Note 5 - Loans - Activity in the Allowance for Credit Losses (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
Reversal for credit losses			$ (5,150)	(10,500)	$ (3,000)	$ (1,250)	$ (2,150)	(5,000)	(15,650)	(11,400)	(10,800)
Transfers to reserve for off-balance sheet credit commitments											(372)
Loans charged off									(18,903)	(20,427)	(22,235)
Recoveries of charged off loans									14,556	9,370	20,938
Balance at end of year	118,966				138,963				118,966	138,963	161,420
Reserve for Off-balance Sheet Credit Commitments
Balance at beginning of year				138,963				161,420	138,963	161,420	173,889
Provision/(reversal) for credit losses and transfers			$ (5,150)	(10,500)	(3,000)	$ (1,250)	$ (2,150)	(5,000)	(15,650)	(11,400)	(10,800)
Balance at end of year	118,966				138,963				118,966	138,963	161,420
Reserve for off Balance Sheet Credit Commitments [Member]
Balance at beginning of year				1,494				1,949	1,494	1,949	1,363
Reversal for credit losses									1,730	(455)	586
Balance at end of year	3,224				1,494				3,224	1,494	1,949
Reserve for Off-balance Sheet Credit Commitments
Balance at beginning of year				$ 1,494				$ 1,949	1,494	1,949	1,363
Provision/(reversal) for credit losses and transfers									1,730	(455)	586
Balance at end of year	$ 3,224				$ 1,494				$ 3,224	$ 1,494	$ 1,949