FAIR VALUE MEASUREMENTS - FINANCIAL INSTRUMENTS (Details) - USD ($) $ in Millions	Sep. 30, 2019	Dec. 31, 2018
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Unamortized discount (net of premium) and debt issuance costs	$ 221	$ 206
Finance lease obligations	1,285
Build-to-suit and capital lease obligations		1,413
Level 3 [Member] \| Otay Mesa VIE [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total long-term debt		220
Carrying amount [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term amounts due from unconsolidated affiliates	712	644
Long-term amounts due to unconsolidated affiliate	39	37
Total long-term debt	21,554	21,340
Fair value [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term amounts due from unconsolidated affiliates	735	652
Long-term amounts due to unconsolidated affiliate	38	35
Total long-term debt	23,168	20,863
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	735	648
Long-term amounts due to unconsolidated affiliate	38	35
Total long-term debt	23,142	20,616
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
Long-term amounts due to unconsolidated affiliate	0	0
Total long-term debt	26	247
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	49	49
Finance lease obligations	1,270
Capital lease obligations		1,272
San Diego Gas and Electric Company [Member] \| Carrying amount [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total long-term debt	5,141	4,996
San Diego Gas and Electric Company [Member] \| Fair value [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total long-term debt	5,780	5,117
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	5,780	4,897
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	0	220
Southern California Gas Company [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Unamortized discount (net of premium) and debt issuance costs	35	32
Finance lease obligations	15
Capital lease obligations		3
Southern California Gas Company [Member] \| Carrying amount [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total long-term debt	3,809	3,459
Southern California Gas Company [Member] \| Fair value [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total long-term debt	4,290	3,505
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	4,290	3,505
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

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Capital Lease Obligations and Build-To-Suit

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Amount equal to the present value (the principal) at the beginning of the lease term of minimum lease payments during the lease term (excluding that portion of the payments representing executory costs such as insurance, maintenance, and taxes to be paid by the lessor, together with any profit thereon) net of payments or other amounts applied to the principal through the balance sheet date.

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Present value of lessee's discounted obligation for lease payments from finance lease.

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