GENERAL INFORMATION AND OTHER FINANCIAL DATA - PENSION AND OTHER POSTRETIREMENT BENEFITS (Details) - USD ($) $ in Millions		3 Months Ended
	Mar. 09, 2018	Mar. 31, 2018	Mar. 31, 2017
Pension benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Reduction in plan assets due to settlement		$ 83
Service cost		33	$ 28
Interest cost		35	37
Expected return on assets		(42)	(40)
Prior service cost (credit)		3	3
Actuarial loss (gain)		9	8
Settlements		14	0
Net periodic benefit cost (credit)		52	36
Regulatory adjustment		(45)	(12)
Total expense recognized		7	24
Contributions by employer		10
Expected contributions in current fiscal year		226
Pension benefits [Member] | San Diego Gas and Electric Company [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost		8	8
Interest cost		9	9
Expected return on assets		(13)	(11)
Prior service cost (credit)		0	0
Actuarial loss (gain)		1	2
Settlements		14	0
Net periodic benefit cost (credit)		19	8
Regulatory adjustment		(19)	(7)
Total expense recognized		0	1
Contributions by employer		2
Expected contributions in current fiscal year		48
Pension benefits [Member] | Southern California Gas Company [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost		22	18
Interest cost		23	24
Expected return on assets		(26)	(26)
Prior service cost (credit)		2	2
Actuarial loss (gain)		6	4
Net periodic benefit cost (credit)		27	22
Regulatory adjustment		(26)	(5)
Total expense recognized		1	17
Contributions by employer		0
Expected contributions in current fiscal year		113
Other postretirement benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost		6	6
Interest cost		9	9
Expected return on assets		(18)	(16)
Prior service cost (credit)		0	0
Actuarial loss (gain)		(1)	(1)
Settlements		0	0
Net periodic benefit cost (credit)		(4)	(2)
Regulatory adjustment		4	2
Total expense recognized		0	0
Contributions by employer		1
Expected contributions in current fiscal year		9
Other postretirement benefits [Member] | San Diego Gas and Electric Company [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost		1	1
Interest cost		2	2
Expected return on assets		(3)	(3)
Prior service cost (credit)		1	1
Actuarial loss (gain)		(1)	0
Settlements		0	0
Net periodic benefit cost (credit)		0	1
Regulatory adjustment		0	(1)
Total expense recognized		0	0
Contributions by employer		0
Expected contributions in current fiscal year		3
Other postretirement benefits [Member] | Southern California Gas Company [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost		4	4
Interest cost		7	7
Expected return on assets		(14)	(13)
Prior service cost (credit)		(1)	(1)
Actuarial loss (gain)		0	0
Net periodic benefit cost (credit)		(4)	(3)
Regulatory adjustment		4	3
Total expense recognized		0	$ 0
Contributions by employer		1
Expected contributions in current fiscal year		$ 2
Oncor Holdings [Member] | Sempra Texas Holdings Corp [Member] | Sempra Texas Intermediate Holding Company LLC [Member]
Defined Benefit Plan Disclosure [Line Items]
Increase in liability due to acquisition	$ 21