GENERAL INFORMATION AND OTHER FINANCIAL DATA - PENSION AND OTHER POSTRETIREMENT BENEFITS (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Pension benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 27	$ 33
Interest cost	35	35
Expected return on assets	(36)	(42)
Prior service cost (credit)	3	3
Actuarial loss (gain)	14	9
Settlement charges	0	14
Net periodic benefit cost (credit)	43	52
Regulatory adjustment	(36)	(45)
Total expense recognized	7	7
Contributions by employer	9
Expected contributions in current fiscal year	234
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	(11)	(13)
Prior service cost (credit)	1	0
Actuarial loss (gain)	4	1
Settlement charges	0	14
Net periodic benefit cost (credit)	11	19
Regulatory adjustment	(11)	(19)
Total expense recognized	0	0
Contributions by employer	0
Expected contributions in current fiscal year	40
Pension benefits [Member] | Southern California Gas Company [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	16	22
Interest cost	23	23
Expected return on assets	(24)	(26)
Prior service cost (credit)	2	2
Actuarial loss (gain)	9	6
Net periodic benefit cost (credit)	26	27
Regulatory adjustment	(25)	(26)
Total expense recognized	1	1
Contributions by employer	1
Expected contributions in current fiscal year	118
Other postretirement benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	4	6
Interest cost	9	9
Expected return on assets	(18)	(18)
Prior service cost (credit)	0	0
Actuarial loss (gain)	(2)	(1)
Settlement charges	0	0
Net periodic benefit cost (credit)	(7)	(4)
Regulatory adjustment	7	4
Total expense recognized	0	0
Contributions by employer	2
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)	(1)
Settlement charges	0	0
Net periodic benefit cost (credit)	0	0
Regulatory adjustment	0	0
Total expense recognized	0	0
Contributions by employer	0
Expected contributions in current fiscal year	0
Other postretirement benefits [Member] | Southern California Gas Company [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	3	4
Interest cost	7	7
Expected return on assets	(14)	(14)
Prior service cost (credit)	(1)	(1)
Actuarial loss (gain)	(2)	0
Net periodic benefit cost (credit)	(7)	(4)
Regulatory adjustment	7	4
Total expense recognized	0	$ 0
Contributions by employer	0
Expected contributions in current fiscal year	$ 1