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, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract]
Settlement charges	$ 22	$ 4		$ 9
Amortization of:
Settlement charges	$ 22	4		9
Pension benefits [Member]
Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract]
Settlement charges		4	$ 22	9	$ 22
Defined Benefit Plan Disclosure [Line Items]
Service cost		33	28	66	55
Interest cost		33	35	65	70
Expected return on assets		(43)	(36)	(85)	(72)
Amortization of:
Prior service cost (credit)		3	3	6	6
Actuarial loss (gain)		8	7	17	21
Settlement charges		4	22	9	22
Net periodic benefit cost (credit)		38	59	78	102
Regulatory adjustments		22	3	(6)	(33)
Total expense recognized		60	62	72	69
Contributions by employer				82
Expected contributions in current fiscal year		268		268
Pension benefits [Member] | San Diego Gas and Electric Company [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost		8	7	16	15
Interest cost		8	8	15	17
Expected return on assets		(12)	(9)	(25)	(20)
Amortization of:
Prior service cost (credit)		0	1	1	2
Actuarial loss (gain)		1	3	2	7
Net periodic benefit cost (credit)		5	10	9	21
Regulatory adjustments		9	(1)	6	(12)
Total expense recognized		14	9	15	9
Contributions by employer				13
Expected contributions in current fiscal year		53		53
Pension benefits [Member] | Southern California Gas Company [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost		22	18	44	34
Interest cost		22	22	44	45
Expected return on assets		(27)	(23)	(54)	(47)
Amortization of:
Prior service cost (credit)		2	2	4	4
Actuarial loss (gain)		7	2	13	11
Net periodic benefit cost (credit)		26	21	51	47
Regulatory adjustments		13	4	(12)	(21)
Total expense recognized		39	25	39	26
Contributions by employer				38
Expected contributions in current fiscal year		154		154
Other postretirement benefits [Member]
Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract]
Settlement charges		0	0	0	0
Defined Benefit Plan Disclosure [Line Items]
Service cost		4	4	9	8
Interest cost		8	9	16	18
Expected return on assets		(14)	(17)	(27)	(35)
Amortization of:
Prior service cost (credit)		0	0	(1)	0
Actuarial loss (gain)		(2)	(3)	(5)	(5)
Settlement charges		0	0	0	0
Net periodic benefit cost (credit)		(4)	(7)	(8)	(14)
Regulatory adjustments		4	7	8	14
Total expense recognized		0	0	0	0
Contributions by employer				3
Expected contributions in current fiscal year		7		7
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		1	2	3	4
Expected return on assets		(2)	(3)	(5)	(6)
Amortization of:
Prior service cost (credit)		0	0	0	1
Actuarial loss (gain)		0	0	(1)	(1)
Net periodic benefit cost (credit)		0	0	(1)	0
Regulatory adjustments		0	0	1	0
Total expense recognized		0	0	0	0
Contributions by employer				0
Expected contributions in current fiscal year		0		0
Other postretirement benefits [Member] | Southern California Gas Company [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost		4	3	7	6
Interest cost		6	7	12	14
Expected return on assets		(11)	(15)	(21)	(29)
Amortization of:
Prior service cost (credit)		(1)	0	(1)	(1)
Actuarial loss (gain)		(2)	(2)	(4)	(4)
Net periodic benefit cost (credit)		(4)	(7)	(7)	(14)
Regulatory adjustments		4	7	7	14
Total expense recognized		0	$ 0	0	$ 0
Contributions by employer				0
Expected contributions in current fiscal year		$ 1		$ 1