SIGNIFICANT ACCOUNTING POLICIES AND OTHER FINANCIAL DATA - PROPERTY, PLANT, AND EQUIPMENT (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Property, Plant and Equipment [Line Items]
Property, plant and equipment	$ 49,329	$ 46,615
Depreciation expense	1,551	1,470	$ 1,368
Accumulated depreciation	12,877	12,176
San Diego Gas and Electric Company [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment	22,504	21,662
Depreciation expense	757	686	621
Accumulated depreciation	5,537	5,352
Southern California Gas Company [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment	19,362	18,138
Depreciation expense	598	553	$ 514
Accumulated depreciation	6,038	5,699
Natural gas operations [Member] | San Diego Gas and Electric Company [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment	$ 2,534	$ 2,382
Depreciation rates (percentage)	2.47%	2.44%	2.40%
Accumulated depreciation	$ 832	$ 794
Natural gas operations [Member] | Southern California Gas Company [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment	$ 18,370	$ 17,268
Depreciation rates (percentage)	3.60%	3.60%	3.63%
Capital leased assets		$ 40
Accumulated depreciation	$ 6,023	5,685
Accumulated depreciation of capital leased assets		37
Electric distribution [Member] | San Diego Gas and Electric Company [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment	$ 7,985	$ 7,462
Depreciation rates (percentage)	3.94%	3.91%	3.92%
Electric transmission [Member] | San Diego Gas and Electric Company [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment	$ 6,577	$ 6,222
Depreciation rates (percentage)	2.79%	2.76%	2.71%
Electric generation [Member] | San Diego Gas and Electric Company [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment	$ 2,415	$ 2,967
Depreciation rates (percentage)	4.50%	4.12%	4.05%
Capital leased assets		$ 1,300
Other electric [Member] | San Diego Gas and Electric Company [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment	$ 1,492	$ 1,408
Depreciation rates (percentage)	6.61%	6.43%	5.54%
Capital leased assets		$ 13
Construction work in progress [Member] | San Diego Gas and Electric Company [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment	$ 1,501	1,221
Construction work in progress [Member] | Southern California Gas Company [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment	958	836
Other non-utility [Member] | Southern California Gas Company [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment	$ 34	$ 34
Depreciation rates (percentage)	5.08%	5.39%	5.28%
Accumulated depreciation	$ 15	$ 14
Other non-utility [Member] | Other Operating Units and Parent [Member]
Property, Plant and Equipment [Line Items]
Accumulated depreciation	1,302	1,125
Land and land rights [Member] | Other Operating Units and Parent [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment	$ 278	326
Land and land rights [Member] | Minimum [Member] | Other Operating Units and Parent [Member]
Property, Plant and Equipment [Line Items]
Estimated useful life	16 years
Land and land rights [Member] | Maximum [Member] | Other Operating Units and Parent [Member]
Property, Plant and Equipment [Line Items]
Estimated useful life	50 years
Land and land rights [Member] | Weighted Average [Member] | Other Operating Units and Parent [Member]
Property, Plant and Equipment [Line Items]
Estimated useful life	31 years
Generating plants [Member] | Other Operating Units and Parent [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment	$ 1,154	869
Generating plants [Member] | Minimum [Member] | Other Operating Units and Parent [Member]
Property, Plant and Equipment [Line Items]
Estimated useful life	15 years
Generating plants [Member] | Maximum [Member] | Other Operating Units and Parent [Member]
Property, Plant and Equipment [Line Items]
Estimated useful life	20 years
Generating plants [Member] | Weighted Average [Member] | Other Operating Units and Parent [Member]
Property, Plant and Equipment [Line Items]
Estimated useful life	18 years
LNG terminals [Member] | Other Operating Units and Parent [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment	$ 1,134	1,134
LNG terminals [Member] | Minimum [Member] | Other Operating Units and Parent [Member]
Property, Plant and Equipment [Line Items]
Estimated useful life	43 years
LNG terminals [Member] | Maximum [Member] | Other Operating Units and Parent [Member]
Property, Plant and Equipment [Line Items]
Estimated useful life	43 years
LNG terminals [Member] | Weighted Average [Member] | Other Operating Units and Parent [Member]
Property, Plant and Equipment [Line Items]
Estimated useful life	43 years
Pipelines and storage [Member] | Other Operating Units and Parent [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment	$ 3,596	3,413
Pipelines and storage [Member] | Minimum [Member] | Other Operating Units and Parent [Member]
Property, Plant and Equipment [Line Items]
Estimated useful life	5 years
Pipelines and storage [Member] | Maximum [Member] | Other Operating Units and Parent [Member]
Property, Plant and Equipment [Line Items]
Estimated useful life	50 years
Pipelines and storage [Member] | Weighted Average [Member] | Other Operating Units and Parent [Member]
Property, Plant and Equipment [Line Items]
Estimated useful life	41 years
Other [Member] | Other Operating Units and Parent [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment	$ 180	183
Other [Member] | Minimum [Member] | Other Operating Units and Parent [Member]
Property, Plant and Equipment [Line Items]
Estimated useful life	1 year
Other [Member] | Maximum [Member] | Other Operating Units and Parent [Member]
Property, Plant and Equipment [Line Items]
Estimated useful life	50 years
Other [Member] | Weighted Average [Member] | Other Operating Units and Parent [Member]
Property, Plant and Equipment [Line Items]
Estimated useful life	6 years
Construction work in progress [Member] | Other Operating Units and Parent [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment	$ 895	451
Other [Member] | Other Operating Units and Parent [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment	$ 226	439
Capital leased assets		136
Leasehold Improvements, Gross		24
Accumulated depreciation of capital leased assets		10
Other [Member] | Minimum [Member] | Other Operating Units and Parent [Member]
Property, Plant and Equipment [Line Items]
Estimated useful life	3 years
Other [Member] | Maximum [Member] | Other Operating Units and Parent [Member]
Property, Plant and Equipment [Line Items]
Estimated useful life	50 years
Other [Member] | Weighted Average [Member] | Other Operating Units and Parent [Member]
Property, Plant and Equipment [Line Items]
Estimated useful life	15 years
Total Other Operating Units And Parent [Member] | Other Operating Units and Parent [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment	$ 7,463	6,815
Plant, pipeline and other distribution assets of ecogas [Member]
Property, Plant and Equipment [Line Items]
Accumulated depreciation	49	43
Plant, pipeline and other distribution assets of ecogas [Member] | Other Operating Units and Parent [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment	178	154
Electricity [Member] | San Diego Gas and Electric Company [Member]
Property, Plant and Equipment [Line Items]
Accumulated depreciation	4,705	4,558
Accumulated depreciation of capital leased assets		48
Leasehold Improvements [Member] | Other Operating Units and Parent [Member]
Property, Plant and Equipment [Line Items]
Accumulated depreciation		$ 3
Southwest Powerlink (SWPL) transmission line [Member] | Electric transmission [Member] | San Diego Gas and Electric Company [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment	484
Accumulated depreciation	263
Southwest Powerlink (SWPL) transmission line [Member] | Construction work in progress [Member] | San Diego Gas and Electric Company [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment	$ 13
Southwest Powerlink [Member] | Southwest Powerlink (SWPL) transmission line [Member] | Electric transmission [Member] | San Diego Gas and Electric Company [Member]
Property, Plant and Equipment [Line Items]
Ownership interest	90.00%