SIGNIFICANT ACCOUNTING POLICIES AND OTHER FINANCIAL DATA - PROPERTY, PLANT, AND EQUIPMENT (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Property, Plant and Equipment [Line Items]
Property, plant and equipment	$ 49,315	$ 48,108
Depreciation	1,528	1,422	$ 1,236
Accumulated depreciation	12,519	11,605
San Diego Gas and Electric Company [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment	21,662	19,787
Depreciation	686	621	583
Accumulated depreciation	5,352	4,949
Southern California Gas Company [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment	18,138	16,772
Depreciation	553	514	$ 474
Accumulated depreciation	5,699	5,366
Electricity [Member] | San Diego Gas and Electric Company [Member]
Property, Plant and Equipment [Line Items]
Accumulated depreciation	4,558	4,193
Accumulated depreciation of capital leased assets	48	47
Natural gas operations [Member] | San Diego Gas and Electric Company [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment	$ 2,382	$ 2,186
Depreciation rates (percentage)	2.44%	2.40%	2.40%
Accumulated depreciation	$ 794	$ 756
Natural gas operations [Member] | Southern California Gas Company [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment	$ 17,268	$ 15,759
Depreciation rates (percentage)	3.60%	3.63%	3.64%
Capital leased assets	$ 40	$ 34
Accumulated depreciation	5,685	5,352
Accumulated depreciation of capital leased assets	37	33
Electric distribution [Member] | San Diego Gas and Electric Company [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment	$ 7,462	$ 6,975
Depreciation rates (percentage)	3.91%	3.92%	3.86%
Electric transmission [Member] | San Diego Gas and Electric Company [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment	$ 6,222	$ 5,626
Depreciation rates (percentage)	2.76%	2.71%	2.66%
Electric generation [Member] | San Diego Gas and Electric Company [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment	$ 2,967	$ 2,435
Depreciation rates (percentage)	4.12%	4.05%	4.00%
Capital leased assets	$ 1,300	$ 757
Other electric [Member] | San Diego Gas and Electric Company [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment	$ 1,408	$ 1,114
Depreciation rates (percentage)	6.43%	5.54%	5.66%
Capital leased assets	$ 13	$ 22
Other non-utility [Member] | Southern California Gas Company [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment	$ 34	$ 32
Depreciation rates (percentage)	5.39%	5.28%	6.55%
Accumulated depreciation	$ 14	$ 14
Other non-utility [Member] | Other Operating Units and Parent [Member]
Property, Plant and Equipment [Line Items]
Accumulated depreciation	1,125	972
Construction work in progress [Member] | San Diego Gas and Electric Company [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment	1,221	1,451
Construction work in progress [Member] | Southern California Gas Company [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment	836	981
Land and land rights [Member] | Other Operating Units and Parent [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment	$ 429	416
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	30 years
Utility electric distribution operations [Member] | Other Operating Units and Parent [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment	$ 1,977	1,751
Accumulated depreciation	$ 343	318
Utility electric distribution operations [Member] | Minimum [Member] | Other Operating Units and Parent [Member]
Property, Plant and Equipment [Line Items]
Estimated useful life	10 years
Utility electric distribution operations [Member] | Maximum [Member] | Other Operating Units and Parent [Member]
Property, Plant and Equipment [Line Items]
Estimated useful life	45 years
Utility electric distribution operations [Member] | Weighted Average [Member] | Other Operating Units and Parent [Member]
Property, Plant and Equipment [Line Items]
Estimated useful life	41 years
Generating plants [Member] | Other Operating Units and Parent [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment	$ 1,051	2,242
Generating plants [Member] | Minimum [Member] | Other Operating Units and Parent [Member]
Property, Plant and Equipment [Line Items]
Estimated useful life	5 years
Generating plants [Member] | Maximum [Member] | Other Operating Units and Parent [Member]
Property, Plant and Equipment [Line Items]
Estimated useful life	100 years
Generating plants [Member] | Weighted Average [Member] | Other Operating Units and Parent [Member]
Property, Plant and Equipment [Line Items]
Estimated useful life	30 years
LNG terminals [Member] | Other Operating Units and Parent [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment	$ 1,134	1,133
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	$ 3,413	4,408
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	$ 205	269
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	7 years
Construction work in progress [Member] | Other Operating Units and Parent [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment	$ 684	691
Other [Member] | Other Operating Units and Parent [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment	622	639
Capital leased assets	136	136
Leasehold Improvements, Gross	24	24
Accumulated depreciation of capital leased assets	$ 10	7
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	80 years
Other [Member] | Weighted Average [Member] | Other Operating Units and Parent [Member]
Property, Plant and Equipment [Line Items]
Estimated useful life	31 years
Leasehold Improvements [Member] | Other Operating Units and Parent [Member]
Property, Plant and Equipment [Line Items]
Accumulated depreciation	$ 3	2
Plant, pipeline and other distribution assets of ecogas [Member]
Property, Plant and Equipment [Line Items]
Accumulated depreciation	43	39
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	154	145
Total Other Operating Units And Parent [Member] | Other Operating Units and Parent [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment	9,515	11,549
Accumulated depreciation	1,468	$ 1,290
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	$ 457
Ownership interest	92.00%
Accumulated depreciation	$ 252
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	$ 26