GENERAL INFORMATION AND OTHER FINANCIAL DATA - RECLASSIFICATION FROM ACCUMULATED OTHER COMPREHENSIVE INCOME (Details) - USD ($)	3 Months Ended			9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017		Sep. 30, 2018	Sep. 30, 2017
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Interest expense	$ (232,000,000)	$ (165,000,000)	[1]	$ (685,000,000)	$ (493,000,000)	[1]
Other income, net	97,000,000	40,000,000	[1]	196,000,000	322,000,000	[1]
Equity earnings	74,000,000	13,000,000	[1]	50,000,000	26,000,000	[1]
Energy-related businesses	480,000,000	402,000,000	[1]	1,218,000,000	1,071,000,000	[1]
(Loss) Income before income taxes and equity (losses) earnings of certain unconsolidated subsidiaries	427,000,000	5,000,000	[1]	(15,000,000)	1,154,000,000	[1]
Income tax benefit (expense)	(167,000,000)	84,000,000	[1]	127,000,000	(378,000,000)	[1]
Earnings attributable to noncontrolling interest	(24,000,000)	(45,000,000)	[1]	(12,000,000)	(44,000,000)	[1]
Total reclassifications for the period, net of tax	4,000,000	5,000,000		8,000,000	14,000,000
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	(4,000,000)	(2,000,000)		(4,000,000)	4,000,000
Gain (Loss) on Pension and Other Postretirement Benefits [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Amortization	9,000,000	11,000,000		15,000,000	16,000,000
Accumulated Defined Benefit Plans Adjustment, Net Prior Service Attributable to Parent [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Amortization	1,000,000	0		1,000,000	0
Pension and Other Postretirement Benefits [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Amortization	10,000,000	11,000,000		16,000,000	16,000,000
Income tax expense	(2,000,000)	(4,000,000)		(4,000,000)	(6,000,000)
Total reclassifications for the period, net of tax	8,000,000	7,000,000		12,000,000	10,000,000
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	(8,000,000)	(2,000,000)		(5,000,000)	13,000,000
Income tax benefit (expense)	4,000,000	1,000,000		3,000,000	(4,000,000)
Net of income tax	(4,000,000)	(1,000,000)		(2,000,000)	9,000,000
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)	(4,000,000)
Other income, net	(11,000,000)	0		(11,000,000)	0
Equity earnings	3,000,000	0		8,000,000	9,000,000
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]
Energy-related businesses	0	(2,000,000)		(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]
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 attributable to noncontrolling interest	0	(1,000,000)		(2,000,000)	(5,000,000)
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)	(4,000,000)	(2,000,000)		(4,000,000)	4,000,000
San Diego Gas and Electric Company [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Interest expense	(56,000,000)	(53,000,000)	[1]	(161,000,000)	(151,000,000)	[1]
Other income, net	24,000,000	20,000,000	[1]	77,000,000	61,000,000	[1]
(Loss) Income before income taxes and equity (losses) earnings of certain unconsolidated subsidiaries	269,000,000	(91,000,000)	[1]	682,000,000	363,000,000	[1]
Income tax benefit (expense)	(53,000,000)	72,000,000	[1]	(151,000,000)	(72,000,000)	[1]
Earnings attributable to noncontrolling interest	(11,000,000)	(9,000,000)	[1]	(10,000,000)	(15,000,000)	[1]
Total reclassifications for the period, net of tax	0	1,000,000		0	1,000,000
San Diego Gas and Electric Company [Member] | Gain (Loss) on Pension and Other Postretirement Benefits [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Amortization	0	1,000,000		0	1,000,000
San Diego Gas and Electric 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
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	2,000,000	3,000,000		6,000,000	9,000,000
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 attributable to noncontrolling interest	(2,000,000)	(3,000,000)		(6,000,000)	(9,000,000)
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		0	0
Southern California Gas Company [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Interest expense	(29,000,000)	(26,000,000)	[1]	(82,000,000)	(77,000,000)	[1]
Other income, net	3,000,000	13,000,000	[1]	49,000,000	51,000,000	[1]
(Loss) Income before income taxes and equity (losses) earnings of certain unconsolidated subsidiaries	(21,000,000)	(7,000,000)	[1]	320,000,000	372,000,000	[1]
Income tax benefit (expense)	$ 7,000,000	$ 14,000,000	[1]	(75,000,000)	(103,000,000)	[1]
Total reclassifications for the period, net of tax				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
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				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] 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.