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RELATED-PARTY TRANSACTIONS - Key Management compensation and other information from related parties (Details) R$ in Thousands | 12 Months Ended
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Dec. 31, 2020 BRL (R$) EquityInstruments | Dec. 31, 2019 BRL (R$) EquityInstruments | Dec. 31, 2018 EquityInstruments
Key Management |  |  |
RELATED PARTY TRANSACTIONS |  |  |
Salaries, variable compensation and benefits | R$ | R$ 41,165 | R$ 32,359 |
Contributions to defined contribution pension plans | R$ | 1,416 | 1,687 |
Cost of long-term incentive plan | R$ | 39,766 | 26,631 |
Fundacao Gerdau, Instituto Gerdau and Fundacao Ouro Branco |  |  |
RELATED PARTY TRANSACTIONS |  |  |
Contributions to defined contribution pension plans | R$ | R$ 104,322 | R$ 96,191 |
Restricted and Performance Shares | Key Management |  |  |
Restricted shares granted to Management |  |  |
Balance, beginning of year | 6,717,872 | 6,717,872 | 6,375,547
Granted | 733,218 | 1,083,116 |
Exercised | (937,325) | (627,076) |
Cancelled | (64,112) | (38,553) |
Others | (6,595) | 75,163 |
Balance, end of year | 6,456,248 | 6,717,872 | 6,717,872

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- Definition The amount of compensation to key management personnel. [Refer: Key management personnel of entity or parent [member]] + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Name IAS -Number 24 -IssueDate 2020-01-01 -Paragraph 17 -URI http://eifrs.ifrs.org/eifrs/xifrs-link?type=IAS&num=24&code=ifrs-tx-2020-en-r&anchor=para_17&doctype=Standard -URIDate 2020-01-01 + Details
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