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Share-Based Compensation Schedule Of Performance Share Unit Transactions (Details) - Performance Share Units [Member] - $ / shares
9 Months Ended
Sep. 30, 2017
Sep. 30, 2016
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number of Shares [Roll Forward]    
Unvested balance at beginning of period 1,027,280  
Shares granted 405,014  
Shares vested (215,439)  
Shares forfeited (17,519)  
Unvested balance at end of period 1,199,336  
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Additional Disclosures [Abstract]    
Weighted average grant date fair value, beginning of period $ 17.24  
Weighted average grant date fair value, grants 16.90 $ 10.16
Weighted average grant date fair value, vested 31.63  
Weighted average grant date fair value, forfeited 13.88  
Weighted average grant date fair value, end of period $ 14.59