Note 6 - Investment Securities (Details) (USD $)	3 Months Ended	9 Months Ended
	Mar. 31, 2013	Sep. 30, 2013	Sep. 30, 2012	Dec. 31, 2012
Note 6 - Investment Securities (Details) [Line Items]
Investment Securities		$ 1,700,000,000		$ 2,100,000,000
Held-to-maturity Securities, Transferred Security, at Carrying Value		722,500,000
Held-to-maturity Securities, Transferred Security, Unrealized Gain (Loss)	40,500,000
Proceeds from Sale of Mortgage Backed Securities (MBS) categorized as Available-for-sale		348,700,000	369,000,000
Proceeds from Maturities, Prepayments and Calls of Mortgage Backed Securities (MBS)		237,900,000	280,700,000
Proceeds From Sales and Repayments of Other Investment Securities		555,200,000	61,000,000
Proceeds From Maturities Repayments And Calls Of Held For Investment		180,100,000	494,200,000
Realized Gain From Sale and Call of Investment Securities		27,200,000	13,800,000
Realized Loss From Sale and Call of Investment Securities			607,000
Temporarily Impaired Securities As Percentage of Investment Securities		58.60%
Percentage of Unrealized Losses for Securities with Unrealized Losses for Less Than Twelve Months		4.90%
Percentage of Unrealized Losses for Securities with Unrealized Losses for Greater than Twelve Months		5.60%
Pledged Investment Securities		$ 941,800,000		$ 1,450,000,000
Corporate Bonds Issued By Financial Institutions [Member]
Note 6 - Investment Securities (Details) [Line Items]
Available-for-sale, Securities in Unrealized Loss Positions, Qualitative Disclosure, Number of Positions		14