DERIVATIVE FINANCIAL INSTRUMENTS - DERIVATIVE INSTRUMENTS ON THE CONDENSED BALANCE SHEET (Details) - USD ($) $ in Millions	Sep. 30, 2018	Dec. 31, 2017
Current assets: Fixed-price contracts and other derivatives [Member]
Derivatives not designated as hedging instruments:
Net amounts presented on the balance sheet	$ 57	$ 47
Additional cash collateral for commodity contracts not subject to rate recovery	11	2
Additional cash collateral for commodity contracts subject to rate recovery	29	17
Total	97	66
Other assets: Sundry [Member]
Derivatives not designated as hedging instruments:
Net amounts presented on the balance sheet	105	105
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	105	105
Current liabilities: Fixed-price contracts and other derivatives [Member]
Derivatives not designated as hedging instruments:
Net amounts presented on the balance sheet	(57)	(103)
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	(57)	(103)
Deferred credits and other liabilities: Fixed-price contracts and other derivatives [Member]
Derivatives not designated as hedging instruments:
Net amounts presented on the balance sheet	(205)	(281)
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	(205)	(281)
Designated as Hedging Instrument [Member] | Current assets: Fixed-price contracts and other derivatives [Member]
Derivatives designated as hedging instruments:
Interest rate and foreign exchange instruments	1	5
Designated as Hedging Instrument [Member] | Other assets: Sundry [Member]
Derivatives designated as hedging instruments:
Interest rate and foreign exchange instruments	6	2
Designated as Hedging Instrument [Member] | Current liabilities: Fixed-price contracts and other derivatives [Member]
Derivatives designated as hedging instruments:
Interest rate and foreign exchange instruments	(7)	(51)
Designated as Hedging Instrument [Member] | Deferred credits and other liabilities: Fixed-price contracts and other derivatives [Member]
Derivatives designated as hedging instruments:
Interest rate and foreign exchange instruments	(125)	(165)
Not Designated as Hedging Instrument [Member] | Current assets: Fixed-price contracts and other derivatives [Member]
Derivatives not designated as hedging instruments:
Foreign exchange instruments	38	0
Commodity contracts not subject to rate recovery	93	81
Associated offsetting commodity contracts	(86)	(67)
Commodity contracts subject to rate recovery	17	28
Associated offsetting commodity contracts	(6)	0
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	0
Commodity contracts not subject to rate recovery	10	8
Associated offsetting commodity contracts	(6)	(5)
Commodity contracts subject to rate recovery	98	101
Associated offsetting commodity contracts	(3)	(1)
Associated offsetting cash collateral	0	0
Not Designated as Hedging Instrument [Member] | Current liabilities: Fixed-price contracts and other derivatives [Member]
Derivatives not designated as hedging instruments:
Foreign exchange instruments	0	(1)
Commodity contracts not subject to rate recovery	(95)	(72)
Associated offsetting commodity contracts	86	67
Commodity contracts subject to rate recovery	(49)	(65)
Associated offsetting commodity contracts	6	0
Associated offsetting cash collateral	2	19
Not Designated as Hedging Instrument [Member] | Deferred credits and other liabilities: Fixed-price contracts and other derivatives [Member]
Derivatives not designated as hedging instruments:
Foreign exchange instruments	0	0
Commodity contracts not subject to rate recovery	(9)	(6)
Associated offsetting commodity contracts	6	5
Commodity contracts subject to rate recovery	(81)	(120)
Associated offsetting commodity contracts	3	1
Associated offsetting cash collateral	1	4
San Diego Gas and Electric Company [Member] | Current assets: Fixed-price contracts and other derivatives [Member]
Derivatives not designated as hedging instruments:
Net amounts presented on the balance sheet	8	26
Additional cash collateral for commodity contracts subject to rate recovery	26	16
Total	34	42
San Diego Gas and Electric Company [Member] | Other assets: Sundry [Member]
Derivatives not designated as hedging instruments:
Net amounts presented on the balance sheet	95	100
Additional cash collateral for commodity contracts subject to rate recovery	0	0
Total	95	100
San Diego Gas and Electric Company [Member] | Current liabilities: Fixed-price contracts and other derivatives [Member]
Derivatives not designated as hedging instruments:
Net amounts presented on the balance sheet	(40)	(54)
Additional cash collateral for commodity contracts subject to rate recovery	0	0
Total	(40)	(54)
San Diego Gas and Electric Company [Member] | Deferred credits and other liabilities: Fixed-price contracts and other derivatives [Member]
Derivatives not designated as hedging instruments:
Net amounts presented on the balance sheet	(77)	(118)
Additional cash collateral for commodity contracts subject to rate recovery	0	0
Total	(77)	(118)
San Diego Gas and Electric Company [Member] | Designated as Hedging Instrument [Member] | Current assets: Fixed-price contracts and other derivatives [Member]
Derivatives designated as hedging instruments:
Interest rate instruments	0	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	0
San Diego Gas and Electric Company [Member] | Designated as Hedging Instrument [Member] | Current liabilities: Fixed-price contracts and other derivatives [Member]
Derivatives designated as hedging instruments:
Interest rate instruments	(4)	(10)
San Diego Gas and Electric Company [Member] | Designated as Hedging Instrument [Member] | Deferred credits and other liabilities: Fixed-price contracts and other derivatives [Member]
Derivatives designated as hedging instruments:
Interest rate instruments	0	(3)
San Diego Gas and Electric Company [Member] | Not Designated as Hedging Instrument [Member] | Current assets: Fixed-price contracts and other derivatives [Member]
Derivatives not designated as hedging instruments:
Commodity contracts subject to rate recovery	14	26
Associated offsetting commodity contracts	(6)	0
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	98	101
Associated offsetting commodity contracts	(3)	(1)
Associated offsetting cash collateral	0	0
San Diego Gas and Electric Company [Member] | Not Designated as Hedging Instrument [Member] | Current liabilities: Fixed-price contracts and other derivatives [Member]
Derivatives not designated as hedging instruments:
Commodity contracts subject to rate recovery	(44)	(63)
Associated offsetting commodity contracts	6	0
Associated offsetting cash collateral	2	19
San Diego Gas and Electric Company [Member] | Not Designated as Hedging Instrument [Member] | Deferred credits and other liabilities: Fixed-price contracts and other derivatives [Member]
Derivatives not designated as hedging instruments:
Commodity contracts subject to rate recovery	(81)	(120)
Associated offsetting commodity contracts	3	1
Associated offsetting cash collateral	1	4
Southern California Gas Company [Member] | Current assets: Fixed-price contracts and other derivatives [Member]
Derivatives not designated as hedging instruments:
Net amounts presented on the balance sheet	3	2
Additional cash collateral for commodity contracts subject to rate recovery	3	1
Total	6	3
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: Fixed-price contracts and other derivatives [Member]
Derivatives not designated as hedging instruments:
Net amounts presented on the balance sheet	(5)	(2)
Additional cash collateral for commodity contracts subject to rate recovery	0	0
Total	(5)	(2)
Southern California Gas Company [Member] | Deferred credits and other liabilities: Fixed-price contracts and other derivatives [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: Fixed-price contracts and other derivatives [Member]
Derivatives not designated as hedging instruments:
Commodity contracts subject to rate recovery	3	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
Southern California Gas Company [Member] | Not Designated as Hedging Instrument [Member] | Current liabilities: Fixed-price contracts and other derivatives [Member]
Derivatives not designated as hedging instruments:
Commodity contracts subject to rate recovery	(5)	(2)
Southern California Gas Company [Member] | Not Designated as Hedging Instrument [Member] | Deferred credits and other liabilities: Fixed-price contracts and other derivatives [Member]
Derivatives not designated as hedging instruments:
Commodity contracts subject to rate recovery	0	$ 0
Sempra Renewables [Member] | Disposal Group Held-for-sale [Member]
Derivatives not designated as hedging instruments:
Fixed-price contracts and other derivatives, current	1
Fixed-price contracts and other derivatives, noncurrent	$ 2