OTHER FINANCIAL DATA - PENSION AND OTHER POSTRETIREMENT BENEFITS (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Pension benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 26	$ 27	$ 81	$ 86
Interest cost	40	38	120	116
Expected return on assets	(41)	(42)	(124)	(130)
Amortization of prior service cost (credit)	2	3	8	8
Amortization of actuarial loss (gain)	10	9	23	28
Settlements	0	4	0	4
Regulatory adjustment	(28)	(27)	(84)	(86)
Total net periodic benefit cost	9	12	24	26
Contributions by employer			24
Expected contributions in current fiscal year			124
Pension benefits [Member] | San Diego Gas and Electric Company [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	7	6	22	22
Interest cost	10	9	31	29
Expected return on assets	(12)	(14)	(37)	(41)
Amortization of prior service cost (credit)			1	1
Amortization of actuarial loss (gain)	2	3	7	7
Regulatory adjustment	(7)	(3)	(22)	(15)
Total net periodic benefit cost	0	1	2	3
Contributions by employer			2
Expected contributions in current fiscal year			7
Pension benefits [Member] | Southern California Gas Company [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	16	17	51	55
Interest cost	26	25	76	74
Expected return on assets	(26)	(25)	(78)	(79)
Amortization of prior service cost (credit)	3	2	7	6
Amortization of actuarial loss (gain)	3	5	8	16
Regulatory adjustment	(21)	(24)	(62)	(71)
Total net periodic benefit cost	1	0	2	1
Contributions by employer			1
Expected contributions in current fiscal year			73
Other postretirement benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	4	5	15	19
Interest cost	9	10	31	33
Expected return on assets	(17)	(17)	(52)	(51)
Amortization of prior service cost (credit)	0	(1)	0	(2)
Amortization of actuarial loss (gain)	(1)	0	(1)	0
Settlements	0	0	0	0
Regulatory adjustment	5	4	9	4
Total net periodic benefit cost	0	1	2	3
Contributions by employer			3
Expected contributions in current fiscal year			6
Other postretirement benefits [Member] | San Diego Gas and Electric Company [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	1	1	3	5
Interest cost	2	2	6	6
Expected return on assets	(3)	(2)	(8)	(8)
Amortization of prior service cost (credit)			2	2
Amortization of actuarial loss (gain)	0	0	(1)	0
Regulatory adjustment	0	(1)	(2)	(5)
Total net periodic benefit cost	0	0	0	0
Contributions by employer			0
Expected contributions in current fiscal year			2
Other postretirement benefits [Member] | Southern California Gas Company [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	4	3	11	13
Interest cost	7	8	24	26
Expected return on assets	(15)	(14)	(43)	(42)
Amortization of prior service cost (credit)	(1)	(2)	(3)	(6)
Amortization of actuarial loss (gain)	0	0	0	0
Regulatory adjustment	5	5	11	9
Total net periodic benefit cost	$ 0	$ 0	0	$ 0
Contributions by employer			1
Expected contributions in current fiscal year			$ 1