SIGNIFICANT ACCOUNTING POLICIES AND OTHER FINANCIAL DATA - OTHER INCOME, NET (Details) - USD ($) $ in Millions	1 Months Ended	12 Months Ended
	Jan. 31, 2019	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Other Income [Line Items]
Allowance for equity funds used during construction		$ 94	$ 98	$ 168
Investment (losses) gains		61	(6)	56
Gains on interest rate and foreign exchange instruments, net		34	7	47
Foreign currency transaction gains (losses)		21	(6)	(33)
Non-service component of net periodic benefit cost		(132)	(35)	(20)
Penalties related to billing practices OII		(8)	0	0
Interest on regulatory balancing accounts, net		14	2	3
Sundry, net		(7)	(2)	(1)
Total		77	58	220
San Diego Gas and Electric Company [Member]
Other Income [Line Items]
Allowance for equity funds used during construction		56	61	63
Non-service component of net periodic benefit cost		(20)	(6)	4
Interest on regulatory balancing accounts, net		13	4	3
Sundry, net		(10)	(3)	0
Total		39	56	70
Southern California Gas Company [Member]
Other Income [Line Items]
Allowance for equity funds used during construction		34	36	44
Non-service component of net periodic benefit cost		(72)	(10)	(5)
Penalties related to billing practices OII	$ (8)	(8)	0	0
Interest on regulatory balancing accounts, net		1	(2)	0
Sundry, net		(10)	(9)	(8)
Total		(55)	15	31
Sempra Mexico [Member] | IMG [Member]
Other Income [Line Items]
Foreign currency transaction gains (losses)		$ 30	$ (3)	$ (35)