GENERAL INFORMATION AND OTHER FINANCIAL DATA - PENSION AND OTHER POSTRETIREMENT BENEFITS (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Pension benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 27	$ 29	$ 82	$ 95
Interest cost	34	35	104	104
Expected return on assets	(36)	(35)	(108)	(117)
Amortization of:
Prior service cost (credit)	3	3	9	8
Actuarial loss (gain)	8	6	29	25
Settlement charges	4	9	26	48
Special termination benefits	0	0	0	0
Net periodic benefit cost (credit)	40	47	142	163
Regulatory adjustments	3	(11)	(30)	(91)
Total expense recognized	43	36	112	72
Contributions by employer			130
Expected contributions in current fiscal year	280		280
Pension benefits [Member] | San Diego Gas and Electric Company [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	7	7	22	23
Interest cost	9	9	26	26
Expected return on assets	(9)	(10)	(29)	(35)
Amortization of:
Prior service cost (credit)	0	0	2	1
Actuarial loss (gain)	2	0	9	3
Settlement charges	0	1	0	17
Special termination benefits	0	0	0	0
Net periodic benefit cost (credit)	9	7	30	35
Regulatory adjustments	(1)	(7)	(13)	(34)
Total expense recognized	8	0	17	1
Contributions by employer			17
Expected contributions in current fiscal year	53		53
Pension benefits [Member] | Southern California Gas Company [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	17	19	51	62
Interest cost	23	23	68	68
Expected return on assets	(24)	(22)	(71)	(73)
Amortization of:
Prior service cost (credit)	2	2	6	6
Actuarial loss (gain)	3	3	14	15
Settlement charges	0	2	0	25
Special termination benefits	0	0	0	0
Net periodic benefit cost (credit)	21	27	68	103
Regulatory adjustments	4	(4)	(17)	(57)
Total expense recognized	25	23	51	46
Contributions by employer			51
Expected contributions in current fiscal year	152		152
Other postretirement benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	4	4	12	15
Interest cost	9	9	27	27
Expected return on assets	(17)	(18)	(52)	(53)
Amortization of:
Prior service cost (credit)	0	0	0	0
Actuarial loss (gain)	(3)	(2)	(8)	(4)
Settlement charges	0	0	0	0
Special termination benefits	0	5	0	5
Net periodic benefit cost (credit)	(7)	(2)	(21)	(10)
Regulatory adjustments	8	2	22	11
Total expense recognized	1	0	1	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	1	2	5	5
Expected return on assets	(3)	(3)	(9)	(10)
Amortization of:
Prior service cost (credit)	1	0	2	2
Actuarial loss (gain)	0	(1)	(1)	(2)
Settlement charges	0	0	0	0
Special termination benefits	0	3	0	3
Net periodic benefit cost (credit)	0	2	0	1
Regulatory adjustments	0	(2)	0	(1)
Total expense recognized	0	0	0	0
Contributions by employer			0
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	9	11
Interest cost	6	6	20	20
Expected return on assets	(14)	(13)	(43)	(41)
Amortization of:
Prior service cost (credit)	(1)	(1)	(2)	(2)
Actuarial loss (gain)	(2)	(1)	(6)	(2)
Settlement charges	0	0	0	0
Special termination benefits	0	2	0	2
Net periodic benefit cost (credit)	(8)	(4)	(22)	(12)
Regulatory adjustments	8	4	22	12
Total expense recognized	0	0	0	0
Contributions by employer			1
Expected contributions in current fiscal year	$ 1		1
Nonqualified Plan [Member] | Pension benefits [Member]
Amortization of:
Settlement charges			$ 22
Qualified Plan [Member] | Pension benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Reduction in plan assets due to settlement				300
Amortization of:
Settlement charges		3		42
Qualified Plan [Member] | Pension benefits [Member] | San Diego Gas and Electric Company [Member]
Defined Benefit Plan Disclosure [Line Items]
Reduction in plan assets due to settlement				108
Amortization of:
Settlement charges		1		17
Qualified Plan [Member] | Pension benefits [Member] | Southern California Gas Company [Member]
Defined Benefit Plan Disclosure [Line Items]
Reduction in plan assets due to settlement				192
Amortization of:
Settlement charges		$ 2		$ 25