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Interest and similar income and expense and net gain (loss) on investment securities and derivatives - Summary of Interest and Similar Expense (Detail) - BRL (R$) R$ in Millions | 12 Months Ended
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Dec. 31, 2019 | Dec. 31, 2018 | Dec. 31, 2016
Disclosure Of Interest Expense [Line items] |  |  |
Interest and similar expense | R$ (75,958) | R$ (70,612) | R$ (78,330)
Bank Deposits [member] |  |  |
Disclosure Of Interest Expense [Line items] |  |  |
Interest and similar expense | (18,559) | (17,484) | (13,340)
Securities sold under repurchase agreements [member] |  |  |
Disclosure Of Interest Expense [Line items] |  |  |
Interest and similar expense | (20,473) | (20,889) | (33,087)
Inter bank market debt [member] |  |  |
Disclosure Of Interest Expense [Line items] |  |  |
Interest and similar expense | (13,231) | (13,587) | (10,059)
Institutional market debt [Member] |  |  |
Disclosure Of Interest Expense [Line items] |  |  |
Interest and similar expense | (6,837) | (6,773) | (6,852)
Finance Expense [member] |  |  |
Disclosure Of Interest Expense [Line items] |  |  |
Interest and similar expense | (16,720) | (11,815) | (14,918)
Other interest and similar expense [member] |  |  |
Disclosure Of Interest Expense [Line items] |  |  |
Interest and similar expense | R$ (138) | R$ (64) | R$ (74)

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