Note 9 - 401(k) Retirement Plan (Details Textual) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020
Defined Contribution Plan, Eligibility Service Period (Month)	3 months
Defined Contribution Plan, Eligibility Age of Employee (Year)	18 years
Defined Contribution Plan, Maximum Annual Contributions Per Employee, Percent	60.00%
Defined Contribution Plan, Employer Matching Contribution Rate	25.00%
Defined Contribution Plan, Employer Matching Contribution, Percent of Employees' Gross Pay	6.00%
Defined Contribution Plan, Cost	$ 276	$ 267