INCOME TAXES - U.S. Federal Statutory Income Tax Rate Reconciled to Effective Tax Rate (Details) - USD ($) $ in Millions	12 Months Ended
Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Income Tax Disclosure [Abstract]
Pre-Tax Income	$ 357	$ 270	$ 241
Tax Expense/(Benefit)
U.S. federal statutory tax rate	75	57	51
State income taxes, net of federal benefit	25	20	18
Nondeductible meals, entertainment and penalties	0	1	1
Stock based compensation	(2)	(1)	(9)
Uncertain tax positions	1	0	1
Tax credits	(6)	(7)	(5)
State and tax return to provision adjustments	(7)	(8)	(7)
Sec 199 benefits	0	(1)	0
Other	(1)	(3)	(1)
Total	$ 85	$ 58	$ 49
Percent of Pre-Tax Income (Loss)
U.S. federal statutory tax rate	21.00%	21.00%	21.00%
State income taxes, net of federal benefit	7.00%	7.00%	8.00%
Nondeductible meals, entertainment and penalties	0.00%	0.00%	0.00%
Stock based compensation	0.00%	0.00%	(4.00%)
Uncertain tax positions	0.00%	0.00%	0.00%
Tax credits	(2.00%)	(3.00%)	(2.00%)
State and tax return to provision adjustments	(2.00%)	(3.00%)	(3.00%)
Sec 199 benefits	0.00%	0.00%	0.00%
Other	0.00%	(1.00%)	0.00%
Total	24.00%	21.00%	20.00%

Percentage of current income tax expense (benefit) and deferred income tax expense (benefit) pertaining to continuing operations.

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