Debt securities in issue - Schedule of Debt Securities in Issue (Details) - GBP (£) £ in Millions |
Jun. 30, 2026 |
Dec. 31, 2025 |
|---|---|---|
| Disclosure of financial liabilities [line items] | ||
| Senior unsecured notes issued | £ 25,515 | £ 24,582 |
| Covered bonds | 12,706 | 11,264 |
| Commercial paper | 17,295 | 11,703 |
| Securitisation notes | 7,053 | 6,342 |
| Certificates of deposit issued | 4,475 | 2,484 |
| Debt instruments issued | 67,044 | 56,375 |
| Financial liabilities at fair value through profit or loss | ||
| Disclosure of financial liabilities [line items] | ||
| Senior unsecured notes issued | 4,221 | 4,226 |
| Covered bonds | 0 | 0 |
| Commercial paper | 0 | 0 |
| Securitisation notes | 17 | 17 |
| Certificates of deposit issued | 0 | 0 |
| Debt instruments issued | 4,238 | 4,243 |
| At amortised costs | ||
| Disclosure of financial liabilities [line items] | ||
| Senior unsecured notes issued | 21,294 | 20,356 |
| Covered bonds | 12,706 | 11,264 |
| Commercial paper | 17,295 | 11,703 |
| Securitisation notes | 7,036 | 6,325 |
| Certificates of deposit issued | 4,475 | 2,484 |
| Debt instruments issued | £ 62,806 | £ 52,132 |