Subclassifications Of Assets, Liabilities And Equities [Abstract]
| Concept | 
                                    
                                        As at 2023-12-31  | 
                            
                                
                                    
                                        As at 2022-12-31  | 
                            
                                
                                    
                                        As at 2021-12-31  | 
                            
                        
|---|---|---|---|
| Subclassifications of assets, liabilities and equities [abstract] | |||
| Property, plant and equipment [abstract] | |||
| Property, plant and equipment | 
                                        
                                             
                                                4  718
                                                
                                                    
                                                        SEK
                                                    
                                                
                                             
                                        
                                     | 
                                
                                    
                                        
                                             
                                                5 350
                                                
                                                    
                                                        SEK
                                                    
                                                
                                             
                                        
                                     | 
                                
                                    — | 
| Intangible assets and goodwill [abstract] | |||
| Intangible assets and goodwill | 
                                        
                                             
                                                111   9 4 9
                                                
                                                    
                                                        SEK
                                                    
                                                
                                             
                                        
                                     | 
                                
                                    
                                        
                                             
                                                112   6 8 7
                                                
                                                    
                                                        SEK
                                                    
                                                
                                             
                                        
                                     | 
                                
                                    — | 
| Trade and other non-current receivables [abstract] | |||
| Other non-current receivables | 
                                        
                                             
                                                3  268
                                                
                                                    
                                                        SEK
                                                    
                                                
                                             
                                        
                                     | 
                                
                                    
                                        
                                             
                                                3  268
                                                
                                                    
                                                        SEK
                                                    
                                                
                                             
                                        
                                     | 
                                
                                    — | 
| Trade and other current receivables [abstract] | |||
| Current trade receivables | 
                                        
                                             
                                                1 4 2    17 0
                                                
                                                    
                                                        SEK
                                                    
                                                
                                             
                                        
                                     | 
                                
                                    
                                        
                                             
                                                101  051
                                                
                                                    
                                                        SEK
                                                    
                                                
                                             
                                        
                                     | 
                                
                                    — | 
| Other current receivables | 
                                        
                                             
                                                11   4 0 4
                                                
                                                    
                                                        SEK
                                                    
                                                
                                             
                                        
                                     | 
                                
                                    
                                        
                                             
                                                5 352
                                                
                                                    
                                                        SEK
                                                    
                                                
                                             
                                        
                                     | 
                                
                                    — | 
| Current prepayments and current accrued income including current contract assets [abstract] | |||
| Current prepayments and current accrued income including current contract assets | 
                                        
                                             
                                                25  099
                                                
                                                    
                                                        SEK
                                                    
                                                
                                             
                                        
                                     | 
                                
                                    
                                        
                                             
                                                29  160
                                                
                                                    
                                                        SEK
                                                    
                                                
                                             
                                        
                                     | 
                                
                                    — | 
| Classes of current inventories [abstract] | |||
| Current inventories | 
                                        
                                             
                                                1 553
                                                
                                                    
                                                        SEK
                                                    
                                                
                                             
                                        
                                     | 
                                
                                    
                                        
                                             
                                                680,000
                                                
                                                    
                                                        SEK
                                                    
                                                
                                             
                                        
                                     | 
                                
                                    — | 
| Classes of current inventories, alternative [abstract] | |||
| Cash and cash equivalents [abstract] | |||
| Cash and cash equivalents | 
                                        
                                             
                                                107  898
                                                
                                                    
                                                        SEK
                                                    
                                                
                                             
                                        
                                     | 
                                
                                    
                                        
                                             
                                                117  0 0 2
                                                
                                                    
                                                        SEK
                                                    
                                                
                                             
                                        
                                     | 
                                
                                    
                                        
                                             
                                                130    611
                                                
                                                    
                                                        SEK
                                                    
                                                
                                             
                                        
                                     | 
                                
                            
| Classes of other provisions [abstract] | |||
| Other provisions [abstract] | |||
| Other non-current provisions | 
                                        
                                             
                                                3  522
                                                
                                                    
                                                        SEK
                                                    
                                                
                                             
                                        
                                     | 
                                
                                    
                                        
                                             
                                                3 294
                                                
                                                    
                                                        SEK
                                                    
                                                
                                             
                                        
                                     | 
                                
                                    — | 
| Other current provisions | 
                                        
                                             
                                                1  274
                                                
                                                    
                                                        SEK
                                                    
                                                
                                             
                                        
                                     | 
                                
                                    
                                        
                                             
                                                2  800
                                                
                                                    
                                                        SEK
                                                    
                                                
                                             
                                        
                                     | 
                                
                                    — | 
| Trade and other current payables [abstract] | |||
| Current trade payables | 
                                        
                                             
                                                31 555
                                                
                                                    
                                                        SEK
                                                    
                                                
                                             
                                        
                                     | 
                                
                                    
                                        
                                             
                                                41   607
                                                
                                                    
                                                        SEK
                                                    
                                                
                                             
                                        
                                     | 
                                
                                    — | 
| Current accruals and current deferred income including current contract liabilities [abstract] | |||
| Current accruals and current deferred income including current contract liabilities | 
                                        
                                             
                                                74  0 6 4
                                                
                                                    
                                                        SEK
                                                    
                                                
                                             
                                        
                                     | 
                                
                                    
                                        
                                             
                                                60  427
                                                
                                                    
                                                        SEK
                                                    
                                                
                                             
                                        
                                     | 
                                
                                    — | 
| Miscellaneous current liabilities [abstract] | |||
| Other current liabilities | 
                                        
                                             
                                                42 489
                                                
                                                    
                                                        SEK
                                                    
                                                
                                             
                                        
                                     | 
                                
                                    
                                        
                                             
                                                40 088
                                                
                                                    
                                                        SEK
                                                    
                                                
                                             
                                        
                                     | 
                                
                                    — | 
| Issued capital [abstract] | |||
| Issued capital | 
                                        
                                             
                                                21 053
                                                
                                                    
                                                        SEK
                                                    
                                                
                                             
                                        
                                     | 
                                
                                    
                                        
                                             
                                                21 053
                                                
                                                    
                                                        SEK
                                                    
                                                
                                             
                                        
                                     | 
                                
                                    — | 
| Retained earnings [abstract] | |||
| Retained earnings | 
                                        
                                             
                                                219   922
                                                
                                                    
                                                        SEK
                                                    
                                                
                                             
                                        
                                     | 
                                
                                    
                                        
                                             
                                                188  514
                                                
                                                    
                                                        SEK
                                                    
                                                
                                             
                                        
                                     | 
                                
                                    — | 
| Miscellaneous equity [abstract] | |||
| Additional paid-in capital | 
                                        
                                             
                                                44  004
                                                
                                                    
                                                        SEK
                                                    
                                                
                                             
                                        
                                     | 
                                
                                    
                                        
                                             
                                                44  004
                                                
                                                    
                                                        SEK
                                                    
                                                
                                             
                                        
                                     | 
                                
                                    — | 
| Net assets (liabilities) [abstract] | |||
| Assets | 
                                        
                                             
                                                459   413
                                                
                                                    
                                                        SEK
                                                    
                                                
                                             
                                        
                                     | 
                                
                                    
                                        
                                             
                                                433  849
                                                
                                                    
                                                        SEK
                                                    
                                                
                                             
                                        
                                     | 
                                
                                    — | 
| Net current assets (liabilities) [abstract] | |||
| Current assets | 
                                        
                                             
                                                303  806
                                                
                                                    
                                                        SEK
                                                    
                                                
                                             
                                        
                                     | 
                                
                                    
                                        
                                             
                                                266  620
                                                
                                                    
                                                        SEK
                                                    
                                                
                                             
                                        
                                     | 
                                
                                    — | 
| Current liabilities | 
                                        
                                             
                                                149   382
                                                
                                                    
                                                        SEK
                                                    
                                                
                                             
                                        
                                     | 
                                
                                    
                                        
                                             
                                                14 4    9 2 2
                                                
                                                    
                                                        SEK
                                                    
                                                
                                             
                                        
                                     | 
                                
                                    — | 
| Assets less current liabilities [abstract] |