SIGNIFICANT ACCOUNTING POLICIES AND OTHER FINANCIAL DATA - AFFILIATES REVENUE AND COST OF SALES (Details) $ in Millions	12 Months Ended
Dec. 31, 2019 USD ($) MW	Dec. 31, 2018 USD ($)	Dec. 31, 2017 USD ($)
Related Party Transaction [Line Items]
Related party revenue	$ 52	$ 64	$ 43
Related party cost of sales	50	46	47
San Diego Gas and Electric Company [Member]
Related Party Transaction [Line Items]
Related party revenue	6	5	8
Related party cost of sales	74	73	71
Southern California Gas Company [Member]
Related Party Transaction [Line Items]
Related party revenue	69	64	74
Related party cost of sales	$ 8	$ 0	$ 0
Minimum [Member] \| Federal Funds Rate [Member] \| California Utilities [Member]
Related Party Transaction [Line Items]
Variable percentage rate	0.13%
Maximum [Member] \| Federal Funds Rate [Member] \| California Utilities [Member]
Related Party Transaction [Line Items]
Variable percentage rate	0.20%
Energia Sierra Juarez Wind Project [Member] \| San Diego Gas and Electric Company [Member]
Related Party Transaction [Line Items]
Power purchase agreement term	20 years
Generating capacity (in mw) \| MW	155

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