INCOME TAXES - CHANGES IN UNRECOGNIZED TAX BENEFITS (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2020	Dec. 31, 2019
Significant Change in Unrecognized Tax Benefits is Reasonably Possible [Line Items]
Possible change in unrecognized tax benefits in next 12 months	$ (41)	$ (8)	$ (8)
Accrual for interest and penalties			1
Interest and penalties expense	1
Expiration of statutes of limitations on tax assessments [Member]
Significant Change in Unrecognized Tax Benefits is Reasonably Possible [Line Items]
Possible change in unrecognized tax benefits in next 12 months	(1)	0	0
Potential resolution of audit issues with various U.S. federal, state, and local non-U.S. taxing authorities [Member]
Significant Change in Unrecognized Tax Benefits is Reasonably Possible [Line Items]
Possible change in unrecognized tax benefits in next 12 months	(40)	(8)	(8)
Potential resolution of audit issues with various U.S. federal, state, and local non-U.S. taxing authorities [Member] | San Diego Gas and Electric Company [Member]
Significant Change in Unrecognized Tax Benefits is Reasonably Possible [Line Items]
Possible change in unrecognized tax benefits in next 12 months	(6)	(6)	(6)
Potential resolution of audit issues with various U.S. federal, state, and local non-U.S. taxing authorities [Member] | Southern California Gas Company [Member]
Significant Change in Unrecognized Tax Benefits is Reasonably Possible [Line Items]
Possible change in unrecognized tax benefits in next 12 months	$ (2)	$ (2)	$ (2)