GENERAL INFORMATION AND OTHER FINANCIAL DATA - PENSION AND OTHER POSTRETIREMENT BENEFITS (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Pension benefits
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 41	$ 37
Interest cost	30	28
Expected return on assets	(46)	(43)
Amortization of:
Prior service cost (credit)	3	3
Actuarial loss (gain)	6	11
Settlement charges	0	7
Net periodic benefit cost (credit)	34	43
Regulatory adjustments	(27)	(29)
Total expense recognized	7	14
Pension benefits | San Diego Gas and Electric Company
Defined Benefit Plan Disclosure [Line Items]
Service cost	10	8
Interest cost	7	6
Expected return on assets	(11)	(12)
Amortization of:
Actuarial loss (gain)	0	0
Net periodic benefit cost (credit)	6	2
Regulatory adjustments	(5)	(2)
Total expense recognized	1	0
Pension benefits | Southern California Gas Company
Defined Benefit Plan Disclosure [Line Items]
Service cost	28	25
Interest cost	20	20
Expected return on assets	(31)	(28)
Amortization of:
Prior service cost (credit)	2	2
Actuarial loss (gain)	4	9
Net periodic benefit cost (credit)	23	28
Regulatory adjustments	(22)	(27)
Total expense recognized	1	1
Other postretirement benefits
Defined Benefit Plan Disclosure [Line Items]
Service cost	7	6
Interest cost	7	7
Expected return on assets	(16)	(15)
Amortization of:
Prior service cost (credit)	(1)	(1)
Actuarial loss (gain)	(4)	(2)
Settlement charges	0	0
Net periodic benefit cost (credit)	(7)	(5)
Regulatory adjustments	7	5
Total expense recognized	0	0
Other postretirement benefits | San Diego Gas and Electric Company
Defined Benefit Plan Disclosure [Line Items]
Service cost	2	1
Interest cost	1	1
Expected return on assets	(2)	(2)
Amortization of:
Actuarial loss (gain)	(1)	0
Net periodic benefit cost (credit)	0	0
Regulatory adjustments	0	0
Total expense recognized	0	0
Other postretirement benefits | Southern California Gas Company
Defined Benefit Plan Disclosure [Line Items]
Service cost	5	4
Interest cost	5	5
Expected return on assets	(13)	(12)
Amortization of:
Prior service cost (credit)	(1)	(1)
Actuarial loss (gain)	(3)	(1)
Net periodic benefit cost (credit)	(7)	(5)
Regulatory adjustments	7	5
Total expense recognized	$ 0	$ 0