Annual report pursuant to Section 13 and 15(d)

Note 7 - Stockholders' Equity (Details Textual)

v3.23.1
Note 7 - Stockholders' Equity (Details Textual) - USD ($)
 1 Months Ended 3 Months Ended 12 Months Ended
Mar. 25, 2022
Mar. 31, 2021
Feb. 28, 2021
Jan. 31, 2021
Dec. 31, 2022
Dec. 31, 2022
Dec. 31, 2021
Sep. 03, 2021
Aug. 01, 2018
Dec. 31, 2015
Preferred Stock, Shares Authorized (in shares)         10,000,000 10,000,000 10,000,000   10,000,000.0 5,000,000
Preferred Stock, Par or Stated Value Per Share (in dollars per share)         $ 0.001 $ 0.001 $ 0.001   $ 0.001 $ 0.001
Total Capital, Shares Authorized                 110,000,000.0  
Common Stock, Shares Authorized (in shares)         100,000,000 100,000,000 100,000,000      
Common Stock, Par or Stated Value Per Share (in dollars per share)         $ 0.001 $ 0.001 $ 0.001      
Stock Issued During Period, Shares, New Issues           10,323        
Proceeds From Issuance of Common Stock, Net of Issuance Costs           $ 320,000 $ 33,390,000      
Payments of Stock Issuance Costs           $ 1,397,000        
Tumim [Member]                    
Common Stock, Maximum Shares Sold 10,000,000                  
Warrants Issued With Placement Agent Agreement [Member]                    
Class of Warrants and Rights, Number of Securities Called by Warrants or Rights, Percentage of Total Common Stock Issuable Upon Conversion of Preferred Shares         14.50% 14.50%        
Subscription Agreements [Member]                    
Payments of Stock Issuance Costs         $ 1,400,000          
Subscription Agreements [Member] | Securities Purchase Agreement [Member]                    
Percentage of Proceeds from Issuance of Equity to Redeem Debt Outstanding         50.00%          
Proceeds from Issuance of Preferred Stock Used in Connection With Redemption of Debt         $ 4,200,000 $ 3,621,000        
Placement Agency Agreement [Member]                    
Aggregate Amount Required in Equity Offering for Agent Having Right to Appoint         $ 10,000,000 $ 10,000,000        
Purchase Agreement [Member] | Tumim [Member]                    
Stock Issued During Period, Shares, New Issues 50,000         7,425        
Shares Issued, Price Per Share (in dollars per share)         $ 1.11 $ 1.11        
Stock Issued During Period, Value, New Issues $ 100,000                  
Proceeds From Issuance of Common Stock, Net of Issuance Costs           $ 8,000        
Common Stock, Maximum Shares Allowed to Issue and Sell, Initial 7,361,833                  
Common Stock, Maximum Shares Allowed to Issue and Sell, Percentage of Shares Issued and Outstanding, Initial 19.99%                  
Common Stock, Price Per Share, Percentage of Weighted Average Price 95.00%                  
Purchase Agreement [Member] | Tumim [Member] | Minimum [Member]                    
Beneficial Ownership, Minimum Percentage of Shares Outstanding, Initial 4.99%                  
Purchase Agreement [Member] | Tumim [Member] | Maximum [Member]                    
Beneficial Ownership, Minimum Percentage of Shares Outstanding, Initial 9.99%                  
January 2021 Offering [Member]                    
Stock Issued During Period, Shares, New Issues       3,076,924            
Shares Issued, Price Per Share (in dollars per share)       $ 2.60            
Proceeds From Issuance of Common Stock, Net of Issuance Costs       $ 8,000,000.0            
Payments of Stock Issuance Costs       $ 73,000            
February 2021 Offering [Member]                    
Stock Issued During Period, Shares, New Issues     2,926,830              
Shares Issued, Price Per Share (in dollars per share)     $ 4.10              
Proceeds From Issuance of Common Stock, Net of Issuance Costs     $ 12,000,000.0              
Payments of Stock Issuance Costs     $ 70,000              
March 2021 Offering [Member]                    
Stock Issued During Period, Shares, New Issues   1,512,499                
Shares Issued, Price Per Share (in dollars per share)   $ 9.00                
Proceeds From Issuance of Common Stock, Net of Issuance Costs   $ 13,600,000                
Payments of Stock Issuance Costs   $ 72,000                
Sales Agreement [Member] | Agents [Member]                    
Stock Issued During Period, Shares, New Issues           323,639        
Shares Issued, Price Per Share (in dollars per share)         $ 0.99 $ 0.99        
Proceeds From Issuance of Common Stock, Net of Issuance Costs           $ 312,000        
Common Stock, Maximum Amount to Be Distributed Through Financial Institutions               $ 75,000,000    
Financial Institutions, Commission Rate               3.00%    
Series A Preferred Offerings [Member] | Subscription Agreements [Member]                    
Stock Issued During Period, Shares, New Issues         10,323          
Preferred Stock, Stated Value         $ 1,000 $ 1,000        
Preferred Stock, Beneficial Ownership Limitation, Minimum Percentage of Outstanding Preferred Stock Shares Required         51.00% 51.00%        
Preferred Stock, Beneficial Ownership Limitations, Percentage of Outstanding Shares Required to be Converted When Common Stock Volume-weighted Average Price Over Previous 10 Days as Reported Equals More Than 250% of Conversion Price         50.00% 50.00%        
Preferred Stock, Beneficial Ownership Limitations, Percentage of Outstanding Shares Required to be Converted When Common Stock Volume-weighted Average Price Over Previous 10 Days as Reported Equals More Than 300% of Conversion Price         100.00% 100.00%        
Preferred Stock Voting Exceptions, Minimum Amount of Indebtedness Required         $ 5,000,000 $ 5,000,000        
Preferred Stock Dividends, Percentage of Common Shares         20.00% 20.00%        
Series A Preferred Offerings [Member] | Placement Agency Agreement [Member]                    
Placement Fee, Percentage of Proceeds from Issuance of Equity         10.00%          
Nonaccountable Expense, Percentage of Proceeds from Issuance of Equity         3.00%          
Series A Preferred Stock [Member]                    
Stock Issued During Period, Shares, New Issues           5,359        
Payments of Stock Issuance Costs           $ 752,000        
Series A Preferred Stock [Member] | Subscription Agreements [Member]                    
Preferred Stock, Par or Stated Value Per Share (in dollars per share)         $ 0.001 $ 0.001        
Shares Issued, Price Per Share (in dollars per share)         1,000 $ 1,000        
Series A-2 Preferred Stock [Member]                    
Stock Issued During Period, Shares, New Issues           1,297        
Payments of Stock Issuance Costs           $ 169,000        
Series A-2 Preferred Stock [Member] | Subscription Agreements [Member]                    
Preferred Stock, Par or Stated Value Per Share (in dollars per share)         0.001 $ 0.001        
Shares Issued, Price Per Share (in dollars per share)         1,000 $ 1,000        
Series A-3 Preferred Stock [Member]                    
Stock Issued During Period, Shares, New Issues           1,733        
Payments of Stock Issuance Costs           $ 225,000        
Series A-3 Preferred Stock [Member] | Subscription Agreements [Member]                    
Preferred Stock, Par or Stated Value Per Share (in dollars per share)         0.001 $ 0.001        
Shares Issued, Price Per Share (in dollars per share)         1,000 $ 1,000        
Series A-4 Preferred Stock [Member]                    
Stock Issued During Period, Shares, New Issues           1,934        
Payments of Stock Issuance Costs           $ 251,000        
Series A-4 Preferred Stock [Member] | Subscription Agreements [Member]                    
Preferred Stock, Par or Stated Value Per Share (in dollars per share)         0.001 $ 0.001        
Shares Issued, Price Per Share (in dollars per share)         $ 1,000 $ 1,000