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Stock-Based Compensation (Options Value Assumptions) (Details) - Stock Options
6 Months Ended
Jun. 30, 2017
$ / shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]  
Risk-free interest rate (percent) 1.90%
Weighted average historical volatility (percent) 22.90%
Dividend yield (percent) 7.30%
Expected years until exercise (years) 4 years 5 months 28 days
Weighted average fair value of options granted (USD per share) $ 4.31