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4. CONCESSIONS AND AUTHORIZATIONS (Details Narrative) - BRL (R$)
R$ in Millions
 1 Months Ended 12 Months Ended
Sep. 19, 2020
Dec. 31, 2020
Disclosure Of Electricity Concessions And Authorizations [line items]    
Discount of future payments 12.50%  
Concession grant fee R$ 852  
Dividend and interest on equity   25.00%
Cemig Distribution [member]    
Disclosure Of Electricity Concessions And Authorizations [line items]    
Concession expired   Dec. 31, 2045
Two Thousand and Nineteen [member]    
Disclosure Of Electricity Concessions And Authorizations [line items]    
Percentage of Selic rate   80.00%
Two Thousand Twenty [member]    
Disclosure Of Electricity Concessions And Authorizations [line items]    
Percentage of Selic rate   111.00%