GENERAL INFORMATION AND OTHER FINANCIAL DATA - OTHER INCOME (EXPENSE), NET (Details) - USD ($) $ in Millions	3 Months Ended			9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017		Sep. 30, 2018	Sep. 30, 2017
Other Income [Line Items]
Allowance for equity funds used during construction	$ 23	$ 27		$ 79	$ 139
Investment gains	8	13		13	43
Gains on interest rate and foreign exchange instruments, net	39	5		46	99
Foreign currency transaction gains, net	28	(10)		17	7
Non-service component of net periodic benefit (cost) credit	(4)	(1)		35	21
Interest on regulatory balancing accounts, net	1	1		2	3
Sundry, net	2	5		4	10
Total	97	40	[1]	196	322	[1]
San Diego Gas and Electric Company [Member]
Other Income [Line Items]
Allowance for equity funds used during construction	15	15		49	46
Non-service component of net periodic benefit (cost) credit	8	4		25	12
Interest on regulatory balancing accounts, net	2	1		4	3
Sundry, net	(1)	0		(1)	0
Total	24	20	[1]	77	61	[1]
Southern California Gas Company [Member]
Other Income [Line Items]
Allowance for equity funds used during construction	8	11		30	33
Non-service component of net periodic benefit (cost) credit	(1)	5		27	23
Interest on regulatory balancing accounts, net	(1)	0		(2)	0
Sundry, net	(3)	(3)		(6)	(5)
Total	3	13	[1]	49	51	[1]
Sempra Mexico [Member] | IMG [Member]
Other Income [Line Items]
Foreign currency loss		$ 6			$ 0
Foreign currency gain	$ 33			$ 25

[1] As adjusted for the retrospective adoption of ASU 2017-07, which we discuss in Note 2, and a reclassification to conform to current year presentation, which we discuss in Note 1.