FAIR VALUE MEASUREMENTS - FINANCIAL INSTRUMENTS (Details) - USD ($)	Mar. 31, 2019	Dec. 31, 2018
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Unamortized discount (net of premium) and debt issuance costs	$ 201,000,000	$ 206,000,000
Finance Lease, Liability	1,277,000,000
Build-to-suit and capital lease obligations		1,413,000,000
Level 3 [Member] | Otay Mesa VIE [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total long-term debt	220,000,000	220,000,000
Carrying amount [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term amounts due from unconsolidated affiliates	668,000,000	644,000,000
Long-term amounts due to unconsolidated affiliate	38,000,000	37,000,000
Total long-term debt	20,814,000,000	21,340,000,000
Fair value [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term amounts due from unconsolidated affiliates	689,000,000	652,000,000
Long-term amounts due to unconsolidated affiliate	37,000,000	35,000,000
Total long-term debt	20,846,000,000	20,863,000,000
Fair value [Member] | Level 1 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term amounts due from unconsolidated affiliates	0	0
Long-term amounts due to unconsolidated affiliate	0	0
Total long-term debt	0	0
Fair value [Member] | Level 2 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term amounts due from unconsolidated affiliates	689,000,000	648,000,000
Long-term amounts due to unconsolidated affiliate	37,000,000	35,000,000
Total long-term debt	20,598,000,000	20,616,000,000
Fair value [Member] | Level 3 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term amounts due from unconsolidated affiliates	0	4,000,000
Long-term amounts due to unconsolidated affiliate	0	0
Total long-term debt	248,000,000	247,000,000
San Diego Gas and Electric Company [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Unamortized discount (net of premium) and debt issuance costs	48,000,000	49,000,000
Finance Lease, Liability	1,272,000,000
Capital lease obligations		1,272,000,000
San Diego Gas and Electric Company [Member] | Carrying amount [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total long-term debt	4,978,000,000	4,996,000,000
San Diego Gas and Electric Company [Member] | Fair value [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total long-term debt	5,138,000,000	5,117,000,000
San Diego Gas and Electric Company [Member] | Fair value [Member] | Level 1 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total long-term debt	0	0
San Diego Gas and Electric Company [Member] | Fair value [Member] | Level 2 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total long-term debt	4,918,000,000	4,897,000,000
San Diego Gas and Electric Company [Member] | Fair value [Member] | Level 3 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total long-term debt	220,000,000	220,000,000
Southern California Gas Company [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Unamortized discount (net of premium) and debt issuance costs	32,000,000	32,000,000
Finance Lease, Liability	5,000,000
Capital lease obligations		3,000,000
Southern California Gas Company [Member] | Carrying amount [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total long-term debt	3,459,000,000	3,459,000,000
Southern California Gas Company [Member] | Fair value [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total long-term debt	3,595,000,000	3,505,000,000
Southern California Gas Company [Member] | Fair value [Member] | Level 1 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total long-term debt	0	0
Southern California Gas Company [Member] | Fair value [Member] | Level 2 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total long-term debt	3,595,000,000	3,505,000,000
Southern California Gas Company [Member] | Fair value [Member] | Level 3 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total long-term debt	$ 0	$ 0