GENERAL INFORMATION AND OTHER FINANCIAL DATA - AFFILIATES REVENUE AND COST OF SALES (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Related Party Transaction [Line Items]
Revenue from related parties	$ 7	$ 10	$ 15	$ 22
Costs of sales to related parties	0	15	11	26
Interest income	12	15	27	32
Interest expense	3	4	7	7
San Diego Gas and Electric Company [Member]
Related Party Transaction [Line Items]
Revenue from related parties	2	2	4	3
Costs of sales to related parties	27	22	55	39
Southern California Gas Company [Member]
Related Party Transaction [Line Items]
Revenue from related parties	23	20	48	38
Costs of sales to related parties	$ 0	$ 0	$ 3	$ 0