GENERAL INFORMATION AND OTHER FINANCIAL DATA - PENSION AND OTHER POSTRETIREMENT BENEFITS (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract]
Settlement charges		$ 4	$ 7	$ 9
Amortization of:
Settlement charges		4	7	9
Pension benefits [Member]
Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract]
Settlement charges	$ 0	4	7	9
Defined Benefit Plan Disclosure [Line Items]
Service cost	36	33	73	66
Interest cost	28	33	56	65
Expected return on assets	(43)	(43)	(86)	(85)
Amortization of:
Prior service cost (credit)	2	3	5	6
Actuarial loss (gain)	11	8	22	17
Settlement charges	0	4	7	9
Net periodic benefit cost (credit)	34	38	77	78
Regulatory adjustments	22	22	(7)	(6)
Total expense recognized	56	60	70	72
Pension benefits [Member] | San Diego Gas and Electric Company [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	9	8	17	16
Interest cost	6	8	12	15
Expected return on assets	(13)	(12)	(25)	(25)
Amortization of:
Prior service cost (credit)			0	1
Actuarial loss (gain)	1	1	1	2
Net periodic benefit cost (credit)	3	5	5	9
Regulatory adjustments	11	9	9	6
Total expense recognized	14	14	14	15
Pension benefits [Member] | Southern California Gas Company [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	25	22	50	44
Interest cost	20	22	40	44
Expected return on assets	(30)	(27)	(58)	(54)
Amortization of:
Prior service cost (credit)	2	2	4	4
Actuarial loss (gain)	10	7	19	13
Net periodic benefit cost (credit)	27	26	55	51
Regulatory adjustments	11	13	(16)	(12)
Total expense recognized	38	39	39	39
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	5	4	11	9
Interest cost	7	8	14	16
Expected return on assets	(15)	(14)	(30)	(27)
Amortization of:
Prior service cost (credit)	0	0	(1)	(1)
Actuarial loss (gain)	(2)	(2)	(4)	(5)
Settlement charges	0	0	0	0
Net periodic benefit cost (credit)	(5)	(4)	(10)	(8)
Regulatory adjustments	5	4	10	8
Total expense recognized	0	0	0	0
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	3	3
Expected return on assets	(3)	(2)	(5)	(5)
Amortization of:
Prior service cost (credit)			0	0
Actuarial loss (gain)	(1)	0	(1)	(1)
Net periodic benefit cost (credit)	(1)	0	(1)	(1)
Regulatory adjustments	1	0	1	1
Total expense recognized	0	0	0	0
Other postretirement benefits [Member] | Southern California Gas Company [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	4	4	8	7
Interest cost	6	6	11	12
Expected return on assets	(12)	(11)	(24)	(21)
Amortization of:
Prior service cost (credit)	0	(1)	(1)	(1)
Actuarial loss (gain)	(2)	(2)	(3)	(4)
Net periodic benefit cost (credit)	(4)	(4)	(9)	(7)
Regulatory adjustments	4	4	9	7
Total expense recognized	$ 0	$ 0	$ 0	$ 0