DERIVATIVE FINANCIAL INSTRUMENTS - INCOME STATEMENT (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Designated as Hedging Instrument [Member] | Cash Flow Hedging [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Pretax (loss) gain recognized in OCI	$ (232)	$ (187)	$ 68
Pretax (loss) gain reclassified from AOCI into earnings	(67)	(11)	(13)
Designated as Hedging Instrument [Member] | Cash Flow Hedging [Member] | (Loss) Gain on Sale of Assets [Member] | Interest rate instruments [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Pretax (loss) gain recognized in OCI	0	0	0
Pretax (loss) gain reclassified from AOCI into earnings	0	(10)	(9)
Designated as Hedging Instrument [Member] | Cash Flow Hedging [Member] | Interest Expense [Member] | Interest rate instruments [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Pretax (loss) gain recognized in OCI	(34)	(24)	17
Pretax (loss) gain reclassified from AOCI into earnings	(10)	(3)	(1)
Designated as Hedging Instrument [Member] | Cash Flow Hedging [Member] | Interest Expense [Member] | Interest rate and foreign exchange instruments [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Pretax (loss) gain recognized in OCI	(6)	19	14
Pretax (loss) gain reclassified from AOCI into earnings	(1)	0	1
Designated as Hedging Instrument [Member] | Cash Flow Hedging [Member] | Equity Earnings [Member] | Interest rate instruments [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Pretax (loss) gain recognized in OCI	(185)	(164)	44
Pretax (loss) gain reclassified from AOCI into earnings	(46)	(3)	(9)
Designated as Hedging Instrument [Member] | Cash Flow Hedging [Member] | Equity Earnings [Member] | Foreign exchange instruments [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Pretax (loss) gain recognized in OCI	(3)	(10)	(3)
Pretax (loss) gain reclassified from AOCI into earnings	0	(2)	2
Designated as Hedging Instrument [Member] | Cash Flow Hedging [Member] | Revenues: Energy-Related Businesses [Member] | Foreign exchange instruments [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Pretax (loss) gain recognized in OCI	(4)	(8)	(4)
Pretax (loss) gain reclassified from AOCI into earnings	1	(2)	1
Designated as Hedging Instrument [Member] | Cash Flow Hedging [Member] | Other (Expense) Income, Net [Member] | Interest rate and foreign exchange instruments [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Pretax (loss) gain reclassified from AOCI into earnings	(11)	9	2
Not Designated as Hedging Instrument [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Gain (loss) on derivative recognized in earnings	42	(100)	313
Not Designated as Hedging Instrument [Member] | Revenues: Energy-Related Businesses [Member] | Commodity Contracts Not Subject To Rate Recovery [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Gain (loss) on derivative recognized in earnings	17	12	26
Not Designated as Hedging Instrument [Member] | Other (Expense) Income, Net [Member] | Foreign exchange instruments [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Gain (loss) on derivative recognized in earnings	(56)	25	3
Not Designated as Hedging Instrument [Member] | Cost of Electric Fuel and Purchased Power [Member] | Commodity contracts subject to rate recovery [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Gain (loss) on derivative recognized in earnings	88	(140)	279
Not Designated as Hedging Instrument [Member] | Cost of Natural Gas [Member] | Commodity contracts subject to rate recovery [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Gain (loss) on derivative recognized in earnings	(7)	3	5
San Diego Gas and Electric Company [Member] | Designated as Hedging Instrument [Member] | Cash Flow Hedging [Member] | Interest Expense [Member] | Interest rate instruments [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Pretax (loss) gain recognized in OCI	0	(1)	1
Pretax (loss) gain reclassified from AOCI into earnings	0	(3)	(7)
San Diego Gas and Electric Company [Member] | Not Designated as Hedging Instrument [Member] | Cost of Electric Fuel and Purchased Power [Member] | Commodity contracts subject to rate recovery [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Gain (loss) on derivative recognized in earnings	88	(140)	279
Southern California Gas Company [Member] | Designated as Hedging Instrument [Member] | Cash Flow Hedging [Member] | Interest Expense [Member] | Interest rate instruments [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Pretax (loss) gain recognized in OCI	0	0	0
Pretax (loss) gain reclassified from AOCI into earnings	0	(1)	(1)
Southern California Gas Company [Member] | Not Designated as Hedging Instrument [Member] | Cost of Natural Gas [Member] | Commodity contracts subject to rate recovery [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Gain (loss) on derivative recognized in earnings	$ (7)	$ 3	$ 5