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CONSOLIDATED STATEMENT OF CHANGES IN EQUITY (Parenthetical) - R$ / shares | 12 Months Ended
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Dec. 31, 2019 | Dec. 31, 2018 | Dec. 31, 2017
Statement of changes in equity [abstract] |  |  |
Statutory dividends per share | R$ 0.52 | R$ 0.59 | R$ 0.51

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- Definition Statutory dividend per share declared. + References No definition available. + Details
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Namespace Prefix: | cig_
Data Type: | num:perShareItemType
Balance Type: | na
Period Type: | duration

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