COMMITMENTS AND CONTINGENCIES - OTHER LITIGATION (Details) proof_of_claim in Thousands, £ in Millions, $ in Millions		6 Months Ended
	Jul. 29, 2019 lawsuit	Jun. 30, 2019 USD ($) proof_of_claim	Jun. 30, 2019 GBP (£) proof_of_claim	Sep. 30, 2018 USD ($)	Oct. 01, 2014 USD ($)	Oct. 01, 2014 GBP (£)
R B S Sempra Commodities [Member]
Loss Contingencies [Line Items]
Investment in RBS Sempra Commodities LLP | $				$ 65.0
R B S Sempra Commodities [Member] | HMRC VAT Claim [Member]
Loss Contingencies [Line Items]
VAT tax claim paid upon appeal					$ 138.0	£ 86.0
Plaintiffs [Member] | HMRC VAT Claim [Member]
Loss Contingencies [Line Items]
Filed claims amount		$ 91.0	£ 71.5
Energy Future Holdings Corp. [Member]
Loss Contingencies [Line Items]
Number of proof of claims | proof_of_claim		28	28
Energy Future Holdings Corp. [Member] | Subsequent Event [Member]
Loss Contingencies [Line Items]
Number of lawsuits	111
Number of lawsuits filed	1,685