Note 4 - Allowance for Loan Losses (Details Textual)	3 Months Ended	9 Months Ended	12 Months Ended
	Mar. 31, 2016	Sep. 30, 2016 USD ($)	Dec. 31, 2015 USD ($)	Sep. 30, 2015 USD ($)	Dec. 31, 2014 USD ($)
Loans Not Classified as Impaired [Member] | Substandard [Member]
Loans and Leases Receivable, Gross		$ 12,450,000		$ 14,030,000
Loans and Leases Receivable, Allowance		742,000		$ 1,300,000
Substandard [Member]
Loans and Leases Receivable, Gross		31,787,000	$ 32,397,000
Allowance for Loan Losses, Loss History Period, Number of Quarters	16		8
Financing Receivable, Allowance for Credit Losses, Effect of Change in Method		(986,000)
Loan Balance For Reviewing High Risk Loans Minimum		$ 250,000
Impaired Financing Receivable, Number of Loans Below Review Threshold		160		156
Impaired Financing Receivable Recorded Investment Below Review Threshold		$ 4,600,000		$ 3,900,000
Loans and Leases Receivable, Gross		776,117,000	$ 758,636,000	764,204,000
Loans and Leases Receivable, Allowance		$ 9,203,000	$ 8,604,000	$ 8,402,000	$ 8,802,000