Note 5 - Loans - Troubled Debt Restructuring Activity (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Charge-offs		$ (305)	$ (830)
Accruing Troubled Debt Restructuring [Member]
Beginning balance	68,565	65,393	81,680
New restructurings	26,114	73,426	26,965
Restructured loans restored to accrual status	2,896		10,303
Charge-offs			(88)
Payments	(30,406)	(54,095)	(24,192)
Restructured loans placed on non-accrual	(2,098)	(13,919)	(13,984)
Expiration of loan concession		(2,240)	(15,291)
Ending balance	65,071	68,565	65,393
Non-accruing Troubled Debt Restructuring [Member]
Beginning balance	33,416	29,722	39,923
New restructurings	3,015	4,009	6,940
Restructured loans restored to accrual status	(2,896)		(10,303)
Charge-offs	(2,347)	(1,650)	(5,271)
Payments	(9,097)	(11,341)	(15,551)
Restructured loans placed on non-accrual	2,098	13,919	13,984
Foreclosures		(1,243)
Ending balance	$ 24,189	$ 33,416	$ 29,722