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10. INCOME AND SOCIAL CONTRIBUTION TAXES (Details 1) - BRL (R$) R$ in Millions | Dec. 31, 2020 | Dec. 31, 2019 | Jan. 02, 2019 | [1] | Dec. 31, 2018 | Dec. 31, 2017
--- | --- | --- | --- | --- | --- | ---
Disclosure Of Income And Social Contribution Taxes Recoverable [line items] |  |  |  |  |  |
Deferred tax assets | R$ 4,323 |  |  |  |  |
Deferred tax liabilities | (2,910) |  |  |  |  |
Total, net | 1,413 |  |  |  |  |
Total assets | 2,453 |  |  |  |  |
Total liabilities | (1,040) |  |  |  |  |
Revenues arising from transmission contract asset [member] |  |  |  |  |  |
Disclosure Of Income And Social Contribution Taxes Recoverable [line items] |  |  |  |  |  |
Deferred tax liabilities | (768) |  |  |  | R$ (768) |
Tax loss carryforwards [member] |  |  |  |  |  |
Disclosure Of Income And Social Contribution Taxes Recoverable [line items] |  |  |  |  |  |
Deferred tax assets | 401 |  |  |  |  |
Provisions for contingencies [member] |  |  |  |  |  |
Disclosure Of Income And Social Contribution Taxes Recoverable [line items] |  |  |  |  |  |
Deferred tax assets | 538 |  |  |  |  |
Impairment on investments [member] |  |  |  |  |  |
Disclosure Of Income And Social Contribution Taxes Recoverable [line items] |  |  |  |  |  |
Deferred tax assets | 640 |  |  |  |  |
Fair value of derivative financial instruments (PUT SAAG ) [member] |  |  |  |  |  |
Disclosure Of Income And Social Contribution Taxes Recoverable [line items] |  |  |  |  |  |
Deferred tax assets | 182 |  |  |  |  |
Post employment obligations [member] |  |  |  |  |  |
Disclosure Of Income And Social Contribution Taxes Recoverable [line items] |  |  |  |  |  |
Deferred tax assets | 2,168 |  |  |  |  |
Estimated provision for doubtful receivables [member] |  |  |  |  |  |
Disclosure Of Income And Social Contribution Taxes Recoverable [line items] |  |  |  |  |  |
Deferred tax assets | 256 |  |  |  |  |
Others [member] |  |  |  |  |  |
Disclosure Of Income And Social Contribution Taxes Recoverable [line items] |  |  |  |  |  |
Deferred tax assets | 138 |  |  |  |  |
Deferred tax liabilities | (7) |  |  |  |  |
Funding cost [member] |  |  |  |  |  |
Disclosure Of Income And Social Contribution Taxes Recoverable [line items] |  |  |  |  |  |
Deferred tax liabilities | (11) |  |  |  |  |
Deemed cost [member] |  |  |  |  |  |
Disclosure Of Income And Social Contribution Taxes Recoverable [line items] |  |  |  |  |  |
Deferred tax liabilities | (225) |  |  |  |  |
Acquisition costs of equity interests [member] |  |  |  |  |  |
Disclosure Of Income And Social Contribution Taxes Recoverable [line items] |  |  |  |  |  |
Deferred tax liabilities | (486) |  |  |  |  |
Borrowing costs capitalized [member] |  |  |  |  |  |
Disclosure Of Income And Social Contribution Taxes Recoverable [line items] |  |  |  |  |  |
Deferred tax liabilities | (169) |  |  |  |  |
Adjustment to expectation of cash flow concession assets [member] |  |  |  |  |  |
Disclosure Of Income And Social Contribution Taxes Recoverable [line items] |  |  |  |  |  |
Deferred tax liabilities | (242) |  |  |  |  |
Adjustment to fair value: swap/gains [member] |  |  |  |  |  |
Disclosure Of Income And Social Contribution Taxes Recoverable [line items] |  |  |  |  |  |
Deferred tax liabilities | (1,002) |  |  |  |  |
Restated [member] |  |  |  |  |  |
Disclosure Of Income And Social Contribution Taxes Recoverable [line items] |  |  |  |  |  |
Deferred tax assets |  | R$ 4,028 |  |  | 3,471 |
Deferred tax liabilities |  | (2,368) |  |  | (2,127) |
Total, net | R$ 1,413 | 1,660 |  |  | 1,344 | R$ 1,072
Total assets |  | 2,430 | [1] | R$ 2,147 | 2,147 |
Total liabilities |  | (770) | [1] | R$ (803) | (803) |
Restated [member] | Revenues arising from transmission contract asset [member] |  |  |  |  |  |
Disclosure Of Income And Social Contribution Taxes Recoverable [line items] |  |  |  |  |  |
Deferred tax liabilities |  | (624) |  |  | (627) |
Restated [member] | Tax loss carryforwards [member] |  |  |  |  |  |
Disclosure Of Income And Social Contribution Taxes Recoverable [line items] |  |  |  |  |  |
Deferred tax assets |  | 116 |  |  | 373 |
Restated [member] | Provisions for contingencies [member] |  |  |  |  |  |
Disclosure Of Income And Social Contribution Taxes Recoverable [line items] |  |  |  |  |  |
Deferred tax assets |  | 544 |  |  | 218 |
Restated [member] | Impairment on investments [member] |  |  |  |  |  |
Disclosure Of Income And Social Contribution Taxes Recoverable [line items] |  |  |  |  |  |
Deferred tax assets |  | 660 |  |  | 882 |
Restated [member] | Fair value of derivative financial instruments (PUT SAAG ) [member] |  |  |  |  |  |
Disclosure Of Income And Social Contribution Taxes Recoverable [line items] |  |  |  |  |  |
Deferred tax assets |  | 164 |  |  | 143 |
Restated [member] | Post employment obligations [member] |  |  |  |  |  |
Disclosure Of Income And Social Contribution Taxes Recoverable [line items] |  |  |  |  |  |
Deferred tax assets |  | 2,090 |  |  | 1,477 |
Restated [member] | Estimated provision for doubtful receivables [member] |  |  |  |  |  |
Disclosure Of Income And Social Contribution Taxes Recoverable [line items] |  |  |  |  |  |
Deferred tax assets |  | 283 |  |  | 279 |
Restated [member] | Others [member] |  |  |  |  |  |
Disclosure Of Income And Social Contribution Taxes Recoverable [line items] |  |  |  |  |  |
Deferred tax assets |  | 171 |  |  | 99 |
Deferred tax liabilities |  | (5) |  |  | (38) |
Restated [member] | Funding cost [member] |  |  |  |  |  |
Disclosure Of Income And Social Contribution Taxes Recoverable [line items] |  |  |  |  |  |
Deferred tax liabilities |  | (16) |  |  | (25) |
Restated [member] | Deemed cost [member] |  |  |  |  |  |
Disclosure Of Income And Social Contribution Taxes Recoverable [line items] |  |  |  |  |  |
Deferred tax liabilities |  | (232) |  |  | (239) |
Restated [member] | Acquisition costs of equity interests [member] |  |  |  |  |  |
Disclosure Of Income And Social Contribution Taxes Recoverable [line items] |  |  |  |  |  |
Deferred tax liabilities |  | (503) |  |  | (501) |
Restated [member] | Borrowing costs capitalized [member] |  |  |  |  |  |
Disclosure Of Income And Social Contribution Taxes Recoverable [line items] |  |  |  |  |  |
Deferred tax liabilities |  | (166) |  |  | (168) |
Restated [member] | Adjustment to expectation of cash flow concession assets [member] |  |  |  |  |  |
Disclosure Of Income And Social Contribution Taxes Recoverable [line items] |  |  |  |  |  |
Deferred tax liabilities |  | (247) |  |  | (252) |
Restated [member] | Adjustment to fair value: swap/gains [member] |  |  |  |  |  |
Disclosure Of Income And Social Contribution Taxes Recoverable [line items] |  |  |  |  |  |
Deferred tax liabilities |  | R$ (575) |  |  | R$ (277) |
[1] | For further details of restatement of comparative balances, see Note 2.8

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