Note 8 - Loans - Troubled Debt Restructuring Activity (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Charge-offs		$ (305)		$ (305)
Accruing Troubled Debt Restructuring [Member]
Beginning balance	84,487	79,819	68,565	65,393
New restructurings	2,589	21,790	25,036	49,973
Restructured loans restored to accrual status	577		2,895
Payments	(13,055)	(35,677)	(19,801)	(41,372)
Restructured loans placed on non-accrual status		(3,574)	(2,098)	(9,396)
Expiration of loan concession upon renewal				(2,240)
Ending balance	74,598	62,358	74,598	62,358
Restructured loans placed on non-accrual status		3,574	2,098	9,396
Non-accruing Troubled Debt Restructuring [Member]
Beginning balance	30,347	30,045	33,416	29,722
New restructurings	2,784	2,360	3,015	2,360
Restructured loans restored to accrual status	(577)		(2,895)
Payments	(4,836)	(1,933)	(7,754)	(5,160)
Restructured loans placed on non-accrual status		(3,574)	(2,098)	(9,396)
Ending balance	27,718	33,691	27,718	33,691
Restructured loans placed on non-accrual status		3,574	2,098	9,396
Charge-offs		(355)	(161)	(1,901)
Foreclosures				$ (726)