DERIVATIVE FINANCIAL INSTRUMENTS - DERIVATIVE IMPACT ON INCOME (Details) - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Derivative Instruments, Gain (Loss) [Line Items]
Pretax gain (loss) on derivatives recognized in earnings			$ 142,000,000	$ (39,000,000)
Fair Value Hedging [Member] | Interest Expense [Member] | Interest rate instruments [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Hedge ineffectiveness				0
Designated as Hedging Instrument [Member] | Fair Value Hedging [Member] | Interest rate instruments [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Pretax gain (loss) on derivatives recognized in earnings				1,000,000
Designated as Hedging Instrument [Member] | Fair Value Hedging [Member] | Interest Expense [Member] | Interest rate instruments [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Pretax gain (loss) on derivatives recognized in earnings				3,000,000
Designated as Hedging Instrument [Member] | Fair Value Hedging [Member] | Other Income, Net [Member] | Interest rate instruments [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Pretax gain (loss) on derivatives recognized in earnings				(2,000,000)
Designated as Hedging Instrument [Member] | Cash Flow Hedging [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Pretax gain (loss) recognized in OCI	$ 17,000,000	$ 16,000,000	(37,000,000)	(238,000,000)
Pretax (loss) gain reclassified from AOCI into earnings	2,000,000	(12,000,000)	(13,000,000)	(23,000,000)
Loss on cash flow hedge ineffectiveness	2,000,000	0	4,000,000	0
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	14,000,000	(16,000,000)	22,000,000	(26,000,000)
Pretax (loss) gain reclassified from AOCI into earnings	0	(4,000,000)	4,000,000	(11,000,000)
Designated as Hedging Instrument [Member] | Cash Flow Hedging [Member] | Equity Earnings, Before Income Tax [Member] | Interest rate instruments [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Pretax gain (loss) recognized in OCI	(9,000,000)	17,000,000	(46,000,000)	(190,000,000)
Pretax (loss) gain reclassified from AOCI into earnings	(2,000,000)	(3,000,000)	(6,000,000)	(8,000,000)
Designated as Hedging Instrument [Member] | Cash Flow Hedging [Member] | Remeasurement of Equity Method Investment [Member] | Interest rate and foreign exchange instruments [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Pretax gain (loss) recognized in OCI	0	0	0	0
Pretax (loss) gain reclassified from AOCI into earnings	0	(7,000,000)	0	(7,000,000)
Designated as Hedging Instrument [Member] | Cash Flow Hedging [Member] | Equity Earnings, Net of Income Tax [Member] | Interest rate and foreign exchange instruments [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Pretax gain (loss) recognized in OCI	7,000,000	13,000,000	(11,000,000)	(20,000,000)
Pretax (loss) gain reclassified from AOCI into earnings	2,000,000	2,000,000	(3,000,000)	(4,000,000)
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	5,000,000	0	(5,000,000)	0
Pretax (loss) gain reclassified from AOCI into earnings	2,000,000	0	1,000,000	0
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	2,000,000	3,000,000	(2,000,000)
Pretax (loss) gain reclassified from AOCI into earnings	0	0	(9,000,000)	7,000,000
Not Designated as Hedging Instrument [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Pretax gain (loss) on derivatives recognized in earnings	60,000,000	(125,000,000)	163,000,000	(137,000,000)
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	4,000,000	(11,000,000)	101,000,000	(23,000,000)
Not Designated as Hedging Instrument [Member] | Equity Earnings, Net of Income Tax [Member] | Foreign exchange instruments [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Pretax gain (loss) on derivatives recognized in earnings	1,000,000	1,000,000	1,000,000	3,000,000
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	(3,000,000)	3,000,000	27,000,000	(26,000,000)
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	(1,000,000)	1,000,000
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	59,000,000	(118,000,000)	36,000,000	(90,000,000)
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	(1,000,000)	0	(1,000,000)	(2,000,000)
San Diego Gas and Electric Company [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Pretax gain (loss) on derivatives recognized in earnings			1,000,000	2,000,000
San Diego Gas and Electric Company [Member] | Cash Flow Hedging [Member] | Interest Expense [Member] | Interest rate instruments [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Loss on cash flow hedge ineffectiveness	0	0	0	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	0	2,000,000	(2,000,000)	(5,000,000)
Pretax (loss) gain reclassified from AOCI into earnings	(3,000,000)	(3,000,000)	(9,000,000)	(9,000,000)
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	59,000,000	(118,000,000)	36,000,000	(90,000,000)
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 gain (loss) recognized in OCI	0	0	0	0
Pretax (loss) gain reclassified from AOCI into earnings	0	(1,000,000)	0	(1,000,000)
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	(1,000,000)	(2,000,000)
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	1,000,000	0	0	0
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	$ (1,000,000)	$ 0	$ (1,000,000)	$ (2,000,000)