Fair Value (Assets and Liabilities Measured at Fair Value on Recurring Basis) (Details) - Fair Value, Measurements, Recurring - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Securities	$ 739,980	$ 740,994
Loans Held-for-Sale	9,178	6,719
Derivative Assets	3,490	1,564
Mortgage Servicing Rights	1,023	547
Derivative Liabilities	3,425	1,633
Obligations of State and Political Subdivisions
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Securities	284,039	273,309
MBS/CMO - Residential
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Securities	455,588	467,332
Equity Securities
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Securities	353	353
Quoted Prices in Active Markets for Identical Assets (Level 1)
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Securities	0	0
Loans Held-for-Sale	0	0
Derivative Assets	0	0
Mortgage Servicing Rights	0	0
Derivative Liabilities	0	0
Quoted Prices in Active Markets for Identical Assets (Level 1) | Obligations of State and Political Subdivisions
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Securities	0	0
Quoted Prices in Active Markets for Identical Assets (Level 1) | MBS/CMO - Residential
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Securities	0	0
Quoted Prices in Active Markets for Identical Assets (Level 1) | Equity Securities
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Securities	0	0
Significant Other Observable Inputs (Level 2)
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Securities	734,964	734,992
Loans Held-for-Sale	9,178	6,719
Derivative Assets	3,490	1,564
Mortgage Servicing Rights	1,023	547
Derivative Liabilities	3,425	1,633
Significant Other Observable Inputs (Level 2) | Obligations of State and Political Subdivisions
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Securities	279,376	267,660
Significant Other Observable Inputs (Level 2) | MBS/CMO - Residential
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Securities	455,588	467,332
Significant Other Observable Inputs (Level 2) | Equity Securities
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Securities	0	0
Significant Unobservable Inputs (Level 3)
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Securities	5,016	6,002
Loans Held-for-Sale	0	0
Derivative Assets	0	0
Mortgage Servicing Rights	0	0
Derivative Liabilities	0	0
Significant Unobservable Inputs (Level 3) | Obligations of State and Political Subdivisions
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Securities	4,663	5,649
Significant Unobservable Inputs (Level 3) | MBS/CMO - Residential
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Securities	0	0
Significant Unobservable Inputs (Level 3) | Equity Securities
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Securities	$ 353	$ 353