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Share-Based Compensation (Summary Of Performance Share Units Grant-Date Fair Values And Their Related Assumptions) (Details) - Performance Share Units [Member]
9 Months Ended
Sep. 30, 2015
$ / shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]  
Granted, weighted average grant-date fair value $ 84.14
Risk-free interest rate 1.06%
Volatility factor 26.20%
Contractual term (in years) 2 years 10 months 21 days
Minimum [Member]  
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]  
Granted, weighted average grant-date fair value $ 81.99
Maximum [Member]  
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]  
Granted, weighted average grant-date fair value $ 85.05