Quarterly report pursuant to Section 13 or 15(d)

Warrant Liability - Assumptions Used and Summary of Warrant Liability (Details)

v3.19.3
Warrant Liability - Assumptions Used and Summary of Warrant Liability (Details) - Warrant - $ / shares
1 Months Ended 9 Months Ended 12 Months Ended
Apr. 30, 2019
Mar. 31, 2019
Jun. 30, 2018
Feb. 28, 2018
Feb. 28, 2017
Sep. 30, 2019
Dec. 31, 2018
Number of Shares Under Warrant              
Number of Shares Under Warrant, balance at beginning of period (shares)           3,426,711  
Number of shares under warrants granted (shares) 5,250,000 1,585,500 742,991 2,273,700 404,002 8,242,500  
Number of shares under warrant, exercised (in shares)           (1,413,018)  
Number of shares under warrant, expired (in shares)           0  
Number of Shares Under Warrant, balance at end of period (shares)           10,256,193 3,426,711
Number of Shares Under Warrant, Vested and Exercisable at end of period (in shares)           10,256,193  
Weighted Average Exercise Price              
Range of Warrant Price per Share, Outstanding, beginning of period (in dollars per share)           $ 2.48  
Range of Warrant Price Per Share, Granted (in dollars per share)           1.51  
Range of Warrant Price Per Share, Exercised (in dollars per share)           1.10  
Range of Warrant Price per Share, Outstanding, end of period (in dollars per share)           1.89 $ 2.48
Range of Warrant Price Per Share, Vested and Exercisable at end of period (in dollars per share)           $ 1.89  
Weighted Average Remaining Contractual Life              
ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsOutstandingWeightedAverageRemainingContractualTerms           4 years 3 months 14 days 4 years 6 months 10 days
ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsOutstandingWeightedAverageRemainingContractualTerms           4 years 3 months 14 days 4 years 6 months 10 days
Weighted Average Remaining Contractual Life, Vested and Exercisable at end of period (in years)           4 years 3 months 14 days  
Fair Value Assumptions and Methodology              
Expected dividend yield (percent)           0.00% 0.00%
Minimum              
Weighted Average Exercise Price              
Range of Warrant Price per Share, Outstanding, beginning of period (in dollars per share)           $ 1.50  
Range of Warrant Price Per Share, Granted (in dollars per share)           1.10  
Range of Warrant Price Per Share, Exercised (in dollars per share)           1.10  
Range of Warrant Price per Share, Outstanding, end of period (in dollars per share)           1.10 $ 1.50
Range of Warrant Price Per Share, Vested and Exercisable at end of period (in dollars per share)           $ 1.10  
Fair Value Assumptions and Methodology              
Risk fee interest rate (percent)           1.55% 2.46%
Volatility (percent)           90.00% 75.00%
Expected life (years)           2 years 4 months 13 days 3 years 1 month 13 days
Maximum              
Weighted Average Exercise Price              
Range of Warrant Price per Share, Outstanding, beginning of period (in dollars per share)           $ 2.80  
Range of Warrant Price Per Share, Granted (in dollars per share)           1.75  
Range of Warrant Price Per Share, Exercised (in dollars per share)           1.50  
Range of Warrant Price per Share, Outstanding, end of period (in dollars per share)           2.80 $ 2.80
Range of Warrant Price Per Share, Vested and Exercisable at end of period (in dollars per share)           $ 2.80  
Fair Value Assumptions and Methodology              
Risk fee interest rate (percent)           1.60% 2.51%
Volatility (percent)           97.50% 80.00%
Expected life (years)           4 years 6 months 25 days 4 years 11 months 23 days