PREMISES AND EQUIPMENT - Schedule of Premises and Equipment (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Gross	$ 150,570	$ 137,080
Accumulated Depreciation, Depletion and Amortization, Property, Plant, and Equipment	68,132	60,654
Net	82,438	76,426
Depreciation expense	8,198	7,289	$ 6,410
Land
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Gross	20,979	18,662
Buildings
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Gross	74,842	68,584
Furniture and equipment
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Gross	$ 54,749	$ 49,834