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Stock Compensation Plans - Assumptions Used to Estimate The Fair Value of The Performance-based Stock Options and Restricted Stock Units (Details)
12 Months Ended
Dec. 31, 2018
Dec. 31, 2017
Dec. 31, 2016
Fair Value, Option, Quantitative Disclosures [Line Items]      
Expected volatility 45.00% 45.20%  
Employee Stock Option      
Fair Value, Option, Quantitative Disclosures [Line Items]      
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Risk Free Interest Rate 2.65%    
Risk-free interest rate, minimum   1.88% 1.06%
Risk-free interest rate, maximum   2.02% 1.57%
Expected dividend yield 0.00% 0.00% 0.00%
Expected option life 4 years 5 years 4 years
Weighted-average expected volatility 45.00% 45.20% 46.10%
Performance Shares      
Fair Value, Option, Quantitative Disclosures [Line Items]      
Risk-free interest rate, minimum     0.95%
Risk-free interest rate, maximum     1.48%