Note 10 - Shareholders' Equity (Details Textual) - USD ($) Pure in Thousands	12 Months Ended			19 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2021
Stock Repurchased and Retired During Period, Shares (in shares)	439,000	223,100
Payments for Repurchase of Common Stock	$ 4,408,000	$ 2,666,000
Stock Repurchase Program, Remaining Authorized Repurchase Amount	2,078,000			$ 2,078,000
Share-based Payment Arrangement, Expense	185,000	$ 375,000
Share-based Payment Arrangement, Nonvested Award, Cost Not yet Recognized, Amount, Total	$ 37,000			$ 37,000
Share-based Payment Arrangement, Nonvested Award, Cost Not yet Recognized, Period for Recognition (Year)	5 months 1 day
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Number, Ending Balance (in shares)	427,580	568,740	1,326,414	427,580
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Expected Dividend Rate			0.00%
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercises in Period, Intrinsic Value	$ 806,000	$ 10,772,000
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercises in Period (in shares)	134,494	757,674
Proceeds from Stock Options Exercised	$ 427,000
The2004 Plan Member
Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Available for Grant (in shares)	5,000,000			5,000,000
Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Gross (in shares)		5,009,750
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period (Year)	3 years
Share-based Compensation Arrangement by Share-based Payment Award, Expiration Period (Year)	5 years
Incentive Plan 2020 [Member]
Common Stock, Capital Shares Reserved for Future Issuance (in shares)	1,800,000			1,800,000
Incentive Plan 2020 [Member] | Restricted Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period (Year)	2021 years
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period (in shares)	15,140	8,912		24,052
Share-based Payment Arrangement, Expense	$ 131,000	$ 6,000
Share-based Payment Arrangement, Nonvested Award, Cost Not yet Recognized, Amount, Total	$ 79,000			$ 79,000
Share-based Payment Arrangement, Nonvested Award, Cost Not yet Recognized, Period for Recognition (Year)	8 months 23 days