GENERAL INFORMATION AND OTHER FINANCIAL DATA - PENSION AND OTHER POSTRETIREMENT BENEFITS (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Amortization of:
Settlement charges	$ 5
Pension benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	33	$ 27
Interest cost	32	35
Expected return on assets	(42)	(36)
Amortization of:
Prior service cost (credit)	3	3
Actuarial loss (gain)	9	14
Settlement charges	5	0
Net periodic benefit cost (credit)	40	43
Regulatory adjustments	(28)	(36)
Total expense recognized	12	7
Contributions by employer	20
Expected contributions in current fiscal year	268
Pension benefits [Member] | San Diego Gas and Electric Company [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	8	8
Interest cost	7	9
Expected return on assets	(13)	(11)
Amortization of:
Prior service cost (credit)	1	1
Actuarial loss (gain)	1	4
Net periodic benefit cost (credit)	4	11
Regulatory adjustments	(3)	(11)
Total expense recognized	1	0
Contributions by employer	0
Expected contributions in current fiscal year	53
Pension benefits [Member] | Southern California Gas Company [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	22	16
Interest cost	22	23
Expected return on assets	(27)	(24)
Amortization of:
Prior service cost (credit)	2	2
Actuarial loss (gain)	6	9
Net periodic benefit cost (credit)	25	26
Regulatory adjustments	(25)	(25)
Total expense recognized	0	1
Contributions by employer	1
Expected contributions in current fiscal year	154
Other postretirement benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	5	4
Interest cost	8	9
Expected return on assets	(13)	(18)
Amortization of:
Prior service cost (credit)	(1)	0
Actuarial loss (gain)	(3)	(2)
Settlement charges	0	0
Net periodic benefit cost (credit)	(4)	(7)
Regulatory adjustments	4	7
Total expense recognized	0	0
Contributions by employer	1
Expected contributions in current fiscal year	7
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)
Amortization of:
Prior service cost (credit)	0	1
Actuarial loss (gain)	(1)	(1)
Net periodic benefit cost (credit)	(1)	0
Regulatory adjustments	1	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	3
Interest cost	6	7
Expected return on assets	(10)	(14)
Amortization of:
Prior service cost (credit)	0	(1)
Actuarial loss (gain)	(2)	(2)
Net periodic benefit cost (credit)	(3)	(7)
Regulatory adjustments	3	7
Total expense recognized	0	$ 0
Contributions by employer	0
Expected contributions in current fiscal year	$ 1