Note 6 - Investment Securities (Detail) (USD $)	3 Months Ended		12 Months Ended
	Mar. 31, 2012	Mar. 31, 2011	Dec. 31, 2011
Proceeds from Sale of Mortgage Backed Securities (MBS) categorized as Available-for-sale	$ 117,600,000	$ 315,300,000
Proceeds from Maturities, Prepayments and Calls of Mortgage Backed Securities (MBS)	94,200,000	41,600,000
Proceeds From Sales and Repayments of Other Investment Securities	30,600,000	217,300,000
Proceeds from Maturities, Repayments and Calls of Trading Securities Held-for-investment	200,000,000	27,000,000,000
Trading Securities, Realized Gain	2,800,000	6,200,000
Trading Securities, Realized Loss	595,000	0
Available-for-sale, Securities in Unrealized Loss Positions, Qualitative Disclosure, Other, Percentage of Nonperforming Assets	25.10%
Percentage of Unrealized Losses for Securities with Unrealized Losses for Less Than Twelve Months	2.10%
Percentage of Unrealized Losses for Securities with Unrealized Losses for Greater than Twelve Months	8.10%
Pledged Investment Securities	$ 1,520,000,000		$ 1,680,000,000