Annual report pursuant to Section 13 and 15(d)

Stockholders' Equity (Schedule of Stock Option Valuation Assumptions) (Details)

v3.19.1
Stockholders' Equity (Schedule of Stock Option Valuation Assumptions) (Details)
12 Months Ended
Dec. 31, 2018
Dec. 31, 2017
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]    
Dividend yield 0.00% 0.00%
Minimum [Member]    
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]    
Expected volatility 83.63% 76.35%
Risk-free interest rate 2.32% 1.86%
Expected term (years) 5 years 1 month 6 days 5 years 9 months 18 days
Maximum [Member]    
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]    
Expected volatility 121.81% 79.08%
Risk-free interest rate 2.98% 2.26%
Expected term (years) 6 years 3 months 19 days 7 years 9 months 18 days