Note 8 - Loans - Allowance for Loan Losses by Portfolio Segment (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Beginning Balance	$ 122,391	$ 123,279
Provision/(reversal) for possible credit losses		(3,000)
Charge-offs	(1,231)	(19)
Recoveries	1,395	1,824
Net (charge-offs)/recoveries	164	1,805
Ending Balance	122,555	122,084
Reserve for impaired loans	1,414	1,502
Reserve for non-impaired loans	121,141	120,582
Reserve for off-balance sheet credit commitments	3,850	4,588
Commercial Portfolio Segment [Member]
Beginning Balance	54,978	49,796
Provision/(reversal) for possible credit losses	962	3,907
Charge-offs	(1,231)	(19)
Recoveries	41	913
Net (charge-offs)/recoveries	(1,190)	894
Ending Balance	54,750	54,597
Reserve for impaired loans	498	11
Reserve for non-impaired loans	54,252	54,586
Reserve for off-balance sheet credit commitments	1,759	2,747
Real Estate Construction Portfolio Segment [Member]
Beginning Balance	19,626	24,838
Provision/(reversal) for possible credit losses	53	(3,018)
Charge-offs
Recoveries	1,044	44
Net (charge-offs)/recoveries	1,044	44
Ending Balance	20,723	21,864
Reserve for impaired loans
Reserve for non-impaired loans	20,723	21,864
Reserve for off-balance sheet credit commitments	1,668	1,515
Commercial Real Estate Portfolio Segment [Member]
Beginning Balance	33,487	37,610
Provision/(reversal) for possible credit losses	(566)	(4,163)
Charge-offs
Recoveries	152	783
Net (charge-offs)/recoveries	152	783
Ending Balance	33,073	34,230
Reserve for impaired loans	667	1,145
Reserve for non-impaired loans	32,406	33,085
Reserve for off-balance sheet credit commitments	146	138
Residential Mortgage and Equity Lines Portfolio Segment [Member]
Beginning Balance	14,282	11,013
Provision/(reversal) for possible credit losses	(465)	275
Charge-offs
Recoveries	158	84
Net (charge-offs)/recoveries	158	84
Ending Balance	13,975	11,372
Reserve for impaired loans	249	346
Reserve for non-impaired loans	13,726	11,026
Reserve for off-balance sheet credit commitments	275	182
Installment and Other Loans [Member ]
Beginning Balance	18	22
Provision/(reversal) for possible credit losses	16	(1)
Charge-offs
Recoveries
Net (charge-offs)/recoveries
Ending Balance	34	21
Reserve for impaired loans
Reserve for non-impaired loans	34	21
Reserve for off-balance sheet credit commitments	$ 2	$ 6