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Stock-Based Compensation (Details)
12 Months Ended
Dec. 31, 2017
Dec. 31, 2016
Dec. 31, 2015
Stock Based Compensation [Line Items]      
Expected dividends 0.00% 0.00% 0.00%
Risk free rate 1.56% 1.14% 1.11%
Minimum      
Stock Based Compensation [Line Items]      
Expected volatility 58.00% 68.00% 52.70%
Expected term (in years) 3 years 2 months 12 days 3 years 1 month 6 days 3 years 2 months 12 days
Maximum      
Stock Based Compensation [Line Items]      
Expected volatility 69.70% 71.30% 68.30%
Expected term (in years) 3 years 3 months 18 days 3 years 3 months 18 days 3 years 3 months 18 days