Note 4 - Investment Securities (Details Textual) - USD ($)	Dec. 31, 2016	Dec. 31, 2015
Available-for-sale Securities Pledged as Collateral	$ 140,600,000	$ 119,100,000
Cash, FDIC Insured Amount	250,000	250,000
Securities Sold under Agreements to Repurchase	19,114,000	12,075,000
Available-for-sale Securities, Amortized Cost Basis	190,803,000	197,960,000
Call Option [Member]
Available-for-sale Securities, Amortized Cost Basis	93,800,000	68,400,000
Callable Within One Year [Member]
Available-for-sale Securities, Amortized Cost Basis	$ 27,400,000	$ 26,100,000