COMMITMENTS AND CONTINGENCIES - OTHER LITIGATION (Details) - HMRC VAT Claim [Member] £ in Millions, $ in Millions	Mar. 31, 2017 USD ($)	Dec. 31, 2015 GBP (£)	Oct. 01, 2014 GBP (£)
Loss Contingencies [Line Items]
VAT tax claim paid upon appeal | £		£ 73	£ 86
Investment in RBS Sempra commodities LLP | $	$ 67