Statement Of Changes In Equity [Abstract]
| Concept | 2024-01-01 to 2024-12-31 | 2024-01-01 to 2024-12-31 | 2024-01-01 to 2024-12-31 | 2024-01-01 to 2024-12-31 | 2024-01-01 to 2024-12-31 | 2024-01-01 to 2024-12-31 | 2024-01-01 to 2024-12-31 | 2024-01-01 to 2024-12-31 | 2023-01-01 to 2023-12-31 | 2023-01-01 to 2023-12-31 | 2023-01-01 to 2023-12-31 | 2023-01-01 to 2023-12-31 | 2023-01-01 to 2023-12-31 | 2023-01-01 to 2023-12-31 | 2023-01-01 to 2023-12-31 | 2022-01-01 to 2022-12-31 | 2022-01-01 to 2022-12-31 | 2022-01-01 to 2022-12-31 | 2022-01-01 to 2022-12-31 | 2022-01-01 to 2022-12-31 | 2022-01-01 to 2022-12-31 | 2022-01-01 to 2022-12-31 | 
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Statement of changes in equity [abstract] | ||||||||||||||||||||||
| Statement of changes in equity [line items] | ||||||||||||||||||||||
| Increase (decrease) through transfer between revaluation surplus and retained earnings, equity | — | 
                                                2,000,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | — | — | 
                                                -
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | 
                                                313,000,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | 
                                                2,000,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | 
                                                311,000,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | 
                                                -
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | — | 
                                                -
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | 
                                                4,000,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | — | — | 
                                                4,000,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | — | — | 
                                                -
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | 
                                                1,000,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | 
                                                1,000,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | 
                                                -
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | — | 
| Increase (decrease) through exercise of options, equity | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 
                                                12,000,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | — | 
                                                6,000,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | 
                                                5,000,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | — | 
                                                6,000,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | — | 
| Decrease (increase) through tax on share-based payment transactions, equity | — | 
                                                5,000,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | — | 
                                                5,000,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | — | — | 
                                                5,000,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | — | 
                                                2,000,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | — | 
                                                2,000,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | — | 
                                                2,000,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | — | — | — | — | 
                                                1,000,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | — | — | 
                                                1,000,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | 
                                                1,000,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | 
| Purchase of treasury shares | 
                                                60,000,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | 
                                                60,000,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | — | — | — | 
                                                -
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | 
                                                60,000,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | — | 
                                                -
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | — | 
                                                -
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | 
                                                -
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | — | — | — | 
                                                24,000,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | — | 
                                                24,000,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | 
                                                -
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | — | 
                                                24,000,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | — | 
| Sale or issue of treasury shares | 
                                                54,000,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | 
                                                -
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | — | 
                                                36,000,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | — | 
                                                18,000,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | 
                                                -
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | — | 
                                                -
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | 
                                                54,000,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | 
                                                -
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | 
                                                24,000,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | 
                                                29,000,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | — | — | 
                                                77,000,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | 
                                                -
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | 
                                                7,000,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | 
                                                28,000,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | — | 
                                                7,000,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | 
                                                43,000,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | 
| Cancellation of treasury shares | 
                                                167,000,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | — | 
                                                1,000,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | — | — | 
                                                166,000,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | 
                                                -
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | — | 
                                                -
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | 
                                                566,000,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | 
                                                -
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | 
                                                563,000,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | — | 
                                                3,000,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | — | 
                                                299,000,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | 
                                                2,000,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | 
                                                -
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | 
                                                298,000,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | — | — | — |