Income Taxes (Schedule of Deferred Tax Assets and Deferred Tax Liabilities) (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Asset
Net operating loss and tax credit carryforward	$ 12,078	$ 20,977
Allowance for loan losses	5,201	8,094
Pension and other benefits	3,363	5,141
Net unrealized losses on AFS securities	2,821	3,227
Net unrealized losses on derivative instruments	1,623	3,066
Deferred compensation and benefits	1,199	1,791
Net unrealized losses on postretirement plans	1,092	1,147
Purchase accounting and deposit premium	461	1,430
Total	27,838	45,829
Liability
Depreciation	(2,857)	(4,520)
Deferred loan origination fees	(1,510)	(2,046)
Other		(956)
Deferred Tax Liabilities, Other	695
Total	(5,062)	(6,566)
Income Tax Contingency [Line Items]
Deferred Tax Assets, Net of Valuation Allowance	$ 22,776	$ 39,263