SIGNIFICANT ACCOUNTING POLICIES AND OTHER FINANCIAL DATA - RECLASSIFICATION FROM ACCUMULATED OTHER COMPREHENSIVE INCOME (Details) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Income (loss) from discontinued operations, net of income tax									$ 1,840	$ 328	$ 156
(Loss) gain on sale of assets									(3)	63	513
Interest expense									(1,081)	(1,077)	(886)
Equity earnings									1,015	580	175
Energy-related businesses									1,345	1,381	1,563
Other (expense) income, net									48	(77)	(58)
Income before income taxes									1,489	1,734	714
Income tax (expense) benefit									(249)	(315)	49
Income from continuing operations, net of income tax									2,255	1,999	938
Earnings attributable to noncontrolling interest									(172)	(164)	(76)
Total reclassifications for the period, net of tax	$ 414	$ 351	$ 2,239	$ 760	$ 447	$ 813	$ 354	$ 441
San Diego Gas and Electric Company [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Interest expense									(413)	(411)	(221)
Other (expense) income, net									(52)	(39)	(56)
Income before income taxes									1,014	945	849
Income tax (expense) benefit									(190)	(171)	(173)
Earnings attributable to noncontrolling interest					$ 0	$ (3)	$ (3)	$ (1)	0	(7)	(7)
Southern California Gas Company [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Interest expense									(158)	(141)	(115)
Other (expense) income, net									28	55	(15)
Income before income taxes									601	762	493
Income tax (expense) benefit									(96)	(120)	(92)
Reclassification out of Accumulated Other Comprehensive Income [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Total reclassifications for the period, net of tax									721	40	21
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]
Total reclassifications for the period, net of tax									1	1	4
Reclassification out of Accumulated Other Comprehensive Income [Member] | Southern California Gas Company [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Total reclassifications for the period, net of tax									2	1	2
Reclassification out of Accumulated Other Comprehensive Income [Member] | Foreign currency translation adjustments [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Income (loss) from discontinued operations, net of income tax									645	0	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									67	11	13
Income tax (expense) benefit									(19)	(2)	(4)
Income from continuing operations, net of income tax									48	9	9
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									1	0	(1)
Other (expense) income, net									11	(9)	(2)
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]
(Loss) gain on sale of assets									0	10	9
Interest expense									10	3	1
Equity earnings									46	3	9
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									0	3	7
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]
Equity earnings									0	2	(2)
Energy-related businesses									(1)	2	(1)
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)	(1)	(6)
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									0	(3)	(7)
Reclassification out of Accumulated Other Comprehensive Income [Member] | Financial instruments attributable to parent [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Total reclassifications for the period, net of tax									47	8	3
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]
Total reclassifications for the period, net of tax									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									0	1	1
Reclassification out of Accumulated Other Comprehensive Income [Member] | Amortization of actuarial loss [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Income (loss) from discontinued operations, net of income tax									6	1	1
Other (expense) income, net									8	12	11
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 (expense) income, net									1	0	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 (expense) income, net									1	1	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 (expense) income, net									4	3	2
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 (expense) income, net									1	1	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 (expense) income, net									1	0	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 (expense) income, net									22	28	12
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 (expense) income, net									0	0	4
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 (loss) from discontinued operations, net of income tax									(2)	0	0
Income before income taxes									40	44	26
Income tax (expense) benefit									(9)	(12)	(8)
Income from continuing operations, net of income tax									29	32	18
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									2	1	5
Income tax (expense) benefit									(1)	0	(1)
Income from continuing operations, net of income tax									1	1	4
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									2	1	1
Income tax (expense) benefit									0	(1)	0
Income from continuing operations, net of income tax									$ 2	$ 0	$ 1