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Summary of Significant Accounting Policies Compensation (Details) - $ / shares
12 Months Ended
Dec. 31, 2016
Dec. 31, 2015
Dec. 31, 2014
Summary of Significant Accounting Policies [Abstract]      
Common Stock, Par or Stated Value Per Share $ 0.01 $ 0.01  
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Expected Volatility Rate 26.30% 26.60% 27.00%
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Expected Term 5 years 5 years 5 years
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Expected Dividend Rate 3.04% 3.13% 3.78%
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Risk Free Interest Rate 1.27% 1.29% 1.50%
Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Weighted Average Grant Date Fair Value $ 13.02 $ 13.68 $ 9.12
Historical Volatility Period Basis 10 years