Income Taxes Effective Income Tax Rate, Continuing Operations, Tax Rate Reconciliation (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Effective Income Tax Rate Reconciliation, Percent [Abstract]
Computed Tax Expense at Statutory Rate	$ 13,212	$ 12,345	$ 11,737
Tax-Exempt Income	(2,437)	(2,292)	(2,215)
Nondeductible Interest Expense	40	36	51
State Taxes, Net of Federal Income Tax Benefit	554	805	791
Other Items, Net	(154)	(284)	(190)
Income Tax Expense (Benefit), Continuing Operations	$ 11,215	$ 10,610	$ 10,174