Income Taxes Components of Deferred Tax Assets and Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Deferred Tax Assets, Gross [Abstract]
Allowance for Loan Losses	$ 4,730	$ 6,609
Pension and Deferred Compensation Plans	2,595	3,961
Pension Liability Included in Accumulated Other Comprehensive Income	2,475	4,023
Other	357	502
Deferred Tax Assets, Unrealized Losses on Trading Securities	426	239
Total Gross Deferred Tax Assets	10,583	15,334
Valuation Allowance for Deferred Tax Assets	0	0
Total Gross Deferred Tax Assets, Net of Valuation Allowance	10,583	15,334
Deferred Tax Liabilities, Gross [Abstract]
Pension Plans	5,487	8,399
Depreciation	955	1,430
Deferred Income	2,779	4,199
Goodwill	3,566	5,324
Total Gross Deferred Tax Liabilites	$ 12,787	$ 19,352