COMMITMENTS AND CONTINGENCIES - OTHER LITIGATION (Details) £ in Millions, $ in Millions		9 Months Ended
	Jul. 20, 2018 GBP (£)	Sep. 30, 2018 USD ($) proof_of_claim lawsuit	Sep. 30, 2018 GBP (£)	Nov. 02, 2018 lawsuit	Oct. 01, 2014 USD ($)	Oct. 01, 2014 GBP (£)
HMRC VAT Claim [Member]
Loss Contingencies [Line Items]
Filed claims amount | $		$ 209
Southern California Gas Company [Member] | Subsequent Event [Member] | Aliso Canyon Natural Gas Storage Facility Gas Leak [Member]
Loss Contingencies [Line Items]
Number of lawsuits | lawsuit				388
R B S Sempra Commodities [Member]
Loss Contingencies [Line Items]
Investment in RBS Sempra Commodities LLP | $		65
R B S Sempra Commodities [Member] | HMRC VAT Claim [Member]
Loss Contingencies [Line Items]
VAT tax claim paid upon appeal					$ 138	£ 86
Plaintiffs [Member] | HMRC VAT Claim [Member]
Loss Contingencies [Line Items]
Filed claims amount		$ 104	£ 80
Energy Future Holdings Corp. [Member]
Loss Contingencies [Line Items]
Number of lawsuits | lawsuit		115
Number of proof of claims | proof_of_claim		28,000
Pending Litigation [Member] | HMRC VAT Claim [Member]
Loss Contingencies [Line Items]
Filed claims amount	£ 143	$ 186	£ 160