INCOME TAXES - COMPONENTS OF INCOME TAX EXPENSE (BENEFIT) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Current Income Tax Expense (Benefit), Continuing Operations [Abstract]
U.S. federal	$ 0	$ 0	$ 3
U.S. state	0	1	(24)
Non-U.S.	116	171	123
Total	116	172	102
Deferred Income Tax Expense (Benefit), Continuing Operations [Abstract]
U.S. federal	536	78	242
U.S. state	297	9	34
Non-U.S.	327	135	(32)
Total	1,160	222	244
Deferred investment tax credits	0	(5)	(5)
Total income tax expense	1,276	389	341
San Diego Gas and Electric Company [Member]
Current Income Tax Expense (Benefit), Continuing Operations [Abstract]
U.S. federal	100	0	12
U.S. state	65	22	77
Total	165	22	89
Deferred Income Tax Expense (Benefit), Continuing Operations [Abstract]
U.S. federal	29	223	233
U.S. state	(41)	38	(35)
Total	(12)	261	198
Deferred investment tax credits	2	(3)	(3)
Total income tax expense	155	280	284
Southern California Gas Company [Member]
Current Income Tax Expense (Benefit), Continuing Operations [Abstract]
U.S. federal	0	0	(1)
U.S. state	23	40	12
Total	23	40	11
Deferred Income Tax Expense (Benefit), Continuing Operations [Abstract]
U.S. federal	144	123	122
U.S. state	(5)	(18)	7
Total	139	105	129
Deferred investment tax credits	(2)	(2)	(2)
Total income tax expense	$ 160	$ 143	$ 138