Registration of securities issued in business combination transactions

Warrants (Schedule Of Assumptions Used In Calculating Fair Value Of Warrants) (Details)

v3.20.2
Warrants (Schedule Of Assumptions Used In Calculating Fair Value Of Warrants) (Details) - $ / shares
 3 Months Ended 12 Months Ended
Mar. 31, 2020
Dec. 31, 2019
Dec. 31, 2018
Class of Warrant or Right [Line Items]      
Trading market prices $ 1.80 $ 1.91 $ 11.16
Estimated future volatility 100.00% 102.00% 105.00%
Dividend
Fundamental transaction likelihood 50.00% 50.00% 5.00%
Fundamental transaction timing 2020-07 2020-04  
Fundamental transaction timing     End of warrant term
Minimum [Member]      
Class of Warrant or Right [Line Items]      
Estimated future risk-free rate 0.20% 1.57% 2.35%
Equivalent volatility 113.00% 85.00% 99.00%
Equivalent risk-free rate 0.13% 1.57% 2.51%
Maximum [Member]      
Class of Warrant or Right [Line Items]      
Estimated future risk-free rate 0.41% 1.72% 2.53%
Equivalent volatility 129.00% 94.00% 104.00%
Equivalent risk-free rate 0.19% 1.59% 2.55%