DERIVATIVE FINANCIAL INSTRUMENTS - DERIVATIVE INSTRUMENTS ON THE CONDENSED BALANCE SHEET (Details) - USD ($) $ in Millions	Sep. 30, 2021	Dec. 31, 2020
Other current assets [Member]
Derivatives not designated as hedging instruments:
Net amounts presented on the balance sheet	$ 73	$ 57
Additional cash collateral for commodity contracts not subject to rate recovery	47	21
Additional cash collateral for commodity contracts subject to rate recovery	30	30
Total	150	108
Other long-term assets [Member]
Derivatives not designated as hedging instruments:
Net amounts presented on the balance sheet	86	100
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	86	100
Other Current Liabilities [Member]
Derivatives not designated as hedging instruments:
Net amounts presented on the balance sheet	(154)	(72)
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	(154)	(72)
Deferred credits and other [Member]
Derivatives not designated as hedging instruments:
Net amounts presented on the balance sheet	(143)	(188)
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	(143)	(188)
Designated as Hedging Instrument [Member] | Other current assets [Member]
Derivatives designated as hedging instruments:
Interest rate and foreign exchange instruments	0	0
Designated as Hedging Instrument [Member] | Other long-term assets [Member]
Derivatives designated as hedging instruments:
Interest rate and foreign exchange instruments	6	1
Designated as Hedging Instrument [Member] | Other Current Liabilities [Member]
Derivatives designated as hedging instruments:
Interest rate and foreign exchange instruments	(42)	(26)
Designated as Hedging Instrument [Member] | Deferred credits and other [Member]
Derivatives designated as hedging instruments:
Interest rate and foreign exchange instruments	(134)	(160)
Not Designated as Hedging Instrument [Member] | Other current assets [Member]
Derivatives not designated as hedging instruments:
Foreign exchange instruments		24
Commodity contracts not subject to rate recovery	252	82
Associated offsetting commodity contracts	(225)	(82)
Associated offsetting cash collateral	0
Commodity contracts subject to rate recovery	50	35
Associated offsetting commodity contracts	(4)	(2)
Not Designated as Hedging Instrument [Member] | Other long-term assets [Member]
Derivatives not designated as hedging instruments:
Foreign exchange instruments		0
Commodity contracts not subject to rate recovery	19	17
Associated offsetting commodity contracts	(15)	(13)
Associated offsetting cash collateral	0
Commodity contracts subject to rate recovery	76	95
Associated offsetting commodity contracts	0	0
Not Designated as Hedging Instrument [Member] | Other Current Liabilities [Member]
Derivatives not designated as hedging instruments:
Foreign exchange instruments		0
Commodity contracts not subject to rate recovery	(300)	(95)
Associated offsetting commodity contracts	225	82
Associated offsetting cash collateral	11
Commodity contracts subject to rate recovery	(52)	(35)
Associated offsetting commodity contracts	4	2
Not Designated as Hedging Instrument [Member] | Deferred credits and other [Member]
Derivatives not designated as hedging instruments:
Foreign exchange instruments		0
Commodity contracts not subject to rate recovery	(21)	(16)
Associated offsetting commodity contracts	15	13
Associated offsetting cash collateral	0
Commodity contracts subject to rate recovery	(3)	(25)
Associated offsetting commodity contracts	0	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	44	31
Additional cash collateral for commodity contracts subject to rate recovery	28	24
Total	72	55
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	76	95
Additional cash collateral for commodity contracts subject to rate recovery	0	0
Total	76	95
San Diego Gas and Electric Company [Member] | Other Current Liabilities [Member]
Derivatives not designated as hedging instruments:
Net amounts presented on the balance sheet	(15)	(27)
Additional cash collateral for commodity contracts subject to rate recovery	0	0
Total	(15)	(27)
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	(2)	(25)
Additional cash collateral for commodity contracts subject to rate recovery	0	0
Total	(2)	(25)
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	47	32
Associated offsetting commodity contracts	(3)	(1)
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	76	95
Associated offsetting commodity contracts	0	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	(18)	(28)
Associated offsetting commodity contracts	3	1
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	(2)	(25)
Associated offsetting commodity contracts	0	0
Southern California Gas Company [Member] | Other current assets [Member]
Derivatives not designated as hedging instruments:
Net amounts presented on the balance sheet	2	2
Additional cash collateral for commodity contracts subject to rate recovery	2	6
Total	4	8
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	(33)	(6)
Additional cash collateral for commodity contracts subject to rate recovery	0	0
Total	(33)	(6)
Southern California Gas Company [Member] | Deferred credits and other [Member]
Derivatives not designated as hedging instruments:
Net amounts presented on the balance sheet	(1)	0
Additional cash collateral for commodity contracts subject to rate recovery	0	0
Total	(1)	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	3
Associated offsetting commodity contracts	(1)	(1)
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	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	(34)	(7)
Associated offsetting commodity contracts	1	1
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	(1)	0
Associated offsetting commodity contracts	$ 0	$ 0