GENERAL INFORMATION AND OTHER FINANCIAL DATA - PENSION AND OTHER POSTRETIREMENT BENEFITS (Details) - USD ($) $ in Millions		3 Months Ended		6 Months Ended
	Mar. 09, 2018	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Pension benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Reduction in plan assets due to settlement				$ 274
Service cost		$ 33	$ 29	66	$ 57
Interest cost		34	37	69	74
Expected return on assets		(39)	(40)	(81)	(80)
Prior service cost (credit)		2	2	5	5
Actuarial loss (gain)		10	8	19	16
Settlements		25	0	39	0
Net periodic benefit cost (credit)		65	36	117	72
Regulatory adjustment		(35)	(29)	(80)	(41)
Total expense recognized		30	7	37	31
Contributions by employer				37
Expected contributions in current fiscal year		226		226
Pension benefits [Member] | San Diego Gas and Electric Company [Member]
Defined Benefit Plan Disclosure [Line Items]
Reduction in plan assets due to settlement				97
Service cost		8	7	16	15
Interest cost		8	10	17	19
Expected return on assets		(12)	(13)	(25)	(24)
Prior service cost (credit)		1	1	1	1
Actuarial loss (gain)		2	2	3	4
Settlements		2	0	16	0
Net periodic benefit cost (credit)		9	7	28	15
Regulatory adjustment		(8)	(7)	(27)	(14)
Total expense recognized		1	0	1	1
Contributions by employer				2
Expected contributions in current fiscal year		48		48
Pension benefits [Member] | Southern California Gas Company [Member]
Defined Benefit Plan Disclosure [Line Items]
Reduction in plan assets due to settlement		177
Service cost		21	18	43	36
Interest cost		22	24	45	48
Expected return on assets		(25)	(25)	(51)	(51)
Prior service cost (credit)		2	2	4	4
Actuarial loss (gain)		6	4	12	8
Settlements		23	0	23	0
Net periodic benefit cost (credit)		49	23	76	45
Regulatory adjustment		(27)	(22)	(53)	(27)
Total expense recognized		22	1	23	18
Contributions by employer				23
Expected contributions in current fiscal year		113		113
Other postretirement benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost		5	5	11	11
Interest cost		9	11	18	20
Expected return on assets		(17)	(17)	(35)	(33)
Prior service cost (credit)		0	0	0	0
Actuarial loss (gain)		(1)	0	(2)	(1)
Settlements		0	0	0	0
Net periodic benefit cost (credit)		(4)	(1)	(8)	(3)
Regulatory adjustment		5	2	9	4
Total expense recognized		1	1	1	1
Contributions by employer				2
Expected contributions in current fiscal year		9		9
Other postretirement benefits [Member] | San Diego Gas and Electric Company [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost		1	2	2	3
Interest cost		1	2	3	4
Expected return on assets		(4)	(4)	(7)	(7)
Prior service cost (credit)		1	1	2	2
Actuarial loss (gain)		0	0	(1)	0
Settlements		0	0	0	0
Net periodic benefit cost (credit)		(1)	1	(1)	2
Regulatory adjustment		1	(1)	1	(2)
Total expense recognized		0	0	0	0
Contributions by employer				0
Expected contributions in current fiscal year		3		3
Other postretirement benefits [Member] | Southern California Gas Company [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost		4	3	8	7
Interest cost		7	8	14	15
Expected return on assets		(14)	(13)	(28)	(26)
Prior service cost (credit)		0	0	(1)	(1)
Actuarial loss (gain)		(1)	(1)	(1)	(1)
Settlements		0	0	0	0
Net periodic benefit cost (credit)		(4)	(3)	(8)	(6)
Regulatory adjustment		4	3	8	6
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