Note 5 - Premises and Equipment, Net (Details Textual) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Operating Leases, Future Minimum Payments Due	$ 1.4
Operating Leases, Future Minimum Payments Due, Next Twelve Months	0.4
Operating Leases, Future Minimum Payments, Due in Two and Three Years	0.5
Operating Leases, Future Minimum Payments, Due in Four and Five Years	0.3
Operating Leases, Future Minimum Payments, Due Thereafter	0.2
Depreciation	$ 3.0	$ 2.9	$ 3.0