OTHER FINANCIAL DATA - VARIABLE INTEREST ENTITIES (Details) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2017 USD ($)	Sep. 30, 2016 USD ($)	Sep. 30, 2017 USD ($) MW	Sep. 30, 2016 USD ($)	Dec. 31, 2016 USD ($)
Variable Interest Entities [Line Items]
Property, plant and equipment, net	$ 35,384		$ 35,384		$ 32,931	[1]
Other noncontrolling interests	2,217		2,217		2,270	[1]
Energy-related businesses	402	$ 271	1,071	$ 613
Operation and maintenance	(762)	(703)	(2,207)	(2,109)
Depreciation and amortization	(378)	(328)	(1,106)	(970)
Interest expense	(165)	(136)	(493)	(421)
Income before income taxes	15	982	1,185	1,325
Income tax benefit (expense)	84	(282)	(378)	(284)
Income (loss) before income taxes/Net income (loss)	102	719	802	1,110
(Earnings) losses attributable to noncontrolling interest	(45)	(97)	(44)	(118)
Earnings attributable to common shares	57	622	757	991
Otay Mesa VIE [Member]
Variable Interest Entities [Line Items]
Property, plant and equipment, net	328		328		354
Sempra Renewables [Member] | Tax Equity Investors [Member]
Variable Interest Entities [Line Items]
Property, plant and equipment, net	904		904		926
Other noncontrolling interests	445		445		468
Energy-related businesses	17		48
Operation and maintenance	(5)		(14)
Depreciation and amortization	(8)		(24)
Income before income taxes	4		10
Income tax benefit (expense)	(3)		(9)
Income (loss) before income taxes/Net income (loss)	1		1
(Earnings) losses attributable to noncontrolling interest	6		16
Earnings attributable to common shares	7		17
Sempra Natural Gas [Member] | Cameron LNG Holdings [Member]
Investments [Abstract]
Carrying value of equity method investment	980		980		997
San Diego Gas and Electric Company [Member]
Variable Interest Entities [Line Items]
Property, plant and equipment, net	14,434		14,434		13,250	[1]
Other noncontrolling interests	35		35		37	[1]
Operation and maintenance	249	268	713	780
Depreciation and amortization	170	161	499	478
Operating income	(54)	323	465	729
Interest expense	(53)	(49)	(151)	(145)
Income before income taxes	(91)	285	363	622
Income tax benefit (expense)	72	(91)	(72)	(204)
Income (loss) before income taxes/Net income (loss)	(19)	194	291	418
(Earnings) losses attributable to noncontrolling interest	(9)	(11)	$ (15)	1
San Diego Gas and Electric Company [Member] | Otay Mesa VIE [Member]
Variable Interest Entities [Line Items]
Generating capacity (in mw) | MW			605
Conditional purchase obligation	280		$ 280
Equity of variable interest entity	35		35		37
Secured debt of variable interest entity	297		297
Property, plant and equipment, net	328		328		$ 354
Cost of electric fuel and purchased power	(26)	(28)	(65)	(62)
Operation and maintenance	4	4	13	23
Depreciation and amortization	7	8	21	25
Total operating expenses	(15)	(16)	(31)	(14)
Operating income	15	16	31	14
Interest expense	(6)	(5)	(16)	(15)
Income (loss) before income taxes/Net income (loss)	9	11	15	(1)
(Earnings) losses attributable to noncontrolling interest	(9)	(11)	(15)	1
Earnings attributable to common shares	$ 0	$ 0	$ 0	$ 0

[1] Derived from audited financial statements.