Financial assets at fair value through other comprehensive income - Debt securities FVOCI (Detail) - ARS ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Debt securities held fvoci [Abstract]
BCRA Liquidity Bills	$ 29,076,683	$ 20,834,239
Government securities	16,031,680	15,099,605
Private securities - Corporate bonds	70,150	174,058
BCRA Liquidity Bills - Pledged as collateral	0	1,633,340
Government securities - Pledged as collateral	0	24,667
TOTAL	$ 45,178,513	$ 37,765,909

The amount of Central Bank of the Argentine Republic bills pledged as collateral held by the entity.

No definition available.

Name:	bbar_BcraBillsPledgedAsCollateralFvoci
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Period Type:	instant

The amount of Central Bank of the Argentine Republic liquidity bills pledged as collateral held by the entity.

No definition available.

Name:	bbar_BcraLiquidityBillsFvoci
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Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

The amount of instruments of debt securities held by the entity at fair value through other comprehensive income.

No definition available.

Name:	bbar_DebtSecuritiesHeldFvoci
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Data Type:	xbrli:monetaryItemType
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Debt securities held fvoci abstract

No definition available.

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The amount of government securities held by the entity.

No definition available.

Name:	bbar_GovernmentSecuritiesFvoci
Namespace Prefix:	bbar_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

The amount of Governments investment pledged as collateral securities by the entity.

No definition available.

Name:	bbar_GovernmentSecuritiesPledgedAsCollateralFvoci
Namespace Prefix:	bbar_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

The amount of debt investment securities by the entity that were issued by a corporate entity.

No definition available.

Name:	bbar_PrivateSecuritiesCorporateBondsFvoci
Namespace Prefix:	bbar_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant