INCOME TAXES - Reconciliation to statutory Federal income tax rate (Details) - USD ($) $ in Thousands		12 Months Ended
	Dec. 22, 2017	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Reconciliation to statutory Federal income tax rate (Amount)
Federal statutory tax rate		$ 12,782	$ 11,775	$ 17,517
Differences resulting from:
State income taxes, net of federal benefit		3,420	1,660	1,139
Permanent book to tax differences		(135)
Deferred tax writedown for enacted tax rate changes				(176)
Other items, net		83	1,232	(327)
Total provision for income taxes		$ 16,150	$ 14,667	$ 18,153
Reconciliation to statutory Federal income tax rate (Percentage)
Federal statutory tax rate	35.00%	21.00%	21.00%	35.00%
Differences resulting from:
State income taxes, net of federal benefit		5.60%	3.00%	2.30%
Permanent book to tax differences		(0.20%)
Deferred tax writedown for enacted tax rate changes				0.30%
Other items, net		0.10%	2.20%	(0.70%)
Total provision for income taxes		26.50%	26.20%	36.30%