GENERAL INFORMATION AND OTHER FINANCIAL DATA - RECLASSIFICATION FROM ACCUMULATED OTHER COMPREHENSIVE INCOME (Details) - USD ($)	3 Months Ended			6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017		Jun. 30, 2018	Jun. 30, 2017
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Interest expense	$ (237,000,000)	$ (159,000,000)	[1]	$ (453,000,000)	$ (328,000,000)	[1]
Equity (losses) earnings	185,000,000	0		160,000,000	(8,000,000)
Other (expense) income, net	(54,000,000)	108,000,000	[1]	99,000,000	282,000,000	[1]
Equity (losses) earnings	(4,000,000)	18,000,000	[1]	(24,000,000)	13,000,000	[1]
Revenues: Energy-Related Businesses	374,000,000	336,000,000	[1]	738,000,000	669,000,000	[1]
(Loss) Income before income taxes and equity (losses) earnings of certain unconsolidated subsidiaries	(1,109,000,000)	397,000,000	[1]	(442,000,000)	1,149,000,000	[1]
Income tax benefit (expense)	583,000,000	(167,000,000)	[1]	294,000,000	(462,000,000)	[1]
(Earnings) Losses Attributable to Noncontrolling Interests	(5,000,000)	12,000,000	[1]	12,000,000	1,000,000	[1]
Earnings (losses)	(561,000,000)	259,000,000		(214,000,000)	700,000,000
Total reclassifications for the period, net of tax	10,000,000	1,000,000		4,000,000	9,000,000
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	8,000,000	0		0	6,000,000
Gain (Loss) on Pension and Other Postretirement Benefits [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Amortization of actuarial loss(2)	3,000,000	2,000,000		6,000,000	5,000,000
Pension and Other Postretirement Benefits [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Income tax expense	(1,000,000)	(1,000,000)		(2,000,000)	(2,000,000)
Total reclassifications for the period, net of tax	2,000,000	1,000,000		4,000,000	3,000,000
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]
(Loss) Income before income taxes and equity (losses) earnings of certain unconsolidated subsidiaries	19,000,000	3,000,000		3,000,000	15,000,000
Income tax benefit (expense)	(4,000,000)	(1,000,000)		(1,000,000)	(5,000,000)
Net of income tax	15,000,000	2,000,000		2,000,000	10,000,000
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	1,000,000	(1,000,000)		(1,000,000)	(4,000,000)
Equity (losses) earnings				5,000,000	9,000,000
Other (expense) income, net	18,000,000	0
Equity (losses) earnings	1,000,000	5,000,000
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	(1,000,000)	(1,000,000)		(1,000,000)	1,000,000
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	9,000,000
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) Losses Attributable to Noncontrolling Interests	(7,000,000)	(2,000,000)		(2,000,000)	(4,000,000)
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)	8,000,000	0		0	6,000,000
San Diego Gas and Electric Company [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Interest expense	(53,000,000)	(49,000,000)	[1]	(105,000,000)	(98,000,000)	[1]
Other (expense) income, net	25,000,000	19,000,000	[1]	53,000,000	41,000,000	[1]
(Loss) Income before income taxes and equity (losses) earnings of certain unconsolidated subsidiaries	188,000,000	207,000,000	[1]	413,000,000	454,000,000	[1]
Income tax benefit (expense)	(42,000,000)	(54,000,000)	[1]	(98,000,000)	(144,000,000)	[1]
(Earnings) Losses Attributable to Noncontrolling Interests	0	(4,000,000)	[1]	1,000,000	(6,000,000)	[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	1,000,000	3,000,000		4,000,000	6,000,000
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) Losses Attributable to Noncontrolling Interests	(1,000,000)	(3,000,000)		(4,000,000)	(6,000,000)
San Diego Gas and Electric Company [Member] | 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)				0	0
Southern California Gas Company [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Interest expense	(26,000,000)	(26,000,000)	[1]	(53,000,000)	(51,000,000)	[1]
Other (expense) income, net	13,000,000	24,000,000	[1]	46,000,000	38,000,000	[1]
(Loss) Income before income taxes and equity (losses) earnings of certain unconsolidated subsidiaries	57,000,000	78,000,000	[1]	341,000,000	379,000,000	[1]
Income tax benefit (expense)	(23,000,000)	(19,000,000)	[1]	(82,000,000)	(117,000,000)	[1]
Total reclassifications for the period, net of tax	1,000,000	1,000,000		1,000,000	1,000,000
Southern California Gas Company [Member] | 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	0	0		0	0
Southern California Gas Company [Member] | Gain (Loss) on Pension and Other Postretirement Benefits [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Amortization of actuarial loss(2)	1,000,000	1,000,000		1,000,000	1,000,000
Southern California Gas Company [Member] | Pension and Other Postretirement Benefits [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Total reclassifications for the period, net of tax	$ 1,000,000	$ 1,000,000		$ 1,000,000	$ 1,000,000

[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.