BANK PREMISES AND EQUIPMENT (Details) - USD ($)	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Property, Plant and Equipment [Line Items]
Total cost	$ 138,115,000	$ 119,902,000
Accumulated depreciation	(62,452,000)	(55,828,000)
Net bank premises and equipment	75,663,000	64,074,000
Depreciation expense	7,000,000	6,600,000	$ 6,100,000
Impairment of Long-Lived Assets to be Disposed of	109,000	670,000	$ 93,000
Land [Member]
Property, Plant and Equipment [Line Items]
Total cost	20,780,000	15,786,000
Bank Premises [Member]
Property, Plant and Equipment [Line Items]
Total cost	$ 39,182,000	33,425,000
Bank Premises [Member] | Minimum [Member]
Property, Plant and Equipment [Line Items]
Estimated useful lives	5 years
Bank Premises [Member] | Maximum [Member]
Property, Plant and Equipment [Line Items]
Estimated useful lives	39 years
Leasehold Improvements [Member]
Property, Plant and Equipment [Line Items]
Total cost	$ 22,817,000	20,797,000
Leasehold Improvements [Member] | Minimum [Member]
Property, Plant and Equipment [Line Items]
Estimated useful lives	1 year
Leasehold Improvements [Member] | Maximum [Member]
Property, Plant and Equipment [Line Items]
Estimated useful lives	27 years
Furniture and Equipment [Member]
Property, Plant and Equipment [Line Items]
Total cost	$ 55,336,000	$ 49,894,000
Furniture and Equipment [Member] | Minimum [Member]
Property, Plant and Equipment [Line Items]
Estimated useful lives	1 year
Furniture and Equipment [Member] | Maximum [Member]
Property, Plant and Equipment [Line Items]
Estimated useful lives	12 years