Trade and Other Receivables - Additional Information (Detail) £ in Millions	12 Months Ended
Dec. 31, 2018 GBP (£)
Disclosure of other provisions [abstract]
Impairment charges on accrued income assets	£ 0

The amount of impairment loss on receivables or contract assets arising from contracts with customers. [Refer: Contract assets; Impairment loss; Receivables from contracts with customers]

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Name IFRS
-Number 15
-IssueDate 2019-01-01
-Paragraph 113
-Subparagraph b
-URI http://eifrs.ifrs.org/eifrs/xifrs-link?type=IFRS&num=15&code=ifrs-tx-2019-en-r&anchor=para_113_b&doctype=Standard
-URIDate 2019-03-27

Name:	ifrs-full_ImpairmentLossOnReceivablesOrContractAssetsArisingFromContractsWithCustomers
Namespace Prefix:	ifrs-full_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration