Disclosure Of Fair Value Measurement [Text Block]
| Concept | As at 2024-12-31 | As at 2024-12-31 | As at 2024-12-31 | As at 2024-12-31 | As at 2024-12-31 | As at 2024-12-31 | As at 2024-12-31 | 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 | 
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| Disclosure of fair value measurement [text block] | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 
| Disclosure of fair value measurement of assets [text block] | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 
| Disclosure of fair value measurement of assets [abstract] | |||||||||||||||||||||
| Disclosure of fair value measurement of assets [line items] | |||||||||||||||||||||
| Assets | — | — | — | — | — | — | 
                                                1 112
                                                
                                                    
                                                        SEK
                                                    
                                                
                                             | 
                                                1 012
                                                
                                                    
                                                        SEK
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | — | 
| Reconciliation of changes in fair value measurement, assets [abstract] | |||||||||||||||||||||
| Disclosure of fair value measurement of liabilities [text block] | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 
| Disclosure of fair value measurement of liabilities [abstract] | |||||||||||||||||||||
| Disclosure of fair value measurement of liabilities [line items] | |||||||||||||||||||||
| Liabilities | — | — | — | — | — | — | 
                                                380,000,000
                                                
                                                    
                                                        SEK
                                                    
                                                
                                             | 
                                                369,000,000
                                                
                                                    
                                                        SEK
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | — | 
| Reconciliation of changes in fair value measurement, liabilities [abstract] | |||||||||||||||||||||
| Disclosure of fair value measurement of equity [text block] | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 
| Disclosure of fair value measurement of equity [abstract] | |||||||||||||||||||||
| Disclosure of fair value measurement of equity [line items] | |||||||||||||||||||||
| Equity | 
                                                643,000,000
                                                
                                                    
                                                        SEK
                                                    
                                                
                                             | 
                                                21,000,000
                                                
                                                    
                                                        SEK
                                                    
                                                
                                             | 
                                                39,000,000
                                                
                                                    
                                                        SEK
                                                    
                                                
                                             | 
                                                693,000,000
                                                
                                                    
                                                        SEK
                                                    
                                                
                                             | 
                                                23,000,000
                                                
                                                    
                                                        SEK
                                                    
                                                
                                             | 
                                                6,000,000
                                                
                                                    
                                                        SEK
                                                    
                                                
                                             | 
                                                732,000,000
                                                
                                                    
                                                        SEK
                                                    
                                                
                                             | 
                                                643,000,000
                                                
                                                    
                                                        SEK
                                                    
                                                
                                             | 
                                                571,000,000
                                                
                                                    
                                                        SEK
                                                    
                                                
                                             | 
                                                14,000,000
                                                
                                                    
                                                        SEK
                                                    
                                                
                                             | 
                                                32,000,000
                                                
                                                    
                                                        SEK
                                                    
                                                
                                             | 
                                                21,000,000
                                                
                                                    
                                                        SEK
                                                    
                                                
                                             | 
                                                612,000,000
                                                
                                                    
                                                        SEK
                                                    
                                                
                                             | 
                                                6,000,000
                                                
                                                    
                                                        SEK
                                                    
                                                
                                             | 
                                                501,000,000
                                                
                                                    
                                                        SEK
                                                    
                                                
                                             | 
                                                14,000,000
                                                
                                                    
                                                        SEK
                                                    
                                                
                                             | 
                                                35,000,000
                                                
                                                    
                                                        SEK
                                                    
                                                
                                             | 
                                                425,000,000
                                                
                                                    
                                                        SEK
                                                    
                                                
                                             | 
                                                21,000,000
                                                
                                                    
                                                        SEK
                                                    
                                                
                                             | 
                                                466,000,000
                                                
                                                    
                                                        SEK
                                                    
                                                
                                             | 
                                                6,000,000
                                                
                                                    
                                                        SEK
                                                    
                                                
                                             | 
| Reconciliation of changes in fair value measurement, entity's own equity instruments [abstract] |