DERIVATIVE FINANCIAL INSTRUMENTS - DERIVATIVE IMPACT ON INCOME (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Derivative Instruments, Gain (Loss) [Line Items]
Pretax gain (loss) on derivatives recognized in earnings			$ 9	$ 142	[1]
Designated as Hedging Instrument [Member] | Cash Flow Hedging [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Pretax (loss) gain recognized in OCI	$ 25	$ (50)	142	(54)
Pretax (loss) gain reclassified from AOCI into earnings	(19)	(3)	(3)	(15)
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	(13)	(8)	41	8
Pretax (loss) gain reclassified from AOCI into earnings	(1)	1	1	4
Designated as Hedging Instrument [Member] | Cash Flow Hedging [Member] | Other Income, Net [Member] | Interest rate and foreign exchange instruments [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Pretax (loss) gain reclassified from AOCI into earnings	(18)	0
Designated as Hedging Instrument [Member] | Cash Flow Hedging [Member] | Equity Losses [Member] | Interest rate and foreign exchange instruments [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Pretax (loss) gain recognized in OCI	33	(41)	103	(55)
Pretax (loss) gain reclassified from AOCI into earnings	(1)	(5)	(5)	(9)
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	5	(1)	(2)	(10)
Pretax (loss) gain reclassified from AOCI into earnings	1	1	1	(1)
Designated as Hedging Instrument [Member] | Cash Flow Hedging [Member] | Revenues: Energy- Related Businesses [Member] | Commodity contracts not subject to rate recovery [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Pretax (loss) gain recognized in OCI			0	3
Pretax (loss) gain reclassified from AOCI into earnings			0	(9)
Not Designated as Hedging Instrument [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Pretax gain (loss) on derivatives recognized in earnings	(31)	54	7	103
Not Designated as Hedging Instrument [Member] | Other Income, Net [Member] | Foreign exchange instruments [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Pretax gain (loss) on derivatives recognized in earnings	(37)	32	7	97
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]
Pretax gain (loss) on derivatives recognized in earnings	0	16	(9)	30
Not Designated as Hedging Instrument [Member] | Operation and Maintenance [Member] | Commodity contracts not subject to rate recovery [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Pretax gain (loss) on derivatives recognized in earnings	0	0	0	(1)
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]
Pretax gain (loss) on derivatives recognized in earnings	6	6	8	(23)
Not Designated as Hedging Instrument [Member] | Cost of Natural Gas [Member] | Commodity contracts subject to rate recovery [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Pretax gain (loss) on derivatives recognized in earnings	0	0	1	0
San Diego Gas and Electric Company [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Pretax gain (loss) on derivatives recognized in earnings			1	1
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	(2)	1	(2)
Pretax (loss) gain reclassified from AOCI into earnings	(1)	(3)	(4)	(6)
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]
Pretax gain (loss) on derivatives recognized in earnings	6	6	8	(23)
Southern California Gas Company [Member] | Not Designated as Hedging Instrument [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Pretax gain (loss) on derivatives recognized in earnings	0	0	1	(1)
Southern California Gas Company [Member] | Not Designated as Hedging Instrument [Member] | Operation and Maintenance [Member] | Commodity contracts not subject to rate recovery [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Pretax gain (loss) on derivatives recognized in earnings	0	0	0	(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]
Pretax gain (loss) on derivatives recognized in earnings	$ 0	$ 0	$ 1	$ 0

[1] As adjusted for the retrospective adoption of ASU 2016-18, which we discuss in Note 2.