Retirement benefits (Details) - GBP (£) £ in Billions |
Jun. 30, 2026 |
Dec. 31, 2025 |
Sep. 30, 2025 |
|---|---|---|---|
| Disclosure of fair value of plan assets [line items] | |||
| Surplus (deficit) in plan | £ 3.1 | £ 3.1 | |
| Defined benefit plans other than multi-employer plans, state plans and plans that share risks between entities under common control | Pension defined benefit plans | Country of domicile | |||
| Disclosure of fair value of plan assets [line items] | |||
| Surplus (deficit) in plan | £ 3.2 | £ 3.2 | |
| Barclays Bank PLC | Pension defined benefit plans | Country of domicile | |||
| Disclosure of fair value of plan assets [line items] | |||
| Surplus (deficit) in plan | £ 1.9 |