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Schedule of financial instruments and fair value (Details) - BRL (R$) R$ in Millions | Dec. 31, 2021 | Dec. 31, 2020 | Dec. 31, 2019
--- | --- | --- | ---
IfrsStatementLineItems [Line Items] |  |  |
Assets | R$ 2,148 | R$ 4,058 |
Financial liabilities at amortised cost, class [member] |  |  |
IfrsStatementLineItems [Line Items] |  |  |
Assets | 12,042 | 9,693 |
Financial assets at fair value | 12,042 | 9,693 |
Financial liabilities | (15,293) | (18,872) |
Financial liabilities at fair value | (15,293) | (18,872) |
Financial liabilities at fair value through profit or loss, category [member] |  |  |
IfrsStatementLineItems [Line Items] |  |  |
Financial liabilities | (642) | (536) |
Financial liabilities at fair value | (642) | (536) |
Advances from clients [member] | Level 2 of fair value hierarchy [member] | Financial liabilities at amortised cost, class [member] |  |  |
IfrsStatementLineItems [Line Items] |  |  |
Financial liabilities | (11,364) | (15,020) |
Financial liabilities at fair value | (11,364) | (15,020) |
Debt With Pension Fund Forluz [Member] | Level 2 of fair value hierarchy [member] | Financial liabilities at amortised cost, class [member] |  |  |
IfrsStatementLineItems [Line Items] |  |  |
Financial liabilities | (385) | (473) |
Financial liabilities at fair value | (385) | (473) |
Solution for deficit of pension fund [member] | Level 2 of fair value hierarchy [member] | Financial liabilities at amortised cost, class [member] |  |  |
IfrsStatementLineItems [Line Items] |  |  |
Financial liabilities | (539) | (540) |
Financial liabilities at fair value | (539) | (540) |
Concessions Payable [member] | Level 3 of fair value hierarchy [member] | Financial liabilities at amortised cost, class [member] |  |  |
IfrsStatementLineItems [Line Items] |  |  |
Financial liabilities | (27) | (23) |
Financial liabilities at fair value | (27) | (23) |
Suppliers [member] | Level 2 of fair value hierarchy [member] | Financial liabilities at amortised cost, class [member] |  |  |
IfrsStatementLineItems [Line Items] |  |  |
Financial liabilities | (2,683) | (2,358) |
Financial liabilities at fair value | (2,683) | (2,358) |
Debentures [member] | Level 2 of fair value hierarchy [member] | Financial liabilities at amortised cost, class [member] |  |  |
IfrsStatementLineItems [Line Items] |  |  |
Financial liabilities | (244) | (227) |
Financial liabilities at fair value | (244) | (227) |
Sector Financial Liabilities [Member] | Level 2 of fair value hierarchy [member] | Financial liabilities at amortised cost, class [member] |  |  |
IfrsStatementLineItems [Line Items] |  |  |
Financial liabilities | (51) | (231) |
Financial liabilities at fair value | (51) | (231) |
Financial assets at amortised cost, class [member] | Securities cash investments one [member] | Level 2 of fair value hierarchy [member] |  |  |
IfrsStatementLineItems [Line Items] |  |  |
Assets | 1,095 | 1,214 |
Financial assets at fair value | 1,095 | 1,214 |
Financial assets at amortised cost, class [member] | Customers and traders concession holders transmission service [member] | Level 2 of fair value hierarchy [member] |  |  |
IfrsStatementLineItems [Line Items] |  |  |
Assets |  | 64 |
Financial assets at fair value | 4,482 | 4,534 |
Assets | 4,482 | 4,534 |
Financial assets at amortised cost, class [member] | Restricted cash [member] | Level 2 of fair value hierarchy [member] |  |  |
IfrsStatementLineItems [Line Items] |  |  |
Assets | 19 | 64 |
Financial assets at fair value | 19 |  |
Financial assets at amortised cost, class [member] | Restricted cash [member] | Level 2 of fair value hierarchy [member] | Restated 1 [Member] |  |  |
IfrsStatementLineItems [Line Items] |  |  |
Assets |  |  | R$ 12
Financial assets at fair value |  |  | R$ 12
Financial assets at amortised cost, class [member] | Accounts receivable from the State of Minas Gerais [member] | Level 2 of fair value hierarchy [member] |  |  |
IfrsStatementLineItems [Line Items] |  |  |
Assets | 13 |  |
Financial assets at fair value | 13 |  |
Financial assets at amortised cost, class [member] | Concession financial assets CVA Account and Other financial components in tariff adjustments [member] | Level 3 of fair value hierarchy [member] |  |  |
IfrsStatementLineItems [Line Items] |  |  |
Assets | 2,148 | 133 |
Financial assets at fair value | 2,148 | 133 |
Financial assets at amortised cost, class [member] | Reimbursement of tariff subsidy payments [member] | Level 2 of fair value hierarchy [member] |  |  |
IfrsStatementLineItems [Line Items] |  |  |
Assets | 291 | 88 |
Financial assets at fair value | 291 | 88 |
Financial assets at amortised cost, class [member] | Low income subsidy [member] | Level 2 of fair value hierarchy [member] |  |  |
IfrsStatementLineItems [Line Items] |  |  |
Assets | 47 | 43 |
Financial assets at fair value | 47 | 43 |
Financial assets at amortised cost, class [member] | Escrow deposits [member] | Level 2 of fair value hierarchy [member] |  |  |
IfrsStatementLineItems [Line Items] |  |  |
Assets | 1,155 | 1,056 |
Financial assets at fair value | 1,155 | 1,056 |
Financial assets at amortised cost, class [member] | Concession grant fee generation concessions [member] | Level 3 of fair value hierarchy [member] |  |  |
IfrsStatementLineItems [Line Items] |  |  |
Assets | 2,792 | 2,549 |
Financial assets at fair value | 2,792 | 2,549 |
Financial assets at fair value through profit or loss, category [member] |  |  |
IfrsStatementLineItems [Line Items] |  |  |
Assets | 16,487 | 18,518 |
Financial assets at fair value | 16,487 | 18,518 |
Financial assets at fair value through profit or loss, category [member] | Cash equivalents investments [member] |  |  |
IfrsStatementLineItems [Line Items] |  |  |
Assets | 708 | 1,587 |
Financial assets at fair value | 708 | 1,587 |
Financial assets at fair value through profit or loss, category [member] | Bank Certificates Of Deposit [Member] |  |  |
IfrsStatementLineItems [Line Items] |  |  |
Assets | 101 | 545 |
Financial assets at fair value | 101 | 545 |
Financial assets at fair value through profit or loss, category [member] | Treasury financial notes [member] | Level 1 of fair value hierarchy [member] |  |  |
IfrsStatementLineItems [Line Items] |  |  |
Assets | 178 | 731 |
Financial assets at fair value | 178 | 731 |
Financial assets at fair value through profit or loss, category [member] | Bank financial notes [member] | Level 2 of fair value hierarchy [member] |  |  |
IfrsStatementLineItems [Line Items] |  |  |
Assets | 705 | 1,635 |
Financial assets at fair value | 705 | 1,635 |
Marketable Securities [Member] |  |  |
IfrsStatementLineItems [Line Items] |  |  |
Assets | 1,692 | 4,498 |
Financial assets at fair value | 1,692 | 4,498 |
Derivative financial instruments [member] |  |  |
IfrsStatementLineItems [Line Items] |  |  |
Assets | 4,445 | 8,825 |
Financial assets at fair value | 4,445 | 8,825 |
Financial liabilities | (15,935) | (19,408) |
Financial liabilities at fair value | (15,935) | (19,408) |
Derivative financial instruments [member] | Derivative financial instrument assets, Swaps [member] | Level 3 of fair value hierarchy [member] |  |  |
IfrsStatementLineItems [Line Items] |  |  |
Assets | 1,219 | 2,949 |
Financial assets at fair value | 1,219 | 2,949 |
Derivative financial instruments [member] | Derivative financial instrument assets, Ativas and Sonda Put options [member] | Level 3 of fair value hierarchy [member] |  |  |
IfrsStatementLineItems [Line Items] |  |  |
Assets |  | 3 |
Financial assets at fair value |  | 3 |
Derivative financial instruments [member] | Concession of distribution infrastructure [member] | Level 3 of fair value hierarchy [member] |  |  |
IfrsStatementLineItems [Line Items] |  |  |
Assets | 718 | 559 |
Financial assets at fair value | 718 | 559 |
Derivative financial instruments [member] | Reimbursements receivable from generation [member] | Level 3 of fair value hierarchy [member] |  |  |
IfrsStatementLineItems [Line Items] |  |  |
Assets | 816 | 816 |
Financial assets at fair value | 816 | 816 |
Financial liabilities at fair value through profit or loss, category [member] | Derivative financial instrument assets, Swaps [member] | Level 3 of fair value hierarchy [member] |  |  |
IfrsStatementLineItems [Line Items] |  |  |
Financial liabilities | (6) |  |
Financial liabilities at fair value | (6) |  |
Financial liabilities at fair value through profit or loss, category [member] | Derivative Financial Instruments S A A G [Member] | Level 3 of fair value hierarchy [member] |  |  |
IfrsStatementLineItems [Line Items] |  |  |
Financial liabilities | (636) | (536) |
Financial liabilities at fair value | R$ (636) | R$ (536) |

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