Maturity Period

No definition available.

Name:	bbplc_MaturityPeriod
Namespace Prefix:	bbplc_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

The interest rate on borrowings. [Refer: Borrowings]

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Name IFRS
-Number 7
-IssueDate 2025-01-01
-Paragraph 7
-URI https://taxonomy.ifrs.org/xifrs-link?type=IFRS&num=7&code=ifrs-tx-2025-en-r&anchor=para_7&doctype=Standard
-URIDate 2025-03-27

+ Details

Name:	ifrs-full_BorrowingsInterestRate
Namespace Prefix:	ifrs-full_
Data Type:	dtr-2022:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

The amount of subordinated liabilities that have a specified repayment date. [Refer: Subordinated liabilities]

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Note Expiry date 2027-01-01
-Name IAS
-Number 1
-IssueDate 2025-01-01
-Paragraph 112
-Subparagraph c
-URI https://taxonomy.ifrs.org/xifrs-link?type=IAS&num=1&code=ifrs-tx-2025-en-b&anchor=para_112_c&doctype=Standard
-URIDate 2025-03-27

+ Details

Name:	ifrs-full_DatedSubordinatedLiabilities
Namespace Prefix:	ifrs-full_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Line items represent concepts included in a table. These concepts are used to disclose reportable information associated with members defined in one or many axes of the table.

+ References

No definition available.

+ Details

Name:	ifrs-full_DisclosureOfDetailedInformationAboutBorrowingsLineItems
Namespace Prefix:	ifrs-full_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

The nominal or face amount of a financial instrument, used to calculate payments made on that instrument.

+ References

+ Details

Name:	ifrs-full_NotionalAmount
Namespace Prefix:	ifrs-full_
Data Type:	xbrli:monetaryItemType
Balance Type:	na
Period Type:	instant

- Definition

The cash inflow from the issuing of subordinated liabilities. [Refer: Subordinated liabilities]

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Name IAS
-Number 7
-IssueDate 2025-01-01
-Paragraph 17
-URI https://taxonomy.ifrs.org/xifrs-link?type=IAS&num=7&code=ifrs-tx-2025-en-r&anchor=para_17&doctype=Standard
-URIDate 2025-03-27

+ Details

Name:	ifrs-full_ProceedsFromIssueOfSubordinatedLiabilities
Namespace Prefix:	ifrs-full_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

The cash outflow for repayments of subordinated liabilities. [Refer: Subordinated liabilities]

+ References

+ Details

Name:	ifrs-full_RepaymentsOfSubordinatedLiabilities
Namespace Prefix:	ifrs-full_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

Subordinated liabilities - Narrative (Details) € in Millions, ¥ in Millions, ¥ in Millions, £ in Millions, kr in Millions, SFr in Millions, $ in Millions, $ in Millions, $ in Millions	12 Months Ended
	Dec. 31, 2025 GBP (£)	Dec. 31, 2024 GBP (£)	Dec. 31, 2023 GBP (£)	Dec. 31, 2025 JPY (¥)	Dec. 31, 2025 EUR (€)	Dec. 31, 2025 USD ($)	Dec. 31, 2025 AUD ($)	Dec. 31, 2025 NOK (kr)	Dec. 31, 2025 CAD ($)	Dec. 31, 2025 CNY (¥)	Dec. 31, 2025 CHF (SFr)
Disclosure of detailed information about borrowings [line items]
Issuance of subordinated liabilities	£ 9,808	£ 11,222	£ 5,986
Redemption of subordinated debt	5,665	5,067	£ 7,431
Dated subordinated liabilities	45,699	42,278
Notional contract amount	100,079,291	83,792,768
Other subsidiaries
Disclosure of detailed information about borrowings [line items]
Dated subordinated liabilities	492	623
Barclays Bank PLC
Disclosure of detailed information about borrowings [line items]
Dated subordinated liabilities	45,699	42,278
Barclays Bank PLC loans issued intra-group to Barclays PLC \| Barclays PLC
Disclosure of detailed information about borrowings [line items]
Issuance of subordinated liabilities	9,139
Redemption of subordinated debt	5,438
4.616% Fixed Rate Resetting Subordinated Callable Notes (EUR 800m) \| Barclays PLC \| Fixed interest rate
Disclosure of detailed information about borrowings [line items]
Issuance of subordinated liabilities	£ 669
Interest rate	4.616%			4.616%	4.616%	4.616%	4.616%	4.616%	4.616%	4.616%	4.616%
3.750% Fixed Rate Resetting Subordinated Callable Notes \| Barclays PLC \| Fixed interest rate
Disclosure of detailed information about borrowings [line items]
Interest rate	3.75%			3.75%	3.75%	3.75%	3.75%	3.75%	3.75%	3.75%	3.75%
Redemption of subordinated debt	£ 115
USD Floating Rate Notes \| Other subsidiaries \| Floating interest rate
Disclosure of detailed information about borrowings [line items]
Redemption of subordinated debt	£ 112
6.125% Undated Subordinated Notes \| Barclays Bank PLC
Disclosure of detailed information about borrowings [line items]
Interest rate	6.125%			6.125%	6.125%	6.125%	6.125%	6.125%	6.125%	6.125%	6.125%
Maturity period	5 years
Various subordinated loans
Disclosure of detailed information about borrowings [line items]
Dated subordinated liabilities	£ 32,847	29,754
Various subordinated loans \| USD \| Dated subordinated liabilities
Disclosure of detailed information about borrowings [line items]
Notional contract amount \| $						$ 29,323
Various subordinated loans \| EUR \| Dated subordinated liabilities
Disclosure of detailed information about borrowings [line items]
Notional contract amount \| €					€ 9,180
Various subordinated loans \| GBP \| Dated subordinated liabilities
Disclosure of detailed information about borrowings [line items]
Notional contract amount	1,206
Various subordinated loans \| JPY \| Dated subordinated liabilities
Disclosure of detailed information about borrowings [line items]
Notional contract amount \| ¥				¥ 159,700
Various subordinated loans \| AUD \| Dated subordinated liabilities
Disclosure of detailed information about borrowings [line items]
Notional contract amount \| $							$ 2,390
Various subordinated loans \| NOK \| Dated subordinated liabilities
Disclosure of detailed information about borrowings [line items]
Notional contract amount \| kr								kr 220
Various subordinated loans \| CAD \| Dated subordinated liabilities
Disclosure of detailed information about borrowings [line items]
Notional contract amount									$ 450	¥ 700
Various subordinated loans \| CHF \| Dated subordinated liabilities
Disclosure of detailed information about borrowings [line items]
Notional contract amount \| SFr											SFr 260
Various subordinated loans \| Fixed interest rate
Disclosure of detailed information about borrowings [line items]
Dated subordinated liabilities	2,557	3,457
Various subordinated loans \| Floating interest rate
Disclosure of detailed information about borrowings [line items]
Dated subordinated liabilities	£ 0	£ 334