COMMITMENTS AND CONTINGENCIES - OTHER LITIGATION (Details) £ in Millions, $ in Millions		3 Months Ended	9 Months Ended
	Nov. 02, 2020 lawsuit proof_of_claim	Mar. 31, 2020 GBP (£)	Sep. 30, 2020 USD ($)	Oct. 01, 2014 USD ($)	Oct. 01, 2014 GBP (£)
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]
Damages awarded		£ 45	$ 58
Energy Future Holdings Corp. [Member] | Subsequent Event [Member]
Loss Contingencies [Line Items]
Number of lawsuits	275
Number of lawsuits filed	182
Number of proof of claims | proof_of_claim	28,000
R B S Sempra Commodities [Member]
Loss Contingencies [Line Items]
Equity losses on investment | $			$ 100
Maximum [Member] | R B S Sempra Commodities [Member] | HMRC VAT Claim [Member]
Loss Contingencies [Line Items]
VAT tax claim, penalty (as a percentage)				100.00%	100.00%