Income Tax Expense (Schedule of Gross Deferred Tax Assets and Liabilities) (Details) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013
Gross deferred tax assets:
Allowance for loan losses	$ 10,116	$ 10,033
Defined benefit pension obligations	6,719	3,544
Deferred compensation	2,761	2,545
Deferred loan origination fees	1,822	1,593
Stock based compensation	1,676	1,686
Other	3,026us-gaap_DeferredTaxAssetsOther	3,591us-gaap_DeferredTaxAssetsOther
Gross deferred tax assets	26,120us-gaap_DeferredTaxAssetsGross	22,992us-gaap_DeferredTaxAssetsGross
Gross deferred tax liabilities:
Net unrealized gains on securities available for sale	(2,373)	(1,791)
Amortization of intangibles	(1,750)	(1,977)
Deferred loan origination costs	(4,694)	(3,697)
Loan servicing rights	(1,078)	(971)
Other	(1,206)us-gaap_DeferredTaxLiabilitiesOther	(1,805)us-gaap_DeferredTaxLiabilitiesOther
Gross deferred tax liabilities	(11,101)us-gaap_DeferredIncomeTaxLiabilities	(10,241)us-gaap_DeferredIncomeTaxLiabilities
Net deferred tax asset	$ 15,019us-gaap_DeferredTaxAssetsLiabilitiesNet	$ 12,751us-gaap_DeferredTaxAssetsLiabilitiesNet

Amount of deferred tax liability attributable to taxable temporary differences.

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