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Period Type:	instant

The amount of cash collateral and settlement balance assets, expressed as a percentage.

No definition available.

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The amount of cash and bank balances held at central banks, expressed as a percentage.

No definition available.

Name:	bbplc_CashAndBankBalancesAtCentralBanksPercentage
Namespace Prefix:	bbplc_
Data Type:	dtr-types1:percentItemType
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Debt Instruments Held At Amortised Cost, Percentage

No definition available.

Name:	bbplc_DebtInstrumentsHeldAtAmortisedCostPercentage
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Data Type:	dtr-types1:percentItemType
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The amount of financial assets classified as derivative instruments, expressed as a percentage.

No definition available.

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The amount of financial assets at fair value through profit or loss classified as held for trading, expressed as a percentage. A financial asset is classified as held for trading if: (a) it is acquired principally for the purpose of selling it in the near term; (b) on initial recognition it is part of a portfolio of identified financial instruments that are managed together and for which there is evidence of a recent actual pattern of short-term profit-taking; or (c) it is a derivative (except for a derivative that is a financial guarantee contract or a designated and effective hedging instrument). [Refer: At fair value [member]; Financial assets at fair value through profit or loss]

No definition available.

Name:	bbplc_FinancialAssetsAtFairValueThroughProfitOrLossClassifiedAsHeldForTradingPercentage
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The amount of financial assets (expressed as a percentage) that are measured at fair value and for which gains (losses) are recognised in profit or loss. A financial asset shall be measured at fair value through profit or loss unless it is measured at amortised cost or at fair value through other comprehensive income. A gain (loss) on a financial asset measured at fair value shall be recognised in profit or loss unless it is part of a hedging relationship, it is an investment in an equity instrument for which the entity has elected to present gains and losses in other comprehensive income or it is a financial asset measured at fair value through other comprehensive income. [Refer: At fair value [member]; Financial assets]

No definition available.

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The amount (expressed as a percentage) of financial assets that are measured at fair value through other comprehensive income. A financial asset shall be measured at fair value through other comprehensive income if both of the following conditions are met: (a) the financial asset is held within a business model whose objective is achieved by both collecting contractual cash flows and selling financial assets and (b) the contractual terms of the financial asset give rise on specified dates to cash flows that are solely payments of principal and interest on the principal amount outstanding. [Refer: At fair value [member]; Financial assets]

No definition available.

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The amount loans and advances at amortised cost, expressed as a percentage.

No definition available.

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Non-Current Assets or Disposal Groups Classified as Held For Sale, Percentage

No definition available.

Name:	bbplc_NonCurrentAssetsOrDisposalGroupsClassifiedAsHeldForSalePercentage
Namespace Prefix:	bbplc_
Data Type:	dtr-types1:percentItemType
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- References

No definition available.

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- References

No definition available.

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The amount of financial assets that the entity does not separately disclose in the same statement or note, expressed as a percentage.

No definition available.

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The amount of instruments purchased for resale in reverse repurchase agreements and cash collateral on securities borrowed, expressed as a percentage.

No definition available.

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The amount of a present economic resource controlled by the entity as a result of past events. Economic resource is a right that has the potential to produce economic benefits.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Name IFRS
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Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Name IFRS
-Number 8
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-Paragraph 28
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-URI https://taxonomy.ifrs.org/xifrs-link?type=IFRS&num=8&code=ifrs-tx-2025-en-r&anchor=para_28_c&doctype=Standard
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-URIDate 2025-03-27

Reference 4: http://www.xbrl.org/2003/role/disclosureRef
-Name IFRS
-Number 8
-IssueDate 2025-01-01
-Paragraph 23
-URI https://taxonomy.ifrs.org/xifrs-link?type=IFRS&num=8&code=ifrs-tx-2025-en-r&anchor=para_23&doctype=Standard
-URIDate 2025-03-27

Reference 5: http://www.xbrl.org/2003/role/disclosureRef
-Name IFRS
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-Paragraph 93
-Subparagraph b
-URI https://taxonomy.ifrs.org/xifrs-link?type=IFRS&num=13&code=ifrs-tx-2025-en-r&anchor=para_93_b&doctype=Standard
-URIDate 2025-03-27

Reference 6: http://www.xbrl.org/2003/role/disclosureRef
-Note Effective 2027-01-01
-Name IFRS
-Number 19
-IssueDate 2025-01-01
-Paragraph 95
-Subparagraph b
-URI https://taxonomy.ifrs.org/xifrs-link?type=IFRS&num=19&code=ifrs-tx-2025-en-r&anchor=para_95_b&doctype=Standard
-URIDate 2025-03-27

Reference 7: http://www.xbrl.org/2003/role/disclosureRef
-Note Effective 2027-01-01
-Name IFRS
-Number 19
-IssueDate 2025-01-01
-Paragraph 95
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-URI https://taxonomy.ifrs.org/xifrs-link?type=IFRS&num=19&code=ifrs-tx-2025-en-r&anchor=para_95_b&doctype=Standard
-URIDate 2025-03-27

Reference 8: http://www.xbrl.org/2003/role/disclosureRef
-Note Effective 2027-01-01
-Name IFRS
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-URIDate 2025-03-27

Reference 9: http://www.xbrl.org/2003/role/disclosureRef
-Note Effective 2027-01-01
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-URIDate 2025-03-27

Reference 10: http://www.xbrl.org/2003/role/disclosureRef
-Note Expiry date 2027-01-01
-Name IAS
-Number 1
-IssueDate 2025-01-01
-Paragraph 55
-URI https://taxonomy.ifrs.org/xifrs-link?type=IAS&num=1&code=ifrs-tx-2025-en-b&anchor=para_55&doctype=Standard
-URIDate 2025-03-27

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The amount of bank acceptances recognised as assets.

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Note Expiry date 2027-01-01
-Name IAS
-Number 1
-IssueDate 2025-01-01
-Paragraph 55
-URI https://taxonomy.ifrs.org/xifrs-link?type=IAS&num=1&code=ifrs-tx-2025-en-b&anchor=para_55&doctype=Standard
-URIDate 2025-03-27

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The amount of cash and bank balances held at central banks.

Name:	ifrs-full_CashAndBankBalancesAtCentralBanks
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The amount of instruments representing indebtedness held by the entity at amortised cost. [Refer: Debt instruments held; Financial assets at amortised cost]

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Namespace Prefix:	ifrs-full_
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The amount of financial assets classified as derivative instruments. [Refer: Financial assets; Derivatives [member]]

Name:	ifrs-full_DerivativeFinancialAssets
Namespace Prefix:	ifrs-full_
Data Type:	xbrli:monetaryItemType
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Period Type:	instant

The amount of financial assets that are measured at fair value and for which gains (losses) are recognised in profit or loss. A financial asset shall be measured at fair value through profit or loss unless it is measured at amortised cost or at fair value through other comprehensive income. A gain (loss) on a financial asset measured at fair value shall be recognised in profit or loss unless it is part of a hedging relationship, it is an investment in an equity instrument for which the entity has elected to present gains and losses in other comprehensive income or it is a financial asset measured at fair value through other comprehensive income. [Refer: At fair value [member]; Financial assets]

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Name IFRS
-Number 7
-IssueDate 2025-01-01
-Paragraph 8
-Subparagraph a
-URI https://taxonomy.ifrs.org/xifrs-link?type=IFRS&num=7&code=ifrs-tx-2025-en-r&anchor=para_8_a&doctype=Standard
-URIDate 2025-03-27

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Note Effective 2027-01-01
-Name IFRS
-Number 19
-IssueDate 2025-01-01
-Paragraph 44
-Subparagraph a
-URI https://taxonomy.ifrs.org/xifrs-link?type=IFRS&num=19&code=ifrs-tx-2025-en-r&anchor=para_44_a&doctype=Standard
-URIDate 2025-03-27

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Note Effective 2027-01-01
-Name IFRS
-Number 19
-IssueDate 2025-01-01
-Paragraph 44
-Subparagraph a
-URI https://taxonomy.ifrs.org/xifrs-link?type=IFRS&num=19&code=ifrs-tx-2025-en-r&anchor=para_44_a&doctype=Standard
-URIDate 2025-03-27

Name:	ifrs-full_FinancialAssetsAtFairValueThroughProfitOrLoss
Namespace Prefix:	ifrs-full_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

The amount of financial assets at fair value through profit or loss classified as held for trading. A financial asset is classified as held for trading if: (a) it is acquired principally for the purpose of selling it in the near term; (b) on initial recognition it is part of a portfolio of identified financial instruments that are managed together and for which there is evidence of a recent actual pattern of short-term profit-taking; or (c) it is a derivative (except for a derivative that is a financial guarantee contract or a designated and effective hedging instrument). [Refer: At fair value [member]; Financial assets at fair value through profit or loss, mandatorily measured at fair value]

Name:	ifrs-full_FinancialAssetsAtFairValueThroughProfitOrLossClassifiedAsHeldForTrading
Namespace Prefix:	ifrs-full_
Data Type:	xbrli:monetaryItemType
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The amount of financial assets that are measured at fair value through other comprehensive income. A financial asset shall be measured at fair value through other comprehensive income if both of the following conditions are met: (a) the financial asset is held within a business model whose objective is achieved by both collecting contractual cash flows and selling financial assets and (b) the contractual terms of the financial asset give rise on specified dates to cash flows that are solely payments of principal and interest on the principal amount outstanding. [Refer: At fair value [member]; Financial assets]

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Name IFRS
-Number 7
-IssueDate 2025-01-01
-Paragraph 8
-Subparagraph h
-URI https://taxonomy.ifrs.org/xifrs-link?type=IFRS&num=7&code=ifrs-tx-2025-en-r&anchor=para_8_h&doctype=Standard
-URIDate 2025-03-27

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Note Effective 2027-01-01
-Name IFRS
-Number 19
-IssueDate 2025-01-01
-Paragraph 44
-Subparagraph e
-Clause i
-URI https://taxonomy.ifrs.org/xifrs-link?type=IFRS&num=19&code=ifrs-tx-2025-en-r&anchor=para_44_e_i&doctype=Standard
-URIDate 2025-03-27

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Note Effective 2027-01-01
-Name IFRS
-Number 19
-IssueDate 2025-01-01
-Paragraph 44
-Subparagraph e
-Clause i
-URI https://taxonomy.ifrs.org/xifrs-link?type=IFRS&num=19&code=ifrs-tx-2025-en-r&anchor=para_44_e_i&doctype=Standard
-URIDate 2025-03-27

Name:	ifrs-full_FinancialAssetsMeasuredAtFairValueThroughOtherComprehensiveIncome
Namespace Prefix:	ifrs-full_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

The amount of loans and advances the entity has made at amortised cost. [Refer: Loans and advances; Financial assets at amortised cost]

Name:	ifrs-full_LoansAndAdvancesAtAmortisedCost
Namespace Prefix:	ifrs-full_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

The amount of non-current assets or disposal groups classified as held for sale. [Refer: Disposal groups classified as held for sale [member]]

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Name IFRS
-Number 5
-IssueDate 2025-01-01
-Paragraph 38
-URI https://taxonomy.ifrs.org/xifrs-link?type=IFRS&num=5&code=ifrs-tx-2025-en-r&anchor=para_38&doctype=Standard
-URIDate 2025-03-27

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Data Type:	xbrli:monetaryItemType
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Period Type:	instant

The amount of financial assets that the entity does not separately disclose in the same statement or note. [Refer: Financial assets]

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Note Expiry date 2027-01-01
-Name IAS
-Number 1
-IssueDate 2025-01-01
-Paragraph 54
-Subparagraph d
-URI https://taxonomy.ifrs.org/xifrs-link?type=IAS&num=1&code=ifrs-tx-2025-en-b&anchor=para_54_d&doctype=Standard
-URIDate 2025-03-27

Name:	ifrs-full_OtherFinancialAssets
Namespace Prefix:	ifrs-full_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

The amount of instruments purchased for resale in reverse repurchase agreements and cash collateral on securities borrowed. [Refer: Repurchase agreements and cash collateral on securities lent]

Name:	ifrs-full_ReverseRepurchaseAgreementsAndCashCollateralOnSecuritiesBorrowed
Namespace Prefix:	ifrs-full_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

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Namespace Prefix:
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Namespace Prefix:
Data Type:	na
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Name:	ifrs-full_InternalCreditGradesAxis=ifrs-full_InternalCreditGradesMember
Namespace Prefix:
Data Type:	na
Balance Type:
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Name:	ifrs-full_ClassesOfFinancialAssetsAxis=bbplc_ReverseRepurchaseAgreementsMember
Namespace Prefix:
Data Type:	na
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Namespace Prefix:
Data Type:	na
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Namespace Prefix:
Data Type:	na
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Name:	ifrs-full_CategoriesOfFinancialAssetsAxis=ifrs-full_MortgagesMember
Namespace Prefix:
Data Type:	na
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Namespace Prefix:
Data Type:	na
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Namespace Prefix:
Data Type:	na
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Namespace Prefix:
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