GENERAL INFORMATION AND OTHER FINANCIAL DATA - OTHER INCOME (EXPENSE), NET (Details) - USD ($) $ in Millions	1 Months Ended	3 Months Ended
	Jan. 31, 2019	Mar. 31, 2019	Mar. 31, 2018
Other Income [Line Items]
Allowance for equity funds used during construction		$ 21	$ 27
Investment gains (losses)		26	(1)
Gains on interest rate and foreign exchange instruments, net		13	62
Foreign currency transaction gains, net		7	30
Non-service component of net periodic benefit credit		24	32
Penalties related to billing practices OII		(8)	0
Interest on regulatory balancing accounts, net		(1)	0
Sundry, net		0	2
Total		82	152
San Diego Gas and Electric Company [Member]
Other Income [Line Items]
Allowance for equity funds used during construction		12	18
Non-service component of net periodic benefit credit		9	9
Sundry, net		1	1
Total		22	28
Southern California Gas Company [Member]
Other Income [Line Items]
Allowance for equity funds used during construction		8	9
Non-service component of net periodic benefit credit		18	25
Penalties related to billing practices OII	$ (8)	(8)	0
Interest on regulatory balancing accounts, net		(1)	0
Sundry, net		(1)	(1)
Total		16	33
Sempra Mexico [Member] | IMG [Member]
Other Income [Line Items]
Foreign currency gain		$ 10	$ 39