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	Sep. 30, 2015	Dec. 31, 2014
Financial assets: [Abstract]
Securities available-for-sale	$ 576,713	$ 640,186
Securities held-to-maturity	1,651	1,644
Mortgage servicing rights	3,030	2,968
Quoted Prices in Active Markets for Identical Assets (Level 1) [Member]
Financial assets: [Abstract]
Cash and cash equivalents	163,192	105,517
Certificates of deposits in other banks	0	0
Securities available-for-sale	45,025	25,381
Securities held-to-maturity	0	0
Loans held for sale	2,029	2,321
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	737,657	677,626
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	5,769	8,213
Securities available-for-sale	531,688	614,805
Securities held-to-maturity	1,651	1,644
Loans held for sale	0	0
Loans, net	0	0
Federal Home Loan Bank stock	17,927	17,927
Federal Reserve Bank stock	4,887	4,869
Accrued interest receivable	13,581	13,548
Mortgage servicing rights	0	0
Financial liabilities: [Abstract]
Deposits	2,219,060	2,192,848
Repurchase agreements	0	0
Federal funds purchased	9,215	11,041
Advances from Federal Home Loan Bank	1,233	61,106
Long-term debt	0	0
Accrued interest payable	1,641	908
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	2,793,430	2,691,906
Federal Home Loan Bank stock	0	0
Federal Reserve Bank stock	0	0
Accrued interest receivable	0	0
Mortgage servicing rights	3,030	2,968
Financial liabilities: [Abstract]
Deposits	0	0
Repurchase agreements	256,120	235,193
Federal funds purchased	0	0
Advances from Federal Home Loan Bank	0	0
Long-term debt	49,073	35,615
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	163,192	105,517
Certificates of deposits in other banks	5,759	8,197
Securities available-for-sale	576,713	640,186
Securities held-to-maturity	1,661	1,662
Loans held for sale	1,983	2,264
Loans, net	2,784,920	2,699,377
Federal Home Loan Bank stock	17,927	17,927
Federal Reserve Bank stock	4,887	4,869
Accrued interest receivable	13,581	13,548
Mortgage servicing rights	3,030	2,968
Financial liabilities: [Abstract]
Deposits	2,975,229	2,874,257
Repurchase agreements	256,153	235,186
Federal funds purchased	9,215	11,041
Advances from Federal Home Loan Bank	1,084	61,170
Long-term debt	61,341	61,341
Accrued interest payable	1,641	908
Unrecognized financial instruments [Abstract]
Letters of credit	0	0
Commitments to extend credit	0	0
Forward sale commitments	$ 0	$ 0