Note 4 - Securities - Fair Market Value of Securities Segregated by Purpose (Details) $ in Thousands	Mar. 31, 2017 USD ($)
Pledged Securities	$ 58,958
Federal Home Loan Bank Borrowings [Member]
Pledged Securities	25,342
Public Funds Collateral [Member]
Pledged Securities	33,616
Securities Pledged as Collateral [Member]
Pledged Securities	18,328
Securities Pledged as Collateral [Member] | Federal Home Loan Bank Borrowings [Member]
Pledged Securities
Securities Pledged as Collateral [Member] | Public Funds Collateral [Member]
Pledged Securities	18,328
Securities Available to Be Pledged [Member]
Pledged Securities	40,630
Securities Available to Be Pledged [Member] | Federal Home Loan Bank Borrowings [Member]
Pledged Securities	25,342
Securities Available to Be Pledged [Member] | Public Funds Collateral [Member]
Pledged Securities	$ 15,288