Subordinated liabilities - Narrative (Details) - GBP (£) £ in Millions |
6 Months Ended | 12 Months Ended |
|---|---|---|
Jun. 30, 2025 |
Dec. 31, 2024 |
|
| Disclosure of detailed information about borrowings [line items] | ||
| Proceeds from issue of subordinated liabilities | £ 5,379 | £ 11,222 |
| Redemption of subordinated debt | 2,371 | £ 5,067 |
| Barclays Bank PLC loans issued intra-group Barclays PLC | Barclays PLC | ||
| Disclosure of detailed information about borrowings [line items] | ||
| Proceeds from issue of subordinated liabilities | 4,710 | |
| Redemption of subordinated debt | 2,256 | |
| 4.616% Fixed Rate Resetting Subordinated Callable Notes | Fixed interest rate | Barclays PLC | ||
| Disclosure of detailed information about borrowings [line items] | ||
| Proceeds from issue of subordinated liabilities | £ 669 | |
| Interest rate | 4.616% | |
| 3.750% Fixed Rate Resetting Subordinated Callable Notes | Fixed interest rate | Barclays PLC | ||
| Disclosure of detailed information about borrowings [line items] | ||
| Interest rate | 3.75% | |
| Redemption of subordinated debt | £ 115 |