Fair Value Measurements, Quantitative Information (Details) $ in Thousands	Sep. 30, 2019 USD ($)	Dec. 31, 2018 USD ($)	Sep. 30, 2018 USD ($)
Level 3 [Member] | Commercial Real Estate [Member] | Income Approach [Member] | Capitalization Rate [Member]
Quantitative Information [Abstract]
Impaired loans, measurement input	0.0325	0.0325	0.0325
Level 3 [Member] | Commercial Real Estate [Member] | Income Approach [Member] | Capitalization Rate [Member] | Weighted Average [Member]
Quantitative Information [Abstract]
Impaired loans, measurement input	0.0325	0.0325	0.0325
Level 3 [Member] | Residential 1st Mortgage [Member] | Sales Comparison Approach [Member] | Adjustment for Difference Between Comparable Sales [Member] | Minimum [Member]
Quantitative Information [Abstract]
Impaired loans, measurement input	0.0100	0.01	0.01
Level 3 [Member] | Residential 1st Mortgage [Member] | Sales Comparison Approach [Member] | Adjustment for Difference Between Comparable Sales [Member] | Maximum [Member]
Quantitative Information [Abstract]
Impaired loans, measurement input	0.0450	0.04	0.04
Level 3 [Member] | Residential 1st Mortgage [Member] | Sales Comparison Approach [Member] | Adjustment for Difference Between Comparable Sales [Member] | Weighted Average [Member]
Quantitative Information [Abstract]
Impaired loans, measurement input	0.0281	0.03	0.03
Level 3 [Member] | Home Equity Lines and Loans [Member] | Sales Comparison Approach [Member] | Adjustment for Difference Between Comparable Sales [Member] | Minimum [Member]
Quantitative Information [Abstract]
Impaired loans, measurement input	0.0100	0.01	0.01
Level 3 [Member] | Home Equity Lines and Loans [Member] | Sales Comparison Approach [Member] | Adjustment for Difference Between Comparable Sales [Member] | Maximum [Member]
Quantitative Information [Abstract]
Impaired loans, measurement input	0.0200	0.02	0.02
Level 3 [Member] | Home Equity Lines and Loans [Member] | Sales Comparison Approach [Member] | Adjustment for Difference Between Comparable Sales [Member] | Weighted Average [Member]
Quantitative Information [Abstract]
Impaired loans, measurement input	0.0138	0.02	0.01
Level 3 [Member] | Agricultural [Member] | Income Approach [Member] | Capitalization Rate [Member]
Quantitative Information [Abstract]
Impaired loans, measurement input	0.0325
Level 3 [Member] | Agricultural [Member] | Income Approach [Member] | Capitalization Rate [Member] | Weighted Average [Member]
Quantitative Information [Abstract]
Impaired loans, measurement input	0.0325
Level 3 [Member] | Commercial [Member] | Income Approach [Member] | Capitalization Rate [Member]
Quantitative Information [Abstract]
Impaired loans, measurement input	0.0325
Level 3 [Member] | Commercial [Member] | Income Approach [Member] | Capitalization Rate [Member] | Minimum [Member]
Quantitative Information [Abstract]
Impaired loans, measurement input		0.0295	0.0295
Level 3 [Member] | Commercial [Member] | Income Approach [Member] | Capitalization Rate [Member] | Maximum [Member]
Quantitative Information [Abstract]
Impaired loans, measurement input		0.0870	0.0870
Level 3 [Member] | Commercial [Member] | Income Approach [Member] | Capitalization Rate [Member] | Weighted Average [Member]
Quantitative Information [Abstract]
Impaired loans, measurement input	0.0325	0.0340	0.0340
Level 3 [Member] | Real Estate Construction [Member] | Sales Comparison Approach [Member] | Adjustment for Difference Between Comparable Sales [Member]
Quantitative Information [Abstract]
Other real estate, measurement input	0.1	0.1	0.1
Level 3 [Member] | Real Estate Construction [Member] | Sales Comparison Approach [Member] | Adjustment for Difference Between Comparable Sales [Member] | Weighted Average [Member]
Quantitative Information [Abstract]
Other real estate, measurement input	0.1	0.1	0.1
Nonrecurring [Member]
Quantitative Information [Abstract]
Impaired loans	$ 5,658	$ 5,732	$ 5,621
Other real estate	873	873	873
Nonrecurring [Member] | Commercial Real Estate [Member]
Quantitative Information [Abstract]
Impaired loans	2,587	2,658	2,596
Nonrecurring [Member] | Residential 1st Mortgage [Member]
Quantitative Information [Abstract]
Impaired loans	1,518	1,550	1,476
Nonrecurring [Member] | Home Equity Lines and Loans [Member]
Quantitative Information [Abstract]
Impaired loans	66	70	71
Nonrecurring [Member] | Agricultural [Member]
Quantitative Information [Abstract]
Impaired loans	97
Nonrecurring [Member] | Commercial [Member]
Quantitative Information [Abstract]
Impaired loans	1,390	1,454	1,478
Nonrecurring [Member] | Real Estate Construction [Member]
Quantitative Information [Abstract]
Other real estate	873	873	873
Nonrecurring [Member] | Level 3 [Member]
Quantitative Information [Abstract]
Impaired loans	5,658	5,732	5,621
Other real estate	873	873	873
Nonrecurring [Member] | Level 3 [Member] | Commercial Real Estate [Member]
Quantitative Information [Abstract]
Impaired loans	2,587	2,658	2,596
Nonrecurring [Member] | Level 3 [Member] | Residential 1st Mortgage [Member]
Quantitative Information [Abstract]
Impaired loans	1,518	1,550	1,476
Nonrecurring [Member] | Level 3 [Member] | Home Equity Lines and Loans [Member]
Quantitative Information [Abstract]
Impaired loans	66	70	71
Nonrecurring [Member] | Level 3 [Member] | Agricultural [Member]
Quantitative Information [Abstract]
Impaired loans	97
Nonrecurring [Member] | Level 3 [Member] | Commercial [Member]
Quantitative Information [Abstract]
Impaired loans	1,390	1,454	1,478
Nonrecurring [Member] | Level 3 [Member] | Real Estate Construction [Member]
Quantitative Information [Abstract]
Other real estate	$ 873	$ 873	$ 873