GENERAL INFORMATION AND OTHER FINANCIAL DATA - AFFILIATES REVENUE AND COST OF SALES (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Related Party Transaction [Line Items]
Revenue from related parties	$ 9	$ 13	$ 31	$ 40
Costs of sales to related parties	9	12	35	40
San Diego Gas and Electric Company [Member]
Related Party Transaction [Line Items]
Revenue from related parties	1	2	4	5
Costs of sales to related parties	17	16	56	56
Southern California Gas Company [Member]
Related Party Transaction [Line Items]
Revenue from related parties	23	16	61	50
Costs of sales to related parties	$ 2	$ 2	$ 2	$ 6