Note 7 - Loans - Allowance for Loan Losses by Portfolio Segment (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Net (charge-offs)/recoveries	$ 265	$ (6,454)	$ (657)	$ (364)
June 30, 2017 Ending Balance	115,809	122,948	115,809	122,948
Reserve for impaired loans		7,724		7,724
Reserve for non-impaired loans	115,809	115,224	115,809	115,224
Reserve for off-balance sheet credit commitments	4,513	2,124	4,513	2,124
March 31, 2017 Ending Balance	115,544	134,552	118,966	138,963
Provision/(credit) for possible credit losses		(5,150)	(2,500)	(15,651)
Charge-offs	(527)	(7,633)	(2,285)	(9,961)
Recoveries	792	1,179	1,628	9,597
Commercial Portfolio Segment [Member]
Net (charge-offs)/recoveries	(192)	(5,961)	(904)	(7,044)
June 30, 2017 Ending Balance	46,744	50,590	46,744	50,590
Reserve for impaired loans		1,395		1,395
Reserve for non-impaired loans	46,743	49,195	46,743	49,195
Reserve for off-balance sheet credit commitments	2,583	1,969	2,583	1,969
March 31, 2017 Ending Balance	47,276	56,381	49,203	56,199
Provision/(credit) for possible credit losses	(340)	170	(1,556)	1,435
Charge-offs	(527)	(6,688)	(1,730)	(8,758)
Recoveries	335	727	826	1,714
Real Estate Construction Portfolio Segment [Member]
Net (charge-offs)/recoveries	47	47	96	7,323
June 30, 2017 Ending Balance	17,844	10,753	17,844	10,753
Reserve for impaired loans
Reserve for non-impaired loans	17,844	10,753	17,844	10,753
Reserve for off-balance sheet credit commitments	1,707		1,707
March 31, 2017 Ending Balance	19,768	12,744	23,268	22,170
Provision/(credit) for possible credit losses	(1,971)	(2,038)	(5,520)	(18,740)
Charge-offs
Recoveries	47	47	96	7,323
Commercial Real Estate Portfolio Segment [Member]
Net (charge-offs)/recoveries	403	(546)	136	(513)
June 30, 2017 Ending Balance	36,840	46,090	36,840	46,090
Reserve for impaired loans		5,891		5,891
Reserve for non-impaired loans	36,840	40,199	36,840	40,199
Reserve for off-balance sheet credit commitments	74	34	74	34
March 31, 2017 Ending Balance	35,960	50,451	34,864	49,440
Provision/(credit) for possible credit losses	477	(3,815)	1,840	(2,837)
Charge-offs		(945)	(555)	(1,055)
Recoveries	403	399	691	542
Residential Mortgage and Equity Lines Portfolio Segment [Member]
Net (charge-offs)/recoveries	7	6	15	(130)
June 30, 2017 Ending Balance	14,364	15,503	14,364	15,503
Reserve for impaired loans		438		438
Reserve for non-impaired loans	14,364	15,065	14,364	15,065
Reserve for off-balance sheet credit commitments	143	119	143	119
March 31, 2017 Ending Balance	12,526	14,969	11,620	11,145
Provision/(credit) for possible credit losses	1,831	528	2,729	4,488
Charge-offs				(148)
Recoveries	7	6	15	18
Installment and Other Loans [Member ]
Net (charge-offs)/recoveries
June 30, 2017 Ending Balance	17	12	17	12
Reserve for impaired loans
Reserve for non-impaired loans	18	12	18	12
Reserve for off-balance sheet credit commitments	6	2	6	2
March 31, 2017 Ending Balance	14	7	11	9
Provision/(credit) for possible credit losses	3	5	7	3
Charge-offs
Recoveries