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Risk and Capital Management - Summary of Funds Obtained Through the Issuance of Subordinated Debt Securities (Parenthetical) (Detail) | Dec. 31, 2018
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Brazil, Brazil Real | Subordinated financial bills eight [Member] |
Disclosure of assets and liabilities according to their remaining contractual maturities [Line Items] |
Borrowings interest rate basis adjustment | 111.00%
Brazil, Brazil Real | Subordinated financial bills nine [Member] | Bottom of range [member] |
Disclosure of assets and liabilities according to their remaining contractual maturities [Line Items] |
Borrowings interest rate basis adjustment | 109.25%
Brazil, Brazil Real | Subordinated financial bills nine [Member] | Top of range [member] |
Disclosure of assets and liabilities according to their remaining contractual maturities [Line Items] |
Borrowings interest rate basis adjustment | 110.50%
Brazil, Brazil Real | Subordinated financial bills ten [Member] |
Disclosure of assets and liabilities according to their remaining contractual maturities [Line Items] |
Borrowings interest rate basis adjustment | 11.96%
Brazil, Brazil Real | Subordinated financial bills eleven [Member] | Bottom of range [member] |
Disclosure of assets and liabilities according to their remaining contractual maturities [Line Items] |
Borrowings interest rate basis adjustment | 4.70%
Brazil, Brazil Real | Subordinated financial bills eleven [Member] | Top of range [member] |
Disclosure of assets and liabilities according to their remaining contractual maturities [Line Items] |
Borrowings interest rate basis adjustment | 6.30%
Brazil, Brazil Real | Subordinated financial bills thirteen [Member] | Bottom of range [member] |
Disclosure of assets and liabilities according to their remaining contractual maturities [Line Items] |
Borrowings interest rate basis adjustment | 6.00%
Brazil, Brazil Real | Subordinated financial bills thirteen [Member] | Top of range [member] |
Disclosure of assets and liabilities according to their remaining contractual maturities [Line Items] |
Borrowings interest rate basis adjustment | 6.17%
Brazil, Brazil Real | Subordinated financial bills fifteen [Member] | Bottom of range [member] |
Disclosure of assets and liabilities according to their remaining contractual maturities [Line Items] |
Borrowings interest rate basis adjustment | 5.15%
Brazil, Brazil Real | Subordinated financial bills fifteen [Member] | Top of range [member] |
Disclosure of assets and liabilities according to their remaining contractual maturities [Line Items] |
Borrowings interest rate basis adjustment | 5.83%
Brazil, Brazil Real | Subordinated financial bills sixteen [Member] |
Disclosure of assets and liabilities according to their remaining contractual maturities [Line Items] |
Borrowings interest rate basis adjustment | 4.63%
Brazil, Brazil Real | Subordinated financial bills six [Member] | Bottom of range [member] |
Disclosure of assets and liabilities according to their remaining contractual maturities [Line Items] |
Borrowings interest rate basis adjustment | 109.00%
Brazil, Brazil Real | Subordinated financial bills six [Member] | Top of range [member] |
Disclosure of assets and liabilities according to their remaining contractual maturities [Line Items] |
Borrowings interest rate basis adjustment | 109.70%
Brazil, Brazil Real | Subordinated financial bills seven [Member] |
Disclosure of assets and liabilities according to their remaining contractual maturities [Line Items] |
Borrowings interest rate basis adjustment | 110.00%
United States of America, Dollars | Subordinated euronotes [Member] |
Disclosure of assets and liabilities according to their remaining contractual maturities [Line Items] |
Borrowings interest rate | 6.20%
United States of America, Dollars | Subordinated euronotes one [Member] |
Disclosure of assets and liabilities according to their remaining contractual maturities [Line Items] |
Borrowings interest rate | 5.75%
United States of America, Dollars | Subordinated euronotes two [Member] | Bottom of range [member] |
Disclosure of assets and liabilities according to their remaining contractual maturities [Line Items] |
Borrowings interest rate | 5.75%
United States of America, Dollars | Subordinated euronotes two [Member] | Top of range [member] |
Disclosure of assets and liabilities according to their remaining contractual maturities [Line Items] |
Borrowings interest rate | 6.20%
United States of America, Dollars | Subordinated euronotes three [Member] |
Disclosure of assets and liabilities according to their remaining contractual maturities [Line Items] |
Borrowings interest rate | 6.20%
United States of America, Dollars | Subordinated euronotes four [Member] | Bottom of range [member] |
Disclosure of assets and liabilities according to their remaining contractual maturities [Line Items] |
Borrowings interest rate | 5.50%
United States of America, Dollars | Subordinated euronotes four [Member] | Top of range [member] |
Disclosure of assets and liabilities according to their remaining contractual maturities [Line Items] |
Borrowings interest rate | 5.65%
United States of America, Dollars | Subordinated euronotes five [Member] |
Disclosure of assets and liabilities according to their remaining contractual maturities [Line Items] |
Borrowings interest rate | 5.13%

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