DERIVATIVE FINANCIAL INSTRUMENTS - DERIVATIVE INSTRUMENTS ON THE CONDENSED BALANCE SHEET (Details) - USD ($) $ in Millions	Sep. 30, 2019	Dec. 31, 2018
Current assets: Other [Member]
Derivatives not designated as hedging instruments:
Net amounts presented on the balance sheet	$ 28	$ 80
Additional cash collateral for commodity contracts not subject to rate recovery	18	19
Additional cash collateral for commodity contracts subject to rate recovery	17	33
Total	63	132
Other assets: Sundry [Member]
Derivatives not designated as hedging instruments:
Net amounts presented on the balance sheet	253	235
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	253	235
Current liabilities: Other [Member]
Derivatives not designated as hedging instruments:
Net amounts presented on the balance sheet	(52)	(70)
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	(52)	(70)
Deferred credits and other liabilities: Deferred credits and other [Member]
Derivatives not designated as hedging instruments:
Net amounts presented on the balance sheet	(214)	(218)
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	(214)	(218)
Designated as Hedging Instrument [Member] | Current assets: Other [Member]
Derivatives designated as hedging instruments:
Interest rate and foreign exchange instruments	0	2
Designated as Hedging Instrument [Member] | Other assets: Sundry [Member]
Derivatives designated as hedging instruments:
Interest rate and foreign exchange instruments	0	0
Designated as Hedging Instrument [Member] | Current liabilities: Other [Member]
Derivatives designated as hedging instruments:
Interest rate and foreign exchange instruments	(12)	(3)
Designated as Hedging Instrument [Member] | Deferred credits and other liabilities: Deferred credits and other [Member]
Derivatives designated as hedging instruments:
Interest rate and foreign exchange instruments	(157)	(147)
Not Designated as Hedging Instrument [Member] | Current assets: Other [Member]
Derivatives not designated as hedging instruments:
Foreign exchange instruments	12
Associated offsetting foreign exchange instruments	(3)
Commodity contracts not subject to rate recovery	31	153
Associated offsetting commodity contracts	(29)	(133)
Commodity contracts subject to rate recovery	22	64
Associated offsetting commodity contracts	(5)	(6)
Associated offsetting cash collateral	0	0
Not Designated as Hedging Instrument [Member] | Other assets: Sundry [Member]
Derivatives not designated as hedging instruments:
Foreign exchange instruments	0
Associated offsetting foreign exchange instruments	0
Commodity contracts not subject to rate recovery	11	7
Associated offsetting commodity contracts	(1)	(3)
Commodity contracts subject to rate recovery	245	233
Associated offsetting commodity contracts	(2)	(2)
Associated offsetting cash collateral	0	0
Not Designated as Hedging Instrument [Member] | Current liabilities: Other [Member]
Derivatives not designated as hedging instruments:
Foreign exchange instruments	(3)
Associated offsetting foreign exchange instruments	3
Commodity contracts not subject to rate recovery	(39)	(164)
Associated offsetting commodity contracts	29	133
Commodity contracts subject to rate recovery	(48)	(42)
Associated offsetting commodity contracts	5	6
Associated offsetting cash collateral	13	0
Not Designated as Hedging Instrument [Member] | Deferred credits and other liabilities: Deferred credits and other [Member]
Derivatives not designated as hedging instruments:
Foreign exchange instruments	0
Associated offsetting foreign exchange instruments	0
Commodity contracts not subject to rate recovery	(9)	(6)
Associated offsetting commodity contracts	1	3
Commodity contracts subject to rate recovery	(53)	(72)
Associated offsetting commodity contracts	2	2
Associated offsetting cash collateral	2	2
San Diego Gas and Electric Company [Member] | Current assets: Other [Member]
Derivatives not designated as hedging instruments:
Net amounts presented on the balance sheet	11	54
Additional cash collateral for commodity contracts subject to rate recovery	14	28
Total	25	82
San Diego Gas and Electric Company [Member] | Other assets: Sundry [Member]
Derivatives not designated as hedging instruments:
Net amounts presented on the balance sheet	243	231
Additional cash collateral for commodity contracts subject to rate recovery	0	0
Total	243	231
San Diego Gas and Electric Company [Member] | Current liabilities: Other [Member]
Derivatives not designated as hedging instruments:
Net amounts presented on the balance sheet	(26)	(32)
Additional cash collateral for commodity contracts subject to rate recovery	0	0
Total	(26)	(32)
San Diego Gas and Electric Company [Member] | Deferred credits and other liabilities: Deferred credits and other [Member]
Derivatives not designated as hedging instruments:
Net amounts presented on the balance sheet	(49)	(68)
Additional cash collateral for commodity contracts subject to rate recovery	0	0
Total	(49)	(68)
San Diego Gas and Electric Company [Member] | Designated as Hedging Instrument [Member] | Current assets: Other [Member]
Derivatives designated as hedging instruments:
Interest rate instruments		0
San Diego Gas and Electric Company [Member] | Designated as Hedging Instrument [Member] | Other assets: Sundry [Member]
Derivatives designated as hedging instruments:
Interest rate instruments		0
San Diego Gas and Electric Company [Member] | Designated as Hedging Instrument [Member] | Current liabilities: Other [Member]
Derivatives designated as hedging instruments:
Interest rate instruments		(1)
San Diego Gas and Electric Company [Member] | Designated as Hedging Instrument [Member] | Deferred credits and other liabilities: Deferred credits and other [Member]
Derivatives designated as hedging instruments:
Interest rate instruments		0
San Diego Gas and Electric Company [Member] | Not Designated as Hedging Instrument [Member] | Current assets: Other [Member]
Derivatives not designated as hedging instruments:
Commodity contracts subject to rate recovery	14	60
Associated offsetting commodity contracts	(3)	(6)
Associated offsetting cash collateral	0	0
San Diego Gas and Electric Company [Member] | Not Designated as Hedging Instrument [Member] | Other assets: Sundry [Member]
Derivatives not designated as hedging instruments:
Commodity contracts subject to rate recovery	245	233
Associated offsetting commodity contracts	(2)	(2)
Associated offsetting cash collateral	0	0
San Diego Gas and Electric Company [Member] | Not Designated as Hedging Instrument [Member] | Current liabilities: Other [Member]
Derivatives not designated as hedging instruments:
Commodity contracts subject to rate recovery	(42)	(37)
Associated offsetting commodity contracts	3	6
Associated offsetting cash collateral	13	0
San Diego Gas and Electric Company [Member] | Not Designated as Hedging Instrument [Member] | Deferred credits and other liabilities: Deferred credits and other [Member]
Derivatives not designated as hedging instruments:
Commodity contracts subject to rate recovery	(53)	(72)
Associated offsetting commodity contracts	2	2
Associated offsetting cash collateral	2	2
Southern California Gas Company [Member] | Current assets: Other [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	3	5
Total	9	9
Southern California Gas Company [Member] | Other assets: Sundry [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] | Current liabilities: Other [Member]
Derivatives not designated as hedging instruments:
Net amounts presented on the balance sheet	(4)	(5)
Additional cash collateral for commodity contracts subject to rate recovery	0	0
Total	(4)	(5)
Southern California Gas Company [Member] | Deferred credits and other liabilities: 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] | Current assets: Other [Member]
Derivatives not designated as hedging instruments:
Commodity contracts subject to rate recovery	8	4
Associated offsetting commodity contracts	(2)
Southern California Gas Company [Member] | Not Designated as Hedging Instrument [Member] | Other assets: Sundry [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] | Current liabilities: Other [Member]
Derivatives not designated as hedging instruments:
Commodity contracts subject to rate recovery	(6)	(5)
Associated offsetting commodity contracts	2
Southern California Gas Company [Member] | Not Designated as Hedging Instrument [Member] | Deferred credits and other liabilities: Deferred credits and other [Member]
Derivatives not designated as hedging instruments:
Commodity contracts subject to rate recovery	0	$ 0
Associated offsetting commodity contracts	$ 0