Note 8 - Loans - Average Balance and Interest Income Recognized Related to Impaired Loans (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Impaired Loans Average Recorded Investment	$ 125,627	$ 118,213
Impaired Loans Interest Income Recognized	1,078	1,000
Commercial Portfolio Segment [Member]
Impaired Loans Average Recorded Investment	45,183	23,335
Impaired Loans Interest Income Recognized	334	83
Real Estate Construction Portfolio Segment [Member]
Impaired Loans Average Recorded Investment	8,137	16,930
Impaired Loans Interest Income Recognized		340
Commercial Real Estate Portfolio Segment [Member]
Impaired Loans Average Recorded Investment	58,598	61,405
Impaired Loans Interest Income Recognized	644	445
Residential Mortgage and Equity Lines Portfolio Segment [Member]
Impaired Loans Average Recorded Investment	13,709	16,543
Impaired Loans Interest Income Recognized	$ 100	$ 132