Stock Based Compensation Schedule of Other Stock Option Plan Information (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Share-based Compensation Arrangement by Share-based Payment Award, Options, Additional Disclosures [Abstract]
Stock Options Granted (in shares)	52,324	55,167	56,722
Weighted Average Grant Date Information:
Fair Value of Options Granted, Weighted Average Grant Date (in dollars per share)	$ 4.84	$ 5.42	$ 5.27
Fair Value Assumptions:
Dividend Yield	2.90%	3.26%	2.98%
Expected Volatility	20.25%	22.58%	21.55%
Risk Free Interest Rate	1.53%	2.63%	2.68%
Expected Lives (in years)	6 years 8 months 4 days	8 years 8 months 4 days	6 years 11 months 23 days
Amount Expensed During the Year	$ 301	$ 316	$ 322
Compensation Costs for Non-vested Awards Not Yet Recognized	$ 440	$ 487	$ 504
Weighted Average Expected Vesting Period (in years)	2 years 2 months 1 day	2 years 25 days	2 years 8 months 26 days
Proceeds From Stock Options Exercised	$ 748	$ 1,792	$ 2,255
Tax Benefits Related to Stock Options Exercised	52	227	240
Intrinsic Value of Stock Options Exercised	$ 282	$ 1,073	$ 1,552

Weighted-average period over which cost not yet recognized is expected to be recognized for award under share-based payment arrangement, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents reported fact of one year, five months, and thirteen days.

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Amount of cost to be recognized for option under share-based payment arrangement.

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Amount of tax benefit from exercise of option under share-based payment arrangement.

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Amount of cash inflow from exercise of option under share-based payment arrangement.

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-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
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Amount of noncash expense for share-based payment arrangement.

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The estimated dividend rate (a percentage of the share price) to be paid (expected dividends) to holders of the underlying shares over the option's term.

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The estimated measure of the percentage by which a share price is expected to fluctuate during a period. Volatility also may be defined as a probability-weighted measure of the dispersion of returns about the mean. The volatility of a share price is the standard deviation of the continuously compounded rates of return on the share over a specified period. That is the same as the standard deviation of the differences in the natural logarithms of the stock prices plus dividends, if any, over the period.

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The risk-free interest rate assumption that is used in valuing an option on its own shares.

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Amount of accumulated difference between fair value of underlying shares on dates of exercise and exercise price on options exercised (or share units converted) into shares.

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Gross number of share options (or share units) granted during the period.

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The weighted average grant-date fair value of options granted during the reporting period as calculated by applying the disclosed option pricing methodology.

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Expected term of award under share-based payment arrangement, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents reported fact of one year, five months, and thirteen days.

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