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Stock Based Compensation (Schedule of Outstanding Stock Options) (Details) - $ / shares | 12 Months Ended |  |  |
--- | --- | --- | --- | ---
Dec. 31, 2016 | Dec. 31, 2015 | Dec. 31, 2014 | Dec. 31, 2013
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |  |
Options Outstanding | 160,429 | 194,521 | 206,463 | 219,540
Average Exercise Price | $ 27.37 | $ 26.91 | $ 26.74 | $ 26.64
Remaining Life, Years | 5 years 7 months 6 days |  |  |
Options Exercisable | 144,429 | 180,021 | 193,963 |
Average Exercise Price | $ 26.39 | $ 26.78 | $ 26.59 |
Average Exercise Price - $27.62 [Member] |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |  |
Options Outstanding | 12,650 |  |  |
Average Exercise Price | $ 28.41 |  |  |
Remaining Life, Years | 1 year |  |  |
Options Exercisable | 12,650 |  |  |
Average Exercise Price | $ 28.41 |  |  |
Average Exercise Price - $28.64 [Member] |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |  |
Options Outstanding | 13,200 |  |  |
Average Exercise Price | $ 25.00 |  |  |
Remaining Life, Years | 2 years |  |  |
Options Exercisable | 13,200 |  |  |
Average Exercise Price | $ 25.00 |  |  |
Average Exercise Price - $28.41 [Member] |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |  |
Options Outstanding | 12,650 |  |  |
Average Exercise Price | $ 25.99 |  |  |
Remaining Life, Years | 3 years |  |  |
Options Exercisable | 12,650 |  |  |
Average Exercise Price | $ 25.99 |  |  |
Average Exercise Price - $25.00 [Member] |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |  |
Options Outstanding | 1,100 |  |  |
Average Exercise Price | $ 24.44 |  |  |
Remaining Life, Years | 3 years 2 months 12 days |  |  |
Options Exercisable | 1,100 |  |  |
Average Exercise Price | $ 24.44 |  |  |
Average Exercise Price - $25.99 [Member] |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |  |
Options Outstanding | 15,229 |  |  |
Average Exercise Price | $ 25.25 |  |  |
Remaining Life, Years | 4 years |  |  |
Options Exercisable | 15,229 |  |  |
Average Exercise Price | $ 25.25 |  |  |
Average Exercise Price - $24.44 [Member] |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |  |
Options Outstanding | 19,800 |  |  |
Average Exercise Price | $ 24.97 |  |  |
Remaining Life, Years | 5 years |  |  |
Options Exercisable | 19,800 |  |  |
Average Exercise Price | $ 24.97 |  |  |
Average Exercise Price - $25.25 [Member] |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |  |
Options Outstanding | 21,450 |  |  |
Average Exercise Price | $ 27.05 |  |  |
Remaining Life, Years | 6 years |  |  |
Options Exercisable | 21,450 |  |  |
Average Exercise Price | $ 27.05 |  |  |
Average Exercise Price - $24.97 [Member] |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |  |
Options Outstanding | 1,100 |  |  |
Average Exercise Price | $ 27.55 |  |  |
Remaining Life, Years | 6 years |  |  |
Options Exercisable | 1,100 |  |  |
Average Exercise Price | $ 27.55 |  |  |
Average Exercise Price - $27.05 [Member] |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |  |
Options Outstanding | 2,000 |  |  |
Average Exercise Price | $ 28.95 |  |  |
Remaining Life, Years | 6 years 8 months 12 days |  |  |
Options Exercisable | 2,000 |  |  |
Average Exercise Price | $ 28.95 |  |  |
Average Exercise Price - $27.55 [Member] |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |  |
Options Outstanding | 21,250 |  |  |
Average Exercise Price | $ 26.90 |  |  |
Remaining Life, Years | 7 years |  |  |
Options Exercisable | 21,250 |  |  |
Average Exercise Price | $ 26.90 |  |  |
Average Exercise Price - $28.95 [Member] |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |  |
Options Outstanding | 10,000 |  |  |
Average Exercise Price | $ 29.08 |  |  |
Remaining Life, Years | 8 years |  |  |
Options Exercisable | 10,000 |  |  |
Average Exercise Price | $ 29.08 |  |  |
Average Exercise Price - $26.90 [Member] |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |  |
Options Outstanding | 14,000 |  |  |
Average Exercise Price | $ 28.55 |  |  |
Remaining Life, Years | 9 years |  |  |
Options Exercisable | 14,000 |  |  |
Average Exercise Price | $ 28.55 |  |  |
Average Exercise Price 29.08 [Member] |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |  |
Options Outstanding | 16,000 |  |  |
Average Exercise Price | $ 33.56 |  |  |
Remaining Life, Years | 10 years |  |  |
Options Exercisable | 0 |  |  |
Average Exercise Price | $ 0.00 |  |  |
Average Exercise Price - $28.55 [Member] |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |  |
Options Exercisable | 0 |  |  |
Average Exercise Price | $ 0.00 |  |  |

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