Income Tax (Reconciliation of Income Tax Expense at Federal Statutory Rate to Actual Tax Expense) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Reconciliation of federal statutory to actual tax expense
Federal statutory income tax at 34%	$ 6,496	$ 5,993	$ 5,721
State taxes	145	145	145
Non tax captive insurance income	(310)	(319)
Low income housing credits	(96)	(96)	(96)
Tax-exempt income	(1,453)	(1,404)	(1,111)
Effect of "Tax Cuts and Jobs Act"	2,000
Other	11	67	(81)
Income Tax Expense (Benefit), Total	$ 6,793	$ 4,386	$ 4,578
Effective tax rate	35.55%	24.88%	27.21%
Federal statutory income tax rate	34.00%