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Stock-based Compensation - Schedule of Assumptions Used to Calculate Fair Value of Stock Options (Details)
12 Months Ended
Dec. 31, 2018
Dec. 31, 2017
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]    
Expected life (in years) 5 years 7 months 24 days 6 years 1 month 24 days
Risk-free interest rates 2.85% 2.03%
Volatility 75.51% 66.01%
Dividend yield 0.00% 0.00%