SIGNIFICANT ACCOUNTING POLICIES AND OTHER FINANCIAL DATA - CHANGES IN ACCUMULATED OTHER COMPREHENSIVE INCOME (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Jan. 01, 2019	Jan. 01, 2018
Accumulated Other Comprehensive Income (Loss) [Line Items]
AOCI, beginning balance	$ 17,138
AOCI, ending balance	19,929	$ 17,138
Cumulative-effect adjustment from change in accounting principle				$ 15	$ (1)
San Diego Gas and Electric Company [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
AOCI, beginning balance	6,015
AOCI, ending balance	7,100	6,015
Cumulative-effect adjustment from change in accounting principle		0
Southern California Gas Company [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
AOCI, beginning balance	4,258
AOCI, ending balance	4,748	4,258
Cumulative-effect adjustment from change in accounting principle		(2)
Foreign currency translation adjustments [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
AOCI, beginning balance	(564)	(420)	$ (527)
OCI before reclassifications	(43)	(144)	107
Amounts reclassified from AOCI	0	0	0
Total other comprehensive income (loss)	(43)	(144)	107
AOCI, ending balance	(607)	(564)	(420)
Cumulative-effect adjustment from change in accounting principle		0	0
Financial instruments [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
AOCI, beginning balance	(82)	(122)	(125)
OCI before reclassifications	(116)	40	(4)
Amounts reclassified from AOCI	8	3	7
Total other comprehensive income (loss)	(108)	43	3
AOCI, ending balance	(215)	(82)	(122)
Cumulative-effect adjustment from change in accounting principle		(25)	(3)
Financial instruments [Member] | Southern California Gas Company [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
AOCI, beginning balance	(12)	(13)	(13)
OCI before reclassifications	0	0
Amounts reclassified from AOCI	1	1	0
Total other comprehensive income (loss)	1	1	0
AOCI, ending balance	(13)	(12)	(13)
Cumulative-effect adjustment from change in accounting principle		(2)
Pension and other postretirement benefits [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
AOCI, beginning balance	(118)	(84)	(96)
OCI before reclassifications	(18)	(52)	0
Amounts reclassified from AOCI	36	18	12
Total other comprehensive income (loss)	18	(34)	12
AOCI, ending balance	(117)	(118)	(84)
Cumulative-effect adjustment from change in accounting principle		(17)	0
Pension and other postretirement benefits [Member] | San Diego Gas and Electric Company [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
AOCI, beginning balance	(10)	(8)	(8)
OCI before reclassifications	(5)	(6)	(1)
Amounts reclassified from AOCI	1	4	1
Total other comprehensive income (loss)	(4)	(2)	0
AOCI, ending balance	(16)	(10)	(8)
Cumulative-effect adjustment from change in accounting principle		(2)
Pension and other postretirement benefits [Member] | Southern California Gas Company [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
AOCI, beginning balance	(8)	(8)	(9)
OCI before reclassifications	(4)	(1)
Amounts reclassified from AOCI	4	1	1
Total other comprehensive income (loss)	0	0	1
AOCI, ending balance	(10)	(8)	(8)
Cumulative-effect adjustment from change in accounting principle		(2)
Accumulated other comprehensive income (loss) [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
AOCI, beginning balance	(764)	(626)	(748)
OCI before reclassifications	(177)	(156)	103
Amounts reclassified from AOCI	44	21	19
Total other comprehensive income (loss)	(133)	(135)	122
AOCI, ending balance	(939)	(764)	(626)
Cumulative-effect adjustment from change in accounting principle		(42)	(3)	$ (42)	$ (3)
Accumulated other comprehensive income (loss) [Member] | San Diego Gas and Electric Company [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
AOCI, beginning balance	(10)	(8)	(8)
OCI before reclassifications	(5)	(6)	(1)
Amounts reclassified from AOCI	1	4	1
Total other comprehensive income (loss)	(4)	(2)	0
AOCI, ending balance	(16)	(10)	(8)
Cumulative-effect adjustment from change in accounting principle		(2)
Accumulated other comprehensive income (loss) [Member] | Southern California Gas Company [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
AOCI, beginning balance	(20)	(21)	(22)
OCI before reclassifications	(4)	(1)
Amounts reclassified from AOCI	5	2	1
Total other comprehensive income (loss)	1	1	1
AOCI, ending balance	$ (23)	(20)	$ (21)
Cumulative-effect adjustment from change in accounting principle		$ (4)