GENERAL INFORMATION AND OTHER FINANCIAL DATA - RECLASSIFICATION FROM ACCUMULATED OTHER COMPREHENSIVE INCOME (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Interest expense	$ (216)	$ (169)	[1]
Other income, net	153	174	[1]
Equity losses	(20)	(5)	[1]
Revenues: Energy-Related Businesses	364	333	[1]
Income before income taxes and equity (losses) earnings of certain unconsolidated subsidiaries	667	752	[1]
Income Tax Benefit (Expense)	(289)	(295)	[1]
Earnings Attributable to Noncontrolling Interests	17	(11)	[1]
Earnings (losses)	347	441
Total reclassifications for the period, net of tax	(6)	8
Gains (Losses) on Cash Flow hedges Attributable to Parent [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Total reclassifications for the period, net of tax	(8)	6
Gain (Loss) on Pension and Other Postretirement Benefits [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Amortization of actuarial loss(2)	3	3
Pension and Other Postretirement Benefits [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Income tax expense	(1)	(1)
Total reclassifications for the period, net of tax	2	2
Reclassification out of Accumulated Other Comprehensive Income [Member] | Gains (Losses) on Cash Flow hedges [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Income before income taxes and equity (losses) earnings of certain unconsolidated subsidiaries	(16)	12
Income Tax Benefit (Expense)	3	(4)
Net of income tax	(13)	8
Reclassification out of Accumulated Other Comprehensive Income [Member] | Gains (Losses) on Cash Flow hedges [Member] | Interest rate and foreign exchange instruments [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Interest expense	(2)	(3)
Other income, net	(18)	0
Equity losses	4	4
Reclassification out of Accumulated Other Comprehensive Income [Member] | Gains (Losses) on Cash Flow hedges [Member] | Foreign exchange instruments [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Revenues: Energy-Related Businesses	0	2
Reclassification out of Accumulated Other Comprehensive Income [Member] | Gains (Losses) on Cash Flow hedges [Member] | Commodity contracts not subject to rate recovery [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Revenues: Energy-Related Businesses	0	9
Reclassification out of Accumulated Other Comprehensive Income [Member] | Gains (Losses) on Cash Flow hedges Attributable to Noncontrolling Interests [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Earnings Attributable to Noncontrolling Interests	5	(2)
Reclassification out of Accumulated Other Comprehensive Income [Member] | Gains (Losses) on Cash Flow hedges Attributable to Parent [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Earnings (losses)	(8)	6
San Diego Gas and Electric Company [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Interest expense	(52)	(49)	[1]
Other income, net	28	22	[1]
Income before income taxes and equity (losses) earnings of certain unconsolidated subsidiaries	225	247	[1]
Income Tax Benefit (Expense)	(56)	(90)	[1]
Earnings Attributable to Noncontrolling Interests	1	(2)	[1]
Total reclassifications for the period, net of tax	0	0
San Diego Gas and Electric Company [Member] | Reclassification out of Accumulated Other Comprehensive Income [Member] | Gains (Losses) on Cash Flow hedges [Member] | Interest rate instruments [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Interest expense	3	3
San Diego Gas and Electric Company [Member] | Reclassification out of Accumulated Other Comprehensive Income [Member] | Gains (Losses) on Cash Flow hedges Attributable to Noncontrolling Interests [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Earnings Attributable to Noncontrolling Interests	(3)	(3)
Southern California Gas Company [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Interest expense	(27)	(25)	[1]
Other income, net	33	14	[1]
Income before income taxes and equity (losses) earnings of certain unconsolidated subsidiaries	284	301	[1]
Income Tax Benefit (Expense)	(59)	(98)	[1]
Total reclassifications for the period, net of tax	$ 0	$ 0

[1] As adjusted for the retrospective adoption of ASU 2017-07, which we discuss in Note 2, and a reclassification to conform to current year presentation, which we discuss in Note 1.