GENERAL INFORMATION AND OTHER FINANCIAL DATA - OTHER (EXPENSE) INCOME, NET (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Other Income [Line Items]
Allowance for equity funds used during construction	$ 34	$ 31	$ 72	$ 62
Investment gains	19	30	28	(7)
Gains (losses) on interest rate and foreign exchange instruments, net	7	5	(23)	(148)
Foreign currency transaction gains (losses), net(2)	26	13	7	(110)
Non-service component of net periodic benefit (cost) credit	(15)	(23)	14	3
Interest on regulatory balancing accounts, net	2	11	3	13
Sundry, net	(1)	(5)	6	(5)
Total	72	62	107	(192)
San Diego Gas and Electric Company [Member]
Other Income [Line Items]
Allowance for equity funds used during construction	22	19	45	40
Non-service component of net periodic benefit (cost) credit	(4)	(5)	5	3
Interest on regulatory balancing accounts, net	2	6	3	8
Sundry, net	2	(2)	4	(2)
Total	22	18	57	49
Southern California Gas Company [Member]
Other Income [Line Items]
Allowance for equity funds used during construction	11	10	23	18
Non-service component of net periodic benefit (cost) credit	(9)	(13)	19	12
Interest on regulatory balancing accounts, net	0	5	0	5
Sundry, net	(4)	(4)	(5)	(7)
Total	(2)	(2)	37	28
Sempra Mexico [Member] | IMG [Member]
Other Income [Line Items]
Foreign currency transaction gains (losses), net(2)	$ 28	$ 14	$ 5	$ (135)