FAIR VALUE DISCLOSURES (Assets and Liabilities Measured at Fair Value on a Recurring Basis) (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2013 Minimum [Member]	Dec. 31, 2013 Maximum [Member]	Dec. 31, 2013 Fair Value, Measurements, Recurring [Member]	Dec. 31, 2012 Fair Value, Measurements, Recurring [Member]	Dec. 31, 2013 Fair Value, Measurements, Recurring [Member] Level 1 [Member]	Dec. 31, 2012 Fair Value, Measurements, Recurring [Member] Level 1 [Member]	Dec. 31, 2013 Fair Value, Measurements, Recurring [Member] Level 2 [Member]	Dec. 31, 2012 Fair Value, Measurements, Recurring [Member] Level 2 [Member]	Dec. 31, 2013 Fair Value, Measurements, Recurring [Member] Level 3 [Member]	Dec. 31, 2012 Fair Value, Measurements, Recurring [Member] Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative interest rate		1.50%	3.50%
Percentage rate deduction to determine the fair value of other real estate owned (in hundredths)	7.00%
Available-for-sale securities [Abstract]
U.S. Government agencies				$ 1,458,349	$ 1,401,996			$ 1,458,349	$ 1,401,996
Government agency issued residential mortgage-backed securities				250,234	366,875			250,234	366,875
Government agency issued commercial mortgage-backed securities				230,912	91,445			230,912	91,445
Obligations of states and political subdivisions				519,405	565,873			519,405	565,873
Other				8,089	7,843	1,102	744	6,987	7,099
Mortgage servicing rights				54,662	37,882					54,662	37,882
Derivative instruments				30,230	55,684					30,230	55,684
Total				2,551,881	2,527,598	1,102	744	2,465,887	2,433,288	84,892	93,566
Liabilities [Abstract]
Derivative instruments				$ 29,352	$ 52,773					$ 29,352	$ 52,773