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] | |||
| Property, plant and equipment | 
                                                34,000
                                                
                                                    
                                                        BGN
                                                    
                                                
                                             | 
                                                9,000
                                                
                                                    
                                                        BGN
                                                    
                                                
                                             | — | 
| Intangible assets and goodwill [abstract] | |||
| Goodwill | 
                                                41,000
                                                
                                                    
                                                        BGN
                                                    
                                                
                                             | 
                                                -
                                                
                                                    
                                                        BGN
                                                    
                                                
                                             | — | 
| Investment property [abstract] | |||
| Investment property | 
                                                67 567
                                                
                                                    
                                                        BGN
                                                    
                                                
                                             | 
                                                56 134
                                                
                                                    
                                                        BGN
                                                    
                                                
                                             | — | 
| Investments in subsidiaries, joint ventures and associates reported in separate financial statements [abstract] | |||
| Investments in subsidiaries, joint ventures and associates reported in separate financial statements | 
                                                -
                                                
                                                    
                                                        BGN
                                                    
                                                
                                             | 
                                                13 545
                                                
                                                    
                                                        BGN
                                                    
                                                
                                             | — | 
| Trade and other current receivables [abstract] | |||
| Trade and other current receivables | 
                                                11 126
                                                
                                                    
                                                        BGN
                                                    
                                                
                                             | 
                                                14 461
                                                
                                                    
                                                        BGN
                                                    
                                                
                                             | — | 
| Classes of current inventories [abstract] | |||
| Other current inventories | 
                                                26,000
                                                
                                                    
                                                        BGN
                                                    
                                                
                                             | 
                                                16,000
                                                
                                                    
                                                        BGN
                                                    
                                                
                                             | — | 
| Current inventories | 
                                                5 334
                                                
                                                    
                                                        BGN
                                                    
                                                
                                             | 
                                                5 316
                                                
                                                    
                                                        BGN
                                                    
                                                
                                             | — | 
| Classes of current inventories, alternative [abstract] | |||
| Cash and cash equivalents [abstract] | |||
| Cash and cash equivalents | 
                                                915,000
                                                
                                                    
                                                        BGN
                                                    
                                                
                                             | 
                                                351,000
                                                
                                                    
                                                        BGN
                                                    
                                                
                                             | 
                                                355,000
                                                
                                                    
                                                        BGN
                                                    
                                                
                                             | 
| Classes of other provisions [abstract] | |||
| Other provisions [abstract] | |||
| Other current provisions | 
                                                2,000
                                                
                                                    
                                                        BGN
                                                    
                                                
                                             | 
                                                10,000
                                                
                                                    
                                                        BGN
                                                    
                                                
                                             | — | 
| Non-current portion of non-current borrowings, by type [abstract] | |||
| Non-current portion of non-current loans received | — | — | — | 
| Non-current portion of non-current secured bank loans received | 
                                                16 207
                                                
                                                    
                                                        BGN
                                                    
                                                
                                             | 
                                                18 214
                                                
                                                    
                                                        BGN
                                                    
                                                
                                             | — | 
| Non-current portion of non-current bonds issued | 
                                                1 956
                                                
                                                    
                                                        BGN
                                                    
                                                
                                             | 
                                                5 867
                                                
                                                    
                                                        BGN
                                                    
                                                
                                             | — | 
| Current borrowings and current portion of non-current borrowings, by type [abstract] | |||
| Current loans received and current portion of non-current loans received | — | — | — | 
| Current secured bank loans received and current portion of non-current secured bank loans received | 
                                                1 737
                                                
                                                    
                                                        BGN
                                                    
                                                
                                             | 
                                                2 866
                                                
                                                    
                                                        BGN
                                                    
                                                
                                             | — | 
| Current bonds issued and current portion of non-current bonds issued | 
                                                5 867
                                                
                                                    
                                                        BGN
                                                    
                                                
                                             | 
                                                3 912
                                                
                                                    
                                                        BGN
                                                    
                                                
                                             | — | 
| Other current borrowings and current portion of other non-current borrowings | 
                                                910,000
                                                
                                                    
                                                        BGN
                                                    
                                                
                                             | 
                                                891,000
                                                
                                                    
                                                        BGN
                                                    
                                                
                                             | — | 
| 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 advances received, representing current contract liabilities for performance obligations satisfied at point in time | 
                                                4 115
                                                
                                                    
                                                        BGN
                                                    
                                                
                                             | 
                                                10 800
                                                
                                                    
                                                        BGN
                                                    
                                                
                                             | — | 
| Trade and other current payables | 
                                                7 646
                                                
                                                    
                                                        BGN
                                                    
                                                
                                             | 
                                                435,000
                                                
                                                    
                                                        BGN
                                                    
                                                
                                             | — | 
| Issued capital [abstract] | |||
| Issued capital | 
                                                23 380
                                                
                                                    
                                                        BGN
                                                    
                                                
                                             | 
                                                23 380
                                                
                                                    
                                                        BGN
                                                    
                                                
                                             | — | 
| Retained earnings [abstract] | |||
| Retained earnings | 
                                                8 664
                                                
                                                    
                                                        BGN
                                                    
                                                
                                             | 
                                                8 919
                                                
                                                    
                                                        BGN
                                                    
                                                
                                             | — | 
| Accumulated other comprehensive income [abstract] | |||
| Revaluation surplus | 
                                                872,000
                                                
                                                    
                                                        BGN
                                                    
                                                
                                             | 
                                                872,000
                                                
                                                    
                                                        BGN
                                                    
                                                
                                             | — | 
| Net assets (liabilities) [abstract] | |||
| Assets | 
                                                85 044
                                                
                                                    
                                                        BGN
                                                    
                                                
                                             | 
                                                89 834
                                                
                                                    
                                                        BGN
                                                    
                                                
                                             | — | 
| Liabilities | 
                                                38 460
                                                
                                                    
                                                        BGN
                                                    
                                                
                                             | 
                                                42 995
                                                
                                                    
                                                        BGN
                                                    
                                                
                                             | — | 
| Net current assets (liabilities) [abstract] | |||
| Current assets | 
                                                17 401
                                                
                                                    
                                                        BGN
                                                    
                                                
                                             | 
                                                20 144
                                                
                                                    
                                                        BGN
                                                    
                                                
                                             | — | 
| Current liabilities | 
                                                20 277
                                                
                                                    
                                                        BGN
                                                    
                                                
                                             | 
                                                18 914
                                                
                                                    
                                                        BGN
                                                    
                                                
                                             | — | 
| Assets less current liabilities [abstract] |