LIABILITIES ARISING FROM INSURANCE CONTRACTS AND PARTICIPATING INVESTMENT CONTRACTS (Details) - Schedule of Liabilities for Insurance Contracts and Participating Investment Contracts - GBP (£) £ in Millions	Dec. 31, 2017	Dec. 31, 2016
LIABILITIES ARISING FROM INSURANCE CONTRACTS AND PARTICIPATING INVESTMENT CONTRACTS (Details) - Schedule of Liabilities for Insurance Contracts and Participating Investment Contracts [Line Items]
Insurance contracts	£ 103,413	£ 94,390
Participating investment contracts	15,447	20,112
Discounted cash flow [member]
LIABILITIES ARISING FROM INSURANCE CONTRACTS AND PARTICIPATING INVESTMENT CONTRACTS (Details) - Schedule of Liabilities for Insurance Contracts and Participating Investment Contracts [Line Items]
Insurance contracts	89,157	79,793
Participating investment contracts	13,673	13,984
Total	102,830	93,777
Discounted cash flow [member] | With-profit fund [Member]
LIABILITIES ARISING FROM INSURANCE CONTRACTS AND PARTICIPATING INVESTMENT CONTRACTS (Details) - Schedule of Liabilities for Insurance Contracts and Participating Investment Contracts [Line Items]
Insurance contracts	8,946	9,147
Participating investment contracts	8,481	8,860
Total	17,427	18,007
Discounted cash flow [member] | Non-profit fund [Member]
LIABILITIES ARISING FROM INSURANCE CONTRACTS AND PARTICIPATING INVESTMENT CONTRACTS (Details) - Schedule of Liabilities for Insurance Contracts and Participating Investment Contracts [Line Items]
Insurance contracts	80,211	70,646
Participating investment contracts	5,192	5,124
Total	£ 85,403	£ 75,770