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Stock-Based Compensation (Nature Of Total Stock-Based Compensation) (Details) - USD ($)
$ in Thousands
3 Months Ended
Mar. 31, 2019
Mar. 31, 2018
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]    
Employee Service Share-based Compensation, Allocation of Recognized Period Costs, Capitalized Amount $ (356) $ (471)
Stock-based compensation 12,462 12,978
Restricted Stock Units [Member]    
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]    
Stock-based compensation 8,609 9,287
Performance Shares [Member]    
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]    
Stock-based compensation 3,038 3,113
Employee Stock Purchase Plan [Member]    
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]    
Stock-based compensation $ 1,171 $ 1,049