Note 8 - Loans - Troubled Debt Restructuring Activity (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017
Charge-offs	$ (305)		$ (305)
Accruing Troubled Debt Restructuring [Member]
Beginning balance	79,819	74,708	65,393	81,680	$ 86,555
New restructurings	21,790	18,347	49,973	20,412
Restructured loans restored to accrual status				10,303
Payments	(35,677)	(6,500)	(41,372)	(9,816)
Restructured loans placed on non-accrual status	(3,574)		(9,396)	(1,138)
Expiration of loan concession upon renewal			(2,240)	(14,886)
Ending balance	62,358	86,555	62,358	86,555	62,358
Non-accruing Troubled Debt Restructuring [Member]
Beginning balance	30,045	25,442	29,722	39,923	20,870
New restructurings	2,360	649	2,360	3,794
Restructured loans restored to accrual status	3,574		9,396	1,138
Payments	(1,933)	(1,814)	(5,160)	(9,330)
Restructured loans placed on non-accrual status				(10,303)
Charge-offs	(355)	(3,407)	(1,901)	(4,352)
Foreclosures			(726)
Ending balance	$ 33,691	$ 20,870	$ 33,691	$ 20,870	$ 33,691