Fair Value (Summary of Financial Assets and Liabilities Measured at Fair Value on Recurring Basis) (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Financial Assets:
Available-for-sale Securities	$ 808,477	$ 781,050
Trading account assets	2,488	2,300
Financial Liabilities:
Goodwill impairment	2,830	0	50
Obligations of states and political subdivisions [Member]
Financial Assets:
Available-for-sale Securities	31,207	33,040
Mortgage-backed securities issued or guaranteed by U.S. government sponsored enterprises [Member]
Financial Assets:
Available-for-sale Securities	395,903	358,148
Collateralized mortgage obligations issued or guaranteed by U.S. government sponsored enterprises [Member]
Financial Assets:
Available-for-sale Securities	374,435	381,688
Private issue collateralized mortgage obligations [Member]
Financial Assets:
Available-for-sale Securities	6,932	8,174
Readily Available Market Prices (Level 1) [Member]
Financial Assets:
Trading account assets	2,488	2,300
Readily Available Market Prices (Level 1) [Member] | Fair Value, Measurements, Recurring [Member]
Financial Assets:
Trading account assets	2,488	2,300
Customer interest rate swap agreement
Financial Liabilities:
Interest rate swap agreements
Customer interest rate swap agreement	0	0
Readily Available Market Prices (Level 1) [Member] | Fair Value, Measurements, Recurring [Member] | Obligations of states and political subdivisions [Member]
Financial Assets:
Available-for-sale Securities
Readily Available Market Prices (Level 1) [Member] | Fair Value, Measurements, Recurring [Member] | Mortgage-backed securities issued or guaranteed by U.S. government sponsored enterprises [Member]
Financial Assets:
Available-for-sale Securities
Readily Available Market Prices (Level 1) [Member] | Fair Value, Measurements, Recurring [Member] | Collateralized mortgage obligations issued or guaranteed by U.S. government sponsored enterprises [Member]
Financial Assets:
Available-for-sale Securities
Readily Available Market Prices (Level 1) [Member] | Fair Value, Measurements, Recurring [Member] | Private issue collateralized mortgage obligations [Member]
Financial Assets:
Available-for-sale Securities
Observable Market Data (Level 2) [Member]
Financial Assets:
Available-for-sale Securities	808,477	781,050
Customer interest rate swap agreement	114	496
Financial Liabilities:
Interest rate swap agreements	3,911	11,580
Customer interest rate swap agreement	114	496
Observable Market Data (Level 2) [Member] | Fair Value, Measurements, Recurring [Member]
Financial Assets:
Trading account assets
Customer interest rate swap agreement	114	496
Financial Liabilities:
Interest rate swap agreements	3,911	11,580
Customer interest rate swap agreement	114	496
Observable Market Data (Level 2) [Member] | Fair Value, Measurements, Recurring [Member] | Obligations of states and political subdivisions [Member]
Financial Assets:
Available-for-sale Securities	31,207	33,040
Observable Market Data (Level 2) [Member] | Fair Value, Measurements, Recurring [Member] | Mortgage-backed securities issued or guaranteed by U.S. government sponsored enterprises [Member]
Financial Assets:
Available-for-sale Securities	395,903	358,148
Observable Market Data (Level 2) [Member] | Fair Value, Measurements, Recurring [Member] | Collateralized mortgage obligations issued or guaranteed by U.S. government sponsored enterprises [Member]
Financial Assets:
Available-for-sale Securities	374,435	381,688
Observable Market Data (Level 2) [Member] | Fair Value, Measurements, Recurring [Member] | Private issue collateralized mortgage obligations [Member]
Financial Assets:
Available-for-sale Securities	6,932	8,174
Company Determined Fair Value (Level 3) [Member] | Fair Value, Measurements, Recurring [Member]
Financial Assets:
Trading account assets
Customer interest rate swap agreement
Financial Liabilities:
Interest rate swap agreements
Customer interest rate swap agreement	0	0
Company Determined Fair Value (Level 3) [Member] | Fair Value, Measurements, Recurring [Member] | Obligations of states and political subdivisions [Member]
Financial Assets:
Available-for-sale Securities
Company Determined Fair Value (Level 3) [Member] | Fair Value, Measurements, Recurring [Member] | Mortgage-backed securities issued or guaranteed by U.S. government sponsored enterprises [Member]
Financial Assets:
Available-for-sale Securities
Company Determined Fair Value (Level 3) [Member] | Fair Value, Measurements, Recurring [Member] | Collateralized mortgage obligations issued or guaranteed by U.S. government sponsored enterprises [Member]
Financial Assets:
Available-for-sale Securities
Company Determined Fair Value (Level 3) [Member] | Fair Value, Measurements, Recurring [Member] | Private issue collateralized mortgage obligations [Member]
Financial Assets:
Available-for-sale Securities
Portion at Fair Value Measurement [Member]
Financial Assets:
Available-for-sale Securities	808,477	781,050
Trading account assets	2,488	2,300
Customer interest rate swap agreement	114	496
Financial Liabilities:
Interest rate swap agreements	3,911	11,580
Customer interest rate swap agreement	114	496
Portion at Fair Value Measurement [Member] | Fair Value, Measurements, Recurring [Member]
Financial Assets:
Trading account assets	2,488	2,300
Customer interest rate swap agreement	114	496
Financial Liabilities:
Interest rate swap agreements	3,911	11,580
Customer interest rate swap agreement	114	496
Portion at Fair Value Measurement [Member] | Fair Value, Measurements, Recurring [Member] | Obligations of states and political subdivisions [Member]
Financial Assets:
Available-for-sale Securities	31,207	33,040
Portion at Fair Value Measurement [Member] | Fair Value, Measurements, Recurring [Member] | Mortgage-backed securities issued or guaranteed by U.S. government sponsored enterprises [Member]
Financial Assets:
Available-for-sale Securities	395,903	358,148
Portion at Fair Value Measurement [Member] | Fair Value, Measurements, Recurring [Member] | Collateralized mortgage obligations issued or guaranteed by U.S. government sponsored enterprises [Member]
Financial Assets:
Available-for-sale Securities	374,435	381,688
Portion at Fair Value Measurement [Member] | Fair Value, Measurements, Recurring [Member] | Private issue collateralized mortgage obligations [Member]
Financial Assets:
Available-for-sale Securities	$ 6,932	$ 8,174