INCOME TAXES - Income Tax Expense (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Income Tax Disclosure [Abstract]
Current income taxes: Federal taxes	$ (3)	$ 8	$ 24	$ 31
Current income taxes: State taxes	0	1	3	4
Total current income taxes	(3)	9	27	35
Deferred income taxes: Federal taxes	19	13	34	28
Deferred income taxes: State taxes	1	0	2	1
Total deferred income taxes	20	13	36	29
Income taxes	$ 17	$ 22	$ 63	$ 64
Statutory tax rate	21.00%	21.00%	21.00%	21.00%
Effective tax rate	14.50%	18.00%	17.80%	19.00%