GENERAL INFORMATION AND OTHER FINANCIAL DATA - CHANGES IN ACCUMULATED OTHER COMPREHENSIVE INCOME (Details) - USD ($) $ in Millions		3 Months Ended
		Mar. 31, 2020	Mar. 31, 2019	Dec. 31, 2019	Dec. 31, 2018
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Beginning balance	[1]	$ 19,929
OCI before reclassifications		(276)	$ (12)
Cumulative-effect adjustment from change in accounting principle				$ (9)	$ 15
Amounts reclassified from AOCI		25	1
Net OCI		(251)	(11)
Ending balance		20,117
Foreign currency translation adjustments [Member]
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Beginning balance		(607)	(564)
OCI before reclassifications		(138)	32
Cumulative-effect adjustment from change in accounting principle					0
Amounts reclassified from AOCI		0	0
Net OCI		(138)	32
Ending balance		(745)	(532)
Financial instruments [Member]
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Beginning balance		(215)	(82)
OCI before reclassifications		(154)	(45)
Cumulative-effect adjustment from change in accounting principle					(25)
Amounts reclassified from AOCI		19	(1)
Net OCI		(135)	(46)
Ending balance		(350)	(153)
Pension and other postretirement benefits [Member]
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Beginning balance		(117)	(118)
OCI before reclassifications		16	1
Cumulative-effect adjustment from change in accounting principle					(17)
Amounts reclassified from AOCI		6	2
Net OCI		22	3
Ending balance		(95)	(132)
Total accumulated other comprehensive income (loss) [Member]
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Beginning balance		(939)	(764)
Cumulative-effect adjustment from change in accounting principle					(42)
Ending balance		(1,190)	(817)
San Diego Gas and Electric Company [Member]
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Beginning balance	[1]	7,100
Cumulative-effect adjustment from change in accounting principle					0
Ending balance		7,162
San Diego Gas and Electric Company [Member] | Pension and other postretirement benefits [Member]
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Beginning balance		(16)	(10)
Cumulative-effect adjustment from change in accounting principle					(2)
Ending balance		(16)	(12)
San Diego Gas and Electric Company [Member] | Total accumulated other comprehensive income (loss) [Member]
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Beginning balance		(16)	(10)
Cumulative-effect adjustment from change in accounting principle					(2)
Ending balance		(16)	(12)
Southern California Gas Company [Member]
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Beginning balance	[1]	4,748
Cumulative-effect adjustment from change in accounting principle					(2)
Ending balance		5,051
Southern California Gas Company [Member] | Financial instruments [Member]
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Beginning balance		(13)	(12)
Cumulative-effect adjustment from change in accounting principle					(2)
Ending balance		(13)	(14)
Southern California Gas Company [Member] | Pension and other postretirement benefits [Member]
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Beginning balance		(10)	(8)
Cumulative-effect adjustment from change in accounting principle					(2)
Ending balance		(10)	(10)
Southern California Gas Company [Member] | Total accumulated other comprehensive income (loss) [Member]
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Beginning balance		(23)	(20)
Cumulative-effect adjustment from change in accounting principle					$ (4)
Ending balance		$ (23)	$ (24)

[1] Derived from audited financial statements.