INCOME TAXES - Income Tax Expense (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Income Tax Disclosure [Abstract]
Current income taxes: Federal taxes	$ 21	$ 7
Current income taxes: State taxes	2	2
Total current income taxes	23	9
Deferred income taxes: Federal taxes	(1)	2
Deferred income taxes: State taxes	0	0
Total deferred income taxes	(1)	2
Income taxes	$ 22	$ 11
Statutory tax rate	21.00%	21.00%
Effective tax rate	18.90%	18.80%