Note 3 - Loans and Allowance for Loan Losses (Details Textual) - USD ($)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Impaired Financing Receivable, Interest Income, Accrual Method	$ 6,000	$ 2,000	$ 4,000
Impaired Financing Receivable, Average Recorded Investment	9,331,000	12,010,000	8,110,000
Allowance for Loan and Lease Losses, Write-offs	$ 536,000	$ 1,699,000	$ 1,451,000
Weighted Average Interest Rate On Loans Receivable	4.82%	4.81%
Mortgage Receivable [Member]
Servicing Asset at Amortized Cost	$ 45,839	$ 54,722
Commercial Loans [Member]
Servicing Asset at Amortized Cost	31,425,300	5,978,363
Troubled Debt Restructurings [Member]
Allowance for Loan and Lease Losses, Period Increase (Decrease)	118,482	41,458
Allowance for Loan and Lease Losses, Write-offs	$ 0	$ 0