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31. FINANCIAL INSTRUMENTS AND RISK MANAGEMENT (Details) - BRL (R$) R$ in Millions | Dec. 31, 2020 | Dec. 31, 2019 | Dec. 31, 2018
--- | --- | --- | ---
Disclosure of detailed information about financial instruments [line items] |  |  |  |
Assets |  | R$ 4,058 |  |
Financial liabilities |  |  | R$ 18,764 |
Financial liabilities at amortised cost, class [member] |  |  |  |
Disclosure of detailed information about financial instruments [line items] |  |  |  |
Assets | [1] | 9,693 |  |
Financial assets at fair value | [1] | 9,693 |  |
Financial liabilities | [1] | (18,872) |  |
Financial liabilities at fair value | [1] | (18,872) |  |
Financial liabilities at fair value through profit or loss, category [member] |  |  |  |
Disclosure of detailed information about financial instruments [line items] |  |  |  |
Financial liabilities | [1] | (536) |  |
Financial liabilities at fair value | [1] | (536) |  |
Loans, financing and debentures [member] | Level 2 [member] | Financial liabilities at amortised cost, class [member] |  |  |  |
Disclosure of detailed information about financial instruments [line items] |  |  |  |
Financial liabilities | [1] | (15,020) |  |
Financial liabilities at fair value | [1] | (15,020) |  |
Debt with pension fund (forluz) [member] | Level 2 [member] | Financial liabilities at amortised cost, class [member] |  |  |  |
Disclosure of detailed information about financial instruments [line items] |  |  |  |
Financial liabilities | [1] | (473) |  |
Financial liabilities at fair value | [1] | (473) |  |
Deficit of pension fund (forluz) [member] | Level 2 [member] | Financial liabilities at amortised cost, class [member] |  |  |  |
Disclosure of detailed information about financial instruments [line items] |  |  |  |
Financial liabilities | [1] | (540) |  |
Financial liabilities at fair value | [1] | (540) |  |
Concessions payable [member] | Level 3 [member] | Financial liabilities at amortised cost, class [member] |  |  |  |
Disclosure of detailed information about financial instruments [line items] |  |  |  |
Financial liabilities | [1] | (23) |  |
Financial liabilities at fair value | [1] | (23) |  |
Suppliers [member] | Level 2 [member] | Financial liabilities at amortised cost, class [member] |  |  |  |
Disclosure of detailed information about financial instruments [line items] |  |  |  |
Financial liabilities | [1] | (2,358) |  |
Financial liabilities at fair value | [1] | (2,358) |  |
Leasing transactions [member] | Level 2 [member] | Financial liabilities at amortised cost, class [member] |  |  |  |
Disclosure of detailed information about financial instruments [line items] |  |  |  |
Financial liabilities | [1] | (227) |  |
Financial liabilities at fair value | [1] | (227) |  |
Sector financial liabilities [member] | Level 2 [member] | Financial liabilities at amortised cost, class [member] |  |  |  |
Disclosure of detailed information about financial instruments [line items] |  |  |  |
Financial liabilities | [1] | (231) |  |
Financial liabilities at fair value | [1] | (231) |  |
Restated [member] |  |  |  |
Disclosure of detailed information about financial instruments [line items] |  |  |  |
Assets |  |  | 4,650 | R$ 4,702
Restated [member] | Financial liabilities at amortised cost, class [member] |  |  |  |
Disclosure of detailed information about financial instruments [line items] |  |  |  |
Assets | [1] |  | 10,847 |
Financial assets at fair value | [1] |  | 10,847 |
Financial liabilities | [1] |  | (18,281) |
Financial liabilities at fair value | [1] |  | (18,281) |
Restated [member] | Financial liabilities at fair value through profit or loss, category [member] |  |  |  |
Disclosure of detailed information about financial instruments [line items] |  |  |  |
Financial liabilities | [1] |  | (483) |
Financial liabilities at fair value | [1] |  | (483) |
Restated [member] | Loans, financing and debentures [member] | Level 2 [member] | Financial liabilities at amortised cost, class [member] |  |  |  |
Disclosure of detailed information about financial instruments [line items] |  |  |  |
Financial liabilities | [1] |  | (14,777) |
Financial liabilities at fair value | [1] |  | (14,777) |
Restated [member] | Debt with pension fund (forluz) [member] | Level 2 [member] | Financial liabilities at amortised cost, class [member] |  |  |  |
Disclosure of detailed information about financial instruments [line items] |  |  |  |
Financial liabilities | [1] |  | (566) |
Financial liabilities at fair value | [1] |  | (566) |
Restated [member] | Deficit of pension fund (forluz) [member] | Level 2 [member] | Financial liabilities at amortised cost, class [member] |  |  |  |
Disclosure of detailed information about financial instruments [line items] |  |  |  |
Financial liabilities | [1] |  | (550) |
Financial liabilities at fair value | [1] |  | (550) |
Restated [member] | Concessions payable [member] | Level 3 [member] | Financial liabilities at amortised cost, class [member] |  |  |  |
Disclosure of detailed information about financial instruments [line items] |  |  |  |
Financial liabilities | [1] |  | (20) |
Financial liabilities at fair value | [1] |  | (20) |
Restated [member] | Leasing transactions [member] | Level 2 [member] | Financial liabilities at amortised cost, class [member] |  |  |  |
Disclosure of detailed information about financial instruments [line items] |  |  |  |
Financial liabilities | [1] |  | (288) |
Financial liabilities at fair value | [1] |  | (288) |
Restated [member] | Sector financial liabilities [member] | Level 2 [member] | Financial liabilities at amortised cost, class [member] |  |  |  |
Disclosure of detailed information about financial instruments [line items] |  |  |  |
Financial liabilities | [1] |  |  |
Financial liabilities at fair value | [1] |  |  |
Derivative financial instruments [member] |  |  |  |
Disclosure of detailed information about financial instruments [line items] |  |  |  |
Assets |  | 8,825 |  |
Financial assets at fair value |  | 8,825 |  |
Financial liabilities |  | (19,408) |  |
Financial liabilities at fair value |  | (19,408) |  |
Derivative financial instruments [member] | Indemnifiable receivable generation [member] | Level 3 [member] |  |  |  |
Disclosure of detailed information about financial instruments [line items] |  |  |  |
Assets |  | 816 |  |
Financial assets at fair value |  | 816 |  |
Derivative financial instruments [member] | Concession financial assets - distribution infrastructure [member] | Level 3 [member] |  |  |  |
Disclosure of detailed information about financial instruments [line items] |  |  |  |
Assets |  | 559 |  |
Financial assets at fair value |  | 559 |  |
Derivative financial instruments [member] | Derivative financial instrument assets, ativas and sonda put options [member] | Level 3 [member] |  |  |  |
Disclosure of detailed information about financial instruments [line items] |  |  |  |
Assets |  | 3 |  |
Financial assets at fair value |  | 3 |  |
Derivative financial instruments [member] | Derivative financial instrument assets, swaps [member] | Level 3 [member] |  |  |  |
Disclosure of detailed information about financial instruments [line items] |  |  |  |
Assets |  | 2,949 |  |
Financial assets at fair value |  | 2,949 |  |
Derivative financial instruments [member] | Restated [member] |  |  |  |
Disclosure of detailed information about financial instruments [line items] |  |  |  |
Assets |  |  | 3,971 |
Financial assets at fair value |  |  | 3,971 |
Financial liabilities |  |  | (18,764) |
Financial liabilities at fair value |  |  | (18,764) |
Derivative financial instruments [member] | Restated [member] | Indemnifiable receivable generation [member] | Level 3 [member] |  |  |  |
Disclosure of detailed information about financial instruments [line items] |  |  |  |
Assets |  |  | 816 |
Financial assets at fair value |  |  | 816 |
Derivative financial instruments [member] | Restated [member] | Concession financial assets - distribution infrastructure [member] | Level 3 [member] |  |  |  |
Disclosure of detailed information about financial instruments [line items] |  |  |  |
Assets |  |  | 484 |
Financial assets at fair value |  |  | 484 |
Derivative financial instruments [member] | Restated [member] | Derivative financial instrument assets, ativas and sonda put options [member] | Level 3 [member] |  |  |  |
Disclosure of detailed information about financial instruments [line items] |  |  |  |
Assets |  |  | 3 |
Financial assets at fair value |  |  | 3 |
Derivative financial instruments [member] | Restated [member] | Derivative financial instrument assets, swaps [member] | Level 3 [member] |  |  |  |
Disclosure of detailed information about financial instruments [line items] |  |  |  |
Assets |  |  | 1,691 |
Financial assets at fair value |  |  | 1,691 |
Financial assets at amortised cost, class [member] | Concession grant fee generation concessions [member] | Level 3 [member] |  |  |  |
Disclosure of detailed information about financial instruments [line items] |  |  |  |
Assets | [1] | 2,549 |  |
Financial assets at fair value | [1] | 2,549 |  |
Financial assets at amortised cost, class [member] | Escrow deposits [member] | Level 2 [member] |  |  |  |
Disclosure of detailed information about financial instruments [line items] |  |  |  |
Assets | [1] | 1,056 |  |
Financial assets at fair value | [1] | 1,056 |  |
Financial assets at amortised cost, class [member] | Low income subsidy [member] | Level 2 [member] |  |  |  |
Disclosure of detailed information about financial instruments [line items] |  |  |  |
Assets | [1] | 43 |  |
Financial assets at fair value | [1] | 43 |  |
Financial assets at amortised cost, class [member] | Reimbursement of tariff subsidy [member] | Level 2 [member] |  |  |  |
Disclosure of detailed information about financial instruments [line items] |  |  |  |
Assets | [1] | 88 |  |
Financial assets at fair value | [1] | 88 |  |
Financial assets at amortised cost, class [member] | Concession financial assets CVA account and other financial components in tariff adjustments [member] | Level 3 [member] |  |  |  |
Disclosure of detailed information about financial instruments [line items] |  |  |  |
Assets | [1] | 133 |  |
Financial assets at fair value | [1] | 133 |  |
Financial assets at amortised cost, class [member] | Restricted cash [member] | Level 2 [member] |  |  |  |
Disclosure of detailed information about financial instruments [line items] |  |  |  |
Assets | [1] | 64 |  |
Financial assets at fair value | [1] | 64 |  |
Financial assets at amortised cost, class [member] | Accounts receivable from customers and traders concession holders (transmission service) [member] | Level 2 [member] |  |  |  |
Disclosure of detailed information about financial instruments [line items] |  |  |  |
Assets | [1] | 4,534 |  |
Financial assets at fair value | [1] | 4,534 |  |
Financial assets at amortised cost, class [member] | Accounts receivable from the state of minas gerais [member] | Level 2 [member] |  |  |  |
Disclosure of detailed information about financial instruments [line items] |  |  |  |
Assets | [1] | 12 |  |
Financial assets at fair value | [1] | 12 |  |
Financial assets at amortised cost, class [member] | Marketable securities - cash investments [member] | Level 2 [member] |  |  |  |
Disclosure of detailed information about financial instruments [line items] |  |  |  |
Assets | [1] | 1,214 |  |
Financial assets at fair value | [1] | 1,214 |  |
Financial assets at amortised cost, class [member] | Restated [member] | Concession grant fee generation concessions [member] | Level 3 [member] |  |  |  |
Disclosure of detailed information about financial instruments [line items] |  |  |  |
Assets | [1] |  | 2,468 |
Financial assets at fair value | [1] |  | 2,468 |
Financial assets at amortised cost, class [member] | Restated [member] | Escrow deposits [member] | Level 2 [member] |  |  |  |
Disclosure of detailed information about financial instruments [line items] |  |  |  |
Assets | [1] |  | 2,540 |
Financial assets at fair value | [1] |  | 2,540 |
Financial assets at amortised cost, class [member] | Restated [member] | Low income subsidy [member] | Level 2 [member] |  |  |  |
Disclosure of detailed information about financial instruments [line items] |  |  |  |
Assets | [1] |  | 30 |
Financial assets at fair value | [1] |  | 30 |
Financial assets at amortised cost, class [member] | Restated [member] | Reimbursement of tariff subsidy [member] | Level 2 [member] |  |  |  |
Disclosure of detailed information about financial instruments [line items] |  |  |  |
Assets | [1] |  | 97 |
Financial assets at fair value | [1] |  | 97 |
Financial assets at amortised cost, class [member] | Restated [member] | Concession financial assets CVA account and other financial components in tariff adjustments [member] | Level 3 [member] |  |  |  |
Disclosure of detailed information about financial instruments [line items] |  |  |  |
Assets | [1] |  | 882 |
Financial assets at fair value | [1] |  | 882 |
Financial assets at amortised cost, class [member] | Restated [member] | Restricted cash [member] | Level 2 [member] |  |  |  |
Disclosure of detailed information about financial instruments [line items] |  |  |  |
Assets | [1] |  | 12 |
Financial assets at fair value | [1] |  | 12 |
Financial assets at amortised cost, class [member] | Restated [member] | Accounts receivable from customers and traders concession holders (transmission service) [member] | Level 2 [member] |  |  |  |
Disclosure of detailed information about financial instruments [line items] |  |  |  |
Assets | [1] |  | 4,601 |
Financial assets at fair value | [1] |  | 4,601 |
Financial assets at amortised cost, class [member] | Restated [member] | Accounts receivable from the state of minas gerais [member] | Level 2 [member] |  |  |  |
Disclosure of detailed information about financial instruments [line items] |  |  |  |
Assets | [1] |  | 115 |
Financial assets at fair value | [1] |  | 115 |
Financial assets at amortised cost, class [member] | Restated [member] | Marketable securities - cash investments [member] | Level 2 [member] |  |  |  |
Disclosure of detailed information about financial instruments [line items] |  |  |  |
Assets | [1] |  | 102 |
Financial assets at fair value | [1] |  | 102 |
Financial assets at amortised cost, class [member] | Restated [member] | Suppliers [member] | Level 2 [member] |  |  |  |
Disclosure of detailed information about financial instruments [line items] |  |  |  |
Financial liabilities | [1] |  | (2,080) |
Financial liabilities at fair value | [1] |  | (2,080) |
Financial assets at fair value through profit or loss, category [member] |  |  |  |
Disclosure of detailed information about financial instruments [line items] |  |  |  |
Assets |  | 18,518 |  |
Financial assets at fair value |  | 18,518 |  |
Financial assets at fair value through profit or loss, category [member] | Marketable securities - bank financial notes [member] | Level 2 [member] |  |  |  |
Disclosure of detailed information about financial instruments [line items] |  |  |  |
Assets |  | 1,635 |  |
Financial assets at fair value |  | 1,635 |  |
Financial assets at fair value through profit or loss, category [member] | Marketable securities - treasury financial notes [member] | Level 1 [member] |  |  |  |
Disclosure of detailed information about financial instruments [line items] |  |  |  |
Assets |  | 731 |  |
Financial assets at fair value |  | 731 |  |
Financial assets at fair value through profit or loss, category [member] | Marketable securities - bank certificates of deposit (CDBs) [member] |  |  |  |
Disclosure of detailed information about financial instruments [line items] |  |  |  |
Assets |  | 545 |  |
Financial assets at fair value |  | 545 |  |
Financial assets at fair value through profit or loss, category [member] | Cash equivalents investments [member] |  |  |  |
Disclosure of detailed information about financial instruments [line items] |  |  |  |
Assets |  | 1,587 |  |
Financial assets at fair value |  | 1,587 |  |
Financial assets at fair value through profit or loss, category [member] | Restated [member] |  |  |  |
Disclosure of detailed information about financial instruments [line items] |  |  |  |
Assets |  |  | 14,818 |
Financial assets at fair value |  |  | 14,818 |
Financial assets at fair value through profit or loss, category [member] | Restated [member] | Marketable securities - bank financial notes [member] | Level 2 [member] |  |  |  |
Disclosure of detailed information about financial instruments [line items] |  |  |  |
Assets |  |  | 557 |
Financial assets at fair value |  |  | 557 |
Financial assets at fair value through profit or loss, category [member] | Restated [member] | Marketable securities - treasury financial notes [member] | Level 1 [member] |  |  |  |
Disclosure of detailed information about financial instruments [line items] |  |  |  |
Assets |  |  | 94 |
Financial assets at fair value |  |  | 94 |
Financial assets at fair value through profit or loss, category [member] | Restated [member] | Marketable securities - bank certificates of deposit (CDBs) [member] |  |  |  |
Disclosure of detailed information about financial instruments [line items] |  |  |  |
Assets |  |  |  |
Financial assets at fair value |  |  |  |
Financial assets at fair value through profit or loss, category [member] | Restated [member] | Cash equivalents investments [member] |  |  |  |
Disclosure of detailed information about financial instruments [line items] |  |  |  |
Assets |  |  | 326 |
Financial assets at fair value |  |  | 326 |
Marketable securities [member] |  |  |  |
Disclosure of detailed information about financial instruments [line items] |  |  |  |
Assets |  | 4,498 |  |
Financial assets at fair value |  | 4,498 |  |
Marketable securities [member] | Restated [member] |  |  |  |
Disclosure of detailed information about financial instruments [line items] |  |  |  |
Assets |  |  | 977 |
Financial assets at fair value |  |  | 977 |
Financial liabilities at fair value through profit or loss, category [member] | Derivative financial instruments (SAAG put options) [member] | Level 3 [member] |  |  |  |
Disclosure of detailed information about financial instruments [line items] |  |  |  |
Financial liabilities |  | (536) |  |
Financial liabilities at fair value |  | (536) |  |
Financial liabilities at fair value through profit or loss, category [member] | Restated [member] | Derivative financial instruments (SAAG put options) [member] | Level 3 [member] |  |  |  |
Disclosure of detailed information about financial instruments [line items] |  |  |  |
Financial liabilities |  |  | (483) |
Financial liabilities at fair value |  |  | (483) |
Financial assets at fair value through profit or loss, category [member] |  |  |  |
Disclosure of detailed information about financial instruments [line items] |  |  |  |
Assets |  | 4,498 |  |
Financial assets at fair value |  | R$ 4,498 |  |
Financial assets at fair value through profit or loss, category [member] | Restated [member] |  |  |  |
Disclosure of detailed information about financial instruments [line items] |  |  |  |
Assets |  |  | 977 |
Financial assets at fair value |  |  | R$ 977 |
[1] | On December 31, 2020 and 2019, the book values of financial instruments reflect their fair values.

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- Definition 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] + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Name IFRS -Number 7 -IssueDate 2020-01-01 -Paragraph 25 -URI http://eifrs.ifrs.org/eifrs/xifrs-link?type=IFRS&num=7&code=ifrs-tx-2020-en-r&anchor=para_25&doctype=Standard -URIDate 2020-01-01 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Name IFRS -Number 7 -IssueDate 2020-01-01 -Paragraph 35H -URI http://eifrs.ifrs.org/eifrs/xifrs-link?type=IFRS&num=7&code=ifrs-tx-2020-en-r&anchor=para_35H&doctype=Standard -URIDate 2020-01-01 Reference 3: http://www.xbrl.org/2003/role/disclosureRef -Name IFRS -Number 7 -IssueDate 2020-01-01 -Paragraph 35I -URI http://eifrs.ifrs.org/eifrs/xifrs-link?type=IFRS&num=7&code=ifrs-tx-2020-en-r&anchor=para_35I&doctype=Standard -URIDate 2020-01-01 Reference 4: http://www.xbrl.org/2003/role/disclosureRef -Name IFRS -Number 7 -IssueDate 2020-01-01 -Paragraph 35M -URI http://eifrs.ifrs.org/eifrs/xifrs-link?type=IFRS&num=7&code=ifrs-tx-2020-en-r&anchor=para_35M&doctype=Standard -URIDate 2020-01-01 Reference 5: http://www.xbrl.org/2003/role/exampleRef -Name IFRS -Number 7 -IssueDate 2020-01-01 -Paragraph 35N -URI http://eifrs.ifrs.org/eifrs/xifrs-link?type=IFRS&num=7&code=ifrs-tx-2020-en-r&anchor=para_35N&doctype=Standard -URIDate 2020-01-01 + Details
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- Definition The amount of liabilities that are: (a) a contractual obligation: (i) to deliver cash or another financial asset to another entity; or (ii) to exchange financial assets or financial liabilities with another entity under conditions that are potentially unfavourable to the entity; or (b) 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 deliver 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, rights, options or warrants to acquire a fixed number of the entity’s own equity instruments for a fixed amount of any currency are equity instruments if the entity offers the rights, options or warrants pro rata to all of its existing owners of the same class of its own non-derivative equity instruments. Also, for those purposes the entity’s own equity instruments do not include puttable financial instruments that are 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. As an exception, an instrument that meets the definition of a financial liability is classified as an equity instrument if it has all the features and meets the conditions in paragraphs 16A-16B or paragraphs 16C-16D of IAS 32. [Refer: Financial instruments, class [member]; Financial assets; Derivatives [member]] + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Name IFRS -Number 7 -IssueDate 2020-01-01 -Paragraph 25 -URI http://eifrs.ifrs.org/eifrs/xifrs-link?type=IFRS&num=7&code=ifrs-tx-2020-en-r&anchor=para_25&doctype=Standard -URIDate 2020-01-01 + Details
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