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] | |||
| Intangible assets and goodwill [abstract] | |||
| Intangible assets and goodwill | 
                                                25 075
                                                
                                                    
                                                        SEK
                                                    
                                                
                                             | 
                                                15 843
                                                
                                                    
                                                        SEK
                                                    
                                                
                                             | — | 
| Investments accounted for using equity method [abstract] | |||
| Investments accounted for using equity method | 
                                                34,000,000
                                                
                                                    
                                                        SEK
                                                    
                                                
                                             | 
                                                49,000,000
                                                
                                                    
                                                        SEK
                                                    
                                                
                                             | — | 
| Trade and other current receivables [abstract] | |||
| Current trade receivables | 
                                                12 424
                                                
                                                    
                                                        SEK
                                                    
                                                
                                             | 
                                                10 455
                                                
                                                    
                                                        SEK
                                                    
                                                
                                             | — | 
| Other current receivables | 
                                                3 868
                                                
                                                    
                                                        SEK
                                                    
                                                
                                             | 
                                                3 093
                                                
                                                    
                                                        SEK
                                                    
                                                
                                             | — | 
| Classes of current inventories [abstract] | |||
| Current inventories | 
                                                19 191
                                                
                                                    
                                                        SEK
                                                    
                                                
                                             | 
                                                18 747
                                                
                                                    
                                                        SEK
                                                    
                                                
                                             | — | 
| Classes of current inventories, alternative [abstract] | |||
| Cash and cash equivalents [abstract] | |||
| Cash and cash equivalents | 
                                                7 179
                                                
                                                    
                                                        SEK
                                                    
                                                
                                             | 
                                                6 401
                                                
                                                    
                                                        SEK
                                                    
                                                
                                             | 
                                                7 326
                                                
                                                    
                                                        SEK
                                                    
                                                
                                             | 
| Borrowings [abstract] | |||
| Non-current portion of non-current borrowings | 
                                                19 612
                                                
                                                    
                                                        SEK
                                                    
                                                
                                             | 
                                                11 822
                                                
                                                    
                                                        SEK
                                                    
                                                
                                             | — | 
| Current borrowings and current portion of non-current borrowings [abstract] | |||
| Current borrowings and current portion of non-current borrowings | 
                                                2 405
                                                
                                                    
                                                        SEK
                                                    
                                                
                                             | 
                                                2 153
                                                
                                                    
                                                        SEK
                                                    
                                                
                                             | — | 
| Non-current portion of non-current borrowings, by type [abstract] | |||
| Current borrowings and current portion of non-current borrowings, by type [abstract] | |||
| Trade and other non-current payables [abstract] | |||
| Other non-current payables | 
                                                165,000,000
                                                
                                                    
                                                        SEK
                                                    
                                                
                                             | 
                                                83,000,000
                                                
                                                    
                                                        SEK
                                                    
                                                
                                             | — | 
| Trade and other current payables [abstract] | |||
| Trade and other current payables | 
                                                5 756
                                                
                                                    
                                                        SEK
                                                    
                                                
                                             | 
                                                5 902
                                                
                                                    
                                                        SEK
                                                    
                                                
                                             | — | 
| Miscellaneous non-current liabilities [abstract] | |||
| Non-current net defined benefit liability | 
                                                201,000,000
                                                
                                                    
                                                        SEK
                                                    
                                                
                                             | 
                                                251,000,000
                                                
                                                    
                                                        SEK
                                                    
                                                
                                             | — | 
| Miscellaneous current liabilities [abstract] | |||
| Other current liabilities | 
                                                9 143
                                                
                                                    
                                                        SEK
                                                    
                                                
                                             | 
                                                7 951
                                                
                                                    
                                                        SEK
                                                    
                                                
                                             | — | 
| Issued capital [abstract] | |||
| Issued capital | 
                                                500,000,000
                                                
                                                    
                                                        SEK
                                                    
                                                
                                             | 
                                                500,000,000
                                                
                                                    
                                                        SEK
                                                    
                                                
                                             | — | 
| Retained earnings [abstract] | |||
| Retained earnings | 
                                                39 947
                                                
                                                    
                                                        SEK
                                                    
                                                
                                             | 
                                                35 452
                                                
                                                    
                                                        SEK
                                                    
                                                
                                             | — | 
| Miscellaneous equity [abstract] | |||
| Additional paid-in capital | 
                                                117,000,000
                                                
                                                    
                                                        SEK
                                                    
                                                
                                             | 
                                                105,000,000
                                                
                                                    
                                                        SEK
                                                    
                                                
                                             | — | 
| Net assets (liabilities) [abstract] | |||
| Assets | 
                                                83 589
                                                
                                                    
                                                        SEK
                                                    
                                                
                                             | 
                                                67 784
                                                
                                                    
                                                        SEK
                                                    
                                                
                                             | — | 
| Net current assets (liabilities) [abstract] | |||
| Current assets | 
                                                45 204
                                                
                                                    
                                                        SEK
                                                    
                                                
                                             | 
                                                41 120
                                                
                                                    
                                                        SEK
                                                    
                                                
                                             | — | 
| Current liabilities | 
                                                18 252
                                                
                                                    
                                                        SEK
                                                    
                                                
                                             | 
                                                17 003
                                                
                                                    
                                                        SEK
                                                    
                                                
                                             | — | 
| Assets less current liabilities [abstract] |