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RELATED-PARTY TRANSACTIONS - Intercompany loans (Details) - BRL (R$) R$ in Thousands | 12 Months Ended
--- | ---
Dec. 31, 2019 | Dec. 31, 2018 | Dec. 31, 2017
RELATED PARTY TRANSACTIONS |  |  |
Assets | R$ 95,445 | R$ 27,939 |
Liabilities |  | (1,350) |
Net financial income | 4,767 | 545 | R$ 95
Diaco S.A. |  |  |
RELATED PARTY TRANSACTIONS |  |  |
Liabilities |  | (1,350) |
Gerdau Corsa S.A.P.I de C.V. |  |  |
RELATED PARTY TRANSACTIONS |  |  |
Assets | 73,607 | 72 |
Fundacao Gerdau |  |  |
RELATED PARTY TRANSACTIONS |  |  |
Assets | R$ 21,838 | R$ 27,867 |

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