Statement Of Changes In Equity [Abstract]
| Concept | 
                                    
                                        2021-01-01 to 2021-12-31  | 
                            
                                
                                    
                                        2021-01-01 to 2021-12-31  | 
                            
                                
                                    
                                        2021-01-01 to 2021-12-31  | 
                            
                                
                                    
                                        2021-01-01 to 2021-12-31  | 
                            
                                
                                    
                                        2021-01-01 to 2021-12-31  | 
                            
                                
                                    
                                        2021-01-01 to 2021-12-31  | 
                            
                                
                                    
                                        2020-01-01 to 2020-12-31  | 
                            
                                
                                    
                                        2020-01-01 to 2020-12-31  | 
                            
                                
                                    
                                        2020-01-01 to 2020-12-31  | 
                            
                                
                                    
                                        2020-01-01 to 2020-12-31  | 
                            
                                
                                    
                                        2020-01-01 to 2020-12-31  | 
                            
                        
|---|---|---|---|---|---|---|---|---|---|---|---|
| Statement of changes in equity [abstract] | |||||||||||
| Statement of changes in equity [line items] | |||||||||||
| Dividends recognised as distributions to non-controlling interests | 
                                        
                                             
                                                1,000
                                                
                                                    
                                                        BGN
                                                    
                                                
                                             
                                        
                                     | 
                                
                                    — | — | — | 
                                        
                                             
                                                1,000
                                                
                                                    
                                                        BGN
                                                    
                                                
                                             
                                        
                                     | 
                                
                                    — | — | 
                                        
                                             
                                                2,000
                                                
                                                    
                                                        BGN
                                                    
                                                
                                             
                                        
                                     | 
                                
                                    
                                        
                                             
                                                2,000
                                                
                                                    
                                                        BGN
                                                    
                                                
                                             
                                        
                                     | 
                                
                                    — | — | 
| Increase (decrease) through disposal of subsidiary, equity | 
                                        
                                             
                                                702,000
                                                
                                                    
                                                        BGN
                                                    
                                                
                                             
                                        
                                     | 
                                
                                    
                                        
                                             
                                                39,000
                                                
                                                    
                                                        BGN
                                                    
                                                
                                             
                                        
                                     | 
                                
                                    
                                        
                                             
                                                769,000
                                                
                                                    
                                                        BGN
                                                    
                                                
                                             
                                        
                                     | 
                                
                                    
                                        
                                             
                                                351,000
                                                
                                                    
                                                        BGN
                                                    
                                                
                                             
                                        
                                     | 
                                
                                    
                                        
                                             
                                                986,000
                                                
                                                    
                                                        BGN
                                                    
                                                
                                             
                                        
                                     | 
                                
                                    
                                        
                                             
                                                1 443
                                                
                                                    
                                                        BGN
                                                    
                                                
                                             
                                        
                                     | 
                                
                                    — | — | — | 
                                        
                                             
                                                284,000
                                                
                                                    
                                                        BGN
                                                    
                                                
                                             
                                        
                                     | 
                                
                                    — | 
| Increase (decrease) through transfer between revaluation surplus and retained earnings, equity | — | — | — | 
                                        
                                             
                                                90,000
                                                
                                                    
                                                        BGN
                                                    
                                                
                                             
                                        
                                     | 
                                
                                    — | 
                                        
                                             
                                                90,000
                                                
                                                    
                                                        BGN
                                                    
                                                
                                             
                                        
                                     | 
                                
                                    
                                        
                                             
                                                763,000
                                                
                                                    
                                                        BGN
                                                    
                                                
                                             
                                        
                                     | 
                                
                                    — | — | — | 
                                        
                                             
                                                763,000
                                                
                                                    
                                                        BGN
                                                    
                                                
                                             
                                        
                                     | 
                                
                            
| Increase (decrease) through appropriation of retained earnings, equity | — | 
                                        
                                             
                                                31,000
                                                
                                                    
                                                        BGN
                                                    
                                                
                                             
                                        
                                     | 
                                
                                    — | — | — | 
                                        
                                             
                                                31,000
                                                
                                                    
                                                        BGN
                                                    
                                                
                                             
                                        
                                     | 
                                
                                    — | — | — | — | — |