GENERAL INFORMATION AND OTHER FINANCIAL DATA - OTHER (EXPENSE) INCOME, NET (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Other Income [Line Items]
Allowance for equity funds used during construction	$ 31	$ 23	$ 62	$ 44
Investment gains (losses)	30	11	(7)	37
Gains (losses) on interest rate and foreign exchange instruments, net	5	11	(148)	24
Foreign currency transaction gains (losses), net	13	4	(110)	11
Non-service component of net periodic benefit (cost) credit	(23)	(30)	3	(6)
Penalties related to billing practices OII	0	0	0	(8)
Interest on regulatory balancing accounts, net	11	6	13	5
Sundry, net	(5)	3	(5)	3
Total	62	28	(192)	110
Foreign currency translation gain (loss)			(110)	11
San Diego Gas and Electric Company [Member]
Other Income [Line Items]
Allowance for equity funds used during construction	19	15	40	27
Non-service component of net periodic benefit (cost) credit	(5)	(1)	3	8
Interest on regulatory balancing accounts, net	6	6	8	6
Sundry, net	(2)	(1)	(2)	0
Total	18	19	49	41
Southern California Gas Company [Member]
Other Income [Line Items]
Allowance for equity funds used during construction	10	8	18	16
Non-service component of net periodic benefit (cost) credit	(13)	(4)	12	14
Penalties related to billing practices OII	0	0	0	(8)
Interest on regulatory balancing accounts, net	5	0	5	(1)
Sundry, net	(4)	(3)	(7)	(4)
Total	(2)	1	28	17
Sempra Mexico [Member] | IMG [Member]
Other Income [Line Items]
Foreign currency translation gain (loss)	$ 14	$ 7	$ (135)	$ 17