Stock-based Compensation (Narrative) (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares authorized for issuance	1,500,000
Stock option expense	$ 3,144	$ 3,006	$ 2,340
Share-Based Compensation	$ 3,144	$ 3,006	$ 2,339
Restricted Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares granted	36,812	35,000	31,277
Shares granted, weighted average grant date market value		$ 49.79	$ 49.55
Amortization of restricted stock bonus	$ 1,551	$ 1,571	$ 1,743
Total unrecognized compensation expense	$ 1,438
Total unrecognized compensation expense, weighted average period	1 year 25 days
Total fair value of shares vested	$ 527	$ 1,112	$ 1,389
Fair value of granted shares per share	$ 49.30
Performance-based restricted shares [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares granted	36,801	35,602	30,388
Vesting period	3 years	3 years	3 years
Fair value of granted shares per share	$ 49.06	$ 49.04	$ 49.33
Expense incurred to grant shares	$ 593
Percentage of financial goal	108.00%
Performance-based restricted shares [Member] \| Minimum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Percentage of target opportunity for awards to vest	0.00%	0.00%	0.00%
Performance-based restricted shares [Member] \| Maximum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Percentage of target opportunity for awards to vest	150.00%	150.00%	150.00%
Performance-based restricted shares [Member] \| Transaction One [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expense incurred to grant shares	$ 583
Percentage of financial goal	118.00%
Performance-based restricted shares [Member] \| Transaction Two [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expense incurred to grant shares	$ 674
Percentage of financial goal	117.00%
SARs [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total unrecognized compensation expense	$ 0
Total intrinsic value of options exercised	$ 2,022	$ 1,110
Average remaining contractual term	2 years 11 months 1 day	3 years 6 months
Outstanding, Aggregate Intrinsic Value	$ 3,908	$ 5,468
Share-Based Compensation	$ 0

Amount of amortization of the restricted stock bonus.

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Percentage of financial goals.

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Percentage of target opportunity for awards to vest.

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Amount of cost not yet recognized for nonvested award under share-based payment arrangement.

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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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The cash outflow for cost incurred directly with the issuance of an equity security.

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Amount of noncash expense for share-based payment arrangement.

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Period over which grantee's right to exercise award under share-based payment arrangement is no longer contingent on satisfaction of service or performance condition, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents reported fact of one year, five months, and thirteen days. Includes, but is not limited to, combination of market, performance or service condition.

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The number of grants made during the period on other than stock (or unit) option plans (for example, phantom stock or unit plan, stock or unit appreciation rights plan, performance target plan).

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The weighted average fair value at grant date for nonvested equity-based awards issued during the period on other than stock (or unit) option plans (for example, phantom stock or unit plan, stock or unit appreciation rights plan, performance target plan).

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Weighted average remaining contractual term for equity-based awards excluding options, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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Number of shares authorized for issuance under share-based payment arrangement.

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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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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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Amount by which the current fair value of the underlying stock exceeds the exercise price of options outstanding.

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Fair value of options vested. Excludes equity instruments other than options, for example, but not limited to, share units, stock appreciation rights, restricted stock.

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Amount of noncash expense for option under share-based payment arrangement.

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