Note 7 - Loans and Allowance for Loan Losses (Detail) - Additional Information Regarding Impaired Loans (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011
Real Estate Construction And Land Development [Member]
Cash Basis Interest Income Recognized	$ 204	$ 229	$ 573	$ 765
Real Estate Mortgage Residential [Member]
Cash Basis Interest Income Recognized	44	265	298	986
Real Estate Mortgage Farmland And Other Commercial Enterprises [Member]
Cash Basis Interest Income Recognized	608	550	1,437	1,925
Commercial And Industrial [Member]
Cash Basis Interest Income Recognized	8	39	22	146
Consumer Secured [Member]
Cash Basis Interest Income Recognized		1	5	4
Consumer Unsecured [Member]
Cash Basis Interest Income Recognized	7		12
Total [Member]
Cash Basis Interest Income Recognized	871	1,084	2,347	3,826
Real Estate Construction And Land Development [Member]
Average Of Individually Impaired Loans	26,902	44,832	37,921	55,755
Real Estate Mortgage Residential [Member]
Average Of Individually Impaired Loans	8,979	27,731	14,744	29,665
Real Estate Mortgage Farmland And Other Commercial Enterprises [Member]
Average Of Individually Impaired Loans	35,076	53,957	38,967	62,980
Commercial And Industrial [Member]
Average Of Individually Impaired Loans	214	2,989	426	3,947
Commercial Other [Member]
Average Of Individually Impaired Loans		665		224
Consumer Secured [Member]
Average Of Individually Impaired Loans	22	74	66	74
Consumer Unsecured [Member]
Average Of Individually Impaired Loans	374		251
Total [Member]
Average Of Individually Impaired Loans	71,567	130,248	92,375	152,645
Real Estate Construction And Land Development [Member]
Interest Income Recognized During Impairment	249	229	630	862
Real Estate Mortgage Residential [Member]
Interest Income Recognized During Impairment	52	270	308	1,024
Real Estate Mortgage Farmland And Other Commercial Enterprises [Member]
Interest Income Recognized During Impairment	418	560	1,419	2,038
Commercial And Industrial [Member]
Interest Income Recognized During Impairment	8	39	22	147
Commercial Other [Member]
Interest Income Recognized During Impairment		10		10
Consumer Secured [Member]
Interest Income Recognized During Impairment		1	5	4
Consumer Unsecured [Member]
Interest Income Recognized During Impairment	8		13
Total [Member]
Interest Income Recognized During Impairment	$ 735	$ 1,109	$ 2,397	$ 4,085