Quarterly report pursuant to Section 13 or 15(d)

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

v3.10.0.1
Stock-Based Compensation - Weighted-Average Assumptions Used to Estimate Fair Value of Options Granted (Details) - $ / shares
3 Months Ended 9 Months Ended
Sep. 30, 2018
Sep. 30, 2017
Sep. 30, 2018
Sep. 30, 2017
Non-Employee        
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]        
Volatility (percent)   74.39%   76.06%
Risk free interest rate (percent)   2.17%   2.19%
Dividend yield (percent)   0.00%   0.00%
Term   6 years 7 months 21 days   6 years 10 months 21 days
Stock options        
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]        
Volatility (percent) 76.89% 75.28% 77.69% 74.60%
Risk free interest rate (percent) 2.76% 1.92% 2.88% 1.97%
Dividend yield (percent) 0.00% 0.00% 0.00% 0.00%
Term 6 years 3 months 26 days 5 years 8 months 23 days 6 years 5 months 19 days 5 years 10 months 24 days
Weighted-average fair value of options granted during the period (usd per share) $ 0.72 $ 1.91 $ 0.64 $ 1.89