Note 9 - Stockholder's Equity (Details Textual) - $ / shares
 3 Months Ended 6 Months Ended
Apr. 08, 2020
Mar. 04, 2020
Jan. 08, 2020
Dec. 05, 2019
Oct. 08, 2019
Sep. 05, 2019
Jul. 10, 2019
Jun. 05, 2019
Apr. 18, 2019
Mar. 13, 2019
Feb. 22, 2019
May 22, 2017
Aug. 18, 2015
May 06, 2013
May 31, 2020
May 31, 2019
May 31, 2020
May 31, 2019
Common Stock, Dividends, Per Share, Declared (in dollars per share)                             $ 0.01 $ 0.04 $ 0.05
Preferred Stock Dividends Number of Rights Declared (in shares)                           1        
Preferred Stock Dividends Number of Rights Minimum Percent of Common Stock that must be Acquired to Make Rights Exercisable                           15.00%        
Preferred Stock Dividends Number of Rights Minimum Percent of Common Stock that Must be Acquired to Make Rights Exercisable, Institutional Investors                           20.00%        
Right to Purchase Series A Preferred Stock [Member]                                    
Class of Warrant or Right, Number of Securities Called by Each Warrant or Right (in shares)                           0.001        
Class of Warrant or Right, Exercise Price of Warrants or Rights (in dollars per share)                           $ 0.90        
Class of Warrant or Right, Term (Year)                     9 years 7 years 5 years          
Quarterly Dividend [Member]                                    
Common Stock, Dividends, Per Share, Declared (in dollars per share)   $ 0.01   $ 0.01   $ 0.01   $ 0.01   $ 0.01                
Common Stock, Dividends, Per Share, Cash Paid (in dollars per share) $ 0.01   $ 0.01   $ 0.01   $ 0.01   $ 0.01                  
Special Cash Distribution [Member]                                    
Common Stock, Dividends, Per Share, Declared (in dollars per share)       $ 0.02                            
Common Stock, Dividends, Per Share, Cash Paid (in dollars per share)     $ 0.02