Note 8 - Loans - Troubled Debt Restructuring Activity (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Accruing Troubled Debt Restructuring [Member]
Beginning balance	$ 82,785	$ 80,419	$ 68,565	$ 65,393
New restructurings	5,127	500	22,447	28,183
Restructured loans restored to accrual status			2,318
Payments	(2,855)	(1,100)	(6,746)	(5,695)
Restructured loans placed on non-accrual status	(570)		(2,098)	(5,822)
Expiration of loan concession upon renewal				(2,240)
Ending balance	84,487	79,819	84,487	79,819
Restructured loans placed on non-accrual status	570		2,098	5,822
Non-accruing Troubled Debt Restructuring [Member]
Beginning balance	31,195	32,779	33,416	29,722
New restructurings			231
Restructured loans restored to accrual status			(2,318)
Payments	(1,257)	(2,237)	(2,918)	(3,227)
Restructured loans placed on non-accrual status	(570)		(2,098)	(5,822)
Ending balance	30,347	30,045	30,347	30,045
Restructured loans placed on non-accrual status	570		2,098	5,822
Charge-offs	(161)	(497)	(161)	(1,546)
Foreclosures				$ (726)