Note 4 - Loans and the Allowance for Loan Losses (Details Textual) xbrli-pure in Thousands	3 Months Ended		6 Months Ended		12 Months Ended
	Jun. 30, 2017 USD ($)	Jun. 30, 2016 USD ($)	Jun. 30, 2017 USD ($)	Jun. 30, 2016 USD ($)	Dec. 31, 2016 USD ($)
Financing Receivable, Modifications, Number of Contracts			0	0
Financing Receivable, Modifications, Subsequent Default, Number of Contracts			0	0
Financing Receivable, Recorded Investment, Nonaccrual Status	$ 2,910,000		$ 2,910,000		$ 2,724,000
Loans and Leases Receivable, Impaired, Interest Lost on Nonaccrual Loans	38,000	$ 31,000	89,000	$ 106,000
Financing Receivable, Recorded Investment, 90 Days Past Due and Still Accruing	0		0		0
Deferred Loan Origination Costs	541,000	$ 569,000	936,000	942,000
Impaired Financing Receivable, Recorded Investment	5,300,000		5,300,000		5,442,000
Impaired Financing Receivable, Related Allowance	480,000		480,000		366,000
Impaired Financing Receivable, with Related Allowance, Recorded Investment	1,600,000		1,600,000		1,534,000
Impaired Financing Receivable, with No Related Allowance, Recorded Investment	3,700,000		3,700,000		3,908,000
Impaired Financing Receivable, Average Recorded Investment			4,890,000	5,421,000	5,077,000
Impaired Financing Receivable, Interest Income, Accrual Method			79,000	61,000	149,000
Impaired Financing Receivable, Interest Income, Cash Basis Method			0	$ 0
Financing Receivable, Modifications, Recorded Investment	4,132,000		4,132,000		4,616,000
Financing Receivable Modifications Related Allowances	328,000		328,000		342,000
Loans and Leases Receivable, Impaired, Commitment to Lend	$ 0		$ 0		$ 0