Quarterly report pursuant to Section 13 or 15(d)

Stock-Based Compensation - Weighted-Average Assumptions Used to Estimate Fair Value of Options Granted (Details)

v3.19.3
Stock-Based Compensation - Weighted-Average Assumptions Used to Estimate Fair Value of Options Granted (Details) - Stock Options - $ / shares
3 Months Ended 9 Months Ended
Sep. 30, 2019
Sep. 30, 2018
Sep. 30, 2019
Sep. 30, 2018
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]        
Volatility (percent) 94.57% 76.89% 93.86% 77.69%
Risk free interest rate (percent) 1.84% 2.76% 1.95% 2.88%
Dividend yield (percent) 0.00% 0.00% 0.00% 0.00%
Term (years) 5 years 3 months 6 days 6 years 3 months 25 days 5 years 5 months 9 days 6 years 5 months 20 days
Weighted-average fair value of options granted during the period (usd per share) $ 3.23 $ 21.60 $ 4.32 $ 19.20