Income Taxes (Schedule of Deferred Tax Assets and Deferred Tax Liabilities) (Details) (USD $) In Thousands, unless otherwise specified			12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2012 Minimum [Member]	Dec. 31, 2012 Maximum [Member]
Asset
Allowance for possible losses on loans	$ 8,081	$ 8,061
Allowance for OTTI of investments	71	5,352
Allowance for OREO valuation	149	179
Pension and other benefits	3,715	3,690
Depreciation
Deferred loan origination fees
Deferred compensation and benefits	904	890
Net unrealized gains on investments available for sale and derivative instruments
Net unrealized losses on postretirement plans	1,476	970
Purchase accounting	760	571
Deposit premium
Mortgage servicing rights
Prepaid expenses
Other	706	480
Total	15,862	20,193
Liability
Allowance for possible losses on loans
Allowance for OTTI of investments
Allowance for OREO valuation
Pension and other benefits
Depreciation	2,073	1,687
Deferred loan origination fees	1,256	1,155
Deferred compensation and benefits
Net unrealized gains on investments available for sale and derivative instruments	3,090	2,080
Net unrealized losses on postretirement plans
Purchase accounting
Deposit premium	907	937
Mortgage servicing rights	190	269
Prepaid expenses	683	579
Other
Total	$ 8,199	$ 6,707
Income Tax Contingency [Line Items]
Open tax years			2009	2012