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Interest and similar income and expense and net gain (loss) on investment securities and derivatives - Schedule of Adjustments to Fair Value of Financial Assets and Liabilities (Detail) - BRL (R$) R$ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Disclosure of financial assets and liabilities measured at fair value [Line Items]
Adjustments to Fair Value of Financial Assets and Liabilities	R$ (4,834)	R$ 4,181	R$ 7,066
Derivatives [member]
Disclosure of financial assets and liabilities measured at fair value [Line Items]
Adjustments to Fair Value of Financial Assets and Liabilities	(260)	2,028	7,332
Financial Assets Designated At Fair Value Through Profit Or Loss Equity Securities [Member]
Disclosure of financial assets and liabilities measured at fair value [Line Items]
Adjustments to Fair Value of Financial Assets and Liabilities	(218)	180	48
Financial assets designated at fair value through profit or loss [member]
Disclosure of financial assets and liabilities measured at fair value [Line Items]
Adjustments to Fair Value of Financial Assets and Liabilities	(4,110)	2,138	684
Financial assets at fair value through other comprehensive income [Member]
Disclosure of financial assets and liabilities measured at fair value [Line Items]
Adjustments to Fair Value of Financial Assets and Liabilities	(254)	(128)	(851)
Financial liabilities at fair value through profit or loss, category [member]
Disclosure of financial assets and liabilities measured at fair value [Line Items]
Adjustments to Fair Value of Financial Assets and Liabilities	R$ 8	R$ (37)	R$ (147)

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- Definition

Adjustments for gains (losses) on changes in the fair value of derivatives to reconcile profit (loss) to net cash flow from (used in) operating activities. [Refer: At fair value [member]; Derivatives [member]; Profit (loss)]

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Name IAS
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-IssueDate 2017-01-01
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- Definition

Line items represent financial assets and liabilities measured at fair value.

+ References

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