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Risk and Capital Management - Summary of Implementation of Basel III Rules (Detail) | 12 Months Ended
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Dec. 31, 2019 | Dec. 31, 2018
Schedule for Implementation of Basel III Rules [Line Items] |  |
Common Equity Tier I | 4.50% | 4.50%
Tier I | 6.00% | 6.00%
Total Capital | 8.00% | 8.625%
Additional Capital Buffers (ACP) | 3.50% | 2.375%
Conservation | 2.50% | 1.875%
Countercyclical | 0.00% | 0.00%
Systemic | 1.00% | 0.50%
Common Equity Tier I + ACP | 8.00% | 6.875%
Total Capital + ACP | 11.50% | 11.00%
Prudential Adjustments Deductions | 100.00% | 100.00%

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- Definition Additional common equity tier one capital percentage of risk weighted assets. + References No definition available. + Details
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- Definition Capital and additional common equity tier one capital percentage of risk weighted assets. + References No definition available. + Details
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Data Type: | num:percentItemType
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- Definition Capital risk weighted assets percentage. + References No definition available. + Details
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Namespace Prefix: | itub_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | duration

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- Definition Common equity and additional common equity tier one capital percentage of risk weighted assets. + References No definition available. + Details
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Data Type: | num:percentItemType
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- Definition Common equity tier one capital percentage of risk weighted assets. + References No definition available. + Details
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- Definition Conservation percentage of risk weighted assets. + References No definition available. + Details
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- Definition Counter cyclical percentage of risk weighted assets. + References No definition available. + Details
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Period Type: | duration

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- Definition Prudential adjustments deductions percentage of risk weighted assets. + References No definition available. + Details
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Data Type: | num:percentItemType
Balance Type: | na
Period Type: | duration

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- Definition Schedule for Implementation of Basel III Rules [Line Items] + References No definition available. + Details
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- Definition Systemic percentage of risk weighted assets. + References No definition available. + Details
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Namespace Prefix: | itub_
Data Type: | num:percentItemType
Balance Type: | na
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- Definition Tier one capital percentage of risk weighted assets. + References No definition available. + Details
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