GENERAL INFORMATION AND OTHER FINANCIAL DATA - OTHER (EXPENSE) INCOME, NET (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Other Income [Line Items]
Allowance for equity funds used during construction	$ 31	$ 21
Investment gains	(37)	26
(Losses) gains on interest rate and foreign exchange instruments, net	(153)	13
Foreign currency transaction gains (losses), net	(123)	7
Non-service component of net periodic benefit credit	26	24
Penalties related to billing practices OII	0	(8)
Interest on regulatory balancing accounts, net	2	(1)
Total	(254)	82
Foreign Currency Transaction Gain (Loss), before Tax	(123)	7
San Diego Gas and Electric Company [Member]
Other Income [Line Items]
Allowance for equity funds used during construction	21	12
Non-service component of net periodic benefit credit	8	9
Interest on regulatory balancing accounts, net	2	0
Sundry, net	0	1
Total	31	22
Southern California Gas Company [Member]
Other Income [Line Items]
Allowance for equity funds used during construction	8	8
Non-service component of net periodic benefit credit	25	18
Penalties related to billing practices OII	0	(8)
Interest on regulatory balancing accounts, net	0	(1)
Sundry, net	(3)	(1)
Total	30	16
Sempra Mexico [Member] | IMG [Member]
Other Income [Line Items]
Foreign Currency Transaction Gain (Loss), before Tax	$ (149)	$ 10