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The amount of current financial assets. [Refer: Financial assets]

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

The amount of current financial liabilities. [Refer: Financial liabilities]

Name:	ifrs-full_CurrentFinancialLiabilities
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Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

The amount of assets that are: (a) cash; (b) an equity instrument of another entity; (c) a contractual right: (i) to receive cash or another financial asset from another entity; or (ii) to exchange financial assets or financial liabilities with another entity under conditions that are potentially favourable to the entity; or (d) a contract that will, or may be, settled in the entity’s own equity instruments and is: (i) a non-derivative for which the entity is, or may be, obliged to receive a variable number of the entity’s own equity instruments; or (ii) a derivative that will, or may be, settled other than by the exchange of a fixed amount of cash or another financial asset for a fixed number of the entity’s own equity instruments. For this purpose the entity’s own equity instruments do not include puttable financial instruments classified as equity instruments in accordance with paragraphs 16A-16B of IAS 32, instruments that impose on the entity an obligation to deliver to another party a pro rata share of the net assets of the entity only on liquidation and are classified as equity instruments in accordance with paragraphs 16C-16D of IAS 32, or instruments that are contracts for the future receipt or delivery of the entity’s own equity instruments. [Refer: Financial instruments, class [member]; Financial liabilities]

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Name IFRS
-Number 7
-IssueDate 2021-01-01
-Paragraph 25
-URI http://eifrs.ifrs.org/eifrs/xifrs-link?type=IFRS&num=7&code=ifrs-tx-2021-en-r&anchor=para_25&doctype=Standard
-URIDate 2021-03-24

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Name IFRS
-Number 7
-IssueDate 2021-01-01
-Paragraph 35H
-URI http://eifrs.ifrs.org/eifrs/xifrs-link?type=IFRS&num=7&code=ifrs-tx-2021-en-r&anchor=para_35H&doctype=Standard
-URIDate 2021-03-24

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Name IFRS
-Number 7
-IssueDate 2021-01-01
-Paragraph 35I
-URI http://eifrs.ifrs.org/eifrs/xifrs-link?type=IFRS&num=7&code=ifrs-tx-2021-en-r&anchor=para_35I&doctype=Standard
-URIDate 2021-03-24

Reference 4: http://www.xbrl.org/2003/role/disclosureRef
-Name IFRS
-Number 7
-IssueDate 2021-01-01
-Paragraph 35M
-URI http://eifrs.ifrs.org/eifrs/xifrs-link?type=IFRS&num=7&code=ifrs-tx-2021-en-r&anchor=para_35M&doctype=Standard
-URIDate 2021-03-24

Reference 5: http://www.xbrl.org/2003/role/exampleRef
-Name IFRS
-Number 7
-IssueDate 2021-01-01
-Paragraph 35N
-URI http://eifrs.ifrs.org/eifrs/xifrs-link?type=IFRS&num=7&code=ifrs-tx-2021-en-r&anchor=para_35N&doctype=Standard
-URIDate 2021-03-24

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

The amount of non-current financial assets. [Refer: Financial assets]

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Namespace Prefix:	ifrs-full_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

Name:	ifrs-full_TypesOfFinancialAssetsAxis=cig_AssetsRelatedToInfrastuctureMember
Namespace Prefix:
Data Type:	na
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Name:	ifrs-full_TypesOfFinancialAssetsAxis=cig_LiabilitiesRelatedToInfrastuctureMember
Namespace Prefix:
Data Type:	na
Balance Type:
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Name:	ifrs-full_ServiceConcessionArrangementsAxis=cig_DistributionsConcessionsMember
Namespace Prefix:
Data Type:	na
Balance Type:
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Name:	ifrs-full_ServiceConcessionArrangementsAxis=cig_GasConcessionsMember
Namespace Prefix:
Data Type:	na
Balance Type:
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Name:	ifrs-full_ServiceConcessionArrangementsAxis=cig_GenerationReceivableMember
Namespace Prefix:
Data Type:	na
Balance Type:
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Name:	ifrs-full_ServiceConcessionArrangementsAxis=cig_ConcessionGrantFeeMember
Namespace Prefix:
Data Type:	na
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