CONSOLIDATED FINANCIAL STATEMENTS - Total cash paid for business combinations (Details) R$ in Thousands	12 Months Ended
Dec. 31, 2015 BRL (R$)
Business Combinations
Companies / interest acquired	R$ 20,929
Interest increase in subsidiaries	339,068
Armacero Industrial y Comercial S.A.
Business Combinations
Companies / interest acquired	20,929
Gerdau Acos Longos S.A., Gerdau Acominas S.A., Gerdau Acos Especiais S.A., Gerdau America Latina Participacoes S.A.
Business Combinations
Interest increase in subsidiaries	R$ 339,068

The aggregate cash flows used in obtaining control of subsidiaries or other businesses, classified as investing activities. [Refer: Subsidiaries [member]]

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Line items represent concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes of the table.

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The cash outflow for changes in ownership interests in subsidiaries that do not result in a loss of control. [Refer: Subsidiaries [member]]

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