Statement Of Financial Position [Abstract]
| Concept | 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 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 2021-12-31 | As at 2021-12-31 | As at 2021-12-31 | As at 2021-12-31 | As at 2021-12-31 | As at 2021-12-31 | As at 2021-12-31 | As at 2021-12-31 | 
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Statement of financial position [abstract] | ||||||||||||||||||||||||
| Assets [abstract] | ||||||||||||||||||||||||
| Non-current assets [abstract] | ||||||||||||||||||||||||
| Property, plant and equipment | 
                                                -
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | — | — | — | — | — | — | — | 
                                                5 320
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 
| Investment property | 
                                                -
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | — | — | — | — | — | — | — | 
                                                562,000,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 
| Goodwill | 
                                                -
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | — | — | — | — | — | — | — | 
                                                7 867
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 
| Intangible assets other than goodwill | 
                                                -
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | — | — | — | — | — | — | — | 
                                                2 065
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 
| Investments accounted for using equity method | 
                                                -
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | — | — | — | — | — | — | — | 
                                                376,000,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 
| Deferred tax assets | 
                                                -
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | — | — | — | — | — | — | — | 
                                                1 078
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 
| Non-current assets | 
                                                -
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | — | — | — | — | — | — | — | 
                                                23 485
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 
| Current assets [abstract] | ||||||||||||||||||||||||
| Current inventories | 
                                                4,000,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | — | — | — | — | — | — | — | 
                                                3 645
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 
| Current tax assets, current | 
                                                -
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | — | — | — | — | — | — | — | 
                                                174,000,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 
| Cash and cash equivalents | 
                                                31,000,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | — | — | — | — | — | — | — | 
                                                2 560
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 
| Current assets | 
                                                18 500
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | — | — | — | — | — | — | — | 
                                                8 942
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 
| Assets | 
                                                18 500
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | — | — | — | — | — | — | — | 
                                                32 427
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 
| Equity and liabilities [abstract] | ||||||||||||||||||||||||
| Equity [abstract] | ||||||||||||||||||||||||
| Issued capital | 
                                                149,000,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | — | — | — | — | — | — | — | 
                                                149,000,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 
| Equity attributable to owners of parent | 
                                                2 162
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | — | — | — | — | — | — | — | 
                                                924,000,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 
| Non-controlling interests | 
                                                3 202
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | — | — | — | — | — | — | — | 
                                                4 511
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 
| Equity | 
                                                5 364
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | 
                                                2 104
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | 
                                                3 202
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | 
                                                218,000,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | 
                                                149,000,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | 
                                                22,000,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | 
                                                2 162
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | 
                                                403,000,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | 
                                                3 587
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | 
                                                883,000,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | 
                                                218,000,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | 
                                                4 511
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | 
                                                386,000,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | 
                                                22,000,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | 
                                                149,000,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | 
                                                924,000,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | 
                                                22,000,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | 
                                                296,000,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | 
                                                3 537
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | 
                                                930,000,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | 
                                                881,000,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | 
                                                4 418
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | 
                                                218,000,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | 
                                                149,000,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | 
| Liabilities [abstract] | ||||||||||||||||||||||||
| Non-current liabilities [abstract] | ||||||||||||||||||||||||
| Non-current provisions [abstract] | ||||||||||||||||||||||||
| Non-current provisions for employee benefits | 
                                                -
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | — | — | — | — | — | — | — | 
                                                216,000,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 
| Other non-current provisions | 
                                                -
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | — | — | — | — | — | — | — | 
                                                516,000,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 
| Deferred tax liabilities | 
                                                -
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | — | — | — | — | — | — | — | 
                                                90,000,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 
| Non-current liabilities | 
                                                -
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | — | — | — | — | — | — | — | 
                                                16 132
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 
| Current liabilities [abstract] | ||||||||||||||||||||||||
| Current provisions [abstract] | ||||||||||||||||||||||||
| Current provisions for employee benefits | 
                                                -
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | — | — | — | — | — | — | — | 
                                                13,000,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 
| Other current provisions | 
                                                25,000,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | — | — | — | — | — | — | — | 
                                                229,000,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 
| Liabilities included in disposal groups classified as held for sale | 
                                                20 250
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | — | — | — | — | — | — | — | 
                                                12,000,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 
| Current liabilities | 
                                                23 864
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | — | — | — | — | — | — | — | 
                                                12 708
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 
| Equity and liabilities | 
                                                18 500
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | — | — | — | — | — | — | — | 
                                                32 427
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — |