Note 4 - Loans and Allowance for Credit Losses (Detail) - Troubled debt restructurings (USD $) In Thousands, unless otherwise specified	Dec. 31, 2012	Dec. 31, 2011
Number of Contracts	5	3
Pre-Modification Carrying Value	$ 6,709	$ 3,509
Period-End Carrying Value	6,678	3,447
Period-End Individual Impairment Allowance	797	1,794
Commercial [Member]
Number of Contracts	3	2
Pre-Modification Carrying Value	1,318	326
Period-End Carrying Value	1,196	321
Period-End Individual Impairment Allowance	797
Commercial Real Estate Loans [Member]
Number of Contracts	2
Pre-Modification Carrying Value	5,391
Period-End Carrying Value	5,482
Construction [Member]
Number of Contracts		1
Pre-Modification Carrying Value		3,183
Period-End Carrying Value		3,126
Period-End Individual Impairment Allowance		$ 1,794