TIME DEPOSITS AND SHORT-TERM DEBT (Details) (USD $)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Short-term Debt [Line Items]
Certificates of deposits and other time deposits over $100,000 outstanding	$ 948,100,000	$ 1,100,000,000
Interest expense relating to certificate and other time deposits of $100,000 or more	11,400,000	16,000,000	20,800,000
Maturities of time deposits [Abstract]
2016	314,836,000
2017	185,858,000
2018	113,533,000
2019	170,331,000
2020	17,275,000
Thereafter	36,000
Total	801,869,000
End of Period Balance	391,666,000	421,028,000	414,611,000
Daily Average Balance	444,230,000	418,119,000	382,104,000
Maximum Outstanding at any Month End	582,663,000	473,753,000	425,053,000
Lines of credit with other banks	696,000,000
Federal Funds Purchased [Member]
Maturities of time deposits [Abstract]
Daily Average Balance	4,247,000	1,238,000
Daily Average Interest Rate (in hundredths)	0.18%	0.33%
Maximum Outstanding at any Month End	10,000,000
Period from date of sale that securities generally mature	30 days
Securities Sold Under Agreements to Repurchase [Member]
Maturities of time deposits [Abstract]
End of Period Balance	388,166,000	421,028,000	414,611,000
End of Period Interest Rate (in hundredths)	0.08%	0.07%	0.07%
Daily Average Balance	436,875,000	416,881,000	379,871,000
Daily Average Interest Rate (in hundredths)	0.07%	0.07%	0.07%
Maximum Outstanding at any Month End	569,163,000	473,753,000	423,553,000
Federal Reserve Bank Advances [Member]
Maturities of time deposits [Abstract]
Period from date of purchase that borrowings generally mature	90 days
Federal Home Loan Bank [Member]
Maturities of time deposits [Abstract]
End of Period Balance	3,500,000
Daily Average Balance	3,108,000		1,053,000
Daily Average Interest Rate (in hundredths)	2.60%		4.71%
Maximum Outstanding at any Month End	$ 3,500,000		$ 1,500,000
Period from date of purchase that borrowings generally mature	30 days