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Revenue - Schedule of Transmission Concession Contract (Details) - BRL (R$) R$ in Millions | 12 Months Ended
--- | ---
Dec. 31, 2023 | Dec. 31, 2022 | Dec. 31, 2021
Revenue [abstract] |  |  |
Construction and upgrades revenue | R$ 242 | R$ 407 | R$ 252
Construction and upgrades costs | (172) | (291) | (183)
Margin | R$ 70 | R$ 116 | R$ 69
Mark-up (%) | 40.70% | 39.86% | 37.40%
Operation and maintenance revenue | R$ 373 | R$ 413 | R$ 355
Operation and maintenance cost | (292) | (287) | (235)
Margin | R$ 81 | R$ 126 | R$ 120
Mark-up (%) | 27.74% | 43.90% | 50.88%

X
- Definition The amount of construction and upgrades costs. + References No definition available. + Details
Name: | cig_ConstructionAndUpgradesCosts
Namespace Prefix: | cig_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition The amount of construction and upgrades revenue. + References No definition available. + Details
Name: | cig_ConstructionAndUpgradesRevenue
Namespace Prefix: | cig_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition The amount of margin construction revenue. + References No definition available. + Details
Name: | cig_MarginConstructionRevenue
Namespace Prefix: | cig_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition The amount of margin operation revenue. + References No definition available. + Details
Name: | cig_MarginOperationRevenue
Namespace Prefix: | cig_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition The amount of markup construction revenue. + References No definition available. + Details
Name: | cig_MarkupConstructionRevenue
Namespace Prefix: | cig_
Data Type: | dtr-types:percentItemType
Balance Type: | na
Period Type: | duration

X
- Definition The amount of markup operation revenue. + References No definition available. + Details
Name: | cig_MarkupOperationRevenue
Namespace Prefix: | cig_
Data Type: | dtr-types:percentItemType
Balance Type: | na
Period Type: | duration

X
- Definition The amount of operation and maintenance cost. + References No definition available. + Details
Name: | cig_OperationAndMaintenanceCost
Namespace Prefix: | cig_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition The amount of operation and maintenance revenue. + References No definition available. + Details
Name: | cig_OperationAndMaintenanceRevenue
Namespace Prefix: | cig_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- References No definition available. + Details
Name: | ifrs-full_RevenueAbstract
Namespace Prefix: | ifrs-full_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration