INCOME TAXES - COMPONENTS OF TAX EXPENSE (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Current tax expense (benefit):
Federal	$ (212)	$ 26	$ (5)
State	(11)	13	9
Total current	(223)	39	4
Deferred tax expense:
Federal	(246)	175	125
State	(47)	33	19
Total deferred	(293)	208	144
Income tax (benefit) expense	$ (516)	$ 247	$ 148