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v3.19.1

Insurance Contracts and Private Pension - Additional Information (Detail) | 12 Months Ended
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Dec. 31, 2018 Pension_Plan
Disclosure of Reinsurance Transactions [Line Items] |
Number of private pension products | 3
Top of range [member] |
Disclosure of Reinsurance Transactions [Line Items] |
Percentage of income tax deduction | 12.00%

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- Definition Disclosure of reinsurance transactions. + References No definition available. + Details
Name: | itub_DisclosureOfReinsuranceTransactionsLineItems
Namespace Prefix: | itub_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

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- Definition Number of pension plans. + References No definition available. + Details
Name: | itub_NumberOfPensionPlans
Namespace Prefix: | itub_
Data Type: | xbrli:integerItemType
Balance Type: | na
Period Type: | duration

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- Definition Percentage of income tax deduction. + References No definition available. + Details
Name: | itub_PercentageOfIncomeTaxDeduction
Namespace Prefix: | itub_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | instant

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- Details
Name: | ifrs-full_RangeAxis=ifrs-full_TopOfRangeMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |