Disclosure Of Entity's Operating Segments [Text Block]
| 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 | 2024-01-01 to 2024-12-31 | 2024-01-01 to 2024-12-31 | 2024-01-01 to 2024-12-31 | 2024-01-01 to 2024-12-31 | 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 | 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 | 
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Disclosure of entity's operating segments [text block] | — |  | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 
| Disclosure of operating segments [text block] | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 
| Disclosure of operating segments [abstract] | ||||||||||||||||
| Disclosure of operating segments [line items] | ||||||||||||||||
| Tax expense (income) | — | 
                                                66,000,000
                                                
                                                    
                                                        SEK
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | 
                                                80,000,000
                                                
                                                    
                                                        SEK
                                                    
                                                
                                             | — | — | — | — | — | 
| Profit (loss) before tax | — | 
                                                295,000,000
                                                
                                                    
                                                        SEK
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | 
                                                365,000,000
                                                
                                                    
                                                        SEK
                                                    
                                                
                                             | — | — | — | — | — | 
| Profit (loss) | 
                                                13,000,000
                                                
                                                    
                                                        SEK
                                                    
                                                
                                             | 
                                                229,000,000
                                                
                                                    
                                                        SEK
                                                    
                                                
                                             | 
                                                -
                                                
                                                    
                                                        SEK
                                                    
                                                
                                             | — | 
                                                -
                                                
                                                    
                                                        SEK
                                                    
                                                
                                             | 
                                                -
                                                
                                                    
                                                        SEK
                                                    
                                                
                                             | 
                                                216,000,000
                                                
                                                    
                                                        SEK
                                                    
                                                
                                             | 
                                                216,000,000
                                                
                                                    
                                                        SEK
                                                    
                                                
                                             | 
                                                -
                                                
                                                    
                                                        SEK
                                                    
                                                
                                             | 
                                                -
                                                
                                                    
                                                        SEK
                                                    
                                                
                                             | 
                                                285,000,000
                                                
                                                    
                                                        SEK
                                                    
                                                
                                             | — | 
                                                10,000,000
                                                
                                                    
                                                        SEK
                                                    
                                                
                                             | 
                                                275,000,000
                                                
                                                    
                                                        SEK
                                                    
                                                
                                             | 
                                                275,000,000
                                                
                                                    
                                                        SEK
                                                    
                                                
                                             | 
                                                -
                                                
                                                    
                                                        SEK
                                                    
                                                
                                             | 
| Assets | — | — | — | 
                                                1 112
                                                
                                                    
                                                        SEK
                                                    
                                                
                                             | — | — | — | — | — | — | — | 
                                                1 012
                                                
                                                    
                                                        SEK
                                                    
                                                
                                             | — | — | — | — | 
| Liabilities | — | — | — | 
                                                380,000,000
                                                
                                                    
                                                        SEK
                                                    
                                                
                                             | — | — | — | — | — | — | — | 
                                                369,000,000
                                                
                                                    
                                                        SEK
                                                    
                                                
                                             | — | — | — | — | 
| Cash flows from (used in) operating activities | — | 
                                                239,000,000
                                                
                                                    
                                                        SEK
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | 
                                                486,000,000
                                                
                                                    
                                                        SEK
                                                    
                                                
                                             | — | — | — | — | — | 
| Cash flows from (used in) investing activities | — | 
                                                44,000,000
                                                
                                                    
                                                        SEK
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | 
                                                61,000,000
                                                
                                                    
                                                        SEK
                                                    
                                                
                                             | — | — | — | — | — | 
| Cash flows from (used in) financing activities | — | 
                                                176,000,000
                                                
                                                    
                                                        SEK
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | 
                                                317,000,000
                                                
                                                    
                                                        SEK
                                                    
                                                
                                             | — | — | — | — | — |