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Fair Value of Financial Instruments - Summary of Carrying and Estimated Fair Values for Financial Instruments (Parenthetical) (Detail) - BRL (R$) R$ in Millions | Dec. 31, 2018 | Dec. 31, 2017 | Jan. 01, 2017
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Disclosure of fair value measurement of assets and liabilities [Line Items] |  |  |
Loan operations and lease operations | R$ 536,091 | R$ 497,719 | R$ 494,851
Financial assets designated at fair value through profit or loss [member] |  |  |
Disclosure of fair value measurement of assets and liabilities [Line Items] |  |  |
Loan operations and lease operations |  | R$ 102 |

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