DERIVATIVE FINANCIAL INSTRUMENTS - BALANCE SHEET (Details) - USD ($)	Dec. 31, 2020	Dec. 31, 2019
Current assets: Other [Member]
Other Derivatives Not Designated as Hedging Instruments at Fair Value, Net [Abstract]
Net amount presented on balance sheet	$ 57,000,000	$ 58,000,000
Additional margin posted for commodity contracts not subject to rate recovery	21,000,000	43,000,000
Additional margin posted for commodity contracts subject to rate recovery	30,000,000	25,000,000
Total	108,000,000	126,000,000
Other assets: Other long-term assets [Member]
Other Derivatives Not Designated as Hedging Instruments at Fair Value, Net [Abstract]
Net amount presented on balance sheet	100,000,000	85,000,000
Additional margin posted for commodity contracts not subject to rate recovery	0	0
Additional margin posted for commodity contracts subject to rate recovery	0	0
Total	100,000,000	85,000,000
Current liabilities: Other [Member]
Other Derivatives Not Designated as Hedging Instruments at Fair Value, Net [Abstract]
Net amount presented on balance sheet	(72,000,000)	(53,000,000)
Additional margin posted for commodity contracts not subject to rate recovery	0	0
Additional margin posted for commodity contracts subject to rate recovery	0	0
Total	(72,000,000)	(53,000,000)
Deferred credits and other liabilities: Deferred credits and other [Member]
Other Derivatives Not Designated as Hedging Instruments at Fair Value, Net [Abstract]
Net amount presented on balance sheet	(188,000,000)	(192,000,000)
Additional margin posted for commodity contracts not subject to rate recovery	0	0
Additional margin posted for commodity contracts subject to rate recovery	0	0
Total	(188,000,000)	(192,000,000)
Designated as Hedging Instrument [Member] | Current assets: Other [Member]
Derivative Instruments in Hedges, at Fair Value, Net [Abstract]
Interest rate and foreign exchange instruments	0	0
Designated as Hedging Instrument [Member] | Other assets: Other long-term assets [Member]
Derivative Instruments in Hedges, at Fair Value, Net [Abstract]
Interest rate and foreign exchange instruments	1,000,000	3,000,000
Designated as Hedging Instrument [Member] | Current liabilities: Other [Member]
Derivative Instruments in Hedges, at Fair Value, Net [Abstract]
Interest rate and foreign exchange instruments	(26,000,000)	(17,000,000)
Designated as Hedging Instrument [Member] | Deferred credits and other liabilities: Deferred credits and other [Member]
Derivative Instruments in Hedges, at Fair Value, Net [Abstract]
Interest rate and foreign exchange instruments	(160,000,000)	(140,000,000)
Not Designated as Hedging Instrument [Member] | Current assets: Other [Member]
Other Derivatives Not Designated as Hedging Instruments at Fair Value, Net [Abstract]
Foreign exchange instruments	24,000,000	41,000,000
Associated offsetting foreign exchange instruments		(20,000,000)
Commodity contracts not subject to rate recovery	82,000,000	34,000,000
Associated offsetting commodity contracts not subject to rate recovery	(82,000,000)	(32,000,000)
Commodity contracts subject to rate recovery	35,000,000	41,000,000
Associated offsetting commodity contracts subject to rate recovery	(2,000,000)	(6,000,000)
Associated cash collateral commodity contracts subject to rate recovery		0
Not Designated as Hedging Instrument [Member] | Other assets: Other long-term assets [Member]
Other Derivatives Not Designated as Hedging Instruments at Fair Value, Net [Abstract]
Foreign exchange instruments	0	0
Associated offsetting foreign exchange instruments		0
Commodity contracts not subject to rate recovery	17,000,000	11,000,000
Associated offsetting commodity contracts not subject to rate recovery	(13,000,000)	(2,000,000)
Commodity contracts subject to rate recovery	95,000,000	76,000,000
Associated offsetting commodity contracts subject to rate recovery	0	(3,000,000)
Associated cash collateral commodity contracts subject to rate recovery		0
Not Designated as Hedging Instrument [Member] | Current liabilities: Other [Member]
Other Derivatives Not Designated as Hedging Instruments at Fair Value, Net [Abstract]
Foreign exchange instruments	0	(20,000,000)
Associated offsetting foreign exchange instruments		20,000,000
Commodity contracts not subject to rate recovery	(95,000,000)	(41,000,000)
Associated offsetting commodity contracts not subject to rate recovery	82,000,000	32,000,000
Commodity contracts subject to rate recovery	(35,000,000)	(47,000,000)
Associated offsetting commodity contracts subject to rate recovery	2,000,000	6,000,000
Associated cash collateral commodity contracts subject to rate recovery		14,000,000
Not Designated as Hedging Instrument [Member] | Deferred credits and other liabilities: Deferred credits and other [Member]
Other Derivatives Not Designated as Hedging Instruments at Fair Value, Net [Abstract]
Foreign exchange instruments	0	0
Associated offsetting foreign exchange instruments		0
Commodity contracts not subject to rate recovery	(16,000,000)	(10,000,000)
Associated offsetting commodity contracts not subject to rate recovery	13,000,000	2,000,000
Commodity contracts subject to rate recovery	(25,000,000)	(47,000,000)
Associated offsetting commodity contracts subject to rate recovery	0	3,000,000
Associated cash collateral commodity contracts subject to rate recovery		0
San Diego Gas and Electric Company [Member] | Current assets: Other [Member]
Other Derivatives Not Designated as Hedging Instruments at Fair Value, Net [Abstract]
Net amount presented on balance sheet	31,000,000	26,000,000
Additional margin posted for commodity contracts subject to rate recovery	24,000,000	16,000,000
Total	55,000,000	42,000,000
San Diego Gas and Electric Company [Member] | Other assets: Other long-term assets [Member]
Other Derivatives Not Designated as Hedging Instruments at Fair Value, Net [Abstract]
Net amount presented on balance sheet	95,000,000	73,000,000
Additional margin posted for commodity contracts subject to rate recovery	0	0
Total	95,000,000	73,000,000
San Diego Gas and Electric Company [Member] | Current liabilities: Other [Member]
Other Derivatives Not Designated as Hedging Instruments at Fair Value, Net [Abstract]
Net amount presented on balance sheet	(27,000,000)	(23,000,000)
Additional margin posted for commodity contracts subject to rate recovery	0	0
Total	(27,000,000)	(23,000,000)
San Diego Gas and Electric Company [Member] | Deferred credits and other liabilities: Deferred credits and other [Member]
Other Derivatives Not Designated as Hedging Instruments at Fair Value, Net [Abstract]
Net amount presented on balance sheet	(25,000,000)	(44,000,000)
Additional margin posted for commodity contracts subject to rate recovery	0	0
Total	(25,000,000)	(44,000,000)
San Diego Gas and Electric Company [Member] | Not Designated as Hedging Instrument [Member] | Current assets: Other [Member]
Other Derivatives Not Designated as Hedging Instruments at Fair Value, Net [Abstract]
Commodity contracts subject to rate recovery	32,000,000	30,000,000
Associated offsetting commodity contracts subject to rate recovery	(1,000,000)	(4,000,000)
Associated cash collateral commodity contracts subject to rate recovery		0
San Diego Gas and Electric Company [Member] | Not Designated as Hedging Instrument [Member] | Other assets: Other long-term assets [Member]
Other Derivatives Not Designated as Hedging Instruments at Fair Value, Net [Abstract]
Commodity contracts subject to rate recovery	95,000,000	76,000,000
Associated offsetting commodity contracts subject to rate recovery	0	(3,000,000)
Associated cash collateral commodity contracts subject to rate recovery		0
San Diego Gas and Electric Company [Member] | Not Designated as Hedging Instrument [Member] | Current liabilities: Other [Member]
Other Derivatives Not Designated as Hedging Instruments at Fair Value, Net [Abstract]
Commodity contracts subject to rate recovery	(28,000,000)	(41,000,000)
Associated offsetting commodity contracts subject to rate recovery	1,000,000	4,000,000
Associated cash collateral commodity contracts subject to rate recovery		14,000,000
San Diego Gas and Electric Company [Member] | Not Designated as Hedging Instrument [Member] | Deferred credits and other liabilities: Deferred credits and other [Member]
Other Derivatives Not Designated as Hedging Instruments at Fair Value, Net [Abstract]
Commodity contracts subject to rate recovery	(25,000,000)	(47,000,000)
Associated offsetting commodity contracts subject to rate recovery	0	3,000,000
Associated cash collateral commodity contracts subject to rate recovery		0
Southern California Gas Company [Member] | Current assets: Other [Member]
Other Derivatives Not Designated as Hedging Instruments at Fair Value, Net [Abstract]
Net amount presented on balance sheet	2,000,000	9,000,000
Additional margin posted for commodity contracts subject to rate recovery	6,000,000	9,000,000
Total	8,000,000	18,000,000
Southern California Gas Company [Member] | Other assets: Other long-term assets [Member]
Other Derivatives Not Designated as Hedging Instruments at Fair Value, Net [Abstract]
Net amount presented on balance sheet	0	0
Additional margin posted for commodity contracts subject to rate recovery	0	0
Total	0	0
Southern California Gas Company [Member] | Current liabilities: Other [Member]
Other Derivatives Not Designated as Hedging Instruments at Fair Value, Net [Abstract]
Net amount presented on balance sheet	(6,000,000)	(4,000,000)
Additional margin posted for commodity contracts subject to rate recovery	0	0
Total	(6,000,000)	(4,000,000)
Southern California Gas Company [Member] | Deferred credits and other liabilities: Deferred credits and other [Member]
Other Derivatives Not Designated as Hedging Instruments at Fair Value, Net [Abstract]
Net amount presented on balance sheet	0	0
Additional margin posted 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]
Other Derivatives Not Designated as Hedging Instruments at Fair Value, Net [Abstract]
Commodity contracts subject to rate recovery	3,000,000	11,000,000
Associated offsetting commodity contracts subject to rate recovery	(1,000,000)	(2,000,000)
Southern California Gas Company [Member] | Not Designated as Hedging Instrument [Member] | Other assets: Other long-term assets [Member]
Other Derivatives Not Designated as Hedging Instruments at Fair Value, Net [Abstract]
Commodity contracts subject to rate recovery	0	0
Associated offsetting commodity contracts subject to rate recovery	0	0
Southern California Gas Company [Member] | Not Designated as Hedging Instrument [Member] | Current liabilities: Other [Member]
Other Derivatives Not Designated as Hedging Instruments at Fair Value, Net [Abstract]
Commodity contracts subject to rate recovery	(7,000,000)	(6,000,000)
Associated offsetting commodity contracts subject to rate recovery	1,000,000	2,000,000
Southern California Gas Company [Member] | Not Designated as Hedging Instrument [Member] | Deferred credits and other liabilities: Deferred credits and other [Member]
Other Derivatives Not Designated as Hedging Instruments at Fair Value, Net [Abstract]
Commodity contracts subject to rate recovery	0	0
Associated offsetting commodity contracts subject to rate recovery	$ 0	$ 0