FINANCIAL ASSETS AT FAIR VALUE THROUGH PROFIT OR LOSS (Details) - Narrative - GBP (£) £ in Millions	Dec. 31, 2020	Dec. 31, 2019
FINANCIAL ASSETS AT FAIR VALUE THROUGH PROFIT OR LOSS (Details) - Narrative [Line Items]
Financial assets at fair value through profit or loss	£ 171,626	£ 160,189
Assets and liabilities held in unconsolidated collective investment vehicles	55,235	38,177
Types of insurance contracts
FINANCIAL ASSETS AT FAIR VALUE THROUGH PROFIT OR LOSS (Details) - Narrative [Line Items]
Financial assets at fair value through profit or loss	£ 145,905	£ 136,855

The amount of financial assets that are measured at fair value and for which gains (losses) are recognised in profit or loss. A financial asset shall be measured at fair value through profit or loss unless it is measured at amortised cost or at fair value through other comprehensive income. A gain (loss) on a financial asset measured at fair value shall be recognised in profit or loss unless it is part of a hedging relationship, it is an investment in an equity instrument for which the entity has elected to present gains and losses in other comprehensive income or it is a financial asset measured at fair value through other comprehensive income. [Refer: At fair value [member]; Financial assets]

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Name IFRS
-Number 7
-IssueDate 2020-01-01
-Paragraph 8
-Subparagraph a
-URI http://eifrs.ifrs.org/eifrs/xifrs-link?type=IFRS&num=7&code=ifrs-tx-2020-en-r&anchor=para_8_a&doctype=Standard
-URIDate 2020-01-01

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Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant