Leases - Summary of the present value of the group's finance lease obligations is as follows (Detail) - GBP (£) £ in Millions	Dec. 31, 2019	Dec. 31, 2018
Disclosure of present value of finance lease obligations [line items]
Net investment in finance lease receivable	£ 196	£ 5
Not later than one year [member]
Disclosure of present value of finance lease obligations [line items]
Net investment in finance lease receivable		3
Later than one year and not later than five years
Disclosure of present value of finance lease obligations [line items]
Net investment in finance lease receivable		£ 2

The gross investment in the finance lease discounted at the interest rate implicit in the lease. Finance lease is a lease that transfers substantially all the risks and rewards incidental to ownership of an underlying asset. Gross investment in the finance lease is the sum of: (a) the lease payments receivable by a lessor under a finance lease; and (b) any unguaranteed residual value accruing to the lessor. Interest rate implicit in the lease is the rate of interest that causes the present value of (a) the lease payments and (b) the unguaranteed residual value to equal to the sum of (i) the fair value of the underlying asset and (ii) the initial direct costs of the lessor.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Name IFRS
-Number 16
-IssueDate 2019-01-01
-Paragraph 94
-URI http://eifrs.ifrs.org/eifrs/xifrs-link?type=IFRS&num=16&code=ifrs-tx-2019-en-r&anchor=para_94&doctype=Standard
-URIDate 2019-03-27

Name:	ifrs-full_NetInvestmentInFinanceLease
Namespace Prefix:	ifrs-full_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant