Statement Of Financial Position [Abstract]
| 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 2023-12-31 | As at 2023-12-31 | As at 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 | 
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Statement of financial position [abstract] | ||||||||||||||||||
| Assets [abstract] | ||||||||||||||||||
| Property, plant and equipment | — | — | 
                                                5,149,000,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | 
                                                5,224,000,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | — | — | — | — | — | — | 
| Right-of-use assets | — | — | 
                                                559,000,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | 
                                                560,000,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | — | — | — | — | — | — | 
| Deferred tax assets | — | — | 
                                                195,000,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | 
                                                329,000,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | — | — | — | — | — | — | 
| Cash and cash equivalents | — | — | 
                                                1,078,000,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | 
                                                1,081,000,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | 
                                                1,166,000,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | — | — | — | — | — | 
| Assets | — | — | 
                                                1,434,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | 
                                                1,410,900
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | — | — | — | — | — | — | 
| Equity and liabilities [abstract] | ||||||||||||||||||
| Equity [abstract] | ||||||||||||||||||
| Issued capital | — | — | 
                                                396,000,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | 
                                                396,000,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | — | — | — | — | — | — | 
| Retained earnings | — | — | 
                                                2,745,000,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | 
                                                2,498,000,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | — | — | — | — | — | — | 
| Share premium | — | — | 
                                                2,198,000,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | 
                                                2,198,000,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | — | — | — | — | — | — | 
| Other reserves | — | — | 
                                                32,000,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | 
                                                103,000,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | — | — | — | — | — | — | 
| Equity attributable to owners of parent | — | — | 
                                                5,307,000,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | 
                                                4,989,000,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | — | — | — | — | — | — | 
| Equity | 
                                                2,745,000,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | 
                                                2,198,000,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | 
                                                5,307,000,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | 
                                                396,000,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | 
                                                53,000,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | 
                                                85,000,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | 
                                                2,198,000,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | 
                                                396,000,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | 
                                                11,000,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | 
                                                115,000,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | 
                                                2,498,000,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | 
                                                4,989,000,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | 
                                                3,711,000,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | 
                                                1,232,000,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | 
                                                396,000,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | 
                                                20,000,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | 
                                                2,198,000,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | 
                                                95,000,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | 
| Liabilities [abstract] | ||||||||||||||||||
| Deferred tax liabilities | — | — | 
                                                11,000,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | 
                                                11,000,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | — | — | — | — | — | — | 
| Liabilities | — | — | 
                                                9,033,000,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | 
                                                9,120,000,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | — | — | — | — | — | — | 
| Equity and liabilities | — | — | 
                                                1,434,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | 
                                                1,410,900
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | — | — | — | — | — | — |