GENERAL INFORMATION AND OTHER FINANCIAL DATA - PENSION AND OTHER POSTRETIREMENT BENEFITS (Details) - USD ($) $ in Millions		3 Months Ended		9 Months Ended
	Mar. 09, 2018	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Pension benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost		$ 29	$ 31	$ 95	$ 88
Interest cost		36	39	105	113
Expected return on assets		(36)	(41)	(117)	(121)
Prior service cost (credit)		3	3	8	8
Actuarial loss (gain)		7	11	26	27
Settlements		9	8	48	8
Special termination benefits		0	0	0	0
Net periodic benefit cost (credit)		48	51	165	123
Regulatory adjustment		(11)	(18)	(91)	(59)
Total expense recognized		37	33	74	64
Contributions by employer				76
Expected contributions in current fiscal year		192		192
Pension benefits [Member] | San Diego Gas and Electric Company [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost		7	7	23	22
Interest cost		9	9	26	28
Expected return on assets		(10)	(11)	(35)	(35)
Prior service cost (credit)				1	1
Actuarial loss (gain)		0	3	3	7
Settlements			0		0
Special termination benefits		0	0	0	0
Net periodic benefit cost (credit)		7	8	35	23
Regulatory adjustment		(7)	(7)	(34)	(21)
Total expense recognized		0	1	1	2
Contributions by employer				3
Expected contributions in current fiscal year		48		48
Pension benefits [Member] | Southern California Gas Company [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost		19	21	62	57
Interest cost		23	25	68	73
Expected return on assets		(22)	(26)	(73)	(77)
Prior service cost (credit)		2	3	6	7
Actuarial loss (gain)		3	6	15	14
Settlements			0		0
Special termination benefits		0	0	0	0
Net periodic benefit cost (credit)		27	29	103	74
Regulatory adjustment		(4)	(11)	(57)	(38)
Total expense recognized		23	18	46	36
Contributions by employer				46
Expected contributions in current fiscal year		105		105
Other postretirement benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost		4	4	15	15
Interest cost		9	9	27	29
Expected return on assets		(18)	(16)	(53)	(49)
Prior service cost (credit)		0	0	0	0
Actuarial loss (gain)		(2)	(2)	(4)	(3)
Settlements		0	0	0	0
Special termination benefits		5	16	5	16
Net periodic benefit cost (credit)		(2)	11	(10)	8
Regulatory adjustment		2	(11)	11	(7)
Total expense recognized		0	0	1	1
Contributions by employer				2
Expected contributions in current fiscal year		6		6
Other postretirement benefits [Member] | San Diego Gas and Electric Company [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost		1	1	3	4
Interest cost		2	2	5	6
Expected return on assets		(3)	(2)	(10)	(9)
Prior service cost (credit)				2	2
Actuarial loss (gain)		(1)	0	(2)	0
Settlements		0	0	0	0
Special termination benefits		3	0	3	0
Net periodic benefit cost (credit)		2	1	1	3
Regulatory adjustment		(2)	(1)	(1)	(3)
Total expense recognized		0	0	0	0
Contributions by employer				0
Expected contributions in current fiscal year		1		1
Other postretirement benefits [Member] | Southern California Gas Company [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost		3	4	11	11
Interest cost		6	6	20	21
Expected return on assets		(13)	(14)	(41)	(40)
Prior service cost (credit)		(1)	(1)	(2)	(2)
Actuarial loss (gain)		(1)	(1)	(2)	(2)
Settlements		0	0	0	0
Special termination benefits		2	16	2	16
Net periodic benefit cost (credit)		(4)	10	(12)	4
Regulatory adjustment		4	(10)	12	(4)
Total expense recognized		0	$ 0	0	$ 0
Contributions by employer				1
Expected contributions in current fiscal year		2		2
Oncor Holdings [Member] | Sempra Texas Holdings Corp [Member] | Other postretirement benefits [Member] | Sempra Texas Intermediate Holding Company LLC [Member]
Defined Benefit Plan Disclosure [Line Items]
Increase in liability due to acquisition	$ 21
Qualified Plan [Member] | Pension benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Reduction in plan assets due to settlement				300
Settlements		(3)		(42)
Qualified Plan [Member] | Pension benefits [Member] | San Diego Gas and Electric Company [Member]
Defined Benefit Plan Disclosure [Line Items]
Reduction in plan assets due to settlement				108
Settlements		1		17
Qualified Plan [Member] | Pension benefits [Member] | Southern California Gas Company [Member]
Defined Benefit Plan Disclosure [Line Items]
Reduction in plan assets due to settlement				192
Settlements		$ 2		$ 25