Intangible Assets - Product Development - Additional Information (Detail) - GBP (£) £ in Millions |
12 Months Ended | ||
|---|---|---|---|
Dec. 31, 2025 |
Dec. 31, 2024 |
Dec. 31, 2023 |
|
| Product Development Assets [Member] | |||
| Disclosure of reconciliation of changes in intangible assets and goodwill [line items] | |||
| Intangible assets product development | £ 88 | £ 4 | £ 4 |
| Impairment | 88 | 4 | 4 |
| Asset Writeoffs Related To The Major Restructuring Programme [Member] | |||
| Disclosure of reconciliation of changes in intangible assets and goodwill [line items] | |||
| Intangible assets product development | 87 | 0 | 0 |
| Impairment | £ 87 | £ 0 | £ 0 |