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Risk and Capital Management - Summary of Exposure Weighted by Credit Risk (Detail) - BRL (R$) R$ in Millions | Dec. 31, 2018 | Dec. 31, 2017
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Disclosure of credit risk exposure [line items] |  |
Exposure Weighted by Credit Risk (RWACPAD) | R$ 714,969 | R$ 660,516
Marketable securities [member] |  |
Disclosure of credit risk exposure [line items] |  |
Exposure Weighted by Credit Risk (RWACPAD) | 40,276 | 45,629
Loan Operations - Retail [Member] |  |
Disclosure of credit risk exposure [line items] |  |
Exposure Weighted by Credit Risk (RWACPAD) | 124,356 | 114,141
Loan Operations - Non-Retail [Member] |  |
Disclosure of credit risk exposure [line items] |  |
Exposure Weighted by Credit Risk (RWACPAD) | 256,958 | 240,816
Joint Liabilities - Retail [Member] |  |
Disclosure of credit risk exposure [line items] |  |
Exposure Weighted by Credit Risk (RWACPAD) | 140 | 172
Joint Liabilities - Non-Retail [Member] |  |
Disclosure of credit risk exposure [line items] |  |
Exposure Weighted by Credit Risk (RWACPAD) | 43,288 | 45,405
Loan Commitments - Retail [Member] |  |
Disclosure of credit risk exposure [line items] |  |
Exposure Weighted by Credit Risk (RWACPAD) | 33,871 | 31,058
Loan Commitments - Non-Retail [Member] |  |
Disclosure of credit risk exposure [line items] |  |
Exposure Weighted by Credit Risk (RWACPAD) | 10,673 | 9,017
Derivatives - Future potential gain [member] |  |
Disclosure of credit risk exposure [line items] |  |
Exposure Weighted by Credit Risk (RWACPAD) | 4,193 | 5,457
Agency transition [member] |  |
Disclosure of credit risk exposure [line items] |  |
Exposure Weighted by Credit Risk (RWACPAD) | 3,330 |
Other exposures [Member] |  |
Disclosure of credit risk exposure [line items] |  |
Exposure Weighted by Credit Risk (RWACPAD) | R$ 197,884 | R$ 168,821

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- Definition The amount that best represents the maximum exposure to credit risk without taking into account any collateral held or other credit enhancements (for example, netting agreements that do not qualify for offset in accordance with IAS 32). [Refer: Credit risk [member]] + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Note Effective 2018-01-01 -Name IFRS -Number 7 -IssueDate 2017-01-01 -Paragraph 35K -Subparagraph a -URI http://eifrs.ifrs.org/eifrs/XBRL?type=IFRS&num=7&date=2017-03-01&anchor=para_35K_a&doctype=Standard -URIDate 2017-03-09 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Note Expiry date 2018-01-01 -Name IFRS -Number 7 -IssueDate 2017-01-01 -Paragraph 36 -Subparagraph a -URI http://eifrs.ifrs.org/eifrs/XBRL?type=IFRS&num=7&date=2017-03-02&anchor=para_36_a&doctype=Standard&book=B -URIDate 2017-03-09 + Details
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