Statement Of Cash Flows [Abstract]
| Concept | 2024-01-01 to 2024-12-31 | As at 2024-12-31 | 2023-01-01 to 2023-12-31 | As at 2023-12-31 | As at 2022-12-31 | 
|---|---|---|---|---|---|
| Statement of cash flows [abstract] | |||||
| Cash flows from (used in) operating activities [abstract] | |||||
| Income taxes paid (refund), classified as operating activities | 
                                                102,000,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | — | 
                                                82,000,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | — | — | 
| Cash flows from (used in) operating activities | 
                                                699,000,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | — | 
                                                3,597,000,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | — | — | 
| Cash flows from (used in) investing activities [abstract] | |||||
| Cash flows from losing control of subsidiaries or other businesses, classified as investing activities | 
                                                1,898,000,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | — | 
                                                -
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | — | — | 
| Cash flows used in obtaining control of subsidiaries or other businesses, classified as investing activities | 
                                                1,000,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | — | 
                                                2,255,000,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | — | — | 
| Proceeds from sales of property, plant and equipment, classified as investing activities | 
                                                1,000,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | — | 
                                                -
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | — | — | 
| Purchase of property, plant and equipment, classified as investing activities | 
                                                25,000,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | — | 
                                                29,000,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | — | — | 
| Purchase of intangible assets, classified as investing activities | 
                                                5,000,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | — | 
                                                5,000,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | — | — | 
| Cash flows from (used in) investing activities | 
                                                1,941,000,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | — | 
                                                2,201,000,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | — | — | 
| Cash flows from (used in) financing activities [abstract] | |||||
| Proceeds from issuing other equity instruments | 
                                                495,000,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | — | 
                                                -
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | — | — | 
| Payments of other equity instruments | 
                                                502,000,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | — | 
                                                -
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | — | — | 
| Proceeds from borrowings, classified as financing activities | 
                                                310,000,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | — | 
                                                1,165,000,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | — | — | 
| Repayments of borrowings, classified as financing activities | 
                                                582,000,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | — | 
                                                741,000,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | — | — | 
| Payments of lease liabilities, classified as financing activities | 
                                                17,000,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | — | 
                                                12,000,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | — | — | 
| Dividends paid, classified as financing activities | 
                                                629,000,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | — | 
                                                484,000,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | — | — | 
| Cash flows from (used in) financing activities | 
                                                1,076,000,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | — | 
                                                130,000,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | — | — | 
| Effect of exchange rate changes on cash and cash equivalents [abstract] | |||||
| Effect of exchange rate changes on cash and cash equivalents | 
                                                -
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | — | 
                                                4,000,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | — | — | 
| Cash and cash equivalents | — | 
                                                4,194,000,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | — | 
                                                7,910,000,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | 
                                                2,246,000,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             |