Fair Value Measurements, Quantitative Information (Details) $ in Thousands	Mar. 31, 2021 USD ($)	Dec. 31, 2020 USD ($)	Mar. 31, 2020 USD ($)
Level 3 [Member] | Commercial Real Estate [Member] | Income Approach [Member] | Capitalization Rate [Member]
Quantitative Information [Abstract]
Impaired loans, measurement input	0.07
Level 3 [Member] | Commercial Real Estate [Member] | Income Approach [Member] | Capitalization Rate [Member] | Weighted Average [Member]
Quantitative Information [Abstract]
Impaired loans, measurement input	0.07
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	0.0071	0.0072	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	0.0410	0.0413	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	0.0255	0.0257	0.0284
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	0.011	0.011	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	0.013	0.014	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	0.0123	0.0125	0.0107
Level 3 [Member] | Agricultural [Member] | Income Approach [Member] | Capitalization Rate [Member]
Quantitative Information [Abstract]
Impaired loans, measurement input		0.10
Level 3 [Member] | Agricultural [Member] | Income Approach [Member] | Capitalization Rate [Member] | Weighted Average [Member]
Quantitative Information [Abstract]
Impaired loans, measurement input		0.10
Level 3 [Member] | Commercial [Member] | Income Approach [Member] | Capitalization Rate [Member]
Quantitative Information [Abstract]
Impaired loans, measurement input	0.10	0.10
Level 3 [Member] | Commercial [Member] | Income Approach [Member] | Capitalization Rate [Member] | Weighted Average [Member]
Quantitative Information [Abstract]
Impaired loans, measurement input	0.10	0.10
Level 3 [Member] | Consumer [Member] | Income Approach [Member] | Adjustment for Difference Between Comparable Sales [Member]
Quantitative Information [Abstract]
Impaired loans, measurement input	0.10
Level 3 [Member] | Consumer [Member] | Income Approach [Member] | Adjustment for Difference Between Comparable Sales [Member] | Weighted Average [Member]
Quantitative Information [Abstract]
Impaired loans, measurement input	0.10
Level 3 [Member] | Consumer [Member] | Sales Comparison Approach [Member] | Adjustment for Difference Between Comparable Sales [Member]
Quantitative Information [Abstract]
Impaired loans, measurement input		0.10	0.04
Level 3 [Member] | Consumer [Member] | Sales Comparison Approach [Member] | Adjustment for Difference Between Comparable Sales [Member] | Weighted Average [Member]
Quantitative Information [Abstract]
Impaired loans, measurement input		0.10	0.04
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	0.10	0.10	0.10
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	0.10	0.10	0.10
Nonrecurring [Member]
Quantitative Information [Abstract]
Impaired loans	$ 2,064	$ 2,396	$ 1,669
Other real estate	873	873	873
Nonrecurring [Member] | Commercial Real Estate [Member]
Quantitative Information [Abstract]
Impaired loans	82
Nonrecurring [Member] | Residential 1st Mortgage [Member]
Quantitative Information [Abstract]
Impaired loans	1,572	1,584	1,470
Nonrecurring [Member] | Home Equity Lines and Loans [Member]
Quantitative Information [Abstract]
Impaired loans	60	61	64
Nonrecurring [Member] | Agricultural [Member]
Quantitative Information [Abstract]
Impaired loans		400
Nonrecurring [Member] | Commercial [Member]
Quantitative Information [Abstract]
Impaired loans	212	213
Nonrecurring [Member] | Consumer [Member]
Quantitative Information [Abstract]
Impaired loans	138	138	135
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	2,064	2,396	1,669
Other real estate	873	873	873
Nonrecurring [Member] | Level 3 [Member] | Commercial Real Estate [Member]
Quantitative Information [Abstract]
Impaired loans	82
Nonrecurring [Member] | Level 3 [Member] | Residential 1st Mortgage [Member]
Quantitative Information [Abstract]
Impaired loans	1,572	1,584	1,470
Nonrecurring [Member] | Level 3 [Member] | Home Equity Lines and Loans [Member]
Quantitative Information [Abstract]
Impaired loans	60	61	64
Nonrecurring [Member] | Level 3 [Member] | Agricultural [Member]
Quantitative Information [Abstract]
Impaired loans		400
Nonrecurring [Member] | Level 3 [Member] | Commercial [Member]
Quantitative Information [Abstract]
Impaired loans	212	213
Nonrecurring [Member] | Level 3 [Member] | Consumer [Member]
Quantitative Information [Abstract]
Impaired loans	138	138	135
Nonrecurring [Member] | Level 3 [Member] | Real Estate Construction [Member]
Quantitative Information [Abstract]
Other real estate	$ 873	$ 873	$ 873