Subclassifications Of Assets, Liabilities And Equities [Abstract]
| Concept | As at 2024-12-31 | As at 2023-12-31 | As at 2022-12-31 | 
|---|---|---|---|
| Subclassifications of assets, liabilities and equities [abstract] | |||
| Property, plant and equipment [abstract] | |||
| Property, plant and equipment | 
                                                5,149,000,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | 
                                                5,224,000,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | — | 
| Intangible assets and goodwill [abstract] | |||
| Intangible assets and goodwill | 
                                                165,000,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | 
                                                150,000,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | — | 
| Investments accounted for using equity method [abstract] | |||
| Investments in joint ventures accounted for using equity method | 
                                                21,000,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | 
                                                113,000,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | — | 
| Current prepayments and current accrued income including current contract assets [abstract] | |||
| Current accrued income including current contract assets [abstract] | |||
| Current contract assets | 
                                                360,000,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | 
                                                516,000,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | — | 
| Trade and other receivables [abstract] | |||
| Trade receivables | 
                                                1,579,000,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | 
                                                1,452,000,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | — | 
| Classes of current inventories [abstract] | |||
| Current inventories | 
                                                4,795,000,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | 
                                                4,191,000,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | — | 
| Classes of current inventories, alternative [abstract] | |||
| Cash and cash equivalents [abstract] | |||
| Cash and cash equivalents | 
                                                1,078,000,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | 
                                                1,081,000,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | 
                                                1,166,000,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | 
| Classes of other provisions [abstract] | |||
| Other provisions [abstract] | |||
| Other non-current provisions | 
                                                138,000,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | 
                                                48,000,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | — | 
| Trade and other current payables [abstract] | |||
| Current accruals and current deferred income including current contract liabilities [abstract] | |||
| Current deferred income including current contract liabilities [abstract] | |||
| Current contract liabilities [abstract] | |||
| Current contract liabilities | 
                                                25,000,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | 
                                                2,000,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | — | 
| Trade and other payables [abstract] | |||
| Trade payables | 
                                                884,000,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | 
                                                781,000,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | — | 
| Categories of non-current financial liabilities [abstract] | |||
| Non-current financial liabilities | 
                                                6,359,000,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | 
                                                4,297,000,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | — | 
| Categories of current financial liabilities [abstract] | |||
| Current financial liabilities | 
                                                359,000,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | 
                                                2,601,000,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | — | 
| Issued capital [abstract] | |||
| Issued capital | 
                                                396,000,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | 
                                                396,000,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | — | 
| Retained earnings [abstract] | |||
| Retained earnings | 
                                                2,745,000,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | 
                                                2,498,000,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | — | 
| Net assets (liabilities) [abstract] | |||
| Assets | 
                                                1,434,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | 
                                                1,410,900
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | — | 
| Liabilities | 
                                                9,033,000,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | 
                                                9,120,000,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | — | 
| Net current assets (liabilities) [abstract] | |||
| Current assets | 
                                                8,095,000,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | 
                                                7,565,000,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | — | 
| Current liabilities | 
                                                1,601,000,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | 
                                                3,853,000,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | — | 
| Assets less current liabilities [abstract] |