Annual report pursuant to Section 13 and 15(d)

Note 9 - Stockholders' Equity (Details Textual)

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Note 9 - Stockholders' Equity (Details Textual) - USD ($)
 1 Months Ended 2 Months Ended 3 Months Ended 12 Months Ended
Aug. 09, 2019
Feb. 01, 2019
Dec. 31, 2019
May 31, 2019
Sep. 30, 2019
Dec. 31, 2020
Sep. 30, 2020
Jun. 30, 2020
Mar. 31, 2020
Dec. 31, 2020
Dec. 31, 2019
Mar. 20, 2020
May 16, 2019
Jan. 12, 2016
Jul. 28, 2015
Preferred Stock, Shares Authorized (in shares)     5,000,000     5,000,000       5,000,000 5,000,000        
Preferred Stock, Par or Stated Value Per Share (in dollars per share)     $ 0.001     $ 0.001       $ 0.001 $ 0.001        
Common Stock, Shares Authorized (in shares)     50,000,000     50,000,000       50,000,000 50,000,000        
Common Stock, Par or Stated Value Per Share (in dollars per share)     $ 0.001     $ 0.001       $ 0.001 $ 0.001        
Common Stock, Dividends, Per Share, Declared (in dollars per share)           $ 0.20 $ 0.20 $ 0.20 $ 0.20 $ 0.80 $ 0.64        
Dividends, Common Stock, Total                   $ 9,100,000          
Stock Repurchase Program, Authorized Amount                           $ 70,000,000.0 $ 15,000,000.0
Treasury Stock, Shares, Acquired (in shares)     97,785 612,729 383,127                    
Treasury Stock, Value, Acquired, Cost Method     $ 552,000 $ 6,700,000 $ 2,900,000           $ 10,117,000        
Stock Repurchase Program, Remaining Authorized Repurchase Amount           $ 21,900,000       $ 21,900,000          
Common Stock, Dividends, Per Share, Cash Paid (in dollars per share)           $ 0.20 $ 0.20 $ 0.20 $ 0.20   $ 0.64        
Equity Incentive Plan 2016 [Member]                              
Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Authorized (in shares)           2,500,000       2,500,000          
Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Available for Grant (in shares)           1,219,583       1,219,583          
Equity Incentive Plan 2016 [Member] | Restricted Stock [Member]                              
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period (in shares) 1,117,485 22,603                 1,140,088        
Stock Issued During Period, Value, Restricted Stock Award, Gross $ 7,900,000 $ 377,000                          
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period (Year) 3 years 3 years                          
Director [Member]                              
Common Stock, Percentage of Beneficial Stock Outstanding                       5.00% 5.00%    
Broady Trust [Member]                              
Stock Repurchase Program, Authorized Amount                         $ 8,000,000.0    
Open Market Purchases [Member]                              
Stock Repurchase Program, Authorized Amount       $ 4,700,000