FAIR VALUE MEASUREMENTS (Schedule of Activity for Debt and Equity Securities) (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Fair Value Disclosures [Abstract]
Proceeds from sales and maturities of nuclear decommissioning trust investments	$ 890	$ 346	$ 1,144	$ 808
Gross realized gains on securities	51	45	59	67
Gross realized losses on securities	$ (22)	$ (5)	$ (34)	$ (12)