INCOME TAXES, Effective Tax Rate Reconciliation (Details)	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Effective tax rate reconciliation [Abstract]
Federal statutory income tax rate	21.00%	35.00%	35.00%
Increase (reduction) in taxes resulting from [Abstract]
Tax-exempt interest	(1.60%)	(3.80%)	(4.00%)
State income taxes, net of federal benefit	3.40%	2.50%	2.70%
Stock-based compensation	(0.90%)	(2.00%)	(0.00%)
Federal deferred tax revaluation adjustment	0.00%	(23.70%)	0.00%
Federal tax credits	(1.40%)	(1.50%)	(0.00%)
Other, net	0.30%	(0.70%)	(0.90%)
Effective income tax rate	20.80%	5.80%	32.80%