DERIVATIVE FINANCIAL INSTRUMENTS - DERIVATIVE IMPACT ON INCOME (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Derivative Instruments, Gain (Loss) [Line Items]
Pretax gain (loss) on derivatives recognized in earnings	$ 35	$ 106	[1]
Designated as Hedging Instrument [Member] | Cash Flow Hedging [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Pretax gain (loss) recognized in OCI	117	(4)
Pretax (loss) gain reclassified from AOCI into earnings	16	(12)
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 gain (loss) recognized in OCI	54	16
Pretax (loss) gain reclassified from AOCI into earnings	2	3
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 gain (loss) recognized in OCI	70	(14)
Pretax (loss) gain reclassified from AOCI into earnings	(4)	(4)
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 gain (loss) recognized in OCI	(7)	(9)
Pretax (loss) gain reclassified from AOCI into earnings	0	(2)
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 gain (loss) 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	38	49
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	44	65
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	(9)	14
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	(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	2	(29)
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	1	0
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 gain (loss) recognized in OCI	1	0
Pretax (loss) gain reclassified from AOCI into earnings	(3)	(3)
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	2	(29)
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	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	(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	$ 1	$ 0

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