FINANCIAL INSTRUMENTS - Additional Information (Details) - GBP (£) £ in Millions |
6 Months Ended | |
|---|---|---|
Jun. 30, 2026 |
Jun. 30, 2025 |
|
| Disclosure Of Fair Value Measurement Of Assets And Liabilities [Abstract] | ||
| Transfers out of Level 1 into Level 2 of fair value hierarchy, assets | £ 0 | £ 0 |
| Transfers out of Level 2 into Level 1 of fair value hierarchy, assets | 0 | 0 |
| Transfers out of Level 1 into Level 2 of fair value hierarchy, liabilities | 0 | 0 |
| Transfers out of Level 2 into Level 1 of fair value hierarchy, liabilities | £ 0 | £ 0 |