Note 8 - Loans - Troubled Debt Restructuring Activity (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Charge-offs	$ 0	$ 0	$ 0	$ 0
Accruing Troubled Debt Restructuring [Member]
Beginning balance	31,671	64,898	35,336	65,071
New restructurings	2,983	240	5,417	15,432
Restructured loans restored to accrual status	263	0	263	0
Charge-offs	0	(1,341)	0	(1,341)
Payments	(6,330)	(22,150)	(12,429)	(36,219)
Restructured loans placed on non-accrual status	0	0	0	(1,296)
New restructurings	2,983	240	5,417	15,432
Ending balance	28,587	41,647	28,587	41,647
Non-accruing Troubled Debt Restructuring [Member]
Beginning balance	12,670	22,457	18,048	24,189
New restructurings	0	7,345	0	10,505
Restructured loans restored to accrual status	(263)	0	(263)	0
Charge-offs	0	(2,389)	(4,970)	(3,607)
Payments	(2,488)	(7,626)	(2,896)	(12,596)
Restructured loans placed on non-accrual status	0	0	0	1,296
New restructurings	0	7,345	0	10,505
Ending balance	$ 9,919	$ 19,787	$ 9,919	$ 19,787