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 | 2022-01-01 to 2022-12-31 | As at 2021-12-31 | 
|---|---|---|---|---|---|---|---|
| Statement of cash flows [abstract] | |||||||
| Cash flows from (used in) operating activities [abstract] | |||||||
| Dividends received, classified as operating activities | 
                                                8,000,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | — | 
                                                13,000,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | — | — | 
                                                12,000,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | — | 
| Interest paid, classified as operating activities | 
                                                261,000,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | — | 
                                                250,000,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | — | — | 
                                                205,000,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | — | 
| Interest received, classified as operating activities | 
                                                83,000,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | — | 
                                                53,000,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | — | — | 
                                                15,000,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | — | 
| Income taxes paid (refund), classified as operating activities | 
                                                173,000,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | — | 
                                                152,000,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | — | — | 
                                                333,000,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | — | 
| Cash flows from (used in) investing activities [abstract] | |||||||
| Cash flows from losing control of subsidiaries or other businesses, classified as investing activities | 
                                                126,000,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | — | 
                                                80,000,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | — | — | 
                                                124,000,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | — | 
| Cash flows used in obtaining control of subsidiaries or other businesses, classified as investing activities | 
                                                8,000,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | — | 
                                                73,000,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | — | — | 
                                                712,000,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | — | 
| Other cash receipts from sales of equity or debt instruments of other entities, classified as investing activities | 
                                                57,000,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | — | 
                                                48,000,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | — | — | 
                                                78,000,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | — | 
| Other cash payments to acquire equity or debt instruments of other entities, classified as investing activities | 
                                                123,000,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | — | 
                                                92,000,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | — | — | 
                                                116,000,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | — | 
| Proceeds from sales of property, plant and equipment, classified as investing activities | 
                                                13,000,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | — | 
                                                90,000,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | — | — | 
                                                18,000,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | — | 
| Purchase of property, plant and equipment, classified as investing activities | 
                                                317,000,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | — | 
                                                345,000,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | — | — | 
                                                444,000,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | — | 
| Purchase of intangible assets, classified as investing activities | 
                                                118,000,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | — | 
                                                96,000,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | — | — | 
                                                105,000,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | — | 
| Cash flows from (used in) financing activities [abstract] | |||||||
| Payments to acquire or redeem entity's shares | 
                                                411,000,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | — | 
                                                662,000,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | — | — | 
                                                187,000,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | — | 
| Increase (decrease) in cash and cash equivalents before effect of exchange rate changes | 
                                                487,000,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | — | 
                                                776,000,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | — | — | 
                                                1,172,000,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | — | 
| Effect of exchange rate changes on cash and cash equivalents [abstract] | |||||||
| Effect of exchange rate changes on cash and cash equivalents | 
                                                45,000,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | — | 
                                                79,000,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | — | — | 
                                                41,000,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | — | 
| Cash and cash equivalents | — | 
                                                2,401,000,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | — | 
                                                1,869,000,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | 
                                                1,172,000,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             | — | 
                                                2,303,000,000
                                                
                                                    
                                                        EUR
                                                    
                                                
                                             |