Advance payments to related party.

No definition available.

Name:	cig_AdvancePaymentsToRelatedParty
Namespace Prefix:	cig_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Represent information about the aggregate amounts of legal actions.

+ References

No definition available.

+ Details

Name:	cig_AggregateAmountsOfLegalActions
Namespace Prefix:	cig_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Represent information about the deliver contracted supply amount.

+ References

No definition available.

+ Details

Name:	cig_DeliverContractedSupplyAmount
Namespace Prefix:	cig_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Represent information about the description of contract interest rate.

+ References

No definition available.

+ Details

Name:	cig_DescriptionOfContractInterestRate
Namespace Prefix:	cig_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Represent information about the incourt reorganization loan amount.

+ References

No definition available.

+ Details

Name:	cig_IncourtReorganizationLoanAmount
Namespace Prefix:	cig_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Represent information about the loss on realization of receivables.

+ References

No definition available.

+ Details

Name:	cig_LossOnRealizationOfReceivables
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Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Represent information about the percentage of principal amount.

+ References

No definition available.

+ Details

Name:	cig_PercentageOfPrincipalAmount
Namespace Prefix:	cig_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Represent information about the public lighting contribution amount.

+ References

No definition available.

+ Details

Name:	cig_PublicLightingContributionAmount
Namespace Prefix:	cig_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Recognition of debits relating to supply of power.

+ References

No definition available.

+ Details

Name:	cig_RecognitionOfDebitsRelatingToSupplyOfPower
Namespace Prefix:	cig_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Related party transactions assets liabilities.

+ References

No definition available.

+ Details

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Namespace Prefix:	cig_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Line items represent concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes of the table.

+ References

No definition available.

+ Details

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Namespace Prefix:	ifrs-full_
Data Type:	xbrli:stringItemType
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Period Type:	duration

- Definition

The amount of outstanding commitments made by the entity in related party transactions. [Refer: Related parties [member]]

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Name IAS
-Number 24
-IssueDate 2019-01-01
-Paragraph 18
-Subparagraph b
-URI http://eifrs.ifrs.org/eifrs/xifrs-link?type=IAS&num=24&code=ifrs-tx-2019-en-r&anchor=para_18_b&doctype=Standard
-URIDate 2019-03-27

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Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

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- Details

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Data Type:	na
Balance Type:
Period Type:

- Details

Name:	ifrs-full_SignificantInvestmentsInSubsidiariesAxis=cig_SACarvalhoMember
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Data Type:	na
Balance Type:
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Data Type:	na
Balance Type:
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- Details

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Data Type:	na
Balance Type:
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- Details

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- Details

Name:	ifrs-full_CategoriesOfRelatedPartiesAxis=ifrs-full_JointControlOrSignificantInfluenceMember
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- Details

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32. RELATED PARTY TRANSACTIONS (Details Narrative) - BRL (R$) R$ in Millions			12 Months Ended
	Dec. 27, 2019	Nov. 25, 2019	Dec. 31, 2019	Dec. 31, 2017
Disclosure of transactions between related parties [line items]
Deliver contracted supply amount			R$ 40
Loss on realization of the receivables			R$ 688
In-court reorganization loan amount	R$ 65	R$ 10
Description of contract interest rate			The contracts specify interest equal to 100% of the accumulated variation in the DI rate, plus an annual spread, applied pro rata die (on 252-business-days basis), of 1.083% for the DIP contract and 2.5% for the DIP2 contract, up to the date of respective full payment.
Percentage of principal amount			120.00%
Eletrobras [Member]
Disclosure of transactions between related parties [line items]
Advance payments			R$ 70
Santo Antonio Energia [Member]
Disclosure of transactions between related parties [line items]
Advance payments			52
Sa Carvalho [Member]
Disclosure of transactions between related parties [line items]
Advance payments			12
Rosal [Member]
Disclosure of transactions between related parties [line items]
Advance payments			6
Related parties [Member]
Disclosure of transactions between related parties [line items]
Aggregate amounts of legal actions			98
Related parties [Member] \| Cemig D [Member]
Disclosure of transactions between related parties [line items]
Public lighting contribution amount			190
Due and unpaid payment of debits relating to supply of power				R$ 113
Related parties [Member] \| Cemig [Member]
Disclosure of transactions between related parties [line items]
Aggregate amounts of legal actions			32
Jointly-Controlled Entity [Member] \| Madeira Energia (Santo Antonio plant) [Member] \| Power Purchase Agreements [Member]
Disclosure of transactions between related parties [line items]
Reimbursement for decontracted supply			84
Outstanding amount			R$ 4