GENERAL INFORMATION AND OTHER FINANCIAL DATA - CHANGES IN ACCUMULATED OTHER COMPREHENSIVE INCOME (Details) - USD ($)		3 Months Ended
		Mar. 31, 2018	Mar. 31, 2017	Jan. 01, 2018
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
AOCI, beginning balance	[1]	$ (626,000,000)
Cumulative-effect adjustment from change in accounting principle				$ (1,000,000)
Amounts reclassified from AOCI		(6,000,000)	$ 8,000,000
AOCI, ending balance		(545,000,000)
Foreign currency translation adjustments [Member]
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
AOCI, beginning balance		(420,000,000)	(527,000,000)
Cumulative-effect adjustment from change in accounting principle				0
OCI before reclassifications		24,000,000	46,000,000
Amounts reclassified from AOCI		0	0
Net OCI		24,000,000	46,000,000
AOCI, ending balance		(396,000,000)	(481,000,000)
Financial instruments [Member]
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
AOCI, beginning balance		(122,000,000)	(125,000,000)
Cumulative-effect adjustment from change in accounting principle				(3,000,000)
OCI before reclassifications		66,000,000	(2,000,000)
Amounts reclassified from AOCI		(8,000,000)	6,000,000
Net OCI		58,000,000	4,000,000
AOCI, ending balance		(67,000,000)	(121,000,000)
Pension and other postretirement benefits [Member]
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
AOCI, beginning balance		(84,000,000)	(96,000,000)
Cumulative-effect adjustment from change in accounting principle				0
OCI before reclassifications		0	0
Amounts reclassified from AOCI		2,000,000	2,000,000
Net OCI		2,000,000	2,000,000
AOCI, ending balance		(82,000,000)	(94,000,000)
Total accumulated other comprehensive income (loss) [Member]
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
AOCI, beginning balance		(626,000,000)	(748,000,000)
Cumulative-effect adjustment from change in accounting principle				$ (3,000,000)
OCI before reclassifications		90,000,000	44,000,000
Amounts reclassified from AOCI		(6,000,000)	8,000,000
Net OCI		84,000,000	52,000,000
AOCI, ending balance		(545,000,000)	(696,000,000)
San Diego Gas and Electric Company [Member]
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
AOCI, beginning balance	[1]	(8,000,000)
Amounts reclassified from AOCI		0	0
AOCI, ending balance		(8,000,000)
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]
AOCI, beginning balance		(8,000,000)	(8,000,000)
AOCI, ending balance		(8,000,000)	(8,000,000)
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]
AOCI, beginning balance		(8,000,000)	(8,000,000)
AOCI, ending balance		(8,000,000)	(8,000,000)
Southern California Gas Company [Member]
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
AOCI, beginning balance	[1]	(21,000,000)
Amounts reclassified from AOCI		0	0
AOCI, ending balance		(21,000,000)
Southern California Gas Company [Member] | Financial instruments [Member]
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
AOCI, beginning balance		(13,000,000)	(13,000,000)
AOCI, ending balance		(13,000,000)	(13,000,000)
Southern California Gas Company [Member] | Pension and other postretirement benefits [Member]
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
AOCI, beginning balance		(8,000,000)	(9,000,000)
AOCI, ending balance		(8,000,000)	(9,000,000)
Southern California Gas Company [Member] | Total accumulated other comprehensive income (loss) [Member]
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
AOCI, beginning balance		(21,000,000)	(22,000,000)
AOCI, ending balance		$ (21,000,000)	$ (22,000,000)

[1] Derived from audited financial statements.