SECURITISATIONS AND COVERED BONDS (Details) - Securitisation programme [Member] - GBP (£) £ in Millions	Dec. 31, 2017	Dec. 31, 2016
SECURITISATIONS AND COVERED BONDS (Details) [Line Items]
Restricted cash and cash equivalents	£ 3,507	£ 9,018
Liquidity Facilities To Support Structured Entities	£ 95	£ 373

The amount of cash and cash equivalents whose use or withdrawal is restricted. [Refer: Cash and cash equivalents]

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Name IAS
-Number 1
-IssueDate 2016-01-13
-Paragraph 55
-URI http://eifrs.ifrs.org/eifrs/XBRL?type=IAS&num=1&date=2016-03-30&anchor=para_55&doctype=Standard
-URIDate 2016-03-31

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