Note 4 - Loans - Troubled Debt Restructuring Activity (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Charge-offs	$ 0	$ (4,063)	$ 0
Accruing Troubled Debt Restructuring [Member]
Beginning balance	35,336	65,071	68,565
New restructurings	5,417	15,432	26,114
Restructured loans restored to accrual status	263	365	2,896
Charge-offs	0	(1,341)	0
Payments	(13,295)	(42,895)	(30,406)
Restructured loans placed on non-accrual	0	(1,296)	(2,098)
New restructurings	5,417	15,432	26,114
Ending balance	27,721	35,336	65,071
Non-accruing Troubled Debt Restructuring [Member]
Beginning balance	18,048	24,189	33,416
New restructurings	0	10,547	3,015
Restructured loans restored to accrual status	(263)	(365)	(2,896)
Charge-offs	(4,970)	(3,607)	(2,347)
Payments	(3,830)	(14,012)	(9,097)
Restructured loans placed on non-accrual	0	1,296	2,098
New restructurings	0	10,547	3,015
Ending balance	$ 8,985	$ 18,048	$ 24,189