Fair Value of Financial Assets and Liabilities, Estimated Fair Value Of Financial Instruments and Indication of Level Within Fair Value Hierarchy of Valuation Techniques (Details) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2014	Dec. 31, 2013
Financial assets: [Abstract]
Securities available-for-sale	$ 650,127	$ 609,405
Mortgage servicing rights	3,258	3,424
Quoted Prices in Active Markets for Identical Assets (Level 1) [Member]
Financial assets: [Abstract]
Cash and cash equivalents	193,689	106,641
Certificates of deposits in other banks	0	0
Securities available-for-sale	24,427	52,782
Securities held-to-maturity	0	0
Loans held for sale	1,645	845
Loans, net	0	0
Federal Home Loan Bank stock	0	0
Federal Reserve Bank stock	0	0
Accrued interest receivable	0	0
Mortgage servicing rights	0	0
Financial liabilities: [Abstract]
Deposits	652,170	621,321
Repurchase agreements	0	0
Federal funds purchased	0	0
Advances from Federal Home Loan Bank	0	0
Long-term debt	0	0
Accrued interest payable	0	0
Unrecognized financial instruments: [Abstract]
Letters of credit	0	0
Commitments to extend credit	0	0
Forward sale commitments	0	0
Significant Other Observable Inputs (Level 2) [Member]
Financial assets: [Abstract]
Cash and cash equivalents	0	0
Certificates of deposits in other banks	9,605	9,582
Securities available-for-sale	625,700	556,623
Securities held-to-maturity	1,619	1,601
Loans held for sale	0	0
Loans, net	0	0
Federal Home Loan Bank stock	17,927	25,673
Federal Reserve Bank stock	4,887	4,886
Accrued interest receivable	12,924	12,886
Mortgage servicing rights	0	0
Financial liabilities: [Abstract]
Deposits	2,267,890	2,230,608
Repurchase agreements	0	0
Federal funds purchased	8,723	12,465
Advances from Federal Home Loan Bank	1,500	1,531
Long-term debt	0	0
Accrued interest payable	1,181	1,032
Unrecognized financial instruments: [Abstract]
Letters of credit	0	0
Commitments to extend credit	0	0
Forward sale commitments	0	0
Significant Unobservable Inputs (Level 3) [Member]
Financial assets: [Abstract]
Cash and cash equivalents	0	0
Certificates of deposits in other banks	0	0
Securities available-for-sale	0	0
Securities held-to-maturity	0	0
Loans held for sale	0	0
Loans, net	2,563,294	2,589,811
Federal Home Loan Bank stock	0	0
Federal Reserve Bank stock	0	0
Accrued interest receivable	0	0
Mortgage servicing rights	3,258	3,424
Financial liabilities: [Abstract]
Deposits	0	0
Repurchase agreements	217,630	207,992
Federal funds purchased	0	0
Advances from Federal Home Loan Bank	0	0
Long-term debt	35,244	31,362
Accrued interest payable	0	0
Unrecognized financial instruments: [Abstract]
Letters of credit	0	0
Commitments to extend credit	0	0
Forward sale commitments	0	0
Carrying Amount [Member]
Financial assets: [Abstract]
Cash and cash equivalents	193,689	106,641
Certificates of deposits in other banks	9,568	9,568
Securities available-for-sale	650,127	609,405
Securities held-to-maturity	1,662	1,662
Loans held for sale	1,610	828
Loans, net	2,551,893	2,581,346
Federal Home Loan Bank stock	17,927	25,673
Federal Reserve Bank stock	4,887	4,886
Accrued interest receivable	12,924	12,886
Mortgage servicing rights	3,258	3,424
Financial liabilities: [Abstract]
Deposits	2,924,189	2,855,074
Repurchase agreements	217,656	208,067
Federal funds purchased	8,723	12,465
Advances from Federal Home Loan Bank	1,257	1,286
Long-term debt	61,341	61,341
Accrued interest payable	1,181	1,032
Unrecognized financial instruments: [Abstract]
Letters of credit	0	0
Commitments to extend credit	0	0
Forward sale commitments	$ 0	$ 0