BANK PREMISES AND EQUIPMENT (Details) (USD $)	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Property, Plant and Equipment [Line Items]
Total cost	$ 102,118,000	$ 90,562,000
Accumulated depreciation	(46,891,000)	(42,310,000)
Net bank premises and equipment	55,227,000	48,252,000
Depreciation expense	5,500,000	4,900,000	5,200,000
Land [Member]
Property, Plant and Equipment [Line Items]
Total cost	14,514,000	11,523,000
Bank Premises [Member]
Property, Plant and Equipment [Line Items]
Total cost	24,160,000	21,438,000
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	19,681,000	18,744,000
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	15 years
Furniture and Equipment [Member]
Property, Plant and Equipment [Line Items]
Total cost	$ 43,763,000	$ 38,857,000
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	10 years