Note 9 - Securities Sold Under Agreements to Repurchase (Detail) - Summary Data for Non-Callable Fixed Rate Securities Sold Under Agreements To Repurchase (USD $) In Thousands, unless otherwise specified	Sep. 30, 2012	Dec. 31, 2011
Amount (in Dollars)	$ 1,350,000	$ 1,400,000
Maturing in Three to Five Years [Member] | Non-Callable [Member]
Number of Agreements	2
Amount (in Dollars)	100,000
Weighted Average Interest Rate	2.71%
Maturing in More Than Five Years [Member] | Non-Callable [Member]
Number of Agreements	2
Amount (in Dollars)	100,000
Weighted Average Interest Rate	2.86%
Non-Callable [Member]
Number of Agreements	4
Amount (in Dollars)	$ 200,000
Weighted Average Interest Rate	2.79%