FAIR VALUE MEASUREMENTS - FINANCIAL INSTRUMENTS (Details) - USD ($) $ in Millions		Jun. 30, 2016	Dec. 31, 2015
Carrying Amount
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair value of financial instruments, Total long-term debt	[1],[2]	$ 13,811	$ 13,761
Preferred Stock Of Subsidiaries Fair Value Disclosure		20	20
Due from affiliate, noncurrent, Fair Value Disclosure	[3]	179	175
Accumulated Interest Outstanding		13	11
Unamortized Discount and Debt Issuance Costs		111	107
Build-To-Suit and Capital Lease Obligations		385	387
Carrying Amount | Otay Mesa Energy Center Loan Payable Currently Through April 2019 Member [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Debt Instrument Carrying Amount		310	315
Carrying Amount | San Diego Gas and Electric Company [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair value of financial instruments, Total long-term debt	[2],[4]	4,677	4,304
Capital Lease Obligations		242	244
Unamortized Discount and Debt Issuance Costs		47	43
Carrying Amount | Southern California Gas Company [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair value of financial instruments, Total long-term debt	[5]	3,009	2,513
Preferred Stock Of Subsidiaries Fair Value Disclosure		22	22
Capital Lease Obligations		1	1
Unamortized Discount and Debt Issuance Costs		28	24
Fair Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair value of financial instruments, Total long-term debt	[1],[2]	15,505	14,633
Preferred Stock Of Subsidiaries Fair Value Disclosure		25	23
Due from affiliate, noncurrent, Fair Value Disclosure	[3]	171	166
Fair Value | Fair Value, Inputs, Level 1 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair value of financial instruments, Total long-term debt	[1],[2]	0	0
Preferred Stock Of Subsidiaries Fair Value Disclosure		0	0
Due from affiliate, noncurrent, Fair Value Disclosure	[3]	0	0
Fair Value | Fair Value, Inputs, Level 2 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair value of financial instruments, Total long-term debt	[1],[2]	14,933	13,985
Preferred Stock Of Subsidiaries Fair Value Disclosure		25	23
Due from affiliate, noncurrent, Fair Value Disclosure	[3]	94	97
Fair Value | Fair Value, Inputs, Level 3 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair value of financial instruments, Total long-term debt	[1],[2]	572	648
Preferred Stock Of Subsidiaries Fair Value Disclosure		0	0
Due from affiliate, noncurrent, Fair Value Disclosure	[3]	77	69
Fair Value | San Diego Gas and Electric Company [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair value of financial instruments, Total long-term debt	[2],[4]	5,365	4,670
Fair Value | San Diego Gas and Electric Company [Member] | Fair Value, Inputs, Level 1 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair value of financial instruments, Total long-term debt	[2],[4]	0	0
Fair Value | San Diego Gas and Electric Company [Member] | Fair Value, Inputs, Level 2 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair value of financial instruments, Total long-term debt	[2],[4]	5,055	4,355
Fair Value | San Diego Gas and Electric Company [Member] | Fair Value, Inputs, Level 3 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair value of financial instruments, Total long-term debt	[2],[4]	310	315
Fair Value | Southern California Gas Company [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair value of financial instruments, Total long-term debt	[5]	3,335	2,621
Preferred Stock Of Subsidiaries Fair Value Disclosure		27	25
Fair Value | Southern California Gas Company [Member] | Fair Value, Inputs, Level 1 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair value of financial instruments, Total long-term debt	[5]	0	0
Preferred Stock Of Subsidiaries Fair Value Disclosure		0	0
Fair Value | Southern California Gas Company [Member] | Fair Value, Inputs, Level 2 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair value of financial instruments, Total long-term debt	[5]	3,335	2,621
Preferred Stock Of Subsidiaries Fair Value Disclosure		27	25
Fair Value | Southern California Gas Company [Member] | Fair Value, Inputs, Level 3 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair value of financial instruments, Total long-term debt	[5]	0	0
Preferred Stock Of Subsidiaries Fair Value Disclosure		$ 0	$ 0

[1] Before reductions for unamortized discount (net of premium) and debt issuance costs of $111 million and $107 million at June 30, 2016 and December 31, 2015, respectively, and excluding build-to-suit and capital lease obligations of $385 million and $387 million at June 30, 2016 and December 31, 2015, respectively. We discuss our long-term debt in Note 6 above and in Note 5 of the Notes to Consolidated Financial Statements in the Annual Report.

[2] Level 3 instruments include $310 million and $315 million at June 30, 2016 and December 31, 2015, respectively, related to Otay Mesa VIE.

[3] Excluding accumulated interest outstanding of $13 million and $11 million at June 30, 2016 and December 31, 2015, respectively.

[4] Before reductions for unamortized discount and debt issuance costs of $47 million and $43 million at June 30, 2016 and December 31, 2015, respectively, and excluding capital lease obligations of $242 million and $244 million at June 30, 2016 and December 31, 2015, respectively.

[5] Before reductions for unamortized discount and debt issuance costs of $28 million and $24 million at June 30, 2016 and December 31, 2015, respectively, and excluding capital lease obligations of $1 million both at June 30, 2016 and December 31, 2015.