Note 8 - Loans - Troubled Debt Restructuring Activity (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Charge-offs
Accruing Troubled Debt Restructuring [Member]
Beginning balance	65,071	68,566
New restructurings	1,948	17,320
Restructured loans restored to accrual status		2,318
Payments	(4,071)	(3,891)
Restructured loans placed on non-accrual status		(1,528)
Ending balance	62,948	82,785
Non-accruing Troubled Debt Restructuring [Member]
Beginning balance	24,189	33,415
New restructurings		231
Restructured loans restored to accrual status		(2,318)
Payments	(481)	(1,661)
Restructured loans placed on non-accrual status		1,528
Ending balance	23,301	31,195
Charge-offs	$ (407)