ACQUISITION AND DIVESTITURE ACTIVITY - DIVESTITURES (Details) $ in Millions		1 Months Ended				3 Months Ended		9 Months Ended
	Sep. 12, 2016 USD ($)	May 31, 2016 USD ($)	Apr. 30, 2016	Mar. 31, 2016 USD ($)	Apr. 30, 2015 USD ($) MW	Sep. 30, 2016 USD ($)	Mar. 31, 2016 USD ($)	Sep. 30, 2016 USD ($)	Sep. 30, 2015 USD ($)	Mar. 29, 2016
Schedule of Equity Method Investments [Line Items]
Debt assumed								$ 448	$ 2
Impairment of equity method investment								131
Impairment of equity method investment after-tax								111
Sempra Natural Gas [Member] | Rockies Express [Member]
Schedule of Equity Method Investments [Line Items]
Ownership percentage		25.00%		25.00%			25.00%			25.00%
Proceeds from sale of equity method investment		$ 443		$ 440
Carrying value of equity method investment				484			$ 484
Fair value of equity method investment				$ 440			440
Impairment of equity method investment							44	44
Impairment of equity method investment after-tax							$ 27	27
Sempra Natural Gas [Member] | Energy South [Member]
Schedule of Equity Method Investments [Line Items]
Pre-tax gain on sale								130
After-tax gain on sale								$ 78
Sempra Natural Gas [Member] | Mesquite Power [Member]
Schedule of Equity Method Investments [Line Items]
Pre-tax gain on sale									61
After-tax gain on sale									$ 36
Proceeds from divestiture of businesses					$ 347
Power generating capacity | MW					625
Disposed of by Sale [Member] | Sempra Natural Gas [Member] | Energy South [Member]
Schedule of Equity Method Investments [Line Items]
Percentage of ownership before transaction			100.00%
Cash proceeds on sale	$ 318
Debt assumed	67
Pre-tax gain on sale	130					$ 130
After-tax gain on sale						$ 78
Proceeds from sale, net of transaction costs	304
Disposal Group, Including Discontinued Operation, Assets, Current [Abstract]
Cash	(2)
Inventory	(3)
Other current assets	(14)
Disposal Group, Including Discontinued Operation, Assets, Noncurrent [Abstract]
Regulatory assets	(12)
Goodwill	(72)
Other assets	(53)
Property, plant and equipment, net	(199)
Disposal Group, Including Discontinued Operation, Liabilities, Current [Abstract]
Accounts payable	12
Other current liabilities	13
Disposal Group, Including Discontinued Operation, Liabilities, Noncurrent [Abstract]
Long-term debt	67
Deferred income taxes	36
Regulatory liabilities	23
Asset retirement obligations	12
Other liabilities	$ 18