PREMISES AND EQUIPMENT (Components of Premises and Equipment) (Detail) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Property, Plant and Equipment [Abstract]
Land	$ 10,160	$ 10,160
Buildings and leasehold improvements	64,278	62,215
Equipment	37,452	35,152
Total premises and equipment	111,890	107,527
Less: accumulated depreciation and amortization	(57,129)	(53,965)
Net premises and equipment	$ 54,761	$ 53,562