Annual report pursuant to Section 13 and 15(d)

Note 8 - Stock-based Incentive Plans (Details Textual)

v3.22.1
Note 8 - Stock-based Incentive Plans (Details Textual) - USD ($)
1 Months Ended 12 Months Ended
Feb. 29, 2020
Dec. 31, 2021
Dec. 31, 2020
May 31, 2021
Jul. 31, 2020
Oct. 31, 2018
Jul. 31, 2017
May 31, 2016
Oct. 31, 2014
Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Weighted Average Grant Date Fair Value (in dollars per share)   $ 3.40 $ 2.23            
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercises in Period, Intrinsic Value   $ 121,000 $ 0            
Share-based Compensation Arrangement by Share-based Payment Award, Options, Vested in Period, Fair Value   720,000 620,000            
Share-based Payment Arrangement, Nonvested Award, Option, Cost Not yet Recognized, Amount   $ 3,749,000              
Share-based Compensation Arrangement by Share-based Payment Award, Options, Forfeitures in Period (in shares) 540,000 168,000              
Share-based Compensation Arrangements by Share-based Payment Award, Options, Forfeitures in Period, Weighted Average Exercise Price (in dollars per share) $ 10.16 $ 5.63              
Share-based Compensation Arrangement by Share-based Payment Award, Options, Nonvested Options Forfeited, Weighted Average Grant Date Fair Value (in dollars per share) $ 8.33                
Share-based Payment Arrangement, Plan Modification, Incremental Cost $ 0                
Share-based Compensation Arrangement by Share-based Payment Award, Shares Reserved for Future Issuance (in shares) 297,000                
Share-based Payment Arrangement, Expense   $ 2,381,000 $ 2,004,000            
Stock Award Sales Program [Member]                  
Share-based Compensation Arrangement by Share-based Payment Award, Purchase Price of Common Stock, Percent   100.00%              
Common Stock, Capital Shares Reserved for Future Issuance (in shares)       5,000,000 2,583,334 1,833,334 1,500,000 1,000,000 583,334
Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Available for Grant (in shares)   1,840,995              
Share-based Payment Arrangement, Option [Member]                  
Share-based Compensation Arrangement by Share-based Payment Award, Expiration Period (Year)   10 years              
Share-based Payment Arrangement, Nonvested Award, Cost Not yet Recognized, Period for Recognition (Year)   3 years              
Share-based Payment Arrangement, Option [Member] | Minimum [Member]                  
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period (Year)   2 years              
Share-based Payment Arrangement, Option [Member] | Maximum [Member]                  
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period (Year)   4 years              
Non-statutory Options [Member] | Discretionary Option Grant Program [Member]                  
Share-based Compensation Arrangement by Share-based Payment Award, Purchase Price of Common Stock, Percent   85.00%              
Incentive Stock Options [Member] | Discretionary Option Grant Program [Member] | Eligible Employees Owns Equal or Less Than 10% of Voting Stock [Member]                  
Share-based Compensation Arrangement by Share-based Payment Award, Purchase Price of Common Stock, Percent   100.00%              
Incentive Stock Options [Member] | Discretionary Option Grant Program [Member] | Eligible Employee Owns More Than 10% of Voting Stock [Member]                  
Share-based Compensation Arrangement by Share-based Payment Award, Purchase Price of Common Stock, Percent   110.00%              
Restricted Stock Units (RSUs) [Member]                  
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period (Year) 2 years                
Share-based Payment Arrangement, Nonvested Award, Cost Not yet Recognized, Period for Recognition (Year)   1 year 9 months 18 days              
Share-based Compensation Arrangement by Share-based Payment Award, Non-Option Equity Instruments, Granted (in shares) 243,000                
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period, Weighted Average Grant Date Fair Value (in dollars per share) $ 2.60 $ 4.81              
Share-based Payment Arrangement, Nonvested Award, Excluding Option, Cost Not yet Recognized, Amount   $ 864,000              
Stock Warrants [Member]                  
Share-based Compensation Arrangement by Share-based Payment Award, Non-Option Equity Instruments, Granted (in shares)   0 0            
Share-based Payment Arrangement, Nonvested Award, Excluding Option, Cost Not yet Recognized, Amount   $ 0              
Share-based Payment Arrangement, Expense   0 $ 282,000            
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Aggregate Intrinsic Value, Vested   $ 0 $ 206,000