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, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Interest expense										$ (1,077)	$ (886)	$ (622)
Other income, net										(77)	(58)	(220)
Gain on sale of assets	$ 513									63	513	2
Equity earnings										580	175	72
Energy-related businesses										1,381	1,563	1,350
(Loss) income from discontinued operations, net of income tax		$ (71)	$ (256)	$ (78)	$ 42	$ (51)	$ (54)	$ (55)	$ (28)	(328)	(156)	58
Income before income taxes										1,734	714	1,248
Income tax (expense) benefit										(315)	49	(938)
Net of income tax										1,999	938	382
Earnings attributable to noncontrolling interest										(164)	(76)	(94)
Earnings attributable to common shares		447	813	354	441	864	274	(561)	347
San Diego Gas and Electric Company [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Interest expense										(411)	(221)	(203)
Other income, net										(39)	(56)	(70)
Income before income taxes										945	849	576
Income tax (expense) benefit										(171)	(173)	(155)
Earnings attributable to noncontrolling interest		$ 0	$ (3)	$ (3)	$ (1)	$ 3	$ (11)	$ 0	$ 1	(7)	(7)	(14)
Southern California Gas Company [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Interest expense										(141)	(115)	(102)
Other income, net										55	(15)	(31)
Income before income taxes										762	493	557
Income tax (expense) benefit										(120)	(92)	(160)
Reclassification out of Accumulated Other Comprehensive Income [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Earnings attributable to common shares										40	21	19
Reclassification out of Accumulated Other Comprehensive Income [Member] | San Diego Gas and Electric Company [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Earnings attributable to common shares										1	4	1
Reclassification out of Accumulated Other Comprehensive Income [Member] | Southern California Gas Company [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Earnings attributable to common shares										1	2	1
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										11	13	23
Income tax (expense) benefit										(2)	(4)	(6)
Net of income tax										9	9	17
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										3	0	(4)
Other income, net										(9)	(2)	0
Equity earnings										5	7	20
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										10	9	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										3	7	13
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										2	(1)	(2)
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	0	9
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 attributable to noncontrolling interest										(1)	(6)	(10)
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 attributable to noncontrolling interest										(3)	(7)	(13)
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										8	3	7
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	1	0
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	11	10
(Loss) income from discontinued operations, net of income tax										1	1	0
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										0	1	1
Reclassification out of Accumulated Other Comprehensive Income [Member] | Amortization of actuarial loss [Member] | Southern California Gas Company [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Other income, net										1	0	0
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										3	2	1
Reclassification out of Accumulated Other Comprehensive Income [Member] | Amortization of prior service cost [Member] | San Diego Gas and Electric Company [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Other income, net										1	0	0
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										0	1	1
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										28	12	8
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										0	4	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										44	26	19
Income tax (expense) benefit										(12)	(8)	(7)
Net of income tax										32	18	12
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										1	5	1
Income tax (expense) benefit										0	(1)	0
Net of income tax										1	4	1
Reclassification out of Accumulated Other Comprehensive Income [Member] | Pension and other postretirement benefits [Member] | Southern California Gas Company [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Income before income taxes										1	1	1
Income tax (expense) benefit										(1)	0	0
Net of income tax										$ 0	$ 1	$ 1