Summary of Significant Accounting Policies (Narrative) (Details) - USD ($)	12 Months Ended
Dec. 31, 2019	Dec. 31, 2018
Summary of Significant Accounting Policies [Line Items]
Concentration of credit, benchmark description	Otherwise, there were no concentrations of credit to any particular industry equaling more than 10% of total capital.
Maturity of interest-bearing time deposits	5 years
Held-to-maturity securities	$ 0	$ 0
Net unamortized origination costs	$ 70,000	11,000
Usual period of lines of credit for commercial, financial and agricultural lending	5 years
Other real estate owned		744,000
Goodwill impairment loss	$ 0	0
Mortgage servicing rights	180,000	200,000
Investment in low-income housing limited partnership	$ 3,904,000	4,545,000
Income tax credits and adjustments period	10 years
Accrued benefit liability	$ 1,117,000	1,081,000
Other postretirement benefit	36,000	38,000
Advertising expense	312,000	294,000
Shareholder Service [Member]
Summary of Significant Accounting Policies [Line Items]
Trust and Estate fees recognized	$ 88,000	$ 95,000
Leasehold Improvements [Member]
Summary of Significant Accounting Policies [Line Items]
Estimated useful life of property and equipment, description	shorter of the assets' useful life or the related lease term
Residential Portfolio Segment [Member] \| Credit Exposure [Member]
Summary of Significant Accounting Policies [Line Items]
Percentage of capital representing credit exposure to lessors	32.00%
Residential Portfolio Segment [Member] \| Mortgage Loan [Member]
Summary of Significant Accounting Policies [Line Items]
Loan period for lending, maximum	25 years
Maximum loan-to-value ratio	80.00%
Residential Portfolio Segment [Member] \| Home Equity Lines of Credit [Member]
Summary of Significant Accounting Policies [Line Items]
Loan period for lending, maximum	20 years
Maximum loan-to-value ratio	90.00%
Residential Portfolio Segment [Member] \| Home Equity Installments [Member]
Summary of Significant Accounting Policies [Line Items]
Loan period for lending, maximum	15 years
Maximum loan-to-value ratio	80.00%
Real Estate Portfolio Segment [Member] \| Credit Exposure [Member]
Summary of Significant Accounting Policies [Line Items]
Percentage of capital representing credit exposure to lessors	26.00%
Real Estate Portfolio Segment [Member] \| Mortgage Loan [Member]
Summary of Significant Accounting Policies [Line Items]
Loan period for lending, maximum	25 years
Real Estate Portfolio Segment [Member] \| Commercial Loan [Member]
Summary of Significant Accounting Policies [Line Items]
Loan period for lending, maximum	20 years
Maximum loan-to-value ratio	80.00%
Commercial Portfolio Segment [Member] \| Credit Exposure [Member]
Summary of Significant Accounting Policies [Line Items]
Percentage of capital representing credit exposure to lessors	30.00%
Non-Residential Portfolio [Member] \| Credit Exposure [Member]
Summary of Significant Accounting Policies [Line Items]
Percentage of capital representing credit exposure to lessors	45.00%
Maximum [Member] \| Furniture and Equipment [Member]
Summary of Significant Accounting Policies [Line Items]
Estimated useful life of property and equipment	10 years
Maximum [Member] \| Building [Member]
Summary of Significant Accounting Policies [Line Items]
Estimated useful life of property and equipment	50 years
Minimum [Member] \| Furniture and Equipment [Member]
Summary of Significant Accounting Policies [Line Items]
Estimated useful life of property and equipment	3 years
Minimum [Member] \| Building [Member]
Summary of Significant Accounting Policies [Line Items]
Estimated useful life of property and equipment	25 years

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Maximum Loan To Value Ratio

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Summary of Significant Accounting Policies [Line Items]

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Amount charged to advertising expense for the period, which are expenses incurred with the objective of increasing revenue for a specified brand, product or product line.

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Identifies or describes the benchmark that serves as the denominator in the calculation of the percentage of concentration risk.

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For an entity that discloses a concentration risk in relation to quantitative amount, which serves as the "benchmark" (or denominator) in the equation, this concept represents the concentration percentage derived from the division.

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The carrying amount of the liability as of the balance sheet date to an individual under a deferred compensation arrangement. This amount may be the result of periodic accruals made over the period of active employment, or reflect termination benefits resulting contractual terms or a death benefit.

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Amount of investment in equity security without readily determinable fair value.

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Amount of loss from the write-down of an asset representing the future economic benefits arising from other assets acquired in a business combination that are not individually identified and separately recognized.

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Amount of investment in debt security measured at amortized cost (held-to-maturity).

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Period of time between issuance and maturity of customer deposits, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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Amount after accumulated amortization of finite-lived and indefinite-lived intangible assets classified as other.

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Amount of cost (reversal of cost) for other postretirement benefits. Excludes pension benefits.

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Useful life of long lived, physical assets used in the normal conduct of business and not intended for resale, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days. Examples include, but not limited to, land, buildings, machinery and equipment, office equipment, furniture and fixtures, and computer equipment.

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