FAIR VALUE MEASUREMENTS (Schedule of Activity for Debt and Equity Securities) (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Fair Value Disclosures [Abstract]
Proceeds from sales and maturities of nuclear decommissioning trust investments	$ 346	$ 319	$ 808	$ 1,121
Gross realized gains on securities	45	3	67	51
Gross realized losses on securities	$ (5)	$ (5)	$ (12)	$ (14)