Note 3 - Securities - Debt Securities by Maturity (Details)	Dec. 31, 2016 USD ($)
Due in one year or less	1.24%
Due in one year or less	$ 35,608,000
Due in one year or less	$ 35,638,000
Due from one to five years	2.09%
Due from one to five years	$ 81,073,000
Due from one to five years	$ 80,872,000
Due from five to ten years	2.65%
Due from five to ten years	$ 84,422,000
Due from five to ten years	$ 81,587,000
Due after ten years	2.84%
Due after ten years	$ 86,151,000
Due after ten years	$ 80,621,000
	2.31%
Available-for-sale Debt Securities, Amortized Cost Basis	$ 336,562,000
	$ 328,060,000
Collateralized Mortgage Backed Securities [Member]
Mortgage-backed securities	1.77%
Mortgage-backed securities	$ 47,329,000
Mortgage-backed securities	$ 47,392,000
Other Debt Obligations [Member]
Mortgage-backed securities	2.66%
Mortgage-backed securities	$ 1,979,000
Mortgage-backed securities	$ 1,950,000