Derivatives - Schedule of Financial Assets subject to Offsetting, Enforceable Master Netting Arrangements and Similar Agreements (Detail) - BRL (R$) R$ in Millions	Dec. 31, 2018	Dec. 31, 2017
Disclosure of offsetting of financial assets [line items]
Net amount of financial assets presented in the statement of financial position	R$ 23,466	R$ 22,843
Net amount of financial assets presented in the statement of financial position	27,519	26,746
Securities purchased under agreements to resell [Member]
Disclosure of offsetting of financial assets [line items]
Gross amount of recognized financial assets	280,126	244,699
Gross amount offset in the statement of financial position	0	0
Net amount of financial assets presented in the statement of financial position	280,126	244,699
Related amounts not offset in the statement of Financial position, financial instruments	(2,822)	(575)
Related amounts not offset in the statement of Financial position, cash collateral received	0	0
Net amount	277,304	244,124
Gross amount of recognized financial liabilities	330,237	312,634
Gross amount offset in the statement of financial position	0	0
Net amount of financial assets presented in the statement of financial position	330,237	312,634
Related amounts not offset in the statement of Financial position, financial instruments	(23,079)	(14,489)
Net amount	307,158	298,145
Derivatives [member]
Disclosure of offsetting of financial assets [line items]
Gross amount of recognized financial assets	23,466	22,843
Gross amount offset in the statement of financial position	0	0
Net amount of financial assets presented in the statement of financial position	23,466	22,843
Related amounts not offset in the statement of Financial position, financial instruments	(3,091)	(3,138)
Related amounts not offset in the statement of Financial position, cash collateral received	0	0
Net amount	20,375	19,705
Gross amount of recognized financial liabilities	27,519	26,746
Gross amount offset in the statement of financial position	0	0
Net amount of financial assets presented in the statement of financial position	27,519	26,746
Related amounts not offset in the statement of Financial position, financial instruments	(3,091)	(3,138)
Related amounts not offset in the statement of Financial position, cash collateral received	(333)	(452)
Net amount	R$ 24,095	R$ 23,156

The amount of cash collateral pledged that is subject to an enforceable master netting arrangement or similar agreement and that is not set off against financial liabilities. [Refer: Financial liabilities]

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- Definition

The amount of cash collateral received that is subject to an enforceable master netting arrangement or similar agreement and that is not set off against financial assets. [Refer: Financial assets]

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Line items represent concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes of the table.

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The amount of financial instruments subject to an enforceable master netting arrangement or similar agreement that are not set off against financial assets. [Refer: Financial assets]

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The amount of financial instruments subject to an enforceable master netting arrangement or similar agreement that are not set off against financial liabilities. [Refer: Financial liabilities]

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- Definition

The amount of financial assets set off against financial liabilities when an entity: (a) currently has a legally enforceable right to set off the recognised amounts; and (b) intends either to settle on a net basis, or to realise the asset and settle the liability simultaneously. [Refer: Financial assets; Financial liabilities]

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The gross amount of recognised financial assets that are subject either to offsetting or to an enforceable master netting arrangement or similar agreement. [Refer: Financial assets]

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- Definition

The amount of financial liabilities set off against financial assets when an entity: (a) currently has a legally enforceable right to set off the recognised amounts; and (b) intends either to settle on a net basis or to realise the asset and settle the liability simultaneously. [Refer: Financial assets; Financial liabilities]

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The gross amount of recognised financial liabilities that are subject either to offsetting or to an enforceable master netting arrangement or similar agreement. [Refer: Financial liabilities]

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The amount remaining after deducting the amounts subject to an enforceable master netting arrangement or similar agreement that were not set off against financial assets, from the net amount of financial assets subject to offsetting or subject to an enforceable master netting arrangement or similar agreement presented in the statement of financial position.

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The net amount of financial assets that are subject either to offsetting or to an enforceable master netting arrangement or similar agreement, presented in the statement of financial position. [Refer: Financial assets]

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The amount remaining after deducting the amounts subject to an enforceable master netting arrangement or similar agreement that were not set off against financial liabilities, from the net amount of financial liabilities subject to offsetting or subject to an enforceable master netting arrangement or similar agreement presented in the statement of financial position.

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The net amount of financial liabilities that are subject either to offsetting or to an enforceable master netting arrangement or similar agreement, presented in the statement of financial position. [Refer: Financial liabilities]

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