GENERAL INFORMATION AND OTHER FINANCIAL DATA - OTHER (EXPENSE) INCOME, NET (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Other Income [Line Items]
Allowance for equity funds used during construction	$ 31	$ 34	$ 103	$ 96
Investment gains	0	16	28	9
(Losses) gains on interest rate and foreign exchange instruments, net	(3)	19	(26)	(129)
Foreign currency transaction (losses) gains, net(2)	(17)	15	(10)	(95)
Non-service component of net periodic benefit cost	(66)	(48)	(52)	(45)
Fine related to Energy Efficiency Program inquiry	0	(6)	0	(6)
Interest on regulatory balancing accounts, net	2	0	5	13
Sundry, net	(2)	(1)	4	(6)
Total	(55)	29	52	(163)
San Diego Gas and Electric Company [Member]
Other Income [Line Items]
Allowance for equity funds used during construction	18	21	63	61
Non-service component of net periodic benefit cost	(15)	(18)	(10)	(15)
Fine related to Energy Efficiency Program inquiry	0	(6)	0	(6)
Interest on regulatory balancing accounts, net	2	0	5	8
Sundry, net	(1)	1	3	(1)
Total	4	(2)	61	47
Southern California Gas Company [Member]
Other Income [Line Items]
Allowance for equity funds used during construction	13	11	36	29
Non-service component of net periodic benefit cost	(49)	(15)	(30)	(3)
Interest on regulatory balancing accounts, net	0	0	0	5
Sundry, net	(3)	(3)	(8)	(10)
Total	(39)	(7)	(2)	21
Sempra Mexico [Member] | IMG [Member]
Other Income [Line Items]
Foreign currency transaction (losses) gains, net(2)	$ (18)	$ 15	$ (13)	$ (120)