GENERAL INFORMATION AND OTHER FINANCIAL DATA - OTHER INCOME (EXPENSE), NET (Details) - USD ($) $ in Millions	1 Months Ended	3 Months Ended		6 Months Ended
	Jan. 31, 2019	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Other Income [Line Items]
Allowance for equity funds used during construction		$ 23	$ 29	$ 44	$ 56
Investment gains		11	6	37	5
Gains (losses) on interest rate and foreign exchange instruments, net		11	(55)	24	7
Foreign currency transaction gains (losses), net		4	(42)	11	(12)
Non-service component of net periodic benefit (cost) credit		(30)	8	(6)	40
Penalties related to billing practices OII		0	0	(8)	0
Interest on regulatory balancing accounts, net		6	1	5	1
Sundry, net		3	(3)	3	(1)
Total		28	(56)	110	96
San Diego Gas and Electric Company [Member]
Other Income [Line Items]
Allowance for equity funds used during construction		15	16	27	34
Non-service component of net periodic benefit (cost) credit		(1)	8	8	17
Interest on regulatory balancing accounts, net		6	2	6	2
Sundry, net		(1)	(1)	0	0
Total		19	25	41	53
Southern California Gas Company [Member]
Other Income [Line Items]
Allowance for equity funds used during construction		8	13	16	22
Non-service component of net periodic benefit (cost) credit		(4)	3	14	28
Penalties related to billing practices OII	$ (8)	0	0	(8)	0
Interest on regulatory balancing accounts, net		0	(1)	(1)	(1)
Sundry, net		(3)	(2)	(4)	(3)
Total		1	13	17	46
Sempra Mexico [Member] | IMG [Member]
Other Income [Line Items]
Foreign currency gain		$ 7		$ 17
Foreign Currency Transaction Loss, before Tax			$ 47		$ 8