
                                     | 
                                
                                    
                                        
                                             
                                                174,000,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             
                                        
                                     | 
                                
                            
| Gain (loss) arising from derecognition of financial assets measured at amortised cost [abstract] | ||
| Gain (loss) arising from derecognition of financial assets measured at amortised cost | 
                                        
                                             
                                                71,000,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             
                                        
                                     | 
                                
                                    
                                        
                                             
                                                75,000,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             
                                        
                                     | 
                                
                            
| Disclosure of credit risk [text block] | 
                                        
                                             | 
                                
                                    — |