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30. OPERATING COSTS AND EXPENSES (Details 2) - BRL (R$) R$ in Millions | 12 Months Ended
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Dec. 31, 2019 | Dec. 31, 2018 | Dec. 31, 2017
Disclosure Of Operating Costs And Expenses [line items] |  |  |
Energy purchased for resale | R$ 11,286 | R$ 11,084 | R$ 10,919
Free Market [Member] |  |  |
Disclosure Of Operating Costs And Expenses [line items] |  |  |
Energy purchased for resale | 4,098 | 3,871 | 4,283
Proinfa Program [Member] |  |  |
Disclosure Of Operating Costs And Expenses [line items] |  |  |
Energy purchased for resale | 376 | 324 | 303
Physical Guarantee Quota Contracts [Member] |  |  |
Disclosure Of Operating Costs And Expenses [line items] |  |  |
Energy purchased for resale | 715 | 679 | 461
Regulated Market Auctions [Member] |  |  |
Disclosure Of Operating Costs And Expenses [line items] |  |  |
Energy purchased for resale | 3,021 | 3,346 | 3,555
Bilateral Contracts [Member] |  |  |
Disclosure Of Operating Costs And Expenses [line items] |  |  |
Energy purchased for resale | 311 | 484 | 385
Angra I And II Nuclear Plants [Member] |  |  |
Disclosure Of Operating Costs And Expenses [line items] |  |  |
Energy purchased for resale | 269 | 267 | 244
Pasep and Cofins Credits [Member] |  |  |
Disclosure Of Operating Costs And Expenses [line items] |  |  |
Energy purchased for resale | (1,026) | (1,056) | (1,053)
Itaipu Binacional [Member] |  |  |
Disclosure Of Operating Costs And Expenses [line items] |  |  |
Energy purchased for resale | 1,429 | 1,351 | 1,243
Spot Market [Member] |  |  |
Disclosure Of Operating Costs And Expenses [line items] |  |  |
Energy purchased for resale | 1,886 | R$ 1,818 | R$ 1,498
Distributed Generation [member] |  |  |
Disclosure Of Operating Costs And Expenses [line items] |  |  |
Energy purchased for resale | R$ 207 |  |

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