LIABILITIES ARISING FROM NON-PARTICIPATING INVESTMENT CONTRACTS - Narrative (Details) - GBP (£) £ in Millions	Dec. 31, 2021	Dec. 31, 2020
LIABILITIES ARISING FROM NON-PARTICIPATING INVESTMENT CONTRACTS (Details) - Narrative [Line Items]
Contracts held with reinsurers	£ 759	£ 842
Non participating life insurance policy
LIABILITIES ARISING FROM NON-PARTICIPATING INVESTMENT CONTRACTS (Details) - Narrative [Line Items]
Contracts held with reinsurers	£ 3	£ 8

The amount of a cedant’s net contractual rights under a reinsurance contract.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Note Expiry date 2023-01-01
-Name IFRS
-Number 4
-IssueDate 2021-01-01
-Paragraph 37
-Subparagraph e
-URI http://eifrs.ifrs.org/eifrs/xifrs-link?type=IFRS&num=4&code=ifrs-tx-2021-en-b&anchor=para_37_e&doctype=Standard&book=b
-URIDate 2021-03-24

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