INCOME TAXES - Schedule of Provision (Benefit) for Income Taxes (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Current (benefit) provision for income taxes:
Federal	$ (126)	$ (89)	$ 59
State	9	(2)	8
Current income tax expense (benefit)	(117)	(91)	67
Deferred benefit for income taxes:
Federal	(584)	(4)	(69)
State	(19)	(1)	(34)
Deferred income tax expense (benefit)	(603)	(5)	(103)
Benefit for income taxes	$ (720)	$ (96)	$ (36)