Quarterly report pursuant to Section 13 or 15(d)

Note 8 - Subsequent Events (Details Textual)

v3.20.2
Note 8 - Subsequent Events (Details Textual) - USD ($)
1 Months Ended 3 Months Ended 9 Months Ended
Nov. 12, 2020
Oct. 31, 2020
Sep. 30, 2020
Jun. 30, 2020
Mar. 31, 2020
Sep. 30, 2019
Jun. 30, 2019
Mar. 31, 2019
Sep. 30, 2020
Sep. 30, 2019
Jul. 31, 2020
Proceeds from Issuance of Common Stock                 $ 17,077,000 $ 19,292,000  
Stock Issued During Period, Value, New Issues     $ 1,780,000 $ 10,007,000 $ 566,000 $ 52,000 $ 3,584,000 $ 3,226,000      
Lincoln Park [Member]                      
Stock Issued During Period, Value, New Issues               $ 883,000      
Subsequent Event [Member] | Lincoln Park [Member]                      
Stock Issued During Period, Shares, New Issues (in shares) 2,829,214                    
Purchase Agreement, Common Stock, Maximum Aggregate Commitment $ 22.0                    
Stock Issued During Period, Shares, Commitment Consideration (in shares) 760,194                    
Purchase Agreement, Maximum Aggregate Commitment, Number of Additional Shares Issued (in shares) 304,077                    
Shares Issued, Price Per Share (in dollars per share) $ 0.707                    
Stock Issued During Period, Value, New Issues $ 2,000,000.0                    
Stock Issued During Period, Shares, Additional Commitment Shares (in shares) 27,643                    
The 2020 ATM Agreement [Member]                      
At Market Issuance Sales Agreement, Maximum Aggregate Offering Price                     $ 15,000,000.0
The 2020 ATM Agreement [Member] | Subsequent Event [Member]                      
Stock Issued During Period, Shares, New Issues (in shares)   700,339                  
Shares Issued, Average Price Per Share (in dollars per share)   $ 0.83                  
Proceeds from Issuance of Common Stock   $ 600,000                  
At Market Issuance Sales Agreement, Commission Fee, Percentage of Gross Proceeds   3.00%