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Loan Operations and Lease Operations Portfolio - Summary of Reconciliation of Expected Loan Losses for Loan Operations and Lease Operations (Parenthetical) (Detail) - BRL (R$) R$ in Millions |  |  |  |  |  | 12 Months Ended
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Dec. 31, 2018 | Jan. 01, 2018 | Dec. 31, 2017 | Jan. 01, 2017 | Dec. 31, 2016 | Dec. 31, 2018 | Dec. 31, 2017
Disclosure of loans and lease operations [Abstract] |  |  |  |  |  |  |
Expected loan losses for financial guarantees pledged | R$ (1,191) | R$ (1,907) | R$ (1,907) | R$ (1,580) | R$ (1,580) |  |
Commitments released | R$ (2,601) | R$ (3,015) | R$ (3,015) | R$ (2,691) | R$ (2,691) | R$ (2,601) | R$ (3,015)

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