INCOME TAXES - Income Tax Expense (Details) - USD ($) $ in Millions	3 Months Ended	9 Months Ended
Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Income Tax Disclosure [Abstract]
Current income taxes: Federal taxes	$ 16	$ (3)	$ 62	$ 24
Current income taxes: State taxes	1	0	6	3
Total current income taxes	17	(3)	68	27
Deferred income taxes: Federal taxes	0	19	(24)	34
Deferred income taxes: State taxes	0	1	0	2
Total deferred income taxes	0	20	(24)	36
Income taxes	$ 17	$ 17	$ 44	$ 63
Statutory tax rate	21.00%	21.00%	21.00%	21.00%
Effective tax rate	17.00%	14.50%	17.00%	17.80%

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