Note 4 - Income Taxes (Details Textual) - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020	Dec. 31, 2020
Effective Income Tax Rate Reconciliation, Percent, Total	23.50%	17.90%	23.00%	8.10%
Effective Income Tax Rate Change, Share-based Compensation	$ 653,000		$ 4,700,000
Change in Tax Law, Deferral of Social Security Tax Payments					$ 1,313,000
Social Security Tax Payable, Current	$ 656,000		$ 656,000