INCOME TAXES - Income Tax Expense (Details) - USD ($) $ in Millions	3 Months Ended	6 Months Ended
Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Income Tax Disclosure [Abstract]
Current income taxes: Federal taxes	$ 39	$ 9	$ 46	$ 27
Current income taxes: State taxes	3	1	5	3
Total current income taxes	42	10	51	30
Deferred income taxes: Federal taxes	(26)	13	(24)	15
Deferred income taxes: State taxes	0	1	0	1
Total deferred income taxes	(26)	14	(24)	16
Income taxes	$ 16	$ 24	$ 27	$ 46
Statutory tax rate	21.00%	21.00%	21.00%	21.00%
Effective tax rate	16.00%	19.70%	17.00%	19.50%

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