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TAX, CIVIL AND LABOR CLAIMS AND CONTINGENT ASSETS - Civil Contingencies and Administrative proceedings (Details) R$ in Thousands, $ in Millions |  |  |  | 12 Months Ended |  |
--- | --- | --- | --- | --- | --- | ---
Oct. 31, 2016 USD ($) | Aug. 01, 2013 BRL (R$) | Sep. 23, 2005 BRL (R$) item | Dec. 31, 2017 BRL (R$) item | Jul. 05, 2017 BRL (R$) | Jul. 14, 2015
Civil contingencies | Antitrust Legislation |  |  |  |  |  |
Contingencies |  |  |  |  |  |
Number of civil construction unions | item |  |  | 2 |  |  |
Fine for existence of cartel on gross revenues (in percentage) |  |  | 7.00% |  |  |
Fine for existence of cartel |  |  | R$ 245,070 |  |  |
Fine for existence of cartel updated by judicial accounting |  | R$ 417,820 |  |  |  |
Number of lawsuits that challenged the investigation | item |  |  |  | 2 |  |
Civil contingencies | Other Demands Of a Civil Nature |  |  |  |  |  |
Contingencies |  |  |  |  |  |
Estimated financial effect of contingent liabilities |  |  |  | R$ 191,112 |  |
Civil contingencies | Securities Class Action |  |  |  |  |  |
Contingencies |  |  |  |  |  |
Alleged amount of nonpayment of taxes | $ | $ 429 |  |  |  |  |
Settlement amount |  |  |  |  | R$ 15 |
Gerdau Acos Longos S.A. | Administrative proceedings contingencies |  |  |  |  |  |
Administrative proceedings disclosures |  |  |  |  |  |
Percentage of voting equity interests acquired |  |  |  |  |  | 4.77%
Gerdau Acominas S.A. | Administrative proceedings contingencies |  |  |  |  |  |
Administrative proceedings disclosures |  |  |  |  |  |
Percentage of voting equity interests acquired |  |  |  |  |  | 3.50%
Gerdau Acos Especiais S.A. | Administrative proceedings contingencies |  |  |  |  |  |
Administrative proceedings disclosures |  |  |  |  |  |
Percentage of voting equity interests acquired |  |  |  |  |  | 2.39%
Gerdau America Latina Participacoes S.A. | Administrative proceedings contingencies |  |  |  |  |  |
Administrative proceedings disclosures |  |  |  |  |  |
Percentage of voting equity interests acquired |  |  |  |  |  | 4.90%

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- Definition The fine levied on the company and other long steel producers as a percentage of gross revenues in the year before administrative proceedings was commenced. + References No definition available. + Details
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