Note 1 - Summary of Significant Accounting Policies - Reclassification Adjustment (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Non-interest income	$ 23,810	$ 23,994	$ 23,765
Compensation expense	46,104	42,581	40,814
Technology and communication expense	8,897	7,957	7,040
Accounting Standards Update 2014-09 [Member]
Non-interest income	1,677	1,629	1,563
Compensation expense	46,104	42,581	40,814
Technology and communication expense	8,897	7,957	7,040
Net impact
Previously Reported [Member] | Accounting Standards Update 2014-09 [Member]
Non-interest income	2,224	2,200	2,145
Compensation expense	46,107	42,584	40,817
Technology and communication expense	9,441	8,525	7,619
Restatement Adjustment [Member] | Accounting Standards Update 2014-09 [Member]
Non-interest income	(547)	(571)	(582)
Compensation expense	(3)	(3)	(3)
Technology and communication expense	$ (544)	$ (568)	$ (579)