Statement Of Financial Position [Abstract]
| Concept | As at 2023-12-31 | As at 2023-12-31 | As at 2023-12-31 | As at 2023-12-31 | As at 2023-12-31 | As at 2022-12-31 | As at 2022-12-31 | As at 2022-12-31 | As at 2022-12-31 | As at 2022-12-31 | As at 2021-12-31 | As at 2021-12-31 | As at 2021-12-31 | As at 2021-12-31 | As at 2021-12-31 | 
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Statement of financial position [abstract] | |||||||||||||||
| Assets [abstract] | |||||||||||||||
| Non-current assets [abstract] | |||||||||||||||
| Property, plant and equipment | — | — | — | 
                                                846  528
                                                
                                                    
                                                        SEK
                                                    
                                                
                                             | — | 
                                                842  944
                                                
                                                    
                                                        SEK
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | 
| Right-of-use assets | — | — | — | 
                                                122  218
                                                
                                                    
                                                        SEK
                                                    
                                                
                                             | — | 
                                                125 737
                                                
                                                    
                                                        SEK
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | 
| Goodwill | — | — | — | 
                                                1 135 809
                                                
                                                    
                                                        SEK
                                                    
                                                
                                             | — | 
                                                968  079
                                                
                                                    
                                                        SEK
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | 
| Trade and other non-current receivables | — | — | — | 
                                                1  809
                                                
                                                    
                                                        SEK
                                                    
                                                
                                             | — | 
                                                1  847
                                                
                                                    
                                                        SEK
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | 
| Deferred tax assets | — | — | — | 
                                                7 294
                                                
                                                    
                                                        SEK
                                                    
                                                
                                             | — | 
                                                2 738
                                                
                                                    
                                                        SEK
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | 
| Non-current assets | — | — | — | 
                                                2 091 756
                                                
                                                    
                                                        SEK
                                                    
                                                
                                             | — | 
                                                1 881 732
                                                
                                                    
                                                        SEK
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | 
| Current assets [abstract] | |||||||||||||||
| Trade and other current receivables | — | — | — | 
                                                806  330
                                                
                                                    
                                                        SEK
                                                    
                                                
                                             | — | 
                                                926  564
                                                
                                                    
                                                        SEK
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | 
| Cash and cash equivalents | — | — | — | 
                                                308  936
                                                
                                                    
                                                        SEK
                                                    
                                                
                                             | — | 
                                                178  334
                                                
                                                    
                                                        SEK
                                                    
                                                
                                             | — | — | — | — | 
                                                345  864
                                                
                                                    
                                                        SEK
                                                    
                                                
                                             | — | — | — | — | 
| Current assets | — | — | — | 
                                                1 668 944
                                                
                                                    
                                                        SEK
                                                    
                                                
                                             | — | 
                                                1 723 807
                                                
                                                    
                                                        SEK
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | 
| Assets | — | — | — | 
                                                3 760 700
                                                
                                                    
                                                        SEK
                                                    
                                                
                                             | — | 
                                                3 605 539
                                                
                                                    
                                                        SEK
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | 
| Equity and liabilities [abstract] | |||||||||||||||
| Equity [abstract] | |||||||||||||||
| Issued capital | — | — | — | 
                                                37 275
                                                
                                                    
                                                        SEK
                                                    
                                                
                                             | — | 
                                                36 559
                                                
                                                    
                                                        SEK
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | 
| Retained earnings | — | — | — | 
                                                1 379 074
                                                
                                                    
                                                        SEK
                                                    
                                                
                                             | — | 
                                                1  306  010
                                                
                                                    
                                                        SEK
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | 
| Other reserves | — | — | — | 
                                                50  453
                                                
                                                    
                                                        SEK
                                                    
                                                
                                             | — | 
                                                73 153
                                                
                                                    
                                                        SEK
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | 
| Equity attributable to owners of parent | 
                                                37 275
                                                
                                                    
                                                        SEK
                                                    
                                                
                                             | 
                                                1 379 074
                                                
                                                    
                                                        SEK
                                                    
                                                
                                             | 
                                                183  714
                                                
                                                    
                                                        SEK
                                                    
                                                
                                             | 
                                                1 650 516
                                                
                                                    
                                                        SEK
                                                    
                                                
                                             | 
                                                50  453
                                                
                                                    
                                                        SEK
                                                    
                                                
                                             | 
                                                1 530 241
                                                
                                                    
                                                        SEK
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | 
| Equity | 
                                                37 275
                                                
                                                    
                                                        SEK
                                                    
                                                
                                             | 
                                                1 379 074
                                                
                                                    
                                                        SEK
                                                    
                                                
                                             | 
                                                183  714
                                                
                                                    
                                                        SEK
                                                    
                                                
                                             | 
                                                1 650 516
                                                
                                                    
                                                        SEK
                                                    
                                                
                                             | 
                                                50 453
                                                
                                                    
                                                        SEK
                                                    
                                                
                                             | 
                                                1 530 241
                                                
                                                    
                                                        SEK
                                                    
                                                
                                             | 
                                                1  306  010
                                                
                                                    
                                                        SEK
                                                    
                                                
                                             | 
                                                36  559
                                                
                                                    
                                                        SEK
                                                    
                                                
                                             | 
                                                73  153
                                                
                                                    
                                                        SEK
                                                    
                                                
                                             | 
                                                114  519
                                                
                                                    
                                                        SEK
                                                    
                                                
                                             | 
                                                1 340 937
                                                
                                                    
                                                        SEK
                                                    
                                                
                                             | 
                                                1 158 416
                                                
                                                    
                                                        SEK
                                                    
                                                
                                             | 
                                                31  443
                                                
                                                    
                                                        SEK
                                                    
                                                
                                             | 
                                                114  519
                                                
                                                    
                                                        SEK
                                                    
                                                
                                             | 
                                                36  559
                                                
                                                    
                                                        SEK
                                                    
                                                
                                             | 
| Liabilities [abstract] | |||||||||||||||
| Non-current liabilities [abstract] | |||||||||||||||
| Non-current provisions [abstract] | |||||||||||||||
| Other non-current provisions | — | — | — | 
                                                10  292
                                                
                                                    
                                                        SEK
                                                    
                                                
                                             | — | 
                                                8 027
                                                
                                                    
                                                        SEK
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | 
| Deferred tax liabilities | — | — | — | 
                                                103  530
                                                
                                                    
                                                        SEK
                                                    
                                                
                                             | — | 
                                                111 145
                                                
                                                    
                                                        SEK
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | 
| Other non-current non-financial liabilities | — | — | — | 
                                                20  083
                                                
                                                    
                                                        SEK
                                                    
                                                
                                             | — | 
                                                –
                                                
                                                    
                                                        SEK
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | 
| Non-current liabilities | — | — | — | 
                                                1 201 065
                                                
                                                    
                                                        SEK
                                                    
                                                
                                             | — | 
                                                1 125 500
                                                
                                                    
                                                        SEK
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | 
| Current liabilities [abstract] | |||||||||||||||
| Current provisions [abstract] | |||||||||||||||
| Other current provisions | — | — | — | 
                                                5 756
                                                
                                                    
                                                        SEK
                                                    
                                                
                                             | — | 
                                                6 423
                                                
                                                    
                                                        SEK
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | 
| Trade and other current payables | — | — | — | 
                                                844  912
                                                
                                                    
                                                        SEK
                                                    
                                                
                                             | — | 
                                                834  936
                                                
                                                    
                                                        SEK
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | 
| Current tax liabilities, current | — | — | — | 
                                                5  348
                                                
                                                    
                                                        SEK
                                                    
                                                
                                             | — | 
                                                4 384
                                                
                                                    
                                                        SEK
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | 
| Current liabilities | — | — | — | 
                                                909  119
                                                
                                                    
                                                        SEK
                                                    
                                                
                                             | — | 
                                                949  798
                                                
                                                    
                                                        SEK
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | 
| Liabilities | — | — | — | 
                                                2  110  184
                                                
                                                    
                                                        SEK
                                                    
                                                
                                             | — | 
                                                2 075 298
                                                
                                                    
                                                        SEK
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | 
| Equity and liabilities | — | — | — | 
                                                3 760 700
                                                
                                                    
                                                        SEK
                                                    
                                                
                                             | — | 
                                                3 605 539
                                                
                                                    
                                                        SEK
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — |