Note 6 - Investment Securities (Detail) (USD $)	9 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Dec. 31, 2011
Proceeds from Sale of Mortgage Backed Securities (MBS) categorized as Available-for-sale	$ 368,972,000	$ 759,654,000
Proceeds from Maturities, Prepayments and Calls of Mortgage Backed Securities (MBS)	280,700,000	166,300,000
Proceeds From Sales and Repayments of Other Investment Securities	61,000,000	503,600,000
Proceeds from Maturities, Repayments and Calls of Trading Securities Held-for-investment	494,200,000	385,000,000
Trading Securities, Realized Gain	13,800,000	20,200,000
Trading Securities, Realized Loss	607,000	0
Available-for-sale, Securities in Unrealized Loss Positions, Qualitative Disclosure, Other, Percentage of Nonperforming Assets	17.70%
Percentage of Unrealized Losses for Securities with Unrealized Losses for Less Than Twelve Months	2.20%
Percentage of Unrealized Losses for Securities with Unrealized Losses for Greater than Twelve Months	6.20%
Pledged Investment Securities	$ 1,570,000,000		$ 1,680,000,000