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] | |||
| Land and buildings [abstract] | |||
| Land and buildings | 
                                                375  988
                                                
                                                    
                                                        SEK
                                                    
                                                
                                             | 
                                                388  925
                                                
                                                    
                                                        SEK
                                                    
                                                
                                             | — | 
| Machinery | 
                                                215  492
                                                
                                                    
                                                        SEK
                                                    
                                                
                                             | 
                                                217  966
                                                
                                                    
                                                        SEK
                                                    
                                                
                                             | — | 
| Construction in progress | 
                                                81  594
                                                
                                                    
                                                        SEK
                                                    
                                                
                                             | 
                                                55  269
                                                
                                                    
                                                        SEK
                                                    
                                                
                                             | — | 
| Other property, plant and equipment | 
                                                51  236
                                                
                                                    
                                                        SEK
                                                    
                                                
                                             | 
                                                55  047
                                                
                                                    
                                                        SEK
                                                    
                                                
                                             | — | 
| Property, plant and equipment | 
                                                846  528
                                                
                                                    
                                                        SEK
                                                    
                                                
                                             | 
                                                842  944
                                                
                                                    
                                                        SEK
                                                    
                                                
                                             | — | 
| Intangible assets and goodwill [abstract] | |||
| Intangible assets other than goodwill [abstract] | |||
| Intangible assets under development | 
                                                5  460
                                                
                                                    
                                                        SEK
                                                    
                                                
                                             | 
                                                3  518
                                                
                                                    
                                                        SEK
                                                    
                                                
                                             | — | 
| Other intangible assets | 
                                                94 832
                                                
                                                    
                                                        SEK
                                                    
                                                
                                             | 
                                                62  606
                                                
                                                    
                                                        SEK
                                                    
                                                
                                             | — | 
| Goodwill | 
                                                1 135 809
                                                
                                                    
                                                        SEK
                                                    
                                                
                                             | 
                                                968  079
                                                
                                                    
                                                        SEK
                                                    
                                                
                                             | — | 
| Intangible assets and goodwill | 
                                                1 236 101
                                                
                                                    
                                                        SEK
                                                    
                                                
                                             | 
                                                1 034 203
                                                
                                                    
                                                        SEK
                                                    
                                                
                                             | — | 
| Investments accounted for using equity method [abstract] | |||
| Investments in associates accounted for using equity method | 
                                                24,000
                                                
                                                    
                                                        SEK
                                                    
                                                
                                             | 
                                                0
                                                
                                                    
                                                        SEK
                                                    
                                                
                                             | — | 
| Trade and other non-current receivables [abstract] | |||
| Trade and other non-current receivables | 
                                                1  809
                                                
                                                    
                                                        SEK
                                                    
                                                
                                             | 
                                                1  847
                                                
                                                    
                                                        SEK
                                                    
                                                
                                             | — | 
| Trade and other current receivables [abstract] | |||
| Current prepayments and current accrued income other than current contract assets [abstract] | |||
| Current prepayments [abstract] | |||
| Current prepaid expenses | 
                                                36  668
                                                
                                                    
                                                        SEK
                                                    
                                                
                                             | 
                                                33 783
                                                
                                                    
                                                        SEK
                                                    
                                                
                                             | — | 
| Trade and other current receivables | 
                                                806  330
                                                
                                                    
                                                        SEK
                                                    
                                                
                                             | 
                                                926  564
                                                
                                                    
                                                        SEK
                                                    
                                                
                                             | — | 
| Current prepayments and current accrued income including current contract assets [abstract] | |||
| Cash and cash equivalents [abstract] | |||
| Cash equivalents [abstract] | |||
| Cash equivalents | 
                                                308 936
                                                
                                                    
                                                        SEK
                                                    
                                                
                                             | 
                                                178  334
                                                
                                                    
                                                        SEK
                                                    
                                                
                                             | — | 
| Cash and cash equivalents | 
                                                308  936
                                                
                                                    
                                                        SEK
                                                    
                                                
                                             | 
                                                178  334
                                                
                                                    
                                                        SEK
                                                    
                                                
                                             | 
                                                345  864
                                                
                                                    
                                                        SEK
                                                    
                                                
                                             | 
| Miscellaneous assets [abstract] | |||
| Derivative financial assets | — | — | — | 
| Derivative financial assets held for hedging | 
                                                7 892
                                                
                                                    
                                                        SEK
                                                    
                                                
                                             | 
                                                20 427
                                                
                                                    
                                                        SEK
                                                    
                                                
                                             | — | 
| Classes of other provisions [abstract] | |||
| Other provisions [abstract] | |||
| Other non-current provisions | 
                                                10  292
                                                
                                                    
                                                        SEK
                                                    
                                                
                                             | 
                                                8 027
                                                
                                                    
                                                        SEK
                                                    
                                                
                                             | — | 
| Other current provisions | 
                                                5 756
                                                
                                                    
                                                        SEK
                                                    
                                                
                                             | 
                                                6 423
                                                
                                                    
                                                        SEK
                                                    
                                                
                                             | — | 
| Trade and other current payables [abstract] | |||
| Current accruals and current deferred income including current contract liabilities [abstract] | |||
| Current deferred income including current contract liabilities [abstract] | |||
| Current contract liabilities [abstract] | |||
| Current contract liabilities | 
                                                5 232
                                                
                                                    
                                                        SEK
                                                    
                                                
                                             | 
                                                219,000
                                                
                                                    
                                                        SEK
                                                    
                                                
                                             | — | 
| Trade and other current payables | 
                                                844  912
                                                
                                                    
                                                        SEK
                                                    
                                                
                                             | 
                                                834  936
                                                
                                                    
                                                        SEK
                                                    
                                                
                                             | — | 
| Categories of non-current financial liabilities [abstract] | |||
| Non-current financial liabilities | 
                                                1  067  160
                                                
                                                    
                                                        SEK
                                                    
                                                
                                             | 
                                                1 006 328
                                                
                                                    
                                                        SEK
                                                    
                                                
                                             | — | 
| Categories of current financial liabilities [abstract] | |||
| Current financial liabilities | 
                                                47  871
                                                
                                                    
                                                        SEK
                                                    
                                                
                                             | 
                                                103  836
                                                
                                                    
                                                        SEK
                                                    
                                                
                                             | — | 
| Miscellaneous liabilities [abstract] | |||
| Derivative financial liabilities | — | — | — | 
| Derivative financial liabilities held for hedging | 
                                                –
                                                
                                                    
                                                        SEK
                                                    
                                                
                                             | 
                                                –
                                                
                                                    
                                                        SEK
                                                    
                                                
                                             | — | 
| Issued capital [abstract] | |||
| Issued capital | 
                                                37 275
                                                
                                                    
                                                        SEK
                                                    
                                                
                                             | 
                                                36 559
                                                
                                                    
                                                        SEK
                                                    
                                                
                                             | — | 
| Retained earnings [abstract] | |||
| Retained earnings | 
                                                1 379 074
                                                
                                                    
                                                        SEK
                                                    
                                                
                                             | 
                                                1  306  010
                                                
                                                    
                                                        SEK
                                                    
                                                
                                             | — | 
| Miscellaneous equity [abstract] | |||
| Additional paid-in capital | 
                                                183  714
                                                
                                                    
                                                        SEK
                                                    
                                                
                                             | 
                                                114  519
                                                
                                                    
                                                        SEK
                                                    
                                                
                                             | — | 
| Net assets (liabilities) [abstract] | |||
| Assets | 
                                                3 760 700
                                                
                                                    
                                                        SEK
                                                    
                                                
                                             | 
                                                3 605 539
                                                
                                                    
                                                        SEK
                                                    
                                                
                                             | — | 
| Liabilities | 
                                                2  110  184
                                                
                                                    
                                                        SEK
                                                    
                                                
                                             | 
                                                2 075 298
                                                
                                                    
                                                        SEK
                                                    
                                                
                                             | — | 
| Net current assets (liabilities) [abstract] | |||
| Current assets | 
                                                1 668 944
                                                
                                                    
                                                        SEK
                                                    
                                                
                                             | 
                                                1 723 807
                                                
                                                    
                                                        SEK
                                                    
                                                
                                             | — | 
| Current liabilities | 
                                                909  119
                                                
                                                    
                                                        SEK
                                                    
                                                
                                             | 
                                                949  798
                                                
                                                    
                                                        SEK
                                                    
                                                
                                             | — | 
| Assets less current liabilities [abstract] |