Statement Of Changes In Equity [Abstract]
| Concept | 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 | 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 | 2023-01-01 to 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 | 2023-01-01 to 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 2022-12-31 | As at 2022-12-31 | As at 2022-12-31 | As at 2022-12-31 | As at 2022-12-31 | 
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Statement of changes in equity [abstract] | |||||||||||||||||||||||||
| Statement of changes in equity [line items] | |||||||||||||||||||||||||
| Equity | — | 
                                                35 645
                                                
                                                    
                                                        SEK
                                                    
                                                
                                             | — | 
                                                62 032
                                                
                                                    
                                                        SEK
                                                    
                                                
                                             | 
                                                141,000
                                                
                                                    
                                                        SEK
                                                    
                                                
                                             | — | — | — | 
                                                65 922
                                                
                                                    
                                                        SEK
                                                    
                                                
                                             | 
                                                92 168
                                                
                                                    
                                                        SEK
                                                    
                                                
                                             | — | 
                                                116 760
                                                
                                                    
                                                        SEK
                                                    
                                                
                                             | 
                                                36 234
                                                
                                                    
                                                        SEK
                                                    
                                                
                                             | — | — | — | 
                                                192,000
                                                
                                                    
                                                        SEK
                                                    
                                                
                                             | 
                                                22 557
                                                
                                                    
                                                        SEK
                                                    
                                                
                                             | — | 
                                                58 161
                                                
                                                    
                                                        SEK
                                                    
                                                
                                             | 
                                                242 440
                                                
                                                    
                                                        SEK
                                                    
                                                
                                             | 
                                                162 008
                                                
                                                    
                                                        SEK
                                                    
                                                
                                             | 
                                                22 557
                                                
                                                    
                                                        SEK
                                                    
                                                
                                             | 
                                                286,000
                                                
                                                    
                                                        SEK
                                                    
                                                
                                             | 
                                                58 161
                                                
                                                    
                                                        SEK
                                                    
                                                
                                             | 
| Changes in equity [abstract] | |||||||||||||||||||||||||
| Comprehensive income [abstract] | |||||||||||||||||||||||||
| Profit (loss) | — | — | — | — | — | 
                                                71 879
                                                
                                                    
                                                        SEK
                                                    
                                                
                                             | 
                                                71 879
                                                
                                                    
                                                        SEK
                                                    
                                                
                                             | — | — | — | 
                                                125 774
                                                
                                                    
                                                        SEK
                                                    
                                                
                                             | — | — | 
                                                125 774
                                                
                                                    
                                                        SEK
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | 
| Other comprehensive income | — | — | — | — | — | — | 
                                                141,000
                                                
                                                    
                                                        SEK
                                                    
                                                
                                             | — | — | — | 
                                                602,000
                                                
                                                    
                                                        SEK
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 
| Comprehensive income | 
                                                -
                                                
                                                    
                                                        SEK
                                                    
                                                
                                             | — | 
                                                51,000
                                                
                                                    
                                                        SEK
                                                    
                                                
                                             | — | — | 
                                                71 879
                                                
                                                    
                                                        SEK
                                                    
                                                
                                             | 
                                                71 828
                                                
                                                    
                                                        SEK
                                                    
                                                
                                             | 
                                                -
                                                
                                                    
                                                        SEK
                                                    
                                                
                                             | — | — | 
                                                125 680
                                                
                                                    
                                                        SEK
                                                    
                                                
                                             | — | — | 
                                                125 774
                                                
                                                    
                                                        SEK
                                                    
                                                
                                             | 
                                                94,000
                                                
                                                    
                                                        SEK
                                                    
                                                
                                             | 
                                                -
                                                
                                                    
                                                        SEK
                                                    
                                                
                                             | — | — | 
                                                -
                                                
                                                    
                                                        SEK
                                                    
                                                
                                             | — | — | — | — | — | — | 
| Issue of equity | 
                                                39 475
                                                
                                                    
                                                        SEK
                                                    
                                                
                                             | — | — | — | — | — | 
                                                51 318
                                                
                                                    
                                                        SEK
                                                    
                                                
                                             | 
                                                11 843
                                                
                                                    
                                                        SEK
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 
| Decrease through other distributions to owners, equity | — | — | — | — | — | — | 
                                                4 082
                                                
                                                    
                                                        SEK
                                                    
                                                
                                             | 
                                                4 082
                                                
                                                    
                                                        SEK
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 
| Increase (decrease) through other changes, equity | — | — | 
                                                51,000
                                                
                                                    
                                                        SEK
                                                    
                                                
                                             | — | — | — | 
                                                51,000
                                                
                                                    
                                                        SEK
                                                    
                                                
                                             | — | — | — | 
                                                94,000
                                                
                                                    
                                                        SEK
                                                    
                                                
                                             | — | — | — | 
                                                94,000
                                                
                                                    
                                                        SEK
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — |