GENERAL INFORMATION AND OTHER FINANCIAL DATA - OTHER (EXPENSE) INCOME, NET (Details) - USD ($) $ in Millions	1 Months Ended	3 Months Ended		9 Months Ended
	Jan. 31, 2019	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Other Income [Line Items]
Allowance for equity funds used during construction		$ 25	$ 23	$ 69	$ 79
Investment gains		9	8	46	13
(Losses) gains on interest rate and foreign exchange instruments, net		(17)	39	7	46
Foreign currency transaction gains (losses), net		(13)	28	(2)	16
Non-service component of net periodic benefit (cost) credit		(13)	(3)	(19)	37
Penalties related to billing practices OII		0	0	(8)	0
Interest on regulatory balancing accounts, net		4	1	9	2
Sundry, net		(2)	0	1	(1)
Total		(7)	96	103	192
San Diego Gas and Electric Company [Member]
Other Income [Line Items]
Allowance for equity funds used during construction		15	15	42	49
Non-service component of net periodic benefit (cost) credit		0	8	8	25
Interest on regulatory balancing accounts, net		4	2	10	4
Sundry, net		0	(1)	0	(1)
Total		19	24	60	77
Southern California Gas Company [Member]
Other Income [Line Items]
Allowance for equity funds used during construction		9	8	25	30
Non-service component of net periodic benefit (cost) credit		(5)	(1)	9	27
Penalties related to billing practices OII	$ (8)	0	0	(8)	0
Interest on regulatory balancing accounts, net		0	(1)	(1)	(2)
Sundry, net		(3)	(3)	(7)	(6)
Total		1	3	18	49
Sempra Mexico [Member] | IMG [Member]
Other Income [Line Items]
Foreign Currency Transaction Gain, before Tax			$ 33		$ 25
Foreign Currency Transaction Loss, before Tax		$ 17		$ 0