Statement Of Changes In Equity [Abstract]
| Concept | 2024-01-01 to 2024-12-31 | 2024-01-01 to 2024-12-31 | 2024-01-01 to 2024-12-31 | 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 | As at 2024-12-31 | 2024-01-01 to 2024-12-31 | 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 | 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 | 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 | 2023-01-01 to 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 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 2023-12-31 | 2023-01-01 to 2023-12-31 | 2023-01-01 to 2023-12-31 | As at 2022-12-31 | 2022-01-01 to 2022-12-31 | 2022-01-01 to 2022-12-31 | 2022-01-01 to 2022-12-31 | 2022-01-01 to 2022-12-31 | 2022-01-01 to 2022-12-31 | 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 | 2022-01-01 to 2022-12-31 | As at 2022-12-31 | As at 2022-12-31 | As at 2022-12-31 | 2022-01-01 to 2022-12-31 | As at 2022-12-31 | 2022-01-01 to 2022-12-31 | 2022-01-01 to 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 | As at 2021-12-31 | As at 2021-12-31 | 
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Statement of changes in equity [abstract] | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Statement of changes in equity [line items] | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Equity | — | — | — | 
                                                3,650,000,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | 
                                                6,654,000,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | — | 
                                                188,000,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | 
                                                37,000,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | 
                                                2,014,000,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | 
                                                411,000,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | — | 
                                                12,006,000,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | — | — | — | 
                                                1,000,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | — | 
                                                90,000,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | 
                                                12,043,000,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | — | 
                                                12,061,000,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | — | 
                                                5,402,000,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | — | — | — | — | 
                                                33,000,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | 
                                                5,827,000,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | 
                                                183,000,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | 
                                                1,263,000,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | — | 
                                                262,000,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | 
                                                12,028,000,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | 
                                                6,000,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | 
                                                390,000,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | — | — | 
                                                13,283,000,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | — | — | — | — | — | 
                                                34,000,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | 
                                                5,025,000,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | 
                                                6,832,000,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | 
                                                275,000,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | 
                                                178,000,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | — | 
                                                1,866,000,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | 
                                                13,249,000,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | 
                                                376,000,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | — | 
                                                2,000,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | — | — | 
                                                476,000,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | 
                                                344,000,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | 
                                                9,344,000,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | 
                                                177,000,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | 
                                                14,475,000,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | 
                                                25,000,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | 
                                                14,438,000,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | 
                                                36,000,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | 
                                                1,117,000,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | 
                                                4,646,000,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | 
| Changes in equity [abstract] | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Comprehensive income [abstract] | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Profit (loss) | — | — | — | — | — | — | — | — | — | — | — | — | — | 
                                                698,000,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | — | — | — | — | — | 
                                                463,000,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 
                                                1,605,000,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 
| Other comprehensive income | — | — | — | — | — | — | — | — | — | — | — | — | — | 
                                                731,000,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | — | — | — | — | — | 
                                                637,000,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 
                                                823,000,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 
| Comprehensive income | 
                                                27,000,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | — | — | — | — | 
                                                751,000,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | — | — | — | — | 
                                                707,000,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | — | 
                                                6,000,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | 
                                                33,000,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | 
                                                5,000,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | — | 
                                                11,000,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | — | — | 
                                                1,100,000,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | — | 
                                                1,101,000,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | — | 
                                                1,000,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | 
                                                488,000,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | — | 
                                                604,000,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | 
                                                17,000,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | 
                                                8,000,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | — | — | 
                                                782,000,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | 
                                                1,527,000,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | 
                                                4,000,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | 
                                                23,000,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | — | — | — | — | — | 
                                                32,000,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | — | — | — | 
                                                786,000,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | — | — | 
                                                749,000,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | 
| Dividends recognised as distributions to owners | 
                                                31,000,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | 
                                                6,000,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | 
                                                762,000,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | — | — | — | — | — | — | — | 
                                                799,000,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | — | 
                                                2,000,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | 
                                                32,000,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | — | — | — | — | — | 
                                                70,000,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | — | 
                                                68,000,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | — | 
                                                3,000,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | 
                                                816,000,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | 
                                                741,000,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | — | — | — | — | — | 
                                                8,000,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | — | — | — | — | — | — | — | 
                                                3,000,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | 
                                                418,000,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | 
                                                741,000,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | 
                                                6,000,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | 
                                                412,000,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | — | 
                                                326,000,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | 
| Increase (decrease) through share-based payment transactions, equity | 
                                                96,000,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | — | 
                                                96,000,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | 
                                                96,000,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | — | — | — | — | — | 
                                                88,000,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | — | 
                                                88,000,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | — | — | — | 
                                                88,000,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 
                                                95,000,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | 
                                                95,000,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | — | 
                                                95,000,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — |