Intangible Assets - Pre-publication - Additional Information (Detail) - GBP (£) £ in Millions	Dec. 31, 2017	Dec. 31, 2016
Disclosure of reconciliation of changes in intangible assets and goodwill [line items]
Intangible assets - pre-publication	£ 741	£ 1,024
More than 12 months past due date [member]
Disclosure of reconciliation of changes in intangible assets and goodwill [line items]
Intangible assets - pre-publication	£ 504	£ 694

Line items represent concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes of the table.

No definition available.

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