Note 14 - Federal and State Income Taxes - Federal and State Income Tax Expense (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Federal and State Income Taxes
Current									$ 27,237	$ 8,255	$ 2,723
Deferred									(14,530)	6,364	6,292
Federal and state income tax expense	$ 4,009	$ 4,016	$ 2,798	$ 1,884	$ 6,560	$ 3,573	$ 3,073	$ 1,413	$ 12,707	$ 14,619	$ 9,015