GENERAL INFORMATION AND OTHER FINANCIAL DATA - PENSION AND OTHER POSTRETIREMENT BENEFITS (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract]
Settlement charges	$ 13		$ 22	$ 22
Amortization of:
Settlement charges	13		22	22
Pension benefits [Member]
Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract]
Settlement charges	13	$ 4	22	26
Defined Benefit Plan Disclosure [Line Items]
Service cost	31	27	97	82
Interest cost	32	34	97	104
Expected return on assets	(41)	(36)	(126)	(108)
Amortization of:
Prior service cost (credit)	3	3	9	9
Actuarial loss (gain)	9	8	26	29
Settlement charges	13	4	22	26
Net periodic benefit cost (credit)	47	40	125	142
Regulatory adjustments	37	3	31	(30)
Total expense recognized	84	43	156	112
Contributions by employer			202
Expected contributions in current fiscal year	298		298
Pension benefits [Member] | San Diego Gas and Electric Company [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	7	7	23	22
Interest cost	7	9	22	26
Expected return on assets	(12)	(9)	(37)	(29)
Amortization of:
Prior service cost (credit)	1	0	2	2
Actuarial loss (gain)	1	2	3	9
Net periodic benefit cost (credit)	4	9	13	30
Regulatory adjustments	22	(1)	28	(13)
Total expense recognized	26	8	41	17
Contributions by employer			39
Expected contributions in current fiscal year	54		54
Pension benefits [Member] | Southern California Gas Company [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	20	17	64	51
Interest cost	22	23	66	68
Expected return on assets	(27)	(24)	(81)	(71)
Amortization of:
Prior service cost (credit)	2	2	6	6
Actuarial loss (gain)	6	3	19	14
Net periodic benefit cost (credit)	23	21	74	68
Regulatory adjustments	15	4	3	(17)
Total expense recognized	38	25	77	51
Contributions by employer			76
Expected contributions in current fiscal year	155		155
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	14	12
Interest cost	8	9	24	27
Expected return on assets	(14)	(17)	(41)	(52)
Amortization of:
Prior service cost (credit)	(1)	0	(2)	0
Actuarial loss (gain)	(2)	(3)	(7)	(8)
Settlement charges	0	0	0	0
Net periodic benefit cost (credit)	(4)	(7)	(12)	(21)
Regulatory adjustments	4	8	12	22
Total expense recognized	0	1	0	1
Contributions by employer			6
Expected contributions in current fiscal year	8		8
Other postretirement benefits [Member] | San Diego Gas and Electric Company [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	1	1	3	3
Interest cost	2	1	5	5
Expected return on assets	(3)	(3)	(8)	(9)
Amortization of:
Prior service cost (credit)	0	1	0	2
Actuarial loss (gain)	(1)	0	(2)	(1)
Net periodic benefit cost (credit)	(1)	0	(2)	0
Regulatory adjustments	1	0	2	0
Total expense recognized	0	0	0	0
Contributions by employer			1
Expected contributions in current fiscal year	1		1
Other postretirement benefits [Member] | Southern California Gas Company [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	3	3	10	9
Interest cost	7	6	19	20
Expected return on assets	(11)	(14)	(32)	(43)
Amortization of:
Prior service cost (credit)	(1)	(1)	(2)	(2)
Actuarial loss (gain)	(1)	(2)	(5)	(6)
Net periodic benefit cost (credit)	(3)	(8)	(10)	(22)
Regulatory adjustments	3	8	10	22
Total expense recognized	0	$ 0	0	$ 0
Contributions by employer			1
Expected contributions in current fiscal year	$ 1		$ 1