Note 8 - Loans - Allowance for Loan Losses by Portfolio Segment (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
June 30, 2017 Ending Balance	$ 115,809	$ 122,948	$ 118,966	$ 138,963
Provision/(credit) for possible credit losses			(2,500)	(15,650)
Charge-offs	(385)	(7,903)	(2,670)	(17,865)
Recoveries	6,111	2,897	7,739	12,494
Net (charge-offs)/recoveries	5,726	(5,006)	5,069	(5,371)
September 30, 2017 Ending Balance	121,535	117,942	121,535	117,942
Reserve for impaired loans	2,606	2,943	2,606	2,943
Reserve for non-impaired loans	118,929	114,999	118,929	114,999
Reserve for off-balance sheet credit commitments	4,254	2,229	4,254	2,229
Commercial Portfolio Segment [Member]
June 30, 2017 Ending Balance	46,744	50,590	49,203	56,199
Provision/(credit) for possible credit losses	3,800	4,380	2,245	5,815
Charge-offs	(80)	(3,277)	(1,810)	(12,035)
Recoveries	575	2,006	1,401	3,720
Net (charge-offs)/recoveries	495	(1,271)	(409)	(8,315)
September 30, 2017 Ending Balance	51,039	53,699	51,039	53,699
Reserve for impaired loans	1,461	1,320	1,461	1,320
Reserve for non-impaired loans	49,578	52,379	49,578	52,379
Reserve for off-balance sheet credit commitments	2,760	2,112	2,760	2,112
Real Estate Construction Portfolio Segment [Member]
June 30, 2017 Ending Balance	17,844	10,753	23,268	22,170
Provision/(credit) for possible credit losses	4,117	(2,056)	(1,403)	(20,796)
Charge-offs
Recoveries	47	548	143	7,871
Net (charge-offs)/recoveries	47	548	143	7,871
September 30, 2017 Ending Balance	22,008	9,245	22,008	9,245
Reserve for impaired loans
Reserve for non-impaired loans	22,008	9,245	22,008	9,245
Reserve for off-balance sheet credit commitments	1,206		1,206
Commercial Real Estate Portfolio Segment [Member]
June 30, 2017 Ending Balance	36,840	46,090	34,864	49,440
Provision/(credit) for possible credit losses	(4,615)	3,132	(2,775)	295
Charge-offs	(305)	(4,626)	(860)	(5,681)
Recoveries	5,482	337	6,173	879
Net (charge-offs)/recoveries	5,177	(4,289)	5,313	(4,802)
September 30, 2017 Ending Balance	37,402	44,933	37,402	44,933
Reserve for impaired loans	823	1,248	823	1,248
Reserve for non-impaired loans	36,579	43,685	36,579	43,685
Reserve for off-balance sheet credit commitments	109	35	109	35
Residential Mortgage and Equity Lines Portfolio Segment [Member]
June 30, 2017 Ending Balance	14,364	15,503	11,620	11,145
Provision/(credit) for possible credit losses	(3,309)	(5,452)	(580)	(963)
Charge-offs				(149)
Recoveries	7	6	22	24
Net (charge-offs)/recoveries	7	6	22	(125)
September 30, 2017 Ending Balance	11,062	10,057	11,062	10,057
Reserve for impaired loans	322	375	322	375
Reserve for non-impaired loans	10,740	9,682	10,740	9,682
Reserve for off-balance sheet credit commitments	175	80	175	80
Installment and Other Loans [Member ]
June 30, 2017 Ending Balance	17	12	11	9
Provision/(credit) for possible credit losses	7	(4)	13	(1)
Charge-offs
Recoveries
Net (charge-offs)/recoveries
September 30, 2017 Ending Balance	24	8	24	8
Reserve for impaired loans
Reserve for non-impaired loans	24	8	24	8
Reserve for off-balance sheet credit commitments	$ 4	$ 2	$ 4	$ 2