Fair Value Measurements, Assets or Liabilities Measured at Fair Value on a Non-recurring Basis (Details) - Nonrecurring [Member] - USD ($) $ in Thousands	Sep. 30, 2017	Dec. 31, 2016	Sep. 30, 2016
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Impaired Loans	$ 4,980	$ 1,893	$ 1,930
Other Real Estate	873	3,745	785
Total Assets Measured at Fair Value On a Non-Recurring Basis	5,853	5,638	2,715
Commercial Real Estate [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Impaired Loans	2,594
Residential 1st Mortgage [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Impaired Loans	491	480	496
Home Equity Lines and Loans [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Impaired Loans	78	83	84
Other Real Estate		785	785
Agricultural [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Impaired Loans	298	497	503
Commercial [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Impaired Loans	1,519	833	847
Real Estate Construction [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Other Real Estate	873	2,960
Quoted Prices in Active Markets for Identical Assets (Level 1) [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Impaired Loans	0	0	0
Other Real Estate	0	0	0
Total Assets Measured at Fair Value On a Non-Recurring Basis	0	0	0
Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | Commercial Real Estate [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Impaired Loans	0
Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | Residential 1st Mortgage [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Impaired Loans	0	0	0
Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | Home Equity Lines and Loans [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Impaired Loans	0	0	0
Other Real Estate		0	0
Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | Agricultural [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Impaired Loans	0	0	0
Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | Commercial [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Impaired Loans	0	0	0
Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | Real Estate Construction [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Other Real Estate	0	0
Other Observable Inputs (Level 2) [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Impaired Loans	0	0	0
Other Real Estate	0	0	0
Total Assets Measured at Fair Value On a Non-Recurring Basis	0	0	0
Other Observable Inputs (Level 2) [Member] | Commercial Real Estate [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Impaired Loans	0
Other Observable Inputs (Level 2) [Member] | Residential 1st Mortgage [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Impaired Loans	0	0	0
Other Observable Inputs (Level 2) [Member] | Home Equity Lines and Loans [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Impaired Loans	0	0	0
Other Real Estate		0	0
Other Observable Inputs (Level 2) [Member] | Agricultural [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Impaired Loans	0	0	0
Other Observable Inputs (Level 2) [Member] | Commercial [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Impaired Loans	0	0	0
Other Observable Inputs (Level 2) [Member] | Real Estate Construction [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Other Real Estate	0	0
Significant Unobservable Inputs (Level 3) [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Impaired Loans	4,980	1,893	1,930
Other Real Estate	873	3,745	785
Total Assets Measured at Fair Value On a Non-Recurring Basis	5,853	5,638	2,715
Significant Unobservable Inputs (Level 3) [Member] | Commercial Real Estate [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Impaired Loans	2,594
Significant Unobservable Inputs (Level 3) [Member] | Residential 1st Mortgage [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Impaired Loans	491	480	496
Significant Unobservable Inputs (Level 3) [Member] | Home Equity Lines and Loans [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Impaired Loans	78	83	84
Other Real Estate		785	785
Significant Unobservable Inputs (Level 3) [Member] | Agricultural [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Impaired Loans	298	497	503
Significant Unobservable Inputs (Level 3) [Member] | Commercial [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Impaired Loans	1,519	833	$ 847
Significant Unobservable Inputs (Level 3) [Member] | Real Estate Construction [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Other Real Estate	$ 873	$ 2,960