Note 7 - Commitments and Contingencies - (Details Textual) - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017
Operating Leases, Rent Expense, Total	$ 1.8	$ 1.3
Minimum [Member]
Non-cancelable Operating Lease Terms	1 year
Maximum [Member]
Non-cancelable Operating Lease Terms	10 years
Commitments to Extend Credit [Member]
Contractual Obligation, Total	$ 274.0
Standby Letters of Credit [Member]
Contractual Obligation, Total	$ 11.3