Statement Of Changes In Net Assets Available For Benefits [Abstract]
| Concept | 2024-01-01 to 2024-12-31 | 2023-01-01 to 2023-12-31 | 
|---|---|---|
| Statement of changes in net assets available for benefits [abstract] | ||
| Reconciliation of changes in net assets available for benefits [abstract] | ||
| Changes in net assets available for benefits [abstract] | ||
| Other income | 
                                                628,000,000
                                                
                                                    
                                                        SEK
                                                    
                                                
                                             | 
                                                554,000,000
                                                
                                                    
                                                        SEK
                                                    
                                                
                                             | 
| Administrative expenses | 
                                                4 531
                                                
                                                    
                                                        SEK
                                                    
                                                
                                             | 
                                                4 105
                                                
                                                    
                                                        SEK
                                                    
                                                
                                             | 
| Other expense, by function | 
                                                10 6
                                                
                                                    
                                                        SEK
                                                    
                                                
                                             | 
                                                508,000,000
                                                
                                                    
                                                        SEK
                                                    
                                                
                                             | 
| Tax expense (income) | 
                                                2 683
                                                
                                                    
                                                        SEK
                                                    
                                                
                                             | 
                                                2 777
                                                
                                                    
                                                        SEK
                                                    
                                                
                                             |