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Stock-Based Compensation - Schedule of Share-based Payment Award, TSRs, Valuation Assumptions (Details) - TSR-based Performance Shares [Member]
12 Months Ended
Dec. 31, 2017
Dec. 31, 2016
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]    
Expected volatility 26.00% 27.60%
Dividend yield 0.00% 0.00%
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Expected Term 1 year 6 months 25 days 3 years
Fair Value Assumptions, Risk Free Interest Rate 1.83% 0.87%