TIME DEPOSITS AND SHORT-TERM DEBT (Details) (USD $)	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
TIME DEPOSITS AND SHORT-TERM DEBT [Abstract]
Minimum denomination of certificates of deposit and other time deposits	$ 100,000
Certificates of deposits and other time deposits over $100,000 outstanding	1,200,000,000	1,400,000,000
Interest expense relating to certificate and other time deposits of $100,000 or more	20,800,000	28,700,000	41,700,000
Maturities of time deposits [Abstract]
2014	577,392,000
2015	247,202,000
2016	120,322,000
2017	135,827,000
2018	71,000
Thereafter	142,000
Total	1,080,956,000
Short-term Debt [Line Items]
End of Period Balance	414,611,000	375,433,000	443,320,000
Daily Average Balance	382,104,000	437,511,000	539,136,000
Maximum Outstanding at any Month End	425,053,000	495,880,000	667,397,000
Lines of credit with other banks	659,000,000
Federal Funds Purchased [Member]
Short-term Debt [Line Items]
End of Period Balance	0		0
End of Period Interest Rate (in hundredths)	0.00%		0.00%
Daily Average Balance	1,180,000		877,000
Daily Average Interest Rate (in hundredths)	0.32%		0.11%
Maximum Outstanding at any Month End	0		0
Securities Sold Under Agreement to Repurchase [Member]
Short-term Debt [Line Items]
End of Period Balance	414,611,000	373,933,000	440,593,000
End of Period Interest Rate (in hundredths)	0.07%	0.07%	0.15%
Daily Average Balance	379,871,000	435,931,000	486,621,000
Daily Average Interest Rate (in hundredths)	0.07%	0.10%	0.17%
Maximum Outstanding at any Month End	423,553,000	493,157,000	514,659,000
Period from date of sale that securities generally mature	30 days
Federal Reserve Discount Window Borrowings [Member]
Short-term Debt [Line Items]
Period from date of purchase that borrowings generally mature	90 days
Short-Term FHLB Advances [Member]
Short-term Debt [Line Items]
End of Period Balance	0	1,500,000	2,727,000
End of Period Interest Rate (in hundredths)	0.00%	4.71%	5.72%
Daily Average Balance	1,053,000	1,580,000	51,638,000
Daily Average Interest Rate (in hundredths)	4.71%	5.72%	1.03%
Maximum Outstanding at any Month End	$ 1,500,000	$ 2,723,000	$ 152,738,000
Period from date of purchase that borrowings generally mature	30 days