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Nature of Operations and Summary of Significant Accounting Policies (Narrative) (Details) $ in Thousands | 12 Months Ended
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Dec. 31, 2020 USD ($) Location shares | Dec. 31, 2019 USD ($) shares | Dec. 31, 2018 USD ($)
Accounting Policies [Abstract] |  |  |
Other Real Estate, Foreclosed Assets, and Repossessed Assets | $ 527 | $ 456 |
Number of location of banking operations | Location | 30 |  |
Period for federal fund sold | 1 day |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |  |
Unpaid principal balance of mortgages serviced for others | $ 301,377 | 259,375 |
Capitalized mortgage loans on real estate carrying amount | 2,308 | 2,264 |
Corporation recorded servicing fee revenue | 625 | 626 | $ 651
Deferred Compensation Arrangement with Individual, Share-based Payments [Line Items] |  |  |
Present value of the post retirement benefits payable | 2,810 | 2,875 |
Periodic policy maintenance costs | $ 87 | $ 125 | $ 0
Director [Member] |  |  |
Deferred Compensation Arrangement with Individual, Share-based Payments [Line Items] |  |  |
Eligible shares, total | shares | 176,215 | 205,004 |
Common stock, shares held in Rabbi Trust | shares | 59,162 | 27,069 |
Minimum [Member] |  |  |
Property, Plant and Equipment [Line Items] |  |  |
Useful lives of the related assets | 3 years |  |
Maximum [Member] |  |  |
Property, Plant and Equipment [Line Items] |  |  |
Useful lives of the related assets | 40 years |  |
Commercial, Agricultural, and Residential Portfolio Segments [Member] |  |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |  |
Number of days past due (or more), accrual of interest discontinued | 90 days |  |
Consumer [Member] |  |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |  |
Maximum days of consumer loan charged off | 180 days |  |

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