Annual report pursuant to Section 13 and 15(d)

Stock-Based Compensation - Valuation Assumptions (Details)

v3.19.1
Stock-Based Compensation - Valuation Assumptions (Details) - $ / shares
12 Months Ended
Dec. 31, 2018
Dec. 31, 2017
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]    
Expected dividend yield 0.00%  
Employee Grants    
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]    
Volatility 82.00% 138.90%
Expected term (in years) 6 years 6 years
Risk-free rate 2.24% 2.00%
Expected dividend yield 0.00% 0.00%
Weighted average grant date fair value per share (in dollars per share) $ 2.22 $ 2.05