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16. CONCESSION FINANCIAL AND SECTOR ASSETS AND LIABILITIES (Details 5) - BRL (R$) R$ in Millions | 12 Months Ended
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Dec. 31, 2019 | Dec. 31, 2018 | Dec. 31, 2017
Disclosure Of Financial Assets And Financial Liabilities With The Tariff Adjustments [abstract] |  |  |
Beginning balance | R$ 1,080 | R$ (46) | R$ (407)
Additions | 724 | 1,638 | 811
Amortization | (666) | 335 | 177
Others - R&D Reimbursement |  | (115) |
Payments from the Flag Tariff Centralizing Account | (361) | (794) | (586)
Updating - Selic rate (Note 31) | 105 | 62 | (41)
Ending balance | R$ 882 | R$ 1,080 | R$ (46)

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