INCOME TAXES - EFFECTIVE INCOME TAX RECONCILIATION (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Business Acquisition [Line Items]
U.S. federal tax rate	21.00%	35.00%	35.00%
Income before income tax	$ 1,016	$ 585	$ 1,159
Expected tax expense	213	123	406
Nondeductible expenses	9	9	5
State income taxes	36	21	28
State income sourcing	1	0	9
Tax law changes	(9)	(7)	(237)
Other—net	(3)	2	(12)
Income tax expense	$ 247	$ 148	$ 199
Effective tax rate	24.30%	25.30%	17.20%