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Equity and Remuneration to Shareholders - Summary of Reserve for Obligatory Dividends Not Distributed (Detail) - BRL (R$) R$ in Millions | Dec. 31, 2017 | Dec. 31, 2016 | Dec. 31, 2015
--- | --- | --- | ---
Disclosure of reserves within equity [line items] |  |  |
Dividends withheld, arising from the net income | R$ 1,420 | R$ 1,420 | R$ 797
Dividends withheld, arising from the profit for 2015 [member] |  |  |
Disclosure of reserves within equity [line items] |  |  |
Dividends withheld, arising from the net income | 623 |  |
Dividends withheld, arising from the profit for 2014 [member] |  |  |
Disclosure of reserves within equity [line items] |  |  |
Dividends withheld, arising from the net income | R$ 797 |  |

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- Definition 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. + References No definition available. + Details
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- Definition Reserve for mandatory dividends not distributed. + References No definition available. + Details
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- Details
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- Details
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