Note 8 - Loans - Troubled Debt Restructuring Activity (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Accruing Troubled Debt Restructuring [Member]
Beginning balance	$ 68,565	$ 65,393
New restructurings	17,320	27,683
Restructured loans restored to accrual status	2,318
Payments	(3,891)	(4,595)
Restructured loans placed on non-accrual status	(1,528)	(5,822)
Expiration of loan concession upon renewal		(2,240)
Restructured loans placed on non-accrual status	1,528	5,822
Ending balance	82,785	80,419
Non-accruing Troubled Debt Restructuring [Member]
Beginning balance	33,416	29,722
New restructurings	231
Restructured loans restored to accrual status	(2,318)
Payments	(1,661)	(990)
Restructured loans placed on non-accrual status	(1,528)	(5,822)
Restructured loans placed on non-accrual status	1,528	5,822
Charge-offs		(1,049)
Foreclosures		(726)
Ending balance	$ 31,195	$ 32,779