Subclassifications Of Assets, Liabilities And Equities [Abstract]
| Concept | As at 2024-12-31 | As at 2023-12-31 | As at 2022-12-31 | 
|---|---|---|---|
| Subclassifications of assets, liabilities and equities [abstract] | |||
| Property, plant and equipment [abstract] | |||
| Other property, plant and equipment | 
                                                0
                                                
                                                    
                                                        SEK
                                                    
                                                
                                             | 
                                                285,000
                                                
                                                    
                                                        SEK
                                                    
                                                
                                             | — | 
| Property, plant and equipment | 
                                                5  969
                                                
                                                    
                                                        SEK
                                                    
                                                
                                             | 
                                                11  191
                                                
                                                    
                                                        SEK
                                                    
                                                
                                             | — | 
| Intangible assets and goodwill [abstract] | |||
| Goodwill | 
                                                69  260
                                                
                                                    
                                                        SEK
                                                    
                                                
                                             | 
                                                119  260
                                                
                                                    
                                                        SEK
                                                    
                                                
                                             | — | 
| Intangible assets and goodwill | 
                                                69  260
                                                
                                                    
                                                        SEK
                                                    
                                                
                                             | 
                                                119 260
                                                
                                                    
                                                        SEK
                                                    
                                                
                                             | — | 
| Trade and other current receivables [abstract] | |||
| Current trade receivables | 
                                                17  161
                                                
                                                    
                                                        SEK
                                                    
                                                
                                             | 
                                                38 391
                                                
                                                    
                                                        SEK
                                                    
                                                
                                             | — | 
| Other current receivables | 
                                                1  611
                                                
                                                    
                                                        SEK
                                                    
                                                
                                             | 
                                                1  357
                                                
                                                    
                                                        SEK
                                                    
                                                
                                             | — | 
| Trade and other current receivables | 
                                                54 511
                                                
                                                    
                                                        SEK
                                                    
                                                
                                             | 
                                                87 558
                                                
                                                    
                                                        SEK
                                                    
                                                
                                             | — | 
| Categories of financial assets [abstract] | |||
| Financial assets | 
                                                12 340
                                                
                                                    
                                                        SEK
                                                    
                                                
                                             | 
                                                6  701
                                                
                                                    
                                                        SEK
                                                    
                                                
                                             | — | 
| Cash and cash equivalents [abstract] | |||
| Cash and cash equivalents | 
                                                14 931
                                                
                                                    
                                                        SEK
                                                    
                                                
                                             | 
                                                2 341
                                                
                                                    
                                                        SEK
                                                    
                                                
                                             | 
                                                4 406
                                                
                                                    
                                                        SEK
                                                    
                                                
                                             | 
| Miscellaneous current assets [abstract] | |||
| Current prepayments and other current assets | 
                                                33  557
                                                
                                                    
                                                        SEK
                                                    
                                                
                                             | 
                                                42 722
                                                
                                                    
                                                        SEK
                                                    
                                                
                                             | — | 
| Current borrowings and current portion of non-current borrowings, by type [abstract] | |||
| Other current borrowings and current portion of other non-current borrowings | 
                                                0
                                                
                                                    
                                                        SEK
                                                    
                                                
                                             | 
                                                8 009
                                                
                                                    
                                                        SEK
                                                    
                                                
                                             | — | 
| Trade and other current payables [abstract] | |||
| Other current payables | 
                                                11  657
                                                
                                                    
                                                        SEK
                                                    
                                                
                                             | 
                                                28 444
                                                
                                                    
                                                        SEK
                                                    
                                                
                                             | — | 
| Trade and other current payables | 
                                                10 433
                                                
                                                    
                                                        SEK
                                                    
                                                
                                             | 
                                                28 531
                                                
                                                    
                                                        SEK
                                                    
                                                
                                             | — | 
| Miscellaneous current liabilities [abstract] | |||
| Current accrued expenses and other current liabilities | 
                                                12  963
                                                
                                                    
                                                        SEK
                                                    
                                                
                                             | 
                                                25 339
                                                
                                                    
                                                        SEK
                                                    
                                                
                                             | — | 
| Issued capital [abstract] | |||
| Issued capital | 
                                                62 032
                                                
                                                    
                                                        SEK
                                                    
                                                
                                             | 
                                                22 557
                                                
                                                    
                                                        SEK
                                                    
                                                
                                             | — | 
| Retained earnings [abstract] | |||
| Retained earnings | 
                                                36 234
                                                
                                                    
                                                        SEK
                                                    
                                                
                                             | 
                                                162 008
                                                
                                                    
                                                        SEK
                                                    
                                                
                                             | — | 
| Accumulated other comprehensive income [abstract] | |||
| Reserve of exchange differences on translation | 
                                                14 1
                                                
                                                    
                                                        SEK
                                                    
                                                
                                             | 
                                                192,000
                                                
                                                    
                                                        SEK
                                                    
                                                
                                             | — | 
| Miscellaneous equity [abstract] | |||
| Additional paid-in capital | 
                                                65  922
                                                
                                                    
                                                        SEK
                                                    
                                                
                                             | 
                                                58 161
                                                
                                                    
                                                        SEK
                                                    
                                                
                                             | — | 
| Net assets (liabilities) [abstract] | |||
| Assets | 
                                                157 011
                                                
                                                    
                                                        SEK
                                                    
                                                
                                             | 
                                                227  051
                                                
                                                    
                                                        SEK
                                                    
                                                
                                             | — | 
| Net current assets (liabilities) [abstract] | |||
| Current assets | 
                                                69  442
                                                
                                                    
                                                        SEK
                                                    
                                                
                                             | 
                                                89  899
                                                
                                                    
                                                        SEK
                                                    
                                                
                                             | — | 
| Current liabilities | 
                                                47  420
                                                
                                                    
                                                        SEK
                                                    
                                                
                                             | 
                                                95 857
                                                
                                                    
                                                        SEK
                                                    
                                                
                                             | — | 
| Assets less current liabilities [abstract] |