Note 6 - Income Taxes (Details Textual) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended		12 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020	Dec. 31, 2021
Effective Income Tax Rate Reconciliation, Percent, Total	0.00%	4.80%	0.10%	4.40%
Deferred Income Tax Expense (Benefit), Total	$ 0	$ 700	$ 0	$ 1,400
Current Income Tax Expense (Benefit), Total	0	$ 10	(40)	$ 30
Unrecognized Tax Benefits that Would Impact Effective Tax Rate	$ 0		$ 0
Forecast [Member]
Effective Income Tax Rate Reconciliation, Percent, Total					(0.10%)