Note 5 - Loans (Details) - Activity in the Allowance for Credit Losses - 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
Allowance for Loan Losses
Balance, beginning				$ 161,420				$ 161,420	$ 173,889
(Reversal)/provision for possible loan losses	$ (3,000)	$ (1,250)	$ (2,150)	(5,000)	$ (2,000)	$ (5,100)	$ (3,700)	(11,400)	(11,172)	$ (3,000)
Transfers to reserve for off-balance sheet credit commitments									(372)
Loans charged off								(20,427)	(22,235)	(20,442)
Recoveries of charged off loans								9,370	20,938	14,009
Balance, ending	138,963				161,420			138,963	161,420	173,889
Beginning of Period [Member]
Allowance for Loan Losses
Balance, beginning				161,420				161,420	173,889	183,322
Balance, ending					161,420				161,420	173,889
End of Period [Member]
Allowance for Loan Losses
Balance, beginning				161,420				161,420	173,889
Balance, ending	138,963				161,420			138,963	161,420	173,889
Reserve for Off-Balance Sheet Credit Commitments [Member]
Allowance for Loan Losses
(Reversal)/provision for possible loan losses								(455)	586
Reserve for Off-Balance Sheet Credit Commitments [Member] | Beginning of Period [Member]
Allowance for Loan Losses
Balance, beginning				1,949				1,949	1,363	1,363
Balance, ending					1,949				1,949	1,363
Reserve for Off-Balance Sheet Credit Commitments [Member] | End of Period [Member]
Allowance for Loan Losses
Balance, beginning				$ 1,949				1,949	1,363
Balance, ending	$ 1,494				$ 1,949			$ 1,494	$ 1,949	$ 1,363