Note 8 - Loans - Troubled Debt Restructuring Activity (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Charge-offs	$ 0	$ 0	$ 0	$ 0
Accruing Troubled Debt Restructuring [Member]
Beginning balance	64,898	84,487	65,071	68,566
New restructurings	240	2,589	15,432	25,036
Restructured loans restored to accrual status	0	577	0	2,895
Charge-offs	(1,341)	0	(1,341)	0
Payments	(22,150)	(13,055)	(36,219)	(19,801)
Restructured loans placed on non-accrual status	0	0	(1,296)	(2,098)
Ending balance	41,647	74,598	41,647	74,598
Non-accruing Troubled Debt Restructuring [Member]
Beginning balance	22,457	30,347	24,189	33,415
New restructurings	7,345	2,784	10,505	3,015
Restructured loans restored to accrual status	0	(577)	0	(2,895)
Charge-offs	(2,389)	0	(3,607)	(161)
Payments	(7,626)	(4,836)	(12,596)	(7,754)
Restructured loans placed on non-accrual status	0	0	1,296	2,098
Ending balance	$ 19,787	$ 27,718	$ 19,787	$ 27,718