Statement Of Cash Flows [Abstract]
| Concept | As at 2021-12-31 | 2021-01-01 to 2021-12-31 | As at 2020-12-31 | 2020-01-01 to 2020-12-31 | As at 2019-12-31 | 
|---|---|---|---|---|---|
| Statement of cash flows [abstract] | |||||
| Cash flows from (used in) operating activities [abstract] | |||||
| Classes of cash receipts from operating activities [abstract] | |||||
| Receipts from sales of goods and rendering of services | — | 
                                                5 480
                                                
                                                    
                                                        BGN
                                                    
                                                
                                             | — | 
                                                4 593
                                                
                                                    
                                                        BGN
                                                    
                                                
                                             | — | 
| Classes of cash payments from operating activities [abstract] | |||||
| Payments to suppliers for goods and services | — | 
                                                3 657
                                                
                                                    
                                                        BGN
                                                    
                                                
                                             | — | 
                                                2 331
                                                
                                                    
                                                        BGN
                                                    
                                                
                                             | — | 
| Payments to and on behalf of employees | — | 
                                                2 150
                                                
                                                    
                                                        BGN
                                                    
                                                
                                             | — | 
                                                1 881
                                                
                                                    
                                                        BGN
                                                    
                                                
                                             | — | 
| Other inflows (outflows) of cash, classified as operating activities | — | 
                                                38,000
                                                
                                                    
                                                        BGN
                                                    
                                                
                                             | — | 
                                                191,000
                                                
                                                    
                                                        BGN
                                                    
                                                
                                             | — | 
| Cash flows from (used in) operating activities | — | 
                                                1 456
                                                
                                                    
                                                        BGN
                                                    
                                                
                                             | — | 
                                                644,000
                                                
                                                    
                                                        BGN
                                                    
                                                
                                             | — | 
| Cash flows from (used in) investing activities [abstract] | |||||
| Proceeds from sales of property, plant and equipment, classified as investing activities | — | 
                                                -
                                                
                                                    
                                                        BGN
                                                    
                                                
                                             | — | 
                                                5,000
                                                
                                                    
                                                        BGN
                                                    
                                                
                                             | — | 
| Purchase of property, plant and equipment, classified as investing activities | — | 
                                                76,000
                                                
                                                    
                                                        BGN
                                                    
                                                
                                             | — | 
                                                27,000
                                                
                                                    
                                                        BGN
                                                    
                                                
                                             | — | 
| Cash flows from (used in) investing activities | — | 
                                                6 016
                                                
                                                    
                                                        BGN
                                                    
                                                
                                             | — | 
                                                22,000
                                                
                                                    
                                                        BGN
                                                    
                                                
                                             | — | 
| Cash flows from (used in) financing activities [abstract] | |||||
| Proceeds from borrowings, classified as financing activities | — | 
                                                635,000
                                                
                                                    
                                                        BGN
                                                    
                                                
                                             | — | 
                                                37,000
                                                
                                                    
                                                        BGN
                                                    
                                                
                                             | — | 
| Repayments of borrowings, classified as financing activities | — | 
                                                696,000
                                                
                                                    
                                                        BGN
                                                    
                                                
                                             | — | 
                                                96,000
                                                
                                                    
                                                        BGN
                                                    
                                                
                                             | — | 
| Payments of lease liabilities, classified as financing activities | — | 
                                                65,000
                                                
                                                    
                                                        BGN
                                                    
                                                
                                             | — | 
                                                70,000
                                                
                                                    
                                                        BGN
                                                    
                                                
                                             | — | 
| Dividends paid, classified as financing activities | — | 
                                                1 436
                                                
                                                    
                                                        BGN
                                                    
                                                
                                             | — | 
                                                -
                                                
                                                    
                                                        BGN
                                                    
                                                
                                             | — | 
| Interest paid, classified as financing activities | — | 
                                                10,000
                                                
                                                    
                                                        BGN
                                                    
                                                
                                             | — | 
                                                11,000
                                                
                                                    
                                                        BGN
                                                    
                                                
                                             | — | 
| Cash flows from (used in) financing activities | — | 
                                                1 572
                                                
                                                    
                                                        BGN
                                                    
                                                
                                             | — | 
                                                140,000
                                                
                                                    
                                                        BGN
                                                    
                                                
                                             | — | 
| Increase (decrease) in cash and cash equivalents after effect of exchange rate changes | — | 
                                                2 988
                                                
                                                    
                                                        BGN
                                                    
                                                
                                             | — | 
                                                482,000
                                                
                                                    
                                                        BGN
                                                    
                                                
                                             | — | 
| Cash and cash equivalents | 
                                                3 892
                                                
                                                    
                                                        BGN
                                                    
                                                
                                             | — | 
                                                862,000
                                                
                                                    
                                                        BGN
                                                    
                                                
                                             | — | 
                                                412,000
                                                
                                                    
                                                        BGN
                                                    
                                                
                                             |