Note 4 - Loans and Allowance for Credit Losses (Detail) - Loans Modified in a TDR by Class (USD $) In Thousands, unless otherwise specified	Mar. 31, 2013	Dec. 31, 2012
Number of Contracsts	8	8
TDRs	$ 16,487	$ 16,496
Performing Financing Receivable [Member] | Commercial Loan [Member]
TDRs	3,954	4,449
Performing Financing Receivable [Member] | Commercial Real Estate Investment [Member]
TDRs	2,138	2,142
Performing Financing Receivable [Member] | Commercial Real Estate Owner Occupied [Member]
TDRs	4,081	4,081
Performing Financing Receivable [Member] | Construction, Commercial And Residential [Member]
TDRs	4,641	4,641
Performing Financing Receivable [Member]
TDRs	14,814	15,313
Nonperforming Financing Receivable [Member] | Commercial Loan [Member]
TDRs	495
Nonperforming Financing Receivable [Member] | Commercial Real Estate Investment [Member]
TDRs	217	217
Nonperforming Financing Receivable [Member] | Construction, Commercial And Residential [Member]
TDRs	961	966
Nonperforming Financing Receivable [Member]
TDRs	1,673	1,183
Commercial Loan [Member]
Number of Contracsts	3	3
TDRs	4,449	4,449
Commercial Real Estate Investment [Member]
Number of Contracsts	2	2
TDRs	2,355	2,359
Commercial Real Estate Owner Occupied [Member]
Number of Contracsts	1	1
TDRs	4,081	4,081
Construction, Commercial And Residential [Member]
Number of Contracsts	2	2
TDRs	$ 5,602	$ 5,607