Note 4 - Loans and Allowance for Credit Losses (Detail) - Troubled debt restructurings (USD $) In Thousands, unless otherwise specified	Mar. 31, 2013	Dec. 31, 2012
Number of Contracts	6	5
Pre-Modification Carrying Value	$ 8,701	$ 6,709
Period-End Carrying Value	8,707	6,678
Period-End Individual Impairment Allowance	786	797
Commercial [Member]
Number of Contracts	3	3
Pre-Modification Carrying Value	1,318	1,318
Period-End Carrying Value	1,172	1,196
Period-End Individual Impairment Allowance	786	797
Commercial Real Estate Loans [Member]
Number of Contracts	3	2
Pre-Modification Carrying Value	7,383	5,391
Period-End Carrying Value	$ 7,535	$ 5,482