DERIVATIVE FINANCIAL INSTRUMENTS - DERIVATIVE INSTRUMENTS ON THE CONDENSED BALANCE SHEET (Details) - USD ($) $ in Millions	Mar. 31, 2021	Dec. 31, 2020
Other current assets [Member]
Derivatives not designated as hedging instruments:
Net amounts presented on the balance sheet	$ 35	$ 57
Additional cash collateral for commodity contracts not subject to rate recovery	24	21
Additional cash collateral for commodity contracts subject to rate recovery	27	30
Total	86	108
Other long-term assets [Member]
Derivatives not designated as hedging instruments:
Net amounts presented on the balance sheet	100	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	100	100
Other Current Liabilities [Member]
Derivatives not designated as hedging instruments:
Net amounts presented on the balance sheet	(71)	(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	(71)	(72)
Deferred credits and other [Member]
Derivatives not designated as hedging instruments:
Net amounts presented on the balance sheet	(192)	(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	(192)	(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	8	1
Designated as Hedging Instrument [Member] | Other Current Liabilities [Member]
Derivatives designated as hedging instruments:
Interest rate and foreign exchange instruments	(22)	(26)
Designated as Hedging Instrument [Member] | Deferred credits and other [Member]
Derivatives designated as hedging instruments:
Interest rate and foreign exchange instruments	(161)	(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	57	82
Associated offsetting commodity contracts	(53)	(82)
Commodity contracts subject to rate recovery	31	35
Associated offsetting commodity contracts		(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	15	17
Associated offsetting commodity contracts	(15)	(13)
Commodity contracts subject to rate recovery	92	95
Associated offsetting commodity contracts		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	(73)	(95)
Associated offsetting commodity contracts	53	82
Commodity contracts subject to rate recovery	(29)	(35)
Associated offsetting commodity contracts		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	(20)	(16)
Associated offsetting commodity contracts	15	13
Commodity contracts subject to rate recovery	(26)	(25)
Associated offsetting commodity contracts		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	27	31
Additional cash collateral for commodity contracts subject to rate recovery	26	24
Total	53	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	92	95
Additional cash collateral for commodity contracts subject to rate recovery	0	0
Total	92	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	(25)	(27)
Additional cash collateral for commodity contracts subject to rate recovery	0	0
Total	(25)	(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	(25)	(25)
Additional cash collateral for commodity contracts subject to rate recovery	0	0
Total	(25)	(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	27	32
Associated offsetting commodity contracts		(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	92	95
Associated offsetting commodity contracts		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	(25)	(28)
Associated offsetting commodity contracts		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	(25)	(25)
Associated offsetting commodity contracts		0
Southern California Gas Company [Member] | Other current assets [Member]
Derivatives not designated as hedging instruments:
Net amounts presented on the balance sheet	4	2
Additional cash collateral for commodity contracts subject to rate recovery	1	6
Total	5	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	(4)	(6)
Additional cash collateral for commodity contracts subject to rate recovery	0	0
Total	(4)	(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	4	3
Associated offsetting commodity contracts		(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
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	(4)	(7)
Associated offsetting commodity contracts		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