Note 5 - Loans Covered By FDIC Loss Share Agreements (Detail) - Carrying Value of all Purchased Covered Impaired Loans (USD $) In Thousands, unless otherwise specified	Jun. 30, 2012		Mar. 31, 2012	Dec. 31, 2011		Jun. 30, 2011	Mar. 31, 2011	Dec. 31, 2010
Consumer:
Loans covered by FDIC loss share agreements	$ 114,189	[1]	$ 129,755	$ 158,075	[1]	$ 192,899	$ 208,774	$ 231,600
Other Consumer [Member]
Consumer:
Loans covered by FDIC loss share agreements				23
Consumer Loans [Member]
Consumer:
Loans covered by FDIC loss share agreements				23
Construction Loans [Member]
Consumer:
Loans covered by FDIC loss share agreements	16,502			23,515
Single Family Residential Loans [Member]
Consumer:
Loans covered by FDIC loss share agreements	21,957			26,825
Other Commercial Real Estate Loans [Member]
Consumer:
Loans covered by FDIC loss share agreements	70,471			102,198
Real Estate Loans [Member]
Consumer:
Loans covered by FDIC loss share agreements	108,930			152,538
Other Commercial Loans [Member]
Consumer:
Loans covered by FDIC loss share agreements	5,259			5,514
Agricultural Loans [Member]
Consumer:
Loans covered by FDIC loss share agreements	0			0
Commercial Loans [Member]
Consumer:
Loans covered by FDIC loss share agreements	$ 5,259			$ 5,514

[1] These loans were not classified as non-performing assets at June 30, 2012 or December 31, 2011, as the loans are accounted for on a pooled basis and the pools are considered to be performing. Therefore, interest income, through accretion of the difference between the carrying amount of the loans and the expected cash flows, is being recognized on all purchased impaired loans. The loans are grouped in pools sharing common risk characteristics and were treated in the aggregate when applying various valuation techniques.