FAIR VALUE MEASUREMENT (Summary of Financial Assets and Liabilities Measured at Fair Value on Recurring Basis) (Details) (USD $) In Thousands, unless otherwise specified	Sep. 30, 2014	Dec. 31, 2013
Financial Assets:
Available-for-sale Securities	$ 771,806	$ 808,477
Trading account assets	2,418	2,488
Customer interest rate swap agreements	506	114
Financial Liabilities:
Interest rate swap agreements	6,969	3,911
Customer interest rate swap agreements	506	114
US Government-sponsored Enterprises Debt Securities
Financial Assets:
Available-for-sale Securities	4,982
Obligations of states and political subdivisions
Financial Assets:
Available-for-sale Securities	28,046	31,207
Mortgage-backed securities issued or guaranteed by U.S. government sponsored enterprises
Financial Assets:
Available-for-sale Securities	378,204	395,903
Collateralized mortgage obligations issued or guaranteed by U.S. government sponsored enterprises
Financial Assets:
Available-for-sale Securities	354,313	374,435
Private issue collateralized mortgage obligations
Financial Assets:
Available-for-sale Securities	6,261	6,932
Fair Value, Measurements, Recurring
Financial Assets:
Trading account assets	2,418	2,488
Customer interest rate swap agreements	506	114
Financial Liabilities:
Interest rate swap agreements	6,969	3,911
Customer interest rate swap agreements	506	114
Fair Value, Measurements, Recurring | US Government-sponsored Enterprises Debt Securities
Financial Assets:
Available-for-sale Securities	4,982
Fair Value, Measurements, Recurring | Obligations of states and political subdivisions
Financial Assets:
Available-for-sale Securities	28,046	31,207
Fair Value, Measurements, Recurring | Mortgage-backed securities issued or guaranteed by U.S. government sponsored enterprises
Financial Assets:
Available-for-sale Securities	378,204	395,903
Fair Value, Measurements, Recurring | Collateralized mortgage obligations issued or guaranteed by U.S. government sponsored enterprises
Financial Assets:
Available-for-sale Securities	354,313	374,435
Fair Value, Measurements, Recurring | Private issue collateralized mortgage obligations
Financial Assets:
Available-for-sale Securities	6,261	6,932
Readily Available Market Prices (Level 1)
Financial Assets:
Available-for-sale Securities	0	0
Trading account assets	2,418	2,488
Customer interest rate swap agreements	0	0
Financial Liabilities:
Interest rate swap agreements	0	0
Customer interest rate swap agreements	0	0
Readily Available Market Prices (Level 1) | Fair Value, Measurements, Recurring
Financial Assets:
Trading account assets		2,488
Customer interest rate swap agreements
Financial Liabilities:
Interest rate swap agreements
Customer interest rate swap agreements	0	0
Readily Available Market Prices (Level 1) | Fair Value, Measurements, Recurring | US Government-sponsored Enterprises Debt Securities
Financial Assets:
Available-for-sale Securities
Readily Available Market Prices (Level 1) | Fair Value, Measurements, Recurring | Obligations of states and political subdivisions
Financial Assets:
Available-for-sale Securities
Readily Available Market Prices (Level 1) | Fair Value, Measurements, Recurring | Mortgage-backed securities issued or guaranteed by U.S. government sponsored enterprises
Financial Assets:
Available-for-sale Securities
Readily Available Market Prices (Level 1) | Fair Value, Measurements, Recurring | Collateralized mortgage obligations issued or guaranteed by U.S. government sponsored enterprises
Financial Assets:
Available-for-sale Securities
Readily Available Market Prices (Level 1) | Fair Value, Measurements, Recurring | Private issue collateralized mortgage obligations
Financial Assets:
Available-for-sale Securities
Trading account assets	2,418
Observable Market Data (Level 2)
Financial Assets:
Available-for-sale Securities	771,806	808,477
Trading account assets	0	0
Customer interest rate swap agreements	506	114
Financial Liabilities:
Interest rate swap agreements	6,969	3,911
Customer interest rate swap agreements	506	114
Observable Market Data (Level 2) | Fair Value, Measurements, Recurring
Financial Assets:
Trading account assets
Customer interest rate swap agreements	506	114
Financial Liabilities:
Interest rate swap agreements	6,969	3,911
Customer interest rate swap agreements	506	114
Observable Market Data (Level 2) | Fair Value, Measurements, Recurring | US Government-sponsored Enterprises Debt Securities
Financial Assets:
Available-for-sale Securities	4,982
Observable Market Data (Level 2) | Fair Value, Measurements, Recurring | Obligations of states and political subdivisions
Financial Assets:
Available-for-sale Securities	28,046	31,207
Observable Market Data (Level 2) | Fair Value, Measurements, Recurring | Mortgage-backed securities issued or guaranteed by U.S. government sponsored enterprises
Financial Assets:
Available-for-sale Securities	378,204	395,903
Observable Market Data (Level 2) | Fair Value, Measurements, Recurring | Collateralized mortgage obligations issued or guaranteed by U.S. government sponsored enterprises
Financial Assets:
Available-for-sale Securities	354,313	374,435
Observable Market Data (Level 2) | Fair Value, Measurements, Recurring | Private issue collateralized mortgage obligations
Financial Assets:
Available-for-sale Securities	6,261	6,932
Company Determined Fair Value (Level 3)
Financial Assets:
Available-for-sale Securities	0	0
Trading account assets	0	0
Customer interest rate swap agreements	0	0
Financial Liabilities:
Interest rate swap agreements	0	0
Customer interest rate swap agreements	0	0
Company Determined Fair Value (Level 3) | Fair Value, Measurements, Recurring
Financial Assets:
Trading account assets
Customer interest rate swap agreements
Financial Liabilities:
Interest rate swap agreements
Customer interest rate swap agreements	0	0
Company Determined Fair Value (Level 3) | Fair Value, Measurements, Recurring | US Government-sponsored Enterprises Debt Securities
Financial Assets:
Available-for-sale Securities
Company Determined Fair Value (Level 3) | Fair Value, Measurements, Recurring | Obligations of states and political subdivisions
Financial Assets:
Available-for-sale Securities
Company Determined Fair Value (Level 3) | Fair Value, Measurements, Recurring | Mortgage-backed securities issued or guaranteed by U.S. government sponsored enterprises
Financial Assets:
Available-for-sale Securities
Company Determined Fair Value (Level 3) | Fair Value, Measurements, Recurring | Collateralized mortgage obligations issued or guaranteed by U.S. government sponsored enterprises
Financial Assets:
Available-for-sale Securities
Company Determined Fair Value (Level 3) | Fair Value, Measurements, Recurring | Private issue collateralized mortgage obligations
Financial Assets:
Available-for-sale Securities