Employee Benefit Plans - SARs Outstanding by Exercise Price Range (Details) - Stock Appreciation Rights (SARs) [Member] - $ / shares	3 Months Ended
Mar. 31, 2021	Dec. 31, 2020
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Exercise Prices (in dollars per share)	$ 19.41	$ 19.02
Number Outstanding (in shares)	95,000	73,000
SARs Outstanding, Weighted Average Remaining Life	2 years 18 days
SARs Outstanding, Weighted Average Exercise Price (in dollars per share)	$ 19.41
SARs Exercisable, Number Exercisable (in shares)	34,000
SARs Exercisable, Weighted Average Exercise Price (in dollars per share)	$ 21.61
15.19 [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Exercise Prices (in dollars per share)	$ 15.19
Number Outstanding (in shares)	18,000
SARs Outstanding, Weighted Average Remaining Life	2 years 9 months
SARs Outstanding, Weighted Average Exercise Price (in dollars per share)	$ 15.19
18.12 [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Exercise Prices (in dollars per share)	$ 18.12
Number Outstanding (in shares)	21,000
SARs Outstanding, Weighted Average Remaining Life	1 year 9 months
SARs Outstanding, Weighted Average Exercise Price (in dollars per share)	$ 18.12
21.70 [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Exercise Prices (in dollars per share)	$ 20.70
Number Outstanding (in shares)	22,000
SARs Outstanding, Weighted Average Remaining Life	3 years 9 months 3 days
SARs Outstanding, Weighted Average Exercise Price (in dollars per share)	$ 20.70
21.61 [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Exercise Prices (in dollars per share)	$ 21.61
Number Outstanding (in shares)	34,000
SARs Outstanding, Weighted Average Remaining Life	9 months
SARs Outstanding, Weighted Average Exercise Price (in dollars per share)	$ 21.61
SARs Exercisable, Number Exercisable (in shares)	34,000
SARs Exercisable, Weighted Average Exercise Price (in dollars per share)	$ 21.61

The number of shares into which fully or partially vested stock options outstanding as of the balance sheet date can be currently converted under the option plan.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (c)(1)(iii)
-URI http://asc.fasb.org/extlink&oid=116856206&loc=d3e5070-113901

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Number of options outstanding, including both vested and non-vested options.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
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-Section 50
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Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
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-Paragraph 2
-Subparagraph (c)(1)(i)-(ii)
-URI http://asc.fasb.org/extlink&oid=116856206&loc=d3e5070-113901

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Weighted average price at which grantees can acquire the shares reserved for issuance under the stock option plan.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
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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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Weighted average exercise price as of the balance sheet date for those equity-based payment arrangements exercisable and outstanding.

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The weighted average price as of the balance sheet date at which grantees could acquire the underlying shares with respect to all outstanding stock options which are in the customized range of exercise prices.

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Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
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- Definition

Weighted average remaining contractual term of outstanding stock options, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
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