Fair Value (Reconciliation of all Assets Measured at Fair Value on a Recurring Basis, Using Significant Unobservable Inputs (Level 3)) (Details) - Fair Value, Measurements, Recurring - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Obligations of State and Political Subdivisions
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance of Recurring Level 3 Assets at January 1	$ 7,024	$ 8,749
Total Gains or Losses Included in Other Comprehensive Income	(60)	(75)
Maturities / Calls	(1,315)	(1,650)
Purchases	0	0
Balance of Recurring Level 3 Assets at December 31	5,649	7,024
Equity Securities
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance of Recurring Level 3 Assets at January 1	353	353
Total Gains or Losses Included in Other Comprehensive Income	0	0
Maturities / Calls	0	0
Purchases	0	0
Balance of Recurring Level 3 Assets at December 31	$ 353	$ 353