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Stockholders' Equity (Schedule of Fair Value of Employee Stock Options) (Details)
12 Months Ended
Dec. 31, 2019
Dec. 31, 2018
Dec. 31, 2017
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]      
Dividend yield 0.00%    
Options outstanding [Member]      
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]      
Expected term in years   5 years 2 months 12 days 6 years 1 month 6 days
Expected volatility   66.80% 70.00%
Risk-free interest rate   2.60% 2.10%
Dividend yield