Quarterly report pursuant to Section 13 or 15(d)

Stock-based Compensation - Valuation Assumptions (Details)

v3.19.2
Stock-based Compensation - Valuation Assumptions (Details)
3 Months Ended 6 Months Ended
Jun. 30, 2019
Jun. 30, 2018
Jun. 30, 2019
Jun. 30, 2018
Fair Value Measurement Inputs and Valuation Techniques [Line Items]        
Dividend yield 0.00% 0.00% 0.00% 0.00%
Risk-free interest rate 2.09% 2.85% 2.12%  
Expected term (in years) 6 years   6 years  
Volatility 102.00% 89.00% 102.00% 89.00%
Minimum        
Fair Value Measurement Inputs and Valuation Techniques [Line Items]        
Risk-free interest rate       2.70%
Expected term (in years)   6 years   6 years
Maximum        
Fair Value Measurement Inputs and Valuation Techniques [Line Items]        
Risk-free interest rate       2.97%
Expected term (in years)   10 years   10 years