OTHER FINANCIAL DATA - RECLASSIFICATION FROM ACCUMULATED OTHER COMPREHENSIVE INCOME (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Interest expense	$ (165)	$ (136)	$ (493)	$ (421)
Equity earnings, before income tax	10	12	31	4
Remeasurement of equity method investment	0	617	0	617
Equity earnings (losses), net of income tax	3	19	(5)	69
Revenues: Energy-Related Businesses	402	271	1,071	613
Income before income taxes and equity (losses) earnings of certain unconsolidated subsidiaries	15	982	1,185	1,325
Income Tax Benefit (Expense)	84	(282)	(378)	(284)
Earnings Attributable to Noncontrolling Interests	(45)	(97)	(44)	(118)
Earnings (losses)	57	622	757	991
Total reclassifications for the period, net of tax	5	7	14	12
Gains (Losses) on Cash Flow hedges Attributable to Parent [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Total reclassifications for the period, net of tax	(2)	5	4	8
Gain (Loss) on Pension and Other Postretirement Benefits [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Amortization of actuarial loss	11	4	16	8
Pension and Other Postretirement Benefits [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Income tax expense	(4)	(2)	(6)	(4)
Total reclassifications for the period, net of tax	7	2	10	4
Reclassification out of Accumulated Other Comprehensive Income [Member] | Gains (Losses) on Cash Flow hedges [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Income before income taxes and equity (losses) earnings of certain unconsolidated subsidiaries	(2)	12	13	23
Income Tax Benefit (Expense)	1	(3)	(4)	(4)
Net of income tax	(1)	9	9	19
Reclassification out of Accumulated Other Comprehensive Income [Member] | Gains (Losses) on Cash Flow hedges [Member] | Interest rate and foreign exchange instruments [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Interest expense	0	4	(4)	11
Remeasurement of equity method investment	0	7	0	7
Equity earnings (losses), net of income tax	(2)	(2)	3	4
Reclassification out of Accumulated Other Comprehensive Income [Member] | Gains (Losses) on Cash Flow hedges [Member] | Foreign exchange instruments [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Revenues: Energy-Related Businesses	(2)	0	(1)	0
Reclassification out of Accumulated Other Comprehensive Income [Member] | Gains (Losses) on Cash Flow hedges [Member] | Interest rate instruments [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Equity earnings, before income tax	2	3	6	8
Reclassification out of Accumulated Other Comprehensive Income [Member] | Gains (Losses) on Cash Flow hedges [Member] | Commodity contracts not subject to rate recovery [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Revenues: Energy-Related Businesses			9	(7)
Reclassification out of Accumulated Other Comprehensive Income [Member] | Gains (Losses) on Cash Flow hedges Attributable to Noncontrolling Interests [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Earnings Attributable to Noncontrolling Interests	(1)	(4)	(5)	(11)
Reclassification out of Accumulated Other Comprehensive Income [Member] | Gains (Losses) on Cash Flow hedges Attributable to Parent [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Earnings (losses)	(2)	5	4	8
San Diego Gas and Electric Company [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Interest expense	(53)	(49)	(151)	(145)
Income before income taxes and equity (losses) earnings of certain unconsolidated subsidiaries	(91)	285	363	622
Income Tax Benefit (Expense)	72	(91)	(72)	(204)
Earnings Attributable to Noncontrolling Interests	(9)	(11)	(15)	1
Total reclassifications for the period, net of tax	1	0	1	0
San Diego Gas and Electric Company [Member] | Gain (Loss) on Pension and Other Postretirement Benefits [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Amortization of actuarial loss	1	0	1	0
San Diego Gas and Electric Company [Member] | Pension and Other Postretirement Benefits [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Total reclassifications for the period, net of tax	1		1
San Diego Gas and Electric Company [Member] | Reclassification out of Accumulated Other Comprehensive Income [Member] | Gains (Losses) on Cash Flow hedges [Member] | Interest rate instruments [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Interest expense	3	3	9	9
San Diego Gas and Electric Company [Member] | Reclassification out of Accumulated Other Comprehensive Income [Member] | Gains (Losses) on Cash Flow hedges Attributable to Noncontrolling Interests [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Earnings Attributable to Noncontrolling Interests	(3)	(3)	(9)	(9)
San Diego Gas and Electric Company [Member] | Reclassification out of Accumulated Other Comprehensive Income [Member] | Gains (Losses) on Cash Flow hedges Attributable to Parent [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Earnings (losses)	0	0	0	0
Southern California Gas Company [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Interest expense	(26)	(25)	(77)	(71)
Income before income taxes and equity (losses) earnings of certain unconsolidated subsidiaries	(7)	21	372	274
Income Tax Benefit (Expense)	14	(21)	(103)	(75)
Total reclassifications for the period, net of tax	0	1	1	1
Southern California Gas Company [Member] | Gains (Losses) on Cash Flow hedges Attributable to Parent [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Total reclassifications for the period, net of tax		1	0	1
Southern California Gas Company [Member] | Gain (Loss) on Pension and Other Postretirement Benefits [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Amortization of actuarial loss			1	0
Southern California Gas Company [Member] | Pension and Other Postretirement Benefits [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Total reclassifications for the period, net of tax		0	1	0
Southern California Gas Company [Member] | Reclassification out of Accumulated Other Comprehensive Income [Member] | Gains (Losses) on Cash Flow hedges [Member] | Interest rate instruments [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Interest expense	$ 0	$ 1	$ 0	$ 1