Income Tax Expense (Schedule of Gross Deferred Tax Assets and Liabilities) (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Deferred tax assets:
Allowance for loan losses	$ 6,225	$ 9,621
Defined benefit pension obligations	1,767	3,804
Deferred compensation	3,334	3,991
Deferred loan origination fees	1,325	1,999
Stock based compensation	1,240	1,519
Net unrealized losses on available for sale securities	2,314	4,008
Other	2,281	3,495
Deferred tax assets	18,486	28,437
Deferred tax liabilities:
Amortization of intangibles	(2,148)	(3,765)
Deferred loan origination costs	(3,550)	(5,156)
Loan servicing rights	(849)	(1,293)
Other	(1,200)	(1,419)
Deferred tax liabilities	(7,747)	(11,633)
Net deferred tax asset	$ 10,739	$ 16,804