OTHER FINANCIAL DATA - PENSION AND OTHER POSTRETIREMENT BENEFITS (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Pension Benefits
Net Periodic Benefit Cost
Service cost	$ 27	$ 23	$ 86	$ 75
Interest cost	38	39	116	121
Expected return on assets	(42)	(42)	(130)	(128)
Amortization of prior service cost	3	3	8	8
Amortization of actuarial loss	9	3	28	13
Settlement	4	5	4	14
Regulatory adjustment	(27)	6	(86)	(18)
Total net periodic benefit cost	12	37	26	85
Pension and Other Postretirement Benefit Contributions [Abstract]
Contributions to pension plans			27
Expected contributions to benefit plans			36
Pension Benefits | San Diego Gas and Electric Company [Member]
Net Periodic Benefit Cost
Service cost	6	8	22	23
Interest cost	9	10	29	32
Expected return on assets	(14)	(13)	(41)	(41)
Amortization of prior service cost			1	1
Amortization of actuarial loss	3	1	7	3
Settlement	0	0	0	2
Regulatory adjustment	(3)	6	(15)	7
Total net periodic benefit cost	1	12	3	27
Pension and Other Postretirement Benefit Contributions [Abstract]
Contributions to pension plans			2
Expected contributions to benefit plans			3
Pension Benefits | Southern California Gas Company [Member]
Net Periodic Benefit Cost
Service cost	17	13	55	45
Interest cost	25	24	74	75
Expected return on assets	(25)	(26)	(79)	(78)
Amortization of prior service cost	2	2	6	6
Amortization of actuarial loss	5	1	16	5
Settlement	0	4	0	4
Regulatory adjustment	(24)	0	(71)	(25)
Total net periodic benefit cost	0	18	1	32
Pension and Other Postretirement Benefit Contributions [Abstract]
Contributions to pension plans			1
Expected contributions to benefit plans			7
Other Postretirement Benefits
Net Periodic Benefit Cost
Service cost	5	6	19	18
Interest cost	10	13	33	37
Expected return on assets	(17)	(15)	(51)	(47)
Amortization of prior service cost	(1)	(2)	(2)	(4)
Amortization of actuarial loss	0	0	0	0
Settlement	0	5	0	5
Regulatory adjustment	4	5	4	5
Total net periodic benefit cost	1	12	3	14
Pension and Other Postretirement Benefit Contributions [Abstract]
Contributions to other postretirement benefit plans			3
Expected contributions to benefit plans			11
Other Postretirement Benefits | San Diego Gas and Electric Company [Member]
Net Periodic Benefit Cost
Service cost	1	2	5	5
Interest cost	2	3	6	7
Expected return on assets	(2)	(2)	(8)	(8)
Amortization of prior service cost			2	2
Amortization of actuarial loss	0	0	0	0
Settlement	0	5	0	5
Regulatory adjustment	(1)	4	(5)	1
Total net periodic benefit cost	0	12	0	12
Pension and Other Postretirement Benefit Contributions [Abstract]
Contributions to other postretirement benefit plans			0
Expected contributions to benefit plans			7
Other Postretirement Benefits | Southern California Gas Company [Member]
Net Periodic Benefit Cost
Service cost	3	4	13	12
Interest cost	8	9	26	28
Expected return on assets	(14)	(12)	(42)	(38)
Amortization of prior service cost	(2)	(2)	(6)	(6)
Amortization of actuarial loss	0	0	0	0
Settlement	0	0	0	0
Regulatory adjustment	5	1	9	4
Total net periodic benefit cost	$ 0	$ 0	0	$ 0
Pension and Other Postretirement Benefit Contributions [Abstract]
Contributions to other postretirement benefit plans			0
Expected contributions to benefit plans			$ 1