Quarterly report pursuant to Section 13 or 15(d)

Stock-based Compensation - Weighted Average Assumptions (Details)

v3.19.2
Stock-based Compensation - Weighted Average Assumptions (Details) - Stock Options [Member]
3 Months Ended 6 Months Ended
Jun. 30, 2019
Jun. 30, 2018
Jun. 30, 2019
Jun. 30, 2018
Stock-based awards weighted average assumptions [Abstract]        
Dividend yield 0.00% 0.00% 0.00% 0.00%
Expected volatility 102.00% 102.00% 103.00% 101.00%
Risk-free interest rate 2.21% 2.98% 2.51% 2.71%
Expected term 5 years 7 months 6 days 5 years 6 months 18 days 5 years 7 months 6 days 5 years 7 months 6 days