REGULATORY MATTERS - GENERAL RATE CASE (Details) - USD ($) $ in Millions			1 Months Ended	3 Months Ended		12 Months Ended
	Oct. 06, 2017	Oct. 31, 2016	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016	Dec. 31, 2017	Sep. 30, 2016
Southern California Gas Company [Member]
General Rate Case [Line Items]
GRC requested revenue requirement	$ 2,989
GRC requested revenue requirement adjustment	533
Refund of tax memorandum account, pre-tax				$ 72
Refund of tax memorandum account, net of tax				(43)
Change in tax estimates, pre-tax				(11)
Change in tax estimates, net of tax				(6)	$ 6
Adjustment to revenue related to tax repairs deductions, pre-tax				(83)
Adjustment to revenue related to tax repairs deductions, net of tax				(49)
Southern California Gas Company [Member] | Year 2016 [Member]
General Rate Case [Line Items]
GRC revenue requirement			$ 2,204
Rate base adjustment						$ 38
Revenue requirement adjustment						$ 5
Change in income tax liability from prior year							$ (19)
Southern California Gas Company [Member] | Years 2017 and 2018 [Member]
General Rate Case [Line Items]
Change in GRC revenue requirement						3.50%
Z Factor Mechanism, Deductible Per Event						$ 5
Southern California Gas Company [Member] | Years 2012 through 2014 [Member]
General Rate Case [Line Items]
Regulatory liability			11		11
Southern California Gas Company [Member] | Year 2015 [Member]
General Rate Case [Line Items]
Amended requested change in rate		$ 32
Southern California Gas Company [Member] | General Rate Case [Member]
General Rate Case [Line Items]
Tracked income tax expense liability						65
San Diego Gas and Electric Company [Member]
General Rate Case [Line Items]
GRC requested revenue requirement	2,199
GRC requested revenue requirement adjustment	$ 217
Refund of tax memorandum account, pre-tax				37
Refund of tax memorandum account, net of tax				(22)
Change in tax estimates, pre-tax				(15)
Change in tax estimates, net of tax				(9)	9
Adjustment to revenue related to tax repairs deductions, pre-tax				(52)
Adjustment to revenue related to tax repairs deductions, net of tax				$ (31)
San Diego Gas and Electric Company [Member] | Year 2016 [Member]
General Rate Case [Line Items]
GRC revenue requirement			1,791
Rate base adjustment						55
Revenue requirement adjustment						7
Change in income tax liability from prior year							$ (5)
San Diego Gas and Electric Company [Member] | Years 2012 through 2014 [Member]
General Rate Case [Line Items]
Regulatory liability			$ 15		$ 15
San Diego Gas and Electric Company [Member] | Year 2015 [Member]
General Rate Case [Line Items]
Amended requested change in rate		$ 53
San Diego Gas and Electric Company [Member] | General Rate Case [Member]
General Rate Case [Line Items]
Tracked income tax expense liability						$ 69
Minimum [Member] | Southern California Gas Company [Member]
General Rate Case [Line Items]
GRC requested revenue requirement adjustment percentage	6.00%
Minimum [Member] | San Diego Gas and Electric Company [Member]
General Rate Case [Line Items]
GRC requested revenue requirement adjustment percentage	5.00%
Maximum [Member] | Southern California Gas Company [Member]
General Rate Case [Line Items]
GRC requested revenue requirement adjustment percentage	8.00%
Maximum [Member] | San Diego Gas and Electric Company [Member]
General Rate Case [Line Items]
GRC requested revenue requirement adjustment percentage	7.00%