FAIR VALUE MEASUREMENTS (Schedule of Activity for Debt and Equity Securities) (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Fair Value Disclosures [Abstract]
Proceeds from sales and maturities of nuclear decommissioning trust investments	$ 401	$ 254	$ 952	$ 787
Gross realized gains on securities	74	8	129	76
Gross realized losses on securities	$ (3)	$ (12)	$ (16)	$ (21)