FAIR VALUE MEASUREMENTS (Schedule of Activity for Debt and Equity Securities) (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Fair Value Disclosures [Abstract]
Proceeds from sales and maturities of nuclear decommissioning trust investments	$ 171	$ 308	$ 517	$ 802
Gross realized gains on securities	56	11	22	48
Gross realized losses on securities	$ (26)	$ (5)	$ (7)	$ (9)