Statement Of Changes In Equity [Abstract]
| Concept | As at 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 | As at 2024-12-31 | As at 2024-12-31 | 2024-01-01 to 2024-12-31 | As at 2024-12-31 | As at 2024-12-31 | As at 2024-12-31 | 2024-01-01 to 2024-12-31 | 2024-01-01 to 2024-12-31 | As at 2024-12-31 | 2024-01-01 to 2024-12-31 | As at 2024-12-31 | As at 2024-12-31 | 2023-01-01 to 2023-12-31 | As at 2023-12-31 | As at 2023-12-31 | 2023-01-01 to 2023-12-31 | 2023-01-01 to 2023-12-31 | 2023-01-01 to 2023-12-31 | As at 2023-12-31 | 2023-01-01 to 2023-12-31 | As at 2023-12-31 | 2023-01-01 to 2023-12-31 | 2023-01-01 to 2023-12-31 | As at 2023-12-31 | 2023-01-01 to 2023-12-31 | As at 2023-12-31 | 2023-01-01 to 2023-12-31 | As at 2023-12-31 | As at 2023-12-31 | As at 2023-12-31 | As at 2022-12-31 | As at 2022-12-31 | As at 2022-12-31 | As at 2022-12-31 | As at 2022-12-31 | As at 2022-12-31 | As at 2022-12-31 | As at 2022-12-31 | As at 2022-12-31 | 
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Statement of changes in equity [abstract] | |||||||||||||||||||||||||||||||||||||||||||||
| Statement of changes in equity [line items] | |||||||||||||||||||||||||||||||||||||||||||||
| Equity | 
                                                500,000,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | — | — | — | — | — | 
                                                1 115
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | 
                                                246,000,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | — | 
                                                5,000,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | 
                                                -
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | 
                                                51,000,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | — | — | 
                                                238,000,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | — | 
                                                177,000,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | 
                                                238,000,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | — | 
                                                6,000,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | 
                                                500,000,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | — | — | — | 
                                                833,000,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | — | 
                                                167,000,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | — | — | 
                                                -
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | — | 
                                                231,000,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | — | 
                                                4,000,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | 
                                                63,000,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | 
                                                6,000,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | 
                                                320,000,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | 
                                                500,000,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | 
                                                173,000,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | 
                                                -
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | 
                                                232,000,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | 
                                                549,000,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | 
                                                4,000,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | 
                                                41,000,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | 
                                                320,000,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | 
| Changes in equity [abstract] | |||||||||||||||||||||||||||||||||||||||||||||
| Comprehensive income [abstract] | |||||||||||||||||||||||||||||||||||||||||||||
| Profit (loss) | — | 
                                                -
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | 
                                                -
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | 
                                                282,000,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | 
                                                -
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | 
                                                -
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | — | — | 
                                                -
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | — | — | — | 
                                                282,000,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | 
                                                -
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | — | 
                                                282,000,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | — | — | 
                                                285,000,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | — | — | 
                                                -
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | 
                                                285,000,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | 
                                                -
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | — | 
                                                -
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | — | 
                                                285,000,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | 
                                                -
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | — | 
                                                -
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | — | 
                                                -
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | 
| Other comprehensive income | — | 
                                                -
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | 
                                                8,000,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | 
                                                20,000,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | 
                                                -
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | 
                                                -
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | — | — | 
                                                12,000,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | — | — | — | 
                                                -
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | 
                                                -
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | — | 
                                                20,000,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | — | — | 
                                                29,000,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | — | — | 
                                                -
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | 
                                                29,000,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | 
                                                7,000,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | — | 
                                                -
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | — | 
                                                -
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | 
                                                -
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | — | 
                                                21,000,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | — | 
                                                -
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | 
| Comprehensive income | — | 
                                                -
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | 
                                                8,000,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | 
                                                262,000,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | 
                                                -
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | 
                                                -
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | — | — | 
                                                12,000,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | — | — | — | 
                                                282,000,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | 
                                                -
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | — | 
                                                262,000,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | — | — | 
                                                314,000,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | — | — | 
                                                -
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | 
                                                314,000,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | 
                                                7,000,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | — | 
                                                -
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | — | 
                                                285,000,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | 
                                                -
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | — | 
                                                21,000,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | — | 
                                                -
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | 
| Issue of equity | — | 
                                                -
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | 
                                                2,000,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | 
                                                2,000,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | 
                                                -
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | 
                                                -
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | — | — | 
                                                -
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | — | — | — | 
                                                -
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | 
                                                -
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | — | 
                                                2,000,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | — | — | 
                                                1,000,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | — | — | 
                                                -
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | 
                                                1,000,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | 
                                                1,000,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | — | 
                                                -
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | — | 
                                                -
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | 
                                                -
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | — | 
                                                -
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | — | 
                                                -
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — |