Note 4 - Loans and Allowance for Loan Losses (Detail) - TDR Loan Modifications (USD $) In Thousands, unless otherwise specified	Mar. 31, 2013	Dec. 31, 2012
Residential real estate
Troubled Debt Restructurings	$ 16,263	$ 16,954
Interest Only Payments [Member] | Performing to Modified Terms [Member] | Residential Real Estate Loans [Member]
Residential real estate
Troubled Debt Restructurings	249
Interest Only Payments [Member] | Performing to Modified Terms [Member] | Commercial Real Estate Nonowner Occupied [Member]
Residential real estate
Troubled Debt Restructurings	9,825	9,856
Interest Only Payments [Member] | Not Performing to Modified Terms [Member] | Residential Real Estate Loans [Member]
Residential real estate
Troubled Debt Restructurings		180
Interest Only Payments [Member] | Not Performing to Modified Terms [Member] | Commercial Real Estate Owner Occupied [Member]
Residential real estate
Troubled Debt Restructurings	675
Interest Only Payments [Member] | Not Performing to Modified Terms [Member] | Commercial Real Estate Nonowner Occupied [Member]
Residential real estate
Troubled Debt Restructurings		300
Interest Only Payments [Member] | Not Performing to Modified Terms [Member] | Commercial and Industrial [Member]
Residential real estate
Troubled Debt Restructurings		675
Interest Only Payments [Member] | Residential Real Estate Loans [Member]
Residential real estate
Troubled Debt Restructurings	249	180
Interest Only Payments [Member] | Commercial Real Estate Owner Occupied [Member]
Residential real estate
Troubled Debt Restructurings	675
Interest Only Payments [Member] | Commercial Real Estate Nonowner Occupied [Member]
Residential real estate
Troubled Debt Restructurings	9,825	10,156
Interest Only Payments [Member] | Commercial and Industrial [Member]
Residential real estate
Troubled Debt Restructurings		675
Rate Reduction [Member] | Performing to Modified Terms [Member] | Residential Real Estate Loans [Member]
Residential real estate
Troubled Debt Restructurings	426	420
Rate Reduction [Member] | Performing to Modified Terms [Member] | Commercial Real Estate Owner Occupied [Member]
Residential real estate
Troubled Debt Restructurings		440
Rate Reduction [Member] | Not Performing to Modified Terms [Member] | Commercial Real Estate Owner Occupied [Member]
Residential real estate
Troubled Debt Restructurings	440
Rate Reduction [Member] | Residential Real Estate Loans [Member]
Residential real estate
Troubled Debt Restructurings	426	420
Rate Reduction [Member] | Commercial Real Estate Owner Occupied [Member]
Residential real estate
Troubled Debt Restructurings	440	440
Maturity Extension at Lower Stated Rate Than Market Rate [Member] | Performing to Modified Terms [Member] | Commercial Real Estate Owner Occupied [Member]
Residential real estate
Troubled Debt Restructurings	183	191
Maturity Extension at Lower Stated Rate Than Market Rate [Member] | Commercial Real Estate Owner Occupied [Member]
Residential real estate
Troubled Debt Restructurings	183	191
Reduction of Principal and Interest Payments [Member] | Performing to Modified Terms [Member] | Commercial Real Estate Owner Occupied [Member]
Residential real estate
Troubled Debt Restructurings	3,800	4,222
Reduction of Principal and Interest Payments [Member] | Performing to Modified Terms [Member] | Commercial Real Estate Nonowner Occupied [Member]
Residential real estate
Troubled Debt Restructurings		670
Reduction of Principal and Interest Payments [Member] | Commercial Real Estate Owner Occupied [Member]
Residential real estate
Troubled Debt Restructurings	3,800	4,222
Reduction of Principal and Interest Payments [Member] | Commercial Real Estate Nonowner Occupied [Member]
Residential real estate
Troubled Debt Restructurings		670
Commercial Real Estate Nonowner Occupied [Member] | Performing to Modified Terms [Member] | Reduction of Principal and Interest Payments [Member]
Residential real estate
Troubled Debt Restructurings	665
Commercial Real Estate Nonowner Occupied [Member] | Reduction of Principal and Interest Payments [Member]
Residential real estate
Troubled Debt Restructurings	665
Performing to Modified Terms [Member]
Residential real estate
Troubled Debt Restructurings	15,148	15,799
Not Performing to Modified Terms [Member]
Residential real estate
Troubled Debt Restructurings	$ 1,115	$ 1,155