Note 5 - Loans (Details) - Allowance for Loan Losses by Portfolio Segment - USD ($) $ in Thousands	3 Months Ended							12 Months Ended
	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Financing Receivable, Allowance for Credit Losses [Line Items]
Balance, beginning				$ 161,420				$ 161,420	$ 173,889
Provision/(reversal) for possible loan losses	$ (3,000)	$ (1,250)	$ (2,150)	(5,000)	$ (2,000)	$ (5,100)	$ (3,700)	(11,400)	(11,172)	$ (3,000)
Charge-offs								(20,427)	(22,235)	(20,442)
Recoveries								9,370	20,938	14,009
Net charge-offs								(11,057)	(1,297)
Balance, ending	138,963				161,420			138,963	161,420	173,889
Reserve to impaired loans	7,749				11,798			7,749	11,798
Reserve to non-impaired loans	131,214				149,622			131,214	149,622
Reserve for off-balance sheet credit commitments	1,494				1,949			1,494	1,949
Commercial Portfolio Segment [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Balance, beginning				47,501				47,501	65,103
Provision/(reversal) for possible loan losses								20,505	(22,244)
Charge-offs								(16,426)	(7,875)
Recoveries								4,619	12,517
Net charge-offs								(11,807)	4,642
Balance, ending	56,199				47,501			56,199	47,501	65,103
Reserve to impaired loans	530				1,263			530	1,263
Reserve to non-impaired loans	55,669				46,238			55,669	46,238
Reserve for off-balance sheet credit commitments	810				923			810	923
Real Estate Construction Portfolio Segment [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Balance, beginning				27,652				27,652	11,999
Provision/(reversal) for possible loan losses								(5,684)	19,853
Charge-offs									(6,747)
Recoveries								202	2,547
Net charge-offs								202	(4,200)
Balance, ending	22,170				27,652			22,170	27,652	11,999
Reserve to impaired loans					1,077				1,077
Reserve to non-impaired loans	22,170				26,575			22,170	26,575
Reserve for off-balance sheet credit commitments	526				728			526	728
Commercial Real Estate Portfolio Segment [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Balance, beginning				74,673				74,673	84,753
Provision/(reversal) for possible loan losses								(26,035)	(8,197)
Charge-offs								(3,716)	(7,458)
Recoveries								4,518	5,575
Net charge-offs								802	(1,883)
Balance, ending	49,440				74,673			49,440	74,673	84,753
Reserve to impaired loans	6,792				8,993			6,792	8,993
Reserve to non-impaired loans	42,648				65,680			42,648	65,680
Reserve for off-balance sheet credit commitments	158				259			158	259
Residential Mortgage and Equity Lines Portfolio Segment [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Balance, beginning				11,578				11,578	12,005
Provision/(reversal) for possible loan losses								(179)	(558)
Charge-offs								(285)	(155)
Recoveries								31	286
Net charge-offs								(254)	131
Balance, ending	11,145				11,578			11,145	11,578	12,005
Reserve to impaired loans	427				465			427	465
Reserve to non-impaired loans	10,718				11,113			10,718	11,113
Reserve for off-balance sheet credit commitments					39				39
Consumer Portfolio Segment [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Balance, beginning				$ 16				16	29
Provision/(reversal) for possible loan losses								(7)	(26)
Recoveries									13
Net charge-offs									13
Balance, ending	9				16			9	16	$ 29
Reserve to impaired loans					0				0
Reserve to non-impaired loans	$ 9				$ 16			$ 9	$ 16