Statement Of Financial Position [Abstract]
| Concept | 
                                    
                                        As at 2024-12-31  | 
                            
                                
                                    
                                        As at 2024-12-31  | 
                            
                                
                                    
                                        As at 2024-12-31  | 
                            
                                
                                    
                                        As at 2024-12-31  | 
                            
                                
                                    
                                        As at 2024-12-31  | 
                            
                                
                                    
                                        As at 2024-12-31  | 
                            
                                
                                    
                                        As at 2024-12-31  | 
                            
                                
                                    
                                        As at 2024-12-31  | 
                            
                                
                                    
                                        As at 2024-12-31  | 
                            
                                
                                    
                                        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 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 2022-12-31  | 
                            
                                
                                    
                                        As at 2022-12-31  | 
                            
                                
                                    
                                        As at 2022-12-31  | 
                            
                                
                                    
                                        As at 2022-12-31  | 
                            
                        
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Statement of financial position [abstract] | |||||||||||||||||||||||||||
| Assets [abstract] | |||||||||||||||||||||||||||
| Property, plant and equipment | — | — | — | — | — | — | — | — | 
                                        
                                             
                                                1,088,000,000
                                                
                                                    
                                                        DKK
                                                    
                                                
                                             
                                        
                                     | 
                                
                                    
                                        
                                             
                                                1,036,000,000
                                                
                                                    
                                                        DKK
                                                    
                                                
                                             
                                        
                                     | 
                                
                                    — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 
| Deferred tax assets | — | — | — | — | — | — | — | — | 
                                        
                                             
                                                566,000,000
                                                
                                                    
                                                        DKK
                                                    
                                                
                                             
                                        
                                     | 
                                
                                    
                                        
                                             
                                                494,000,000
                                                
                                                    
                                                        DKK
                                                    
                                                
                                             
                                        
                                     | 
                                
                                    — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 
| Cash and cash equivalents | — | — | — | — | — | — | — | — | 
                                        
                                             
                                                980,000,000
                                                
                                                    
                                                        DKK
                                                    
                                                
                                             
                                        
                                     | 
                                
                                    
                                        
                                             
                                                2,162,000,000
                                                
                                                    
                                                        DKK
                                                    
                                                
                                             
                                        
                                     | 
                                
                                    — | — | — | — | — | — | — | — | 
                                        
                                             
                                                990,000,000
                                                
                                                    
                                                        DKK
                                                    
                                                
                                             
                                        
                                     | 
                                
                                    — | — | — | — | — | — | — | — | 
| Assets | — | — | — | — | — | — | — | — | 
                                        
                                             
                                                30,611,000,000
                                                
                                                    
                                                        DKK
                                                    
                                                
                                             
                                        
                                     | 
                                
                                    
                                        
                                             
                                                30,642,000,000
                                                
                                                    
                                                        DKK
                                                    
                                                
                                             
                                        
                                     | 
                                
                                    — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 
| Equity and liabilities [abstract] | |||||||||||||||||||||||||||
| Equity [abstract] | |||||||||||||||||||||||||||
| Issued capital | — | — | — | — | — | — | — | — | 
                                        
                                             
                                                604,000,000
                                                
                                                    
                                                        DKK
                                                    
                                                
                                             
                                        
                                     | 
                                
                                    
                                        
                                             
                                                604,000,000
                                                
                                                    
                                                        DKK
                                                    
                                                
                                             
                                        
                                     | 
                                
                                    — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 
| Retained earnings | — | — | — | — | — | — | — | — | 
                                        
                                             
                                                13,660,000,000
                                                
                                                    
                                                        DKK
                                                    
                                                
                                             
                                        
                                     | 
                                
                                    
                                        
                                             
                                                12,781,000,000
                                                
                                                    
                                                        DKK
                                                    
                                                
                                             
                                        
                                     | 
                                
                                    — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 
| Other reserves | — | — | — | — | — | — | — | — | 
                                        
                                             
                                                3,440,000,000
                                                
                                                    
                                                        DKK
                                                    
                                                
                                             
                                        
                                     | 
                                
                                    
                                        
                                             
                                                3,798,000,000
                                                
                                                    
                                                        DKK
                                                    
                                                
                                             
                                        
                                     | 
                                
                                    — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 
| Equity | 
                                        
                                             
                                                13,660,000,000
                                                
                                                    
                                                        DKK
                                                    
                                                
                                             
                                        
                                     | 
                                
                                    
                                        
                                             
                                                604,000,000
                                                
                                                    
                                                        DKK
                                                    
                                                
                                             
                                        
                                     | 
                                
                                    
                                        
                                             
                                                -
                                                
                                                    
                                                        DKK
                                                    
                                                
                                             
                                        
                                     | 
                                
                                    
                                        
                                             
                                                786,000,000
                                                
                                                    
                                                        DKK
                                                    
                                                
                                             
                                        
                                     | 
                                
                                    
                                        
                                             
                                                2,725,000,000
                                                
                                                    
                                                        DKK
                                                    
                                                
                                             
                                        
                                     | 
                                
                                    
                                        
                                             
                                                10,824,000,000
                                                
                                                    
                                                        DKK
                                                    
                                                
                                             
                                        
                                     | 
                                
                                    
                                        
                                             
                                                -
                                                
                                                    
                                                        DKK
                                                    
                                                
                                             
                                        
                                     | 
                                
                                    
                                        
                                             
                                                71,000,000
                                                
                                                    
                                                        DKK
                                                    
                                                
                                             
                                        
                                     | 
                                
                                    
                                        
                                             
                                                10,824,000,000
                                                
                                                    
                                                        DKK
                                                    
                                                
                                             
                                        
                                     | 
                                
                                    
                                        
                                             
                                                9,587,000,000
                                                
                                                    
                                                        DKK
                                                    
                                                
                                             
                                        
                                     | 
                                
                                    
                                        
                                             
                                                12,781,000,000
                                                
                                                    
                                                        DKK
                                                    
                                                
                                             
                                        
                                     | 
                                
                                    
                                        
                                             
                                                -
                                                
                                                    
                                                        DKK
                                                    
                                                
                                             
                                        
                                     | 
                                
                                    
                                        
                                             
                                                604,000,000
                                                
                                                    
                                                        DKK
                                                    
                                                
                                             
                                        
                                     | 
                                
                                    
                                        
                                             
                                                1,062,000,000
                                                
                                                    
                                                        DKK
                                                    
                                                
                                             
                                        
                                     | 
                                
                                    
                                        
                                             
                                                -
                                                
                                                    
                                                        DKK
                                                    
                                                
                                             
                                        
                                     | 
                                
                                    
                                        
                                             
                                                2,725,000,000
                                                
                                                    
                                                        DKK
                                                    
                                                
                                             
                                        
                                     | 
                                
                                    
                                        
                                             
                                                9,587,000,000
                                                
                                                    
                                                        DKK
                                                    
                                                
                                             
                                        
                                     | 
                                
                                    
                                        
                                             
                                                11,000,000
                                                
                                                    
                                                        DKK
                                                    
                                                
                                             
                                        
                                     | 
                                
                                    
                                        
                                             
                                                6,800,000,000
                                                
                                                    
                                                        DKK
                                                    
                                                
                                             
                                        
                                     | 
                                
                                    
                                        
                                             
                                                -
                                                
                                                    
                                                        DKK
                                                    
                                                
                                             
                                        
                                     | 
                                
                                    
                                        
                                             
                                                -
                                                
                                                    
                                                        DKK
                                                    
                                                
                                             
                                        
                                     | 
                                
                                    
                                        
                                             
                                                10,514,000,000
                                                
                                                    
                                                        DKK
                                                    
                                                
                                             
                                        
                                     | 
                                
                                    
                                        
                                             
                                                3,366,000,000
                                                
                                                    
                                                        DKK
                                                    
                                                
                                             
                                        
                                     | 
                                
                                    
                                        
                                             
                                                549,000,000
                                                
                                                    
                                                        DKK
                                                    
                                                
                                             
                                        
                                     | 
                                
                                    
                                        
                                             
                                                846,000,000
                                                
                                                    
                                                        DKK
                                                    
                                                
                                             
                                        
                                     | 
                                
                                    
                                        
                                             
                                                6,800,000,000
                                                
                                                    
                                                        DKK
                                                    
                                                
                                             
                                        
                                     | 
                                
                                    
                                        
                                             
                                                51,000,000
                                                
                                                    
                                                        DKK
                                                    
                                                
                                             
                                        
                                     | 
                                
                            
| Liabilities [abstract] | |||||||||||||||||||||||||||
| Deferred tax liabilities | — | — | — | — | — | — | — | — | 
                                        
                                             
                                                1,036,000,000
                                                
                                                    
                                                        DKK
                                                    
                                                
                                             
                                        
                                     | 
                                
                                    
                                        
                                             
                                                745,000,000
                                                
                                                    
                                                        DKK
                                                    
                                                
                                             
                                        
                                     | 
                                
                                    — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 
| Equity and liabilities | — | — | — | — | — | — | — | — | 
                                        
                                             
                                                30,611,000,000
                                                
                                                    
                                                        DKK
                                                    
                                                
                                             
                                        
                                     | 
                                
                                    
                                        
                                             
                                                30,642,000,000
                                                
                                                    
                                                        DKK
                                                    
                                                
                                             
                                        
                                     | 
                                
                                    — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — |