Share Based Compensation (Share Based Compensation Plans) (Details) - shares |
12 Months Ended | ||
|---|---|---|---|
Dec. 31, 2020 |
Dec. 31, 2019 |
Dec. 31, 2018 |
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| Share-based Payment Arrangement [Abstract] | |||
| Restricted stock awards granted (in shares) | 167,650 | 149,950 | 121,850 |
| Restricted stock awards forfeited (in shares) | 0 | (4,230) | 0 |
| Director stock awards granted (in shares) | 2,375 | 2,125 | 2,875 |
| Stock Option Activities: | |||
| Outstanding as of the beginning of year (in shares) | 1,454,074 | 1,467,391 | 1,546,014 |
| Granted (in shares) | 175,800 | 165,650 | 142,550 |
| Exercised (in shares) | (123,829) | (165,893) | (220,694) |
| Forfeited (in shares) | 0 | (5,200) | 0 |
| Expired (in shares) | (5,986) | (7,874) | (479) |
| Outstanding as of the end of year (in shares) | 1,500,059 | 1,454,074 | 1,467,391 |
| Employee Stock Purchase Plans shares issued (in shares) | 62,161 | 44,383 | 45,251 |
| Shares available for issuance under Share Incentive and Employee Stock Purchase Plans as of the end of year (in shares) | 1,037,414 | 539,414 | 884,218 |
| X | ||||||||||
- References No definition available.
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| X | ||||||||||
- Definition The difference between the maximum number of shares (or other type of equity) authorized for issuance under the plan (including the effects of amendments and adjustments), and the sum of: 1) the number of shares (or other type of equity) already issued upon exercise of options or other equity-based awards under the plan; and 2) shares (or other type of equity) reserved for issuance on granting of outstanding awards, net of cancellations and forfeitures, if applicable. Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
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- Definition Number of options or other stock instruments for which the right to exercise has lapsed under the terms of the plan agreements. Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
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- Definition The number of shares under options that were cancelled during the reporting period as a result of occurrence of a terminating event specified in contractual agreements pertaining to the stock option plan. Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
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- Definition Gross number of share options (or share units) granted during the period. No definition available.
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- Definition Number of options outstanding, including both vested and non-vested options. Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
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- Definition A roll forward is a reconciliation of a concept from the beginning of a period to the end of a period. No definition available.
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| X | ||||||||||
- Definition Number of shares issued during the period as a result of an employee stock purchase plan. Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
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- Definition Number of shares issued in lieu of cash for services contributed to the entity. Number of shares includes, but is not limited to, shares issued for services contributed by vendors and founders. No definition available.
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- Definition Number of shares related to Restricted Stock Award forfeited during the period. Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
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| X | ||||||||||
- Definition Total number of shares issued during the period, including shares forfeited, as a result of Restricted Stock Awards. Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
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| X | ||||||||||
- Definition Number of share options (or share units) exercised during the current period. Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
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