XML 221 R200.htm IDEA: XBRL DOCUMENT
v3.21.1

28. OPERATING COSTS AND EXPENSES (Details 4) - BRL (R$) R$ in Millions | 12 Months Ended
--- | ---
Dec. 31, 2020 | Dec. 31, 2019 | Dec. 31, 2018
Disclosure of construction cost [abstract] |  |  |
Personnel and managers | R$ 83 | R$ 85 | R$ 70
Materials | 775 | 595 | 379
Outsourced services | 598 | 421 | 364
Others | 125 | 99 | 84
Construction cost | R$ 1,581 | R$ 1,200 | R$ 897

X
- Definition Construction contracts costs. + References No definition available. + Details
Name: | cig_ConstructionContractsCosts
Namespace Prefix: | cig_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Disclosure of construction cost. + References No definition available. + Details
Name: | cig_DisclosureOfConstructionCostAbstract
Namespace Prefix: | cig_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Material construction cost. + References No definition available. + Details
Name: | cig_MaterialConstructionCost
Namespace Prefix: | cig_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Other construction cost. + References No definition available. + Details
Name: | cig_OtherConstructionCost
Namespace Prefix: | cig_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Outsourced service cost. + References No definition available. + Details
Name: | cig_OutsourcedServiceCost
Namespace Prefix: | cig_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Personnel and managers cost. + References No definition available. + Details
Name: | cig_PersonnelAndManagersCost
Namespace Prefix: | cig_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration