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

X

- 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

X

- Definition

Minimum Capital

+ References

No definition available.

+ Details

Name:	bbar_MinimumCapitalAbstract
Namespace Prefix:	bbar_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration