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Equity-Based Compensation (Weighted Average Assumptions Used to Measure Fair Value of Stock Options) (Details)
12 Months Ended
Dec. 31, 2017
$ / shares
Share-based Payment Arrangement [Abstract]  
Fair Value $ 12.85
Expected Life (in years) 4 years
Expected Stock Volatility 35.70%
Risk-free Interest Rate 1.70%
Expected Dividend Yield 0.00%