Note 5 - Loans - Allowance for Loan Losses by Portfolio Segment (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Balance at beginning of year				$ 138,963				$ 161,420	$ 138,963	$ 161,420	$ 173,889
Provision/(reversal) for loan losses			$ (5,150)	(10,500)	$ (3,000)	$ (1,250)	$ (2,150)	(5,000)	(15,650)	(11,400)	(10,800)
Charge-offs									(18,903)	(20,427)	(22,235)
Recoveries									14,556	9,370	20,938
Net (Charge-offs)/Recoveries									(4,347)	(11,057)
Balance at end of year	118,966				138,963				118,966	138,963	161,420
Reserve for impaired loans	2,796				7,749				2,796	7,749
Reserve for non-impaired loans	116,170				131,214				116,170	131,214
Reserve for off-balance sheet credit commitments	3,224				1,494				3,224	1,494
Commercial Portfolio Segment [Member]
Balance at beginning of year				56,199				47,501	56,199	47,501
Provision/(reversal) for loan losses									1,815	20,505
Charge-offs									(12,955)	(16,426)
Recoveries									4,144	4,619
Net (Charge-offs)/Recoveries									(8,811)	(11,807)
Balance at end of year	49,203				56,199				49,203	56,199	47,501
Reserve for impaired loans	1,827				530				1,827	530
Reserve for non-impaired loans	47,376				55,669				47,376	55,669
Reserve for off-balance sheet credit commitments	2,091				810				2,091	810
Real Estate Construction Portfolio Segment [Member]
Balance at beginning of year				22,170				27,652	22,170	27,652
Provision/(reversal) for loan losses									(6,819)	(5,684)
Charge-offs
Recoveries									7,917	202
Net (Charge-offs)/Recoveries									7,917	202
Balance at end of year	23,268				22,170				23,268	22,170	27,652
Reserve for impaired loans
Reserve for non-impaired loans	23,268				22,170				23,268	22,170
Reserve for off-balance sheet credit commitments	940				526				940	526
Commercial Real Estate Portfolio Segment [Member]
Balance at beginning of year				49,440				74,673	49,440	74,673
Provision/(reversal) for loan losses									(11,123)	(26,035)
Charge-offs									(5,948)	(3,716)
Recoveries									2,495	4,518
Net (Charge-offs)/Recoveries									(3,453)	802
Balance at end of year	34,864				49,440				34,864	49,440	74,673
Reserve for impaired loans	573				6,792				573	6,792
Reserve for non-impaired loans	34,291				42,648				34,291	42,648
Reserve for off-balance sheet credit commitments	41				158				41	158
Residential Mortgage and Equity Lines Portfolio Segment [Member]
Balance at beginning of year				11,145				11,578	11,145	11,578
Provision/(reversal) for loan losses									475	(179)
Charge-offs										(285)
Recoveries										31
Net (Charge-offs)/Recoveries										(254)
Balance at end of year	11,620				11,145				11,620	11,145	11,578
Reserve for impaired loans	396				427				396	427
Reserve for non-impaired loans	11,224				10,718				11,224	10,718
Reserve for off-balance sheet credit commitments	146								146
Consumer Portfolio Segment [Member]
Balance at beginning of year				$ 9				$ 16	9	16
Provision/(reversal) for loan losses									2	(7)
Charge-offs
Recoveries
Net (Charge-offs)/Recoveries
Balance at end of year	11				9				11	9	$ 16
Reserve for impaired loans
Reserve for non-impaired loans	11				9				11	9
Reserve for off-balance sheet credit commitments	$ 6								$ 6