Note 3 - Investment Securities Available for Sale (Detail) - The Amortized Cost And Estimated Fair Value Of Investments Available For Sale (USD $) In Thousands, unless otherwise specified	Mar. 31, 2013	Dec. 31, 2012
U. S. Government agency securities maturing:
Amortized Cost	$ 11,219	$ 11,469
Estimated Fair Value	11,678	11,978
Five years through ten years	70,788	60,581
Five years through ten years	74,702	65,335
Amortized Cost	310,917	290,712
Estimated Fair Value	318,431	299,820
Residential Mortgage Backed Securities [Member]
U. S. Government agency securities maturing:
Amortized Cost	189,601	170,649
Estimated Fair Value	191,578	173,083
Equity Investment Other [Member]
U. S. Government agency securities maturing:
Amortized Cost	407	407
Estimated Fair Value	349	342
US Government Debt Securities [Member]
U. S. Government agency securities maturing:
One year or less	3,000	5,038
One year or less	2,993	5,053
Amortized Cost	35,902	42,568
Estimated Fair Value	$ 37,131	$ 44,029