Note 4 - Loans Held for Investment (Details) - Non-accrual Loans - USD ($)	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Past Due TDRs:
Loans held for investment, nonaccrual basis	$ 3,197,000	$ 5,038,000
Current TDRs:
Percentage of total loans held for investment, net	0.50%	1.10%
Loans over 90 days past due, still accruing	$ 115,000	$ 389,000
Total non-performing assets	946,282,972	885,430,647
Nonperforming Financial Instruments [Member]
Current TDRs:
Loans over 90 days past due, still accruing	115,000	389,000
Other real estate owned	6,125,000	7,756,000
Total non-performing assets	$ 9,437,000	$ 13,183,000
Performing Financial Instruments [Member]
Current TDRs:
Percentage of total loans held for investment, net	0.10%	0.30%	1.10%	1.70%	4.80%
Non-TDR Loans [Member]
Past Due TDRs:
Loans held for investment, nonaccrual basis	$ 1,695,000	$ 1,798,000
Troubled Debt Restructurings [Member]
Past Due TDRs:
Loans held for investment, nonaccrual basis	1,502,000	3,240,000
Troubled Debt Restructurings [Member] | Nonperforming Financial Instruments [Member]
Past Due TDRs:
Loans held for investment, nonaccrual basis	159,000	1,233,000
Troubled Debt Restructurings [Member] | Performing Financial Instruments [Member]
Past Due TDRs:
Loans held for investment, nonaccrual basis	1,343,000	2,007,000
Residential Portfolio Segment [Member] | Real Estate Loan [Member]
Current TDRs:
Loans over 90 days past due, still accruing	115,000	389,000
Residential Portfolio Segment [Member] | Lots and Raw Land [Member]
Current TDRs:
Loans over 90 days past due, still accruing	0	0
Residential Portfolio Segment [Member] | Construction Loans [Member]
Current TDRs:
Loans over 90 days past due, still accruing	0	0
Residential Portfolio Segment [Member] | Non-TDR Loans [Member] | Real Estate Loan [Member]
Past Due TDRs:
Loans held for investment, nonaccrual basis	635,000	727,000
Residential Portfolio Segment [Member] | Non-TDR Loans [Member] | Lots and Raw Land [Member]
Past Due TDRs:
Loans held for investment, nonaccrual basis	0	11,000
Residential Portfolio Segment [Member] | Troubled Debt Restructurings [Member] | Nonperforming Financial Instruments [Member] | Real Estate Loan [Member]
Past Due TDRs:
Loans held for investment, nonaccrual basis	0	0
Residential Portfolio Segment [Member] | Troubled Debt Restructurings [Member] | Performing Financial Instruments [Member] | Real Estate Loan [Member]
Past Due TDRs:
Loans held for investment, nonaccrual basis	809,000	834,000
Commercial Portfolio Segment [Member] | Real Estate Loan [Member]
Current TDRs:
Loans over 90 days past due, still accruing	0	0
Commercial Portfolio Segment [Member] | Lots and Raw Land [Member]
Current TDRs:
Loans over 90 days past due, still accruing	0	0
Commercial Portfolio Segment [Member] | Commercial and Industrial [Member]
Current TDRs:
Loans over 90 days past due, still accruing	0	0
Commercial Portfolio Segment [Member] | Lease Receivables [Member]
Current TDRs:
Loans over 90 days past due, still accruing	0	0
Commercial Portfolio Segment [Member] | Construction Loans [Member]
Current TDRs:
Loans over 90 days past due, still accruing	0	0
Commercial Portfolio Segment [Member] | Non-TDR Loans [Member] | Real Estate Loan [Member]
Past Due TDRs:
Loans held for investment, nonaccrual basis	594,000	554,000
Commercial Portfolio Segment [Member] | Non-TDR Loans [Member] | Lots and Raw Land [Member]
Past Due TDRs:
Loans held for investment, nonaccrual basis	0	32,000
Commercial Portfolio Segment [Member] | Non-TDR Loans [Member] | Commercial Construction [Member]
Past Due TDRs:
Loans held for investment, nonaccrual basis	0	0
Commercial Portfolio Segment [Member] | Non-TDR Loans [Member] | Commercial and Industrial [Member]
Past Due TDRs:
Loans held for investment, nonaccrual basis	0	0
Commercial Portfolio Segment [Member] | Non-TDR Loans [Member] | Lease Receivables [Member]
Past Due TDRs:
Loans held for investment, nonaccrual basis	95,000	69,000
Commercial Portfolio Segment [Member] | Troubled Debt Restructurings [Member] | Nonperforming Financial Instruments [Member] | Real Estate Loan [Member]
Past Due TDRs:
Loans held for investment, nonaccrual basis	0	1,182,000
Commercial Portfolio Segment [Member] | Troubled Debt Restructurings [Member] | Nonperforming Financial Instruments [Member] | Lots and Raw Land [Member]
Past Due TDRs:
Loans held for investment, nonaccrual basis	0	0
Commercial Portfolio Segment [Member] | Troubled Debt Restructurings [Member] | Nonperforming Financial Instruments [Member] | Commercial Construction [Member]
Past Due TDRs:
Loans held for investment, nonaccrual basis	0	0
Commercial Portfolio Segment [Member] | Troubled Debt Restructurings [Member] | Nonperforming Financial Instruments [Member] | Commercial and Industrial [Member]
Past Due TDRs:
Loans held for investment, nonaccrual basis	0	0
Commercial Portfolio Segment [Member] | Troubled Debt Restructurings [Member] | Performing Financial Instruments [Member] | Real Estate Loan [Member]
Past Due TDRs:
Loans held for investment, nonaccrual basis	534,000	127,000
Commercial Portfolio Segment [Member] | Troubled Debt Restructurings [Member] | Performing Financial Instruments [Member] | Lots and Raw Land [Member]
Past Due TDRs:
Loans held for investment, nonaccrual basis	0	1,046,000
Commercial Portfolio Segment [Member] | Troubled Debt Restructurings [Member] | Performing Financial Instruments [Member] | Commercial and Industrial [Member]
Past Due TDRs:
Loans held for investment, nonaccrual basis	0	0
Commercial Portfolio Segment [Member] | Troubled Debt Restructurings [Member] | Performing Financial Instruments [Member] | Construction Loans [Member]
Past Due TDRs:
Loans held for investment, nonaccrual basis	0	0
Consumer Portfolio Segment [Member] | Real Estate Loan [Member]
Current TDRs:
Loans over 90 days past due, still accruing	0	0
Consumer Portfolio Segment [Member] | Lots and Raw Land [Member]
Current TDRs:
Loans over 90 days past due, still accruing	0	0
Consumer Portfolio Segment [Member] | Home Equity Loan [Member]
Current TDRs:
Loans over 90 days past due, still accruing	0	0
Consumer Portfolio Segment [Member] | Other Loans [Member]
Current TDRs:
Loans over 90 days past due, still accruing	0	0
Consumer Portfolio Segment [Member] | Construction Loans [Member]
Current TDRs:
Loans over 90 days past due, still accruing	0	0
Consumer Portfolio Segment [Member] | Non-TDR Loans [Member] | Real Estate Loan [Member]
Past Due TDRs:
Loans held for investment, nonaccrual basis	148,000	214,000
Consumer Portfolio Segment [Member] | Non-TDR Loans [Member] | Lots and Raw Land [Member]
Past Due TDRs:
Loans held for investment, nonaccrual basis	140,000	124,000
Consumer Portfolio Segment [Member] | Non-TDR Loans [Member] | Home Equity Loan [Member]
Past Due TDRs:
Loans held for investment, nonaccrual basis	81,000	61,000
Consumer Portfolio Segment [Member] | Non-TDR Loans [Member] | Other Loans [Member]
Past Due TDRs:
Loans held for investment, nonaccrual basis	2,000	6,000
Consumer Portfolio Segment [Member] | Troubled Debt Restructurings [Member] | Nonperforming Financial Instruments [Member] | Real Estate Loan [Member]
Past Due TDRs:
Loans held for investment, nonaccrual basis	159,000	51,000
Consumer Portfolio Segment [Member] | Troubled Debt Restructurings [Member] | Performing Financial Instruments [Member] | Lots and Raw Land [Member]
Past Due TDRs:
Loans held for investment, nonaccrual basis	$ 0	$ 0