DERIVATIVE FINANCIAL INSTRUMENTS - DERIVATIVE INSTRUMENTS ON THE CONDENSED BALANCE SHEET (Details) - USD ($) $ in Millions	Sep. 30, 2020	Dec. 31, 2019
Other current assets [Member]
Derivatives not designated as hedging instruments:
Net amounts presented on the balance sheet	$ 23	$ 58
Additional cash collateral for commodity contracts not subject to rate recovery	41	43
Additional cash collateral for commodity contracts subject to rate recovery	24	25
Total	88	126
Other long-term assets [Member]
Derivatives not designated as hedging instruments:
Net amounts presented on the balance sheet	89	85
Additional cash collateral for commodity contracts not subject to rate recovery	0	0
Additional cash collateral for commodity contracts subject to rate recovery	0	0
Total	89	85
Other Current Liabilities [Member]
Derivatives not designated as hedging instruments:
Net amounts presented on the balance sheet	(75)	(53)
Additional cash collateral for commodity contracts not subject to rate recovery	0	0
Additional cash collateral for commodity contracts subject to rate recovery	0	0
Total	(75)	(53)
Deferred credits and other [Member]
Derivatives not designated as hedging instruments:
Net amounts presented on the balance sheet	(220)	(192)
Additional cash collateral for commodity contracts not subject to rate recovery	0	0
Additional cash collateral for commodity contracts subject to rate recovery	0	0
Total	(220)	(192)
Designated as Hedging Instrument [Member] | Other current assets [Member]
Derivatives designated as hedging instruments:
Interest rate and foreign exchange instruments	6	0
Designated as Hedging Instrument [Member] | Other long-term assets [Member]
Derivatives designated as hedging instruments:
Interest rate and foreign exchange instruments	2	3
Designated as Hedging Instrument [Member] | Other Current Liabilities [Member]
Derivatives designated as hedging instruments:
Interest rate and foreign exchange instruments	(22)	(17)
Designated as Hedging Instrument [Member] | Deferred credits and other [Member]
Derivatives designated as hedging instruments:
Interest rate and foreign exchange instruments	(188)	(140)
Not Designated as Hedging Instrument [Member] | Other current assets [Member]
Derivatives not designated as hedging instruments:
Foreign exchange instruments	13	41
Associated offsetting foreign exchange instruments	(13)	(20)
Commodity contracts not subject to rate recovery	102	34
Associated offsetting commodity contracts	(100)	(32)
Commodity contracts subject to rate recovery	17	41
Associated offsetting commodity contracts	(2)	(6)
Associated offsetting cash collateral		0
Not Designated as Hedging Instrument [Member] | Other long-term assets [Member]
Derivatives not designated as hedging instruments:
Foreign exchange instruments	0	0
Associated offsetting foreign exchange instruments	0	0
Commodity contracts not subject to rate recovery	7	11
Associated offsetting commodity contracts	(4)	(2)
Commodity contracts subject to rate recovery	84	76
Associated offsetting commodity contracts	0	(3)
Associated offsetting cash collateral		0
Not Designated as Hedging Instrument [Member] | Other Current Liabilities [Member]
Derivatives not designated as hedging instruments:
Foreign exchange instruments	(22)	(20)
Associated offsetting foreign exchange instruments	13	20
Commodity contracts not subject to rate recovery	(114)	(41)
Associated offsetting commodity contracts	100	32
Commodity contracts subject to rate recovery	(32)	(47)
Associated offsetting commodity contracts	2	6
Associated offsetting cash collateral		14
Not Designated as Hedging Instrument [Member] | Deferred credits and other [Member]
Derivatives not designated as hedging instruments:
Foreign exchange instruments	0	0
Associated offsetting foreign exchange instruments	0	0
Commodity contracts not subject to rate recovery	(7)	(10)
Associated offsetting commodity contracts	4	2
Commodity contracts subject to rate recovery	(29)	(47)
Associated offsetting commodity contracts	0	3
Associated offsetting cash collateral		0
San Diego Gas and Electric Company [Member] | Other current assets [Member]
Derivatives not designated as hedging instruments:
Net amounts presented on the balance sheet	12	26
Additional cash collateral for commodity contracts subject to rate recovery	22	16
Total	34	42
San Diego Gas and Electric Company [Member] | Other long-term assets [Member]
Derivatives not designated as hedging instruments:
Net amounts presented on the balance sheet	84	73
Additional cash collateral for commodity contracts subject to rate recovery	0	0
Total	84	73
San Diego Gas and Electric Company [Member] | Other Current Liabilities [Member]
Derivatives not designated as hedging instruments:
Net amounts presented on the balance sheet	(24)	(23)
Additional cash collateral for commodity contracts subject to rate recovery	0	0
Total	(24)	(23)
San Diego Gas and Electric Company [Member] | Deferred credits and other [Member]
Derivatives not designated as hedging instruments:
Net amounts presented on the balance sheet	(29)	(44)
Additional cash collateral for commodity contracts subject to rate recovery	0	0
Total	(29)	(44)
San Diego Gas and Electric Company [Member] | Not Designated as Hedging Instrument [Member] | Other current assets [Member]
Derivatives not designated as hedging instruments:
Commodity contracts subject to rate recovery	14	30
Associated offsetting commodity contracts	(2)	(4)
Associated offsetting cash collateral		0
San Diego Gas and Electric Company [Member] | Not Designated as Hedging Instrument [Member] | Other long-term assets [Member]
Derivatives not designated as hedging instruments:
Commodity contracts subject to rate recovery	84	76
Associated offsetting commodity contracts	0	(3)
Associated offsetting cash collateral		0
San Diego Gas and Electric Company [Member] | Not Designated as Hedging Instrument [Member] | Other Current Liabilities [Member]
Derivatives not designated as hedging instruments:
Commodity contracts subject to rate recovery	(26)	(41)
Associated offsetting commodity contracts	2	4
Associated offsetting cash collateral		14
San Diego Gas and Electric Company [Member] | Not Designated as Hedging Instrument [Member] | Deferred credits and other [Member]
Derivatives not designated as hedging instruments:
Commodity contracts subject to rate recovery	(29)	(47)
Associated offsetting commodity contracts	0	3
Associated offsetting cash collateral		0
Southern California Gas Company [Member] | Other current assets [Member]
Derivatives not designated as hedging instruments:
Net amounts presented on the balance sheet	3	9
Additional cash collateral for commodity contracts subject to rate recovery	2	9
Total	5	18
Southern California Gas Company [Member] | Other long-term assets [Member]
Derivatives not designated as hedging instruments:
Net amounts presented on the balance sheet	0	0
Additional cash collateral for commodity contracts subject to rate recovery	0	0
Total	0	0
Southern California Gas Company [Member] | Other Current Liabilities [Member]
Derivatives not designated as hedging instruments:
Net amounts presented on the balance sheet	(6)	(4)
Additional cash collateral for commodity contracts subject to rate recovery	0	0
Total	(6)	(4)
Southern California Gas Company [Member] | Deferred credits and other [Member]
Derivatives not designated as hedging instruments:
Net amounts presented on the balance sheet	0	0
Additional cash collateral for commodity contracts subject to rate recovery	0	0
Total	0	0
Southern California Gas Company [Member] | Not Designated as Hedging Instrument [Member] | Other current assets [Member]
Derivatives not designated as hedging instruments:
Commodity contracts subject to rate recovery	3	11
Associated offsetting commodity contracts		(2)
Southern California Gas Company [Member] | Not Designated as Hedging Instrument [Member] | Other long-term assets [Member]
Derivatives not designated as hedging instruments:
Commodity contracts subject to rate recovery	0	0
Associated offsetting commodity contracts		0
Southern California Gas Company [Member] | Not Designated as Hedging Instrument [Member] | Other Current Liabilities [Member]
Derivatives not designated as hedging instruments:
Commodity contracts subject to rate recovery	(6)	(6)
Associated offsetting commodity contracts		2
Southern California Gas Company [Member] | Not Designated as Hedging Instrument [Member] | Deferred credits and other [Member]
Derivatives not designated as hedging instruments:
Commodity contracts subject to rate recovery	$ 0	0
Associated offsetting commodity contracts		$ 0