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Taxes - Summary of Calculation of Tax Rates (Detail)	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Disclosure of effective income tax rate [Abstract]
Income tax	15.00%
Additional income tax	10.00%
Social contribution	20.00%	15.00%

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- Definition

Additional income tax rate.

+ References

No definition available.

+ Details

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X

- Definition

Disclosure of effective income tax rate.

+ References

No definition available.

+ Details

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- Definition

Income tax rate.

+ References

No definition available.

+ Details

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X

- Definition

Social contribution tax rate.

+ References

No definition available.

+ Details

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Namespace Prefix:	itub_
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