COMMITMENTS AND CONTINGENCIES - OTHER LITIGATION (Details) £ in Millions, $ in Millions	6 Months Ended
	Jun. 30, 2018 USD ($) lawsuit proof_of_claim	Jun. 30, 2018 GBP (£)	Aug. 01, 2018 lawsuit	Oct. 01, 2014 USD ($)	Oct. 01, 2014 GBP (£)
Loss Contingencies [Line Items]
Investment in RBS Sempra Commodities LLP | $	$ 65
HMRC VAT Claim [Member]
Loss Contingencies [Line Items]
VAT tax claim paid upon appeal				$ 138	£ 86
Filed claims amount	211	£ 160
Southern California Gas Company [Member] | Subsequent Event [Member] | Aliso Canyon Natural Gas Storage Facility Gas Leak [Member]
Loss Contingencies [Line Items]
Number of lawsuits			382
Plaintiffs [Member] | HMRC VAT Claim [Member]
Loss Contingencies [Line Items]
Filed claims amount	$ 106	£ 80
Energy Future Holdings Corp. [Member]
Loss Contingencies [Line Items]
Number of lawsuits	115
Number of proof of claims | proof_of_claim	28,000