Fair Value Measurements, Quantitative Information (Details) $ in Thousands	Sep. 30, 2021 USD ($)	Dec. 31, 2020 USD ($)	Sep. 30, 2020 USD ($)
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	0.0068	0.0072	0.0073
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	0.0402	0.0413	0.0416
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	0.0254	0.0257	0.0258
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	0.011
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	0.014
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	0.0120	0.0125	0.0128
Level 3 [Member] | Agricultural [Member] | Income Approach [Member] | Capitalization Rate [Member]
Quantitative Information [Abstract]
Impaired loans, measurement input		0.10	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	0.10
Level 3 [Member] | Commercial [Member] | Income Approach [Member] | Capitalization Rate [Member]
Quantitative Information [Abstract]
Impaired loans, measurement input	0.10	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	0.10
Level 3 [Member] | Consumer [Member] | Income Approach [Member] | Capitalization Rate [Member]
Quantitative Information [Abstract]
Impaired loans, measurement input	0.10
Level 3 [Member] | Consumer [Member] | Income Approach [Member] | Capitalization Rate [Member] | Weighted Average [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]
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] | Weighted Average [Member]
Quantitative Information [Abstract]
Impaired loans, measurement input		0.10	0.10
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	$ 1,822	$ 2,396	$ 2,421
Other real estate	873	873	873
Nonrecurring [Member] | Residential 1st Mortgage [Member]
Quantitative Information [Abstract]
Impaired loans	1,423	1,584	1,599
Nonrecurring [Member] | Home Equity Lines and Loans [Member]
Quantitative Information [Abstract]
Impaired loans	57	61	62
Nonrecurring [Member] | Agricultural [Member]
Quantitative Information [Abstract]
Impaired loans		400	400
Nonrecurring [Member] | Commercial [Member]
Quantitative Information [Abstract]
Impaired loans	204	213	222
Nonrecurring [Member] | Consumer [Member]
Quantitative Information [Abstract]
Impaired loans	138	138	138
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	1,822	2,396	2,421
Other real estate	873	873	873
Nonrecurring [Member] | Level 3 [Member] | Residential 1st Mortgage [Member]
Quantitative Information [Abstract]
Impaired loans	1,423	1,584	1,599
Nonrecurring [Member] | Level 3 [Member] | Home Equity Lines and Loans [Member]
Quantitative Information [Abstract]
Impaired loans	57	61	62
Nonrecurring [Member] | Level 3 [Member] | Agricultural [Member]
Quantitative Information [Abstract]
Impaired loans		400	400
Nonrecurring [Member] | Level 3 [Member] | Commercial [Member]
Quantitative Information [Abstract]
Impaired loans	204	213	222
Nonrecurring [Member] | Level 3 [Member] | Consumer [Member]
Quantitative Information [Abstract]
Impaired loans	138	138	138
Nonrecurring [Member] | Level 3 [Member] | Real Estate Construction [Member]
Quantitative Information [Abstract]
Other real estate	$ 873	$ 873	$ 873