Note 9 - Securities Sold Under Agreements to Repurchase (Detail) - Callable Securities Sold Under Agreements to Repurchase (Callable [Member], USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2013
No. of agreements	18
Amount (in Dollars)	$ 950,000
Weighted average rate	3.98%
Fixed to Floating One Hundred and Fifty Million With Three Agreements At Three Point Seven Nine Percent [Member]
Maximum rate	3.79%
Minimum rate	0.00%
No. of agreements	3
Amount (in Dollars)	150,000
Weighted average rate	3.78%
Final maturity	2,014
Fixed To Floating Fifty Million With One Agreement At Three Point Five Three Percent Member
Maximum rate	3.53%
Minimum rate	0.00%
No. of agreements	1
Amount (in Dollars)	50,000
Weighted average rate	3.53%
Final maturity	2,014
Fixed to Floating 3.5% With Four Agreements [Member]
Maximum rate	3.50%
Minimum rate	0.00%
No. of agreements	4
Amount (in Dollars)	200,000
Weighted average rate	3.50%
Final maturity	2,014
Fixed To Floating One Hundred And Fifty Million With Three Agreements At Three Point Five Percent Member
Maximum rate	3.50%
Minimum rate	0.00%
No. of agreements	3
Amount (in Dollars)	150,000
Weighted average rate	3.50%
Final maturity	2,015
Fixed to Floating Fifty Million at Three Point Five Three Percent Maturing in 2015 [Member]
Maximum rate	3.53%
Minimum rate	0.00%
No. of agreements	1
Amount (in Dollars)	50,000
Weighted average rate	3.53%
Final maturity	2,015
Fixed to Floating At 3.25% [Member]
Maximum rate	3.25%
Minimum rate	0.00%
No. of agreements	1
Amount (in Dollars)	50,000
Weighted average rate	3.25%
Final maturity	2,015
Floating to Fixed One Hundred Million [Member]
No. of agreements	1
Amount (in Dollars)	100,000
Weighted average rate	4.78%
Final maturity	2,014
Floating to Fixed Rate Two Hundred Million at 5% [Member]
No. of agreements	4
Amount (in Dollars)	$ 200,000
Weighted average rate	5.00%
Final maturity	2,017