GENERAL INFORMATION AND OTHER FINANCIAL DATA - PENSION AND OTHER POSTRETIREMENT BENEFITS (Details) - USD ($) $ in Millions	1 Months Ended	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Pension benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Reduction in plan assets due to settlement					$ 274
Service cost		$ 28	$ 33	$ 55	66
Interest cost		35	34	70	69
Expected return on assets		(36)	(40)	(72)	(82)
Prior service cost (credit)		3	2	6	5
Actuarial loss (gain)		7	10	21	19
Settlement charges	$ 22	22	25	22	39
Net periodic benefit cost (credit)		59	64	102	116
Regulatory adjustments		3	(35)	(33)	(80)
Total expense recognized		62	29	69	36
Contributions by employer				93
Expected contributions in current fiscal year	234	234		234
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		7	8	15	16
Interest cost		8	8	17	17
Expected return on assets		(9)	(12)	(20)	(25)
Prior service cost (credit)		1	1	2	1
Actuarial loss (gain)		3	2	7	3
Settlement charges		0	2	0	16
Net periodic benefit cost (credit)		10	9	21	28
Regulatory adjustments		(1)	(8)	(12)	(27)
Total expense recognized		9	1	9	1
Contributions by employer				8
Expected contributions in current fiscal year	40	40		40
Pension benefits [Member] | Southern California Gas Company [Member]
Defined Benefit Plan Disclosure [Line Items]
Reduction in plan assets due to settlement					177
Service cost		18	21	34	43
Interest cost		22	22	45	45
Expected return on assets		(23)	(25)	(47)	(51)
Prior service cost (credit)		2	2	4	4
Actuarial loss (gain)		2	6	11	12
Settlement charges		0	23	0	23
Net periodic benefit cost (credit)		21	49	47	76
Regulatory adjustments		4	(27)	(21)	(53)
Total expense recognized		25	22	26	23
Contributions by employer				26
Expected contributions in current fiscal year	118	118		118
Other postretirement benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost		4	5	8	11
Interest cost		9	9	18	18
Expected return on assets		(17)	(17)	(35)	(35)
Prior service cost (credit)		0	0	0	0
Actuarial loss (gain)		(3)	(1)	(5)	(2)
Settlement charges		0	0	0	0
Net periodic benefit cost (credit)		(7)	(4)	(14)	(8)
Regulatory adjustments		7	5	14	9
Total expense recognized		0	1	0	1
Contributions by employer				5
Expected contributions in current fiscal year	8	8		8
Other postretirement benefits [Member] | San Diego Gas and Electric Company [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost		1	1	2	2
Interest cost		2	1	4	3
Expected return on assets		(3)	(4)	(6)	(7)
Prior service cost (credit)		0	1	1	2
Actuarial loss (gain)		0	0	(1)	(1)
Settlement charges		0	0	0	0
Net periodic benefit cost (credit)		0	(1)	0	(1)
Regulatory adjustments		0	1	0	1
Total expense recognized		0	0	0	0
Contributions by employer				0
Expected contributions in current fiscal year	0	0		0
Other postretirement benefits [Member] | Southern California Gas Company [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost		3	4	6	8
Interest cost		7	7	14	14
Expected return on assets		(15)	(14)	(29)	(28)
Prior service cost (credit)		0	0	(1)	(1)
Actuarial loss (gain)		(2)	(1)	(4)	(1)
Settlement charges		0	0	0	0
Net periodic benefit cost (credit)		(7)	(4)	(14)	(8)
Regulatory adjustments		7	4	14	8
Total expense recognized		0	$ 0	0	$ 0
Contributions by employer				0
Expected contributions in current fiscal year	$ 1	$ 1		$ 1