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Minimum cash and minimum capital - Additional Information (Detail) | 12 Months Ended
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Dec. 31, 2020
Minimum Capital [Abstract] |
Item Of Minimum Capital Requirement For Credit Risk | 8

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- Definition The amount of minimum capital requirement for credit risk, percent of the sum of credit-risk-weighted asset transactions without delivery against payment. + References No definition available. + Details
Name: | bbar_ItemOfMinimumCapitalRequirementForCreditRisk
Namespace Prefix: | bbar_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

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- Definition Minimum Capital + References No definition available. + Details
Name: | bbar_MinimumCapitalAbstract
Namespace Prefix: | bbar_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration