Note 8 - Loans - Average Balance and Interest Income Recognized Related to Impaired Loans (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Impaired Loans Average Recorded Investment	$ 133,809	$ 137,595	$ 129,741	$ 127,958
Impaired Loans Interest Income Recognized	1,224	994	2,275	1,976
Commercial Portfolio Segment [Member]
Impaired Loans Average Recorded Investment	46,763	19,376	45,978	21,345
Impaired Loans Interest Income Recognized	498	86	825	171
Real Estate Construction Portfolio Segment [Member]
Impaired Loans Average Recorded Investment	8,378	42,752	8,258	29,912
Impaired Loans Interest Income Recognized		356		696
Commercial Real Estate Portfolio Segment [Member]
Impaired Loans Average Recorded Investment	64,004	60,295	61,316	60,847
Impaired Loans Interest Income Recognized	633	445	1,264	898
Residential Mortgage and Equity Lines Portfolio Segment [Member]
Impaired Loans Average Recorded Investment	14,664	15,172	14,189	15,854
Impaired Loans Interest Income Recognized	$ 93	$ 107	$ 186	$ 211