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Stock Based Compensation (Schedule of Outstanding Stock Options) (Details) - $ / shares | 12 Months Ended |  |
--- | --- | --- | ---
Dec. 31, 2020 | Dec. 31, 2019 | Dec. 31, 2018
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |
Options Outstanding | 215,970 | 199,825 | 208,700
Average Exercise Price | $ 25.73 | $ 24.78 | $ 22.54
Remaining Life, Years | 6 years |  |
Options Exercisable | 182,220 | 173,075 |
Average Exercise Price | $ 25.51 | $ 23.04 |
Average Exercise Price - $16.65 [Member] |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |
Options Outstanding | 18,000 |  |
Average Exercise Price | $ 16.65 |  |
Remaining Life, Years | 1 year |  |
Options Exercisable | 18,000 |  |
Average Exercise Price | $ 16.65 |  |
Average Exercise Price - $18.03 [Member] |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |
Options Outstanding | 23,100 |  |
Average Exercise Price | $ 18.03 |  |
Remaining Life, Years | 2 years |  |
Options Exercisable | 23,100 |  |
Average Exercise Price | $ 18.03 |  |
Average Exercise Price - $18.36 [Member] |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |
Options Outstanding | 1,650 |  |
Average Exercise Price | $ 18.36 |  |
Remaining Life, Years | 2 years |  |
Options Exercisable | 1,650 |  |
Average Exercise Price | $ 18.36 |  |
Average Exercise Price - $19.30 [Member] |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |
Options Outstanding | 3,000 |  |
Average Exercise Price | $ 19.30 |  |
Remaining Life, Years | 2 years 9 months 18 days |  |
Options Exercisable | 3,000 |  |
Average Exercise Price | $ 19.30 |  |
Average Exercise Price - $17.93 [Member] |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |
Options Outstanding | 20,125 |  |
Average Exercise Price | $ 17.93 |  |
Remaining Life, Years | 3 years |  |
Options Exercisable | 20,125 |  |
Average Exercise Price | $ 17.93 |  |
Average Exercise Price - $19.39 [Member] |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |
Options Outstanding | 8,250 |  |
Average Exercise Price | $ 19.39 |  |
Remaining Life, Years | 3 years 10 months 24 days |  |
Options Exercisable | 8,250 |  |
Average Exercise Price | $ 19.39 |  |
Average Exercise Price - $19.03 [Member] |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |
Options Outstanding | 9,375 |  |
Average Exercise Price | $ 19.03 |  |
Remaining Life, Years | 4 years 10 months 24 days |  |
Options Exercisable | 9,375 |  |
Average Exercise Price | $ 19.03 |  |
Average Exercise Price - $22.37 [Member] |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |
Options Outstanding | 16,120 |  |
Average Exercise Price | $ 22.37 |  |
Remaining Life, Years | 6 years |  |
Options Exercisable | 16,120 |  |
Average Exercise Price | $ 22.37 |  |
Average Exercise Price - $32.81 [Member] |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |
Options Outstanding | 29,500 |  |
Average Exercise Price | $ 32.81 |  |
Remaining Life, Years | 7 years |  |
Options Exercisable | 29,500 |  |
Average Exercise Price | $ 32.81 |  |
Average Exercise Price - $32.34 [Member] |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |
Options Outstanding | 26,350 |  |
Average Exercise Price | $ 32.34 |  |
Remaining Life, Years | 8 years |  |
Options Exercisable | 26,350 |  |
Average Exercise Price | $ 32.34 |  |
Average Exercise Price - $36.02 [Member] |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |
Options Outstanding | 26,750 |  |
Average Exercise Price | $ 36.02 |  |
Remaining Life, Years | 9 years |  |
Options Exercisable | 26,750 |  |
Average Exercise Price | $ 36.02 |  |
Average Exercise Price - $26.93 [Member] |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |
Options Outstanding | 33,750 |  |
Average Exercise Price | $ 26.93 |  |
Remaining Life, Years | 10 years |  |

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