TAXES - Details of General Taxes (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
General Taxes
KWH excise	$ 183	$ 191	$ 198
State gross receipts	182	185	192
Real and personal property	541	504	478
Social security and unemployment	112	100	103
Other	28	28	22
Total general taxes	$ 1,046	$ 1,008	$ 993