OTHER FINANCIAL DATA - PENSION AND OTHER POSTRETIREMENT BENEFITS (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Pension Benefits
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 28	$ 30
Interest cost	40	39
Expected return on assets	(42)	(44)
Amortization of prior service cost	3	3
Amortization of actuarial loss	6	8
Regulatory adjustment	(28)	(29)
Total net periodic benefit cost	7	7
Defined benefit plan, contributions by employer	15
Defined benefit plan, expected contributions in current fiscal year	123
Pension Benefits | San Diego Gas and Electric Company [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	7	8
Interest cost	10	10
Expected return on assets	(12)	(14)
Amortization of prior service cost	0	0
Amortization of actuarial loss	3	2
Regulatory adjustment	(7)	(5)
Total net periodic benefit cost	1	1
Defined benefit plan, contributions by employer	2
Defined benefit plan, expected contributions in current fiscal year	4
Pension Benefits | Southern California Gas Company [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	17	19
Interest cost	25	25
Expected return on assets	(25)	(27)
Amortization of prior service cost	2	2
Amortization of actuarial loss	3	5
Regulatory adjustment	(21)	(24)
Total net periodic benefit cost	1	0
Defined benefit plan, contributions by employer	0
Defined benefit plan, expected contributions in current fiscal year	77
Other Postretirement Benefits
Defined Benefit Plan Disclosure [Line Items]
Service cost	5	7
Interest cost	11	12
Expected return on assets	(17)	(17)
Amortization of prior service cost	0	(1)
Amortization of actuarial loss	0	0
Regulatory adjustment	2	0
Total net periodic benefit cost	1	1
Defined benefit plan, contributions by employer	1
Defined benefit plan, expected contributions in current fiscal year	6
Other Postretirement Benefits | San Diego Gas and Electric Company [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	1	2
Interest cost	2	2
Expected return on assets	(3)	(3)
Amortization of prior service cost	1	1
Amortization of actuarial loss	0	0
Regulatory adjustment	(1)	(2)
Total net periodic benefit cost	0	0
Defined benefit plan, contributions by employer	0
Defined benefit plan, expected contributions in current fiscal year	2
Other Postretirement Benefits | Southern California Gas Company [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	4	5
Interest cost	8	9
Expected return on assets	(14)	(14)
Amortization of prior service cost	(1)	(2)
Amortization of actuarial loss	0	0
Regulatory adjustment	3	2
Total net periodic benefit cost	0	$ 0
Defined benefit plan, contributions by employer	0
Defined benefit plan, expected contributions in current fiscal year	$ 1