GENERAL INFORMATION AND OTHER FINANCIAL DATA - AFFILIATES REVENUE AND COST OF SALES (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Related Party Transaction [Line Items]
Revenue from related parties	$ 7	$ 9	$ 22	$ 31
Costs of sales to related parties	0	9	11	35
Interest income	11	12	38	44
Interest expense	4	4	11	11
San Diego Gas and Electric Company [Member]
Related Party Transaction [Line Items]
Revenue from related parties	3	1	7	4
Costs of sales to related parties	20	17	75	56
Southern California Gas Company [Member]
Related Party Transaction [Line Items]
Revenue from related parties	24	23	72	61
Costs of sales to related parties	$ (2)	$ 2	$ 1	$ 2