Note 7 - Income Taxes (Details Textual) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019	Dec. 31, 2020
Effective Income Tax Rate Reconciliation, Percent, Total	0.00%	1.10%	3.00%	1.80%
Deferred Income Tax Expense (Benefit), Total	$ 0	$ 1,070	$ 1,390	$ 2,550
Current Income Tax Expense (Benefit), Total	$ 0	$ 20	$ 40	$ 50
Forecast [Member]
Effective Income Tax Rate Reconciliation, Percent, Total					2.20%