SIGNIFICANT ACCOUNTING POLICIES AND OTHER FINANCIAL DATA - RECLASSIFICATION FROM ACCUMULATED OTHER COMPREHENSIVE INCOME (Details) - USD ($) $ in Millions	1 Months Ended	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017		Dec. 31, 2016
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Interest expense										$ (925)	$ (659)	[1]	$ (553)	[1]
Other income, net										72	233	[1]	138	[1]
Gain on sale of assets	$ 513									524	3	[1]	134	[1]
Equity earnings										176	76	[1]	84	[1]
Remeasurement of equity method investment										0	0	[1]	617	[1]
Energy-related businesses										1,641	1,431	[1]	922	[1]
Income before income taxes										1,046	1,551	[1]	1,824	[1]
Income tax (expense) benefit										(96)	(1,276)	[1]	(389)	[1]
(Earnings) losses attributable to noncontrolling interest										(76)	(94)	[1]	(148)	[1]
Earnings attributable to common shares		$ 864	$ 274	$ (561)	$ 347	$ (501)	$ 57	$ 259	$ 441
Reclassification from AOCI, Net of taxes										21	19		18
San Diego Gas and Electric Company [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Interest expense										(221)	(203)	[1]	(195)	[1]
Other income, net										56	70	[1]	64	[1]
Income before income taxes										849	576	[1]	845	[1]
Income tax (expense) benefit										(173)	(155)	[1]	(280)	[1]
(Earnings) losses attributable to noncontrolling interest		$ 3	$ (11)	$ 0	$ 1	$ 1	$ (9)	$ (4)	$ (2)	(7)	(14)	[1]	5	[1]
Reclassification from AOCI, Net of taxes										4	1		1
Southern California Gas Company [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Interest expense										(115)	(102)	[1]	(97)	[1]
Other income, net										15	31	[1]	38	[1]
Income before income taxes										493	557	[1]	493	[1]
Income tax (expense) benefit										(92)	(160)	[1]	(143)	[1]
Reclassification from AOCI, Net of taxes										2	1		1
Financial instruments attributable to parent [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Reclassification from AOCI, Net of taxes										3	7		19
Financial instruments attributable to parent [Member] | Southern California Gas Company [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Reclassification from AOCI, Net of taxes										1	0		1
Pension and other postretirement benefits [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Reclassification from AOCI, Net of taxes										18	12		6
Pension and other postretirement benefits [Member] | San Diego Gas and Electric Company [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Reclassification from AOCI, Net of taxes										4	1		1
Pension and other postretirement benefits [Member] | Southern California Gas Company [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Reclassification from AOCI, Net of taxes										1	1		0
Reclassification out of Accumulated Other Comprehensive Income [Member] | Financial instruments [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Income before income taxes										13	23		33
Income tax (expense) benefit										(4)	(6)		(6)
Net of income tax										9	17		27
Reclassification out of Accumulated Other Comprehensive Income [Member] | Financial instruments [Member] | Interest rate and foreign exchange instruments [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Interest expense										0	(4)		17
Other income, net										(2)	0		0
Equity earnings										7	20		15
Remeasurement of equity method investment										0	0		7
Reclassification out of Accumulated Other Comprehensive Income [Member] | Financial instruments [Member] | Interest rate instruments [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Gain on sale of assets										9	0		0
Reclassification out of Accumulated Other Comprehensive Income [Member] | Financial instruments [Member] | Interest rate instruments [Member] | San Diego Gas and Electric Company [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Interest expense										7	13		12
Reclassification out of Accumulated Other Comprehensive Income [Member] | Financial instruments [Member] | Foreign exchange instruments [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Energy-related businesses										(1)	(2)		0
Reclassification out of Accumulated Other Comprehensive Income [Member] | Financial instruments [Member] | Commodity Contracts Not Subject To Rate Recovery [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Energy-related businesses										0	9		(6)
Reclassification out of Accumulated Other Comprehensive Income [Member] | Financial instruments attributable to Noncontrolling interests [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
(Earnings) losses attributable to noncontrolling interest										(6)	(10)		(15)
Reclassification out of Accumulated Other Comprehensive Income [Member] | Financial instruments attributable to Noncontrolling interests [Member] | San Diego Gas and Electric Company [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
(Earnings) losses attributable to noncontrolling interest										(7)	(13)		(12)
Reclassification out of Accumulated Other Comprehensive Income [Member] | Financial instruments attributable to parent [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Earnings attributable to common shares										3	7		12
Reclassification out of Accumulated Other Comprehensive Income [Member] | Financial instruments attributable to parent [Member] | San Diego Gas and Electric Company [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Earnings attributable to common shares										0	0		0
Reclassification out of Accumulated Other Comprehensive Income [Member] | Financial instruments attributable to parent [Member] | Interest rate instruments [Member] | Southern California Gas Company [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Interest expense										1	0		1
Reclassification out of Accumulated Other Comprehensive Income [Member] | Amortization of actuarial loss [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Other income, net										12	10		10
Reclassification out of Accumulated Other Comprehensive Income [Member] | Amortization of actuarial loss [Member] | San Diego Gas and Electric Company [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Other income, net										1	1		1
Reclassification out of Accumulated Other Comprehensive Income [Member] | Amortization of prior service cost [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Other income, net										2	1		1
Reclassification out of Accumulated Other Comprehensive Income [Member] | Amortization of prior service cost [Member] | Southern California Gas Company [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Other income, net										1	1		0
Reclassification out of Accumulated Other Comprehensive Income [Member] | Accumulated Defined Benefit Plans Adjustment, Net Settlements Attributable to Parent [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Other income, net										12	8		0
Reclassification out of Accumulated Other Comprehensive Income [Member] | Accumulated Defined Benefit Plans Adjustment, Net Settlements Attributable to Parent [Member] | San Diego Gas and Electric Company [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Other income, net										4	0		0
Reclassification out of Accumulated Other Comprehensive Income [Member] | Pension and other postretirement benefits [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Income before income taxes										26	19		11
Income tax (expense) benefit										(8)	(7)		(5)
Net of income tax										18	12		6
Reclassification out of Accumulated Other Comprehensive Income [Member] | Pension and other postretirement benefits [Member] | San Diego Gas and Electric Company [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Income before income taxes										5	1		1
Income tax (expense) benefit										(1)	0		0
Net of income tax										$ 4	$ 1		$ 1

[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.