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Stock Compensation (Summary Of Other Information Concerning Stock Options) (Details) - Stock Options [Member] - USD ($)
12 Months Ended
Dec. 31, 2017
Dec. 31, 2016
Dec. 31, 2015
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Weighted-average fair value of options granted $ 5.97 $ 3.68 $ 3.82
Intrinsic value of options exercised $ 4,748,000 $ 2,422,000 $ 761,000