Borrowings, Conversion Ratio Threshold, Percent

No definition available.

Name:	bbplc_BorrowingsConversionRatioThresholdPercent
Namespace Prefix:	bbplc_
Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	instant

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

+ 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_NotionalAmount
Namespace Prefix:	ifrs-full_
Data Type:	xbrli:monetaryItemType
Balance Type:	na
Period Type:	instant

- Definition

The amount of equity interest of an entity without share capital that the entity does not separately disclose in the same statement or note.

+ References

Reference 1: http://www.xbrl.org/2003/role/exampleRef
-Note Effective 2027-01-01
-Name IFRS
-Number 19
-IssueDate 2025-01-01
-Paragraph B9
-Subparagraph f
-URI https://taxonomy.ifrs.org/xifrs-link?type=IFRS&num=19&code=ifrs-tx-2025-en-r&anchor=para_B9_f&doctype=Appendix&subtype=B
-URIDate 2025-03-27

Reference 2: http://www.xbrl.org/2003/role/exampleRef
-Note Expiry date 2027-01-01
-Name IAS
-Number 1
-IssueDate 2025-01-01
-Paragraph 78
-Subparagraph e
-URI https://taxonomy.ifrs.org/xifrs-link?type=IAS&num=1&code=ifrs-tx-2025-en-b&anchor=para_78_e&doctype=Standard
-URIDate 2025-03-27

+ Details

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

Ordinary shares, preference shares and other equity - Disclosure of AT1 equity instruments (Details) € in Millions, £ in Millions, $ in Millions, $ in Millions	Dec. 31, 2025 GBP (£)	Dec. 31, 2025 EUR (€)	Dec. 31, 2025 SGD ($)	Dec. 31, 2025 USD ($)	Dec. 31, 2024 GBP (£)
Notional contract amount	£ 100,079,291				£ 83,792,768
Total AT1 equity instruments	10,446				9,604
Barclays Bank PLC
Total AT1 equity instruments	15,153				14,311
AT1 equity instruments \| Fixed interest rate \| Barclays Bank PLC
Total AT1 equity instruments	£ 10,446				9,604
Conversion ratio threshold, percent	7.00%	7.00%	7.00%	7.00%
AT1 equity instruments \| 7.125% Perpetual Subordinated Contingent Convertible Securities \| Fixed interest rate \| Barclays Bank PLC
Interest rate	7.125%	7.125%	7.125%	7.125%
Total AT1 equity instruments	£ 0				299
AT1 equity instruments \| 6.375% Perpetual Subordinated Contingent Convertible Securities \| Fixed interest rate \| Barclays Bank PLC
Interest rate	6.375%	6.375%	6.375%	6.375%
Total AT1 equity instruments	£ 0				495
AT1 equity instruments \| 6.125% Perpetual Subordinated Contingent Convertible Securities (USD1,500m) \| Fixed interest rate \| Barclays Bank PLC
Interest rate	6.125%	6.125%	6.125%	6.125%
Notional contract amount \| $				$ 1,500
Total AT1 equity instruments	£ 0				1,134
AT1 equity instruments \| 8.875% Perpetual Subordinated Contingent Convertible Securities \| Fixed interest rate \| Barclays Bank PLC
Interest rate	8.875%	8.875%	8.875%	8.875%
Total AT1 equity instruments	£ 1,237				1,237
AT1 equity instruments \| 8.300% Perpetual Subordinated Contingent Convertible Securities (SGD450m) \| Fixed interest rate \| Barclays Bank PLC
Interest rate	8.30%	8.30%	8.30%	8.30%
Notional contract amount \| $			$ 450
Total AT1 equity instruments	£ 263				263
AT1 equity instruments \| 4.375% Perpetual Subordinated Contingent Convertible Securities (USD1,500m) \| Fixed interest rate \| Barclays Bank PLC
Interest rate	4.375%	4.375%	4.375%	4.375%
Notional contract amount \| $				$ 1,500
Total AT1 equity instruments	£ 1,072				1,072
AT1 equity instruments \| 7.300% Perpetual Subordinated Contingent Convertible Securities (SGD400m) \| Fixed interest rate \| Barclays Bank PLC
Interest rate	7.30%	7.30%	7.30%	7.30%
Notional contract amount \| $			$ 400
Total AT1 equity instruments	£ 247				247
AT1 equity instruments \| 9.250% Perpetual Subordinated Contingent Convertible Securities \| Fixed interest rate \| Barclays Bank PLC
Interest rate	9.25%	9.25%	9.25%	9.25%
Total AT1 equity instruments	£ 866				866
AT1 equity instruments \| 8.000% Perpetual Subordinated Contingent Convertible Securities (USD2,000m) \| Fixed interest rate \| Barclays Bank PLC
Interest rate	8.00%	8.00%	8.00%	8.00%
Notional contract amount \| $				$ 2,000
Total AT1 equity instruments	£ 1,634				1,634
AT1 equity instruments \| 9.625% Perpetual Subordinated Contingent Convertible Securities (USD1,750m) \| Fixed interest rate \| Barclays Bank PLC
Interest rate	9.625%	9.625%	9.625%	9.625%
Notional contract amount \| $				$ 1,750
Total AT1 equity instruments	£ 1,386				1,386
AT1 equity instruments \| 5.400% Perpetual Subordinated Contingent Convertible Securities (SGD600m) \| Fixed interest rate \| Barclays Bank PLC
Interest rate	5.40%	5.40%	5.40%	5.40%
Notional contract amount \| $			$ 600
Total AT1 equity instruments	£ 352				352
AT1 equity instruments \| 8.500% Perpetual Subordinated Contingent Convertible Securities \| Fixed interest rate \| Barclays Bank PLC
Interest rate	8.50%	8.50%	8.50%	8.50%
Total AT1 equity instruments	£ 619				619
AT1 equity instruments \| 4.650% Perpetual Subordinated Contingent Convertible Securities (SGD500m) \| Fixed interest rate \| Barclays Bank PLC
Interest rate	4.65%	4.65%	4.65%	4.65%
Notional contract amount \| $			$ 500
Total AT1 equity instruments	£ 288				0
AT1 equity instruments \| 7.625% Perpetual Subordinated Contingent Convertible Securities (USD1,500m) \| Fixed interest rate \| Barclays Bank PLC
Interest rate	7.625%	7.625%	7.625%	7.625%
Notional contract amount \| $				$ 1,500
Total AT1 equity instruments	£ 1,174				0
AT1 equity instruments \| 6.125% Perpetual Subordinated Contingent Convertible Securities (EUR1,500m) \| Fixed interest rate \| Barclays Bank PLC
Interest rate	6.125%	6.125%	6.125%	6.125%
Notional contract amount \| €		€ 1,500
Total AT1 equity instruments	£ 1,308				£ 0